Science.gov

Sample records for ultraviolet diode array

  1. Nitride deep-ultraviolet light-emitting diodes with microlens array

    NASA Astrophysics Data System (ADS)

    Khizar, M.; Fan, Z. Y.; Kim, K. H.; Lin, J. Y.; Jiang, H. X.

    2005-04-01

    We report on the fabrication of 280-nm AlGaN-based deep-ultraviolet light-emitting diodes (UV LEDs) on sapphire substrates with an integrated microlens array. Microlenses with a diameter of 12μm were fabricated on the sapphire substrate by resist thermal reflow and plasma dry etching. LED devices were flip-chip bonded on high thermal conductive AlN ceramic submounts to improve the thermal dissipation, and the emitted UV light was extracted through the sapphire substrates. With the integrated microlens array, a 55% enhancement in the output power at 20-mA dc driving was achieved compared with the same LED without microlens. The light extraction enhancement is the result of the reduced internal reflections of the light caused by the microlens surface profile.

  2. Diode Laser Arrays

    NASA Astrophysics Data System (ADS)

    Botez, Dan; Scifres, Don R.

    2005-11-01

    Contributors; 1. Monolithic phase-locked semiconductor laser arrays D. Botez; 2. High power coherent, semiconductor laser master oscillator power amplifiers and amplifier arrays D. F. Welch and D. G. Mehuys; 3. Microoptical components applied to incoherent and coherent laser arrays J. R. Leger; 4. Modeling of diode laser arrays G. R. Hadley; 5. Dynamics of coherent semiconductor laser arrays H. G. Winfuland and R. K. Defreez; 6. High average power semiconductor laser arrays and laser array packaging with an emphasis for pumping solid state lasers R. Solarz; 7. High power diode laser arrays and their reliability D. R. Scifres and H. H. Kung; 8. Strained layer quantum well heterostructure laser arrays J. J. Coleman; 9. Vertical cavity surface emitting laser arrays C. J. Chang-Hasnain; 10. Individually addressed arrays of diode lasers D. Carlin.

  3. Statistical Optimization of Evaporative Light Scattering Detection for Molten Sucrose Octaacetate and Comparison With Ultraviolet Diode Array Detection Validation Parameters Using Tandem HPLC Ultraviolet Diode Array Detection/Evaporative Light Scattering Detection-Specific Stability-Indicating Method.

    PubMed

    Parmar, Rudrangi; Ghanta, Ajay; Haware, Rahul V; Johnson, Paul R; Stagner, William C

    2016-12-01

    A sucrose octaacetate (SOA) gradient HPLC evaporative light scattering detection (ELSD) and low-wavelength UV-diode array detection (UV-DAD)-specific stability-indicating method development and validation comparison is reported. A central composite response surface design and multicriteria optimization was used to maximize molten SOA area-under-the-curve response and signal-to-noise ratio. The ELSD data were also analyzed using multivariate principal component analysis, analysis of variance, and standard least squares effects modeling. The method suitability and validation parameters of both methods were compared. To the authors' knowledge, this is the first report that validates an ELSD method using a molten analyte. SOA exhibited a low molar absorptivity of 439 absorption units/cm/M in water at 210 nm requiring low-wavelength UV-DAD detection. The low-wavelength UV-DAD method provided substantially better intraday and interday precision, intraday and interday goodness-of-fit, detection limit, and quantitation limit than ELSD. ELSD exhibited a 60-fold greater area-under-the-curve response, better resolution, and 58% more theoretical plates. On balance, the UV-DAD method was chosen for SOA chemical kinetic studies. This study illustrates that ELSD may not always be the best alternative to gradient HPLC low-wavelength UV detection.

  4. Simultaneous determination three phytosterol compounds, campesterol, stigmasterol and daucosterol in Artemisia apiacea by high performance liquid chromatography-diode array ultraviolet/visible detector

    PubMed Central

    Lee, Jiwoo; Weon, Jin Bae; Yun, Bo-Ra; Eom, Min Rye; Ma, Choong Je

    2015-01-01

    Background: Artemisia apiacea is a traditional herbal medicine using treatment of eczema and jaundice in Eastern Asia, including China, Korea, and Japan. Objective: An accurate and sensitive analysis method using high performance liquid chromatography-diode array ultraviolet/visible detector and liquid chromatography–mass spectrometry for the simultaneous determination of three phytosterol compounds, campesterol, stigmasterol and daucosterol in A. apiacea was established. Materials and Methods: The analytes were separated on a Shiseido C18 column (5 μm, 4.6 mm I.D. ×250 mm) with gradient elution of 0.1% trifluoroacetic acid and acetonitrile. The flow rate was 1 mL/min and detection wavelengths were set at 205 and 254 nm. Results: Validation of the method was performed to demonstrate its linearity, precision and accuracy. The calibration curves showed good linearity (R2 > 0.9994). The limits of detection and limits of quantification were within the ranges 0.55–7.07 μg/mL and 1.67–21.44 μg/mL, respectively. And, the relative standard deviations of intra- and inter-day precision were <2.93%. The recoveries were found to be in the range of 90.03–104.91%. Conclusion: The developed method has been successfully applied to the analysis for quality control of campesterol, stigmasterol and daucosterol in A. apiacea. PMID:25829768

  5. Analysis of EU priority polycyclic aromatic hydrocarbons in food supplements using high performance liquid chromatography coupled to an ultraviolet, diode array or fluorescence detector.

    PubMed

    Danyi, Sophie; Brose, François; Brasseur, Catherine; Schneider, Yves-Jacques; Larondelle, Yvan; Pussemier, Luc; Robbens, Johan; De Saeger, Sarah; Maghuin-Rogister, Guy; Scippo, Marie-Louise

    2009-02-09

    High performance liquid chromatography coupled to an ultraviolet, diode array or fluorescence detector (HPLC/UV-FLD) has been used to set up a method to detect the 15(+1) EU priority polycyclic aromatic hydrocarbons (PAHs) in food supplements covering the categories of dried plants and plant extracts excluding oily products. A mini validation was performed and the following parameters have been determined: limit of detection, limit of quantification, precision, recovery and linearity. They were in close agreement with quality criteria described in the Commission Regulation (EC) No 333/2007 concerning the PAH benzo[a]pyrene in foodstuffs, except the not fluorescent cyclopenta[c,d]pyrene for which the UV detection leads to a higher limit of detection. Analysis of twenty commercial food supplements covering mainly the class of dried plants was performed to evaluate their PAHs contamination levels and to test the applicability of the method to various plant matrices. Fifty percent of analyzed samples showed concentration exceeding 2 microgkg(-1) for one or more PAHs.

  6. Application of high-performance liquid chromatography with ultraviolet diode array detection and refractive index detection to the determination of class composition and to the analysis of gasoline.

    PubMed

    Kamiński, Marian; Kartanowicz, Rafał; Przyjazny, Andrzej

    2004-03-12

    A method of effective application of normal-phase high-performance liquid chromatography (NP-HPLC) with ultraviolet diode array detection (DAD) and refractive index detection (RID) for the determination of class composition of gasoline and its components, i.e. for the determination of content of alkenes, aromatic and saturated hydrocarbons in gasoline meeting modern quality standards, has been developed. An aminopropyl-bonded silica stationary phase was used along with n-hexane or n-heptane as the mobile phase. A DAD signal integrated over the 207-240 nm range was used to determine alkenes. This eliminates the necessity of separating alkenes from saturates, because the latter do not absorb UV radiation above 200 nm. The content of aromatic hydrocarbons is determined by means of a refractive index detector. Calibration was based on hydrocarbon type composition determined by the fluorescent indicator adsorption method, ASTM D1319. The results obtained by the developed method were found to be consistent with those obtained by fluorescent indicator adsorption or by a multidimensional GC method (PIONA) (ASTM D5443). The method can be applied to gasoline meeting recent quality standards, irrespective of refining technology used in the production of gasoline components, including gasoline with various contents of oxygenates. The developed method cannot be used to determine the hydrocarbon type composition of gasoline that contains as a component the so-called pyrocondensate, i.e. the fraction with a boiling point up to 220 degrees C, obtained through thermal pyrolysis of distillation residues of crude oil or coal and, consequently, does not meet the quality standards. The paper includes the procedure for identification of this type of gasoline.

  7. Near-ultraviolet laser diodes for brilliant ultraviolet fluorophore excitation.

    PubMed

    Telford, William G

    2015-12-01

    Although multiple lasers are now standard equipment on most modern flow cytometers, ultraviolet (UV) lasers (325-365 nm) remain an uncommon excitation source for cytometry. Nd:YVO4 frequency-tripled diode pumped solid-state lasers emitting at 355 nm are now the primary means of providing UV excitation on multilaser flow cytometers. Although a number of UV excited fluorochromes are available for flow cytometry, the cost of solid-state UV lasers remains prohibitively high, limiting their use to all but the most sophisticated multilaser instruments. The recent introduction of the brilliant ultraviolet (BUV) series of fluorochromes for cell surface marker detection and their importance in increasing the number of simultaneous parameters for high-dimensional analysis has increased the urgency of including UV sources in cytometer designs; however, these lasers remain expensive. Near-UV laser diodes (NUVLDs), a direct diode laser source emitting in the 370-380 nm range, have been previously validated for flow cytometric analysis of most UV-excited probes, including quantum nanocrystals, the Hoechst dyes, and 4',6-diamidino-2-phenylindole. However, they remain a little-used laser source for cytometry, despite their significantly lower cost. In this study, the ability of NUVLDs to excite the BUV dyes was assessed, along with their compatibility with simultaneous brilliant violet (BV) labeling. A NUVLD emitting at 375 nm was found to excite most of the available BUV dyes at least as well as a UV 355 nm source. This slightly longer wavelength did produce some unwanted excitation of BV dyes, but at sufficiently low levels to require minimal additional compensation. NUVLDs are compact, relatively inexpensive lasers that have higher power levels than the newest generation of small 355 nm lasers. They can, therefore, make a useful, cost-effective substitute for traditional UV lasers in multicolor analysis involving the BUV and BV dyes.

  8. A Portable Diode Array Spectrophotometer.

    PubMed

    Stephenson, David

    2016-05-01

    A cheap portable visible light spectrometer is presented. The spectrometer uses readily sourced items and could be constructed by anyone with a knowledge of electronics. The spectrometer covers the wavelength range 450-725 nm with a resolution better than 5 nm. The spectrometer uses a diffraction grating to separate wavelengths, which are detected using a 128-element diode array, the output of which is analyzed using a microprocessor. The spectrum is displayed on a small liquid crystal display screen and can be saved to a micro SD card for later analysis. Battery life (2 × AAA) is estimated to be 200 hours. The overall dimensions of the unit are 120 × 65 × 60 mm, and it weighs about 200 g.

  9. Frequency-narrowed diode array bar.

    PubMed

    Babcock, Earl; Chann, Bien; Nelson, Ian A; Walker, Thad G

    2005-05-20

    We describe a method to frequency narrow multielement high-power diode bars. Using a commercial 60-W, 49-element, 1-cm-long diode array bar at 795 nm running at 45 W, we narrow the linewidth from 1000 to 64 GHz with only a loss of 33% in output power. The resulting laser light is well suited for spin-exchange optical pumping of noble gas nuclei.

  10. Recent advances in antiguided diode laser arrays

    NASA Astrophysics Data System (ADS)

    Mawst, L. J.; Botez, D.; Jansen, M.; Roth, T. J.; Zmudzinski, C.; Tu, C.; Yun, J.

    1992-06-01

    The paper discusses features of advanced antiguided diode laser arrays optimized for single-spatial-mode operation to high output power. Twenty-element antiguided arrays have been fabricated to operate reproducibly to CW power levels of 0.5 W with 48-50 percent efficiency. These devices were also shown to exhibit thousands of hours of reliable operation. The paper gives special attention to modeling and optimization of multiclad antiguided arrays and presents experimental results on multiclad antiguided arrays fabricated by either of the two techniques, the conventional self-aligned stripe and the complementary self-aligned stripe.

  11. Power semiconductor laser diode arrays characterization

    NASA Astrophysics Data System (ADS)

    Zeni, Luigi; Campopiano, Stefania; Cutolo, Antonello; D'Angelo, Giuseppe

    2003-09-01

    Nowadays, power semiconductor laser diode arrays are becoming a widespread source for a large variety of industrial applications. In particular, the availability of low-cost high-power laser diode arrays makes their use possible in the industrial context for material cutting, welding, diagnostics and processing. In the above applications, the exact control of the beam quality plays a very important role because it directly affects the reliability of the final result. In this paper, we present two different approaches useful for the characterization of the beam quality in laser diode arrays. The first one, starting from total intensity measurements on planes orthogonal to the beam propagation path, is able to deduce the working conditions of each laser setting up the array. The second one is aimed at the measurement of a global quality factor of the array itself; to this end, the empirical extension of the M2 concept to composite beams is presented along with some experimental results. As the first technique is especially intended for the non-destructive detection of design problems in the array itself and in the bias circuitry, the second one represents a powerful tool for the rapid on-line diagnostics of the laser beam during its use.

  12. The Fuge Tube Diode Array Spectrophotometer

    ERIC Educational Resources Information Center

    Arneson, B. T.; Long, S. R.; Stewart, K. K.; Lagowski, J. J.

    2008-01-01

    We present the details for adapting a diode array UV-vis spectrophotometer to incorporate the use of polypropylene microcentrifuge tubes--fuge tubes--as cuvettes. Optical data are presented validating that the polyethylene fuge tubes are equivalent to the standard square cross section polystyrene or glass cuvettes generally used in…

  13. International ultraviolet explorer solar array power degradation

    NASA Technical Reports Server (NTRS)

    Day, J. H., Jr.

    1983-01-01

    The characteristic electrical performance of each International Ultraviolet Explorer (IUE) solar array panel is evaluated as a function of several prevailing variables (namely, solar illumination, array temperature and solar cell radiation damage). Based on degradation in the current-voltage characteristics of the array due to solar cell damage accumulated over time by space charged particle radiations, the available IUE solar array power is determined for life goals up to 10 years. Best and worst case calculations are normalized to actual IUE flight data (available solar array power versus observatory position) to accurately predict the future IUE solar array output. It is shown that the IUE solar array can continue to produce more power than is required at most observatory positions for at least 5 more years.

  14. Wavelength Beam-Combined Laser Diode Arrays

    DTIC Science & Technology

    2012-01-01

    focal length f f f Diffraction grating Output...lead Water in/out Figure 3. Lincoln Laboratory-designed WBC “laser in a box.” To reduce the overall size of the WBC device, multiple folding mirrors were implemented between the diode array and the concave mirror . ...spatially merges multiple wave- length sources into a single high-inten- sity beam with an order-of-magnitude improvement in brightness compared

  15. Low-cost laser diode array

    DOEpatents

    Freitas, B.L.; Skidmore, J.A.

    1999-06-01

    A substrate is used to fabricate a low-cost laser diode array. A substrate is machined from an electrically insulative material that is thermally conductive, or two substrates can be bonded together in which the top substrate is electrically as well as thermally conductive. The substrate thickness is slightly longer than the cavity length, and the width of the groove is wide enough to contain a bar and spring (which secures the laser bar firmly along one face of the groove). The spring also provides electrical continuity from the backside of the bar to the adjacent metalization layer on the laser bar substrate. Arrays containing one or more bars can be formed by creating many grooves at various spacings. Along the groove, many bars can be adjoined at the edges to provide parallel electrical conduction. This architecture allows precise and predictable registration of an array of laser bars to a self-aligned microlens array at low cost. 19 figs.

  16. Low-cost laser diode array

    DOEpatents

    Freitas, Barry L.; Skidmore, Jay A.

    1999-01-01

    A substrate is used to fabricate a low-cost laser diode array. A substrate is machined from an electrically insulative material that is thermally conductive, or two substrates can be bonded together in which the top substrate is electrically as well as thermally conductive. The substrate thickness is slightly longer than the cavity length, and the width of the groove is wide enough to contain a bar and spring (which secures the laser bar firmly along one face of the groove). The spring also provides electrical continuity from the backside of the bar to the adjacent metalization layer on the laser bar substrate. Arrays containing one or more bars can be formed by creating many grooves at various spacings. Along the groove, many bars can be adjoined at the edges to provide parallel electrical conduction. This architecture allows precise and predictable registration of an array of laser bars to a self-aligned microlens array at low cost.

  17. Deep ultraviolet light-emitting and laser diodes

    NASA Astrophysics Data System (ADS)

    Khan, Asif; Asif, Fatima; Muhtadi, Sakib

    2016-02-01

    Nearly all the air-water purification/polymer curing systems and bio-medical instruments require 250-300 nm wavelength ultraviolet light for which mercury lamps are primarily used. As a potential replacement for these hazardous mercury lamps, several global research teams are developing AlGaN based Deep Ultraviolet (DUV) light emitting diodes (LEDs) and DUV LED Lamps and Laser Diodes over Sapphire and AlN substrates. In this paper, we review the current research focus and the latest device results. In addition to the current results we also discuss a new quasipseudomorphic device design approach. This approach which is much easier to integrate in a commercial production setting was successfully used to demonstrate UVC devices on Sapphire substrates with performance levels equal to or better than the conventional relaxed device designs.

  18. High extraction efficiency ultraviolet light-emitting diode

    DOEpatents

    Wierer, Jonathan; Montano, Ines; Allerman, Andrew A.

    2015-11-24

    Ultraviolet light-emitting diodes with tailored AlGaN quantum wells can achieve high extraction efficiency. For efficient bottom light extraction, parallel polarized light is preferred, because it propagates predominately perpendicular to the QW plane and into the typical and more efficient light escape cones. This is favored over perpendicular polarized light that propagates along the QW plane which requires multiple, lossy bounces before extraction. The thickness and carrier density of AlGaN QW layers have a strong influence on the valence subband structure, and the resulting optical polarization and light extraction of ultraviolet light-emitting diodes. At Al>0.3, thinner QW layers (<2.5 nm are preferred) result in light preferentially polarized parallel to the QW plane. Also, active regions consisting of six or more QWs, to reduce carrier density, and with thin barriers, to efficiently inject carriers in all the QWs, are preferred.

  19. Laser diode array pumped continuous wave Rubidium vapor laser.

    PubMed

    Zhdanov, B V; Stooke, A; Boyadjian, G; Voci, A; Knize, R J

    2008-01-21

    We have demonstrated continuous wave operation of a laser diode array pumped Rb laser with an output power of 8 Watts. A slope efficiency of 60% and a total optical efficiency of 45% were obtained with a pump power of 18 Watts. This laser can be scaled to higher powers by using multiple laser diode arrays or stacks of arrays.

  20. Microlens frames for laser diode arrays

    DOEpatents

    Skidmore, Jay A.; Freitas, Barry L.

    1999-01-01

    Monolithic microlens frames enable the fabrication of monolithic laser diode arrays and are manufactured inexpensively with high registration, and with inherent focal length compensation for any lens diameter variation. A monolithic substrate is used to fabricate a low-cost microlens array. The substrate is wet-etched or sawed with a series of v-grooves. The v-grooves can be created by wet-etching, by exploiting the large etch-rate selectivity of different crystal planes. The v-grooves provide a support frame for either cylindrical or custom-shaped microlenses. Because the microlens frames are formed by photolithographic semiconductor batch-processing techniques, they can be formed inexpensively over large areas with precise lateral and vertical registration. The v-groove has an important advantage for preserving the correct focus for lenses of varying diameter.

  1. Microlens frames for laser diode arrays

    DOEpatents

    Skidmore, J.A.; Freitas, B.L.

    1999-07-13

    Monolithic microlens frames enable the fabrication of monolithic laser diode arrays and are manufactured inexpensively with high registration, and with inherent focal length compensation for any lens diameter variation. A monolithic substrate is used to fabricate a low-cost microlens array. The substrate is wet-etched or sawed with a series of v-grooves. The v-grooves can be created by wet-etching, by exploiting the large etch-rate selectivity of different crystal planes. The v-grooves provide a support frame for either cylindrical or custom-shaped microlenses. Because the microlens frames are formed by photolithographic semiconductor batch-processing techniques, they can be formed inexpensively over large areas with precise lateral and vertical registration. The v-groove has an important advantage for preserving the correct focus for lenses of varying diameter. 12 figs.

  2. Ultraviolet nanoimprinted polymer nanostructure for organic light emitting diode application

    NASA Astrophysics Data System (ADS)

    Jeon, Sohee; Kang, Jae-Wook; Park, Hyung-Dol; Kim, Jang-Joo; Youn, Jae R.; Shim, Jongyoup; Jeong, Jun-ho; Choi, Dae-Geun; Kim, Ki-Don; Altun, Ali Ozhan; Kim, Se-Heon; Lee, Yong-Hee

    2008-06-01

    Light extraction efficiency of a conventional organic light emitting diode (OLED) remains limited to approximately 20% as most of the emission is trapped in the waveguide and glass modes. An etchless simple method was developed to fabricate two-dimensional nanostructures on glass substrate directly by using ultraviolet (UV) curable polymer resin and UV nanoimprint lithography in order to improve output coupling efficiency of OLEDs. The enhancement of the light extraction was predicted by the three-dimensional finite difference time domain method. OLEDs integrated on nanoimprinted substrates enhanced electroluminance intensity by up to 50% compared to the conventional device.

  3. Space Qualification of Laser Diode Arrays

    NASA Technical Reports Server (NTRS)

    Troupaki, Elisavet; Kashem, Nasir B.; Allan, Graham R.; Vasilyev, Aleksey; Stephen, Mark

    2005-01-01

    Laser instruments have great potential in enabling a new generation of remote-sensing scientific instruments. NASA s desire to employ laser instruments aboard satellites, imposes stringent reliability requirements under severe conditions. As a result of these requirements, NASA has a research program to understand, quantify and reduce the risk of failure to these instruments when deployed on satellites. Most of NASA s proposed laser missions have base-lined diode-pumped Nd:YAG lasers that generally use quasi-constant wave (QCW), 808 nm Laser Diode Arrays (LDAs). Our group has an on-going test program to measure the performance of these LDAs when operated in conditions replicating launch and orbit. In this paper, we report on the results of tests designed to measure the effect of vibration loads simulating launch into space and the radiation environment encountered on orbit. Our primary objective is to quantify the performance of the LDAs in conditions replicating those of a satellite instrument, determine their limitations and strengths which will enable better and more robust designs. To this end we have developed a systematic testing strategy to quantify the effect of environmental stresses on the optical and electrical properties of the LDA.

  4. Stacked, Filtered Multi-Channel X-Ray Diode Array

    SciTech Connect

    MacNeil, Lawrence P.; Dutra, Eric C.; Raphaelian, Mark; Compton, Steven; Jacoby, Barry

    2015-08-01

    This system meets the need for a low-cost, robust X-ray diode array to use for experiments in hostile environments on multiple platforms, and for experiments utilizing forces that may destroy the diode(s). Since these uses require a small size with a minimal single line-of-sight, a parallel array often cannot be used. So a stacked, filtered multi-channel X-ray diode array was developed that was called the MiniXRD. The design was modeled, built, and tested at National Security Technologies, LLC (NSTec) Livermore Operations (LO) to determine fundamental characteristics. Then, several different systems were fielded as ancillary “ridealong” diagnostics at several national facilities to allow us to iteratively improve the design and usability. Presented here are design considerations and experimental results. This filtered diode array is currently at Technical Readiness Level (TRL) 6.

  5. Confirmation of malachite green, gentian violet and their leuco analogs in catfish and trout tissue by high-performance liquid chromatography utilizing electrochemistry with ultraviolet-visible diode array detection and fluorescence detection.

    PubMed

    Rushing, L G; Hansen, E B

    1997-10-24

    A sensitive analytical procedure for the confirmation of residues of malachite green (MG), gentian violet (GV) and their leuco analogs (LMG and LGV) in catfish and trout tissue at 10 ng/g is described. Frozen (-20 degrees C) fish fillets were cut into small pieces and homogenized in Waring blendors. The compounds of interest were extracted from 20-g amounts of homogenized fish tissue with acetonitrile-buffer, partitioned against methylene chloride, and isolated with tandem neutral alumina and propylsulfonic acid cation-exchange solid-phase extraction cartridges. Samples of 100 microl (0.8 g equiv.) were chromatographed isocratically in 10 min using an acetonitrile-buffer mobile phase on a short-chain deactivated (SCD) reversed-phase column (150x4.6 mm I.D.) in-line with a post-column oxidation coulometric electrochemical cell (EC), a UV-Vis diode array detector and a fluorescence detector.

  6. Tunnel junction enhanced nanowire ultraviolet light emitting diodes

    SciTech Connect

    Sarwar, A. T. M. Golam; May, Brelon J.; Deitz, Julia I.; Grassman, Tyler J.; McComb, David W.; Myers, Roberto C.

    2015-09-07

    Polarization engineered interband tunnel junctions (TJs) are integrated in nanowire ultraviolet (UV) light emitting diodes (LEDs). A ∼6 V reduction in turn-on voltage is achieved by the integration of tunnel junction at the base of polarization doped nanowire UV LEDs. Moreover, efficient hole injection into the nanowire LEDs leads to suppressed efficiency droop in TJ integrated nanowire LEDs. The combination of both reduced bias voltage and increased hole injection increases the wall plug efficiency in these devices. More than 100 μW of UV emission at ∼310 nm is measured with external quantum efficiency in the range of 4–6 m%. The realization of tunnel junction within the nanowire LEDs opens a pathway towards the monolithic integration of cascaded multi-junction nanowire LEDs on silicon.

  7. Modular package for cooling a laser diode array

    DOEpatents

    Mundinger, David C.; Benett, William J.; Beach, Raymond J.

    1992-01-01

    A laser diode array is disclosed that includes a plurality of planar packages and active cooling. The laser diode array may be operated in a long duty cycle, or in continuous operation. A laser diode bar and a microchannel heat sink are thermally coupled in a compact, thin planar package having the laser diode bar located proximate to one edge. In an array, a number of such thin planar packages are secured together in a stacked configuration, in close proximity so that the laser diodes are spaced closely. The cooling means includes a microchannel heat sink that is attached proximate to the laser bar so that it absorbs heat generated by laser operation. To provide the coolant to the microchannels, each thin planar package comprises a thin inlet manifold and a thin outlet manifold connected to an inlet corridor and an outlet corridor. The inlet corridor comprises a hole extending through each of the packages in the array, and the outlet corridor comprises a hole extending through each of the packages in the array. The inlet and outlet corridors are connected to a conventional coolant circulation system. The laser diode array with active cooling has application as an optical pump for high power solid state lasers. Further, it can be incorporated in equipment such as communications devices and active sensors, and in military and space applications, and it can be useful in applications having space constraints and energy limitations.

  8. Means for phase locking the outputs of a surface emitting laser diode array

    NASA Technical Reports Server (NTRS)

    Lesh, James R. (Inventor)

    1987-01-01

    An array of diode lasers, either a two-dimensional array of surface emitting lasers, or a linear array of stripe lasers, is phase locked by a diode laser through a hologram which focuses the output of the diode laser into a set of distinct, spatially separated beams, each one focused onto the back facet of a separate diode laser of the array. The outputs of the diode lasers thus form an emitted coherent beam out of the front of the array.

  9. Diode-array UV solar spectroradiometer implementing a digital micromirror device

    NASA Astrophysics Data System (ADS)

    Feldman, A.; Burnitt, T.; Porrovecchio, G.; Smid, M.; Egli, L.; Gröbner, J.; Nield, K. M.

    2014-12-01

    The solar ultraviolet spectrum captured by commercially available diode-array spectroradiometers is dominated by stray light from longer wavelengths with higher intensity. The implementation of a digital micromirror device in an array spectroradiometer has the potential to enable the precise selection of desired wavelengths as well as the ability to reduce spectral intensity of some wavelengths via selective mirror modulation, both reducing long wavelength stray light. A prototype consisting of off-the-shelf components has been assembled to verify the validity of the base concept, and initial measurements have been performed to confirm the throughput and image qualities such as spectral resolution and astigmatism.

  10. Profiling of components of rhizoma et radix polygoni cuspidati by high-performance liquid chromatography with ultraviolet diode-array detector and ion trap/time-of-flight mass spectrometric detection

    PubMed Central

    Fu, Jinfeng; Wang, Min; Guo, Huimin; Tian, Yuan; Zhang, Zunjian; Song, Rui

    2015-01-01

    Introduction: Rhizoma et Radix Polygoni Cuspidati (Huzhang in Chinese, HZ) is a traditional medicinal plant in China. Many of the components of HZ have been proved to be bioactive while it is difficult to conduct a comprehensive chemical profiling of HZ as a consequence of the absence of efficient separation system and sensitive detective means. We developed a simple and effective method for comprehensive characterization of constituents in HZ. Objective: To develop a simple and effective method to characterize the components in HZ and provide useful information for subsequent metabolic studies of HZ. Materials and Methods: The components in HZ aqueous extract were characterized by using high performance liquid chromatography with UV diode-array detector (HPLC-DAD) and ion trap/time-of-flight mass spectrometric detection (HPLC-IT/TOF). Stilbenes, anthraquinones, gallates and tannins, naphthalenes and some other compounds were identified and confirmed by diagnostic fragment ions with accurate mass measurements, characteristic fragmentation pathways and relevant published literatures. Results: Among the 238 constituents detected in HZ, a total number of 74 constituents were identified unambiguously or tentatively, including 29 compounds reported for the first time in HZ. Conclusion: The identification and structure elucidation of these chemicals provided essential data for quality control and further in vivo metabolic studies of HZ. Key words: Polygonum cuspidatum, HPLC-DAD, HPLC-IT/TOF, qualitative analysis. PMID:26246723

  11. Monolithic millimeter-wave diode grid frequency multiplier arrays

    NASA Technical Reports Server (NTRS)

    Liu, Hong-Xia L.; Qin, X.-H.; Sjogren, L. B.; Wu, W.; Chung, E.; Domier, C. W.; Luhmann, N. C., Jr.

    1992-01-01

    Monolithic diode frequency multiplier arrays, including barrier-N-N(+) (BNN) doubler, multi-quantum-barrier-varactor (MQBV) tripler, Schottky-quantum-barrier-varactor (SQBV) tripler, and resonant-tunneling-diode (RTD) tripler arrays, have been successfully fabricated with yields between 85 and 99 percent. Frequency doubling and/or tripling have been observed for all the arrays. Output powers of 2.4-2.6 W (eta = 10-18 percent) at 66 GHz with the BNN doubler and 3.8-10 W (eta = 1.7-4 percent) at 99 GHz with the SQBV tripler have been achieved.

  12. Microchannel heatsinks for high average power laser diode arrays

    SciTech Connect

    Beach, R.; Benett, B.; Freitas, B.; Ciarlo, D.; Sperry, V.; Comaskey, B.; Emanuel, M.; Solarz, R.; Mundinger, D.

    1992-01-01

    Detailed performance results and fabrication techniques for an efficient and low thermal impedance laser diode array heatsink are presented. High duty factor or even CW operation of fully filled laser diode arrays is enabled at high average power. Low thermal impedance is achieved using a liquid coolant and laminar flow through microchannels. The microchannels are fabricated in silicon using a photolithographic pattern definition procedure followed by anisotropic chemical etching. A modular rack-and-stack architecture is adopted for the heatsink design allowing arbitrarily large two-dimensional arrays to be fabricated and easily maintained. The excellent thermal control of the microchannel cooled heatsinks is ideally suited to pump array requirements for high average power crystalline lasers because of the stringent temperature demands that result from coupling the diode light to several nanometers wide absorption features characteristic of leasing ions in crystals.

  13. Enhanced light extraction in III-nitride ultraviolet photonic crystal light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Shakya, J.; Kim, K. H.; Lin, J. Y.; Jiang, H. X.

    2004-07-01

    III-nitride photonic crystal (PC) ultraviolet (UV) light-emitting diodes (LEDs) were fabricated. Triangular arrays of the PCs with different diameters/periodicities were patterned using electron-beam lithography and inductively coupled plasma dry etching. The optical power output of LEDs was enhanced by a factor of 2.5 due to PC formation. It was observed that the optical enhancement factor depends strongly on the lattice constant and hole size of the PCs. The achievement of nitride PCs is expected to benefit many applications of III-nitride optoelectronics, particularly for the improvement of extraction efficiency in III-nitride deep-UV emitters (λ <340nm), which are crucial for many important applications, but presently have a very low quantum efficiency.

  14. Applications of microlens-conditioned laser diode arrays

    SciTech Connect

    Beach, R.J.; Emanuel, M.A.; Freitas, B.L.

    1995-01-01

    The ability to condition the radiance of laser diodes using shaped-fiber cylindrical-microlens technology has dramatically increased the number of applications that can be practically engaged by diode laser arrays. Lawrence Livermore National Laboratory (LLNL) has actively pursued optical efficiency and engineering improvements in this technology in an effort to supply large radiance-conditioned laser diode array sources for its own internal programs. This effort has centered on the development of a modular integrated laser diode packaging technology with the goal of enabling the simple and flexible construction of high average power, high density, two-dimensional arrays with integrated cylindrical microlenses. Within LLNL, the principal applications of microlens-conditioned laser diode arrays are as high intensity pump sources for diode pumped solid state lasers (DPSSLs). A simple end-pumping architecture has been developed and demonstrated that allows the radiation from microlens-conditioned, two-dimensional diode array apertures to be efficiently delivered to the end of rod lasers. To date, pump powers as high as 2.5 kW have been delivered to 3 mm diameter laser rods. Such high power levels are critical for pumping solid state lasers in which the terminal laser level is a Stark level lying in the ground state manifold. Previously, such systems have often required operation of the solid state gain medium at low temperature to freeze out the terminal laser Stark level population. The authors recently developed high intensity pump sources overcome this difficulty by effectively pumping to much higher inversion levels, allowing efficient operation at or near room temperature. Because the end-pumping technology is scalable in absolute power, the number of rare-earth ions and transitions that can be effectively accessed for use in practical DPSSL systems has grown tremendously.

  15. Microchannel cooled heatsinks for high average power laser diode arrays

    SciTech Connect

    Bennett, W.J.; Freitas, B.L.; Ciarlo, D.; Beach, R.; Sutton, S.; Emanuel, M.; Solarz, R.

    1993-01-15

    Detailed performance results for an efficient and low impedance laser diode array heatsink are presented. High duty factor and even cw operation of fully filled laser diode arrays at high stacking densities are enabled at high average power. Low thermal impedance is achieved using a liquid coolant and laminar flow through microchannels. The microchannels are fabricated in silicon using an anisotropic chemical etching process. A modular rack-and-stack architecture is adopted for heatsink design, allowing arbitrarily large two-dimensional arrays to be fabricated and easily maintained. The excellent thermal control of the microchannel heatsinks is ideally suited to pump army requirements for high average power crystalline laser because of the stringent temperature demands are required to efficiently couple diode light to several-nanometer-wide absorption features characteristic of lasing ions in crystals.

  16. Stacked, filtered multi-channel X-ray diode array

    NASA Astrophysics Data System (ADS)

    MacNeil, L. P.; Dutra, E. C.; Compton, S. M.; Jacoby, B. A.; Raphaelian, M. L.

    2015-08-01

    There are many types of X-ray diodes that are used for X-ray flux or spectroscopic measurements and for estimating the spectral shape of the VUV to soft X-ray spectrum. However, a need arose for a low cost, robust X-ray diode to use for experiments in hostile environments on multiple platforms, and for experiments that utilize forces that may destroy the diode(s). Since the typical proposed use required a small size with a minimal single line-of-sight, a parallel array could not be used. So, a stacked, filtered multi-channel X-ray diode array was developed, called the MiniXRD. To achieve significant cost savings while maintaining robustness and ease of field setup, repair, and replacement, we designed the system to be modular. The filters were manufactured in-house and cover the range from 450 eV to 5000 eV. To achieve the line-of-sight accuracy needed, we developed mounts and laser alignment techniques. We modeled and tested elements of the diode design at NSTec Livermore Operations (NSTec / LO) to determine temporal response and dynamic range, leading to diode shape and circuitry changes to optimize impedance and charge storage. We fielded individual and stacked systems at several national facilities as ancillary `ride-along' diagnostics to test and improve the design usability. We present the MiniXRD system performance which supports consideration as a viable low-cost alternative for multiple-channel low-energy X-ray measurements. This diode array is currently at Technical Readiness Level (TRL) 6.

  17. Stacked, filtered multi-channel X-ray diode array

    SciTech Connect

    MacNeil, Lawrence; Dutra, Eric; Raphaelian, Mark; Compton, Steve; Jacoby, Barry

    2015-08-01

    There are many types of X-ray diodes used for X-ray flux or spectroscopic measurements and for estimating the spectral shape of the VUV to soft X-ray spectrum. However, a need exists for a low-cost, robust X-ray diode to use for experiments in hostile environments on multiple platforms, and for experiments that utilize forces that may destroy the diode(s). Since the typical proposed use required a small size with a minimal single line-of-sight, a parallel array could not be used. So, a stacked, filtered multi-channel X-ray diode array was developed, called the MiniXRD. To achieve significant cost savings while maintaining robustness and ease of field setup, repair, and replacement, we designed the system to be modular. The filters were manufactured in-house and cover the range from 450 eV to 5000 eV. To achieve the line-of-sight accuracy needed, we developed mounts and laser alignment techniques. We modeled and tested elements of the diode design at NSTec Livermore Operations (NSTec / LO) to determine temporal response and dynamic range, leading to diode shape and circuitry changes to optimize impedance and charge storage. The authors fielded individual and stacked systems at several national facilities as ancillary "ride-along" diagnostics to test and improve the design usability. This paper presents the MiniXRD system performance, which supports consideration as a viable low-costalternative for multiple-channel low-energy X-ray measurements. This diode array is currently at Technical Readiness Level (TRL) 6.

  18. Development of ultraviolet nitride-based light emitting diodes

    NASA Astrophysics Data System (ADS)

    Katona, Thomas Matthew

    2003-10-01

    Deep ultraviolet light emitting diodes, with emission wavelengths shorter than 360 nm, have attracted interest due to their potential applications as replacement white light sources, in non-line of sight communication, for chemical and biological weapons detection, medical applications, water purification, and counterfeit detection. Light emitters in this wavelength range require AlGaN based active regions with increasing Al composition as the wavelength is decreased. High Al composition AlGaN based devices have been challenged by difficulty in growth, low electron and hole mobilities, and deep dopant levels resulting in low carrier concentrations. The combination of these factors has resulted in UV optoelectronic devices with quantum efficiency several orders of magnitude lower than their GaN/InGaN based visible counterparts. This work will details studies on alternative selective area growth techniques for dislocation reduction and the development of ultraviolet LEDs ranging from 292--340 nm. Lateral overgrowth of GaN on patterned Si (111) substrates was developed with the hope of developing seed material for bulk GaN growth. The effect of growth conditions on both the crystallographic wing tilt and crack density in the AlN/GaN films was studied. By controlling the lateral to vertical growth rate at the beginning of lateral overgrowth, the wing tilt can be effectively eliminated. We also demonstrate the first lateral overgrowth of AlN to create low threading dislocation density AlN template layers for optoelectronic device development. Deep UV quantum wells grown on this material were studied with cathodoluminescence to study the effect of dislocations on radiative recombination in deep UV devices. In addition to work on lateral overgrowth of GaN and AlN, 292, 340 nm LEDs were grown on AlN on sapphire and GaN on sapphire respectively. AlN strain relief interlayers were developed to prevent cracking of the 340 nm AlGaN based LEDs that were grown in tension on Ga

  19. Reliability of High Power Laser Diode Arrays Operating in Long Pulse Mode

    NASA Technical Reports Server (NTRS)

    Amzajerdian, Farzin; Meadows, Byron L.; Barnes, Bruce W.; Lockard, George E.; Singh, Upendra N.; Kavaya, Michael J.; Baker, Nathaniel R.

    2006-01-01

    Reliability and lifetime of quasi-CW laser diode arrays are greatly influenced by their thermal characteristics. This paper examines the thermal properties of laser diode arrays operating in long pulse duration regime.

  20. Method and system for homogenizing diode laser pump arrays

    DOEpatents

    Bayramian, Andy J

    2013-10-01

    An optical amplifier system includes a diode pump array including a plurality of semiconductor diode laser bars disposed in an array configuration and characterized by a periodic distance between adjacent semiconductor diode laser bars. The periodic distance is measured in a first direction perpendicular to each of the plurality of semiconductor diode laser bars. The diode pump array provides a pump output propagating along an optical path and characterized by a first intensity profile measured as a function of the first direction and having a variation greater than 10%. The optical amplifier system also includes a diffractive optic disposed along the optical path. The diffractive optic includes a photo-thermo-refractive glass member. The optical amplifier system further includes an amplifier slab having an input face and position along the optical path and separated from the diffractive optic by a predetermined distance. A second intensity profile measured at the input face of the amplifier slab as a function of the first direction has a variation less than 10%.

  1. Method and system for homogenizing diode laser pump arrays

    DOEpatents

    Bayramian, Andrew James

    2016-05-03

    An optical amplifier system includes a diode pump array including a plurality of semiconductor diode laser bars disposed in an array configuration and characterized by a periodic distance between adjacent semiconductor diode laser bars. The periodic distance is measured in a first direction perpendicular to each of the plurality of semiconductor diode laser bars. The diode pump array provides a pump output propagating along an optical path and characterized by a first intensity profile measured as a function of the first direction and having a variation greater than 10%. The optical amplifier system also includes a diffractive optic disposed along the optical path. The diffractive optic includes a photo-thermo-refractive glass member. The optical amplifier system further includes an amplifier slab having an input face and position along the optical path and separated from the diffractive optic by a predetermined distance. A second intensity profile measured at the input face of the amplifier slab as a function of the first direction has a variation less than 10%.

  2. Chirped microlens arrays for diode laser circularization and beam expansion

    NASA Astrophysics Data System (ADS)

    Schreiber, Peter; Dannberg, Peter; Hoefer, Bernd; Beckert, Erik

    2005-08-01

    Single-mode diode lasers are well-established light sources for a huge number of applications but suffer from astigmatism, beam ellipticity and large manufacturing tolerances of beam parameters. To compensate for these shortcomings, various approaches like anamorphic prism pairs and cylindrical telescopes for circularization as well as variable beam expanders based on zoomed telescopes for precise adjustment of output beam parameters have been employed in the past. The presented new approach for both beam circularization and expansion is based on the use of microlens arrays with chirped focal length: Selection of lenslets of crossed cylindrical microlens arrays as part of an anamorphic telescope enables circularization, astigmatism correction and divergence tolerance compensation of diode lasers simultaneously. Another promising application of chirped spherical lens array telescopes is stepwise variable beam expansion for circular laser beams of fiber or solid-state lasers. In this article we describe design and manufacturing of beam shaping systems with chirped microlens arrays fabricated by polymer-on-glass replication of reflow lenses. A miniaturized diode laser module with beam circularization and astigmatism correction assembled on a structured ceramics motherboard and a modulated RGB laser-source for photofinishing applications equipped with both cylindrical and spherical chirped lens arrays demonstrate the feasibility of the proposed system design approach.

  3. Nanostructured High Performance Ultraviolet and Blue Light Emitting Diodes for Solid State Lighting

    SciTech Connect

    Arto V. Nurmikko; Jung Han

    2005-09-30

    We report on research results in this project which synergize advanced material science approaches with fundamental optical physics concepts pertaining to light-matter interaction, with the goal of solving seminal problems for the development of very high performance light emitting diodes (LEDs) in the blue and near ultraviolet for Solid State Lighting applications. Accomplishments in the second 12 month contract period include (i) new means of synthesizing AlGaN and InN quantum dots by droplet heteroepitaxy, (ii) synthesis of AlGaInN nanowires as building blocks for GaN-based microcavity devices, (iii) progress towards direct epitaxial alignment of the dense arrays of nanowires, (iv) observation and measurements of stimulated emission in dense InGaN nanopost arrays, (v) design and fabrication of InGaN photonic crystal emitters, and (vi) observation and measurements of enhanced fluorescence from coupled quantum dot and plasmonic nanostructures. The body of results is presented in this report shows how a solid foundation has been laid, with several noticeable accomplishments, for innovative research, consistent with the stated milestones.

  4. Nanostructured High Performance Ultraviolet and Blue Light Emitting Diodes for Solid State Lighting

    SciTech Connect

    Arto V. Nurmikko; Jung Han

    2007-03-31

    We report on research results in this project which synergize advanced material science approaches with fundamental optical physics concepts pertaining to light-matter interaction, with the goal of solving seminal problems for the development of very high performance light emitting diodes (LEDs) in the blue and near ultraviolet for Solid State Lighting applications. Accomplishments in the duration of the contract period include (i) new means of synthesizing AlGaN and InN quantum dots by droplet heteroepitaxy, (ii) synthesis of AlGaInN nanowires as building blocks for GaN-based microcavity devices, (iii) progress towards direct epitaxial alignment of the dense arrays of nanowires, (iv) observation and measurements of stimulated emission in dense InGaN nanopost arrays, (v) design and fabrication of InGaN photonic crystal emitters, and (vi) observation and measurements of enhanced fluorescence from coupled quantum dot and plasmonic nanostructures. The body of results is presented in this report shows how a solid foundation has been laid, with several noticeable accomplishments, for innovative research, consistent with the stated milestones.

  5. Efficient photochemical generation of peroxycarboxylic nitric anhydrides with ultraviolet light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Rider, N. D.; Taha, Y. M.; Odame-Ankrah, C. A.; Huo, J. A.; Tokarek, T. W.; Cairns, E.; Moussa, S. G.; Liggio, J.; Osthoff, H. D.

    2015-07-01

    Photochemical sources of peroxycarboxylic nitric anhydrides (PANs) are utilized in many atmospheric measurement techniques for calibration or to deliver an internal standard. Conventionally, such sources rely on phosphor-coated low-pressure mercury (Hg) lamps to generate the UV light necessary to photo-dissociate a dialkyl ketone (usually acetone) in the presence of a calibrated amount of nitric oxide (NO) and oxygen (O2). In this manuscript, a photochemical PAN source in which the Hg lamp has been replaced by arrays of ultraviolet light-emitting diodes (UV-LEDs) is described. The output of the UV-LED source was analyzed by gas chromatography (PAN-GC) and thermal dissociation cavity ring-down spectroscopy (TD-CRDS). Using acetone, diethyl ketone (DIEK), diisopropyl ketone (DIPK), or di-n-propyl ketone (DNPK), respectively, the source produces peroxyacetic (PAN), peroxypropionic (PPN), peroxyisobutanoic (PiBN), or peroxy-n-butanoic nitric anhydride (PnBN) from NO in high yield (> 90 %). Box model simulations with a subset of the Master Chemical Mechanism (MCM) were carried out to rationalize product yields and to identify side products. The present work demonstrates that UV-LED arrays are a viable alternative to current Hg lamp setups.

  6. Deep ultraviolet (254 nm) focal plane array

    NASA Astrophysics Data System (ADS)

    Cicek, Erdem; Vashaei, Zahra; McClintock, Ryan; Razeghi, Manijeh

    2011-10-01

    We report the synthesis, fabrication and testing of a 320 × 256 focal plane array (FPA) of back-illuminated, solarblind, p-i-n, AlxGa1-xN-based detectors, fully realized within our research laboratory. We implemented a novel pulsed atomic layer deposition technique for the metalorganic chemical vapor deposition (MOCVD) growth of crackfree, thick, and high Al composition AlxGa1-xN layers. Following the growth, the wafer was processed into a 320 × 256 array of 25 μm × 25 μm pixels on a 30 μm pixel-pitch and surrounding mini-arrays. A diagnostic mini-array was hybridized to a silicon fan-out chip to allow the study of electrical and optical characteristics of discrete pixels of the FPA. At a reverse bias of 1 V, an average photodetector exhibited a low dark current density of 1.12×10-8 A/cm2. Solar-blind operation is observed throughout the array with peak detection occurring at wavelengths of 256 nm and lower and falling off three orders of magnitude by 285 nm. After indium bump deposition and dicing, the FPA is hybridized to a matching ISC 9809 readout integrated circuit (ROIC). By developing a novel masking technology, we significantly reduced the visible response of the ROIC and thus the need for external filtering to achieve solar- and visible-blind operation is eliminated. This allowed the FPA to achieve high external quantum efficiency (EQE): at 254 nm, average pixels showed unbiased peak responsivity of 75 mA/W, which corresponds to an EQE of ~37%. Finally, the uniformity of the FPA and imaging properties are investigated.

  7. Quasi-cw 808-nm 300-W laser diode arrays

    NASA Astrophysics Data System (ADS)

    Bezotosnyi, V. V.; Kozyrev, A. A.; Kondakova, N. S.; Kondakov, S. A.; Krokhin, O. N.; Mikaelyan, G. T.; Oleshchenko, V. A.; Popov, Yu. M.; Cheshev, E. A.

    2017-02-01

    Samples of 808-nm quasi-cw laser diode arrays (LDAs) with an output power exceeding 300 W, a pulse duration of 200 μs, and a pulse repetition rate of 100 Hz are developed and fabricated. The main output parameters of a set of five LDAs, including light – current characteristics, current – voltage characteristics, and emission spectra are measured. Preliminary life tests show that the LDA power remains stable for 108 pulses.

  8. Qualification of Laser Diode Arrays for Mercury Laser Altimeter Mission

    NASA Technical Reports Server (NTRS)

    Stephen, Mark; Vasilyev, Aleksey; Schafer, John; Allan, Graham R.

    2004-01-01

    NASA's requirements for high reliability, high performance satellite laser instruments have driven the investigation of many critical components; specifically, 808 nm laser diode array (LDA) pump devices. The MESSENGER mission is flying the Mercury Laser Altimeter (MLA) which is a diode-pumped Nd:YAG laser instrument designed to map the topography of Mercury. The environment imposed on the instrument by the orbital dynamics places special requirements on the laser diode arrays. In order to limit the radiative heating of the satellite from the surface of Mercury, the satellite is designed to have a highly elliptical orbit. The satellite will heat near perigee and cool near apogee. The laser power is cycled during these orbits so that the laser is on for only 30 minutes (perigee) in a 12 hour orbit. The laser heats 10 C while powered up and cools while powered down. In order to simulate these operational conditions, we designed a test to measure the LDA performance while being temperature and power cycled. Though the mission requirements are specific to NASA and performance requirements are derived from unique operating conditions, the results are general and widely applicable. We present results on the performance of twelve LDAs operating for several hundred million pulses. The arrays are 100 watt, quasi-CW, conductively-cooled, 808 nm devices. Prior to testing, we fully characterize each device to establish a baseline for individual array performance and status. Details of this characterization can be found in reference. Arrays are divided into four groups and subjected to the temperature and power cycling matrix are shown.

  9. Deep diode arrays for X-ray detection

    NASA Technical Reports Server (NTRS)

    Zemel, J. N.

    1984-01-01

    Temperature gradient zone melting process was used to form p-n junctions in bulk of high purity silicon wafers. These diodes were patterned to form arrays for X-ray spectrometers. The whole fabrication processes for these X-ray detectors are reviewed in detail. The p-n junctions were evaluated by (1) the dark diode I-V measurements, (2) the diode C sub I - V measurements, and (3) the MOS C-V measurements. The results showed that these junctions were linearly graded in charge distribution with low reverse bias leakage current flowing through them (few nA at -10 volts). The X-ray detection experiments showed that an FWHM of 500 eV was obtained from these diodes with a small bias of just -5 volts (for X-ray source Fe55). A theoretical model was proposed to explain the extra peaks found in the energy spectra and a very interesting point - cross talk effect was pointed out. This might be a solution to the problem of making really high resolution X-ray spectrometers.

  10. Linear laser diode arrays for improvement in optical disk recording

    NASA Technical Reports Server (NTRS)

    Alphonse, G. A.; Carlin, D. B.; Connolly, J. C.

    1990-01-01

    The development of individually addressable laser diode arrays for multitrack magneto-optic recorders for space stations is discussed. Three multi-element channeled substrate planar (CSP) arrays with output power greater than 30 mW with linear light vs current characteristics and stable single mode spectra were delivered to NASA. These devices have been used to demonstrate for the first time the simultaneous recording of eight data tracks on a 14-inch magneto-optic erasable disk. The yield of these devices is low, mainly due to non-uniformities inherent to the LPE growth that was used to fabricate them. The authors have recently developed the inverted CSP, based on the much more uniform MOCVD growth techniques, and have made low threshold quantum well arrays requiring about three times less current than the CSP to deliver 30 mW CW in a single spatial mode. The inverted CSP is very promising for use in space flight recorder applications.

  11. Photon counting photodiode array detector for far ultraviolet (FUV) astronomy

    NASA Technical Reports Server (NTRS)

    Hartig, G. F.; Moos, H. W.; Pembroke, R.; Bowers, C.

    1982-01-01

    A compact, stable, single-stage intensified photodiode array detector designed for photon-counting, far ultraviolet astronomy applications employs a saturable, 'C'-type MCP (Galileo S. MCP 25-25) to produce high gain pulses with a narrowly peaked pulse height distribution. The P-20 output phosphor exhibits a very short decay time, due to the high current density of the electron pulses. This intensifier is being coupled to a self-scanning linear photodiode array which has a fiber optic input window which allows direct, rigid mechanical coupling with minimal light loss. The array was scanned at a 250 KHz pixel rate. The detector exhibits more than adequate signal-to-noise ratio for pulse counting and event location. Previously announced in STAR as N82-19118

  12. Photoluminescence performance enhancement of ZnO/MgO heterostructured nanowires and their applications in ultraviolet laser diodes.

    PubMed

    Shi, Zhi-Feng; Zhang, Yuan-Tao; Cui, Xi-Jun; Zhuang, Shi-Wei; Wu, Bin; Chu, Xian-Wei; Dong, Xin; Zhang, Bao-Lin; Du, Guo-Tong

    2015-06-07

    Vertically aligned ZnO/MgO coaxial nanowire (NW) arrays were prepared on sapphire substrates by metal-organic chemical vapor deposition combined with a sputtering system. We present a comparative investigation of the morphological and optical properties of the produced heterostructures with different MgO layer thicknesses. Photoluminescence measurements showed that the optical performances of ZnO/MgO coaxial NWs were strongly dependent on the MgO layer thickness. The intensity of deep-level emission (DLE) decreased monotonously with the increase of MgO thickness, while the enhancement of ultraviolet (UV) emission showed a critical thickness of 15 nm, achieving a maximum intensity ratio (∼226) of IUV/IDLE at the same time. The significantly improved exciton emission efficiency of the coaxial NW structures allows us to study the surface passivation effect, photogenerated carrier confinement and transfer in terms of energy band theory. More importantly, we achieved an ultralow threshold (4.5 mA, 0.58 A cm(-2)) electrically driven UV lasing action based on the ZnO/MgO NW structures by constructing an Au/MgO/ZnO metal/insulator/semiconductor diode, and the continuous-current-driven diode shows a good temperature tolerance. The results obtained on the unique optical properties of ZnO/MgO coaxial NWs shed light on the design and development of ZnO-based UV laser diodes assembled with nanoscale building blocks.

  13. A preliminary analysis of a diode array for densitometry

    NASA Astrophysics Data System (ADS)

    Janes, K. A.

    1984-07-01

    A diode-array based image digitizer manufactured by the Eikonix Corp. was tested to see if it can be adapted to the exacting requirements of astronomical densitometry. As the device is presently configured, a dynamic range of 400:1 can be achieved routinely, with a positional accuracy of 2 microns or better. An area of 2048 X 2048 pixels can be scanned in about 5 minutes. Preliminary tests indicate that several relatively simple enhancements can improve both the photometric and the positional accuracy of the device.

  14. Infrared Vidicons Employing Metal-Silicon Schottky Diode Arrays

    DTIC Science & Technology

    1975-10-01

    platinum on the side of the wafer opposite to the diode array. (The iorward voltage drop calculated for the Pt-Si contact at 1 ixA is 70 mev...desired to calculate the potential at which the SiO surface will float in the geometry used in these retinae. It can be shown that the oxide...sin AW + cos Ax cos AW vc cos AW . A = l’\\ ’"• AW = R. (28) If one combines equations (28) and (24) to calculate the current flowing across the

  15. Camera vibration measurement using blinking light-emitting diode array.

    PubMed

    Nishi, Kazuki; Matsuda, Yuichi

    2017-01-23

    We present a new method for measuring camera vibrations such as camera shake and shutter shock. This method successfully detects the vibration trajectory and transient waveforms from the camera image itself. We employ a time-varying pattern as the camera test chart over the conventional static pattern. This pattern is implemented using a specially developed blinking light-emitting-diode array. We describe the theoretical framework and pattern analysis of the camera image for measuring camera vibrations. Our verification experiments show that our method has a detection accuracy and sensitivity of 0.1 pixels, and is robust against image distortion. Measurement results of camera vibrations in commercial cameras are also demonstrated.

  16. Thermal management, beam control, and packaging designs for high power diode laser arrays and pump cavity designs for diode laser array pumped rod shaped lasers

    NASA Astrophysics Data System (ADS)

    Chung, Te-Yuan

    Several novel techniques for controlling, managing and utilizing high power diode lasers are described. Low pressure water spray cooling for a high heat flux system is developed and proven to be an ideal cooling method for high power diode laser arrays. In order to enable better thermal and optical performance of diode laser arrays, a new and simple optical element, the beam control prism, is invented. It provides the ability to accomplish beam shaping and beam tilting at the same time. Several low thermal resistance diode packaging designs using beam control prisms are proposed, studied and produced. Two pump cavity designs using a diode laser array to uniformly pump rod shape gain media are also investigated.

  17. Ultra-violet light-emitting diode calibration system for timing large area scintillation detectors

    NASA Astrophysics Data System (ADS)

    Naumov, P. Yu; Runtso, M. F.; Naumov, P. P.; Maklyaev, E. F.; Kaplin, V. A.; Fomin, V. S.; Razzhivin, I. S.; Melikyan, Yu A.

    2017-01-01

    Timing large area plastic scintillation detectors are developing for the space gamma-ray telescopes now. For the in-flight calibration of these detectors the use of ultra-violet light-emitting diode, irradiating the 1 m long detector module at the center of its lateral side is suggested. The results of the measurements show the possibility of this calibration system implementation as for amplitude as for timing properties monitoring.

  18. Mid-ultraviolet light-emitting diode detects dipicolinic acid.

    SciTech Connect

    Bogart, Katherine Huderle Andersen; Lee, Stephen Roger; Temkin, Henryk; Crawford, Mary Hagerott; Dasgupta, Purnendu K.; Li, Qingyang; Allerman, Andrew Alan; Fischer, Arthur Joseph

    2005-06-01

    Dipicolinic acid (DPA, 2,6-pyridinedicarboxylic acid) is a substance uniquely present in bacterial spores such as that from anthrax (B. anthracis). It is known that DPA can be detected by the long-lived fluorescence of its terbium chelate; the best limit of detection (LOD) reported thus far using a large benchtop gated fluorescence instrument using a pulsed Xe lamp is 2 nM. We use a novel AlGaN light-emitting diode (LED) fabricated on a sapphire substrate that has peak emission at 291 nm. Although the overlap of the emission band of this LED with the absorption band of Tb-DPA ({lambda}{sub max} doublet: 273, 279 nm) is not ideal, we demonstrate that a compact detector based on this LED and an off-the-shelf gated photodetection module can provide an LOD of 0.4 nM, thus providing a basis for convenient early warning detectors.

  19. Extended temperature tuning of an ultraviolet diode laser for trapping and cooling single Yb+ ions.

    PubMed

    Nguyen, A-T; Wang, L-B; Schauer, M M; Torgerson, J R

    2010-05-01

    We describe an ultraviolet (uv) diode laser system for cooling trapped Yb(+) ions. Using four stages of thermoelectric cooling, 10 mW of light at 369.5 nm is obtained by cooling a 373.4-nm uv diode to approximately -20 degrees C. Frequency stabilization is provided by a diffraction grating mounted in the Littrow configuration which allows for a mode-hop free tuning range of approximately 25 GHz. In order to avoid water condensation, the diode laser and associated optics are placed inside an evacuated chamber. Saturated absorption spectroscopy utilizing an Yb hollow cathode lamp is performed. This laser system is currently being used to cool single ions in an experiment whose ultimate goal is to look for modern variation of the fine-structure constant.

  20. Injection locking of a high power ultraviolet laser diode for laser cooling of ytterbium atoms

    SciTech Connect

    Hosoya, Toshiyuki; Miranda, Martin; Inoue, Ryotaro; Kozuma, Mikio

    2015-07-15

    We developed a high-power laser system at a wavelength of 399 nm for laser cooling of ytterbium atoms with ultraviolet laser diodes. The system is composed of an external cavity laser diode providing frequency stabilized output at a power of 40 mW and another laser diode for amplifying the laser power up to 220 mW by injection locking. The systematic method for optimization of our injection locking can also be applied to high power light sources at any other wavelengths. Our system does not depend on complex nonlinear frequency-doubling and can be made compact, which will be useful for providing light sources for laser cooling experiments including transportable optical lattice clocks.

  1. V-shaped resonators for addition of broad-area laser diode arrays

    DOEpatents

    Liu, Bo; Liu, Yun; Braiman, Yehuda Y.

    2012-12-25

    A system and method for addition of broad-area semiconductor laser diode arrays are described. The system can include an array of laser diodes, a V-shaped external cavity, and grating systems to provide feedback for phase-locking of the laser diode array. A V-shaped mirror used to couple the laser diode emissions along two optical paths can be a V-shaped prism mirror, a V-shaped stepped mirror or include multiple V-shaped micro-mirrors. The V-shaped external cavity can be a ring cavity. The system can include an external injection laser to further improve coherence and phase-locking.

  2. Characterization of High-power Quasi-cw Laser Diode Arrays

    NASA Technical Reports Server (NTRS)

    Stephen, Mark A.; Vasilyev, Aleksey; Troupaki, Elisavet; Allan, Graham R.; Kashem, Nasir B.

    2005-01-01

    NASA s requirements for high reliability, high performance satellite laser instruments have driven the investigation of many critical components; specifically, 808 nm laser diode array (LDA) pump devices. Performance and comprehensive characterization data of Quasi-CW, High-power, laser diode arrays is presented.

  3. Ruggedized microchannel-cooled laser diode array with self-aligned microlens

    DOEpatents

    Freitas, Barry L.; Skidmore, Jay A.

    2003-11-11

    A microchannel-cooled, optically corrected, laser diode array is fabricated by mounting laser diode bars onto Si surfaces. This approach allows for the highest thermal impedance, in a ruggedized, low-cost assembly that includes passive microlens attachment without the need for lens frames. The microlensed laser diode array is usable in all solid-state laser systems that require efficient, directional, narrow bandwidth, high optical power density pump sources.

  4. Improving Reliability of High Power Quasi-CW Laser Diode Arrays for Pumping Solid State Lasers

    NASA Technical Reports Server (NTRS)

    Amzajerdian, Farzin; Meadows, Byron L.; Baker, Nathaniel R.; Barnes, Bruce W.; Baggott, Renee S.; Lockard, George E.; Singh, Upendra N.; Kavaya, Michael J.

    2005-01-01

    Most Lidar applications rely on moderate to high power solid state lasers to generate the required transmitted pulses. However, the reliability of solid state lasers, which can operate autonomously over long periods, is constrained by their laser diode pump arrays. Thermal cycling of the active regions is considered the primary reason for rapid degradation of the quasi-CW high power laser diode arrays, and the excessive temperature rise is the leading suspect in premature failure. The thermal issues of laser diode arrays are even more drastic for 2-micron solid state lasers which require considerably longer pump pulses compared to the more commonly used pump arrays for 1-micron lasers. This paper describes several advanced packaging techniques being employed for more efficient heat removal from the active regions of the laser diode bars. Experimental results for several high power laser diode array devices will be reported and their performance when operated at long pulsewidths of about 1msec will be described.

  5. Packaging of complete indium-free high reliable and high power diode laser array

    NASA Astrophysics Data System (ADS)

    Wang, Jingwei; Li, Xiaoning; Feng, Feifei; Liu, Yalong; Hou, Dong; Liu, Xingsheng

    2015-02-01

    High power diode lasers have been widely used in many fields. For many applications, a diode laser needs to be robust under on-off power-cycling as well as environmental thermal cycling conditions. To meet the requirements, the conduction cooled single bar CS-packaged diode laser arrays must have high durability to withstand thermal fatigue and long lifetime. In this paper, a complete indium-free bonding technology is presented for packaging high power diode laser arrays. Numerical simulations on the thermal behavior of CS-packaged diode laser array with different packaging structure were conducted and analyzed. Based on the simulation results, the device structure and packaging process of complete indium-free CS-packaged diode laser array were optimized. A series of high power hard solder CS (HCS) diode laser arrays were fabricated and characterized. Under the harsh working condition of 90s on and 30s off, good lifetime was demonstrated on 825nm 60W single bar CS-packaged diode laser with a lifetime test of more than 6100hours achieved so far with less 5% power degradation and less 1.5nm wavelength shift. Additionally, the measurement results indicated that the lower smile of complete indium-free CS-packaged diode laser arrays were achieved by advanced packaging process.

  6. Facile fabrication of a ultraviolet tunable MoS{sub 2}/p-Si junction diode

    SciTech Connect

    Serrano, William; Pinto, Nicholas J.; Naylor, Carl H.; Kybert, Nicholas J.; Johnson, A. T. Charlie

    2015-05-11

    Chemical vapor deposition grown MoS{sub 2} single crystals were transferred onto the edge of a p-Si/SiO{sub 2} wafer, forming an abrupt heterogeneous junction diode at the MoS{sub 2}/p-Si interface. When electrically characterized as a field effect transistor, MoS{sub 2} exhibits an n-type response and can be doped in the presence of ultraviolet (UV) light. As a diode, it operates satisfactorily in air, but has higher currents in vacuum with a turn on voltage of ∼1.3 V and an on/off ratio of 20 at ±2 V. UV irradiation increases the diode on state current, decreases the turn-on voltage, and reduces the ideality parameter below 2. These changes are reversible after annealing in air as desorption of electron trapping species like O{sub 2}{sup −} and H{sub 2}O{sup −} are believed responsible for this effect. A circuit integrating this diode was used to rectify a 1 kHz signal with an efficiency of 12%. Its simple design, coupled with the ability to clip AC signals, sense UV light, and reversibly tune these diodes, makes them inexpensive, multifunctional, and usable as active or passive circuit components in complex electronics.

  7. Thin planar package for cooling an array of edge-emitting laser diodes

    DOEpatents

    Mundinger, David C.; Benett, William J.

    1992-01-01

    A laser diode array is disclosed that includes a plurality of planar assemblies and active cooling of each assembly. The laser diode array may be operated in a long duty cycle, or in continuous operation. A laser diode bar and a microchannel heat sink are thermally coupled in a compact, thin planar assembly having the laser diode bar located proximate to one edge. In an array, a number of such thin planar assemblies are secured together in a stacked configuration, in close proximity so that the laser diodes are spaced closely. The cooling means includes a microchannel heat sink proximate to the laser diode bar to absorb heat generated by laser operation. To provide the coolant to the microchannels, each thin planar assembly comprises passageways that connect the microchannels to inlet and outlet corridors. Each inlet passageway may comprise a narrow slot that directs coolant into the microchannels and increases the velocity of flow therethrough. The corridors comprises holes extending through each of the assemblies in the array. The inlet and outlet corridors are connected to a conventional coolant circulation system. The laser diode array with active cooling has applications as an optical pump for high power solid state lasers, or by mating the diodes with fiber optic lenses. Further, the arrays can be useful in applications having space constraints and energy limitations, and in military and space applications. The arrays can be incorporated in equipment such as communications devices and active sensors.

  8. By-Pass Diode Temperature Tests of a Solar Array Coupon under Space Thermal Environment Conditions

    NASA Technical Reports Server (NTRS)

    Wright, Kenneth H.; Schneider, Todd A.; Vaughn, Jason A.; Hoang, Bao; Wong, Frankie; Wu, Gordon

    2016-01-01

    By-Pass diodes are a key design feature of solar arrays and system design must be robust against local heating, especially with implementation of larger solar cells. By-Pass diode testing was performed to aid thermal model development for use in future array designs that utilize larger cell sizes that result in higher string currents. Testing was performed on a 56-cell Advanced Triple Junction solar array coupon provided by SSL. Test conditions were vacuum with cold array backside using discrete by-pass diode current steps of 0.25 A ranging from 0 A to 2.0 A.

  9. a Comparison of Different Coherent Deep Ultraviolet Generations Using Second Harmonic Generation with Blue Laser Diode Excitation

    NASA Astrophysics Data System (ADS)

    Tangtrongbenchasil, C.; Nonaka, K.

    2008-11-01

    Nano-focus beam applications of short wavelength approximately 220 nm now play important roles in engineering and industrial sections. At present, light sources at approximately 220 nm are commercially available but large size, difficult to maintain, and expensive. Compact wavelength tunable and cost effective light sources at approximately 220 nm are required. Laser diode with sum-frequency generation methods are employed to generated the shorter wavelength approximately 220 nm. This paper presents comparison of second harmonic generation schemes using a nonlinear optic crystal and two types of laser diode, which are a 440 nm single mode blue laser diode and a 450 nm multimode Fabry-Perot blue laser diode, has potential to generate wide tunable coherent deep ultraviolet-c at approximately 220 nm. Using the blue laser diode with the sum-frequency technique, a high second harmonic power is hardly observed due to low conversion efficiency. The best performance of second harmonic generation using blue laser diode, nonlinear optic crystal, and an high-Q external cavity laser diode was observed as 1.1 μW second harmonic ultraviolet-c power at 224.45 nm ultraviolet-c wavelength and 5.75 nm ultraviolet wavelength tunability. In addition, the improvement of increasing second harmonic power approximately 220 nm and the limitation of wavelength tuning of short wavelength are also theoretically discussed in this paper.

  10. Linewidth-tunable laser diode array for rubidium laser pumping

    SciTech Connect

    Li Zhiyong; Tan Rongqing; Xu Cheng; Li Lin

    2013-02-28

    To optimise the pump source for a high-power diodepumped rubidium vapour laser, we have designed a laser diode array (LDA) with a narrowed and tunable linewidth and an external cavity formed by two volume Bragg gratings (VBGs). Through controlling the temperature differences between the two VBGs, the LDA linewidth, which was 1.8 nm before mounting the two VBGs, was tunable from 100 pm to 0.2 nm, while the output power changed by no more than 4 %. By changing simultaneously the temperature in both VBGs, the centre wavelength in air of the linewidth-tunable LDA was tunable from 779.40 nm to 780.05 nm. (control of laser radiation parameters)

  11. Silicon technologies for arrays of Single Photon Avalanche Diodes

    PubMed Central

    Ceccarelli, Francesco; Rech, Ivan; Ghioni, Massimo

    2016-01-01

    In order to fulfill the requirements of many applications, we recently developed a new technology aimed at combining the advantages of traditional thin and thick silicon Single Photon Avalanche Diodes (SPAD). In particular we demonstrated single-pixel detectors with a remarkable improvement in the Photon Detection Efficiency in the red/near-infrared spectrum (e.g. 40% at 800nm) while maintaining a timing jitter better than 100ps. In this paper we discuss the limitations of such Red-Enhanced (RE) technology from the point of view of the fabrication of small arrays of SPAD and we propose modifications to the structure aimed at overcoming these issues. We also report the first preliminary experimental results attained on devices fabricated adopting the improved structure. PMID:27761058

  12. Application of HPLC with diode array detection in tribology

    SciTech Connect

    Lehotay, J.; Oktavec, D. . Dept. of Analytical Chemistry)

    1994-01-01

    A strategy for the analysis of engine oils is described based on the correlation between previously developed methods and HPLC. The areas of some chromatographic peaks of oil samples were linearly correlated to: covered kilometers, the kinematic viscosity, the amount of insoluble compounds in heptane, Conradson's carbonized residue, the number of alkalinity and the carbonyl number. The detection is performed by a diode array detector, simultaneously providing structural information and quantitative data. The results are compared with other analytical methods, which are used for the evaluation of the oil quality. The main aim of this work was to investigate a number of parameters to find correlation between HPLC results and another parameters that characterized the properties of oil wear.

  13. Single Photon Avalanche Diodes: Towards the Large Bidimensional Arrays

    PubMed Central

    Privitera, Simona; Tudisco, Salvatore; Lanzanò, Luca; Musumeci, Francesco; Pluchino, Alessandro; Scordino, Agata; Campisi, Angelo; Cosentino, Luigi; Finocchiaro, Paolo; Condorelli, Giovanni; Mazzillo, Massimo; Lombardo, Salvo; Sciacca, Emilio

    2008-01-01

    Single photon detection is one of the most challenging goals of photonics. In recent years, the study of ultra-fast and/or low-intensity phenomena has received renewed attention from the academic and industrial communities. Intense research activity has been focused on bio-imaging applications, bio-luminescence, bio-scattering methods, and, more in general, on several applications requiring high speed operation and high timing resolution. In this paper we present design and characterization of bi-dimensional arrays of a next generation of single photon avalanche diodes (SPADs). Single photon sensitivity, dark noise, afterpulsing and timing resolution of the single SPAD have been examined in several experimental conditions. Moreover, the effects arising from their integration and the readout mode have also been deeply investigated. PMID:27873777

  14. An Analysis of the Far-Field Radiation Pattern of the Ultraviolet Light-Emitting Diode (LED) Engin LZ4-00UA00 Diode with and without Beam Shaping Optics

    DTIC Science & Technology

    2015-09-01

    SEP 2015 US Army Research Laboratory An Analysis of the Far-Field Radiation Pattern of the Ultraviolet Light - Emitting Diode (LED) Engin...Radiation Pattern of the Ultraviolet Light - Emitting Diode (LED) Engin LZ4-00UA00 Diode with and without Beam Shaping Optics 5a. CONTRACT NUMBER... light - emitting diode (LED), with and without beam shaping optics. This LED has 4 emitters arranged in a square pattern that are off-center from the

  15. Short range laser obstacle detector. [for surface vehicles using laser diode array

    NASA Technical Reports Server (NTRS)

    Kuriger, W. L. (Inventor)

    1973-01-01

    A short range obstacle detector for surface vehicles is described which utilizes an array of laser diodes. The diodes operate one at a time, with one diode for each adjacent azimuth sector. A vibrating mirror a short distance above the surface provides continuous scanning in elevation for all azimuth sectors. A diode laser is synchronized with the vibrating mirror to enable one diode laser to be fired, by pulses from a clock pulse source, a number of times during each elevation scan cycle. The time for a given pulse of light to be reflected from an obstacle and received is detected as a measure of range to the obstacle.

  16. Effect of interface layer on the performance of high power diode laser arrays

    NASA Astrophysics Data System (ADS)

    Zhang, Pu; Wang, Jingwei; Xiong, Lingling; Li, Xiaoning; Hou, Dong; Liu, Xingsheng

    2015-02-01

    Packaging is an important part of high power diode laser (HPLD) development and has become one of the key factors affecting the performance of high power diode lasers. In the package structure of HPLD, the interface layer of die bonding has significant effects on the thermal behavior of high power diode laser packages and most degradations and failures in high power diode laser packages are directly related to the interface layer. In this work, the effects of interface layer on the performance of high power diode laser array were studied numerically by modeling and experimentally. Firstly, numerical simulations using finite element method (FEM) were conducted to analyze the effects of voids in the interface layer on the temperature rise in active region of diode laser array. The correlation between junction temperature rise and voids was analyzed. According to the numerical simulation results, it was found that the local temperature rise of active region originated from the voids in the solder layer will lead to wavelength shift of some emitters. Secondly, the effects of solder interface layer on the spectrum properties of high power diode laser array were studied. It showed that the spectrum shape of diode laser array appeared "right shoulder" or "multi-peaks", which were related to the voids in the solder interface layer. Finally, "void-free" techniques were developed to minimize the voids in the solder interface layer and achieve high power diode lasers with better optical-electrical performances.

  17. Enhanced out-coupling efficiency of organic light-emitting diodes using an nanostructure imprinted by an alumina nanohole array

    SciTech Connect

    Endo, Kuniaki; Adachi, Chihaya

    2014-03-24

    We demonstrate organic light-emitting diodes (OLEDs) with enhanced out-coupling efficiency containing nanostructures imprinted by an alumina nanohole array template that can be applied to large-emitting-area and flexible devices using a roll-to-roll process. The nanostructures are imprinted on a glass substrate by an ultraviolet nanoimprint process using an alumina nanohole array mold and then an OLED is fabricated on the nanostructures. The enhancement of out-coupling efficiency is proportional to the root-mean-square roughness of the nanostructures, and a maximum improvement of external electroluminescence quantum efficiency of 17% is achieved. The electroluminescence spectra of the OLEDs indicate that this improvement is caused by enhancement of the out-coupling of surface plasmon polaritons.

  18. Advancement of High Power Quasi-CW Laser Diode Arrays For Space-based Laser Instruments

    NASA Technical Reports Server (NTRS)

    Amzajerdian, Farzin; Meadows, Byron L.; Baker, nathaniel R.; Baggott, Renee S.; Singh, Upendra N.; Kavaya, Michael J.

    2004-01-01

    Space-based laser and lidar instruments play an important role in NASA s plans for meeting its objectives in both Earth Science and Space Exploration areas. Almost all the lidar instrument concepts being considered by NASA scientist utilize moderate to high power diode-pumped solid state lasers as their transmitter source. Perhaps the most critical component of any solid state laser system is its pump laser diode array which essentially dictates instrument efficiency, reliability and lifetime. For this reason, premature failures and rapid degradation of high power laser diode arrays that have been experienced by laser system designers are of major concern to NASA. This work addresses these reliability and lifetime issues by attempting to eliminate the causes of failures and developing methods for screening laser diode arrays and qualifying them for operation in space.

  19. Monolayer graphene film on ZnO nanorod array for high-performance Schottky junction ultraviolet photodetectors.

    PubMed

    Nie, Biao; Hu, Ji-Gang; Luo, Lin-Bao; Xie, Chao; Zeng, Long-Hui; Lv, Peng; Li, Fang-Ze; Jie, Jian-Sheng; Feng, Mei; Wu, Chun-Yan; Yu, Yong-Qiang; Yu, Shu-Hong

    2013-09-09

    A new Schottky junction ultraviolet photodetector (UVPD) is fabricated by coating a free-standing ZnO nanorod (ZnONR) array with a layer of transparent monolayer graphene (MLG) film. The single-crystalline [0001]-oriented ZnONR array has a length of about 8-11 μm, and a diameter of 100∼600 nm. Finite element method (FEM) simulation results show that this novel nanostructure array/MLG heterojunction can trap UV photons effectively within the ZnONRs. By studying the I-V characteristics in the temperature range of 80-300 K, the barrier heights of the MLG film/ZnONR array Schottky barrier are estimated at different temperatures. Interestingly, the heterojunction diode with typical rectifying characteristics exhibits a high sensitivity to UV light illumination and a quick response of millisecond rise time/fall times with excellent reproducibility, whereas it is weakly sensitive to visible light irradiation. It is also observed that this UV photodetector (PD) is capable of monitoring a fast switching light with a frequency as high as 2250 Hz. The generality of the above results suggest that this MLG film/ZnONR array Schottky junction UVPD will have potential application in future optoelectronic devices.

  20. Time-resolved electroluminescence studies of III-nitride ultraviolet photonic-crystal light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Shakya, J.; Lin, J. Y.; Jiang, H. X.

    2004-09-01

    Transient responses of III-nitride photonic-crystal (PC) ultraviolet (UV) light-emitting diodes (LEDs) were measured by picosecond time-resolved electroluminescence (EL) spectroscopy. Triangular arrays of PCs with different diameters/periodicities were fabricated on 333nmUV LEDs for enhancing light extraction efficiency using electron-beam lithography and inductively coupled-plasma dry etching. With the incorporation of PCs on LEDs, the EL decay time constant τ decreases systematically with the increase of the etched sidewall area indicating the strong effect of the surface recombination. The surface recombination velocities on the p-type epitaxial surface and on the sidewall of etched holes on LEDs were determined to be 1.73×104cm /s and 1.48×105cm/s, respectively. The angular distribution of light emission from LEDs with PCs shows slight narrowing in far-field pattern. Because of the increased transient response along with enhanced light extraction, the incorporation of PCs in UV LEDs provide an effective method to control the modulation speed of UV LEDs, which could be very useful for many applications.

  1. Triggering GaAs lock-on switches with laser diode arrays

    SciTech Connect

    Loubriel, G.M.; Buttram, M.T.; Helgeson, W.D.; McLaughlin, D.L.; O'Malley, M.W.; Zutavern, F.J. ); Rosen, A.; Stabile, P.J. )

    1990-01-01

    Laser diode arrays have been used to trigger GaAs Photoconducting Semiconductor Switches (PCSS) charged to voltages of up to 60 kV and conducting currents of 580 A. The driving forces behind the use of laser diode arrays are compactness, elimination of complicated optics, and the ability to run at high repetition rates. Laser diode arrays are compactness, elimination of complicated optics, and the ability to run at high repetition rates. Laser diode arrays can trigger GaAs at high fields as the result of a new switching mode (lock-on) with very high carrier number gain. We have achieved switching of up to 10 MW in a 60 {Omega} system, with a pulse rise time of 500 ps. At 1.2 MW we have achieved repetition rates of 1 kHz with switch rise time of 500 ps for 10{sup 5} shots. The laser diode array used for these experiments delivers a 166 W pulse. In a single shot mode we have switched 4 kA with a flash lamp pumped laser and 600 A with the 166 W array. 7 refs., 5 figs.

  2. Improved calibration technique of the infrared imaging bolometer using ultraviolet light-emitting diodes.

    PubMed

    Drapiko, E; Peterson, B; Alekseev, A; Seo, D C

    2010-10-01

    The technique used until recently utilizing the Ne-He laser for imaging bolometer foils calibration [B. J. Peterson et al., J. Plasma Fusion Res. 2, S1018 (2007)] has showed several issues. The method was based on irradiation of 1 cm spaced set of points on a foil by the laser beam moved by set of mirrors. Issues were the nonuniformity of laser power due to the vacuum window transmission nonuniformity and high reflection coefficient for the laser. Also, due to the limited infrared (IR) window size, it was very time consuming. The new methodology uses a compact ultraviolet (uv) light-emitting diodes installed inside the vacuum chamber in a fixed position and the foil itself will be moved in the XY directions by two vacuum feedthroughs. These will help to avoid the above mentioned issues due to lack of a vacuum window, fixed emitters, higher uv power absorption, and a fixed IR camera position.

  3. Advanced Oxidation of Tartrazine and Brilliant Blue with Pulsed Ultraviolet Light Emitting Diodes.

    PubMed

    Scott, Robert; Mudimbi, Patrick; Miller, Michael E; Magnuson, Matthew; Willison, Stuart; Phillips, Rebecca; Harper, Willie F

    2017-01-01

      This study investigated the effect of ultraviolet light-emitting diodes (UVLEDs) coupled with hydrogen peroxide as an advanced oxidation process (AOP) for the degradation of two test chemicals. Brilliant Blue FCF consistently exhibited greater degradation than tartrazine, with 83% degradation after 300 minutes at the 100% duty cycle compared with only 17% degradation of tartrazine under the same conditions. These differences are attributable to the structural properties of the compounds. Duty cycle was positively correlated with the first-order rate constants (k) for both chemicals but, interestingly, negatively correlated with the normalized first-order rate constants (k/duty cycle). Synergistic effects of both hydraulic mixing and LED duty cycle were manifested as novel oscillations in the effluent contaminant concentration. Further, LED output and efficiency were dependent upon duty cycle and less efficient over time perhaps due to heating effects on semiconductor performance.

  4. Structural and interface properties of an AlN diamond ultraviolet light emitting diode

    SciTech Connect

    Miskys, C.R.; Garrido, J.A.; Hermann, M.; Eickhoff, M.; Nebel, C.E.; Stutzmann, M.; Vogg, G.

    2004-10-25

    Two practically fully relaxed AlN domains were identified by x-ray diffractometry for AlN grown on (100) diamond. The epitaxial orientation relationships (0001)[1010] AlN{sup I} parallel (100)[011] diamond for the predominant AlN domain (type I) and (0001)[1210] AlN{sup II} parallel (100)[011] diamond for the second domain (type II) are obtained. Surface morphology measurements corroborate the good structural quality of the AlN film. In addition, the intrinsic built-in voltage of a n-AlN/p-diamond diode was determined as 1.15 V. By spectrally resolved photocurrent measurements, the ultraviolet electroluminescence emission was confirmed to originate at the heterojunction interface, and is most probably due to a defect center.

  5. A 2-D diode array and analysis software for verification of intensity modulated radiation therapy delivery.

    PubMed

    Jursinic, Paul A; Nelms, Ben E

    2003-05-01

    An analysis is made of a two-dimensional array of diodes that can be used for measuring dose generated in a plane by a radiation beam. This measuring device is the MapCHECK Model 1175 (Sun Nuclear, Melbourne, FL). This device has 445 N-type diodes in a 22 x 22 cm2 2-D array with variable spacing. The entire array of diodes is easily calibrated to allow for measurements in absolute dose. For IMRT quality assurance, each beam is measured individually with the beam central axis oriented perpendicular to the plane of diodes. Software is available to do the analytical comparison of measurements versus dose distributions calculated by a treatment planning system. Comparison criteria of percent difference and distance-to-agreement are defined by the operator. Data are presented that show the diode array has linear response when beam fluence changes by over 300-fold, which is typical of the level of modulation in intensity modulated radiation therapy, IMRT, beams. A linear dependence is also shown for a 100-fold change in monitors units delivered. Methods for how this device can be used in the clinic for quality assurance of IMRT fields are described. Measurements of typical IMRT beams that are modulated by compensators and MLCs are presented with comparisons to treatment planning system dose calculations. A time analysis is done for typical IMRT quality assurance measurements. The setup, calibration, and analysis time for the 2-D diode array are on the order of 20 min, depending on numbers of fields. This is significantly less time than required to do similar analysis with radiographic film. The 2-D diode array is ideal for per-plan quality assurance after an IMRT system is fully commissioned.

  6. Application of ultraviolet light-emitting diodes (UV-LEDs) for water disinfection: A review.

    PubMed

    Song, Kai; Mohseni, Madjid; Taghipour, Fariborz

    2016-05-01

    Ultraviolet (UV) disinfection is an effective technology for the inactivation of pathogens in water and is of growing interest for industrial application. A new UV source - ultraviolet light-emitting diode (UV-LED) - has emerged in the past decade with a number of advantages compared to traditional UV mercury lamps. This promising alternative raises great interest in the research on application of UV-LEDs for water treatment. Studies on UV-LED water disinfection have increased during the past few years. This article presents a comprehensive review of recent studies on UV-LEDs with various wavelengths for the inactivation of different microorganisms. Many inconsistent and incomparable data were found from published studies, which underscores the importance of establishing a standard protocol for studying UV-LED inactivation of microorganisms. Different UV sensitivities to UV-LEDs and traditional UV lamps were observed in the literature for some microorganisms, which requires further investigation for a better understanding of microorganism response to UV-LEDs. The unique aspects of UV-LEDs improve inactivation effectiveness by applying LED special features, such as multiple wavelengths and pulsed illumination; however, more studies are needed to investigate the influencing factors and mechanisms. The special features of UV-LEDs offer the flexibility of novel reactor designs for a broad application of UV-LED reactors.

  7. Defect-Enabled Electrical Current Leakage in Ultraviolet Light-Emitting Diodes

    DOE PAGES

    Moseley, Michael William; Allerman, Andrew A.; Crawford, Mary H.; ...

    2015-04-13

    The AlGaN materials system offers a tunable, ultra-wide bandgap that is exceptionally useful for high-power electronics and deep ultraviolet optoelectronics. Moseley et al. (pp. 723–726) investigate a structural defect known as an open-core threading dislocation or ''nanopipe'' that is particularly detrimental to devices that employ these materials. Furthermore, an AlGaN thin film was synthesized using metal-organic chemical-vapor deposition. Electrical current leakage is detected at a discrete point using a conductive atomic-force microscope (CAFM). However, no physical feature or abnormality at this location was visible by an optical microscope. The AlGaN thin film was then etched in hot phosphoric acid, andmore » the same location that was previously analyzed was revisited with the CAFM. The point that previously exhibited electrical current leakage had been decorated with a 1.1 μm wide hexagonal pit, which identified the site of electrical current leakage as a nanopipe and allows these defects to be easily observed by optical microscopy. Moreover, with this nanopipe identification and quantification strategy, the authors were able to correlate decreasing ultraviolet light-emitting diode optical output power with increasing nanopipe density.« less

  8. Defect-Enabled Electrical Current Leakage in Ultraviolet Light-Emitting Diodes

    SciTech Connect

    Moseley, Michael William; Allerman, Andrew A.; Crawford, Mary H.; Wierer, Jonathan; Smith, Michael L.; Biedermann, Laura

    2015-04-13

    The AlGaN materials system offers a tunable, ultra-wide bandgap that is exceptionally useful for high-power electronics and deep ultraviolet optoelectronics. Moseley et al. (pp. 723–726) investigate a structural defect known as an open-core threading dislocation or ''nanopipe'' that is particularly detrimental to devices that employ these materials. Furthermore, an AlGaN thin film was synthesized using metal-organic chemical-vapor deposition. Electrical current leakage is detected at a discrete point using a conductive atomic-force microscope (CAFM). However, no physical feature or abnormality at this location was visible by an optical microscope. The AlGaN thin film was then etched in hot phosphoric acid, and the same location that was previously analyzed was revisited with the CAFM. The point that previously exhibited electrical current leakage had been decorated with a 1.1 μm wide hexagonal pit, which identified the site of electrical current leakage as a nanopipe and allows these defects to be easily observed by optical microscopy. Moreover, with this nanopipe identification and quantification strategy, the authors were able to correlate decreasing ultraviolet light-emitting diode optical output power with increasing nanopipe density.

  9. Performance of high-power laser diode arrays for spaceborne lasers.

    PubMed

    Durand, Yannig; Culoma, Alain; Meynart, Roland; Pinsard, Jean-Luc; Volluet, Gerard

    2006-08-01

    The adequacy of commercial quasi-continuous high-power laser diode arrays (HPLDAs) as pump sources for spaceborne lasers has been assessed by endurance tests up to 3 x 10(9) shots under various stress conditions, vacuum operation up to 0.36 x 10(9) shots, and proton radiation tests. Observations of the evolution of the electro-optic parameters and of the near-field patterns of the HPLDAs during endurance tests have revealed that some diode bars could reach the required lifetime of a multibillion shots, suggesting how to build long lifetime HPLDAs by proper selection of the diode bars. The robustness of the HPLDAs against the proton environment experienced in a typical low Earth orbit has been checked. Finally, high-power laser diode arrays have been operated under vacuum, showing a behavior similar to that of HPLDAs operating in atmospheric conditions.

  10. Wide-aperture laser diode array in the external V-shaped cavity

    SciTech Connect

    Svetikov, V V; Nurligareev, D Kh

    2014-09-30

    The operation of a wide-aperture laser diode array with the radiation wavelength 980 nm in external V-shaped symmetric and asymmetric cavities is experimentally studied. The regimes of stable oscillation are studied as functions of the feedback beam direction. The spectra and the intensity distribution of radiation in the far zone are presented for the laser diode in symmetric and asymmetric cavities. Tuning of the radiation wavelength is demonstrated using the Littman geometry in the asymmetric cavity. (lasers)

  11. High density, optically corrected, micro-channel cooled, v-groove monolithic laser diode array

    DOEpatents

    Freitas, B.L.

    1998-10-27

    An optically corrected, micro-channel cooled, high density laser diode array achieves stacking pitches to 33 bars/cm by mounting laser diodes into V-shaped grooves. This design will deliver > 4kW/cm{sup 2} of directional pulsed laser power. This optically corrected, micro-channel cooled, high density laser is usable in all solid state laser systems which require efficient, directional, narrow bandwidth, high optical power density pump sources. 13 figs.

  12. High density, optically corrected, micro-channel cooled, v-groove monolithic laser diode array

    DOEpatents

    Freitas, Barry L.

    1998-01-01

    An optically corrected, micro-channel cooled, high density laser diode array achieves stacking pitches to 33 bars/cm by mounting laser diodes into V-shaped grooves. This design will deliver>4kW/cm2 of directional pulsed laser power. This optically corrected, micro-channel cooled, high density laser is usable in all solid state laser systems which require efficient, directional, narrow bandwidth, high optical power density pump sources.

  13. Fiber optic coupling of a microlens conditioned, stacked semiconductor laser diode array

    DOEpatents

    Beach, R.J.; Benett, W.J.; Mills, S.T.

    1997-04-01

    The output radiation from the two-dimensional aperture of a semiconductor laser diode array is efficiently coupled into an optical fiber. The two-dimensional aperture is formed by stacking individual laser diode bars on top of another in a ``rack and stack`` configuration. Coupling into the fiber is then accomplished using individual microlenses to condition the output radiation of the laser diode bars. A lens that matches the divergence properties and wavefront characteristics of the laser light to the fiber optic is used to focus this conditioned radiation into the fiber. 3 figs.

  14. Fiber optic coupling of a microlens conditioned, stacked semiconductor laser diode array

    DOEpatents

    Beach, Raymond J.; Benett, William J.; Mills, Steven T.

    1997-01-01

    The output radiation from the two-dimensional aperture of a semiconductor laser diode array is efficiently coupled into an optical fiber. The two-dimensional aperture is formed by stacking individual laser diode bars on top of another in a "rack and stack" configuration. Coupling into the fiber is then accomplished using individual microlenses to condition the output radiation of the laser diode bars. A lens that matches the divergence properties and wavefront characteristics of the laser light to the fiber optic is used to focus this conditioned radiation into the fiber.

  15. Improved performance of high average power semiconductor arrays for applications in diode pumped solid state lasers

    SciTech Connect

    Beach, R.; Emanuel, M.; Benett, W.; Freitas, B.; Ciarlo, D.; Carlson, N.; Sutton, S.; Skidmore, J.; Solarz, R.

    1994-01-01

    The average power performance capability of semiconductor diode laser arrays has improved dramatically over the past several years. These performance improvements, combined with cost reductions pursued by LLNL and others in the fabrication and packaging of diode lasers, have continued to reduce the price per average watt of laser diode radiation. Presently, we are at the point where the manufacturers of commercial high average power solid state laser systems used in material processing applications can now seriously consider the replacement of their flashlamp pumps with laser diode pump sources. Additionally, a low cost technique developed and demonstrated at LLNL for optically conditioning the output radiation of diode laser arrays has enabled a new and scalable average power diode-end-pumping architecture that can be simply implemented in diode pumped solid state laser systems (DPSSL`s). This development allows the high average power DPSSL designer to look beyond the Nd ion for the first time. Along with high average power DPSSL`s which are appropriate for material processing applications, low and intermediate average power DPSSL`s are now realizable at low enough costs to be attractive for use in many medical, electronic, and lithographic applications.

  16. Optimization of J-V characteristic in diode array for phase change memory

    NASA Astrophysics Data System (ADS)

    Wang, Heng; Liu, Yan; Liu, Bo; Zhang, Chao; Song, Zhitang

    2016-10-01

    In this paper, current density-voltage (J-V) characteristic of dual trench diode array have been investigated by both TCAD model and experimental method. It is shown that the arsenic concentration in buried N+ layer (BNL), epitaxial (EPI) layer thickness, and the dosage of P region in PN junction are expected to be the prominent factors responsible for both of the leakage and drive current performance according to TCAD simulation. By introducing the optimal siliconbased results, the 4×4 diode arrays were successfully manufactured by 40nm CMOS technology. The median values of drive and reverse leakage current densities are 7.30×10-2 A/μm2 and 5.61×10-9 A/μm2, respectively. The breakdown voltages (BVDs) of diode array are exceeding 6V, and the Jon/Joff ratios of 109, which can satisfy the requirements of phase change memory (PCM) applications.

  17. Improving Reliability of High Power Quasi-CW Laser Diode Arrays Operating in Long Pulse Mode

    NASA Technical Reports Server (NTRS)

    Amzajerdian, Farzin; Meadows, Byron L.; Barnes, Bruce W.; Lockard, George E.; Singh, Upendra N.; Kavaya, Michael J.; Baker, Nathaniel R.

    2006-01-01

    Operating high power laser diode arrays in long pulse regime of about 1 msec, which is required for pumping 2-micron thulium and holmium-based lasers, greatly limits their useful lifetime. This paper describes performance of laser diode arrays operating in long pulse mode and presents experimental data of the active region temperature and pulse-to-pulse thermal cycling that are the primary cause of their premature failure and rapid degradation. This paper will then offer a viable approach for determining the optimum design and operational parameters leading to the maximum attainable lifetime.

  18. Improving lifetime of quasi-CW laser diode arrays for pumping 2-micron solid state lasers

    NASA Astrophysics Data System (ADS)

    Amzajerdian, Farzin; Meadows, Byron L.; Baker, Nathaniel R.; Barnes, Bruce W.; Singh, Upendra N.; Kavaya, Michael J.

    2007-04-01

    Operating high power laser diode arrays in long pulse regime of about 1 msec, which is required for pumping 2-micron thulium and holmium-based lasers, greatly limits their useful lifetime. This paper describes performance of laser diode arrays operating in long pulse mode and presents experimental data on the active region temperature and pulse-to-pulse thermal cycling that are the primary cause of their premature failure and rapid degradation. This paper will then offer a viable approach for determining the optimum design and operational parameters leading to the maximum attainable lifetime.

  19. Linear laser diode arrays for improvement in optical disk recording for space stations

    NASA Technical Reports Server (NTRS)

    Alphonse, G. A.; Carlin, D. B.; Connolly, J. C.

    1990-01-01

    The design and fabrication of individually addressable laser diode arrays for high performance magneto-optic recording systems are presented. Ten diode arrays with 30 mW cW light output, linear light vs. current characteristics and single longitudinal mode spectrum were fabricated using channel substrate planar (CSP) structures. Preliminary results on the inverse CSP structure, whose fabrication is less critically dependent on device parameters than the CSP, are also presented. The impact of systems parameters and requirements, in particular, the effect of feedback on laser design is assessed, and techniques to reduce feedback or minimize its effect on systems performance, including mode-stabilized structures, are evaluated.

  20. Improving Lifetime of Quasi-CW Laser Diode Arrays for Pumping 2-Micron Solid State Lasers

    NASA Technical Reports Server (NTRS)

    Amzajerdian, Farzin; Meadows, Byron L.; Baker, Nathaniel R.; Barnes, Bruce W.; Singh, Upendra N.; Kavaya, Michael J.

    2007-01-01

    Operating high power laser diode arrays in long pulse regime of about 1 msec, which is required for pumping 2-micron thulium and holmium-based lasers, greatly limits their useful lifetime. This paper describes performance of laser diode arrays operating in long pulse mode and presents experimental data on the active region temperature and pulse-to-pulse thermal cycling that are the primary cause of their premature failure and rapid degradation. This paper will then offer a viable approach for determining the optimum design and operational parameters leading to the maximum attainable lifetime.

  1. Detection of composite resin restorations using an ultraviolet light-emitting diode flashlight during forensic dental identification.

    PubMed

    Guzy, Gerald; Clayton, Mary Ann

    2013-06-01

    With the increased use of composite resin and the decreased use of amalgam as a dental restorative material, the forensic dental identification of unidentified human remains has become more difficult. Various methods have been used to detect the presence of composite resin restorations including dyes, forensic alternative light sources, quantitative light-induced fluorescence, and ultraviolet lights. Although these methods may be helpful, the expense of the equipment, the electrical requirements, and the need for water to wash the dye from the mouth may make these methods impractical especially in a temporary morgue situation during a mass disaster. The fluorescent properties of composite resins, when exposed to ultraviolet light, are well documented. Standard tube ultraviolet lights have been used to detect the presence of composite resin, but these lights are large and bulky, and the tubes are fragile. The development of ultraviolet light emitting diode flashlights has provided forensic odontologists with a tool that is small, inexpensive, and battery operated. The two forensic dental identification cases described here demonstrate the value of ultraviolet light emitting diode flashlights as an adjunct to a careful clinical and radiographic examination.

  2. Design and characterization of single photon avalanche diodes arrays

    NASA Astrophysics Data System (ADS)

    Neri, L.; Tudisco, S.; Lanzanò, L.; Musumeci, F.; Privitera, S.; Scordino, A.; Condorelli, G.; Fallica, G.; Mazzillo, M.; Sanfilippo, D.; Valvo, G.

    2010-05-01

    During the last years, in collaboration with ST-Microelectronics, we developed a new avalanche photo sensor, single photon avalanche diode (SPAD) see Ref.[S. Privitera, et al., Sensors 8 (2008) 4636 [1];S. Tudisco et al., IEEE Sensors Journal 8 (2008) 1324 [2

  3. Low absorption loss p-AlGaN superlattice cladding layer for current-injection deep ultraviolet laser diodes

    NASA Astrophysics Data System (ADS)

    Martens, M.; Kuhn, C.; Ziffer, E.; Simoneit, T.; Kueller, V.; Knauer, A.; Rass, J.; Wernicke, T.; Einfeldt, S.; Weyers, M.; Kneissl, M.

    2016-04-01

    Current injection into AlGaN-based laser diode structures with high aluminum mole fractions for deep ultraviolet emission is investigated. The electrical characteristics of laser diode structures with different p-AlGaN short period superlattice (SPSL) cladding layers with various aluminum mole fractions are compared. The heterostructures contain all elements that are needed for a current-injection laser diode including cladding and waveguide layers as well as an AlGaN quantum well active region emitting near 270 nm. We found that with increasing aluminum content in the p-AlGaN cladding, the diode turn-on voltage increases, while the series resistance slightly decreases. By introducing an SPSL instead of bulk layers, the operating voltage is significantly reduced. A gain guided broad area laser diode structure with transparent p-Al0.70Ga0.30N waveguide layers and a transparent p-cladding with an average aluminum content of 81% was designed for strong confinement of the transverse optical mode and low optical losses. Using an optimized SPSL, this diode could sustain current densities of more than 4.5 kA/cm2.

  4. A low-cost low-maintenance ultraviolet lithography light source based on light-emitting diodes.

    PubMed

    Erickstad, M; Gutierrez, E; Groisman, A

    2015-01-07

    A source of collimated ultraviolet (UV) light is a central piece of equipment needed for lithographic fabrication of microfluidic devices. Conventional UV light sources based on high-pressure mercury lamps require considerable maintenance and provide broad-band illumination with intensity that often changes with time. Here we present a source of narrow-band UV light based on an array of nine 365 nm light-emitting diodes (LEDs). Each LED has two dedicated converging lenses, reducing the divergence of light emanating from it to 5.4°. Partial overlap of the areas illuminated by individual LEDs provides UV illumination with a mean intensity of ~1.7 mW cm(-2) and coefficient of variation <3% over a 90 × 90 mm target area. The light source was used to lithographically fabricate micro-reliefs with thicknesses from ~25 to 311 μm with SU8 photoresists. A cumulative irradiation of 370 mJ cm(-2) (4 min exposure) produced reliefs of good quality for all SU8 thicknesses. Polydimethylsiloxane (PDMS) replicas of the SU8 reliefs had microchannels with nearly rectangular cross-sections that were highly consistent over the entire target area, and partitions between the channels had depth to width ratios up to 5. The UV light source has also been successfully used for photolithography with positive photoresists, AZ40XT and SPR-220. The proposed light source is built with a total cost of <$1000, consumes a minimal amount of power, is expected to last for ~50,000 exposures, is maintenance-free, and is particularly appealing for small research-and-development microfluidic fabrication.

  5. Coherent addition of high power laser diode array with a V-shape external Talbot cavity.

    PubMed

    Liu, B; Liu, Y; Braiman, Y

    2008-12-08

    We designed a V-shape external Talbot cavity for a broad-area laser diode array and demonstrated coherent laser beam combining at high power with narrow spectral linewidth. The V-shape external Talbot cavity provides good mode-discrimination and does not require a spatial filter. A multi-lobe far-field profile generated by a low filling-factor phase-locked array is confirmed by our numerical simulation.

  6. Point-of-use water disinfection using ultraviolet and visible light-emitting diodes.

    PubMed

    Lui, Gough Yumu; Roser, David; Corkish, Richard; Ashbolt, Nicholas J; Stuetz, Richard

    2016-05-15

    Improvements in point-of-use (POU) drinking water disinfection technologies for remote and regional communities are urgently needed. Conceptually, UV-C light-emitting diodes (LEDs) overcome many drawbacks of low-pressure mercury tube based UV devices, and UV-A or visible light LEDs also show potential. To realistically evaluate the promise of LED disinfection, our study assessed the performance of a model 1.3 L reactor, similar in size to solar disinfection bottles. In all, 12 different commercial or semi-commercial LED arrays (270-740 nm) were compared for their ability to inactivate Escherichia coli K12 ATCC W3110 and Enterococcus faecalis ATCC 19433 over 6h. Five log10 and greater reductions were consistently achieved using the 270, 365, 385 and 405 nm arrays. The output of the 310 nm array was insufficient for useful disinfection while 430 and 455 nm performance was marginal (≈ 4.2 and 2.3-log10s E. coli and E. faecalis over the 6h). No significant disinfection was observed with the 525, 590, 623, 660 and 740 nm arrays. Delays in log-phase inactivation of E. coli were observed, particularly with UV-A wavelengths. The radiation doses required for >3-log10 reduction of E. coli and E. faecalis differed by 10 fold at 270 nm but only 1.5-2.5 fold at 365-455 nm. Action spectra, consistent with the literature, were observed with both indicators. The design process revealed cost and technical constraints pertaining to LED electrical efficiency, availability and lifetime. We concluded that POU LED disinfection using existing LED technology is already technically possible. UV-C LEDs offer speed and energy demand advantages, while UV-A/violet units are safer. Both approaches still require further costing and engineering development. Our study provides data needed for such work.

  7. Digital radiography of the chest by self-scanning linear diode arrays.

    PubMed

    Slasky, B S; Sashin, D; Horton, J A; Sternglass, E J; Bron, K M; Deutsch, M; Herron, J M; Kennedy, W H; Boyer, J W; Girdany, B R

    1987-01-01

    Diode array digital radiography DADR is a method of radiographic imaging that combines the advantages of computer technology with self-scanning linear diode arrays. These digital images are superior to those obtained by film in recording and displaying information in the lightest and the darkest areas of the film, resulting in a balanced image of the entire thorax without compromising detail, and at reduced radiation dose. This is a direct result of the wide dynamic range, high contrast sensitivity, fiber optic coupling, small diode size, short exposure time, and rejection of scattered x-rays of the system coupled with digital post-processing enhancement of the image displayed at 1024 X 1024 pixels.

  8. Semiconductor laser diode array characterization by means of field intensity measurements

    NASA Astrophysics Data System (ADS)

    Zeni, Luigi; Cutolo, Antonello; Pierri, Rocco

    1999-04-01

    Semiconductor laser diode arrays are becoming a widespread source for a large variety of applications, ranging from telecommunications to industry. In particular, the availability of low-cost high-power laser diode arrays makes it possible their use in industrial context for material cutting, welding, diagnostics and processing. In the above applications the exact control of the beam quality plays a very important role because it directly affects the reliability of the final result. We have developed a characterization technique which, starting from total intensity measurements on planes orthogonal to the beam propagation path, is able to deduce the working conditions of each laser setting up the array. The importance of this approach is twofold. First it allows a non destructive quality control on ready-to-use laser arrays; second it may represent a powerful tool for the detection of design problems in the array itself and in the bias circuitry as well. The problem is formulated as an inverse one and the solution is found by minimizing a proper functional. Several numerical experiments have been performed and the results clearly indicate the ability of the proposed approach tin identifying specific failures in a laser diode array, such as single element power drop.

  9. High power, high efficiency, 2D laser diode arrays for pumping solid state lasers

    SciTech Connect

    Rosenberg, A.; McShea, J.C.; Bogdan, A.R.; Petheram, J.C.; Rosen, A.

    1987-11-01

    This document reports the current performance of 2D laser diode arrays operating at 770 nm and 808 nm for pumping promethium and neodymium solid state lasers, respectively. Typical power densities are in excess of 2kw/cm/sup 2/ with overall efficiencies greater than 30%.

  10. Tunnel-injection GaN quantum dot ultraviolet light-emitting diodes

    SciTech Connect

    Verma, Jai; Kandaswamy, Prem Kumar; Protasenko, Vladimir; Verma, Amit; Grace Xing, Huili; Jena, Debdeep

    2013-01-28

    We demonstrate a GaN quantum dot ultraviolet light-emitting diode that uses tunnel injection of carriers through AlN barriers into the active region. The quantum dot heterostructure is grown by molecular beam epitaxy on AlN templates. The large lattice mismatch between GaN and AlN favors the formation of GaN quantum dots in the Stranski-Krastanov growth mode. Carrier injection by tunneling can mitigate losses incurred in hot-carrier injection in light emitting heterostructures. To achieve tunnel injection, relatively low composition AlGaN is used for n- and p-type layers to simultaneously take advantage of effective band alignment and efficient doping. The small height of the quantum dots results in short-wavelength emission and are simultaneously an effective tool to fight the reduction of oscillator strength from quantum-confined Stark effect due to polarization fields. The strong quantum confinement results in room-temperature electroluminescence peaks at 261 and 340 nm, well above the 365 nm bandgap of bulk GaN. The demonstration opens the doorway to exploit many varied features of quantum dot physics to realize high-efficiency short-wavelength light sources.

  11. High performance near-ultraviolet flip-chip light-emitting diodes with distributed Bragg reflector

    NASA Astrophysics Data System (ADS)

    Choi, Il-Gyun; Jin, Geun-Mo; Park, Jun-Cheon; Jeon, Soo-Kun; Park, Eun-Hyun

    2015-09-01

    We have fabricated the near-ultraviolet (NUV) flip-chip (FC) light-emitting diodes (LEDs) with the high external quantum efficiency (EQE) using distributed Bragg reflectors (DBRs) and compared with conventional FC-LED using silver (Ag) reflector. Reflectance of Ag is very high (90 ~ 95 %) at visible spectrum region, but sharply decrease at NUV region. Therefore we used DBR composed of two different materials which have high-index contrast, such as TiO2 and SiO2. However, to achieve high-performance NUV flip-chip LEDs, we used Ta2O5 instead of TiO2 that absorbs lights of NUV region. Thus, we have designed a DBR composed of twenty pairs of Ta2O5 and SiO2 using optical coating design software. The DBR designed by our group achieves a reflectance of ~99 % in the NUV region (350 ~ 500 nm), which is much better than Ag reflector. Optical power is higher than the Ag-LED up to 22 % @ 390 nm.

  12. Development of substrate-removal-free vertical ultraviolet light-emitting diode (RefV-LED)

    SciTech Connect

    Kurose, N. Aoyagi, Y.; Shibano, K.; Araki, T.

    2014-02-15

    A vertical ultraviolet (UV) light-emitting diode (LED) that does not require substrate removal is developed. Spontaneous via holes are formed in n-AlN layer epitaxially grown on a high conductive n+Si substrate and the injected current flows directly from the p-electrode to high doped n{sup +} Si substrate through p-AlGaN, multi-quantum wells, n-AlGaN and spontaneous via holes in n-AlN. The spontaneous via holes were formed by controlling feeding-sequence of metal-organic gas sources and NH{sub 3} and growth temperature in MOCVD. The via holes make insulating n-AlN to be conductive. We measured the current-voltage, current-light intensity and emission characteristics of this device. It exhibited a built-in voltage of 3.8 V and emission was stated at 350 nm from quantum wells with successive emission centered at 400 nm. This UV LED can be produced, including formation of n and p electrodes, without any resist process.

  13. NANOSTRUCTURED HIGH PERFORMANCE ULTRAVIOLET AND BLUE LIGHT EMITTING DIODES FOR SOLID STATE LIGHTING

    SciTech Connect

    Arto V. Nurmikko; Jung Han

    2004-10-01

    We report on research results in this project which synergize advanced material science approaches with fundamental optical physics concepts pertaining to light-matter interaction, with the goal of solving seminal problems for the development of very high performance light emitting diodes (LEDs) in the blue and near ultraviolet for Solid State Lighting applications. Accomplishments in the first 12 month contract period include (1) new means of synthesizing zero- and one-dimensional GaN nanostructures, (2) establishment of the building blocks for making GaN-based microcavity devices, and (3) demonstration of top-down approach to nano-scale photonic devices for enhanced spontaneous emission and light extraction. These include a demonstration of eight-fold enhancement of the external emission efficiency in new InGaN QW photonic crystal structures. The body of results is presented in this report shows how a solid foundation has been laid, with several noticeable accomplishments, for innovative research, consistent with the stated milestones.

  14. High-Power Genuine Ultraviolet Light-Emitting Diodes Based On Colloidal Nanocrystal Quantum Dots.

    PubMed

    Kwak, Jeonghun; Lim, Jaehoon; Park, Myeongjin; Lee, Seonghoon; Char, Kookheon; Lee, Changhee

    2015-06-10

    Thin-film ultraviolet (UV) light-emitting diodes (LEDs) with emission wavelengths below 400 nm are emerging as promising light sources for various purposes, from our daily lives to industrial applications. However, current thin-film UV-emitting devices radiate not only UV light but also visible light. Here, we introduce genuine UV-emitting colloidal nanocrystal quantum dot (NQD) LEDs (QLEDs) using precisely controlled NQDs consisting of a 2.5-nm-sized CdZnS ternary core and a ZnS shell. The effective core size is further reduced during the shell growth via the atomic diffusion of interior Cd atoms to the exterior ZnS shell, compensating for the photoluminescence red shift. This design enables us to develop CdZnS@ZnS UV QLEDs with pure UV emission and minimal parasitic peaks. The irradiance is as high as 2.0-13.9 mW cm(-2) at the peak wavelengths of 377-390 nm, several orders of magnitude higher than that of other thin-film UV LEDs.

  15. A Lunar Optical-Ultraviolet-Infrared Synthesis Array (LOUISA)

    NASA Technical Reports Server (NTRS)

    Burns, Jack O. (Editor); Johnson, Stewart W. (Editor); Duric, Nebojsa (Editor)

    1992-01-01

    This document contains papers presented at a workshop held to consider 'optical ultraviolet infrared' interferometric observations from the moon. Part 1 is an introduction. Part 2 is a description of current and planned ground-based interferometers. Part 3 is a description of potential space-based interferometers. Part 4 addresses the potential for interferometry on the moon. Part 5 is the report of the workshop's working groups. Concluding remarks, summary, and conclusions are presented in Part 6.

  16. Investigation of Luminescent Diode Arrays for Photochromic Film Recording

    DTIC Science & Technology

    1969-06-30

    size or the multi-element diode is expoised. The density chat e anj discussed above may require monitoring at the beginning and end of the -rocass...GT thermal f~ux depression factor of the irradiation T capsule resonance absorption integral (in the neutron energy range of 0.3 to 1 ev) of gallium...8217n die geometry. If one d.-notes this inverse flux depression factor by 1/’ one obtains the valued of .55 for a 45 mil spaclng ari .50 for a 30 mril

  17. Multilayer mirror and foil filter AXUV diode arrays on CDX-U spherical torus

    NASA Astrophysics Data System (ADS)

    Soukhanovskii, V. A.; Stutman, D.; Iovea, M.; Finkenthal, M.; Moos, H. W.; Munsat, T.; Jones, B.; Hoffman, D.; Kaita, R.; Majeski, R.

    2001-01-01

    Recent upgrades to CDX-U spherical torus diagnostics include two 10-channel AXUV diode arrays. The multilayer mirror (MLM) array measures the λ150 O VI brightness profile in the poloidal plane using the Mo/B4C synthetic multilayer structures as dispersive elements. The foil filter array has a tangential view and is equipped with interchangeable clear aperture, beryllium and titanium filters. This allows measurements of radiated power, O VI or C V radial distributions, respectively. The O VI and C V emissivity and the radiated power profiles are highly peaked. A Neoclassical impurity accumulation mechanism is considered as an explanation. For radiated power measurements in the Te⩽100 eV plasmas, photon energy dependent corrections must be used in order to account for nonlinear AXUV sensitivity in the range Ephot⩽20 eV. The arrays are also used for characterization of resistive MHD phenomena, such as the low m modes, saw-tooth oscillations and internal reconnection events. Based on the successful operation of the diagnostics, a new ultra soft x-ray multilayer mirror diode AXUV diode array monitoring the 34 Å emissivity distribution of C VI will be built and installed on the National Spherical Torus Experiment.

  18. An imaging diode array soft x-ray diagnostic for Z (abstract)

    NASA Astrophysics Data System (ADS)

    Simpson, W. W.; Porter, J. L.; Ruggles, L. E.; Wenger, D. F.

    2001-01-01

    Measurements of the hohlraum wall temperature in Z-pinch driven hohlraum experiments require looking through small (2-4 mm diameter) diagnostic holes that undergo some degree of hole closure. The existing soft x-ray diagnostics on Z measure the total flux exiting this diagnostic hole and are therefore affected by this hole closure. To avoid having to measure the effective diagnostic hole area we have designed and constructed an imaging diode array (IDA) that incorporates pinhole imaging and an array of filtered silicon diodes to measure the absolute x-ray intensity from a spatially resolved region of a target. The instrument uses silicon diodes with subnanosecond time response that are sensitive to soft x rays in the range 100-3000 eV. An image of the target area is projected onto the silicon diodes using pinholes. Between each pinhole and it's respective diode is a soft x-ray filter. The material and thickness of the filter are selected to allow unfolding of spectral information in the 100-3000 eV spectral region. We plan to insert a set of grazing-incidence mirrors between each of the filter/diode pairs in a future version of this instrument to better define the spectral bandpass of each diode channel. Radiation from the target region is monitored by a gated microchannel-plate-intensified image recording device that is located immediately behind the diode array. A small shadow in the recorded image corresponds to the specific area of the target that is imaged onto each silicon diode. We are presently fielding this instrument in experiments on the Z facility located at Sandia National Laboratories in Albuquerque, NM. The instrument is located on the same line-of-sight and measures the same spatial region as a filtered fast-framing x-ray pinhole camera and a transmission grating spectrometer. This article describes the design of the IDA diagnostic and presents the results of measurements obtained in hohlraum experiments conducted on Z.

  19. Wavelength tunable, 264 J laser diode array for 10 Hz/1ms Yb:YAG pumping

    NASA Astrophysics Data System (ADS)

    Chanteloup, J.-C.; Albach, D.; Assémat, F.; Bahbah, S.; Bourdet, G.; Piatti, P.; Pluvinage, M.; Vincent, B.; LeTouzé, G.; Mattern, T.; Biesenbach, J.; Müntz, H.; Noeske, A.; Venohr, R.

    2008-05-01

    The Lucia [1,2] Laser program, under development at the LULI laboratory, aims at delivering a 1030 nm, 100J, 10 Hz, 10 ns pulse train. The two laser heads used in the amplification stage relies on water-cooled mm-thick Yb:YAG disks, each of them pumped by a 34×13 cm2 Laser Diode Array (LDA). For each LDA, the 88 QCW diodes stacks manufactured by DILAS GmbH will be tiled in an 8×11 arrangement. Fine wavelength tuning is performed through bias current adjustment, water temperature control and conductivity adjustment. Wavelength homogeneity experimental verification has been validated.

  20. Generation of blue light by sum-frequency generation of a spectrally combined broad-area diode laser array.

    PubMed

    Zhu, Zhanda; Jiang, Menghua; Yu, Haoyang; Hui, Yongling; Lei, Hong; Li, Qiang

    2016-10-15

    We present the first demonstration of a spectrally beam combined diode laser array with subsequent sum-frequency generation (SFG). The combined beam of the diode laser array with 19 emitters has the same beam quality as a single emitter, and the wavelength of each emitter is different. The blue light is generated by sum-frequency mixing of pairs of emitters in the diode laser array. About 93 mW of blue light power is produced using a PPLN crystal. Compared with the SFG of two emitters, this approach can increase the number of lasers participating in nonlinear frequency conversion. Thus, it can enhance the available power.

  1. Qualification Testing of Laser Diode Pump Arrays for a Space-Based 2-micron Coherent Doppler Lidar

    NASA Technical Reports Server (NTRS)

    Amzajerdian, Farzin; Meadows, Byron L.; Baker, Nathaniel R.; Barnes, Bruce W.; Singh, Upendra N.; Kavaya, Michael J.

    2007-01-01

    The 2-micron thulium and holmium-based lasers being considered as the transmitter source for space-based coherent Doppler lidar require high power laser diode pump arrays operating in a long pulse regime of about 1 msec. Operating laser diode arrays over such long pulses drastically impact their useful lifetime due to the excessive localized heating and substantial pulse-to-pulse thermal cycling of their active regions. This paper describes the long pulse performance of laser diode arrays and their critical thermal characteristics. A viable approach is then offered that allows for determining the optimum operational parameters leading to the maximum attainable lifetime.

  2. Hard solder 20-kW QCW stack array diode laser

    NASA Astrophysics Data System (ADS)

    Li, Xiaoning; Kang, Lijun; Wang, Jingwei; Zhang, Pu; Xiong, Lingling; Liu, Xingsheng

    2012-03-01

    With the increasing applications of high power semiconductor lasers in industry, advanced manufacturing, aerospace, medical systems, display, entertainment, etc., semiconductor lasers with high power and high performances are required. The performance of semiconductor lasers is greatly affected by packaging structure, packaging process and beam shaping. A novel macro channel cooler (MaCC) for stack array laser with good heat dissipation capacity and high reliability is presented in this work. Based on the MaCC package, a high power stack array diode laser is successfully fabricated. A series of techniques such as spectrum control and beam control are used to achieve narrow spectrum and high beam quality. The performances of the semiconductor laser stack array are characterized. A high power 20kW QCW hard solder packaged stack array laser is fabricated; a narrow spectrum of 3.94 nm and an excellent rectangular beam shape are obtained. The lifetime of the stack array laser is tested as well.

  3. Rapid prototyping process using linear array of high-power laser diodes

    NASA Astrophysics Data System (ADS)

    Zhu, Linquan; Cheng, Jun; Zhou, Hanchang

    2000-02-01

    Because of the weak points of the SLS spot Scanning process, a new rapid prototyping process -- SLS line scan using linear array of high power laser diodes regarded as energy sources is researched in this paper. A linear array with requisite length is formed by some high power laser diodes that can be derived individually. Beams of the linear array are transferred to the workplace and imaged some short and light lines by the corresponding optical collimators. They are lined up in a linear laser beam without separation whose length is equal to that of the linear array diodes. When sintering powdered material, the linear laser beam scans in one direction along x axis only. Only if the maximum line length is less than the y axial size of the workpiece, it is necessary that linear laser beam is lapped for some times in the y axis. The Scanning mode of x-y simultaneous guideways are used in this new system which differs entirely from the vibrating mirror scan. The scanning trace of the latter is an arc that will influence processing quality. This new process has higher efficiency and better quality than the traditional spot scanning method.

  4. Progress of laser diode arrays operating under harsh conditions

    NASA Astrophysics Data System (ADS)

    Kohl, Andreas; Fillardet, Thierry; Moisan, Herve; Brousse, Eric

    2010-10-01

    High Power Laser Diodes (HPLD) are increasingly used in different fields of applications such as Industry, Medical and Defense. Significant improvements of performances (especially in efficiency) and a reproducible manufacturing process have led to reliable, highly robust components. For defense and security applications these devices are used predominantly for pumping of solid state lasers (range finders, designators and countermeasures) but also as direct light source (illuminator, pointer,...). For these applications the devices not only have to show outstanding electro optical performances but the packaging must also be robust enough to sustain the harsh environmental requirements. Due to recent progress in both semiconductor technology and packaging, QLD was able to push the peak power up to 400W per bar at 808nm. At this wavelength QLD has achieved record high efficiencies close to 65% in production. Thanks to a very small bar to bar pitch down to 330μm our stacks deliver peak power densities as high as 12 kW/cm². Even at 400 μm pitch the bars can be collimated in order to improve the beam quality.

  5. Detection and modeling of leakage current in AlGaN-based deep ultraviolet light-emitting diodes

    SciTech Connect

    Moseley, Michael William; Allerman, Andrew A.; Crawford, Mary H.; Wierer, Jonathan; Smith, Michael L.; Armstrong, Andrew

    2015-03-01

    Current-voltage (IV) characteristics of two AlGaN-based deep ultraviolet (DUV) light-emitting diodes (LEDs) with differing densities of open-core threading dislocations (nanopipes) are analyzed. A three-diode circuit is simulated to emulate the IV characteristics of the DUV-LEDs, but is only able to accurately model the lower leakage current, lower nanopipe density DUV-LED. It was found that current leakage through the nanopipes in these structures is rectifying, despite nanopipes being previously established as inherently n-type. Using defect-sensitive etching, the nanopipes are revealed to terminate within the p-type GaN capping layer of the DUV-LEDs. The circuit model is modified to account for another p-n junction between the n-type nanopipes and the p-type GaN, and an excellent fit to the IV characteristics of the leaky DUV-LED is achieved.

  6. Optimization of rod diameter in solid state lasers side pumped with multiple laser diode arrays

    NASA Technical Reports Server (NTRS)

    Sims, Newton, Jr.; Chamblee, Christyl M.; Barnes, Norman P.; Lockard, George E.; Cross, Patricia L.

    1992-01-01

    Results of a study to determine the optimum laser rod diameter for maximum output energy in a solid state neodymium laser transversely pumped with multiple laser diode arrays are reported here. Experiments were performed with 1.0 mm, 1.5 mm and 2.0 mm rod radii of both neodymium doped Y3Al5O12 (Nd:YAG) and La2Be2O5 (Nd:BeL) pumped with laser diode arrays having a maximum combined energy of 10.5 mJ. Equations were derived which predict the optimum rod radius and corresponding output mirror reflectivity for a given laser material and total pump energy. Predictions of the equations agreed well with the experiments for each of the laser materials which possessed significantly different laser properties from one another.

  7. Pinning, flux diodes and ratchets for vortices interacting with conformal pinning arrays

    SciTech Connect

    Olson Reichhardt, Cynthia Jane; Wang, Y. L.; Xiao, Z. L.; Kwok, W. K.; Ray, Dipanjan; Reichhardt, Charles; Jankó, B.

    2016-05-31

    A conformal pinning array can be created by conformally transforming a uniform triangular pinning lattice to produce a new structure in which the six-fold ordering of the original lattice is conserved but where there is a spatial gradient in the density of pinning sites. Here we examine several aspects of vortices interacting with conformal pinning arrays and how they can be used to create a flux flow diode effect for driving vortices in different directions across the arrays. Under the application of an ac drive, a pronounced vortex ratchet effect occurs where the vortices flow in the easy direction of the array asymmetry. When the ac drive is applied perpendicular to the asymmetry direction of the array, it is possible to realize a transverse vortex ratchet effect where there is a generation of a dc flow of vortices perpendicular to the ac drive due to the creation of a noise correlation ratchet by the plastic motion of the vortices. We also examine vortex transport in experiments and compare the pinning effectiveness of conformal arrays to uniform triangular pinning arrays. In conclusion, we find that a triangular array generally pins the vortices more effectively at the first matching field and below, while the conformal array is more effective at higher fields where interstitial vortex flow occurs.

  8. Pinning, flux diodes and ratchets for vortices interacting with conformal pinning arrays

    DOE PAGES

    Olson Reichhardt, C. J.; Wang, Y. L.; Xiao, Z. L.; ...

    2017-02-01

    A conformal pinning array can be created by conformally transforming a uniform triangular pinning lattice to produce a new structure in which the six-fold ordering of the original lattice is conserved but where there is a spatial gradient in the density of pinning sites. Here we examine several aspects of vortices interacting with conformal pinning arrays and how they can be used to create a flux flow diode effect for driving vortices in different directions across the arrays. Under the application of an ac drive, a pronounced vortex ratchet effect occurs where the vortices flow in the easy direction ofmore » the array asymmetry. When the ac drive is applied perpendicular to the asymmetry direction of the array, it is possible to realize a transverse vortex ratchet effect where there is a generation of a dc flow of vortices perpendicular to the ac drive due to the creation of a noise correlation ratchet by the plastic motion of the vortices. We also examine vortex transport in experiments and compare the pinning effectiveness of conformal arrays to uniform triangular pinning arrays. In conclusion, we find that a triangular array generally pins the vortices more effectively at the first matching field and below, while the conformal array is more effective at higher fields where interstitial vortex flow occurs.« less

  9. Pinning, flux diodes and ratchets for vortices interacting with conformal pinning arrays

    NASA Astrophysics Data System (ADS)

    Olson Reichhardt, C. J.; Wang, Y. L.; Xiao, Z. L.; Kwok, W. K.; Ray, D.; Reichhardt, C.; Jankó, B.

    2017-02-01

    A conformal pinning array can be created by conformally transforming a uniform triangular pinning lattice to produce a new structure in which the six-fold ordering of the original lattice is conserved but where there is a spatial gradient in the density of pinning sites. Here we examine several aspects of vortices interacting with conformal pinning arrays and how they can be used to create a flux flow diode effect for driving vortices in different directions across the arrays. Under the application of an ac drive, a pronounced vortex ratchet effect occurs where the vortices flow in the easy direction of the array asymmetry. When the ac drive is applied perpendicular to the asymmetry direction of the array, it is possible to realize a transverse vortex ratchet effect where there is a generation of a dc flow of vortices perpendicular to the ac drive due to the creation of a noise correlation ratchet by the plastic motion of the vortices. We also examine vortex transport in experiments and compare the pinning effectiveness of conformal arrays to uniform triangular pinning arrays. We find that a triangular array generally pins the vortices more effectively at the first matching field and below, while the conformal array is more effective at higher fields where interstitial vortex flow occurs.

  10. Near ultraviolet light emitting diodes using ZnMgO:N/ZnO hetero-junction grown by MOVPE

    NASA Astrophysics Data System (ADS)

    Fujita, Yasuhisa; Yanase, Shogo; Nishikori, Hirokazu; Hiragino, Yuto; Furubayashi, Yutaka; Lin, Jie; Yoshida, Toshiyuki

    2017-04-01

    A ZnMgO:N/ZnO/ZnO:Ga single hetero-junction light emitting diode structure on Al2O3 (11 2 ̅0) substrate was fabricated by metalorganic vapor phase epitaxy. By using ZnMgO:N as a substitute for a ZnO:N top layer of a homojunction LED, improved rectifying current-voltage characteristics were obtained. Although the device had a heating problem and the luminescent area was partly in the ZnMgO:N layer, a sharp ultraviolet electroluminescence emission at 3.17 eV was successfully observed at room temperature.

  11. Indium Tin Oxide-Free Transparent Conductive Electrode for GaN-Based Ultraviolet Light-Emitting Diodes.

    PubMed

    Kim, Ja-Yeon; Jeon, Jong-Hyun; Kwon, Min-Ki

    2015-04-22

    Transparent conducting electrodes are important components of highly efficient ultraviolet light-emitting diodes (UV LEDs). Indium tin oxide (ITO) is commonly used to form a current spreading layer, but its UV-range optical transparency is limited with a low sheet resistance. We demonstrate a simple solution-based coating technique to obtain large-area, highly uniform, and conductive silver-nanowire-based electrodes that exhibit UV-range optical transparency better than that of ITO for the same sheet resistance. The UV LEDs fabricated using this current spreading layer showed improved optical power emission as well as improvement in electrical properties.

  12. Adapting the waterproof BMS-96 diode array for isodose determination of dynamic beams.

    PubMed

    Muren, L P; Hafslund, R; Valen, H; Schuster, G; Dahl, O

    2000-01-01

    We report the application of the Schuster BMS-96 waterproof linear diode array for isodose determination of dynamic beams. The array recorded beam profiles correctly, while depth dose distributions of dynamic beams with large variations in dose rate were registered erroneously. The deviations could be eliminated by appropriate software modifications. Until the software is revised, true isodoses can be obtained by rescaling each individual profile to the depth dose curve as measured with a single ionization chamber. After the corrections presented in the paper, isodoses interpolated from these corrected data sets agreed with ionization chamber measurements within 1-2%.

  13. Dynamic characteristics of far-field radiation of current modulated phase-locked diode laser arrays

    NASA Technical Reports Server (NTRS)

    Elliott, R. A.; Hartnett, K.

    1987-01-01

    A versatile and powerful streak camera/frame grabber system for studying the evolution of the near and far field radiation patterns of diode lasers was assembled and tested. Software needed to analyze and display the data acquired with the steak camera/frame grabber system was written and the total package used to record and perform preliminary analyses on the behavior of two types of laser, a ten emitter gain guided array and a flared waveguide Y-coupled array. Examples of the information which can be gathered with this system are presented.

  14. Innovative techniques for the production of low cost 2D laser diode arrays

    NASA Astrophysics Data System (ADS)

    1990-05-01

    The objective of this program was to develop a low cost fabrication method for high performance laser diode arrays. The program focussed on reliable and cost effective ways to grow, assemble and test diode bars of molecular beam epitaxy material. Quantum well laser structures were grown on 2 and 3 GaAs substrates. These wafers were photolithographically processed, scribed into bars, and the bars assembled by various techniques. The assemblies were tested for performance, reproducibility, and reliability. The originally proposed assembly, a grooved BeO block, was evaluated and abandoned as unreliable. However, a simplified bar and individual BeO substrate assembly method was developed, and state of the art results achieved on robust 1 cm linear diode arrays, which survived repeated high power testing to power level in excess of 80 watts/bar. This method may be scaled up for multiple bar assemblies without additional complexity by adding laser bars and BeO spacers as required. The BeO sub-mounts are coated prior to assembly in such a fashion to provide a low resistance series connection to each bar in the array, similar to the grooved substrate series connection geometry.

  15. Feasibility of Ultraviolet Light Emitting Diodes as an Alternative Light Source for Photocatalysis

    NASA Technical Reports Server (NTRS)

    Levine, Langanf H.; Richards, Jeffrey T.; Soler, Robert; Maxik, Fred; Coutts, Janelle; Wheeler, Raymond M.

    2011-01-01

    The objective of this study was to determine whether ultraviolet light emitting diodes (UV-LEDs) could serve as an alternative photon source efficiently for heterogeneous photocatalytic oxidation (PCO). An LED module consisting of 12 high-power UV-A LEDs was designed to be interchangeable with a UV-A fluorescent black light blue (BLB) lamp in a Silica-Titania Composite (STC) packed bed annular reactor. Lighting and thermal properties were characterized to assess the uniformity and total irradiant output. A forward current of (I(sub F)) 100 mA delivered an average irradiance of 4.0 m W cm(exp -2), which is equivalent to the maximum output of the BLB, but the irradiance of the LED module was less uniform than that of the BLB. The LED- and BLB-reactors were tested for the oxidization of 50 ppmv ethanol in a continuous flow-through mode with 0.94 sec space time. At the same irradiance, the UV-A LED reactor resulted in a lower PCO rate constant than the UV-A BLB reactor (19.8 vs. 28.6 nM CO2 sec-I), and consequently lower ethanol removal (80% vs. 91%) and mineralization efficiency (28% vs. 44%). Ethanol mineralization increased in direct proportion to the irradiance at the catalyst surface. This result suggests that reduced ethanol mineralization in the LED- reactor could be traced to uneven irradiance over the photocatalyst, leaving a portion of the catalyst was under-irradiated. The potential of UV-A LEDs may be fully realized by optimizing the light distribution over the catalyst and utilizing their instantaneous "on" and "off' feature for periodic irradiation. Nevertheless, the current UV-A LED module had the same wall plug efficiency (WPE) of 13% as that of the UV-A BLB. These results demonstrated that UV-A LEDs are a viable photon source both in terms of WPE and PCO efficiency.

  16. Development of ultraviolet electroabsorption modulators and light emitting diodes based on AlGaN alloys

    NASA Astrophysics Data System (ADS)

    Kao, Chen-Kai

    The research in this dissertation addressed the development of ultraviolet (UV) electroabsorption modulators and ultraviolet light emitting diodes (UV-LEDs), covering the spectral range from 360 to 265 nm. The materials system for both types of devices is the AlGaN alloys, either in bulk or quantum well (QW) form, grown by plasma-assisted molecular beam epitaxy (MBE). Potential applications of these devices either individually or in combination include UV non-line-of-sight free-space-optical communications, UV sensing and spectroscopic systems, Q-switched pulsed lasers, water/air purification and various medical applications. Optical modulators based on cubic III-V semiconductors have been the subject of extensive research over the past several years. Such devices are typically based on the quantum-confined Stark effect to modify the absorption spectrum of multiple-quantum-well active regions. On the other hand, in wurtzite III-Nitride semiconductors, strong electric fields are already present in the quantum wells due to intrinsic and piezoelectric polarizations; as a result, an even greater change in absorption is achievable, especially if the internal fields are compensated by the external bias so that the net field in the quantum wells is reduced. A number of UV electroabsorption modulators based on Schottky barriers on bulk GaN and GaN /AlGaN multiple quantum wells (MQWs) were designed, fabricated and characterized. Record modulation ratio of 30 % was obtained from bulk GaN Schottky barrier modulators at the excitonic resonant energy of 3.45 eV (360 nm) upon the application of 12 V reverse bias. Similarly, record modulation ratio of 43% was obtained from GaN / AlGaN MQWs Schottky barrier modulators at the excitonic resonant energy of 3.48 eV (356 nm) upon the application of 17 V reverse bias. The external quantum efficiency (EQE) of AlGaN based deep UV LEDS is relatively low (˜1% at 270 nm). This is generally attributed to the poor internal quantum efficiency

  17. Robotic radiosurgery system patient-specific QA for extracranial treatments using the planar ion chamber array and the cylindrical diode array.

    PubMed

    Lin, Mu-Han; Veltchev, Iavor; Koren, Sion; Ma, Charlie; Li, Jinsgeng

    2015-07-08

    Robotic radiosurgery system has been increasingly employed for extracranial treatments. This work is aimed to study the feasibility of a cylindrical diode array and a planar ion chamber array for patient-specific QA with this robotic radiosurgery system and compare their performance. Fiducial markers were implanted in both systems to enable image-based setup. An in-house program was developed to postprocess the movie file of the measurements and apply the beam-by-beam angular corrections for both systems. The impact of noncoplanar delivery was then assessed by evaluating the angles created by the incident beams with respect to the two detector arrangements and cross-comparing the planned dose distribution to the measured ones with/without the angular corrections. The sensitivity of detecting the translational (1-3 mm) and the rotational (1°-3°) delivery errors were also evaluated for both systems. Six extracranial patient plans (PTV 7-137 cm³) were measured with these two systems and compared with the calculated doses. The plan dose distributions were calculated with ray-tracing and the Monte Carlo (MC) method, respectively. With 0.8 by 0.8 mm² diodes, the output factors measured with the cylindrical diode array agree better with the commissioning data. The maximum angular correction for a given beam is 8.2% for the planar ion chamber array and 2.4% for the cylindrical diode array. The two systems demonstrate a comparable sensitivity of detecting the translational targeting errors, while the cylindrical diode array is more sensitive to the rotational targeting error. The MC method is necessary for dose calculations in the cylindrical diode array phantom because the ray-tracing algorithm fails to handle the high-Z diodes and the acrylic phantom. For all the patient plans, the cylindrical diode array/ planar ion chamber array demonstrate 100% / > 92% (3%/3 mm) and > 96% / ~ 80% (2%/2 mm) passing rates. The feasibility of using both systems for robotic

  18. Robotic radiosurgery system patient-specific QA for extracranial treatments using the planar ion chamber array and the cylindrical diode array.

    PubMed

    Lin, Mu-Han; Veltchev, Iavor; Koren, Sion; Ma, Charlie; Li, Jinsgeng

    2015-07-01

    Robotic radiosurgery system has been increasingly employed for extracranial treatments. This work is aimed to study the feasibility of a cylindrical diode array and a planar ion chamber array for patient-specific QA with this robotic radiosurgery system and compare their performance. Fiducial markers were implanted in both systems to enable image-based setup. An in-house program was developed to postprocess the movie file of the measurements and apply the beam-by-beam angular corrections for both systems. The impact of noncoplanar delivery was then assessed by evaluating the angles created by the incident beams with respect to the two detector arrangements and cross-comparing the planned dose distribution to the measured ones with/without the angular corrections. The sensitivity of detecting the translational (1-3 mm) and the rotational (1°-3°) delivery errors were also evaluated for both systems. Six extracranial patient plans (PTV 7-137 cm(3)) were measured with these two systems and compared with the calculated doses. The plan dose distributions were calculated with ray-tracing and the Monte Carlo (MC) method, respectively. With 0.8 by 0.8 mm(2) diodes, the output factors measured with the cylindrical diode array agree better with the commissioning data. The maximum angular correction for a given beam is 8.2% for the planar ion chamber array and 2.4% for the cylindrical diode array. The two systems demonstrate a comparable sensitivity of detecting the translational targeting errors, while the cylindrical diode array is more sensitive to the rotational targeting error. The MC method is necessary for dose calculations in the cylindrical diode array phantom because the ray-tracing algorithm fails to handle the high-Z diodes and the acrylic phantom. For all the patient plans, the cylindrical diode array/ planar ion chamber array demonstrate 100%/>;92%(3%/3 mm) passing rates. The feasibility of using both systems for robotic radiosurgery system patient-specific QA

  19. High Power Laser Diode Arrays for 2-Micron Solid State Coherent Lidars Applications

    NASA Technical Reports Server (NTRS)

    Amzajerdian, Farzin; Meadows, Byron; Kavaya, Michael J.; Singh, Upendra; Sudesh, Vikas; Baker, Nathaniel

    2003-01-01

    Laser diode arrays are critical components of any diode-pumped solid state laser systems, constraining their performance and reliability. Laser diode arrays (LDAs) are used as the pump source for energizing the solid state lasing media to generate an intense coherent laser beam with a high spatial and spectral quality. The solid state laser design and the characteristics of its lasing materials define the operating wavelength, pulse duration, and power of the laser diodes. The pump requirements for high pulse energy 2-micron solid state lasers are substantially different from those of more widely used 1-micron lasers and in many aspects more challenging [1]. Furthermore, the reliability and lifetime demanded by many coherent lidar applications, such as global wind profiling from space and long-range clear air turbulence detection from aircraft, are beyond the capability of currently available LDAs. In addition to the need for more reliable LDAs with longer lifetime, further improvement in the operational parameters of high power quasi-cw LDAs, such as electrical efficiency, brightness, and duty cycle, are also necessary for developing cost-effective 2-micron coherent lidar systems for applications that impose stringent size, heat dissipation, and power constraints. Global wind sounding from space is one of such applications, which is the main driver for this work as part of NASA s Laser Risk Reduction Program. This paper discusses the current state of the 792 nm LDA technology and the technology areas being pursued toward improving their performance. The design and development of a unique characterization facility for addressing the specific issues associated with the LDAs for pumping 2-micron coherent lidar transmitters and identifying areas of technological improvement will be described. Finally, the results of measurements to date on various standard laser diode packages, as well as custom-designed packages with potentially longer lifetime, will be reported.

  20. Dosimetric Characteristics of a Two-Dimensional Diode Array Detector Irradiated with Passively Scattered Proton Beams

    PubMed Central

    Liengsawangwong, Praimakorn; Sahoo, Nanayan; Ding, Xiaoning; Lii, MingFwu; Gillin, Michale T.; Zhu, Xiaorong Ronald

    2015-01-01

    Purpose: To evaluate the dosimetric characteristics of a two-dimensional (2D) diode array detector irradiated with passively scattered proton beams. Materials and Methods: A diode array detector, MapCHECK (Model 1175, Sun Nuclear, Melbourne, FL, USA) was characterized in passive-scattered proton beams. The relative sensitivity of the diodes and absolute dose calibration were determined using a 250 MeV beam. The pristine Bragg curves (PBCs) measured by MapCHECK diodes were compared with those of an ion chamber using a range shift method. The water-equivalent thickness (WET) of the diode array detector’s intrinsic buildup also was determined. The inverse square dependence, linearity, and other proton dosimetric quantities measured by MapCHECK were also compared with those of the ion chambers. The change in the absolute dose response of the MapCHECK as a function of accumulated radiation dose was used as an indicator of radiation damage to the diodes. 2D dose distribution with and without the compensator were measured and compared with the treatment planning system (TPS) calculations. Results: The WET of the MapCHECK diode’s buildup was determined to be 1.7 cm. The MapCHECK-measured PBC were virtually identical to those measured by a parallel-plate ion chamber for 160, 180, and 250 MeV proton beams. The inverse square results of the MapCHECK were within ±0.4% of the ion chamber results. The linearity of MapCHECK results was within 1% of those from the ion chamber as measured in the range between 10 and 300 MU. All other dosimetric quantities were within 1.3% of the ion chamber results. The 2D dose distributions for non-clinical fields without compensator and the patient treatment fields with the compensator were consistent with the TPS results. The absolute dose response of the MapCHECK was changed by 7.4% after an accumulated dose increased by 170 Gy. Conclusions: The MapCHECK is a convenient and useful tool for 2D dose distribution measurements using passively

  1. Omnidirectional multiview three-dimensional display based on direction-selective light-emitting diode array

    NASA Astrophysics Data System (ADS)

    Yan, Caijie; Liu, Xu; Liu, Di; Xie, Jing; Xia, Xin Xing; Li, Haifeng

    2011-03-01

    A volumetric display system based on a rotating light-emitting diode (LED) array panel can realize a three-dimensional (3-D) display truthfully in the space, but the drawback is missing the occlusion of a 3-D image. We propose an omnidirectional 3-D display with correct occlusion based on a direction-selective LED array panel, which is realized by setting a direction-convergent diaphragm array in front of the LED array. Every diaphragm restricts a light-emitting characteristic of every LED. By using direction-convergent diaphragm array, the observer around the display system can only see one image displayed by the LED array at the corresponding position. With the high-speed rotation of the LED panel, a series of views of a 3-D scene are displayed every angle patch in one circle. We set up an acquisition system to record 180 views of the 3-D scene with a rotating camera along a circle, and then the 180 images are displayed sequentially on the rotating direction-selective LED array to get a 360 deg 3-D display. This 3-D display technology has two main advantages: easy to get viewer-position-dependent correct occlusion and simplify the 3-D data preprocessing process which is helpful to real-time 3-D display.

  2. 4H-SiC Schottky diode arrays for X-ray detection

    NASA Astrophysics Data System (ADS)

    Lioliou, G.; Chan, H. K.; Gohil, T.; Vassilevski, K. V.; Wright, N. G.; Horsfall, A. B.; Barnett, A. M.

    2016-12-01

    Five SiC Schottky photodiodes for X-ray detection have been electrically characterized at room temperature. One representative diode was also electrically characterized over the temperature range 20°C to 140 °C. The performance at 30 °C of all five X-ray detectors, in both current mode and for photon counting X-ray spectroscopy was investigated. The diodes were fabricated in an array form such that they could be operated as either a 2×2 or 1×3 pixel array. Although the devices showed double barrier heights, high ideality factors and higher than expected leakage current at room temperature (12 nA/cm2 at an internal electric field of 105 kV/cm), they operated as spectroscopic photon counting soft X-ray detectors uncooled at 30 °C. The measured energy resolution (FWHM at 17.4 keV, Mo Kα) varied from 1.36 to 1.68 keV among different diodes.

  3. Improved heat sinking for laser-diode arrays using microchannels in CVD diamond

    SciTech Connect

    Goodson, K.E.; Kurabayashi, K.; Pease, R.F.W.

    1995-12-31

    This work proposes a novel cooling system for high-power laser-diode arrays, for which the maximum optical output power density per unit surface area is limited by the temperature rise due to self heating. The proposed system uses a microchannel heat sink made of chemical-vapor-deposited (CVD) diamond, whose high thermal conductivity increases the efficiency of the channel wall-fins and reduces the array-to-coolant thermal resistance. The thermal resistance is further reduced in the proposed system by minimizing the separation between active regions and the diamond using epitaxial lift-off (ELO) and grafting technology. This work predicts the array-to-coolant thermal resistance using a simple model for the combined conduction and convection problem. The resistance is calculated to be 75% less than that for a conventional configuration using a silicon microchannel heat sink. The present analysis strongly motivates a future experimental study.

  4. A digital optical phase-locked loop for diode lasers based on field programmable gate array.

    PubMed

    Xu, Zhouxiang; Zhang, Xian; Huang, Kaikai; Lu, Xuanhui

    2012-09-01

    We have designed and implemented a highly digital optical phase-locked loop (OPLL) for diode lasers in atom interferometry. The three parts of controlling circuit in this OPLL, including phase and frequency detector (PFD), loop filter and proportional integral derivative (PID) controller, are implemented in a single field programmable gate array chip. A structure type compatible with the model MAX9382∕MCH12140 is chosen for PFD and pipeline and parallelism technology have been adapted in PID controller. Especially, high speed clock and twisted ring counter have been integrated in the most crucial part, the loop filter. This OPLL has the narrow beat note line width below 1 Hz, residual mean-square phase error of 0.14 rad(2) and transition time of 100 μs under 10 MHz frequency step. A main innovation of this design is the completely digitalization of the whole controlling circuit in OPLL for diode lasers.

  5. A digital optical phase-locked loop for diode lasers based on field programmable gate array

    NASA Astrophysics Data System (ADS)

    Xu, Zhouxiang; Zhang, Xian; Huang, Kaikai; Lu, Xuanhui

    2012-09-01

    We have designed and implemented a highly digital optical phase-locked loop (OPLL) for diode lasers in atom interferometry. The three parts of controlling circuit in this OPLL, including phase and frequency detector (PFD), loop filter and proportional integral derivative (PID) controller, are implemented in a single field programmable gate array chip. A structure type compatible with the model MAX9382/MCH12140 is chosen for PFD and pipeline and parallelism technology have been adapted in PID controller. Especially, high speed clock and twisted ring counter have been integrated in the most crucial part, the loop filter. This OPLL has the narrow beat note line width below 1 Hz, residual mean-square phase error of 0.14 rad2 and transition time of 100 μs under 10 MHz frequency step. A main innovation of this design is the completely digitalization of the whole controlling circuit in OPLL for diode lasers.

  6. Bypass Diode Temperature Tests of a Solar Array Coupon Under Space Thermal Environment Conditions

    NASA Technical Reports Server (NTRS)

    Wright, Kenneth H., Jr.; Schneider, Todd A.; Vaughn, Jason A.; Hoang, Bao; Wong, Frankie; Wu, Gordon

    2016-01-01

    Tests were performed on a 56-cell Advanced Triple Junction solar array coupon whose purpose was to determine margin available for bypass diodes integrated with new, large multi-junction solar cells that are manufactured from a 4-inch wafer. The tests were performed under high vacuum with coupon back side thermal conditions of both cold and ambient. The bypass diodes were subjected to a sequence of increasing discrete current steps from 0 Amp to 2.0 Amp in steps of 0.25 Amp. At each current step, a temperature measurement was obtained via remote viewing by an infrared camera. This paper discusses the experimental methodology, experiment results, and the thermal model.

  7. By-Pass Diode Temperature Tests of a Solar Array Coupon Under Space Thermal Environment Conditions

    NASA Technical Reports Server (NTRS)

    Wright, Kenneth H., Jr.; Schneider, Todd A.; Vaughn, Jason A.; Hoang, Bao; Wong, Frankie

    2016-01-01

    Tests were performed on a 56-cell Advanced Triple Junction solar array coupon whose purpose was to determine margin available for bypass diodes integrated with new, large multi-junction solar cells that are manufactured from a 4-inch wafer. The tests were performed under high vacuum with cold and ambient coupon back-side. The bypass diodes were subjected to a sequence of increasing discrete current steps from 0 Amp to 2.0 Amp in steps of 0.25 Amp. At each current step, a temperature measurement was obtained via remote viewing by an infrared camera. This paper discusses the experimental methodology, including the calibration of the thermal imaging system, and the results.

  8. A digital optical phase-locked loop for diode lasers based on field programmable gate array

    SciTech Connect

    Xu Zhouxiang; Zhang Xian; Huang Kaikai; Lu Xuanhui

    2012-09-15

    We have designed and implemented a highly digital optical phase-locked loop (OPLL) for diode lasers in atom interferometry. The three parts of controlling circuit in this OPLL, including phase and frequency detector (PFD), loop filter and proportional integral derivative (PID) controller, are implemented in a single field programmable gate array chip. A structure type compatible with the model MAX9382/MCH12140 is chosen for PFD and pipeline and parallelism technology have been adapted in PID controller. Especially, high speed clock and twisted ring counter have been integrated in the most crucial part, the loop filter. This OPLL has the narrow beat note line width below 1 Hz, residual mean-square phase error of 0.14 rad{sup 2} and transition time of 100 {mu}s under 10 MHz frequency step. A main innovation of this design is the completely digitalization of the whole controlling circuit in OPLL for diode lasers.

  9. A photon-counting photodiode array detector for far ultraviolet (FUV) astronomy

    NASA Technical Reports Server (NTRS)

    Hartig, G. F.; Moos, H. W.; Pembroke, R.; Bowers, C.

    1982-01-01

    A compact, stable, single-stage intensified photodiode array detector designed for photon-counting, far ultraviolet astronomy applications employs a saturable, 'C'-type MCP (Galileo S. MCP 25-25) to produce high gain pulses with a narrowly peaked pulse height distribution. The P-20 output phosphor exhibits a very short decay time, due to the high current density of the electron pulses. This intensifier is being coupled to a self-scanning linear photodiode array which has a fiber optic input window which allows direct, rigid mechanical coupling with minimal light loss. The array was scanned at a 250 KHz pixel rate. The detector exhibits more than adequate signal-to-noise ratio for pulse counting and event location.

  10. Multi-spectral solar telescope array IV; The soft x-ray and extreme ultraviolet filters

    SciTech Connect

    Lindblom, J.F.; O'Neal, R.H.; Walker, A.B.C. Jr. ); Powell, F.R. ); Barbee, T.W. Jr. ); Hoover, R.B. ); Powell, S.F. )

    1991-08-01

    The multilayer mirrors used in the normal-incidence optical systems of the Multi-Spectral Solar Telescope Array (MSSTA) are efficient reflectors for soft x-ray/extreme ultraviolet (EUV) radiation at wavelengths that satisfy the Bragg condition, thus allowing a narrow band of the soft x-ray/EUV spectrum to be isolated. However, these same mirrors are also excellent reflectors in the visible, ultraviolet, and far-ultraviolet (FUV) part of the spectrum, where normal incidence reflectivities can exceed 50%. Furthermore, the sun emits far more radiation in the ultraviolet and visible part of the spectrum than it does in the soft x-ray/EUV. For this reason, thin foil filters are employed to eliminate the unwanted longer wavelength solar emission. The MSSTA instrument uses various combinations of thin foil filters composed of aluminum carbon, tellurium, potassium bromide, beryllium, molybdenum, rhodium, and phthalocyanine to achieve the desired radiation rejection characteristics. In this paper, the authors discuss issues concerning the design, manufacture, and predicted performance of MSSTA filters.

  11. An AlGaN Core-Shell Tunnel Junction Nanowire Light-Emitting Diode Operating in the Ultraviolet-C Band.

    PubMed

    Sadaf, S M; Zhao, S; Wu, Y; Ra, Y-H; Liu, X; Vanka, S; Mi, Z

    2017-02-08

    To date, semiconductor light emitting diodes (LEDs) operating in the deep ultraviolet (UV) spectral range exhibit very low efficiency due to the presence of large densities of defects and extremely inefficient p-type conduction of conventional AlGaN quantum well heterostructures. We have demonstrated that such critical issues can be potentially addressed by using nearly defect-free AlGaN tunnel junction core-shell nanowire heterostructures. The core-shell nanowire arrays exhibit high photoluminescence efficiency (∼80%) in the UV-C band at room temperature. With the incorporation of an epitaxial Al tunnel junction, the p-(Al)GaN contact-free nanowire deep UV LEDs showed nearly one order of magnitude reduction in the device resistance, compared to the conventional nanowire p-i-n device. The unpackaged Al tunnel junction deep UV LEDs exhibit an output power >8 mW and a peak external quantum efficiency ∼0.4%, which are nearly one to two orders of magnitude higher than previously reported AlGaN nanowire devices. Detailed studies further suggest that the maximum achievable efficiency is limited by electron overflow and poor light extraction efficiency due to the TM polarized emission.

  12. Design of micro, flexible light-emitting diode arrays and fabrication of flexible electrodes

    NASA Astrophysics Data System (ADS)

    Gao, Dan; Wang, Weibiao; Liang, Zhongzhu; Liang, Jingqiu; Qin, Yuxin; Lv, Jinguang

    2016-10-01

    In this study, we design micro, flexible light-emitting diode (LED) array devices. Using theoretical calculations and finite element simulations, we analyze the deformation of the conventional single electrode bar. Through structure optimization, we obtain a three-dimensional (3D), chain-shaped electrode structure, which has a greater bending degree. The optimized electrodes not only have a bigger bend but can also be made to spin. When the supporting body is made of polydimethylsiloxane (PDMS), the maximum bending degree of the micro, flexible LED arrays (4  ×  1 arrays) was approximately 230 µm this was obtained using the finite element method. The device (4  ×  1 arrays) can stretch to 15%. This paper describes the fabrication of micro, flexible LED arrays using microelectromechancial (MEMS) technology combined with electroplating technology. Specifically, the isolated grooves are made by dry etching which can isolate and protect the light-emitting units. A combination of MEMS technology and wet etching is used to fabricate the large size spacing.

  13. New red phosphor for near-ultraviolet light-emitting diodes with high color-purity

    SciTech Connect

    Wang, Zhengliang; He, Pei; Wang, Rui; Zhao, Jishou; Gong, Menglian

    2010-02-15

    New red phosphors, Na{sub 5}Eu(MoO{sub 4}){sub 4} doped with boron oxide were prepared by the solid-state reaction. Their structure and photo-luminescent properties were investigated. With the introduction of boron oxide, the red emission intensity of the phosphors under 395 nm excitation is strengthened, with high color-purity (x = 0.673, y = 0.327). The single red light-emitting diode was obtained by combining InGaN chip with the red phosphor, bright red light can be observed by naked eyes from the red light-emitting diodes under a forward bias of 20 mA.

  14. Current-voltage characteristics of Au/PLiMMA/n-Si diode under ultraviolet irradiation

    NASA Astrophysics Data System (ADS)

    Çulcu, Hayat; Gökçen, Muharrem; Allı, Abdulkadir; Allı, Sema

    2017-04-01

    Au/poly (linoleic acid)-g-poly(methyl methacrylate)(PLiMMA)/n-Si diode was fabricated and current-voltage (I-V) characteristics of this diode were measured in dark and under 365 nm ultra violet (UV) irradiation at room temperature. Main electrical parameters; such as leakage current (Io), ideality factor (n), zero-bias barrier height (ΦBo) and surface states density (Nss) were calculated using thermionic emission theory to obtain UV irradiation intensity dependence of these parameters. Also alternatively n, barrier height (ΦB) and series resistance (Rs) was calculated by Cheung&Cheung method. These alternatively obtained values were given and compared with the literature.

  15. Enhancing the light extraction efficiency of AlGaN deep ultraviolet light emitting diodes by using nanowire structures

    SciTech Connect

    Djavid, Mehrdad; Mi, Zetian

    2016-02-01

    The performance of conventional AlGaN deep ultraviolet light emitting diodes has been limited by the extremely low light extraction efficiency (<10%), due to the unique transverse magnetic (TM) polarized light emission. Here, we show that, by exploiting the lateral side emission, the extraction efficiency of TM polarized light can be significantly enhanced in AlGaN nanowire structures. Using the three-dimensional finite-difference time domain simulation, we demonstrate that the nanowire structures can be designed to inhibit the emission of guided modes and redirect trapped light into radiated modes. A light extraction efficiency of more than 70% can, in principle, be achieved by carefully optimizing the nanowire size, nanowire spacing, and p-GaN thickness.

  16. Advantages of AlGaN-based deep ultraviolet light-emitting diodes with a superlattice electron blocking layer

    NASA Astrophysics Data System (ADS)

    Sun, Pai; Bao, Xianglong; Liu, Songqing; Ye, Chunya; Yuan, Zhaorong; Wu, Yukun; Li, Shuping; Kang, Junyong

    2015-09-01

    The properties of 298 nm AlGaN based deep ultraviolet light-emitting diodes (UV LEDs) with different Al mole compositions in the conventional electron blocking layer (EBL) are discussed in this paper, the optimal Al mole composition of the conventional EBL is identified at 0.8. The improved structure with an AlGaN/AlGaN superlattice (SL) electron blocking layer (EBL) was then investigated numerically. The electrical and optical properties, band diagrams, carrier concentrations, radiative recombination rates and internal quantum efficiency (IQE) were investigated by APSYS software, and results show that the deep UV LED with superlattice EBL performed much better than the conventional EBL deep UV LED, attributed to reduced electrons leakage and increased holes injection.

  17. High efficiency single Ag nanowire/p-GaN substrate Schottky junction-based ultraviolet light emitting diodes

    SciTech Connect

    Wu, Y.; Li, X.; Xu, P.; Wang, Y.; Shen, X.; Liu, X.; Yang, Q.; Hasan, T.

    2015-02-02

    We report a high efficiency single Ag nanowire (NW)/p-GaN substrate Schottky junction-based ultraviolet light emitting diode (UV-LED). The device demonstrates deep UV free exciton electroluminescence at 362.5 nm. The dominant emission, detectable at ultralow (<1 μA) forward current, does not exhibit any shifts when the forward current is increased. External quantum efficiency (EQE) as high as 0.9% is achieved at 25 μA current at room temperature. Experiments and simulation analysis show that devices fabricated with thinner Ag NWs have higher EQE. However, for very thin Ag NWs (diameter < 250 nm), this trend breaks down due to heat accumulation in the NWs. Our simple device architecture offers a potentially cost-effective scheme to fabricate high efficiency Schottky junction-based UV-LEDs.

  18. Molecular beam epitaxial growth and characterization of Al(Ga)N nanowire deep ultraviolet light emitting diodes and lasers

    NASA Astrophysics Data System (ADS)

    Mi, Z.; Zhao, S.; Woo, S. Y.; Bugnet, M.; Djavid, M.; Liu, X.; Kang, J.; Kong, X.; Ji, W.; Guo, H.; Liu, Z.; Botton, G. A.

    2016-09-01

    We report on the detailed molecular beam epitaxial growth and characterization of Al(Ga)N nanowire heterostructures on Si and their applications for deep ultraviolet light emitting diodes and lasers. The nanowires are formed under nitrogen-rich conditions without using any metal catalyst. Compared to conventional epilayers, Mg-dopant incorporation is significantly enhanced in nearly strain- and defect-free Al(Ga)N nanowire structures, leading to efficient p-type conduction. The resulting Al(Ga)N nanowire LEDs exhibit excellent performance, including a turn-on voltage of ∼5.5 V for an AlN nanowire LED operating at 207 nm. The design, fabrication, and performance of an electrically injected AlGaN nanowire laser operating in the UV-B band is also presented.

  19. High-output-power 255/280/310 nm deep ultraviolet light-emitting diodes and their lifetime characteristics

    NASA Astrophysics Data System (ADS)

    Fujioka, A.; Asada, K.; Yamada, H.; Ohtsuka, T.; Ogawa, T.; Kosugi, T.; Kishikawa, D.; Mukai, T.

    2014-06-01

    255/280/310 nm deep ultraviolet light-emitting diodes (DUV LEDs) suitable for high-current operation are reported. Newly developed 1 mm sized chips are installed in a commercial package with a two-series configuration. At a forward current of 350 mA, we measured powers of 45.2, 93.3, and 65.8 mW for the 255, 280, and 310 nm LEDs, respectively. The corresponding external quantum efficiencies per serial circuit were 1.3, 3.0, and 2.4%, and successful chip scalability was demonstrated. The 50% lifetime of the 280 nm LED die was estimated to be 3000 h at a junction temperature of 30 °C.

  20. Remarkable improvement in electroluminescence benefited from appropriate electron injection and transporting in ultraviolet organic light-emitting diode

    NASA Astrophysics Data System (ADS)

    You, Fengjiao; Mo, Bingjie; Liu, Liming; Wang, Honghang; Bin Wei; Xu, Jiwen; Zhang, Xiaowen

    2016-08-01

    Suitable thickness of LiF and 4,7-diphenyl-1, 10-phenanthroline with slightly weakened electron injection and transporting is proposed to match the intractable hole injection capacity in ultraviolet organic light-emitting diode (UV OLED). By using this strategy, the device performance is remarkably improved. With 4,4‧-bis(carbazol-9-yl)biphenyl (CBP) and 3-(4-biphenyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole (TAZ) as emitters, the UV OLED shows maximum radiance of 5.8 mW/cm2 and external quantum efficiency of 2.1% with emission peak of ~380 nm predominantly from TAZ and noticeable shoulder emission of ~410 nm from CBP. The retarded electron injection and transporting contribute to optimizing hole-electron recombination zone and balance within the emitting layers, which accounts for the improved electroluminescent intensity. The detailed mechanism is further clarified with impedance spectroscopy.

  1. A fiber optic, ultraviolet light-emitting diode-based, two wavelength fluorometer for monitoring reactive adsorption

    NASA Astrophysics Data System (ADS)

    Granz, Christopher D.; Schindler, Bryan J.; Peterson, Gregory W.; Whitten, James E.

    2016-03-01

    Construction and use of an ultraviolet light-emitting diode-based fluorometer for measuring photoluminescence (PL) from powder samples with a fiber optic probe is described. Fluorescence at two wavelengths is detected by miniature photomultiplier tubes, each equipped with a different band pass filter, whose outputs are analyzed by a microprocessor. Photoluminescent metal oxides and hydroxides, and other semiconducting nanoparticles, often undergo changes in their emission spectra upon exposure to reactive gases, and the ratio of the PL intensities at two wavelengths is diagnostic of adsorption. Use of this instrument for reactive gas sensing and gas filtration applications is illustrated by measuring changes in the PL ratio for zirconium hydroxide and zinc oxide particles upon exposure to air containing low concentrations of sulfur dioxide.

  2. Optical and Thermal Analyses of High-Power Laser Diode Arrays

    NASA Technical Reports Server (NTRS)

    Vasilyev, Aleksey; Allan, Graham R.; Schafer, John; Stephen, Mark A.; Young, Stefano

    2004-01-01

    An important need, especially for space-borne applications, is the early identification and rejection of laser diode arrays which may fail prematurely. The search for reliable failure predictors is ongoing and has led to the development of two techniques, infrared imagery and monitoring the Temporally-resolved and Spectrally-Resolved (TSR) optical output from which temperature of the device can be measured. This is in addition to power monitoring on long term burn stations. A direct measurement of the temperature of the active region is an important parameter as the lifetime of Laser Diode Arrays (LDA) decreases exponentially with increasing temperature. We measure the temperature from time-resolving the spectral emission in an analogous method to Voss et al. In this paper we briefly discuss the measurement setup and present temperature data derived from thermal images and TSR data for two differently designed high-power 808 nanometer LDA packages of similar specification operated in an electrical and thermal environment that mimic the expected operational conditions.

  3. Detection and modeling of leakage current in AlGaN-based deep ultraviolet light-emitting diodes

    DOE PAGES

    Moseley, Michael William; Allerman, Andrew A.; Crawford, Mary H.; ...

    2015-03-01

    Current-voltage (IV) characteristics of two AlGaN-based deep ultraviolet (DUV) light-emitting diodes (LEDs) with differing densities of open-core threading dislocations (nanopipes) are analyzed. A three-diode circuit is simulated to emulate the IV characteristics of the DUV-LEDs, but is only able to accurately model the lower leakage current, lower nanopipe density DUV-LED. It was found that current leakage through the nanopipes in these structures is rectifying, despite nanopipes being previously established as inherently n-type. Using defect-sensitive etching, the nanopipes are revealed to terminate within the p-type GaN capping layer of the DUV-LEDs. The circuit model is modified to account for another p-nmore » junction between the n-type nanopipes and the p-type GaN, and an excellent fit to the IV characteristics of the leaky DUV-LED is achieved.« less

  4. Characterization of electrically-active defects in ultraviolet light-emitting diodes with laser-based failure analysis techniques

    SciTech Connect

    Miller, Mary A.; Tangyunyong, Paiboon; Cole, Edward I.

    2016-01-14

    Laser-based failure analysis techniques demonstrate the ability to quickly and non-intrusively screen deep ultraviolet light-emitting diodes (LEDs) for electrically-active defects. In particular, two laser-based techniques, light-induced voltage alteration and thermally-induced voltage alteration, generate applied voltage maps (AVMs) that provide information on electrically-active defect behavior including turn-on bias, density, and spatial location. Here, multiple commercial LEDs were examined and found to have dark defect signals in the AVM indicating a site of reduced resistance or leakage through the diode. The existence of the dark defect signals in the AVM correlates strongly with an increased forward-bias leakage current. This increased leakage is not present in devices without AVM signals. Transmission electron microscopy analysis of a dark defect signal site revealed a dislocation cluster through the pn junction. The cluster included an open core dislocation. Even though LEDs with few dark AVM defect signals did not correlate strongly with power loss, direct association between increased open core dislocation densities and reduced LED device performance has been presented elsewhere [M. W. Moseley et al., J. Appl. Phys. 117, 095301 (2015)].

  5. Characterization of electrically-active defects in ultraviolet light-emitting diodes with laser-based failure analysis techniques

    SciTech Connect

    Miller, Mary A.; Tangyunyong, Paiboon; Edward I. Cole, Jr.

    2016-01-12

    In this study, laser-based failure analysis techniques demonstrate the ability to quickly and non-intrusively screen deep ultraviolet light-emitting diodes(LEDs) for electrically-active defects. In particular, two laser-based techniques, light-induced voltage alteration and thermally-induced voltage alteration, generate applied voltage maps (AVMs) that provide information on electrically-active defect behavior including turn-on bias, density, and spatial location. Here, multiple commercial LEDs were examined and found to have dark defect signals in the AVM indicating a site of reduced resistance or leakage through the diode. The existence of the dark defect signals in the AVM correlates strongly with an increased forward-bias leakage current. This increased leakage is not present in devices without AVM signals. Transmission electron microscopyanalysis of a dark defect signal site revealed a dislocation cluster through the pn junction. The cluster included an open core dislocation. Even though LEDs with few dark AVM defect signals did not correlate strongly with power loss, direct association between increased open core dislocation densities and reduced LED device performance has been presented elsewhere [M. W. Moseley et al., J. Appl. Phys. 117, 095301 (2015)].

  6. Characterization of electrically-active defects in ultraviolet light-emitting diodes with laser-based failure analysis techniques

    DOE PAGES

    Miller, Mary A.; Tangyunyong, Paiboon; Edward I. Cole, Jr.

    2016-01-12

    In this study, laser-based failure analysis techniques demonstrate the ability to quickly and non-intrusively screen deep ultraviolet light-emitting diodes(LEDs) for electrically-active defects. In particular, two laser-based techniques, light-induced voltage alteration and thermally-induced voltage alteration, generate applied voltage maps (AVMs) that provide information on electrically-active defect behavior including turn-on bias, density, and spatial location. Here, multiple commercial LEDs were examined and found to have dark defect signals in the AVM indicating a site of reduced resistance or leakage through the diode. The existence of the dark defect signals in the AVM correlates strongly with an increased forward-bias leakage current. This increasedmore » leakage is not present in devices without AVM signals. Transmission electron microscopyanalysis of a dark defect signal site revealed a dislocation cluster through the pn junction. The cluster included an open core dislocation. Even though LEDs with few dark AVM defect signals did not correlate strongly with power loss, direct association between increased open core dislocation densities and reduced LED device performance has been presented elsewhere [M. W. Moseley et al., J. Appl. Phys. 117, 095301 (2015)].« less

  7. Characterization of electrically-active defects in ultraviolet light-emitting diodes with laser-based failure analysis techniques

    NASA Astrophysics Data System (ADS)

    Miller, Mary A.; Tangyunyong, Paiboon; Cole, Edward I.

    2016-01-01

    Laser-based failure analysis techniques demonstrate the ability to quickly and non-intrusively screen deep ultraviolet light-emitting diodes (LEDs) for electrically-active defects. In particular, two laser-based techniques, light-induced voltage alteration and thermally-induced voltage alteration, generate applied voltage maps (AVMs) that provide information on electrically-active defect behavior including turn-on bias, density, and spatial location. Here, multiple commercial LEDs were examined and found to have dark defect signals in the AVM indicating a site of reduced resistance or leakage through the diode. The existence of the dark defect signals in the AVM correlates strongly with an increased forward-bias leakage current. This increased leakage is not present in devices without AVM signals. Transmission electron microscopy analysis of a dark defect signal site revealed a dislocation cluster through the pn junction. The cluster included an open core dislocation. Even though LEDs with few dark AVM defect signals did not correlate strongly with power loss, direct association between increased open core dislocation densities and reduced LED device performance has been presented elsewhere [M. W. Moseley et al., J. Appl. Phys. 117, 095301 (2015)].

  8. Multiple detector focal plane array ultraviolet spectrometer for the AMPS laboratory

    NASA Technical Reports Server (NTRS)

    Feldman, P. D.

    1975-01-01

    The possibility of meeting the requirements of the amps spectroscopic instrumentation by using a multi-element focal plane detector array in a conventional spectrograph mount was examined. The requirements of the detector array were determined from the optical design of the spectrometer which in turn depends on the desired level of resolution and sensitivity required. The choice of available detectors and their associated electronics and controls was surveyed, bearing in mind that the data collection rate from this system is so great that on-board processing and reduction of data are absolutely essential. Finally, parallel developments in instrumentation for imaging in astronomy were examined, both in the ultraviolet (for the Large Space Telescope as well as other rocket and satellite programs) and in the visible, to determine what progress in that area can have direct bearing on atmospheric spectroscopy.

  9. Spatially resolved bolometric measurement and electron temperature measurement using diode arrays

    SciTech Connect

    Koguchi, H.; Shimada, T.; Asai, T.; Yagi, Y.; Hirano, Y.; Sakakita, H.

    2004-10-01

    In this article, the measurement system for the total radiation and electron temperature profiles to be installed in a reversed-field pinch machine, toroidal pinch experiment, RX [TPE-RX, R/a=1.72/0.45 m, Ipdiode arrays. Each array can measure radiation along 20 lines of sight and the radial profile of the radiation. One set of the arrays is used for the bolometric measurement in the range from visible light to soft x-ray. Two sets of the arrays are used for the soft-x ray and electron temperature measurements employing a double-filter method. We will use this system to investigate the plasma-wall interaction, radiation loss, and confinement properties in the core plasma region. We will extend the use of this system for tomographic analysis of electron temperature, a concept of which is also presented.

  10. Modeling Ultraviolet (UV) Light Emitting Diode (LED) Energy Propagation in Reactor Vessels

    DTIC Science & Technology

    2014-03-27

    urban wastewater effluent than a single wavelength used alone (Chevremont, Farnet, Coulomb, & Boudenne, 2012; Oguma, Kita, Sakai, Murakami...into waste streams. Certain chemicals may be detrimental to the effectiveness of municipal wastewater treatment plants. This can lead to reduced...introduced to wastewater treatment plants. One of these methods includes an Advanced Oxidation Process (AOP) which uses ultraviolet (UV) energy and

  11. A microfabricated sun sensor using GaN-on-sapphire ultraviolet photodetector arrays

    NASA Astrophysics Data System (ADS)

    Miller, Ruth A.; So, Hongyun; Chiamori, Heather C.; Suria, Ateeq J.; Chapin, Caitlin A.; Senesky, Debbie G.

    2016-09-01

    A miniature sensor for detecting the orientation of incident ultraviolet light was microfabricated using gallium nitride (GaN)-on-sapphire substrates and semi-transparent interdigitated gold electrodes for sun sensing applications. The individual metal-semiconductor-metal photodetector elements were shown to have a stable and repeatable response with a high sensitivity (photocurrent-to-dark current ratio (PDCR) = 2.4 at -1 V bias) and a high responsivity (3200 A/W at -1 V bias) under ultraviolet (365 nm) illumination. The 3 × 3 GaN-on-sapphire ultraviolet photodetector array was integrated with a gold aperture to realize a miniature sun sensor (1.35 mm × 1.35 mm) capable of determining incident light angles with a ±45° field of view. Using a simple comparative figure of merit algorithm, measurement of incident light angles of 0° and 45° was quantitatively and qualitatively (visually) demonstrated by the sun sensor, supporting the use of GaN-based sun sensors for orientation, navigation, and tracking of the sun within the harsh environment of space.

  12. Tunable absorption resonances in the ultraviolet for InP nanowire arrays.

    PubMed

    Aghaeipour, Mahtab; Anttu, Nicklas; Nylund, Gustav; Samuelson, Lars; Lehmann, Sebastian; Pistol, Mats-Erik

    2014-11-17

    The ability to tune the photon absorptance spectrum is an attracting way of tailoring the response of devices like photodetectors and solar cells. Here, we measure the reflectance spectra of InP substrates patterned with arrays of vertically standing InP nanowires. Using the reflectance spectra, we calculate and analyze the corresponding absorptance spectra of the nanowires. We show that we can tune absorption resonances for the nanowire arrays into the ultraviolet by decreasing the diameter of the nanowires. When we compare our measurements with electromagnetic modeling, we generally find good agreement. Interestingly, the remaining differences between modeled and measured spectra are attributed to a crystal-phase dependence in the refractive index of InP. Specifically, we find indication of significant differences in the refractive index between the modeled zinc-blende InP nanowires and the measured wurtzite InP nanowires in the ultraviolet. We believe that such crystal-phase dependent differences in the refractive index affect the possibility to excite optical resonances in the large wavelength range of 345 < λ < 390 nm. To support this claim, we investigated how resonances in nanostructures can be shifted in wavelength by geometrical tuning. We find that dispersion in the refractive index can dominate over geometrical tuning and stop the possibility for such shifting. Our results open the door for using crystal-phase engineering to optimize the absorption in InP nanowire-based solar cells and photodetectors.

  13. Feasibility study of using a Zener diode as the selection device for bipolar RRAM and WORM memory arrays

    NASA Astrophysics Data System (ADS)

    Li, Yingtao; Fu, Liping; Tao, Chunlan; Jiang, Xinyu; Sun, Pengxiao

    2014-01-01

    Cross-bar arrays are usually used for the high density application of resistive random access memory (RRAM) devices. However, cross-talk interference limits an increase in the integration density. In this paper, the Zener diode is proposed as a selection device to suppress the sneak current in bipolar RRAM arrays. Measurement results show that the Zener diode can act as a good selection device, and the sneak current can be effectively suppressed. The readout margin is sufficiently improved compared to that obtained without the selection device. Due to the improvement for the reading disturbance, the size of the cross-bar array can be enhanced to more than 103 × 103. Furthermore, the possibility of using a write-once-read-many-times (WORM) cross-bar array is also demonstrated by connecting the Zener diode and the bipolar RRAM in series. These results strongly suggest that using a Zener diode as a selection device opens up great opportunities to realize high density bipolar RRAM arrays.

  14. Time resolved metal line profile by near-ultraviolet tunable diode laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Vitelaru, C.; de Poucques, L.; Minea, T. M.; Popa, G.

    2011-03-01

    Pulsed systems are extensively used to produce active species such as atoms, radicals, excited states, etc. The tunable diode laser absorption spectroscopy (TD-LAS) is successfully used to quantify the density of absorbing species, but especially for stationary or slow changing systems. The time resolved-direct absorption profile (TR-DAP) measurement method by TD-LAS, with time resolution of μs is proposed here as an extension of the regular use of diode laser absorption spectroscopy. The spectral narrowness of laser diodes, especially in the blue range (˜0.01 pm), combined with the nanosecond fast trigger of the magnetron pulsed plasma and long trace recording on the oscilloscope (period of second scale) permit the detection of the sputtered titanium metal evolution in the afterglow (˜ms). TR-DAP method can follow the time-dependence of the temperature (Doppler profile) and the density (deduced from the absorbance) of any medium and heavy species in a pulsed system.

  15. Fabrication of an optical lens array using ultraviolet light and ultrasonication.

    PubMed

    Taniguchi, Satoki; Koyama, Daisuke; Nakamura, Kentaro; Matsukawa, Mami

    2015-04-01

    A technique to form an optical lens array using an ultraviolet (UV)-curable resin and ultrasound was investigated. A UV-curable gel film was formed on a glass plate having four lead zirconate titanate (PZT) transducers. Excitation of the transducers generated a lattice flexural vibration mode on the glass plate. The acoustic radiation force acted to deform the surface of the gel film, so that a lens array could be fabricated on the gel film. The lens array was exposed to UV light under ultrasonication to cure the UV-curable film. The quality factor of the transducer resonance was decreased upon curing of the resin film because the cured resin dampened the vibration of the plate. The acoustic characteristics of the UV-curable gel film were measured by using an ultrasound pulse technique at the MHz range. The sound speed of the gel increased from 987 to 1006 m/s (increase of 1.9%) as the UV exposure time increased. The attenuation coefficient also increased and the larger attenuation of the resin caused the lens array to have a lower quality factor.

  16. A novel liquid chromatography method using diode-array detector for the determination of oleuropein in dietary supplements.

    PubMed

    Bertolini, Tiziana; Vicentini, Lorenza; Boschetti, Silvia; Andreatta, Paolo; Gatti, Rita

    2016-09-10

    A simple and fast chromatographic method using ultraviolet diode-array detector (UV-DAD) was developed for the automatic high performance liquid chromatography (HPLC) determination of the title of oleuropein in a new dietary supplements in form of effervescent granules. The chromatographic separations were performed on a C18 core-shell column with detection at λ=232nm. The mobile phase consisted of deionized water with 0.1% TFA and acetonitrile under gradient conditions at a flow-rate of 0.8mL/min. Oleuropein and oleuroside present in the raw material were characterized by high performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). The validation of the analytical procedure has been performed determining the following parameters: specificity, linearity, repeatability, reproducibility, accuracy, limit of quantification (LOQ), stability of the standard and sample solutions. Linear response was observed in fortified placebo solutions (determination coefficient: 0.9998). Intra-day precision (relative standard deviation, RSD) was ≤5.0% for peak area and for retention times (tR) without significant differences between intra- and inter-day data. The limits of quantitation (LOQ) was about 5μg/mL and 9pmol/inject. Oleuropein recovery studies gave good results (99.9%) with a R.S.D. of 0.5%. The speed of analysis and the stability of the solutions with a fluctuation Δ (%) ≤2.0 at room temperature means an undoubted advantage of the method allowing the simultaneous preparation of many samples and consecutive chromatographic analyses by using an autosampler. The developed method is suitable for the quality control of oleuropein in raw material and industrial products. The method can be applied in any analytical laboratory not requiring a sophisticated instrumentation.

  17. Far field beam pattern of one MW combined beam of laser diode array amplifiers for space power transmission

    NASA Technical Reports Server (NTRS)

    Kwon, Jin H.; Lee, Ja H.

    1989-01-01

    The far-field beam pattern and the power-collection efficiency are calculated for a multistage laser-diode-array amplifier consisting of about 200,000 5-W laser diode arrays with random distributions of phase and orientation errors and random diode failures. From the numerical calculation it is found that the far-field beam pattern is little affected by random failures of up to 20 percent of the laser diodes with reference of 80 percent receiving efficiency in the center spot. The random differences in phases among laser diodes due to probable manufacturing errors is allowed to about 0.2 times the wavelength. The maximum allowable orientation error is about 20 percent of the diffraction angle of a single laser diode aperture (about 1 cm). The preliminary results indicate that the amplifier could be used for space beam-power transmission with an efficiency of about 80 percent for a moderate-size (3-m-diameter) receiver placed at a distance of less than 50,000 km.

  18. Individually-addressable flip-chip AlInGaN micropixelated light emitting diode arrays with high continuous and nanosecond output power.

    PubMed

    Zhang, H X; Massoubre, D; McKendry, J; Gong, Z; Guilhabert, B; Griffin, C; Gu, E; Jessop, P E; Girkin, J M; Dawson, M D

    2008-06-23

    Micropixelated blue (470 nm) and ultraviolet (370 nm) AlInGaN light emitting diode ('micro-LED') arrays have been fabricated in flip-chip format with different pixel diameters (72 microm and 30 microm at, respectively, 100 and 278 pixels/mm(2)). Each micro-LED pixel can be individually-addressed and the devices possess a specially designed n-common contact incorporated to ensure uniform current injection and consequently uniform light emission across the array. The flip-chip micro-LEDs show, per pixel, high continuous output intensity of up to 0.55 microW/microm(2) (55 W/cm(2)) at an injection current density of 10 kA/cm(2) and can sustain continuous injection current densities of up to 12 kA/cm(2) before breakdown. We also demonstrate that nanosecond pulsed output operation of these devices with per pixel onaxis average peak intensity up to 2.9 microW/microm(2) (corresponding to energy of 45pJ per 22ns optical pulse) can be achieved. We investigate the pertinent performance characteristics of these arrays for micro-projection applications, including the prospect of integrated optical pumping of organic semiconductor lasers.

  19. Improved characteristics of ultraviolet AlGaN multiple-quantum-well laser diodes with step-graded quantum barriers close to waveguide layers

    NASA Astrophysics Data System (ADS)

    Cai, Xuefen; Li, Shuping; Kang, Junyong

    2016-09-01

    Ultraviolet AlGaN multiple-quantum-well laser diodes (LDs) with step-graded quantum barriers (QBs) instead of conventional first and last QBs close to waveguide layers are proposed. The characteristics of this type of laser diodes are numerically investigated by using the software PICS3D and it is found that the performances of these LDs are greatly improved. The results indicates that the structure with step-graded QBs exhibits higher output light power, slope efficiency and emission intensity, as well as lower series resistance and threshold current density under the identical condition, compared with conventional LD structure.

  20. Direct spectroscopic measurement of packaging-induced strains in high-power laser diode arrays

    NASA Astrophysics Data System (ADS)

    Tomm, Jens W.; Mueller, Ralf; Baerwolff, A.; Neuner, M.; Elsaesser, Thomas; Lorenzen, Dirk; Daiminger, Franz X.; Gerhardt, A.; Donecker, J.

    1999-04-01

    High-power diode lasers such as `cm-bar arrays' are important for many applications. The `p-side down packaging', i.e. the direct mounting of the epitaxial layer sequence on a heat spreader ensures sufficient thermal properties, however, in such a geometry, additional mechanical strain of the active region represents a central issue, affecting both the laser parameter as well as lifetime and reliability of the device. Thermally induced strain caused by device packaging is studied in high-power semiconductor laser arrays by a novel non-invasive technique. Photocurrent measurements with intentionally strained laser array devices for 808 nm emission reveal spectral shifts of all allowed optical transitions in the active region. These shifts serve as a measure for strain and are compared with model calculations. Depending on the specific heat spreader materials we find compressive or tensile mounting induced strain contributions. For a given packaging architecture, about one quarter of the mounting induced strain is transferred to the quantum well region of the device. Spatially resolved measurements allow to measure lateral strain gradients in the devices. Using this data for calibration we show that polarization resolved electroluminescence scans can be used as convenient measure for strain homogeneity test also in quantum-well devices.

  1. Core-shell diode array for high performance particle detectors and imaging sensors: status of the development

    NASA Astrophysics Data System (ADS)

    Jia, G.; Hübner, U.; Dellith, J.; Dellith, A.; Stolz, R.; Plentz, J.; Andrä, G.

    2017-02-01

    We propose a novel high performance radiation detector and imaging sensor by a ground-breaking core-shell diode array design. This novel core-shell diode array are expected to have superior performance respect to ultrahigh radiation hardness, high sensitivity, low power consumption, fast signal response and high spatial resolution simultaneously. These properties are highly desired in fundamental research such as high energy physics (HEP) at CERN, astronomy and future x-ray based protein crystallography at x-ray free electron laser (XFEL) etc.. This kind of detectors will provide solutions for these fundamental research fields currently limited by instrumentations. In this work, we report our progress on the development of core-shell diode array for the applications as high performance imaging sensors and particle detectors. We mainly present our results in the preparation of high aspect ratio regular silicon rods by metal assisted wet chemical etching technique. Nearly 200 μm deep and 2 μm width channels with high aspect ratio have been etched into silicon. This result will open many applications not only for the core-shell diode array, but also for a high density integration of 3D microelectronics devices.

  2. High Power Laser Diode Array Qualification and Guidelines for Space Flight Environments

    NASA Technical Reports Server (NTRS)

    Ott, Melanie N.; Eegholm, Niels; Stephen, Mark; Leidecker, Henning; Plante, Jeannette; Meadows, Byron; Amzajerdian, Farzin; Jamison, Tracee; LaRocca, Frank

    2006-01-01

    High-power laser diode arrays (LDAs) are used for a variety of space-based remote sensor laser programs as an energy source for diode-pumped solid-state lasers. LDAs have been flown on NASA missions including MOLA, GLAS and MLA and have continued to be viewed as an important part of the laser-based instrument component suite. There are currently no military or NASA-grade, -specified, or - qualified LDAs available for "off-the-shelf" use by NASA programs. There has also been no prior attempt to define a standard screening and qualification test flow for LDAs for space applications. Initial reliability studies have also produced good results from an optical performance and stability standpoint. Usage experience has shown, howeve that the current designs being offered may be susceptible to catastrophic failures due to their physical construction (packaging) combined with the electro-optical operational modes and the environmental factors of space application. design combined with operational mode was at the root of the failures which have greatly reduced the functionality of the GLAS instrument. The continued need for LDAs for laser-based science instruments and past catastrophic failures of this part type demand examination of LDAs in a manner which enables NASA to select, buy, validate and apply them in a manner which poses as little risk to the success of the mission as possible.

  3. Stretchable, transparent graphene interconnects for arrays of microscale inorganic light emitting diodes on rubber substrates.

    PubMed

    Kim, Rak-Hwan; Bae, Myung-Ho; Kim, Dae Gon; Cheng, Huanyu; Kim, Bong Hoon; Kim, Dae-Hyeong; Li, Ming; Wu, Jian; Du, Frank; Kim, Hoon-Sik; Kim, Stanley; Estrada, David; Hong, Suck Won; Huang, Yonggang; Pop, Eric; Rogers, John A

    2011-09-14

    This paper describes the fabrication and design principles for using transparent graphene interconnects in stretchable arrays of microscale inorganic light emitting diodes (LEDs) on rubber substrates. We demonstrate several appealing properties of graphene for this purpose, including its ability to spontaneously conform to significant surface topography, in a manner that yields effective contacts even to deep, recessed device regions. Mechanics modeling reveals the fundamental aspects of this process, as well as the use of the same layers of graphene for interconnects designed to accommodate strains of 100% or more, in a completely reversible fashion. These attributes are compatible with conventional thin film processing and can yield high-performance devices in transparent layouts. Graphene interconnects possess attractive features for both existing and emerging applications of LEDs in information display, biomedical systems, and other environments.

  4. Tm,Ho:YLF laser end-pumped by a semiconductor diode laser array

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid (Inventor)

    1990-01-01

    An Ho:YLF crystal including Tm as sensitizers for the activator Ho, is optically pumped with a semiconductor diode laser array to generate 2.1 micron radiation with a pump power to output power of efficiency as high as 68 percent. The prior-art dual sensitizer system of Er and Tm requires cooling, such as by LN2, but by using Tm alone and decreasing the concentrations of Tm and Ho, and decreasing the length of the laser rod to about 1 cm, it has been demonstrated that laser operation can be obtained from a temperature of 77 K with an efficiency as high as 68 percent up to ambient room temperature with an efficiency at that temperature as high as 9 percent.

  5. DLTS Study of RIE-Induced Deep Levels in Si Using p+n Diode Arrays

    NASA Astrophysics Data System (ADS)

    Watanabe, Miyoko Oku; Taguchi, Minoru; Kanzaki, Koichi; Zohta, Yasuhito

    1983-02-01

    Deep levels in Si induced by reactive ion etching (RIE) of SiO2 film have been studied by DLTS. In order to detect the RIE-induced damage existing near the surface region, special device structures consisting of p+n diode arrays are used. It is found that the dominant deep levels produced by RIE are four hole traps. One level at Ev+0.40 eV exhibits the Poole-Frenkel effect, from which it is identified as an acceptor. Another level at Ev+0.46 eV is deduced to be an interstitial iron level from the emission rate. There is a strong decrease in the deep level concentrations upon annealing above 500°C. However, the deep levels do not completely disappear upon annealing at high temperatures. The deep level concentrations correlate well with the current-voltage characteristics of the devices.

  6. A Single-Photon Avalanche Diode Array for Fluorescence Lifetime Imaging Microscopy

    PubMed Central

    Schwartz, David Eric; Charbon, Edoardo; Shepard, Kenneth L.

    2013-01-01

    We describe the design, characterization, and demonstration of a fully integrated single-photon avalanche diode (SPAD) imager for use in time-resolved fluorescence imaging. The imager consists of a 64-by-64 array of active SPAD pixels and an on-chip time-to-digital converter (TDC) based on a delay-locked loop (DLL) and calibrated interpolators. The imager can perform both standard time-correlated single-photon counting (TCSPC) and an alternative gated-window detection useful for avoiding pulse pile-up when measuring bright signal levels. To illustrate the use of the imager, we present measurements of the decay lifetimes of fluorescent dyes of several types with a timing resolution of 350 ps. PMID:23976789

  7. Determination of phenolic compounds in Prunella L. by liquid chromatography-diode array detection.

    PubMed

    Sahin, Saliha; Demir, Cevdet; Malyer, Hulusi

    2011-07-15

    Four species of Prunella L. (Prunella vulgaris L., Prunella laciniata L., Prunella grandiflora L. and Prunella orientalis Bornm.) belong to the family of Lamiaceae and representing popular Western and Chinese herbal medicine were examined for the content of phenolic compounds. Phenolic acids (rosmarinic acid, caffeic acid, ferulic acid, chlorogenic acid, protocatechuic acid), flavonoids (rutin, quercetin) in different quantitative proportions depending on extracts were determined by the rapid, selective and accurate method combining solvent/acid hydrolysis extraction and high performance liquid chromatography-diode array detection (HPLC-DAD). Water, methanol, butanol, acetonitrile, ethyl acetate, hexane and their acidic solutions were used to examine the efficiency of different solvent systems for the extraction of phenolic compounds. Acid hydrolysis extraction was established as the most suitable extraction method for phenolic compounds.

  8. A Single-Photon Avalanche Diode Array for Fluorescence Lifetime Imaging Microscopy.

    PubMed

    Schwartz, David Eric; Charbon, Edoardo; Shepard, Kenneth L

    2008-11-21

    We describe the design, characterization, and demonstration of a fully integrated single-photon avalanche diode (SPAD) imager for use in time-resolved fluorescence imaging. The imager consists of a 64-by-64 array of active SPAD pixels and an on-chip time-to-digital converter (TDC) based on a delay-locked loop (DLL) and calibrated interpolators. The imager can perform both standard time-correlated single-photon counting (TCSPC) and an alternative gated-window detection useful for avoiding pulse pile-up when measuring bright signal levels. To illustrate the use of the imager, we present measurements of the decay lifetimes of fluorescent dyes of several types with a timing resolution of 350 ps.

  9. Efficient distributed control of light-emitting diode array lighting systems.

    PubMed

    Dong, Jianfei; Pandharipande, Ashish

    2012-07-15

    We consider illumination rendering with distributed control of a lighting system with an array of light-emitting diodes (LEDs). As low-cost microprocessors become standard components in LED drivers, distributing the computation of the control signals to individual LED drivers becomes attractive. Common distributed control algorithms require each individual controller to exchange information with all the others and process it. This incurs too large a communication and processing overhead for a low-cost local controller. In this Letter, we propose a distributed control algorithm for achieving global illumination rendering, wherein a controller only needs to communicate within a selected neighborhood. We present design criteria for defining the communication neighborhood and study its impact on rendering performance.

  10. Single-layer graphene-TiO2 nanotubes array heterojunction for ultraviolet photodetector application

    NASA Astrophysics Data System (ADS)

    Zhang, Deng-Yue; Ge, Cai-Wang; Wang, Jiu-Zhen; Zhang, Teng-Fei; Wu, Yu-Cheng; Liang, Feng-Xia

    2016-11-01

    In this work, we reported on the fabrication of a single-layer graphene (SLG)-TiO2 nanotube arrays (NTs) heterostructures ultraviolet photodetector (UVPD) by transferring chemical vapor deposition derived MLG on the surface of anodic TiO2NTs array. Through varying the annealing atmosphere and anodization time in the TiO2 synthesis procedure, the electronic and optoelectronic properties of the as-fabricated Schottky junction UVPD were studied. It was revealed that the anodic TiO2NTs annealed in air showed a better rectifying behavior and was highly sensitive to UV light irradiation. Further investigation found that the device performance of the UVPD can be readily modulated by the anodization time, and the anodic TiO2NTs with a medium tube length of 9.6 μm exhibits the highest device performance. These results demonstrated that the present SLG-TiO2NTs array hetero-junction UVPD will be highly promising for fabricating high-performance optoelectronic device and system in the future.

  11. A superconducting focal plane array for ultraviolet, optical, and near-infrared astrophysics.

    PubMed

    Mazin, Benjamin A; Bumble, Bruce; Meeker, Seth R; O'Brien, Kieran; McHugh, Sean; Langman, Eric

    2012-01-16

    Microwave Kinetic Inductance Detectors, or MKIDs, have proven to be a powerful cryogenic detector technology due to their sensitivity and the ease with which they can be multiplexed into large arrays. A MKID is an energy sensor based on a photon-variable superconducting inductance in a lithographed microresonator, and is capable of functioning as a photon detector across the electromagnetic spectrum as well as a particle detector. Here we describe the first successful effort to create a photon-counting, energy-resolving ultraviolet, optical, and near infrared MKID focal plane array. These new Optical Lumped Element (OLE) MKID arrays have significant advantages over semiconductor detectors like charge coupled devices (CCDs). They can count individual photons with essentially no false counts and determine the energy and arrival time of every photon with good quantum efficiency. Their physical pixel size and maximum count rate is well matched with large telescopes. These capabilities enable powerful new astrophysical instruments usable from the ground and space. MKIDs could eventually supplant semiconductor detectors for most astronomical instrumentation, and will be useful for other disciplines such as quantum optics and biological imaging.

  12. Analyzing the performance of ArcCHECK diode array detector for VMAT plan

    PubMed Central

    Thiyagarajan, Rajesh; Nambiraj, Arunai; Sinha, Sujit Nath; Yadav, Girigesh; Kumar, Ashok; Subramani, Vikraman; Kothandaraman

    2016-01-01

    Aim The aim of this study is to evaluate performance of ArcCHECK diode array detector for the volumetric modulated arc therapy (VMAT) patient specific quality assurance (QA). VMAT patient specific QA results were correlated with ion chamber measurement. Dose response of the ArcCHECK detector was studied. Background VMAT delivery technique improves the dose distribution. It is complex in nature and requires proper QA before its clinical implementation. ArcCHECK is a novel three dimensional dosimetry system. Materials and methods Twelve retrospective VMAT plans were calculated on ArcCHECK phantom. Point dose and dose map were measured simultaneously with ion chamber (IC-15) and ArcCHECK diode array detector, respectively. These measurements were compared with their respective TPS calculated values. Results The ion chamber measurements are in good agreement with TPS calculated doses. Mean difference between them is 0.50% with standard deviation of 0.51%. Concordance correlation coefficient (CCC) obtained for ion chamber measurements is 0.9996. These results demonstrate a strong correlation between the absolute dose predicted by our TPS and the measured dose. The CCC between ArcCHECK doses and TPS predictions on the CAX was found to be 0.9978. In gamma analysis of dose map, the mean passing rate was 98.53% for 3% dose difference and 3 mm distance to agreement. Conclusions The VMAT patient specific QA with an ion chamber and ArcCHECK phantom are consistent with the TPS calculated dose. Statistically good agreement was observed between ArcCHECK measured and TPS calculated. Hence, it can be used for routine VMAT QA. PMID:26900358

  13. High-performance thin layer chromatography using fiber optics and diode-array detection

    NASA Astrophysics Data System (ADS)

    Spangenberg, Bernd; Klein, Karl-Friedrich; Mannhardt, J.

    2002-06-01

    HPTLC (High Performance Thin Layer Chromatography) is a well known and versatile separation method which shows a lot of advantages and options in comparison to other separation techniques. The method is fast and inexpensive and does not need time-consuming pretreatments. Using fiber-optic elements for controlled light-guiding, the TLC-method was significantly improved: the new HPTLC-system is able to measure simultaneously at different wavelengths without destroying the plate surface or the analytes on the surface. For registration of the sample distribution on a HPTLC-plate we developed a new and sturdy diode-array HPTLC- scanner which allows registration of spectra on the TLC- plates in the range of 198 nm to 610 nm with a spectral resolution better than 1.2 nm. The spatial resolution on plate is better than 160 micrometers . In the spectral mode, the new HPTLC-scanner delivers much more information than the commonly used TLC-scanner. The measurement of 450 spectra of one separation track does not need more than three minutes. However, in the fixed wavelength mode the contour plot can be measured within 15 seconds. In this case, the signal will be summarized and averaged over a spectral range having FWHM from 10 nm to 25 nm depending on the substance under test. The new diode-array HPTLC-scanner makes various chemometric applications possible. The new method can be used easily in clinical diagnostic systems easily, e.g. for blood and uring investigations. In addition, new applications are possible. For example, the rich structured PAHs were studied. Although the separation is incomplete the 16 compounds can be quantified using suitable wavelengths.

  14. Coal liquefaction process streams characterization and evaluation: High performance liquid chromatography (HPLC) of coal liquefaction process streams using normal-phase separation with uv diode array detection

    SciTech Connect

    Clifford, D.J.; McKinney, D.E.; Hou, Lei; Hatcher, P.G.

    1994-01-01

    This study demonstrated the considerable potential of using two-dimensional, high performance liquid chromatography (HPLC) with normal-phase separation and ultraviolet (UV) diode array detection for the examination of filtered process liquids and the 850{degrees}F{sup {minus}} distillate materials derived from direct coal liquefaction process streams. A commercially available HPLC column (Hypersil Green PAH-2) provided excellent separation of the complex mixture of polynuclear aromatic hydrocarbons (PAHs) found in coal-derived process streams process. Some characteristics of the samples delineated by separation could be attributed to processing parameters. Mass recovery of the process derived samples was low (5--50 wt %). Penn State believes, however, that, improved recovery can be achieved. High resolution mass spectrometry and gas chromatography/mass spectrometry (GC/MS) also were used in this study to characterize the samples and the HPLC fractions. The GC/MS technique was used to preliminarily examine the GC-elutable portion of the samples. The GC/MS data were compared with the data from the HPLC technique. The use of an ultraviolet detector in the HPLC work precludes detecting the aliphatic portion of the sample. The GC/MS allowed for identification and quantification of that portion of the samples. Further development of the 2-D HPLC analytical method as a process development tool appears justified based on the results of this project.

  15. Quality assurance of asymmetric jaw alignment using 2D diode array

    SciTech Connect

    Kim, Sun Mo; Yeung, Ivan W. T.; Moseley, Douglas J.

    2013-12-15

    Purpose: A method using a 2D diode array is proposed to measure the junction gap (or overlap) and dose with high precision for routine quality assurance of the asymmetric jaw alignment.Methods: The central axis (CAX) of the radiation field was determined with a 15 × 15 cm{sup 2} photon field at four cardinal collimator angles so that the junction gap (or overlap) can be measured with respect to the CAX. Two abutting fields having a field size of 15 cm (length along the axis parallel to the junction) × 7.5 cm (width along the axis perpendicular to the junction) were used to irradiate the 2D diode array (MapCHECK2) with 100 MU delivered at the photon energy of 6 MV. The collimator was slightly rotated at 15° with respect to the beam central axis to increase the number of diodes effective on the measurement of junction gap. The junction gap and dose measured in high spatial resolution were compared to the conventional methods using an electronic portal imaging device (EPID) and radiochromic film, respectively. In addition, the reproducibility and sensitivity of the proposed method to the measurements of junction gap and dose were investigated.Results: The junction gap (or overlap) and dose measured by MapCHECK2 agreed well to those measured by the conventional methods of EPID and film (the differences ranged from −0.01 to 0 cm and from −1.34% to 0.6% for the gap and dose, respectively). No variation in the repeat measurements of the junction gap was found whereas the measurements of junction dose were found to vary in quite a small range over the days of measurement (0.21%–0.35%). While the sensitivity of the measured junction gap to the actual junction gap applied was the ideal value of 1 cm/cm as expected, the sensitivity of the junction dose to the actual junction gap increased as the junction gap (or overlap) decreased (maximum sensitivity: 201.7%/cm).Conclusions: The initial results suggest that the method is applicable for a comprehensive quality

  16. Dual-Channel Extraordinary Ultraviolet Transmission through an Aluminum Nanohole Array.

    PubMed

    Hu, Jinlian; Shen, Maozhen; Li, Zhigang; Li, Xinhua; Liu, Guangqiang; Kan, Cai-Xia; Wang, Xiangdong; Li, Yue

    2017-03-30

    Ultraviolet (UV) surface plasmon has distinct applications in UV filter, high density optical storage, spectral enhancement, optical detector and nanolithography, which are closely related to the plasmon-induced extraordinary optical transmission (EOT). However, such EOT in the UV region has not been detailedly researched. We report the UV transmission of based on the theoretical research using finite-difference time-domain (FDTD) method, by modulating Al thickness, hole size, array periodicity, and SiO2 overlayer thickness. It is notable that we can obtain dual-channel UV transmission peaks with excellent qualities such as high transmissivity, zero cross-talk, narrow bandwidth and perfect symmetry, by optimizing parameters. The UV transmission peaks have been discovered to non-monotonously shift with increasing hole size. Though array periodicity has great influence on the transmission peak position, the peak energy in the UV region is much less than that value predicted by the well known periodicity-related surface plasmon polariton (SPP) wavelength equation; the energy discrepancy in UV region can reach above 20%, which is much larger than that value (typically 4%) in the visible-infrared region. Further, SiO2 overlayer may significantly modify the transmission properties. The Al nanohole arrays have also been found to exhibit distinct multi-band UV electric field enhancement properties with special interface effect and size effect. Such extraordinary dual-channel UV transmission with zero cross-talk, based on a very simple Al nanohole array, has promising uses in dual-channel UV filter, high density optical storage, and plasmon-enhanced fluorescence/Raman spectroscopy, since which generally involve two wavebands (writing/reading storage or exciting/emission wavelengths). This study would be expected to expand our fundamental understanding of the UV EOT phenomenon, and provide references for experimental research and application of deep-UV and near-UV involved

  17. A 48-pixel array of Single Photon Avalanche Diodes for multispot Single Molecule analysis.

    PubMed

    Gulinatti, Angelo; Rech, Ivan; Maccagnani, Piera; Ghioni, Massimo

    2013-02-04

    In this paper we present an array of 48 Single Photon Avalanche Diodes (SPADs) specifically designed for multispot Single Molecule Analysis. The detectors have been arranged in a 12×4 square geometry with a pitch-to-diameter ratio of ten in order to minimize the collection of the light from non-conjugated excitation spots. In order to explore the trade-offs between the detectors' performance and the optical coupling with the experimental setup, SPADs with an active diameter of 25 and of 50µm have been manufactured. The use of a custom technology, specifically designed for the fabrication of the detectors, allowed us to combine a high photon detection efficiency (peak close to 50% at a wavelength of 550nm) with a low dark count rate compatible with true single molecule detection. In order to allow easy integration into the optical setup for parallel single-molecule analysis, the SPAD array has been incorporated in a compact module containing all the electronics needed for a proper operation of the detectors.

  18. Tunable, full-color nanowire light emitting diode arrays monolithically integrated on Si and sapphire

    NASA Astrophysics Data System (ADS)

    Wang, Renjie; Ra, Yong-Ho; Wu, Yuanpeng; Zhao, Songrui; Nguyen, Hieu P. T.; Shih, Ishiang; Mi, Zetian

    2016-02-01

    The monolithic integration of red, green and blue (RGB) GaN-based light-emitting diodes (LEDs) directly on a single chip is critically important for smart lighting and full color display applications. In this work, RGB InGaN/GaN dot-in-a-wire LED arrays were laterally arranged on a Si wafer using a three-step SiOx-mask selective area growth (SAG) technique, and on a sapphire wafer using a Ti-mask SAG technique. Tunable emission across the entire visible spectral range (~ 450 nm to 700 nm) can be readily achieved on a single Si wafer by varying the sizes and/or compositions of the dots. By separately biasing lateral-arranged multi-color LED subpixels, the correlated color temperature (CCT) values of such a ~ 0.016 mm2 pixel can be varied from ~ 1900 K to 6800 K. The RGB pixel size can be further reduced by using the Ti-mask SAG technique on sapphire wafer. Full-color InGaN/GaN nanowire arrays with sizes of 2.8 × 2.8 μm2 have been monolithically fabricated into the same pixel.

  19. Ultraviolet-enhanced light emitting diode employing individual ZnO microwire with SiO{sub 2} barrier layers

    SciTech Connect

    Xu, Yingtian; Xu, Li; Dai, Jun; Ma, Yan; Chu, Xianwei; Zhang, Yuantao; Du, Guotong; Zhang, Baolin; Yin, Jingzhi

    2015-05-25

    This paper details the fabrication of n-ZnO single microwire (SMW)-based high-purity ultraviolet light-emitting diodes (UV-LEDs) with an added SiO{sub 2} barrier layer on the p-Si substrate. However, the current-voltage (I-V) curve exhibited non-ideal rectifying characteristics. Under forward bias, both UV and visible emissions could be detected by electroluminescence (EL) measurement. When bias voltage reached 60 V at room temperature, a UV emission spike occurred at 390 nm originating from the n-ZnO SMW. Compared with the EL spectrum of the n-ZnO SMW/p-Si heterojunction device without the SiO{sub 2} barrier layer, we saw improved UV light extraction efficiency from the current-blocking effect of the SiO{sub 2} layer. The intense UV emission in the n-ZnO SMW/SiO{sub 2}/p-Si heterojunction indicated that the SiO{sub 2} barrier layer can restrict the movement of electrons as expected and result in effective electron-hole recombination in ZnO SMW.

  20. Indium gallium nitride-based ultraviolet, blue, and green light-emitting diodes functionalized with shallow periodic hole patterns

    PubMed Central

    Jeong, Hyun; Salas-Montiel, Rafael; Lerondel, Gilles; Jeong, Mun Seok

    2017-01-01

    In this study, we investigated the improvement in the light output power of indium gallium nitride (InGaN)-based ultraviolet (UV), blue, and green light-emitting diodes (LEDs) by fabricating shallow periodic hole patterns (PHPs) on the LED surface through laser interference lithography and inductively coupled plasma etching. Noticeably, different enhancements were observed in the light output powers of the UV, blue, and green LEDs with negligible changes in the electrical properties in the light output power versus current and current versus voltage curves. In addition, confocal scanning electroluminescence microscopy is employed to verify the correlation between the enhancement in the light output power of the LEDs with PHPs and carrier localization of InGaN/GaN multiple quantum wells. Light propagation through the PHPs on the UV, blue, and green LEDs is simulated using a three-dimensional finite-difference time-domain method to confirm the experimental results. Finally, we suggest optimal conditions of PHPs for improving the light output power of InGaN LEDs based on the experimental and theoretical results. PMID:28374856

  1. Indium gallium nitride-based ultraviolet, blue, and green light-emitting diodes functionalized with shallow periodic hole patterns.

    PubMed

    Jeong, Hyun; Salas-Montiel, Rafael; Lerondel, Gilles; Jeong, Mun Seok

    2017-04-04

    In this study, we investigated the improvement in the light output power of indium gallium nitride (InGaN)-based ultraviolet (UV), blue, and green light-emitting diodes (LEDs) by fabricating shallow periodic hole patterns (PHPs) on the LED surface through laser interference lithography and inductively coupled plasma etching. Noticeably, different enhancements were observed in the light output powers of the UV, blue, and green LEDs with negligible changes in the electrical properties in the light output power versus current and current versus voltage curves. In addition, confocal scanning electroluminescence microscopy is employed to verify the correlation between the enhancement in the light output power of the LEDs with PHPs and carrier localization of InGaN/GaN multiple quantum wells. Light propagation through the PHPs on the UV, blue, and green LEDs is simulated using a three-dimensional finite-difference time-domain method to confirm the experimental results. Finally, we suggest optimal conditions of PHPs for improving the light output power of InGaN LEDs based on the experimental and theoretical results.

  2. The role of graphene formed on silver nanowire transparent conductive electrode in ultra-violet light emitting diodes

    PubMed Central

    Seo, Tae Hoon; Lee, Seula; Min, Kyung Hyun; Chandramohan, S.; Park, Ah Hyun; Lee, Gun Hee; Park, Min; Suh, Eun-Kyung; Kim, Myung Jong

    2016-01-01

    This paper reports a highly reliable transparent conductive electrode (TCE) that integrates silver nanowires (AgNWs) and high-quality graphene as a protecting layer. Graphene with minimized defects and large graphene domains has been successfully obtained through a facile two-step growth approach. Ultraviolet light emitting diodes (UV-LEDs) were fabricated with AgNWs or hybrid electrodes where AgNWs were combined with two-step grown graphene (A-2GE) or conventional one-step grown graphene (A-1GE). The device performance and reliability of the UV-LEDs with three different electrodes were compared. The A-2GE offered high figure of merit owing to the excellent UV transmittance and reduced sheet resistance. As a consequence, the UV-LEDs made with A-2GE demonstrated reduced forward voltage, enhanced electroluminescence (EL) intensity, and alleviated efficiency droop. The effects of joule heating and UV light illumination on the electrode stability were also studied. The present findings prove superior performance of the A-2GE under high current injection and continuous operation of UV LED, compared to other electrodes. From our observation, the A-2GE would be a reliable TCE for high power UV-LEDs. PMID:27387274

  3. Time Effectiveness of Ultraviolet C Light (UVC) Emitted by Light Emitting Diodes (LEDs) in Reducing Stethoscope Contamination

    PubMed Central

    Messina, Gabriele; Fattorini, Mattia; Nante, Nicola; Rosadini, Daniele; Serafini, Andrea; Tani, Marco; Cevenini, Gabriele

    2016-01-01

    Today it is well demonstrated that stethoscopes can be as contaminated as hands, which are a recognized source of Health-Care Associated Infections (HCAIs). Ultraviolet C (UVC) light has proven disinfection capacity and the innovative UVC technology of Light Emitting Diode (LED) shows several potential benefits. To verify whether the use of UVC LEDs is effective and reliable in stethoscope membrane disinfection after prolonged use, a pre-post intervention study was conducted. A total of 1668 five-minute cycles were performed on two UVC LEDs to simulate their use; thereafter, their disinfection capacity was tested on stethoscope membranes used on a previously auscultated volunteer. Then, a further 1249 cycles were run and finally the LEDs were tested to assess performance in reducing experimental contamination by Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli on the stethoscope membrane. Baseline volunteer contamination identified 104 Colony Forming Units (CFUs) while treated Petri dishes had 12 and 15 CFUs (p < 0.001). Statistically significant differences (p < 0.001) were also found relating to the reduction of specific bacteria: in particular, after treatment no CFU were observed for S. aureus and E. coli. UVC LEDs demonstrated the capacity to maintain high levels of disinfection after more than 240 h of use and they were effective against common microorganisms that are causative agents of HCAIs. PMID:27669273

  4. Photovoltaic powered ultraviolet and visible light-emitting diodes for sustainable point-of-use disinfection of drinking waters.

    PubMed

    Lui, Gough Yumu; Roser, David; Corkish, Richard; Ashbolt, Nicholas; Jagals, Paul; Stuetz, Richard

    2014-09-15

    For many decades, populations in rural and remote developing regions will be unable to access centralised piped potable water supplies, and indeed, decentralised options may be more sustainable. Accordingly, improved household point-of-use (POU) disinfection technologies are urgently needed. Compared to alternatives, ultraviolet (UV) light disinfection is very attractive because of its efficacy against all pathogen groups and minimal operational consumables. Though mercury arc lamp technology is very efficient, it requires frequent lamp replacement, involves a toxic heavy metal, and their quartz envelopes and sleeves are expensive, fragile and require regular cleaning. An emerging alternative is semiconductor-based units where UV light emitting diodes (UV-LEDs) are powered by photovoltaics (PV). Our review charts the development of these two technologies, their current status, and challenges to their integration and POU application. It explores the themes of UV-C-LEDs, non-UV-C LED technology (e.g. UV-A, visible light, Advanced Oxidation), PV power supplies, PV/LED integration and POU suitability. While UV-C LED technology should mature in the next 10 years, research is also needed to address other unresolved barriers to in situ application as well as emerging research opportunities especially UV-A, photocatalyst/photosensitiser use and pulsed emission options.

  5. Time Effectiveness of Ultraviolet C Light (UVC) Emitted by Light Emitting Diodes (LEDs) in Reducing Stethoscope Contamination.

    PubMed

    Messina, Gabriele; Fattorini, Mattia; Nante, Nicola; Rosadini, Daniele; Serafini, Andrea; Tani, Marco; Cevenini, Gabriele

    2016-09-23

    Today it is well demonstrated that stethoscopes can be as contaminated as hands, which are a recognized source of Health-Care Associated Infections (HCAIs). Ultraviolet C (UVC) light has proven disinfection capacity and the innovative UVC technology of Light Emitting Diode (LED) shows several potential benefits. To verify whether the use of UVC LEDs is effective and reliable in stethoscope membrane disinfection after prolonged use, a pre-post intervention study was conducted. A total of 1668 five-minute cycles were performed on two UVC LEDs to simulate their use; thereafter, their disinfection capacity was tested on stethoscope membranes used on a previously auscultated volunteer. Then, a further 1249 cycles were run and finally the LEDs were tested to assess performance in reducing experimental contamination by Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli on the stethoscope membrane. Baseline volunteer contamination identified 104 Colony Forming Units (CFUs) while treated Petri dishes had 12 and 15 CFUs (p < 0.001). Statistically significant differences (p < 0.001) were also found relating to the reduction of specific bacteria: in particular, after treatment no CFU were observed for S. aureus and E. coli. UVC LEDs demonstrated the capacity to maintain high levels of disinfection after more than 240 h of use and they were effective against common microorganisms that are causative agents of HCAIs.

  6. Calibration of optimal use parameters for an ultraviolet light-emitting diode in eliminating bacterial contamination on needleless connectors

    PubMed Central

    Hutchens, M.P.; Drennan, S.L.; Cambronne, E.D.

    2015-01-01

    Aims Needleless connectors may develop bacterial contamination and cause central-line-associated bloodstream infections (CLABSI) despite rigorous application of best-practice. Ultraviolet (UV) light-emitting diodes (LED) are an emerging, increasingly affordable disinfection technology. We tested the hypothesis that a low-power UV LED could reliably eliminate bacteria on needleless central-line ports in a laboratory model of central-line contamination. Methods and Results Needleless central-line connectors were inoculated with Staphylococcus aureus. A 285 nm UV LED was used in calibrated fashion to expose contaminated connectors. Ports were directly applied to agar plates and flushed with sterile saline, allowing assessment of bacterial survival on the port surface and in simulated usage flow-through fluid. UV applied to needleless central-line connectors was highly lethal at 0·5 cm distance at all tested exposure times. At distances >1·5 cm both simulated flow-through and port surface cultures demonstrated significant bacterial growth following UV exposure. Logarithmic-phase S. aureus subcultures were highly susceptible to UV induction/maintenance dosing. Conclusions Low-power UV LED doses at fixed time and distance from needleless central-line connector ports reduced cultivable S. aureus from >106 CFU to below detectable levels in this laboratory simulation of central-line port contamination. Significance and Impact of the study Low-power UV LEDs may represent a feasible alternative to current best-practice in connector decontamination. PMID:25801979

  7. The role of graphene formed on silver nanowire transparent conductive electrode in ultra-violet light emitting diodes

    NASA Astrophysics Data System (ADS)

    Seo, Tae Hoon; Lee, Seula; Min, Kyung Hyun; Chandramohan, S.; Park, Ah Hyun; Lee, Gun Hee; Park, Min; Suh, Eun-Kyung; Kim, Myung Jong

    2016-07-01

    This paper reports a highly reliable transparent conductive electrode (TCE) that integrates silver nanowires (AgNWs) and high-quality graphene as a protecting layer. Graphene with minimized defects and large graphene domains has been successfully obtained through a facile two-step growth approach. Ultraviolet light emitting diodes (UV-LEDs) were fabricated with AgNWs or hybrid electrodes where AgNWs were combined with two-step grown graphene (A-2GE) or conventional one-step grown graphene (A-1GE). The device performance and reliability of the UV-LEDs with three different electrodes were compared. The A-2GE offered high figure of merit owing to the excellent UV transmittance and reduced sheet resistance. As a consequence, the UV-LEDs made with A-2GE demonstrated reduced forward voltage, enhanced electroluminescence (EL) intensity, and alleviated efficiency droop. The effects of joule heating and UV light illumination on the electrode stability were also studied. The present findings prove superior performance of the A-2GE under high current injection and continuous operation of UV LED, compared to other electrodes. From our observation, the A-2GE would be a reliable TCE for high power UV-LEDs.

  8. Physics and polarization characteristics of 298 nm AlN-delta-GaN quantum well ultraviolet light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Liu, Cheng; Ooi, Yu Kee; Islam, S. M.; Verma, Jai; Xing, Huili Grace; Jena, Debdeep; Zhang, Jing

    2017-02-01

    This work investigates the physics and polarization characteristics of 298 nm AlN-delta-GaN quantum well (QW) ultraviolet (UV) light-emitting diodes (LEDs). The physics analysis shows that the use of the AlN-delta-GaN QW structure can ensure dominant conduction band (C) to heavy-hole (HH) subband transition and significantly improve the electron and top HH subband wave function overlap. As a result, up to 30-times enhancement in the transverse-electric (TE)-polarized spontaneous emission rate of the proposed structure can be obtained as compared to a conventional AlGaN QW structure. The polarization properties of molecular beam epitaxy-grown AlN/GaN QW-like UV LEDs, which consist of 3-4 monolayer (QW-like) delta-GaN layers sandwiched by 2.5-nm AlN sub-QW layers, are investigated in this study. The polarization-dependent electroluminescence measurement results are consistent with the theoretical analysis. Specifically, the TE-polarized emission intensity is measured to be much larger than the transverse-magnetic emission, indicating significant potential for our proposed QW structure for high-efficiency TE-polarized mid-UV LEDs.

  9. Strongly transverse-electric-polarized emission from deep ultraviolet AlGaN quantum well light emitting diodes

    SciTech Connect

    Reich, Christoph Guttmann, Martin; Wernicke, Tim; Mehnke, Frank; Kuhn, Christian; Feneberg, Martin; Goldhahn, Rüdiger; Rass, Jens; Kneissl, Michael; Lapeyrade, Mickael; Einfeldt, Sven; Knauer, Arne; Kueller, Viola; Weyers, Markus

    2015-10-05

    The optical polarization of emission from ultraviolet (UV) light emitting diodes (LEDs) based on (0001)-oriented Al{sub x}Ga{sub 1−x}N multiple quantum wells (MQWs) has been studied by simulations and electroluminescence measurements. With increasing aluminum mole fraction in the quantum well x, the in-plane intensity of transverse-electric (TE) polarized light decreases relative to that of the transverse-magnetic polarized light, attributed to a reordering of the valence bands in Al{sub x}Ga{sub 1−x}N. Using k ⋅ p theoretical model calculations, the AlGaN MQW active region design has been optimized, yielding increased TE polarization and thus higher extraction efficiency for bottom-emitting LEDs in the deep UV spectral range. Using (i) narrow quantum wells, (ii) barriers with high aluminum mole fractions, and (iii) compressive growth on patterned aluminum nitride sapphire templates, strongly TE-polarized emission was observed at wavelengths as short as 239 nm.

  10. Comparison of ultraviolet light-emitting diodes and low-pressure mercury-arc lamps for disinfection of water.

    PubMed

    Sholtes, Kari A; Lowe, Kincaid; Walters, Glenn W; Sobsey, Mark D; Linden, Karl G; Casanova, Lisa M

    2016-09-01

    Ultraviolet (UV) light-emitting diodes (LEDs) emitting at 260 nm were evaluated to determine the inactivation kinetics of bacteria, viruses, and spores compared to low-pressure (LP) UV irradiation. Test microbes were Escherichia coli B, a non-enveloped virus (MS-2), and a bacterial spore (Bacillus atrophaeus). For LP UV, 4-log10 reduction doses were: E. coli B, 6.5 mJ/cm(2); MS-2, 59.3 mJ/cm(2); and B. atrophaeus, 30.0 mJ/cm(2). For UV LEDs, the 4-log10 reduction doses were E. coli B, 6.2 mJ/cm(2); MS-2, 58 mJ/cm(2); and B. atrophaeus, 18.7 mJ/cm(2). Microbial inactivation kinetics of the two UV technologies were not significantly different for E. coli B and MS-2, but were different for B. atrophaeus spores. UV LEDs at 260 nm are at least as effective for inactivating microbes in water as conventional LP UV sources and should undergo further development in treatment systems to disinfect drinking water.

  11. The role of graphene formed on silver nanowire transparent conductive electrode in ultra-violet light emitting diodes.

    PubMed

    Seo, Tae Hoon; Lee, Seula; Min, Kyung Hyun; Chandramohan, S; Park, Ah Hyun; Lee, Gun Hee; Park, Min; Suh, Eun-Kyung; Kim, Myung Jong

    2016-07-08

    This paper reports a highly reliable transparent conductive electrode (TCE) that integrates silver nanowires (AgNWs) and high-quality graphene as a protecting layer. Graphene with minimized defects and large graphene domains has been successfully obtained through a facile two-step growth approach. Ultraviolet light emitting diodes (UV-LEDs) were fabricated with AgNWs or hybrid electrodes where AgNWs were combined with two-step grown graphene (A-2GE) or conventional one-step grown graphene (A-1GE). The device performance and reliability of the UV-LEDs with three different electrodes were compared. The A-2GE offered high figure of merit owing to the excellent UV transmittance and reduced sheet resistance. As a consequence, the UV-LEDs made with A-2GE demonstrated reduced forward voltage, enhanced electroluminescence (EL) intensity, and alleviated efficiency droop. The effects of joule heating and UV light illumination on the electrode stability were also studied. The present findings prove superior performance of the A-2GE under high current injection and continuous operation of UV LED, compared to other electrodes. From our observation, the A-2GE would be a reliable TCE for high power UV-LEDs.

  12. Improved output power of GaN-based ultraviolet light-emitting diodes with sputtered AlN nucleation layer

    NASA Astrophysics Data System (ADS)

    Chiu, C. H.; Lin, Y. W.; Tsai, M. T.; Lin, B. C.; Li, Z. Y.; Tu, P. M.; Huang, S. C.; Hsu, Earl; Uen, W. Y.; Lee, W. I.; Kuo, H. C.

    2015-03-01

    In this work, the ultraviolet light-emitting diodes (UV-LEDs) at 380 nm were grown on patterned sapphire substrate (PSS) by atmospheric pressure metal organic chemical vapor deposition (AP-MOCVD). A sputtered AlN nucleation layer was utilized on the PSS to enhance the quality of the epitaxial layer. By using high-resolution X-ray diffraction, the full-width at half-maximum of the rocking curve shows that the UV-LEDs with sputtered AlN nucleation layer had better crystalline quality when compared to conventional GaN nucleation samples. From the scanning electron microscope (SEM) and transmission electron microscopy (TEM) images, it can be observed that the tip and sidewall portion of the pattern was smooth using the sputtered AlN nucleation layer. The threading dislocation densities (TDDs) are reduced from 6×107 cm-2 to 2.5×107 cm-2 at the interface between the u-GaN layers for conventional and AlN PSS devices, respectively. As a result, a much higher light output power was achieved. The light output power at an injection current of 20 mA was enhanced by 30%. Further photoluminescence (PL) measurement and numerical simulation confirm that this increase of output power can be attributed to the improvement of material quality and light extraction.

  13. Proposed Use of Zero Bias Diode Arrays as Thermal Electric Noise Rectifiers and Non-Thermal Energy Harvesters

    NASA Astrophysics Data System (ADS)

    Valone, Thomas F.

    2009-03-01

    The well known built-in voltage potential for some select semiconductor p-n junctions and various rectifying devices is proposed to be favorable for generating DC electricity at "zero bias" (with no DC bias voltage applied) in the presence of Johnson noise or 1/f noise which originates from the quantum vacuum (Koch et al., 1982). The 1982 Koch discovery that certain solid state devices exhibit measurable quantum noise has also recently been labeled a finding of dark energy in the lab (Beck and Mackey, 2004). Tunnel diodes are a class of rectifiers that are qualified and some have been credited with conducting only because of quantum fluctuations. Microwave diodes are also good choices since many are designed for zero bias operation. A completely passive, unamplified zero bias diode converter/detector for millimeter (GHz) waves was developed by HRL Labs in 2006 under a DARPA contract, utilizing a Sb-based "backward tunnel diode" (BTD). It is reported to be a "true zero-bias diode." It was developed for a "field radiometer" to "collect thermally radiated power" (in other words, 'night vision'). The diode array mounting allows a feed from horn antenna, which functions as a passive concentrating amplifier. An important clue is the "noise equivalent power" of 1.1 pW per root hertz and the "noise equivalent temperature difference" of 10° K, which indicate sensitivity to Johnson noise (Lynch, et al., 2006). There also have been other inventions such as "single electron transistors" that also have "the highest signal to noise ratio" near zero bias. Furthermore, "ultrasensitive" devices that convert radio frequencies have been invented that operate at outer space temperatures (3 degrees above zero point: 3° K). These devices are tiny nanotech devices which are suitable for assembly in parallel circuits (such as a 2-D array) to possibly produce zero point energy direct current electricity with significant power density (Brenning et al., 2006). Photovoltaic p-n junction

  14. Exceeding 4% external quantum efficiency in ultraviolet organic light-emitting diode using PEDOT:PSS/MoOx double-stacked hole injection layer

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaowen; You, Fengjiao; Liu, Shiqi; Mo, Bingjie; Zhang, Zheling; Xiong, Jian; Cai, Ping; Xue, Xiaogang; Zhang, Jian; Wei, Bin

    2017-01-01

    An effective and simple method has been explored to construct an efficient ultraviolet organic light-emitting diode (OLED) by incorporating poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/MoOx double-stacked hole injection layer (HIL) and slightly retarding electron injection for achieving extremely balanced charge carriers. The device produces 4.6% external quantum efficiency with an attractive ultraviolet emission peak of 377 nm and full width at half maximum of 35 nm. Ultraviolet photoelectron spectroscopy and impedance spectroscopy analysis determine the substantially enhanced hole injection capacity of PEDOT:PSS/MoOx double-stacked HIL, which accordingly contributes to optimizing carrier balance. The results pave a way to advancing OLED in potential application towards short wavelength emission.

  15. High speed GaN micro-light-emitting diode arrays for data communications

    NASA Astrophysics Data System (ADS)

    Watson, Scott; McKendry, Jonathan J. D.; Zhang, Shuailong; Massoubre, David; Rae, Bruce R.; Green, Richard P.; Gu, Erdan; Henderson, Robert K.; Kelly, A. E.; Dawson, Martin D.

    2012-10-01

    Micro light-emitting diode (micro-LED) arrays based on an AlInGaN structure have attracted much interest recently as light sources for data communications. Visible light communication (VLC), over free space or plastic optical fibre (POF), has become a very important technique in the role of data transmission. The micro-LEDs which are reported here contain pixels ranging in diameter from 14 to 84μm and can be driven directly using a high speed probe or via complementary metal-oxide semiconductor (CMOS) technology. The CMOS arrays allow for easy, computer control of individual pixels within arrays containing up to 16×16 elements. The micro-LEDs best suited for data transmission have peak emissions of 450nm or 520nm, however various other wavelengths across the visible spectrum can also be used. Optical modulation bandwidths of over 400MHz have been achieved as well as error-free (defined as an error rate of <1x10-10) data transmission using on-off keying (OOK) non-return-to-zero (NRZ) modulation at data rates of over 500Mbit/s over free space. Also, as a step towards a more practical multi-emitter data transmitter, the frequency response of a micro-LED integrated with CMOS circuitry was measured and found to be up to 185MHz. Despite the reduction in bandwidth compared to the bare measurements using a high speed probe, a good compromise is achieved from the additional control available to select each pixel. It has been shown that modulating more than one pixel simultaneously can increase the data rate. As work continues in this area, the aim will be to further increase the data transmission rate by modulating more pixels on a single device to transmit multiple parallel data channels simultaneously.

  16. Growth and fabrication of deep ultraviolet light emitting diodes on silicon carbide substrates

    NASA Astrophysics Data System (ADS)

    Moe, Craig Gunar

    Interest in deep ultraviolet (< 280 nm) emitters has developed rapidly in recent years, with its use in applications such as water purification, solid state lighting, and biochemical detection now being explored. The aluminum nitride and aluminum gallium nitride material systems are ideal for low cost, highly efficient emitters at these wavelengths, in the same manner that the InGaN LED revolutionized light emitters in the blue, green, and near-ultraviolet wavelengths. While the work to date on such devices have made use of sapphire as a substrate for epitaxial growth, silicon carbide has significant advantages including ease of growth and manufacture, reproducibility, and the potential for fewer dislocations in the material. This work follows the development of AlN and high-composition AlGaN films on SiC to a sufficient quality for emitter applications. A comprehensive examination of the AlN nucleation and buffer layers led to dislocation densities in the low 109cm-2. An extensive study of the n- and p-type doping of AlxGa 1-xN (x > 0.5) was undertaken to develop highly conductive material. The internal quantum efficiency of the quantum well region was significantly improved through modified growth conditions and precursor selection, and a device fabrication process was developed to obtain low turn-on voltages below 5 V and reliable device performance for over 100 hours of use. Careful thermal management of the devices through novel mask designs and improvement in packaging allowed for significant advances in light extraction, resulting in high-power LED emission at 280 nm. Packaged dies exhibited powers as high as 52 muW at 20 mA and 0.24 mW at 100 mA. The greatest obstacle to high external quantum efficiency in these devices is the absorbing nature SiC substrate. This has been successfully mitigated through two different techniques. First, distributed Bragg reflectors consisting of AlGaN/AlN stacks have been developed, with reflectivities greater than 80% at 275

  17. Monolithic watt-level millimeter-wave diode-grid frequency tripler array

    NASA Technical Reports Server (NTRS)

    Hwu, R. J.; Luhmann, N. C., Jr.; Rutledge, D. B.; Hancock, B.; Lieneweg, U.

    1988-01-01

    In order to provide watt-level CW output power throughout the millimeter and submillimeter wave region, thousands of solid-state diodes have been monolithically integrated using a metal grid to produce a highly efficient frequency multiplier. Devices considered include GaAs Schottky diodes, thin MOS diodes, and GaAs Barrier-Intrinsic-N(+)diodes. The performance of the present compact low-cost device has been theoretically and experimentally validated.

  18. Wearable red–green–blue quantum dot light-emitting diode array using high-resolution intaglio transfer printing

    PubMed Central

    Choi, Moon Kee; Yang, Jiwoong; Kang, Kwanghun; Kim, Dong Chan; Choi, Changsoon; Park, Chaneui; Kim, Seok Joo; Chae, Sue In; Kim, Tae-Ho; Kim, Ji Hoon; Hyeon, Taeghwan; Kim, Dae-Hyeong

    2015-01-01

    Deformable full-colour light-emitting diodes with ultrafine pixels are essential for wearable electronics, which requires the conformal integration on curvilinear surface as well as retina-like high-definition displays. However, there are remaining challenges in terms of polychromatic configuration, electroluminescence efficiency and/or multidirectional deformability. Here we present ultra-thin, wearable colloidal quantum dot light-emitting diode arrays utilizing the intaglio transfer printing technique, which allows the alignment of red–green–blue pixels with high resolutions up to 2,460 pixels per inch. This technique is readily scalable and adaptable for low-voltage-driven pixelated white quantum dot light-emitting diodes and electronic tattoos, showing the best electroluminescence performance (14,000 cd m−2 at 7 V) among the wearable light-emitting diodes reported up to date. The device performance is stable on flat, curved and convoluted surfaces under mechanical deformations such as bending, crumpling and wrinkling. These deformable device arrays highlight new possibilities for integrating high-definition full-colour displays in wearable electronics. PMID:25971194

  19. Ultraviolet light-emitting diode irradiation-induced cell death in HL-60 human leukemia cells in vitro

    PubMed Central

    XIE, DONG; SUN, YAN; WANG, LINGZHEN; LI, XIAOLING; ZANG, CHUANNONG; ZHI, YUNLAI; SUN, LIRONG

    2016-01-01

    Ultraviolet (UV) radiation is considered to be a potent cell-damaging agent in various cell lineages; however, the effect of UV light-emitting diode (LED) irradiation on human cells remains unclear. The aim of the present study was to examine the effect of UV LED irradiation emitting at 280 nm on cultured HL-60 human leukemia cells, and to explore the underlying mechanisms. HL-60 cells were irradiated with UV LED (8, 15, 30 and 60 J/m2) and incubated for 2 h after irradiation. The rates of cell proliferation and apoptosis, the cell cycle profiles and the mRNA expression of B-cell lymphoma 2 (Bcl-2) were detected using cell counting kit-8, multicaspase assays, propidium iodide staining and reverse transcription-quantitative polymerase chain reaction, respectively. The results showed that UV LED irradiation (8–60 J/m2) inhibited the proliferation of HL-60 cells in a dose-dependent manner. UV LED at 8–30 J/m2 induced dose-dependent apoptosis and G0/G1 cell cycle arrest, and inhibited the expression of Bcl-2 mRNA, while UV LED at 60 J/m2 induced necrosis. In conclusion, 280 nm UV LED irradiation inhibits proliferation and induces apoptosis and necrosis in cultured HL-60 cells. In addition, the cell cycle arrest at the G0/G1 phase and the downregulation of Bcl-2 mRNA expression were shown to be involved in UV LED-induced apoptosis. PMID:26820261

  20. Application of GaN-based ultraviolet-C light emitting diodes--UV LEDs--for water disinfection.

    PubMed

    Würtele, M A; Kolbe, T; Lipsz, M; Külberg, A; Weyers, M; Kneissl, M; Jekel, M

    2011-01-01

    GaN-based ultraviolet-C (UV-C) light emitting diodes (LEDs) are of great interest for water disinfection. They offer significant advantages compared to conventional mercury lamps due to their compact form factor, low power requirements, high efficiency, non-toxicity, and overall robustness. However, despite the significant progress in the performance of semiconductor based UV LEDs that has been achieved in recent years, these devices still suffer from low emission power and relatively short lifetimes. Even the best UV LEDs exhibit external quantum efficiencies of only 1-2%. The objective of this study was to investigate the suitability of GaN-based UV LEDs for water disinfection. The investigation included the evaluation of the performance characteristics of UV LEDs at different operating conditions as well as the design of a UV LED module in view of the requirements for water treatment applications. Bioanalytical testing was conducted using Bacillus subtilis spores as test organism and UV LED modules with emission wavelengths of 269 nm and 282 nm. The results demonstrate the functionality of the developed UV LED disinfection modules. GaN-based UV LEDs effectively inactivated B. subtilis spores during static and flow-through tests applying varying water qualities. The 269 nm LEDs reached a higher level of inactivation than the 282 nm LEDs for the same applied fluence. The lower inactivation achieved by the 282 nm LEDs was compensated by their higher photon flux. First flow-through tests indicate a linear correlation between inactivation and fluence, demonstrating a well designed flow-through reactor. With improved light output and reduced costs, GaN-based UV LEDs can provide a promising alternative for decentralised and mobile water disinfection systems.

  1. High-efficiency integrated readout circuit for single photon avalanche diode arrays in fluorescence lifetime imaging.

    PubMed

    Acconcia, G; Cominelli, A; Rech, I; Ghioni, M

    2016-11-01

    In recent years, lifetime measurements by means of the Time Correlated Single Photon Counting (TCSPC) technique have led to a significant breakthrough in medical and biological fields. Unfortunately, the many advantages of TCSPC-based approaches come along with the major drawback of a relatively long acquisition time. The exploitation of multiple channels in parallel could in principle mitigate this issue, and at the same time it opens the way to a multi-parameter analysis of the optical signals, e.g., as a function of wavelength or spatial coordinates. The TCSPC multichannel solutions proposed so far, though, suffer from a tradeoff between number of channels and performance, and the overall measurement speed has not been increased according to the number of channels, thus reducing the advantages of having a multichannel system. In this paper, we present a novel readout architecture for bi-dimensional, high-density Single Photon Avalanche Diode (SPAD) arrays, specifically designed to maximize the throughput of the whole system and able to guarantee an efficient use of resources. The core of the system is a routing logic that can provide a dynamic connection between a large number of SPAD detectors and a much lower number of high-performance acquisition channels. A key feature of our smart router is its ability to guarantee high efficiency under any operating condition.

  2. Conjugated polymer-silicon nanowire array hybrid Schottky diode for solar cell application.

    PubMed

    Zhang, Fute; Song, Tao; Sun, Baoquan

    2012-05-17

    The hybrid Schottky diode based on silicon nanowire arrays (SiNWs) and poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS) has been fabricated for high performance solar cells. The length of SiNWs on a silicon substrate, which is prepared by metal-assisted chemical etching, can be tuned by adjusting the length of the etching time. In addition, the average distances between the adjacent silicon nanowires can be controlled by changing the immersing time in a saturated PCl(5) solution. The hybrid devices are made from the SiNWs with different wire lengths and various distances between adjacent wires by spin-casting PEDOT:PSS on the silicon substrates. It is found that the length and density play leading roles in the electric output characteristics. The device made from SiNWs with optimum morphology can achieve a power conversion efficiency of 7.3%, which is much improved in comparison with that of the planar one. The measurement of the transient photovoltage decay and the analysis of the current versus voltage curve indicate that the charge recombination process is a dominant factor on the device performance.

  3. Conjugated polymer-silicon nanowire array hybrid Schottky diode for solar cell application

    NASA Astrophysics Data System (ADS)

    Zhang, Fute; Song, Tao; Sun, Baoquan

    2012-05-01

    The hybrid Schottky diode based on silicon nanowire arrays (SiNWs) and poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS) has been fabricated for high performance solar cells. The length of SiNWs on a silicon substrate, which is prepared by metal-assisted chemical etching, can be tuned by adjusting the length of the etching time. In addition, the average distances between the adjacent silicon nanowires can be controlled by changing the immersing time in a saturated PCl5 solution. The hybrid devices are made from the SiNWs with different wire lengths and various distances between adjacent wires by spin-casting PEDOT:PSS on the silicon substrates. It is found that the length and density play leading roles in the electric output characteristics. The device made from SiNWs with optimum morphology can achieve a power conversion efficiency of 7.3%, which is much improved in comparison with that of the planar one. The measurement of the transient photovoltage decay and the analysis of the current versus voltage curve indicate that the charge recombination process is a dominant factor on the device performance.

  4. High-efficiency integrated readout circuit for single photon avalanche diode arrays in fluorescence lifetime imaging

    NASA Astrophysics Data System (ADS)

    Acconcia, G.; Cominelli, A.; Rech, I.; Ghioni, M.

    2016-11-01

    In recent years, lifetime measurements by means of the Time Correlated Single Photon Counting (TCSPC) technique have led to a significant breakthrough in medical and biological fields. Unfortunately, the many advantages of TCSPC-based approaches come along with the major drawback of a relatively long acquisition time. The exploitation of multiple channels in parallel could in principle mitigate this issue, and at the same time it opens the way to a multi-parameter analysis of the optical signals, e.g., as a function of wavelength or spatial coordinates. The TCSPC multichannel solutions proposed so far, though, suffer from a tradeoff between number of channels and performance, and the overall measurement speed has not been increased according to the number of channels, thus reducing the advantages of having a multichannel system. In this paper, we present a novel readout architecture for bi-dimensional, high-density Single Photon Avalanche Diode (SPAD) arrays, specifically designed to maximize the throughput of the whole system and able to guarantee an efficient use of resources. The core of the system is a routing logic that can provide a dynamic connection between a large number of SPAD detectors and a much lower number of high-performance acquisition channels. A key feature of our smart router is its ability to guarantee high efficiency under any operating condition.

  5. High Power 7-GHz Bandwidth External-Cavity Diode Laser Array and Its Use in Optically Pumping Singlet Delta Oxygen

    DTIC Science & Technology

    2006-10-11

    array,” Opt. Lett. 19, 1741 (1994). 2. Stuart MacCormack, Jack Feinberg, and M. H. Garrett , “Injection locking a laser-diode array with a phase...generate O2( 1∆) molecules, frequently called Singlet Delta Oxygen (SDO) molecules. High-power chemical oxygen-iodine lasers ( COIL ) use energy...45 A, thermal roll -over effect starts and output power drops due to high temperature (~30oC) of the DLA. The green data are the DLA’s free-running

  6. Micro-pixel array of organic light-emitting diodes applying imprinting technique with a polymer replica

    NASA Astrophysics Data System (ADS)

    Park, Tae Hyun; Kim, Young Min; Park, Young Wook; Choi, Jin Hwan; Jeong, Jin-Wook; Dong, Ki Young; Choi, Kyung Cheol; Ju, Byeong-Kwon

    2009-08-01

    Efficient micro-pixel array of small molecule organic light-emitting diodes (OLEDs) has been fabricated by an imprinting technique which uses a polymer replica. To confirm the effect of the oxygen plasma for removing the residual layer, the performance of two kinds of OLEDs with varying thicknesses of resin as the micro-pixel array, have been compared. The measured results of the OLEDs have shown comparable device performances that are significantly characterized depending on the residues on the substrate. The performance of enhanced device has achieved efficiencies of 3.6 cd/A and 1.9 lm/W at 20 mA/cm2.

  7. High reliability, high power arrays of 808 nm single mode diode lasers employing various quantum well structures

    NASA Astrophysics Data System (ADS)

    Qiu, B. C.; Kowalski, O.; McDougall, S. D.; Liu, X. F.; Marsh, J. H.

    2008-02-01

    Single mode laser diode arrays operating at 808 nm have been designed and fabricated using several different waveguide and quantum well combinations. In order to operate these devices at 200 mW per element a quantum well intermixing process has been used to render their facets non-absorbing and thus they do not suffer from mirror damage related failure. In this paper we demonstrate extremely high levels of reliability for GaAs and AlGaAs quantum well devices with arrays of 64 elements completing over 6000 hours continuous operation without any single laser element failure and a correspondingly low power degradation rate of <1% k/hr. In contrast we show extremely high power degradation rates for arrays using InGaAs and InAlGaAs 808 nm quantum wells laser arrays.

  8. Novel exposure system using light-emitting diodes and an optical fiber array for printing serial numbers and code marks.

    PubMed

    Iwasaki, J; Horiuchi, T

    2012-04-01

    Feasibility of a novel exposure system to print serial numbers and two-dimensional code marks was demonstrated. The new system used light-emitting diodes (LEDs) combined with an optical fiber matrix array as a light source. At first, as preparatory experiments, code mark patterns were printed using a prototype exposure system without using the optical fiber array but using the combination of arrayed LEDs with a central wavelength of 428 nm, spherical lenses, and rod lenses. Although the code mark patterns were successfully printed, it took too much exposure time. For this reason, bullet-type LEDs with a high power and a shorter wavelength of 405 nm were used and the optical fiber matrix array was adopted. Because the emitted light rays were efficiently taken into the fiber, and the resist sensitivity was improved, practically available short exposure time of less than 2 s was obtained.

  9. Near-Ultraviolet Light-Emitting Devices Using Vertical ZnO Nanorod Arrays

    NASA Astrophysics Data System (ADS)

    Jha, S.; Wang, C. D.; Luan, C. Y.; Liu, C. P.; Bin, H.; Kutsay, O.; Bello, I.; Zapien, J. A.; Zhang, W. J.; Lee, S. T.

    2012-05-01

    Reports on electroluminescence (EL) in solid-state, nanomaterial-based devices emitting in the lower wavelength range of the visible spectrum are limited, and the emission stability of these devices is rarely reported. We have fabricated light-emitting devices (LEDs) based on integration of n-ZnO nanorods and p-GaN films, which emit in the violet to near-ultraviolet (NUV) region. We also present data on the stability of EL in fabricated devices. Vertical arrays on ZnO nanorods, with estimated ZnO nanorod density ~108 cm-2, were grown on p-GaN films with typical length of ~4 μm and width of ~120 nm. The NUV LEDs show low turn-on voltage (~3.0 V), small reverse saturation current (~10 μA), and more than two orders of magnitude rectification ratio, all of which indicates a good-quality p- n junction at the p-GaN/ n-ZnO nanorod interface. The EL spectra of LEDs present an emission band centered at ~403 nm. Gaussian fitting of the EL peak revealed three emission peaks at 378 nm, 405 nm, and 431 nm with dominant emission in the NUV region. Significantly, the fabricated NUV LEDs present stable and repeatable EL characteristics, as revealed by bias-stress stability tests. The good electrical properties and stable EL performance make these nanostructure-based NUV LEDs potential candidates for mass production of next-generation lighting devices.

  10. Enhanced optical output of InGaN/GaN near-ultraviolet light-emitting diodes by localized surface plasmon of colloidal silver nanoparticles.

    PubMed

    Hong, Sang-Hyun; Kim, Jae-Joon; Kang, Jang-Won; Jung, Yen-Sook; Kim, Dong-Yu; Yim, Sang-Youp; Park, Seong-Ju

    2015-09-25

    We report on the characteristics of localized surface plasmon (LSP)-enhanced near-ultraviolet light-emitting diodes (NUV-LEDs) fabricated by using colloidal silver (Ag) nanoparticles (NPs). Colloidal Ag NPs were deposited on the 20 nm thick p-GaN spacer layer using a spray process. The optical output power of NUV-LEDs with colloidal Ag NPs was increased by 48.7% at 20 mA compared with NUV-LEDs without colloidal Ag NPs. The enhancement was attributed to increased internal quantum efficiency caused by the resonance coupling between excitons in the multiple quantum wells and the LSPs in the Ag NPs.

  11. Sub-milliwatt AlGaN nanowire tunnel junction deep ultraviolet light emitting diodes on silicon operating at 242 nm

    NASA Astrophysics Data System (ADS)

    Zhao, S.; Sadaf, S. M.; Vanka, S.; Wang, Y.; Rashid, R.; Mi, Z.

    2016-11-01

    We report AlGaN nanowire light emitting diodes (LEDs) operating in the ultraviolet-C band. The LED structures are grown by molecular beam epitaxy on Si substrate. It is found that with the use of the n+-GaN/Al/p+-AlGaN tunnel junction (TJ), the device resistance is reduced by one order of magnitude, and the light output power is increased by two orders of magnitude, compared to AlGaN nanowire LEDs without TJ. For unpackaged TJ ultraviolet LEDs emitting at 242 nm, a maximum output power of 0.37 mW is measured, with a peak external quantum efficiency up to 0.012%.

  12. Variable FOV optical illumination system with constant aspect ratio for 2-D array lasers diodes

    NASA Astrophysics Data System (ADS)

    Arasa, J.; de la Fuente, M. C.; Ibañez, C.

    2008-09-01

    In this contribution we present a compact system to create an illumination distribution with a constant aspect ratio 3:4 and FOV from 0.4 to 1 degree. Besides, the system must delivery 40 W from 170 individual laser diodes placed in a regular 2-D array distribution of 10 x 20 mm. The main problem that must be solved is the high asymmetry of the individual sources; emission divergence's ratio 3:73 (0.3 vs. 7.4 degree) combined with the flux holes due to the laser's heat drain. In one axis (divergence of 0.3º) the best design strategy approach is a Galileo telescope but in the other axis a collimator configuration is the best solution. To manage both solutions at the same time is the aim of this contribution. Unfortunately for the Galileo strategy, source dimensions are too large so aspheric surfaces are needed, and the collimator configuration requires an EFL that must change from 573 to 1432 mm. The presented solution uses a set of three fixed anamorphic lenses, two of them pure cylinders, combined with a wheel of anamorphic lenses that have the function to change the FOV of the system. The most important contribution of the design is to obtain a constant final ratio 3:4 from an initial ratio of 3:73 with no losses of energy. The proposed solution produces an illumination pattern with peaks and valleys lower than 40%. This pattern distribution might be unacceptable for a standard illumination solution. However, the actual FOV is used to illuminate far away targets thus air turbulence is enough to homogenize the distribution on the target.

  13. [Saliva cotinine determination using high-performance liquid chromatography with diode - array detection].

    PubMed

    Kulza, Maksymilian; Woźniak, Anna; Seńczuk-Przybyłowska, Monika; Czarnywojtek, Agata; Kurhańska-Flisykowska, Anna; Florek, Ewa

    2012-01-01

    The use of tobacco is a very serious threat to public health. Reducing the proportion of smokers easily leads to improved health of the general population. Smoking is a proven risk factor for respiratory disease, cardiovascular disease and cancer and complications during pregnancy. To verify the level of exposure to tobacco smoke in most patients used a simple test markers of exposure. The most commonly used marker in the evaluation of exposure to tobacco products is cotinine, which is a major metabolite of nicotine contained in tobacco smoke. Biological material most commonly used in this type of study is blood, urine and saliva. In the present study Sarstedt Salivette tubes were used to samples collection. In order to determine the concentration of cotinine in saliva samples analyzed with high performance liquid chromatography with diode array detection after extraction of cotinine from saliva by solid phase extraction. The method was linear of 10 to 400 ng/ml. The limit of detection was the value of the signal-to-noise ratio S/N=3, it amounted to 6 ng/ml, the limit of quantification was 10 ng/ml. The intraday repeatability was 8% for lowconcentrations, for high concentrations - 3.7%. Reproducibility interdays for low concentrations was 2.4%, for high concentrations - 4.1%. We analyzed 18 samples of saliva derived from patients smoking volunteers from the Department of Conservative Dentistry and Periodontology, University of Medical Sciences. University of Medical Sciences and the Chair and Department of Endocrinology, Metabolism and Internal Medicine, University of Medical Sciences. University of Medical Sciences. Mean concentrations of cotinine in patients was 240.9 ng/ml of saliva. In this study we demonstrated the usefulness of the saliva cotinine determination method in the assessment of patient exposure to tobacco smoke.

  14. Performance of a cylindrical diode array for use in a 1.5 T MR-linac

    NASA Astrophysics Data System (ADS)

    Houweling, A. C.; de Vries, J. H. W.; Wolthaus, J.; Woodings, S.; Kok, J. G. M.; van Asselen, B.; Smit, K.; Bel, A.; Lagendijk, J. J. W.; Raaymakers, B. W.

    2016-02-01

    At the UMC Utrecht, a linear accelerator with integrated magnetic resonance imaging (MRI) has been developed, the MR-linac. Patient-specific quality assurance (QA) of treatment plans for MRI-based image guided radiotherapy requires QA equipment compatible with this 1.5 T magnetic field. The purpose of this study was to examine the performance characteristics of the ArcCHECK-MR in a transverse 1.5 T magnetic field. To this end, the short-term reproducibility, dose linearity, dose rate dependence, field size dependence, dose per pulse dependence and inter-diode dose response variation of the ArcCHECK-MR diode array were evaluated on a conventional linac and on the MR-linac. The ArcCHECK-MR diode array performed well for all tests on both linacs, no significant differences in performance characteristics were observed. Differences in the maximum dose deviations between both linacs were less than 1.5%. Therefore, we conclude that the ArcCHECK-MR can be used in a transverse 1.5 T magnetic field.

  15. Characterization of a novel two dimensional diode array the ''magic plate'' as a radiation detector for radiation therapy treatment

    SciTech Connect

    Wong, J. H. D.; Fuduli, I.; Carolan, M.; Petasecca, M.; Lerch, M. L. F.; Perevertaylo, V. L.; Metcalfe, P.; Rosenfeld, A. B.

    2012-05-15

    Purpose: Intensity modulated radiation therapy (IMRT) utilizes the technology of multileaf collimators to deliver highly modulated and complex radiation treatment. Dosimetric verification of the IMRT treatment requires the verification of the delivered dose distribution. Two dimensional ion chamber or diode arrays are gaining popularity as a dosimeter of choice due to their real time feedback compared to film dosimetry. This paper describes the characterization of a novel 2D diode array, which has been named the ''magic plate'' (MP). It was designed to function as a 2D transmission detector as well as a planar detector for dose distribution measurements in a solid water phantom for the dosimetric verification of IMRT treatment delivery. Methods: The prototype MP is an 11 x 11 detector array based on thin (50 {mu}m) epitaxial diode technology mounted on a 0.6 mm thick Kapton substrate using a proprietary ''drop-in'' technology developed by the Centre for Medical Radiation Physics, University of Wollongong. A full characterization of the detector was performed, including radiation damage study, dose per pulse effect, percent depth dose comparison with CC13 ion chamber and build up characteristics with a parallel plane ion chamber measurements, dose linearity, energy response and angular response. Results: Postirradiated magic plate diodes showed a reproducibility of 2.1%. The MP dose per pulse response decreased at higher dose rates while at lower dose rates the MP appears to be dose rate independent. The depth dose measurement of the MP agrees with ion chamber depth dose measurements to within 0.7% while dose linearity was excellent. MP showed angular response dependency due to the anisotropy of the silicon diode with the maximum variation in angular response of 10.8% at gantry angle 180 deg. Angular dependence was within 3.5% for the gantry angles {+-} 75 deg. The field size dependence of the MP at isocenter agrees with ion chamber measurement to within 1.1%. In

  16. Analysis of surface and bulk effects in HgCdTe photodetector arrays by variable-area diode test structures

    NASA Astrophysics Data System (ADS)

    Deng, Yi; Lin, Chun; Hu, Xiaoning

    2009-07-01

    This study describes variable-area diode data analysis of surface and bulk effects of HgCdTe infrared photodiodes passivated with dual-layer CdTe/ZnS films. We attempt to present a general analytical relation between the zero-bias resistance-area product and the perimeter-to-area ratio of the diodes by variable-area diode array test structures. We have taken contributions into consideration from surface leakage between HgCdTe and passivant due to band bending, surface generation currents in the depletion region close to the HgCdTe-passivant interface, and the bulk currents. The model we use is based on the one put forward by Vishnu Gopal. The variable-area diode data analysis can be of great practical help in identifying the various possible mechanism contributing to the surface leakage currents. Through data analysis and curve fitting, we can also get some other useful parameters (like junction depth), which can be the reference to other experiment results. The experimental samples we used range from 20μm to 200μm in size and include both square and circular diode geometries. The conventional boron implantation was used to form the p-n junction and Au was used for the metal pads. The insulating layers of CdTe and ZnS were both electron-beam evaporated at a rate of 1.3 Å/sec. The fabricated diode test patterns were wire-bonded and packaged into a dewar system. I-V measurements were performed using a Keithley 4200 parameter analyzer. The data analysis and curve fitting are all dealt with by MATLAB. Through the results we can find that the surface leakage is nearly the same to the bulk current in diameter between 50~150μm, which indicate that surface leakage is still a dominating dark current in small dimension diode. The results also showed that diodes from 50 to 150μm in size have better performance than the larger or smaller ones and this can be explained by the limit of material imperfection and the limit of processing techniques.

  17. Instrumentation: Photodiode Array Detectors in UV-VIS Spectroscopy. Part II.

    ERIC Educational Resources Information Center

    Jones, Dianna G.

    1985-01-01

    A previous part (Analytical Chemistry; v57 n9 p1057A) discussed the theoretical aspects of diode ultraviolet-visual (UV-VIS) spectroscopy. This part describes the applications of diode arrays in analytical chemistry, also considering spectroelectrochemistry, high performance liquid chromatography (HPLC), HPLC data processing, stopped flow, and…

  18. Measurement and modeling of microlenses fabricated on single-photon avalanche diode arrays for fill factor recovery.

    PubMed

    Pavia, Juan Mata; Wolf, Martin; Charbon, Edoardo

    2014-02-24

    Single-photon avalanche diode (SPAD) imagers typically have a relatively low fill factor, i.e. a low proportion of the pixel's surface is light sensitive, due to in-pixel circuitry. We present a microlens array fabricated on a 128×128 single-photon avalanche diode (SPAD) imager to enhance its sensitivity. The benefits and limitations of these light concentrators are studied for low light imaging applications. We present a new simulation software that can be used to simulate microlenses' performance under different conditions and a new non-destructive contact-less method to estimate the height of the microlenses. Results of experiments and simulations are in good agreement, indicating that a gain >10 can be achieved for this particular sensor.

  19. Tunnel-injection quantum dot deep-ultraviolet light-emitting diodes with polarization-induced doping in III-nitride heterostructures

    SciTech Connect

    Verma, Jai Islam, S. M.; Protasenko, Vladimir; Kumar Kandaswamy, Prem; Xing, Huili; Jena, Debdeep

    2014-01-13

    Efficient semiconductor optical emitters in the deep-ultraviolet spectral window are encountering some of the most deep rooted problems of semiconductor physics. In III-Nitride heterostructures, obtaining short-wavelength photon emission requires the use of wide bandgap high Al composition AlGaN active regions. High conductivity electron (n-) and hole (p-) injection layers of even higher bandgaps are necessary for electrical carrier injection. This approach requires the activation of very deep dopants in very wide bandgap semiconductors, which is a difficult task. In this work, an approach is proposed and experimentally demonstrated to counter the challenges. The active region of the heterostructure light emitting diode uses ultrasmall epitaxially grown GaN quantum dots. Remarkably, the optical emission energy from GaN is pushed from 365 nm (3.4 eV, the bulk bandgap) to below 240 nm (>5.2 eV) because of extreme quantum confinement in the dots. This is possible because of the peculiar bandstructure and band alignments in the GaN/AlN system. This active region design crucially enables two further innovations for efficient carrier injection: Tunnel injection of carriers and polarization-induced p-type doping. The combination of these three advances results in major boosts in electroluminescence in deep-ultraviolet light emitting diodes and lays the groundwork for electrically pumped short-wavelength lasers.

  20. Excellent nonlinearity of a selection device based on anti-series connected Zener diodes for ultrahigh-density bipolar RRAM arrays

    NASA Astrophysics Data System (ADS)

    Li, Yingtao; Li, Rongrong; Fu, Liping; Gao, Xiaoping; Wang, Yang; Tao, Chunlan

    2015-10-01

    A crossbar array is usually used for the high-density application of a resistive random access memory (RRAM) device. However, the cross-talk interference limits the increase in the integration density. In this paper, anti-series connected Zener diodes as a selection device are proposed for bipolar RRAM arrays. Simulation results show that, by using the anti-series connected Zener diodes as a selection device, the readout margin is sufficiently improved compared to that obtained without a selection device or with anti-parallel connected diodes as the selection device. The maximum size of the crossbar arrays with anti-series connected Zener diodes as a selection device over 1 TB is estimated by theoretical simulation. In addition, the feasibility of using the anti-series connected Zener diodes as a selection device for bipolar RRAM is demonstrated experimentally. These results indicate that anti-series connected Zener diodes as a selection device opens up great opportunities to realize ultrahigh-density bipolar RRAM arrays.

  1. Nitride-based micron-scale hexagonal pyramids array vertical light emitting diodes by N-polar wet etching.

    PubMed

    Ma, Jun; Wang, Liancheng; Liu, Zhiqiang; Yuan, Guodong; Ji, Xiaoli; Ma, Ping; Wang, Junxi; Yi, Xiaoyan; Wang, Guohong; Li, Jinmin

    2013-02-11

    In this work, we reported the fabrication of nitride-based hexagonal pyramids array (HPA) vertical-injection light emitting diodes (V-LEDs) by N-polar wet etching. The performance of HPA V-LEDs devices was significantly improved with 30% higher internal quantum efficiency compared with conventional roughened broad area V-LEDs. The simulated extraction efficiency by finite difference time domain method was 20% higher than typical roughened V-LEDs. The reversed leakage current of HPA V-LEDs was reduced due to better crystal quality, which was confirmed by conductive atomic force microscopy measurement. Furthermore, the efficiency droop for HPA V-LEDs were substantially alleviated.

  2. A Comparative Analysis for Verification of IMRT and VMAT Treatment Plans using a 2-D and 3-D Diode Array

    NASA Astrophysics Data System (ADS)

    Dance, Michael J.

    With the added complexity of current radiation treatment dose delivery modalities such as IMRT (Intensity Modulated Radiation Therapy) and VMAT (Volumetric Modulated Arc Therapy), quality assurance (QA) of these plans become multifaceted and labor intensive. To simplify the patient specific quality assurance process, 2D or 3D diode arrays are used to measure the radiation fluence for IMRT and VMAT treatments which can then be quickly and easily compared against the planned dose distribution. Because the arrays that can be used for IMRT and VMAT patient-specific quality assurance are of different geometry (planar vs. cylindrical), the same IMRT or VMAT treatment plan measured by two different arrays could lead to different measured radiation fluences, regardless of the output and performance of linear accelerator. Thus, the purpose of this study is to compare patient specific QA results as measured by the MapCHECK 2 and ArcCHECK diode arrays for the same IMRT and VMAT treatment plans to see if one diode array consistently provides a closer comparison to reference data. Six prostate and three thoracic spine IMRT treatment plans as well as three prostate and three thoracic spine VMAT treatment plans were produced. Radiotherapy plans for this study were generated using the Pinnacle TPS v9.6 (Philips Radiation Oncology Systems, Fitchburg, WI) using 6 MV, 6 MV FFF, and 10 MV x-ray beams from a Varian TrueBeam linear accelerator (Varian Medical Systems, Palo Alto, CA) with a 120-millenium multi-leaf collimator (MLC). Each IMRT and VMAT therapy plan was measured on Sun Nuclear's MapCHECK 2 and ArcCHECK diode arrays. IMRT measured data was compared with planned dose distribution using Sun Nuclear's 3DVH quality assurance software program using gamma analysis and dose-volume histograms for target volumes and critical structures comparison. VMAT arc plans measured on the MapCHECK 2 and ArcCHECK were compared using beam-by-beam analysis with the gamma evaluation method with

  3. Cross-talk characterization of dense single-photon avalanche diode arrays in CMOS 150-nm technology

    NASA Astrophysics Data System (ADS)

    Xu, Hesong; Pancheri, Lucio; C. Braga, Leo H.; Betta, Gian-Franco Dalla; Stoppa, David

    2016-06-01

    Cross-talk characterization results of high-fill-factor single-photon avalanche diode (SPAD) arrays in CMOS 150-nm technology are reported and discussed. Three different SPAD structures were designed with two different sizes (15.6 and 25.6 μm pitch) and three guard ring widths (0.6, 1.1, and 1.6 μm). Each SPAD was implemented in an array, composed of 25 (5×5) devices, which can be separately activated. Measurement results show that the average cross-talk probability is well below 1% for the shallow-junction SPAD structure with 15.6 μm pitch and 39.9% fill factor, and 1.45% for the structure with 25.6 μm pitch and 60.6% fill factor. An increase of cross-talk probability with the excess bias voltage is observed.

  4. AlGaInN laser diode bar and array technology for high power and individually addressable applications

    NASA Astrophysics Data System (ADS)

    Najda, Stephen P.; Perlin, Piotr; Suski, Tadek; Marona, Lucja; Boćkowski, Mike; Leszczyński, Mike; Wisniewski, Przemek; Czernecki, Robert; Kucharski, Robert; Targowski, Grzegorz

    2015-05-01

    The AlGaInN material system allows for laser diodes to be fabricated over a very wide range of wavelengths from u.v., ~380nm, to the visible ~530nm, by tuning the indium content of the laser GaInN quantum well. Low defectivity and high uniformity GaN substrates allows arrays and bars of AlGaInN lasers with up to 20 emitters to be fabricated to obtain optical powers up to 4W at 395nm. AlGaInN laser bars are suitable for optical pumps and novel extended cavity systems for a wide range of applications. An alternative package configuration for AlGaInN laser arrays allows for each individual laser to be addressed individually allowing complex free-space and/or fibre optic system integration with a very small form-factor.

  5. Surface plasmon enhanced green light emitting diodes with silver nanorod arrays embedded in p-GaN

    NASA Astrophysics Data System (ADS)

    Huang, Yaping; Yun, Feng; Wang, Yue; Ding, Wen; Li, Yufeng; Wang, Hong; Zhang, Ye; Guo, Maofeng; Su, Xilin; Liu, Shuo; Hou, Xun

    2014-08-01

    We demonstrated surface-plasmon (SP) enhanced green light-emitting diodes (LEDs). Three types of Ag nanorod arrays with a minimum distance between the quantum well (QW) and Ag of 20, 40, and 55 nm respectively were fabricated on p-GaN layer. Photoluminescence measurements showed ˜175% emission enhancement for the 20 nm spacing while almost no enhancement for the 55 nm spacing. Simulation result showed that a localized surface plasmon resonance (LSPR) at a wavelength of ˜500 nm generated by Ag nanorod arrays induced InGaN/GaN QW and SP coupling. However, the electrical field of the LSPR generated by Ag nanorods only spread ˜40 nm in the vertical direction in GaN. This simulation result well explains the observation of SP-QW coupling emission enhancement for 20 nm spacing between Ag and QW, and the lack of enhancement for the 55 nm spacing samples.

  6. High-purity hydrogen generation by ultraviolet illumination with the membrane composed of titanium dioxide nanotube array and Pd layer

    NASA Astrophysics Data System (ADS)

    Hattori, Masashi; Noda, Kei; Matsushige, Kazumi

    2011-09-01

    High-purity hydrogen generation was observed by using a membrane composed of a bilayer of an anodized titanium dioxide nanotube array (TNA) and a hydrogen permeable metal. This membrane was fabricated by transferring a TNA embedded in a titanium foil onto a sputtered 10-μm-thick palladium film. Alcohols are reformed photocatalytically and concurrently generated hydrogen is purified through the Pd layer. H2 with a purity of more than 99% was obtained from liquid alcohols under ultraviolet illumination onto the membrane. Thus, we demonstrated the integration of photocatalytic hydrogen production and purification within a single membrane.

  7. Vertically p-n-junctioned GaN nano-wire array diode fabricated on Si(111) using MOCVD.

    PubMed

    Park, Ji-Hyeon; Kim, Min-Hee; Kissinger, Suthan; Lee, Cheul-Ro

    2013-04-07

    We demonstrate the fabrication of n-GaN:Si/p-GaN:Mg nanowire arrays on (111) silicon substrate by metal organic chemical vapor deposition (MOCVD) method .The nanowires were grown by a newly developed two-step growth process. The diameter of as-grown nanowires ranges from 300-400 nm with a density of 6-7 × 10(7) cm(-2). The p- and n-type doping of the nanowires is achieved with Mg and Si dopant species. Structural characterization by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) indicates that the nanowires are relatively defect-free. The room-temperature photoluminescence emission with a strong peak at 370 nm indicates that the n-GaN:Si/p-GaN:Mg nanowire arrays have potential application in light-emitting nanodevices. The cathodoluminscence (CL) spectrum clearly shows a distinct optical transition of GaN nanodiodes. The nano-n-GaN:Si/p-GaN:Mg diodes were further completed using a sputter coating approach to deposit Au/Ni metal contacts. The polysilazane filler has been etched by a wet chemical etching process. The n-GaN:Si/p-GaN:Mg nanowire diode was fabricated for different Mg source flow rates. The current-voltage (I-V) measurements reveal excellent rectifying properties with an obvious turn-on voltage at 1.6 V for a Mg flow rate of 5 sccm (standard cubic centimeters per minute).

  8. AlGaInN laser diode bar and array technology for high-power and individual addressable applications

    NASA Astrophysics Data System (ADS)

    Najda, S. P.; Perlin, P.; Suski, T.; Marona, L.; Boćkowski, M.; Leszczyński, M.; Wisniewski, P.; Czernecki, R.; Kucharski, R.; Targowski, G.

    2016-04-01

    The AlGaInN material system allows for laser diodes to be fabricated over a very wide range of wavelengths from u.v., ~380nm, to the visible ~530nm, by tuning the indium content of the laser GaInN quantum well, giving rise to new and novel applications for medical, industrial, display and scientific purposes. Ridge waveguide laser diode structures are fabricated to achieve single mode operation with high optical powers of >100mW with high reliability. Low defectivity and highly uniform GaN substrates allow arrays and bars of nitride lasers to be fabricated. We demonstrate the operation of monolithic AlGaInN laser bars with up to 20 emitters giving optical powers up to 4W cw at ~395nm with a common contact configuration. These bars are suitable for optical pumps and novel extended cavity systems. An alternative package configuration for AlGaInN laser arrays allows for each individual laser to be individually addressable allowing complex free-space and/or fibre optic system integration within a very small form-factor.

  9. Technique for Radiometer and Antenna Array Calibration with a Radiated Noise Diode

    NASA Technical Reports Server (NTRS)

    Srinivasan, Karthik; Limaye, Ashutosh; Laymon, Charles; Meyer, Paul

    2009-01-01

    This paper presents a new technique to calibrate a microwave radiometer and antenna array system. This calibration technique uses a radiated noise source in addition to two calibration sources internal to the radiometer. The method accurately calibrates antenna arrays with embedded active devices (such as amplifiers) which are used extensively in active phased array antennas.

  10. Optimization on the luminous efficiency in AlGaN-based ultraviolet light-emitting diodes by amendment of a superlattice hole reservoir layer

    NASA Astrophysics Data System (ADS)

    Yang, Xian; Sun, Huiqing; Fan, Xuancong; Zhang, Zhuding; Sun, Jie; Yi, Xinyan; Guo, Zhiyou

    2017-01-01

    The application of a p-type superlattice hole reservoir layer in the traditional ultraviolet light-emitting diodes (UVLED) can obtain better Internal quantum efficiency (IQE) and output power, ease the problem about efficient carrier movement in high Al-content AlGaN material. Through computation and analysis by using the APSYS simulation software, the change of position of the hole reservoir layer can influence the luminous efficiency. The design of a superlattice hole reservoir layer between electron blocking layer (EBL) and p-type AlGaN layer can obviously reduce the hole potential height and increase the electron potential height, produce more hole injection and less electron leak, leading to higher carrier concentration, so as to realize the further increased for carrier recombination rate.

  11. Light interaction in sapphire/MgF2/Al triple-layer omnidirectional reflectors in AlGaN-based near ultraviolet light-emitting diodes

    PubMed Central

    Lee, Keon Hwa; Moon, Yong-Tae; Song, June-O; Kwak, Joon Seop

    2015-01-01

    This study examined systematically the mechanism of light interaction in the sapphire/MgF2/Al triple-layer omnidirectional reflectors (ODR) and its effects on the light output power in near ultraviolet light emitting diodes (NUV-LEDs) with the ODR. The light output power of NUV-LEDs with the triple-layer ODR structure increased with decreasing surface roughness of the sapphire backside in the ODR. Theoretical modeling of the roughened surface suggests that the dependence of the reflectance of the triple-layer ODR structure on the surface roughness can be attributed mainly to light absorption by the Al nano-structures and the trapping of scattered light in the MgF2 layer. Furthermore, the ray tracing simulation based upon the theoretical modeling showed good agreement with the measured reflectance of the ODR structure in diffuse mode. PMID:26010378

  12. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: AlGaN-Based Deep-Ultraviolet Light Emitting Diodes Fabricated on AlN/sapphire Template

    NASA Astrophysics Data System (ADS)

    Sang, Li-Wen; Qin, Zhi-Xin; Fang, Hao; Zhang, Yan-Zhao; Li, Tao; Xu, Zheng-Yu; Yang, Zhi-Jian; Shen, Bo; Zhang, Guo-Yi; Li, Shu-Ping; Yang, Wei-Huang; Chen, Hang-Yang; Liu, Da-Yi; Kang, Jun-Yong

    2009-11-01

    We report on the growth and fabrication of deep ultraviolet (DUV) light emitting diodes (LEDs) on an AlN template which was grown on a pulsed atomic-layer epitaxial buffer layer. Threading dislocation densities in the AlN layer are greatly decreased with the introduction of this buffer layer. The crystalline quality of the AlGaN epilayer is further improved by using a low-temperature GaN interlayer between AlGaN and AlN. Electroluminescences of different DUV-LED devices at a wavelength of between 262 and 317 nm are demonstrated. To improve the hole concentration of p-type AlGaN, Mg-doping with trimethylindium assistance approach is performed. It is found that the serial resistance of DUV-LED decreases and the performance of DUV-LED such as EL properties is improved.

  13. Deep-ultraviolet light-emitting diodes with external quantum efficiency higher than 20% at 275 nm achieved by improving light-extraction efficiency

    NASA Astrophysics Data System (ADS)

    Takano, Takayoshi; Mino, Takuya; Sakai, Jun; Noguchi, Norimichi; Tsubaki, Kenji; Hirayama, Hideki

    2017-03-01

    Enhancing the light-extraction efficiency is the key issue for realizing highly efficient AlGaN-based ultraviolet light-emitting diodes (UV-LEDs). We introduced several features to improve the light extraction: a transparent AlGaN:Mg contact layer, a Rh mirror electrode, an AlN template on a patterned sapphire substrate, and encapsulation resin. The combination of the AlGaN:Mg contact layer and the Rh mirror electrode significantly improved the output power and the external quantum efficiency (EQE) of UV-LEDs. By introducing the aforementioned features, a maximum EQE of >20% at an emission wavelength of 275 nm and a 20-mA direct current was achieved.

  14. Band engineering for surface emission enhancement in Al-rich AlGaN-based deep-ultraviolet light emitting diodes

    NASA Astrophysics Data System (ADS)

    Lu, Huimin; Yu, Tongjun; Chen, Xinjuan; Wang, Jianping; Zhang, Guoyi

    2016-05-01

    The optical polarization properties of Al-rich AlGaN/AlN quantum wells (QWs) with different structure parameters were analyzed using the modified theoretical model based on the effective mass equation. It is demonstrated that the optical polarization properties of AlGaN-based QWs are determined by the valence subband structure, including the energy level order and the valence subband coupling. The results show that the TE-polarized emission is enhanced in Al-rich AlGaN/AlN QWs with smaller well width, a buffer layer inducing compressive stress, and a staggered well layer owing to the change in the valence subband structure. Hence, the enhancement of surface emission from deep-ultraviolet (DUV) AlGaN-based light-emitting diodes (LEDs) can be realized by adjusting the QW structure parameters to induce a valence subband change.

  15. Enhanced wall-plug efficiency in AlGaN-based deep-ultraviolet light-emitting diodes with uniform current spreading p-electrode structures

    NASA Astrophysics Data System (ADS)

    Hao, Guo-Dong; Taniguchi, Manabu; Tamari, Naoki; Inoue, Shin-ichiro

    2016-06-01

    The current crowding is an especially severe issue in AlGaN-based deep-ultraviolet (DUV) light-emitting diodes (LEDs) because of the low conductivity of the n-AlGaN cladding layer that has a high Al fraction. We theoretically investigated the improvement in internal quantum efficiency and total resistances in DUV-LEDs with an emission wavelength of 265 nm by a well-designed p-electrode geometry to produce uniform current spreading. As a result, the wall-plug efficiency was enhanced by a factor of 60% at an injection current of 350 mA in the designed uniform-current-spreading p-electrode LED when compared with an LED with a conventional cross-bar p-electrode pattern.

  16. Validation of an improved helical diode array and dose reconstruction software using TG-244 datasets and stringent dose comparison criteria.

    PubMed

    Ahmed, Saeed; Nelms, Benjamin; Kozelka, Jakub; Zhang, Geoffrey; Moros, Eduardo; Feygelman, Vladimir

    2016-11-08

    The original helical ArcCHECK (AC) diode array and associated software for 3D measurement-guided dose reconstruction were characterized and validated; however, recent design changes to the AC required that the subject be revisited. The most important AC change starting in 2014 was a significant reduction in the overresponse of diodes to scattered radiation outside of the direct beam, accom-plished by reducing the amount of high-Z materials adjacent to the diodes. This change improved the diode measurement accuracy, but in the process invalidated the dose reconstruction models that were assembled based on measured data acquired with the older version of the AC. A correction mechanism was intro-duced in the reconstruction software (3DVH) to accommodate this and potential future design changes without requiring updating model parameters. For each permutation of AC serial number and beam model, the user can define in 3DVH a single correction factor which will be used to compensate for the difference in the out-of-field response between the new and original AC designs. The exact value can be determined by minimizing the dose-difference with an ionization chamber or another independent dosimeter. A single value of 1.17, corresponding to the maximum measured out-of-field response difference between the new and old AC, provided satisfactory results for all studied energies (6X, 15X, and flatten-ing filter-free 10XFFF). A library of standard cases recommended by the AAPM TG-244 Report was used for reconstructed dose verification. The overall difference between reconstructed dose and an ion chamber in a water-equivalent phantom in the targets was 0.0% ± 1.4% (1 SD). The reconstructed dose on a homogeneous phantom was also compared to a biplanar diode dosimeter (Delta4) using gamma analysis with 2% (local dose-error normalization) / 2 mm / 10% cutoff criteria. The mean agreement rate was 96.7% ± 3.7%. For the plans common with the previous comparison, the mean agreement

  17. Validation of an improved helical diode array and dose reconstruction software using TG-244 datasets and stringent dose comparison criteria.

    PubMed

    Ahmed, Saeed; Nelms, Benjamin; Kozelka, Jakub; Zhang, Geoffrey; Moros, Eduardo; Feygelman, Vladimir

    2016-11-01

    The original helical ArcCHECK (AC) diode array and associated software for 3D measurement-guided dose reconstruction were characterized and validated; however, recent design changes to the AC required that the subject be revisited. The most important AC change starting in 2014 was a significant reduction in the overresponse of diodes to scattered radiation outside of the direct beam, accomplished by reducing the amount of high-Z materials adjacent to the diodes. This change improved the diode measurement accuracy, but in the process invalidated the dose reconstruction models that were assembled based on measured data acquired with the older version of the AC. A correction mechanism was introduced in the reconstruction software (3DVH) to accommodate this and potential future design changes without requiring updating model parameters. For each permutation of AC serial number and beam model, the user can define in 3DVH a single correction factor which will be used to compensate for the difference in the out-of-field response between the new and original AC designs. The exact value can be determined by minimizing the dose-difference with an ionization chamber or another independent dosimeter. A single value of 1.17, corresponding to the maximum measured out-of-field response difference between the new and old AC, provided satisfactory results for all studied energies (6X, 15X, and flattening filter-free 10XFFF). A library of standard cases recommended by the AAPM TG-244 Report was used for reconstructed dose verification. The overall difference between reconstructed dose and an ion chamber in a water-equivalent phantom in the targets was 0.0% ± 1.4% (1 SD). The reconstructed dose on a homogeneous phantom was also compared to a biplanar diode dosimeter (Delta4) using gamma analysis with 2% (local dose-error normalization)/2 mm/10% cutoff criteria. The mean agreement rate was 96.7% ± 3.7%. For the plans common with the previous comparison, the mean

  18. Wavelength-tunable and white-light emission from polymer-converted micropixellated InGaN ultraviolet light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Heliotis, G.; Gu, E.; Griffin, C.; Jeon, C. W.; Stavrinou, P. N.; Dawson, M. D.; Bradley, D. D. C.

    2006-07-01

    We report the use of light-emitting conjugated polymer materials to wavelength-convert the emission from a two-dimensional array of micropixellated InGaN light-emitting diodes (LEDs). We demonstrate hybrid organic/inorganic light-emitting devices that can operate across the entire visible spectrum, and we also fabricate white-emitting versions of these devices by employing single layers of carefully adjusted polymer blends in which cascade non-radiative energy transfer occurs between the constituent materials. Additional colours may be easily obtained by tuning the composition of the polymer blends. Our work demonstrates that the combination of conjugated polymers and UV micro-LED arrays provides an attractive approach to developing microscale wavelength-tunable light sources and may provide a route to low-cost full-colour microdisplays and other instrumentation devices.

  19. Calibration Transfer Between a Bench Scanning and a Submersible Diode Array Spectrophotometer for In Situ Wastewater Quality Monitoring in Sewer Systems.

    PubMed

    Brito, Rita S; Pinheiro, Helena M; Ferreira, Filipa; Matos, José S; Pinheiro, Alexandre; Lourenço, Nídia D

    2016-03-01

    Online monitoring programs based on spectroscopy have a high application potential for the detection of hazardous wastewater discharges in sewer systems. Wastewater hydraulics poses a challenge for in situ spectroscopy, especially when the system includes storm water connections leading to rapid changes in water depth, velocity, and in the water quality matrix. Thus, there is a need to optimize and fix the location of in situ instruments, limiting their availability for calibration. In this context, the development of calibration models on bench spectrophotometers to estimate wastewater quality parameters from spectra acquired with in situ instruments could be very useful. However, spectra contain information not only from the samples, but also from the spectrophotometer generally invalidating this approach. The use of calibration transfer methods is a promising solution to this problem. In this study, calibration models were developed using interval partial least squares (iPLS), for the estimation of total suspended solids (TSS) and chemical oxygen demand (COD) in sewage from Ultraviolet-visible spectra acquired in a bench scanning spectrophotometer. The feasibility of calibration transfer to a submersible, diode array equipment, to be subsequently operated in situ, was assessed using three procedures: slope and bias correction (SBC); single wavelength standardization (SWS) on mean spectra; and local centering (LC). The results showed that SBC was the most adequate for the available data, adding insignificant error to the base model estimates. Single wavelength standardization was a close second best, potentially more robust, and independent of the base iPLS model. Local centering was shown to be inadequate for the samples and instruments used.

  20. Use of a priori spectral information in the measurement of x-ray flux with filtered diode arrays.

    PubMed

    Marrs, R E; Widmann, K; Brown, G V; Heeter, R F; MacLaren, S A; May, M J; Moore, A S; Schneider, M B

    2015-10-01

    Filtered x-ray diode (XRD) arrays are often used to measure x-ray spectra vs. time from spectrally continuous x-ray sources such as hohlraums. A priori models of the incident x-ray spectrum enable a more accurate unfolding of the x-ray flux as compared to the standard technique of modifying a thermal Planckian with spectral peaks or dips at the response energy of each filtered XRD channel. A model x-ray spectrum consisting of a thermal Planckian, a Gaussian at higher energy, and (in some cases) a high energy background provides an excellent fit to XRD-array measurements of x-ray emission from laser heated hohlraums. If high-resolution measurements of part of the x-ray emission spectrum are available, that information can be included in the a priori model. In cases where the x-ray emission spectrum is not Planckian, candidate x-ray spectra can be allowed or excluded by fitting them to measured XRD voltages. Examples are presented from the filtered XRD arrays, named Dante, at the National Ignition Facility and the Laboratory for Laser Energetics.

  1. Use of a priori spectral information in the measurement of x-ray flux with filtered diode arrays

    NASA Astrophysics Data System (ADS)

    Marrs, R. E.; Widmann, K.; Brown, G. V.; Heeter, R. F.; MacLaren, S. A.; May, M. J.; Moore, A. S.; Schneider, M. B.

    2015-10-01

    Filtered x-ray diode (XRD) arrays are often used to measure x-ray spectra vs. time from spectrally continuous x-ray sources such as hohlraums. A priori models of the incident x-ray spectrum enable a more accurate unfolding of the x-ray flux as compared to the standard technique of modifying a thermal Planckian with spectral peaks or dips at the response energy of each filtered XRD channel. A model x-ray spectrum consisting of a thermal Planckian, a Gaussian at higher energy, and (in some cases) a high energy background provides an excellent fit to XRD-array measurements of x-ray emission from laser heated hohlraums. If high-resolution measurements of part of the x-ray emission spectrum are available, that information can be included in the a priori model. In cases where the x-ray emission spectrum is not Planckian, candidate x-ray spectra can be allowed or excluded by fitting them to measured XRD voltages. Examples are presented from the filtered XRD arrays, named Dante, at the National Ignition Facility and the Laboratory for Laser Energetics.

  2. Triggering GaAs lock-on switches with laser diode arrays

    NASA Astrophysics Data System (ADS)

    Loubriel, G. M.; Helgeson, W. D.; McLaughlin, D. L.; Omalley, M. W.; Zutavern, F. J.; Rosen, A.; Stabile, P. J.

    Many of the applications that require the unique capabilities of Photoconductive Semiconductor Switches (PCSS) demand a compact package. We have been able to demonstrate that GaAs switches operated in the high gain mode called lock-on meet the required electrical switching parameters of several such applications using small switch sizes. The only light source that has enough power to trigger a PCSS and is compatible with a small package is a laser diode. This paper will describe the progress that leads to the triggering of high power PCSS switches with laser diodes. Our goal is to switch up to 5 kA in a single shot mode and up to 100 MW repetitively at up to 10 kHz. These goals are feasible since the switches can be used in parallel or in series. Low light level triggering became possible after the discovery of a high electric field, high gain switching mode in GaAs (and later in InP). At electric fields below 3 kV/cm GaAs switches are activated by creation of, at most, only one conduction electron-valence hole pair per photon absorbed in the sample. This linear mode demands high laser power and, after the light is extinguished, the carriers live for only a few nanoseconds. At higher electric fields GaAs behaves as a light activated Zener diode. The laser light generates carriers as in the linear mode and the field induces gain such that the amount of light required to trigger the switch is reduced by a factor of up to 500. The gain continues until the field across the sample drops to a material dependent lock-on field. At this point the switch will carry as much current as, and for as long as, the circuit can maintain the lock-on field. The gain in the switch allows for the use of laser diodes.

  3. Triggering GaAs lock-on switches with laser diode arrays

    SciTech Connect

    Loubriel, G.M.; Helgeson, W.D.; McLaughlin, D.L.; O'Malley, M.W.; Zutavern, F.J. ); Rosen, A.; Stabile, P.J. )

    1990-01-01

    Many of the applications that require the unique capabilities of Photoconductive Semiconductor Switches (PCSS) demand a compact package. We have been able to demonstrate that GaAs switches operated in the high gain mode called lock-on'' meet the required electrical switching parameters of several such applications using small switch sizes. The only light source that has enough power to trigger a PCSS and is compatible with a small package is a laser diode. This paper will describe the progress that leads to the triggering of high power PCSS switches with laser diodes. Our goal is to switch up to 5 kA in a single shot mode and up to 100 MW repetitively at up to 10 kHz. These goals are feasible since the switches can be used in parallel or in series. Low light level triggering became possible after the discovery of a high electric field, high gain switching mode in GaAs (and later in InP). At electric fields below 3 kV/cm GaAs switches are activated by creation of, at most, only one conduction electron- valence hole pair per photon absorbed in the sample. This linear mode demands high laser power and, after the light is extinguished, the carriers live for only a few nanoseconds. At higher electric fields GaAs behaves as a light activated Zener diode. The laser light generates carriers as in the linear mode and the field induces gain such that the amount of light required to trigger the switch is reduced by a factor of up to 500. The gain continues until the field across the sample drops to a material dependent lock-on field. At this point the switch will carry as much current as, and for as long as, the circuit can maintain the lock-on field. The gain in the switch allows for the use of laser diodes. 8 refs., 11 figs.

  4. Soft lithography microlens fabrication and array for enhanced light extraction from organic light emitting diodes (OLEDs)

    DOEpatents

    Leung, Wai Y.; Park, Joong-Mok; Gan, Zhengqing; Constant, Kristen P.; Shinar, Joseph; Shinar, Ruth; ho, Kai-Ming

    2014-06-03

    Provided are microlens arrays for use on the substrate of OLEDs to extract more light that is trapped in waveguided modes inside the devices and methods of manufacturing same. Light extraction with microlens arrays is not limited to the light emitting area, but is also efficient in extracting light from the whole microlens patterned area where waveguiding occurs. Large microlens array, compared to the size of the light emitting area, extract more light and result in over 100% enhancement. Such a microlens array is not limited to (O)LEDs of specific emission, configuration, pixel size, or pixel shape. It is suitable for all colors, including white, for microcavity OLEDs, and OLEDs fabricated directly on the (modified) microlens array.

  5. Controlled fundamental supermode operation of phase-locked arrays of gain-guided diode lasers

    NASA Technical Reports Server (NTRS)

    Kapon, E.; Margalit, S.; Yariv, A.; Katz, J.

    1984-01-01

    Uniform semiconductor laser arrays tend to oscillate in a superposition of their supermodes, thus leading to large beam divergence and spectral spread. Discrimination among the supermodes in phase-locked arrays is discussed theoretically. It is shown that supermode discrimination in gain-guided arrays, in favor of the fundamental supermode, is made possible by the near-field interference patterns which result from the complex optical fields of the gain-guided lasers. A fundamental supermode operation is demonstrated, for the first time, in GaAlAs/GaAs gain-guided laser arrays. This is achieved by control of the current (gain) profile across the array by means of individual laser contacts.

  6. Coherent beam combining of high power broad-area laser diode array with near diffraction limited beam quality and high power conversion efficiency.

    PubMed

    Liu, B; Braiman, Y

    2013-12-16

    We explored a path of achieving high quality phase-locking of broad-area laser diode (BALD) array that operates at high electrical to optical power conversion efficiency (PCE). We found that (a) improving single transverse mode control for each individual BALD, (b) employing global Talbot optical coupling among diodes, and (c) enhancing strength of optical coupling among diodes are key factors in achieving high quality phase-locking of high power BALD array. Subsequently, we redesigned and improved a V-shaped external Talbot cavity and employed low reflectivity anti-reflection (AR) coated, low-"smile" BALD array to meet these three important requirements. We demonstrated near-diffraction limit far-field coherent pattern with 19% PCE and 95% visibility. The far-field angle (full-width at half-maximum (FWHM)) of center lobe was measured as 1.5 diffraction angular limited with visibility of 99% for 5A injection current and 1.6 diffraction angular limited with visibility of 95% for 14A injection current. Power scaling of diode array is discussed.

  7. DETERMINATION OF CARBENDAZIM IN WATER BY HIGH-PERFORMANCE IMMUNOAFFINITY CHROMATOGRAPHY ON-LINE WITH HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY WITH DIODE-ARRAY OR MASS SPECTROMETRIC DETECTION

    EPA Science Inventory

    An automated method for the determination of carbendazim in water that combines high-performance immunoaffinity chromatography (HPIAC), high-performance liquid chromatography (HPLC) in the reversed-phase mode, and detection by either UV-Vis diode array detector (DAD) spectroscopy...

  8. Breakthroughs in laser bar component packaging enable a new generation of applications for self-cooled laser diode arrays

    NASA Astrophysics Data System (ADS)

    Behringer, M.; Koenig, H.; Schmitt, A.; Nagappan, S.; Kojima, R.

    2005-09-01

    Laser Diode Arrays continue to gain momentum as versatile, cost effective, reliable solution for a wide variety of existing and emerging illumination and pumping applications. In order to meet these growing demands, designers find themselves faced with three challenges: reducing system size, improving user serviceability, and managing cost. We developed a compact laser package platform that offers high output power, good reliability, and different beam collimation options. Both active cooling and passive cooling is possible with this new packaging concept. It has the footprint of the TO263 package and is based on packaging concepts that were developed for high power semiconductor devices and high volume opto semiconductor products like Light Emitting Diodes. High efficiency and high power laser bars are critical to various pumping and material processing applications. Wavelength multiplexing is an option to increase output power from laser systems. Typical wavelengths used are 808nm, 940nm and 980nm. We discuss the results of wavelength multiplexing of 880nm high power lasers.

  9. Measurements of NO and OH Concentrations in Vitiated Air Using Diode Laser-Based Ultraviolet Absorption Sensors (Postprint)

    DTIC Science & Technology

    2006-12-01

    ITIATION has long been used to simulate high-Mach number flight conditions for ground tests of supersonic propulsion systems . In the vitiation process...been measured in a hypersonic wind tunnel using a cryogenically -cooled lead-salt diode laser.12 However, these previous NO measurements were severely...Wright-Patterson AFB is used to study supersonic fuel injection, flameholding, ignition, and inlet-combustor isolation in scramjet propulsion systems .17

  10. Fingerprint analysis and simultaneous determination of phenolic compounds in extracts of Curculiginis Rhizoma by HPLC-diode array detector.

    PubMed

    Bian, Qingya; Yang, Hui; Chan, Chi-On; Jin, Dengping; Mok, Daniel Kam-Wah; Chen, Sibao

    2013-01-01

    Curculiginis Rhizoma (Curculigo orchioides GAERTN.) is a well-known Chinese herbal medicine, as well as an important Rasayana drug in India. Current criteria of quality control on this herb are to quantitatively analyze single compound curculigoside, which fail to comprehensively evaluate quality of this herb. In this paper, a simple and reliable HPLC coupled with diode array detector (DAD) method was developed to evaluate the quality of Curculiginis Rhizoma through establishing chromatographic fingerprint and simultaneously quantitating four phenolic compounds, orcinol glucoside, orcinol, 2,6-dimethoxybenzoic acid and curculigoside. The fingerprint displayed eleven common peaks, and the similarity index of different samples was in a range of 0.890-0.977. Validation of the method was acceptable, with 96.03-102.82% accuracy in recovery test and inter and intra-day precisions were less than 2%. This developed method by having a combination of chromatographic fingerprint and quantitation analysis could be applied to the quality control of Curculiginis Rhizoma.

  11. Trace analysis of tiamulin in honey by liquid chromatography-diode array-electrospray ionization mass spectrometry detection.

    PubMed

    Nozal, M J; Bernal, J L; Martín, M T; Jiménez, J J; Bernal, J; Higes, M

    2006-05-26

    A liquid chromatography with diode array or electrospray ionisation mass spectrometry detection (LC-DAD-ESI-MS) method for the determination of tiamulin residues in honey is presented. The procedure employs a solid-phase extraction (SPE) on polymeric cartridges for the isolation of tiamulin from honey samples diluted in aqueous solution of tartaric acid. Chromatographic separation of the tiamulin is performed, in isocratic mode, on a C18 column using methanol and ammonium carbonate 0.1% in water, in proportion (30:70, v/v). Average analyte recoveries were from 88 to 106% in replica sets of fortified honey samples. The LC-ESI-MS method detection limits differ from 0.5 microg kg(-1) for clear honeys to 1.2 microg kg(-1) for dark honeys. The developed method has been applied to the analysis of tiamulin residues in multifloral honey samples collected from veterinary treated beehives.

  12. A Low-cost, Off-the-Shelf Ready Field Programmable Gate Array diode Laser Controller With adjustable parameters

    NASA Astrophysics Data System (ADS)

    Yang, Ge; Barry, John. F.; Shuman, Edward; Demille, David

    2010-03-01

    We have constructed a field programmable gate array (FPGA) based lock-in amplifier/PID servo controller for use in laser frequency locking and other applications. Our system is constructed from a commercial FPGA evaluation board with total cost less than 400 and no additional electronic component is required. FPGA technology allows us to implement parallel real-time signal processing with great flexibility. Internal parameters such as the modulation frequency, phase delay, gains and filter time constants, etc. can be changed on the fly within a very wide dynamic range through an iPod-like interface. This system was used to lock a tunable diode laser to an external Fabry Perot cavity with piezo and current feedback. A loop bandwidth of 200 kHz was achieved, limited only by the slow ADCs available on the FPGA board. Further improvements in both hardware and software seem possible, and will be discussed.

  13. Solid state active/passive night vision imager using continuous-wave laser diodes and silicon focal plane arrays

    NASA Astrophysics Data System (ADS)

    Vollmerhausen, Richard H.

    2013-04-01

    Passive imaging offers covertness and low power, while active imaging provides longer range target acquisition without the need for natural or external illumination. This paper describes a focal plane array (FPA) concept that has the low noise needed for state-of-the-art passive imaging and the high-speed gating needed for active imaging. The FPA is used with highly efficient but low-peak-power laser diodes to create a night vision imager that has the size, weight, and power attributes suitable for man-portable applications. Video output is provided in both the active and passive modes. In addition, the active mode is Class 1 eye safe and is not visible to the naked eye or to night vision goggles.

  14. Fabrication, characterization and applications of flexible vertical InGaN micro-light emitting diode arrays.

    PubMed

    Tian, Pengfei; McKendry, Jonathan J D; Gu, Erdan; Chen, Zhizhong; Sun, Yongjian; Zhang, Guoyi; Dawson, Martin D; Liu, Ran

    2016-01-11

    Flexible vertical InGaN micro-light emitting diode (micro-LED) arrays have been fabricated and characterized for potential applications in flexible micro-displays and visible light communication. The LED epitaxial layers were transferred from initial sapphire substrates to flexible AuSn substrates by metal bonding and laser lift off techniques. The current versus voltage characteristics of flexible micro-LEDs degraded after bending the devices, but the electroluminescence spectra show little shift even under a very small bending radius 3 mm. The high thermal conductivity of flexible metal substrates enables high thermal saturation current density and high light output power of the flexible micro-LEDs, benefiting the potential applications in flexible high-brightness micro-displays and high-speed visible light communication. We have achieved ~40 MHz modulation bandwidth and 120 Mbit/s data transmission speed for a typical flexible micro-LED.

  15. Floral classification of honey using liquid chromatography-diode array detection-tandem mass spectrometry and chemometric analysis.

    PubMed

    Zhou, Jinhui; Yao, Lihu; Li, Yi; Chen, Lanzhen; Wu, Liming; Zhao, Jing

    2014-02-15

    A high performance liquid chromatography-diode array detection-tandem mass spectrometry (HPLC-DAD-MS/MS) method for the floral origin traceability of chaste honey and rape honey samples was firstly presented in this study. Kaempferol, morin and ferulic acid were used as floral markers to distinguish chaste honey from rape honey. Chromatographic fingerprinting at 270 nm and 360 nm could be used to characterise chaste honey and rape honey according to the analytical profiles. Principal component analysis (PCA), partial least squares (PLS), partial least squares-discrimination analysis (PLS-DA) and soft independent modeling of class analogy (SIMCA) were applied to classify the honey samples according to their floral origins. The results showed that chaste honey and rape honey could be successfully classified by their floral sources with the analytical methods developed through this study and could be considered encouraging and promising for the honey traceability from unifloral or multifloral nectariferous sources.

  16. Miniaturized time-resolved Raman spectrometer for planetary science based on a fast single photon avalanche diode detector array.

    PubMed

    Blacksberg, Jordana; Alerstam, Erik; Maruyama, Yuki; Cochrane, Corey J; Rossman, George R

    2016-02-01

    We present recent developments in time-resolved Raman spectroscopy instrumentation and measurement techniques for in situ planetary surface exploration, leading to improved performance and identification of minerals and organics. The time-resolved Raman spectrometer uses a 532 nm pulsed microchip laser source synchronized with a single photon avalanche diode array to achieve sub-nanosecond time resolution. This instrument can detect Raman spectral signatures from a wide variety of minerals and organics relevant to planetary science while eliminating pervasive background interference caused by fluorescence. We present an overview of the instrument design and operation and demonstrate high signal-to-noise ratio Raman spectra for several relevant samples of sulfates, clays, and polycyclic aromatic hydrocarbons. Finally, we present an instrument design suitable for operation on a rover or lander and discuss future directions that promise great advancement in capability.

  17. One joule output from a diode-array-pumped Nd:YAG laser with side-pumped rod geometry

    NASA Technical Reports Server (NTRS)

    Kasinski, Jeffrey J.; Hughes, Will; Dibiase, Don; Bournes, Patrick; Burnham, Ralph

    1992-01-01

    Output of 1.25 J per pulse (1.064 micron) with an absolute optical efficiency of 28 percent and corresponding electrical efficiency of 10 percent was demonstrated in a diode-array-pumped Nd:YAG laser using a side-pumped rod geometry in a master-oscillator/power-amplifier configuration. In Q-switched operation, an output of 0.75 J in a 17-ns pulse was obtained. The fundamental laser output was frequency doubled in KTP with 60 percent conversion efficiency to obtain 0.45 J in a 16-ns pulse at 532 nm. The output beam had high spatial quality with pointing stability better than 40 microrad and a shot-to-shot pulse energy fluctuation of less than +/-3 percent.

  18. High-efficiency, high-output-power antiguide laser diode arrays

    NASA Technical Reports Server (NTRS)

    Mehuys, D.; Major, J. S., Jr.; Welch, D.; Scifres, D. R.

    1992-01-01

    Antiguide laser arrays have been fabricated and operated up to peak pulsed powers of 7.7 W in a beam with a full-width at half-maximum in the main lobe of 0.7 deg. Up to 0.7 W of continuous wave power is emitted into a radiation pattern 2.5 times the diffraction limit. By varying the temperature of the array to vary the operating wavelength of the device, the threshold gain condition of the array modes is altered, allowing thermal tuning of the far field of the device.

  19. Technique for Radiometer and Antenna Array Calibration with Two Antenna Noise Diodes

    NASA Technical Reports Server (NTRS)

    Srinivasan, Karthik; Limaye, Ashutosh; Laymon, Charles; Meyer, Paul

    2011-01-01

    This paper presents a new technique to calibrate a microwave radiometer and phased array antenna system. This calibration technique uses a radiated noise source in addition to an injected noise sources for calibration. The plane of reference for this calibration technique is the face of the antenna and therefore can effectively calibration the gain fluctuations in the active phased array antennas. This paper gives the mathematical formulation for the technique and discusses the improvements brought by the method over the existing calibration techniques.

  20. SU-F-BRE-06: Evaluation of Patient CT Dose Reconstruction From 3D Diode Array Measurements Using Anthropomorphic Phantoms

    SciTech Connect

    Huang, M; Benhabib, S; Cardan, R; Brezovich, I; Popple, R; Faught, A; Followill, D

    2014-06-15

    Purpose: To compare 3D reconstructed dose of IMRT plans from 3D diode array measurements with measurements in anthropomorphic phantoms. Methods: Six IMRT plans were created for the IROC Houston (RPC) head and neck (H and N) and lung phantoms following IROC Houston planning protocols. The plans included flattened and unflattened beam energies ranging from 6 MV to 15 MV and both static and dynamic MLC tecH and Niques. Each plan was delivered three times to the respective anthropomorphic phantom, each of which contained thermoluminescent dosimeters (TLDs) and radiochromic films (RCFs). The plans were also delivered to a Delta4 diode array (Scandidos, Uppsala, Sweden). Irradiations were done using a TrueBeam STx (Varian Medical Systems, Palo Alto, CA). The dose in the patient was calculated by the Delta4 software, which used the diode measurements to estimate incident energy fluence and a kernel-based pencil beam algorithm to calculate dose. The 3D dose results were compared with the TLD and RCF measurements. Results: In the lung, the average difference between TLDs and Delta4 calculations was 5% (range 2%–7%). For the H and N, the average differences were 2.4% (range 0%–4.5%) and 1.1% (range 0%–2%) for the high- and low-dose targets, respectively, and 12% (range 10%-13%) for the organ-at-risk simulating the spinal cord. For the RCF and criteria of 7%/4mm, 5%/3mm, and 3%/3mm, the average gamma-index pass rates were 95.4%, 85.7%, and 76.1%, respectively for the H and N and 76.2%, 57.8%, and 49.5% for the lung. The pass-rate in the lung decreased with increasing beam energy, as expected for a pencil beam algorithm. Conclusion: The H and N phantom dose reconstruction met the IROC Houston acceptance criteria for clinical trials; however, the lung phantom dose did not, most likely due to the inaccuracy of the pencil beam algorithm in the presence of low-density inhomogeneities. Work supported by PHS grant CA10953 and CA81647 (NCI, DHHS)

  1. Monte Carlo simulation of the dose response of a novel 2D silicon diode array for use in hybrid MRI–LINAC systems

    SciTech Connect

    Gargett, Maegan Rosenfeld, Anatoly; Oborn, Brad; Metcalfe, Peter

    2015-02-15

    Purpose: MRI-guided radiation therapy systems (MRIgRT) are being developed to improve online imaging during treatment delivery. At present, the operation of single point dosimeters and an ionization chamber array have been characterized in such systems. This work investigates a novel 2D diode array, named “magic plate,” for both single point calibration and 2D positional performance, the latter being a key element of modern radiotherapy techniques that will be delivered by these systems. Methods: GEANT4 Monte Carlo methods have been employed to study the dose response of a silicon diode array to 6 MV photon beams, in the presence of in-line and perpendicularly aligned uniform magnetic fields. The array consists of 121 silicon diodes (dimensions 1.5 × 1.5 × 0.38 mm{sup 3}) embedded in kapton substrate with 1 cm pitch, spanning a 10 × 10 cm{sup 2} area in total. A geometrically identical, water equivalent volume was simulated concurrently for comparison. The dose response of the silicon diode array was assessed for various photon beam field shapes and sizes, including an IMRT field, at 1 T. The dose response was further investigated at larger magnetic field strengths (1.5 and 3 T) for a 4 × 4 cm{sup 2} photon field size. Results: The magic plate diode array shows excellent correspondence (< ± 1%) to water dose in the in-line orientation, for all beam arrangements and magnetic field strengths investigated. The perpendicular orientation, however, exhibits a dose shift with respect to water at the high-dose-gradient beam edge of jaw-defined fields [maximum (4.3 ± 0.8)% over-response, maximum (1.8 ± 0.8)% under-response on opposing side for 1 T, uncertainty 1σ]. The trend is not evident in areas with in-field dose gradients typical of IMRT dose maps. Conclusions: A novel 121 pixel silicon diode array detector has been characterized by Monte Carlo simulation for its performance inside magnetic fields representative of current prototype and proposed MRI

  2. Ultra high brightness laser diode arrays for pumping of compact solid state lasers and direct applications

    NASA Astrophysics Data System (ADS)

    Kohl, Andreas; Fillardet, Thierry; Laugustin, Arnaud; Rabot, Olivier

    2012-10-01

    High Power Laser Diodes (HPLD) are increasingly used in different fields of applications such as Industry, Medicine and Defense. Our significant improvements of performances (especially in power and efficiency) and a reproducible manufacturing process have led to reliable, highly robust components. For defense and security applications these devices are used predominantly for pumping of solid state lasers (ranging, designation, countermeasures, and sensors). Due to the drastically falling price per watt they are more and more replacing flash lamps as pump sources. By collimating the laser beam even with a bar to bar pitch of only 400μm. cutting edge brightness of our stacks.is achieved Due the extremely high brightness and high power density these stacks are an enabling technology for the development of compact highly efficient portable solid state lasers for applications as telemeters and designators on small platforms such as small UAVs and handheld devices. In combination with beam homogenizing optics their compact size and high efficiency makes these devices perfectly suited as illuminators for portable active imaging systems. For gated active imaging systems a very short pulse at high PRF operation is required. For this application we have developed a diode driver board with an efficiency several times higher than that of a standard driver. As a consequence this laser source has very low power consumption and low waste heat dissipation. In combination with its compact size and the integrated beam homogenizing optics it is therefore ideally suited for use in portable gated active imaging systems. The kWatt peak power enables a range of several hundred meters. The devices described in this paper mostly operate at wavelength between 800 nm and 980nm. Results from diodes operating between 1300 nm and 1550 nm are presented as well.

  3. Enhanced ultraviolet emission of ZnO microrods array based on Au surface plasmon

    NASA Astrophysics Data System (ADS)

    Feng, Wen-po; Jing, Ai-hua; Li, Jing-hua; Liang, Gao-feng

    2016-05-01

    In this work, the Au/ZnO hybrid microstructure was fabricated by assembling Au nanoparticles (NPs) onto the surface of ZnO microrods, and an obviously improved ultraviolet (UV) emission of ZnO is observed in the hybrid microstructure. About 27-fold enhancement ratio of the UV emission to the green band emission of ZnO is achieved. The underlying enhanced mechanism of the UV emission intensities can be ascribed to the charge transfer and the efficient coupling between ZnO excitons and Au surface plasmon (SP).

  4. Ultraviolet light-emitting diodes grown by plasma-assisted molecular beam epitaxy on semipolar GaN (2021) substrates

    SciTech Connect

    Sawicka, M.; Grzanka, S.; Skierbiszewski, C.; Turski, H.; Muziol, G.; Krysko, M.; Grzanka, E.; Sochacki, T.; Siekacz, M.; Kucharski, R.

    2013-03-18

    Multi-quantum well (MQW) structures and light emitting diodes (LEDs) were grown on semipolar (2021) and polar (0001) GaN substrates by plasma-assisted molecular beam epitaxy. The In incorporation efficiency was found to be significantly lower for the semipolar plane as compared to the polar one. The semipolar MQWs exhibit a smooth surface morphology, abrupt interfaces, and a high photoluminescence intensity. The electroluminescence of semipolar (2021) and polar (0001) LEDs fabricated in the same growth run peaks at 387 and 462 nm, respectively. Semipolar LEDs with additional (Al,Ga)N cladding layers exhibit a higher optical output power but simultaneously a higher turn-on voltage.

  5. Analysis of light emitting diode array lighting system based on human vision: normal and abnormal uniformity condition.

    PubMed

    Qin, Zong; Ji, Chuangang; Wang, Kai; Liu, Sheng

    2012-10-08

    In this paper, condition for uniform lighting generated by light emitting diode (LED) array was systematically studied. To take human vision effect into consideration, contrast sensitivity function (CSF) was novelly adopted as critical criterion for uniform lighting instead of conventionally used Sparrow's Criterion (SC). Through CSF method, design parameters including system thickness, LED pitch, LED's spatial radiation distribution and viewing condition can be analytically combined. In a specific LED array lighting system (LALS) with foursquare LED arrangement, different types of LEDs (Lambertian and Batwing type) and given viewing condition, optimum system thicknesses and LED pitches were calculated and compared with those got through SC method. Results show that CSF method can achieve more appropriate optimum parameters than SC method. Additionally, an abnormal phenomenon that uniformity varies with structural parameters non-monotonically in LALS with non-Lambertian LEDs was found and analyzed. Based on the analysis, a design method of LALS that can bring about better practicability, lower cost and more attractive appearance was summarized.

  6. Development of nanoscale Ni-embedded single-wall carbon nanotubes by electroless plating for transparent conductive electrodes of 375 nm AlGaN-based ultraviolet light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Park, Jun-Beom; Park, Hyung-Jo; Bae, Hyojung; Jeong, Tak; Han, Jong-Hun; Kwak, Joon Seop; Ha, Jun-Seok

    2016-08-01

    We propose a nanoscale Ni-embedded single-wall carbon nanotube (SWCNT) composite for transparent conductive electrodes (TCEs) of AlGaN-based ultraviolet light-emitting diodes (UV LEDs). TCEs specifically for the ultraviolet region were developed using Ni selectively electroless-plated SWCNTs. The nanoscale Ni of TCEs improved electrical conductivity and formed ohmic contact with p-GaN while minimizing transmittance loss. We applied Ni-embedded SWCNTs, SWCNTs, and Ni/Au to the TCEs of 375 nm UV LEDs. UV LEDs with Ni-embedded SWCNTs showed a 32% higher output power than UV LEDs with conventional Ni/Au TCEs.

  7. Compact intra-cavity frequency doubled line beam green laser by a laser diode array pumped

    NASA Astrophysics Data System (ADS)

    Yan, Boxia; Qi, Yan; Wang, Yanwei

    2016-10-01

    Compact, high power, and low-cost green laser light sources are needed in projection-related applications such as digital cinema, rear-projection television, simulators, and command and control stations. We report a LD array directly pumped intracavity SHG Nd:YVO4/PPMgLN laser without lens or waveguide in this letter. A compact 3.12 W green laser was demonstrated by intra-cavity frequency doubled using a PPMgLN bulk crystal by a 19-emitter LD array pumped(single bar), the conversion efficiency from input LD array was 9.2%. A line-beam output suitable for laser projectors was generated, which has the potential to be scalable to small volumes and low costs for laser projection displays.

  8. Quasi-isotropic VHF antenna array design study for the International Ultraviolet Explorer satellite

    NASA Technical Reports Server (NTRS)

    Raines, J. K.

    1975-01-01

    Results of a study to design a quasi-isotropic VHF antenna array for the IUE satellite are presented. A free space configuration was obtained that has no nulls deeper than -6.4 dbi in each of two orthogonal polarizations. A computer program named SOAP that analyzes the electromagnetic interaction between antennas and complicated conducting bodies, such as satellites was developed.

  9. Fabrication and characterization of p-ZnO:(P,N)/n-ZnO:Al homojunction ultra-violet (UV) light emitting diodes (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Rafiudeen, Amiruddin; Reddy, T. Srinivasa; Cheemadan, Shaheer; Kumar, M. C. Santhosh

    2015-10-01

    ZnO possess distinctive characteristics such as low cost, wide band gap (3.36 eV) and large exciton binding energy (60meV). As the band gap lies in ultra violet (UV) region, ZnO is considered as a novel material for the fabrication of ultra violet light emitting diodes (UV-LEDs). However, ZnO being intrinsic n-type semiconductor the key challenge lies in realization of stable and reproducible p-type ZnO. In the present research dual acceptor group-V elements such as P and N are simultaneously doped in ZnO films to obtain the p-type characteristics. The deposition is made by programmable spray pyrolysis technique upon glass substrates at 697K. The optimum doping concentration of P and N were found to be 0.75 at% which exhibits hole concentration of 4.48 x 10^18 cm-3 and resistivity value of 9.6 Ω.cm. The deposited p-ZnO were found to be stable for a period over six months. Highly conducting n-type ZnO films is made by doping aluminum (3 at%) which exhibits higher electron concentration of 1.52 x 10^19 cm-3 with lower electrical resistivity of 3.51 x 10-2 Ω.cm. The structural, morphological, optical and electrical properties of the deposited n-ZnO and p-ZnO thin films are investigated. An efficient p-n homojunction has been fabricated using the optimum p-ZnO:(P,N) and n-ZnO:Al layers. The current-voltage (I-V) characteristics show typical rectifying characteristics of p-n junction with a low turn on voltage. Electroluminescence (EL) studies reveals the fabricated p-n homojunction diodes exhibits strong emission features in ultra-violet (UV) region around 378 nm.

  10. Flexible one diode-one phase change memory array enabled by block copolymer self-assembly.

    PubMed

    Mun, Beom Ho; You, Byoung Kuk; Yang, Se Ryeun; Yoo, Hyeon Gyun; Kim, Jong Min; Park, Woon Ik; Yin, You; Byun, Myunghwan; Jung, Yeon Sik; Lee, Keon Jae

    2015-04-28

    Flexible memory is the fundamental component for data processing, storage, and radio frequency communication in flexible electronic systems. Among several emerging memory technologies, phase-change random-access memory (PRAM) is one of the strongest candidate for next-generation nonvolatile memories due to its remarkable merits of large cycling endurance, high speed, and excellent scalability. Although there are a few approaches for flexible phase-change memory (PCM), high reset current is the biggest obstacle for the practical operation of flexible PCM devices. In this paper, we report a flexible PCM realized by incorporating nanoinsulators derived from a Si-containing block copolymer (BCP) to significantly lower the operating current of the flexible memory formed on plastic substrate. The reduction of thermal stress by BCP nanostructures enables the reliable operation of flexible PCM devices integrated with ultrathin flexible diodes during more than 100 switching cycles and 1000 bending cycles.

  11. Broadband localized surface-plasmon-enhanced green light-emitting diodes by silver nanocone array

    NASA Astrophysics Data System (ADS)

    Liu, Hao; Li, Yufeng; Huang, Yaping; Wang, Shuai; Feng, Lungang; Gong, Zhina; Wang, Jiangteng; Ding, Wen; Zhang, Ye; Yun, Feng

    2015-12-01

    Green light-emitting diodes (LEDs) with silver nanocone-shaped structures embedded in p-GaN have been demonstrated with the surface plasmon (SP) enhancement effect. The resonance frequency has been broadened and the strength of coupling has been considerably enhanced. Compared with the LED without Ag nanocones, the integrated photoluminescence (PL) intensity of the SP-enhanced LED was improved by ∼275%, and the electroluminescence (EL) enhancement ratio at a different wavelength was evaluated at an injection current of 50 mA/mm2. At the same time, a reduction in the recombination lifetime indicated an increased internal quantum efficiency of LEDs. The results of simulation using nanocones as well as nanorods indicate good correlation with the experimental observation of the broadening effect. This structure is promising for converting incident photons into the localized surface plasmon (LSP) mode, to enhance the emission of LEDs within a broad wavelength range.

  12. Monolithic millimeter-wave diode array beam controllers: Theory and experiment

    NASA Technical Reports Server (NTRS)

    Sjogren, L. B.; Liu, H.-X. L.; Wang, F.; Liu, T.; Wu, W.; Qin, X.-H.; Chung, E.; Domier, C. W.; Luhmann, N. C., Jr.; Maserjian, J.

    1992-01-01

    In the current work, multi-function beam control arrays have been fabricated and have successfully demonstrated amplitude control of transmitted beams in the W and D bands (75-170 GHz). While these arrays are designed to provide beam control under DC bias operation, new designs for high-speed electronic and optical control are under development. These arrays will fill a need for high-speed watt-level beam switches in pulsed reflectometer systems under development for magnetic fusion plasma diagnostics. A second experimental accomplishment of the current work is the demonstration in the 100-170 GHz (D band) frequency range of a new technique for the measurement of the transmission phase as well as amplitude. Transmission data can serve as a means to extract ('de-embed') the grid parameters; phase information provides more complete data to assist in this process. Additional functions of the array beam controller yet to be tested include electronically controlled steering and focusing of a reflected beam. These have application in the areas of millimeter-wave electronic scanning radar and reflectometry, respectively.

  13. Quantum efficiency of opaque CsI photocathodes with channel electron multiplier arrays in the extreme and far ultraviolet

    NASA Technical Reports Server (NTRS)

    Martin, C.; Bowyer, S.

    1982-01-01

    The arrays are overcoated with a CsI photocathode in the VUV. The measurements are part of the development program for the Extreme Ultraviolet Explorer. Monochromatic light from a hollow cathode discharge source passing through a McPherson grazing incidence monochromator is used to illuminate the CsI photocathode. The beam diameter is kept small (approximately 2 mm) to confine it within the individual thickness strips. A bias grid is used to produce a 50-V/mm electric field to guarantee collection of all photoelectrons emitted by the CEMA (channel electron multiplier array) webbing. The CEMAs are operated with a gain of 2-3 x 10 to the 6th and are moderately saturated. A channeltron secondary transfer standard is used to determine the absolute QE in the EUV, whereas an NBS calibrated windowed photodiode is used to measure the FUV absolute QE. It is noted that the CsI gives a factor of 3 increase in the QE in the EUV and a factor of 50-5000 in the FUV.

  14. Feasibility of High-Power Diode Laser Array Surrogate to Support Development of Predictive Laser Lethality Model

    SciTech Connect

    Lowdermilk, W H; Rubenchik, A M; Springer, H K

    2011-01-13

    Predictive modeling and simulation of high power laser-target interactions is sufficiently undeveloped that full-scale, field testing is required to assess lethality of military directed-energy (DE) systems. The cost and complexity of such testing programs severely limit the ability to vary and optimize parameters of the interaction. Thus development of advanced simulation tools, validated by experiments under well-controlled and diagnosed laboratory conditions that are able to provide detailed physics insight into the laser-target interaction and reduce requirements for full-scale testing will accelerate development of DE weapon systems. The ultimate goal is a comprehensive end-to-end simulation capability, from targeting and firing the laser system through laser-target interaction and dispersal of target debris; a 'Stockpile Science' - like capability for DE weapon systems. To support development of advanced modeling and simulation tools requires laboratory experiments to generate laser-target interaction data. Until now, to make relevant measurements required construction and operation of very high power and complex lasers, which are themselves costly and often unique devices, operating in dedicated facilities that don't permit experiments on targets containing energetic materials. High power diode laser arrays, pioneered by LLNL, provide a way to circumvent this limitation, as such arrays capable of delivering irradiances characteristic of De weapon requires are self-contained, compact, light weight and thus easily transportable to facilities, such as the High Explosives Applications Facility (HEAF) at Lawrence Livermore National Laboratory (LLNL) where testing with energetic materials can be performed. The purpose of this study was to establish the feasibility of using such arrays to support future development of advanced laser lethality and vulnerability simulation codes through providing data for materials characterization and laser-material interaction

  15. Enhanced light extraction efficiency of chip-on board light-emitting diodes through micro-lens array fabricated by ion wind

    NASA Astrophysics Data System (ADS)

    Chu, Jingcao; Lei, Xiang; Wu, Jiading; Peng, Yang; Liu, Sheng; Yang, Qian; Zheng, Huai

    2017-03-01

    Low light extraction efficiency (LEE) is a key challenge of chip-on board (COB) packaging light-emitting diodes (LEDs). In this paper, a facile preparation of micro-lens array was proposed based on the ion wind patterning. The geometries and sizes of the micro-lens arrays were controlled through adjusting the voltage parameter of the ion wind generation. Consequently, the micro-lens array with the diameter of 180 μm and the gap distance of 15 μm has been fabricated. Benefitting from this micro-lens array, the LEE of COB packaging LEDs was enhanced by 9%. This facile fabrication of micro-lens array would be a promising method to improve the LEE of COB packaging LEDs.

  16. Atomically sharp 318 nm Gd:AlGaN ultraviolet light emitting diodes on Si with low threshold voltage

    NASA Astrophysics Data System (ADS)

    Kent, Thomas F.; Carnevale, Santino D.; Myers, Roberto C.

    2013-05-01

    Self-assembled AlxGa1-xN polarization-induced nanowire light emitting diodes (PINLEDs) with Gd-doped AlN active regions are prepared by plasma-assisted molecular beam epitaxy on Si substrates. Atomically sharp electroluminescence (EL) from Gd intra-f-shell electronic transitions at 313 nm and 318 nm is observed under forward biases above 5 V. The intensity of the Gd 4f EL scales linearly with current density and increases at lower temperature. The low field excitation of Gd 4f EL in PINLEDs is contrasted with high field excitation in metal/Gd:AlN/polarization-induced n-AlGaN devices; PINLED devices offer over a three fold enhancement in 4f EL intensity at a given device bias.

  17. P-type Cu--Ti--O nanotube arrays and their use in self-biased heterojunction photoelectrochemical diodes for hydrogen generation.

    PubMed

    Mor, Gopal K; Varghese, Oomman K; Wilke, Rudeger H T; Sharma, Sanjeev; Shankar, Karthik; Latempa, Thomas J; Choi, Kyoung-Shin; Grimes, Craig A

    2008-07-01

    Copper and titanium remain relatively plentiful in the earth's crust; hence, their use for large-scale solar energy conversion technologies is of significant interest. We describe fabrication of vertically oriented p-type Cu-Ti-O nanotube array films by anodization of copper rich (60% to 74%) Ti metal films cosputtered onto fluorine doped tin oxide (FTO) coated glass. Cu-Ti-O nanotube array films 1 mum thick exhibit external quantum efficiencies up to 11%, with a spectral photoresponse indicating that the complete visible spectrum, 380 to 885 nm, contributes significantly to the photocurrent generation. Water-splitting photoelectrochemical pn-junction diodes are fabricated using p-type Cu-Ti-O nanotube array films in combination with n-type TiO 2 nanotube array films. With the glass substrates oriented back-to-back, light is incident upon the UV absorbing n-TiO 2 side, with the visible light passing to the p-Cu-Ti-O side. In a manner analogous to photosynthesis, photocatalytic reactions are powered only by the incident light to generate fuel with oxygen evolved from the n-TiO 2 side of the diode and hydrogen from the p-Cu-Ti-O side. To date, we find under global AM 1.5 illumination that such photocorrosion-stable diodes generate a photocurrent of approximately 0.25 mA/cm (2), at a photoconversion efficiency of 0.30%.

  18. Multi-Spectral Solar Telescope Array. IV - The soft X-ray and extreme ultraviolet filters

    NASA Technical Reports Server (NTRS)

    Lindblom, Joakim F.; O'Neal, Ray H.; Walker, Arthur B. C., Jr.; Powell, Forbes R.; Barbee, Troy W., Jr.; Hoover, Richard B.

    1991-01-01

    NASA's Multi-Spectral Solar Telescope Array uses various combinations of thin foil filters composed of Al, C, Te, Be, Mo, Rh, and phthalocyanine to achieve the requisite radiation-rejection characteristics. Such rejection is demanded by the presence of strong EUV radiation at longer wavelengths where the specular reflectivity of multilayer mirrors can cause 'contamination' of the image in the narrow band defined by the Bragg condition.

  19. Selective-area growth of periodic nanopyramid light-emitting diode arrays on GaN/sapphire templates patterned by multiple-exposure colloidal lithography.

    PubMed

    Xiong, Zhuo; Wei, Tongbo; Zhang, Yonghui; Zhang, Xiang; Yang, Chao; Liu, Zhiqiang; Yuan, Guodong; Li, Jinmin; Wang, Junxi

    2017-03-17

    Gallium nitride-based nanopyramid light-emitting diodes are a promising technology to achieve highly efficient solid-state lighting and beyond. Here, periodic nanopyramid light-emitting diode arrays on gallium nitride/sapphire templates were fabricated by selective-area metalorganic chemical vapor deposition and multiple-exposure colloidal lithography. The electric field intensity distribution of incident light going through polystyrene microspheres and photoresist are simulated using finite-different time-domain method. Nitrogen as the carrier gas and a low V/III ratio (ratio of molar flow rate of group-V to group-III sources) are found to be important in order to form gallium nitride nanopyramid. In addition, a broad yellow emission in photoluminescence and cathodoluminescence spectra were observed. This phenomena showed the potential of nanopyramid light-emitting diodes to realize long wavelength visible emissions.

  20. Selective-area growth of periodic nanopyramid light-emitting diode arrays on GaN/sapphire templates patterned by multiple-exposure colloidal lithography

    NASA Astrophysics Data System (ADS)

    Xiong, Zhuo; Wei, Tongbo; Zhang, Yonghui; Zhang, Xiang; Yang, Chao; Liu, Zhiqiang; Yuan, Guodong; Li, Jinmin; Wang, Junxi

    2017-03-01

    Gallium nitride-based nanopyramid light-emitting diodes are a promising technology to achieve highly efficient solid-state lighting and beyond. Here, periodic nanopyramid light-emitting diode arrays on gallium nitride/sapphire templates were fabricated by selective-area metalorganic chemical vapor deposition and multiple-exposure colloidal lithography. The electric field intensity distribution of incident light going through polystyrene microspheres and photoresist are simulated using finite-different time-domain method. Nitrogen as the carrier gas and a low V/III ratio (ratio of molar flow rate of group-V to group-III sources) are found to be important in order to form gallium nitride nanopyramid. In addition, a broad yellow emission in photoluminescence and cathodoluminescence spectra were observed. This phenomena showed the potential of nanopyramid light-emitting diodes to realize long wavelength visible emissions.

  1. Performance improvement of AlGaN-based deep-ultraviolet light-emitting diodes via asymmetric step-like AlGaN quantum wells

    NASA Astrophysics Data System (ADS)

    Lu, Lin; Wan, Zhi; Xu, FuJun; Wang, XinQiang; Lv, Chen; Shen, Bo; Jiang, Ming; Chen, QiGong

    2017-04-01

    Characteristics of AlGaN-based deep-ultraviolet light-emitting diodes (DUV-LEDs) with light-emitting wavelength around 265 nm via step-like AlGaN quantum wells (QWs) have been investigated. Simulation approach yields a result that, there is significant enhancement of light output power (LOP) for DUV-LEDs with two-layer step-like AlGaN QWs compared to that with conventional one. The location and thickness of AlGaN layer with higher Al-content in the step-like QWs are confirmed to significantly affect the distributions and overlap of electron and hole wavefunctions. The best material characteristic is obtained when the step-like QW is designed as an asymmetric structure, such as Al0.74Ga0.26N (1.8 nm)/Al0.64Ga0.36N (1.2 nm), where AlGaN with higher Al-content layer is set to be located nearer from n-side and be thick as far as possible. The key factors for the performance improvements for this specific design is the enhanced hole transport and mitigated auger recombination.

  2. Disinfection of B. SUBTILIS Cells in Suspension Using Ultraviolet Light Emitting Diodes (leds) in the Presence of TiO2

    NASA Astrophysics Data System (ADS)

    Province, Dennis W.; O'Neil, Shannon; Higgins, Keri; Smith, Paul J.; Dooley, Kristin; Curtis, Joey; Grippo, Adam M.; Rino, John W.; Allen, Susan D.

    2011-06-01

    The concentration of vegetative Bacillus subtilis (B. subtilis) in phosphate buffered saline decreased when subjected to ultraviolet (UV) light from light emitting diodes (LEDs) in the presence of 0.01% Degussa P25 titanium dioxide (TiO2) as compared to a sample that contained bacteria only, a sample of bacteria that contained 0.01% TiO2, and bacteria that was subjected to the same UV light but no TiO2. The starting concentration of each sample was on the order of 104 colony forming units per milliliter (CFU/mL) and the time required for complete kill was less than 100min when the peak wavelength was 370 nm for the four LED light source at a total LED power of 0.8 milliWatts (mW), decreasing to less than 75 min for a total LED power of 3 mW. Changing the peak wavelength by 7 nm to 377 nm decreased the kill of vegetative B. subtilis to less than 1 log at 100 min for 5 mW total LED power. This work was performed under Federal Contract W9113M-09-C-0136 in support of the Radiance Technologies, Inc., prime contract from US Army SMDC, Huntsville, AL.

  3. Luminescent properties of Eu{sup 2+}-doped BaGdF{sub 5} glass ceramics a potential blue phosphor for ultra-violet light-emitting diode

    SciTech Connect

    Zhang, Weihuan; Zhang, Yuepin Ouyang, Shaoye; Zhang, Zhixiong; Wang, Qian; Xia, Haiping

    2015-01-14

    Eu{sup 2+} doped transparent oxyfluoride glass ceramics containing BaGdF{sub 5} nanocrystals were successfully fabricated by melt-quenching technique under a reductive atmosphere. The structure of the glass and glass ceramics were investigated by differential scanning calorimetry, X-ray diffraction (XRD), and transmission electron microscopy (TEM). The luminescent properties were investigated by transmission, excitation, and emission spectra. The decay time of the Gd{sup 3+} ions at 312 nm excited with 275 nm were also investigated. The results of XRD and TEM indicated the existence of BaGdF5 nanocrystals in the transparent glass ceramics. The excitation spectra of Eu{sup 2+} doped glass ceramics showed an excellent overlap with the main emission region of an ultraviolet light-emitting diode (UV-LED). Compared with the as-made glass, the emission of glass ceramics is much stronger by a factor of increasing energy transfer efficiency from Gd{sup 3+} to Eu{sup 2+} ions, the energy transfer efficiency from Gd{sup 3+} to Eu{sup 2+} ions was discussed. In addition, the chromaticity coordinates of glass and glass ceramics specimens were also discussed, which indicated that the Eu{sup 2+} doped BaGdF{sub 5} glass ceramics may be used as a potential blue-emitting phosphor for UV-LED.

  4. Electrical Current Leakage and Open-Core Threading Dislocations in AlGaN-Based Deep Ultraviolet Light-Emitting Diodes.

    DOE PAGES

    Moseley, Michael William; Allerman, Andrew A.; Crawford, Mary H.; ...

    2014-08-04

    Electrical current transport through leakage paths in AlGaN-based deep ultraviolet (DUV) lightemitting diodes (LEDs) and their effect on LED performance are investigated. Open-core threading dislocations, or nanopipes, are found to conduct current through nominally insulating Al0.7Ga0.3N layers and limit the performance of DUV-LEDs. A defect-sensitive phosphoric acid etch reveals these opencore threading dislocations in the form of large, micron-scale hexagonal etch pits visible with optical microscopy, while closed-core screw-, edge-, and mixed-type threading dislocations are represented by smaller and more numerous nanometer-scale pits visible by atomic-force microscopy. The electrical and optical performances of DUV-LEDs fabricated on similar Si-doped Al0.7Ga0.3N templatesmore » are found to have a strong correlation to the density of these nanopipes, despite their small fraction (<0.1% in this study) of the total density of threading dislocations.« less

  5. High efficiency improvements in AlGaN-based ultraviolet light-emitting diodes with specially designed AlGaN superlattice hole and electron blocking layers

    NASA Astrophysics Data System (ADS)

    Yi, Xinyan; Sun, Huiqing; Sun, Jie; Yang, Xian; Fan, Xuancong; Zhang, Zhuding; Guo, Zhiyou

    2017-04-01

    AlxGa1-xN/Al0.6Ga0.4N graded superlattice hole blocking layers (GSL-HBLs) and AlxGa1-xN/Al0.6Ga0.4N graded superlattice electron blocking layers (GSL-EBLs) are applied to the traditional AlGaN-based ultraviolet light-emitting diodes (UVLEDs). This can obtain much higher internal quantum efficiency (IQE) and output power. In order to reveal the underlying physical mechanism of this unique structure, we have studied it numerically by APSYS simulation programs. We find that GSL-EBLs can obviously increase the electron potential height and reduce the hole potential height, produce less electron leakage and more hole injection, leading to higher carrier contration. GSL-HBLs can obviously reduce the hole leakage, reduce the thermal velocity and correspondingly the mean free path of the hot electrons, and increase the electron injection. This enhanced the electron capture efficiency of the multiple quantum wells, which can also help to reduce electron leakage.

  6. Electrical current leakage and open-core threading dislocations in AlGaN-based deep ultraviolet light-emitting diodes

    SciTech Connect

    Moseley, Michael Allerman, Andrew; Crawford, Mary; Wierer, Jonathan J.; Smith, Michael; Biedermann, Laura

    2014-08-07

    Electrical current transport through leakage paths in AlGaN-based deep ultraviolet (DUV) light-emitting diodes (LEDs) and their effect on LED performance are investigated. Open-core threading dislocations, or nanopipes, are found to conduct current through nominally insulating Al{sub 0.7}Ga{sub 0.3}N layers and limit the performance of DUV-LEDs. A defect-sensitive phosphoric acid etch reveals these open-core threading dislocations in the form of large, micron-scale hexagonal etch pits visible with optical microscopy, while closed-core screw-, edge-, and mixed-type threading dislocations are represented by smaller and more numerous nanometer-scale pits visible by atomic-force microscopy. The electrical and optical performances of DUV-LEDs fabricated on similar Si-doped Al{sub 0.7}Ga{sub 0.3}N templates are found to have a strong correlation to the density of these nanopipes, despite their small fraction (<0.1% in this study) of the total density of threading dislocations.

  7. Formation of an indium tin oxide nanodot/Ag nanowire electrode as a current spreader for near ultraviolet AlGaN-based light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Park, Jae-Seong; Kim, Jae-Ho; Kim, Jun-Yong; Kim, Dae-Hyun; Na, Jin-Young; Kim, Sun-Kyung; Kang, Daesung; Seong, Tae-Yeon

    2017-01-01

    Indium tin oxide (ITO) nanodots (NDs) were combined with Ag nanowires (Ag NWs) as a p-type electrode in near ultraviolet AlGaN-based light-emitting diodes (LEDs) to increase light output power. The Ag NWs were 30 ± 5 nm in diameter and 25 ± 5 μm in length. The transmittance of 10 nm-thick ITO-only was 98% at 385 nm, while the values for ITO ND/Ag NW were 83%-88%. ITO ND/Ag NW films showed lower sheet resistances (32-51 Ω sq-1) than the ITO-only film (950 Ω sq-1). LEDs (chip size: 300 × 800 μm2) fabricated using the ITO NDs/Ag NW electrodes exhibited higher forward-bias voltages (3.52-3.75 V at 20 mA) than the LEDs with the 10 nm-thick ITO-only electrode (3.5 V). The LEDs with ITO ND/Ag NW electrodes yielded a 24%-62% higher light output power (at 20 mA) than those with the 10 nm-thick ITO-only electrode. Furthermore, finite-difference time-domain (FDTD) simulations were performed to investigate the extraction efficiency. Based on the emission images and FDTD simulations, the enhanced light output with the ITO ND/Ag NW electrodes is attributed to improved current spreading and better extraction efficiency.

  8. Electrical Current Leakage and Open-Core Threading Dislocations in AlGaN-Based Deep Ultraviolet Light-Emitting Diodes.

    SciTech Connect

    Moseley, Michael William; Allerman, Andrew A.; Crawford, Mary H.; Wierer, Jonathan; Smith, Michael L.; Biedermann, Laura

    2014-08-04

    Electrical current transport through leakage paths in AlGaN-based deep ultraviolet (DUV) lightemitting diodes (LEDs) and their effect on LED performance are investigated. Open-core threading dislocations, or nanopipes, are found to conduct current through nominally insulating Al0.7Ga0.3N layers and limit the performance of DUV-LEDs. A defect-sensitive phosphoric acid etch reveals these opencore threading dislocations in the form of large, micron-scale hexagonal etch pits visible with optical microscopy, while closed-core screw-, edge-, and mixed-type threading dislocations are represented by smaller and more numerous nanometer-scale pits visible by atomic-force microscopy. The electrical and optical performances of DUV-LEDs fabricated on similar Si-doped Al0.7Ga0.3N templates are found to have a strong correlation to the density of these nanopipes, despite their small fraction (<0.1% in this study) of the total density of threading dislocations.

  9. Ultraviolet InGaN and GaN Single-Quantum-Well-Structure Light-Emitting Diodes Grown on Epitaxially Laterally Overgrown GaN Substrates

    NASA Astrophysics Data System (ADS)

    Mukai, Takashi; Nakamura, Shuji

    1999-10-01

    Ultraviolet (UV) InGaN and GaN single-quantum-well-structure light-emitting diodes (LEDs) were grown on epitaxially laterally overgrown GaN (ELOG) and sapphire substrates. When the emission wavelength of UV InGaN LEDs was shorter than 380 nm, the external quantum efficiency (EQE) of the LED on ELOG was much higher than that on sapphire only under high-current operation. At low-current operation, both LEDs had the same EQE. When the active layer was GaN, EQE of the LED on sapphire was much lower than that on ELOG even under low-and high-current operations, due to the lack of localized energy states formed by alloy composition fluctuations. When the emission wavelengths were in the blue and green regions, EQE was almost the same between LEDs on both ELOG and sapphire due to a large number of deep localized energy states formed by large alloy composition fluctuations. The localized energy states are responsible for the high efficiency of InGaN-based LEDs in spite of a large number of dislocations.

  10. Efficiency improvement of GaN-based ultraviolet light-emitting diodes with reactive plasma deposited AlN nucleation layer on patterned sapphire substrate

    NASA Astrophysics Data System (ADS)

    Lee, Chia-Yu; Tzou, An-Jye; Lin, Bing-Cheng; Lan, Yu-Pin; Chiu, Ching-Hsueh; Chi, Gou-Chung; Chen, Chi-Hsiang; Kuo, Hao-Chung; Lin, Ray-Ming; Chang, Chun-Yen

    2014-09-01

    The flip chip ultraviolet light-emitting diodes (FC UV-LEDs) with a wavelength of 365 nm are developed with the ex situ reactive plasma deposited (RPD) AlN nucleation layer on patterned sapphire substrate (PSS) by an atmospheric pressure metal-organic chemical vapor deposition (AP MOCVD). The ex situ RPD AlN nucleation layer can significantly reduce dislocation density and thus improve the crystal quality of the GaN epitaxial layers. Utilizing high-resolution X-ray diffraction, the full width at half maximum of the rocking curve shows that the crystalline quality of the epitaxial layer with the (RPD) AlN nucleation layer is better than that with the low-temperature GaN (LT-GaN) nucleation layer. The threading dislocation density (TDD) is estimated by transmission electron microscopy (TEM), which shows the reduction from 6.8 × 107 cm-2 to 2.6 × 107 cm-2. Furthermore, the light output power (LOP) of the LEDs with the RPD AlN nucleation layer has been improved up to 30 % at a forward current of 350 mA compared to that of the LEDs grown on PSS with conventional LT-GaN nucleation layer.

  11. Coherent Beam Combining of High Power Broad-Area Laser Diode Array with a Closed-V-shape External Talbot Cavity

    SciTech Connect

    Liu, Bo; Liu, Yun; Braiman, Yehuda

    2010-01-01

    We have coherently combined a high-power broad-area laser diode array by using a feedback loop closed off-axis external Talbot cavity. The off-axis feedback from two gratings provides transverse-mode control of broad-area lasers. The Talbot configuration of the external cavity implements diffractive coupling among laser diodes. Feedback from two gratings increases external cavity quality factor and spectrum selection capability. As a result, spatial coherence was improved and spectral linewidth was narrowed down. The high visibility of the far-field profile indicates that high spatial coherence was achieved. We also observed symmetric far-field profiles indicating that laser array was phase locked to in-phase and out-of-phase super-modes, respectively. Transition between these super-modes was observed by tuning one grating's tilted angle.

  12. Coherent beam combining of high power broad-area laser diode array with a closed-V-shape external Talbot cavity.

    PubMed

    Liu, B; Liu, Y; Braiman, Y

    2010-03-29

    We have coherently combined a high-power broad-area laser diode array by using a feedback loop closed off-axis external Talbot cavity. The off-axis feedback from two gratings provides transverse-mode control of broad-area lasers. The Talbot configuration of the external cavity implements diffractive coupling among laser diodes. Feedback from two gratings increases external cavity quality factor and spectrum selection capability. As a result, spatial coherence was improved and spectral linewidth was narrowed down. The high visibility of the far-field profile indicates that high spatial coherence was achieved. We also observed symmetric far-field profiles indicating that laser array was phase locked to in-phase and out-of-phase super-modes, respectively. Transition between these super-modes was observed by tuning one grating's tilted angle.

  13. Improved high-performance liquid chromatography-diode array detection method for the determination of phenolic compounds in leaves and peels from different apple varieties.

    PubMed

    Kindt, Maddalena; Orsini, M Cristina; Costantini, Barbara

    2007-09-01

    Hydroxycinnamic acids derivatives, monomeric and oligomeric flavan-3-ols, flavonols, and dihydrocalcones are four of the major polyphenolic groups found in apples leaves and peels. A simple extraction with minimal pre-treatment and a high-performance liquid chromatography-diode array detection determination are optimized and validated, in order to identify and quantitate the polyphenolic profile of leaves and peels of four apples varieties (Gala, Topaz, Golden Delicious, and Florina). The improved chromatographic method has led to better separation of some known polyphenols in a single course, and diode-array detection has been used for the previsional identification of some polyphenolic compounds not available as standards. Because the mobile phase and the chromatographic column are compatible with a mass spectrometer, this method could investigate the unknown flavanols, flavonols, hydrocinnamic acid derivatives, and chalcone-related compounds found in apple leaves and peel extracts analyzed.

  14. Chemotaxonomic study of Chrysobalanus icaco Linnaeus (Chrysobalanaceae) using ultra high performance liquid chromatography coupled with diode array detection fingerprint in combination with multivariate analysis.

    PubMed

    Paracampo, Nádia Elígia Nunes Pinto; Prance, Ghillean Tolmie; Poppi, Ronei Jesus; da Silva, José Alberto Fracassi

    2017-03-29

    We investigated a strategy for the chemotaxonomy study of Chrysobalanus icaco Linnaeus (Chrysobalanaceae) based on ultra high performance liquid chromatography coupled with diode array detection fingerprint in combination with multivariate analysis. Two models using principal component analysis and partial least squares discriminant analysis were developed, and the samples could be successfully classified into two classes: Class 1 (red morphotype) and Class 2 (white and black morphotypes). Furthermore, ultra high performance liquid chromatography coupled with diode array and electrospray ionization tandem mass spectrometry was used to identify the main compounds responsible for class separation. The partial least squares discriminant analysis model accurately classified the C. icaco samples using an external validation subset with prediction ability of 100% and revealed the existence of two chemotypes. The most important finding obtained in this study is that the three morphotypes distinguished by the mature fruit color (white, red and black) are not all phytoequivalent to each other. This article is protected by copyright. All rights reserved.

  15. Fast separation of (poly)phenolic compounds from apples and pears by high-performance liquid chromatography with diode-array detection.

    PubMed

    Escarpa, A; González, M C

    1999-01-15

    Polyphenolic compounds in apples and pears were analysed by HPLC on C18-modified silica. Gradient elution with phosphoric acid-methanol mixtures and phosphoric acid-acetonitrile mixtures gave complete separation of all polyphenolics of interest. The use of methanol as modifier was preferred because it provides a more rapid separation (20 min). Diode-array detection was used for the provisional identification of polyphenolic compounds not available as standards.

  16. Photodegradation of E110 and E122 dyes in a commercial aperitif. A high performance liquid chromatography-diode array-tandem mass spectrometry study.

    PubMed

    Gosetti, F; Frascarolo, P; Mazzucco, E; Gianotti, V; Bottaro, M; Gennaro, M C

    2008-08-15

    A commercial aperitif containing E110 and E122 dyes is exposed to photo-irradiation in solar box under conditions chosen to simulate sun light irradiation. After 16 days of irradiation the red-coloured aperitif assumes a very pale yellow colour. HPLC-diode array-MS/MS analysis evidences the presence in the commercial aperitif of some impurities with naphthalene-based structures. The structures for the photodegradation products are proposed.

  17. Measurement of mounting-induced strain in high-power laser diode arrays

    NASA Astrophysics Data System (ADS)

    Tomm, Jens W.; Mueller, Ralf; Baerwolff, A.; Lorenzen, Dirk

    1999-11-01

    Thermally induced strain caused by device packaging is studied in high-power semiconductor laser arrays by a novel non-invasive technique. Measurements with intentionally strained laser array devices for 808 nm emission reveal spectral shifts of quantum-confined optical transitions in the optical active region. These shifts by up to 10 meV serve as a measure for strain and are compared with model calculations. We demonstrate that different packaging techniques cause different packaging-induced strains. We also show that the packaging-induced strain portion, which gets transmitted through the solder material, differs for different packaging technologies. An intentionally strain- reduced packaging technique is shown to transmit about one quarter of the potential packaging-induced strain towards the optical active layer, whereas another packaging technique, which provides highly reliable 'single-chip' devices is found to transmit about half of the potential amount. Spatially resolved measurements demonstrate strain gradients within the devices. Also temporal strain evolution is monitored. We show that 'the burn-in' is accompanied by strain accumulation whereas for long-term operation strain relaxation occurs.

  18. Regularly patterned non-polar InGaN/GaN quantum-well nanorod light-emitting diode array.

    PubMed

    Tu, Charng-Gan; Liao, Che-Hao; Yao, Yu-Feng; Chen, Horng-Shyang; Lin, Chun-Han; Su, Chia-Ying; Shih, Pei-Ying; Chen, Wei-Han; Zhu, Erwin; Kiang, Yean-Woei; Yang, C C

    2014-12-15

    The growth and process of a regularly patterned nanorod (NR)- light-emitting diode (LED) array with its emission from sidewall non-polar quantum wells (QWs) are demonstrated. A pyramidal un-doped GaN structure is intentionally formed at the NR top for minimizing the current flow through this portion of the NR such that the injection current can be effectively guided to the sidewall m-plane InGaN/GaN QWs for emission excitation by a conformal transparent conductor (GaZnO). The injected current density at a given applied voltage of the NR LED device is similar to that of a planar c-plane or m-plane LED. The blue-shift trend of NR LED output spectrum with increasing injection current is caused by the non-uniform distributions of QW width and indium content along the height on a sidewall. The photoluminescence spectral shift under reversed bias confirms that the emission of the fabricated NR LED comes from non-polar QWs.

  19. Screening method for the determination of tetracyclines and fluoroquinolones in animal drinking water by liquid chromatography with diode array detector.

    PubMed

    Patyra, E; Kowalczyk, E; Grelik, A; Przeniosło-Siwczyńska, M; Kwiatek, K

    2015-01-01

    A liquid chromatography - diode array detector (HPLC-DAD) procedure has been developed for the determination of oxytetracycline (OTC), tetracycline (TC), chlorotetracycline (CTC), doxycycline (DC), enrofloxacin (ENR), ciprofloxacin (CIP), sarafloxacin (SAR) and flumequine (FLU) residues in animal drinking water. This method was applied to animal drinking water. Solid-phase extraction (SPE) clean-up on an Oasis HLB cartridge allowed an extract suitable for liquid chromatographic analysis to be obtained. Chromatographic separation was carried out on a C18 analytical column, using gradient elution with 0.1% trifluoroacetic acid - acetonitrile - methanol at 30°C. The flow-rate was 0.7 mL/min and the eluate was analysed at 330 nm. The whole procedure was evaluated according to the requirements of the Commission Decision 2002/657/EC, determining specificity, decision limit (CCα), detection capacity (CCβ), limit of detection (LOD), limit of quantification (LOQ), precision and accuracy during validation of the method. The recoveries of TCs and FQs from spiked samples at the levels of 10, 100 and 1000 μg/L were higher than 82%. The developed method based on HPLC-DAD has been applied for the determination of four tetracyclines and four fluoroquinolones in animal drinking water samples.

  20. Trace analysis of fumagillin in honey by liquid chromatography-diode array-electrospray ionization mass spectrometry.

    PubMed

    Nozal, M A J; Bernal, J L; Martín, M A T; Bernal, J; Alvaro, A; Martín, R; Higes, M

    2008-05-09

    In this work a new liquid chromatography with diode array detection and electrospray ionization mass spectrometry (LC-DAD-ESI-MS) method has been developed for the determination of fumagillin residues in honey. This procedure involves a solid-phase extraction on polymeric cartridges for the isolation of fumagillin from diluted honey. Chromatographic separation of fumagillin was performed in isocratic mode, on a C(18) column (150 mm x 4.60mm i.d., 5 microm), the mobile phase consisted of a mixture of ammonium formate 20mM in water and acetonitrile (61/39, v/v), at 35 degrees C and the flow rate was set at 1.0 mL/min. Average analyte recoveries, influenced by the botanical origin were from 88 to 96% in replica sets of fortified honey samples. The detection limits of the LC-DAD-ESI-MS method were between 24 and 1 microg/kg for clear honeys (rosemary) and between 45 and 4 microg/kg for dark honeys (heather). The developed method has been applied to the analysis of fumagillin residues in honey samples collected from veterinary treated beehives, infected by Nosema ceranae and fed with the technical product at different doses.

  1. Application of RP-HPLC-diode array detector after SPE to the determination of pesticides in pepper samples.

    PubMed

    Tuzimski, Tomasz

    2012-01-01

    The application of HPLC-diode array detector (DAD) after SPE for identification and quantitative analysis of pesticides in red and green pepper samples is demonstrated. An HPLC procedure on an RP column (C18) was developed for analysis of selected pesticides from different chemical groups: metamitron, metalaxyl, linuron, and prometryn. Average recoveries for C18 Polar Plus cartridges and solvents by the proposed RP-HPLC-DAD method after SPE are presented. Average recoveries from the spiked samples and the SDs were 22.5 +/- 2.2, 138.0 +/- 4.1, 78.6 +/- 2.8, and 109.2 +/- 2.3% for metamitron, metalaxyl, linuron, and prometryn, respectively, at concentrations of 7 microg/g in the plant material. The efficiency of the SPE procedure was evaluated using real food samples. The quantities of prometryn, linuron, metalaxyl, and metamitron determined were in the ranges of 0.02-2.24 microg/g (n = 24), 0.08-1.01 microg/g (n = 9), 1.61-2.28 microg/g (n=4), and 0.05-1.07 microg/g (n = 3), respectively, in plant material sampled in 2011. The method was validated for precision, repeatability, and accuracy.

  2. Commissioning and comprehensive evaluation of the ArcCHECK cylindrical diode array for VMAT pretreatment delivery QA.

    PubMed

    Chaswal, Vibha; Weldon, Michael; Gupta, Nilendu; Chakravarti, Arnab; Rong, Yi

    2014-07-08

    We present commissioning and comprehensive evaluation for ArcCHECK as a QA equipment for volumetric-modulated arc therapy (VMAT), using the 6 MV photon beam with and without the flattening filter, and the SNC patient software (version 6.2). In addition to commissioning involving absolute dose calibration, array calibration, and PMMA density verification, ArcCHECK was evaluated for its response dependency on linac dose rate, instantaneous dose rate, radiation field size, beam angle, and couch insertion. Scatter dose characterization, consistency and symmetry of response, and dosimetry accuracy evaluation for fixed aperture arcs and clinical VMAT patient plans were also investigated. All the evaluation tests were performed with the central plug inserted and the homogeneous PMMA density value. Results of gamma analysis demonstrated an overall agreement between ArcCHECK-measured and TPS-calculated reference doses. The diode based field size dependency was found to be within 0.5% of the reference. The dose rate-based dependency was well within 1% of the TPS reference, and the angular dependency was found to be ± 3% of the reference, as tested for BEV angles, for both beams. Dosimetry of fixed arcs, using both narrow and wide field widths, resulted in clinically acceptable global gamma passing rates on the 3%/3mm level and 10% threshold. Dosimetry of narrow arcs showed an improvement over published literature. The clinical VMAT cases demonstrated high level of dosimetry accuracy in gamma passing rates.

  3. Liquid chromatographic-diode-array detection multiresidue determination of rice herbicides in drinking and paddy-field water.

    PubMed

    Roehrs, Rafael; Zanella, Renato; Pizzuti, Ionara; Adaime, Martha B; Pareja, Lucía; Niell, Silvina; Cesio, María V; Heinzen, Horacio

    2009-01-01

    A sensitive, rapid, and simple multiresidue method for the simultaneous determination of six postemergence herbicides currently used in rice cultivation--metsulfuron methyl, bensulfuron methyl, pyrazosulfuron ethyl, bentazone, bispyribac sodium, and cyhalofop butyl--in drinking and paddy-field water is presented. Water samples were extracted with solid-phase extraction cartridges. Final determination was made by LC with diode-array detection. The extraction efficiencies of C18 and HLB cartridges were compared. The average recovery obtained for these compounds for the lowest spiked level (0.1 microg/L) varied from 70 to 122% for C18 and 75-119% for HLB, with RSDs of 11 and 8.3%, respectively. The method had good linearity, and the lower detection limit for the pesticides studied varied from 0.03 to 0.04 microg/L. The proposed method was also tested in paddy-field water, with recovery studies giving good results with low RSDs at 1.0 microg/L.

  4. Liquid chromatography-diode array detection-mass spectrometry for compositional analysis of low molecular weight heparins.

    PubMed

    Wang, Zhangjie; Li, Daoyuan; Sun, Xiaojun; Bai, Xue; Jin, Lan; Chi, Lianli

    2014-04-15

    Low molecular weight heparins (LMWHs) are important artificial preparations from heparin polysaccharide and are widely used as anticoagulant drugs. To analyze the structure and composition of LMWHs, identification and quantitation of their natural and modified building blocks are indispensable. We have established a novel reversed-phase high-performance liquid chromatography-diode array detection-electrospray ionization-mass spectrometry approach for compositional analysis of LMWHs. After being exhaustively digested and labeled with 2-aminoacridone, the structural motifs constructing LMWHs, including 17 components from dalteparin and 15 components from enoxaparin, were well separated, identified, and quantified. Besides the eight natural heparin disaccharides, many characteristic structures from dalteparin and enoxaparin, such as modified structures from the reducing end and nonreducing end, 3-O-sulfated tetrasaccharides, and trisaccharides, have been unambiguously identified based on their retention time and mass spectra. Compared with the traditional heparin compositional analysis methods, the approach described here is not only robust but also comprehensive because it is capable of identifying and quantifying nearly all components from lyase digests of LMWHs.

  5. High-performance liquid chromatography with diode-array detection cotinine method adapted for the assessment of tobacco smoke exposure.

    PubMed

    Bartolomé, Mónica; Gallego-Picó, Alejandrina; Huetos, Olga; Castaño, Argelia

    2014-06-01

    Smoking is considered to be one of the main risk factors for cancer and other diseases and is the second leading cause of death worldwide. As the anti-tobacco legislation implemented in Europe has reduced secondhand smoke exposure levels, analytical methods must be adapted to these new levels. Recent research has demonstrated that cotinine is the best overall discriminator when biomarkers are used to determine whether a person has ongoing exposure to tobacco smoke. This work proposes a sensitive, simple and low-cost method based on solid-phase extraction and liquid chromatography with diode array detection for the assessment of tobacco smoke exposure by cotinine determination in urine. The analytical procedure is simple and fast (20 min) when compared to other similar methods existing in the literature, and it is cheaper than the mass spectrometry techniques usually used to quantify levels in nonsmokers. We obtained a quantification limit of 12.30 μg/L and a recovery of over 90%. The linearity ranges used were 12-250 and 250-4000 μg/L. The method was successfully used to determine cotinine in urine samples collected from different volunteers and is clearly an alternative routine method that allows active and passive smokers to be distinguished.

  6. Determination of insulin in humans with insulin-dependent diabetes mellitus patients by HPLC with diode array detection.

    PubMed

    Yilmaz, Bilal; Kadioglu, Yucel; Capoglu, Ilyas

    2012-08-01

    A simple and reliable high-performance liquid chromatographic method with diode array detection has been developed and validated for the determination of insulin in human plasma. A good chromatographic separation was achieved on a C18 column with a mobile phase consisting of acetonitrile and 0.2M sodium sulfate (pH 2.4), 25:75 (v/v). Its flow rate was 1.2 mL/min. Calibration curve was linear within the concentration range of 0.15-25 µg/mL. Intra-day and inter-day relative standard deviations for insulin in human plasma were less than 6.3 and 8.5%, respectively. The limits of detection and quantification of insulin were 0.10 and 0.15 µg/mL, respectively. Also, this assay was applied to determine the pharmacokinetic parameters of insulin in eight insulin-dependent diabetes mellitus patients after subcutaneous injection of 25 IU of Actrapid HM.

  7. Selective carrier injection into patterned arrays of pyramidal quantum dots for entangled photon light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Chung, T. H.; Juska, G.; Moroni, S. T.; Pescaglini, A.; Gocalinska, A.; Pelucchi, E.

    2016-12-01

    Scalability and foundry compatibility (as apply to conventional silicon-based integrated computer processors, for example) in developing quantum technologies are major challenges facing current research. Here we introduce a quantum photonic technology that has the potential to enable the large-scale fabrication of semiconductor-based, site-controlled, scalable arrays of electrically driven sources of polarization-entangled photons that may be able to encode quantum information. The design of the sources is based on quantum dots grown in micrometre-sized pyramidal recesses along the crystallographic direction (111)B, which theoretically ensures high symmetry of the quantum dots—a requirement for bright entangled-photon emission. A selective electric injection scheme in these non-planar structures allows a high density of light-emitting diodes to be obtained, with some producing entangled photon pairs that also violate Bell's inequality. Compatibility with semiconductor fabrication technology, good reproducibility and lithographic position control make these devices attractive candidates for integrated photonic circuits for quantum information processing.

  8. Quantification of polyacetylenes in apiaceous plants by high-performance liquid chromatography coupled with diode array detection.

    PubMed

    Kramer, Maike; Mühleis, Andrea; Conrad, Jürgen; Leitenberger, Martin; Beifuss, Uwe; Carle, Reinhold; Kammerer, Dietmar R

    2011-01-01

    Polyacetylenes are known for their biofunctional properties in a wide range of organisms. In the present study, the most frequently occurring polyacetylenes, i.e. falcarinol, falcarindiol, and falcarindiol-3-acetate, were determined in six genera of the Apiaceae family. For this purpose, a straightforward and reliable method for the screening and quantification of the polyacetylenes using high-performance liquid chromatography coupled with diode array and mass spectrometric detection without tedious sample clean-up has been developed. Peak assignment was based on retention times, UV spectra, and mass spectral data. Quantification was carried out using calibration curves of authentic standards isolated from turnip-rooted parsley and Ligusticum mutellina, respectively. The references were unambiguously identified by Fourier transform-IR (FT-IR) spectroscopy, GC-MS, HPLC-MSn in the positive ionization mode, and 1H NMR and 13C NMR spectroscopy. To the best of our knowledge, the occurrence of falcarindiol-3-acetate in Anthriscus sylvestris and Pastinaca sativa has been reported for the first time. The data revealed great differences in the polyacetylene contents and varying proportions of individual compounds in the storage roots of Apiaceous plants. The results of the present study may be used as a suitable tool for authenticity control and applied to identify novel sources devoid or particularly rich in polyacetylenes, thus facilitating breeding programs for the selective enrichment and depletion of these plant secondary metabolites, respectively.

  9. Determination of polyacetylenes in carrot roots (Daucus carota L.) by high-performance liquid chromatography coupled with diode array detection.

    PubMed

    Christensen, Lars P; Kreutzmann, Stine

    2007-03-01

    A new high-performance liquid chromatographic method with diode array detection was developed for the separation and simultaneous determination of the carrot polyacetylenes falcarindiol (FaDOH), falcarindiol 3-acetate (FaDOAc) and falcarinol (FaOH) in carrot root extracts. The optimal chromatographic conditions were achieved on a C18 column with a linear gradient elution of water and acetonitrile as mobile phases, at the flow rate of 1.0 mL/min. All calibration curves of the three carrot polyacetylenes showed good linear regression (R2 > 0.998) within the test ranges. The developed method showed good precision for quantification of all polyacetylenes with overall intraday and interday variation of less than 3.3% and with average recovery rates of 99.2, 96.8 and 99.7% for FaDOH, FaDOAc and FaOH, respectively. The LOD (S/N = 3) and LOQ (S/N = 10) were less than 0.19 and 0.42 microg/mL, respectively, for all analytes. The established method was successfully used to determine the spatial distribution of FaDOH, FaDOAc and FaOH in six carrot genotypes (Bolero, Independent, Line 1, Mello Yello, Purple Haze and Tornado) by analysing peeled carrots and the corresponding peels for these polyacetylenes.

  10. Vacuum ultraviolet radiation and thermal cycling effects on atomic oxygen protective photovoltaic array blanket materials

    NASA Technical Reports Server (NTRS)

    Brady, J.; Banks, B.

    1990-01-01

    The importance of synergistic environmental exposure is demonstrated through the evaluation of DuPont 93-1 in simulated LEO environment. Changes in optical properties, surface condition, and mass loss data are described. The qualitative results indicate the necessity for exposure of materials to a series of simulated LEO environments in order to properly determine synergistic effects and demonstrate the overall LEO durability of candidate materials. It is shown that synergistic effects may occur with vacuum thermal cycling combined with VUV radiation followed by atomic oxygen exposure. Testing the durability of candidate solar array blanket materials in a test sequence with necessary synergistic effects makes it possible to determine the appropriate material for providing structural support and maintaining the proper operating temperature for solar cells in the SSF Photovaltaic Power System.

  11. Performance of 128×128 solar-blind AlGaN ultraviolet focal plane arrays

    NASA Astrophysics Data System (ADS)

    Yuan, Yongang; Zhang, Yan; Liu, Dafu; Chu, Kaihui; Wang, Ling; Li, Xiangyang

    2009-07-01

    Ozone layer intensively absorbs 240nm to 285 nm incidence, when the sunshine goes through stratospheric. There is almost no UVC (200nm-280nm) band radiation existing below stratospheric. Because the radiation target presents a strong contrast between atmosphere and background, solar-blind band radiation is very useful. Wide band gap materials, especially III-V nitride materials, have attracted extensive interest. The direct band gap of GaN and A1N is 3.4 and 6.2 eV, respectively. Since they are miscible with each other and form a complete series of AlGaN alloys, AlGaN has direct band gaps from 3.4 to 6.2 eV, corresponding to cutoff wavelengths from 365 to 200 nm. A back-illuminated hybrid FPA has been developed by Shanghai Institute of Technical Physics Chinese Academy of Science. This paper reports the performance of the 128x128 solar-blind AlGaN UV Focal Plane Arrays (FPAs). More and more a CTIA (capacitivetransimpedance) readout circuit architecture has been proven to be well suited for AlGaN detectors arrays. The bared readout circuit was first tested to find out optimal analog reference voltage. Second, this ROIC was tested in a standard 20-pin shielded dewar at 115 K to 330K. Then, a new test system was set up to obtain test UV FPA noise, swing voltage, data valid time, operating speed, dynamic range, UV response etc. The results show that 128x128 back-illuminated AlGaN PIN detector SNR is as high as 74db at the speed of above30 frame per second. Also, some noise test method is mentioned.

  12. Improving the optical performance of InGaN light-emitting diodes by altering light reflection and refraction with triangular air prism arrays.

    PubMed

    Kang, Ji Hye; Kim, Hyung Gu; Chandramohan, S; Kim, Hyun Kyu; Kim, Hee Yun; Ryu, Jae Hyoung; Park, Young Jae; Beak, Yun Seon; Lee, Jeong-Sik; Park, Joong Seo; Lysak, Volodymyr V; Hong, Chang-Hee

    2012-01-01

    The effect of triangular air prism (TAP) arrays with different distance-to-width (d/w) ratios on the enhancement of light extraction efficiency (LEE) of InGaN light-emitting diodes (LEDs) is investigated. The TAP arrays embedded at the sapphire/GaN interface act as light reflectors and refractors, and thereby improve the light output power due to the redirection of light into escape cones on both the front and back sides of the LED. Enhancement in radiometric power as high as 117% and far-field angle as low as 129° are realized with a compact arrangement of TAP arrays compared with that of a conventional LED made without TAP arrays under an injection current of 20 mA.

  13. Micro-lens array design on a flexible light-emitting diode package for indoor lighting.

    PubMed

    Lee, Hsiao-Wen; Lin, Bor-Shyh

    2015-10-01

    An advanced, ultra-thin, flexible LED (FLED) package technique is first proposed in this study, where a polyimide substrate was used as the lead frame package material due to its physical stability in thermal processing. The experimental results showed that the thickness of the mockup sample measured by a vernier caliper was 260 μm and 35% thinner than the Panasonic organic LED lighting panel announced on 4 March 2014 in Tokyo. Moreover, the flexible angle of the ultra-thin LED package was 200.54° when it surrounded a disk with a 1 cm radius. A design of a micro-lens array manufactured by silicone molding on the FLED is also proposed in this study. Finally, different types of micro-lenses were applied to different lighting regions to investigate their lighting effects.

  14. Self-powered ultraviolet photodetectors based on selectively grown ZnO nanowire arrays with thermal tuning performance.

    PubMed

    Bai, Zhiming; Chen, Xiang; Yan, Xiaoqin; Zheng, Xin; Kang, Zhuo; Zhang, Yue

    2014-05-28

    A self-powered Schottky-type ultraviolet photodetector with Al-Pt interdigitated electrodes has been fabricated based on selectively grown ZnO nanowire arrays. At zero bias, the fabricated photodetector exhibited high sensitivity and excellent selectivity to UV light illumination with a fast response time of 81 ms. By tuning the Schottky barrier height through the thermally induced variation of the interface chemisorbed oxygen, an ultrahigh sensitivity of 3.1 × 10(4) was achieved at 340 K without an external power source, which was 82% higher than that obtained at room temperature. According to the thermionic emission-diffusion theory and the solar cell theory, the changes in the photocurrent of the photodetector at zero bias with various system temperatures were calculated, which agreed well with the experimental data. This work demonstrates a promising approach to modulating the performance of a self-powered photodetector by heating and provides theoretical support for studying the thermal effect on the future photoelectric device.

  15. Design and characterization of indium gallium arsenic phosphide/indium phosphide and indium(aluminum) gallium arsenic antimonide/gallium antimonide laser diode arrays

    NASA Astrophysics Data System (ADS)

    Gourevitch, Alexandre

    2006-12-01

    Semiconductor laser diodes and laser diode arrays are efficient electrical to optical power converters providing their output energy in relatively narrow emission spectra. The different wavelength ranges are well covered by different semiconductor materials. InP-based laser diodes cover the wavelength range from 1-mum to 2-mum. The region between 2 and 3-mum is well handled by type-I devices based on the GaSb material system. We designed, fabricated and characterized InP-based and GaSb-based laser arrays with record high continuous wave output power emitting at 1.5-mum and 2.3-mum, correspondingly. A laser array based on the InGaAsP/InP material system was developed for optical pumping of erbium doped solid state lasers emitting eye-safe light around 1.6-mum. The 2.3-mum laser arrays can be used for optical pumping of recently developed type-II semiconductor lasers operating in the mid-infrared atmospheric transparency window between 3.5-mum and 5-mum. Optical pumping requires pump sources that reliably provide output energy in a relatively narrow spectral range matching with absorption bands of illuminated materials. Also the compact size of laser diodes and laser arrays is preferable and convenient in different implementations, but it leads to significant overheating in high power operations. The inherent properties of semiconductor materials result in a red-shift of the laser emission spectrum with increased temperature. This thermal drift of the laser emission spectrum can lead to misalignment with the narrow absorption bands of illuminated material. We have developed an experimental technique to measure the time-resolved evolution of the laser emission spectrum. The data obtained from the emission spectrum measurements have been used to optimize the laser device design. In this dissertation the progress in the development of high-power infrared laser arrays have been discussed. The different aspects of laser array design, thermal analysis and laser bar

  16. High-temperature operation of 640 nm wavelength high-power laser diode arrays

    NASA Astrophysics Data System (ADS)

    Imanishi, Daisuke

    2017-03-01

    We realized the fabrication of a red semiconductor laser array with high optical power and reliability using an AlGaInP-based compound semiconductor. To obtain a high optical output, the semiconductor laser requires high-quality quantum wells. In this work, we improved quantum well layer abruptness by applying high-temperature growth condition to quantum wells. We obtained a very high optical power of 20.1 W with a wavelength of 644 nm under this growth condition using magnesium as a dopant for a p-type layer. As a results, we achieved a high characteristic temperature of 68 K and a high electrical-to-optical (E–O) conversion efficiency 37% at 15 W optical output. When the laser lifetime at a temperature of 35 °C and an optical output power of 6.6 W for operation is defined as the time when the output power decreases to 50%, which is usually used for defining the lifetime of ultra high-pressure (UHP) lamps in projection display, we can estimate the lifetime of this laser to be longer than 10000 h or more.

  17. Diode Characteristics Approaching Bulk Limits in GaAs Nanowire Array Photodetectors.

    PubMed

    Farrell, Alan C; Senanayake, Pradeep; Meng, Xiao; Hsieh, Nick Y; Huffaker, Diana L

    2017-04-12

    We present the electrical properties of p-n junction photodetectors comprised of vertically oriented p-GaAs nanowire arrays on the n-GaAs substrate. We measure an ideality factor as low as n = 1.0 and a rectification ratio >10(8) across all devices, with some >10(9), comparable to the best GaAs thin film photodetectors. An analysis of the Arrhenius plot of the saturation current yields an activation energy of 690 meV-approximately half the bandgap of GaAs-indicating generation-recombination current from midgap states is the primary contributor to the leakage current at low bias. Using fully three-dimensional electrical simulations, we explain the lack of a recombination current dominated regime at low forward bias, as well as some of the issues related to analysis of the capacitance-voltage characteristics of nanowire devices. This work demonstrates that, through proper design and fabrication, nanowire-based devices can perform as well as their bulk device counterparts.

  18. Effects of GaN/AlGaN/Sputtered AlN nucleation layers on performance of GaN-based ultraviolet light-emitting diodes

    PubMed Central

    Hu, Hongpo; Zhou, Shengjun; Liu, Xingtong; Gao, Yilin; Gui, Chengqun; Liu, Sheng

    2017-01-01

    We report on the demonstration of GaN-based ultraviolet light-emitting diodes (UV LEDs) emitting at 375 nm grown on patterned sapphire substrate (PSS) with in-situ low temperature GaN/AlGaN nucleation layers (NLs) and ex-situ sputtered AlN NL. The threading dislocation (TD) densities in GaN-based UV LEDs with GaN/AlGaN/sputtered AlN NLs were determined by high-resolution X-ray diffraction (XRD) and cross-sectional transmission electron microscopy (TEM), which revealed that the TD density in UV LED with AlGaN NL was the highest, whereas that in UV LED with sputtered AlN NL was the lowest. The light output power (LOP) of UV LED with AlGaN NL was 18.2% higher than that of UV LED with GaN NL owing to a decrease in the absorption of 375 nm UV light in the AlGaN NL with a larger bandgap. Using a sputtered AlN NL instead of the AlGaN NL, the LOP of UV LED was further enhanced by 11.3%, which is attributed to reduced TD density in InGaN/AlInGaN active region. In the sputtered AlN thickness range of 10–25 nm, the LOP of UV LED with 15-nm-thick sputtered AlN NL was the highest, revealing that optimum thickness of the sputtered AlN NL is around 15 nm. PMID:28294166

  19. Effects of GaN/AlGaN/Sputtered AlN nucleation layers on performance of GaN-based ultraviolet light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Hu, Hongpo; Zhou, Shengjun; Liu, Xingtong; Gao, Yilin; Gui, Chengqun; Liu, Sheng

    2017-03-01

    We report on the demonstration of GaN-based ultraviolet light-emitting diodes (UV LEDs) emitting at 375 nm grown on patterned sapphire substrate (PSS) with in-situ low temperature GaN/AlGaN nucleation layers (NLs) and ex-situ sputtered AlN NL. The threading dislocation (TD) densities in GaN-based UV LEDs with GaN/AlGaN/sputtered AlN NLs were determined by high-resolution X-ray diffraction (XRD) and cross-sectional transmission electron microscopy (TEM), which revealed that the TD density in UV LED with AlGaN NL was the highest, whereas that in UV LED with sputtered AlN NL was the lowest. The light output power (LOP) of UV LED with AlGaN NL was 18.2% higher than that of UV LED with GaN NL owing to a decrease in the absorption of 375 nm UV light in the AlGaN NL with a larger bandgap. Using a sputtered AlN NL instead of the AlGaN NL, the LOP of UV LED was further enhanced by 11.3%, which is attributed to reduced TD density in InGaN/AlInGaN active region. In the sputtered AlN thickness range of 10–25 nm, the LOP of UV LED with 15-nm-thick sputtered AlN NL was the highest, revealing that optimum thickness of the sputtered AlN NL is around 15 nm.

  20. Effectiveness and intermediates of microcystin-LR degradation by UV/H2O2 via 265 nm ultraviolet light-emitting diodes.

    PubMed

    Liu, Juan; Ye, Jin-Shao; Ou, Hua-Se; Lin, Jialing

    2017-02-01

    Although the degradation of cyanotoxins by 254 nm UV/H2O2 has been well elucidated, the efficiency and mechanism involved are not necessarily true for other UV wavelengths. The degradation of microcystin-LR (MC-LR), a representative cyanotoxin, was explored by UV/H2O2 using 265 nm ultraviolet light-emitting diode (UV-LED). The results indicated that 265 nm UV/H2O2 treatment had a high removal efficiency of MC-LR ([MC-LR] = 0.1 μM, apparent rate constants reached 0.2077 min(-1), half-time at 3.3 min). The qualitative analyses demonstrated that three novel intermediates, C48H74N10O15 (molecular weight = 1030.5335), C36H58N10O14 (854.4134), and C33H54N10O14 (814.3821), were generated in 265 nm UV/H2O2. Five published intermediates were also confirmed. The generative pathway of these products mainly involved free hydroxyl radical oxidation, resulting in consecutive hydroxyl substitutions and hydroxyl additions of unsaturated bonds in MC-LR. The toxicity of MC-LR was weaken with a relative low mineralization. The electrical energy per order values were calculated to be in the range of 0.00447 to 0.00612 kWh m(-3) order(-1) for 100-5000 μg L(-1) MC-LR. Overall, 265 nm UV-LED/H2O2 can be used as an alternative effective technology to improve the removal efficiency of MC-LR in water.

  1. Variation of the external quantum efficiency with temperature and current density in red, blue, and deep ultraviolet light-emitting diodes

    SciTech Connect

    Park, Jun Hyuk; Lee, Jong Won; Kim, Dong Yeong; Kim, Jong Kyu; Cho, Jaehee; Schubert, E. Fred; Kim, Jungsub; Lee, Jinsub; Kim, Yong-Il; Park, Youngsoo

    2016-01-14

    The temperature-dependent external quantum efficiencies (EQEs) were investigated for a 620 nm AlGaInP red light-emitting diodes (LEDs), a 450 nm GaInN blue LED, and a 285 nm AlGaN deep-ultraviolet (DUV) LED. We observed distinct differences in the variation of the EQE with temperature and current density for the three types of LEDs. Whereas the EQE of the AlGaInP red LED increases as temperature decreases below room temperature, the EQEs of GaInN blue and AlGaN DUV LEDs decrease for the same change in temperature in a low-current density regime. The free carrier concentration, as determined from the dopant ionization energy, shows a strong material-system-specific dependence, leading to different degrees of asymmetry in carrier concentration for the three types of LEDs. We attribute the EQE variation of the red, blue, and DUV LEDs to the different degrees of asymmetry in carrier concentration, which can be exacerbated at cryogenic temperatures. As for the EQE variation with temperature in a high-current density regime, the efficiency droop for the AlGaInP red and GaInN blue LEDs becomes more apparent as temperature decreases, due to the deterioration of the asymmetry in carrier concentration. However, the EQE of the AlGaN DUV LED initially decreases, then reaches an EQE minimum point, and then increases again due to the field-ionization of acceptors by the Poole-Frenkel effect. The results elucidate that carrier transport phenomena allow for the understanding of the droop phenomenon across different material systems, temperatures, and current densities.

  2. The effect of free-standing GaN substrate on carrier localization in ultraviolet InGaN light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Tsai, Ming-Ta; Chu, Chung-Ming; Huang, Che-Hsuan; Wu, Yin-Hao; Chiu, Ching-Hsueh; Li, Zhen-Yu; Tu, Po-Min; Lee, Wei-I.; Kuo, Hao-Chung

    2014-12-01

    In this study, we have grown 380-nm ultraviolet light-emitting diodes (UV-LEDs) based on InGaN/AlInGaN multiple quantum well (MQW) structures on free-standing GaN (FS-GaN) substrate by atmospheric pressure metal-organic chemical vapor deposition (AP-MOCVD), and investigated the relationship between carrier localization degree and FS-GaN. The micro-Raman shift peak mapping image shows low standard deviation (STD), indicating that the UV-LED epi-wafer of low curvature and MQWs of weak quantum-confined Stark effect (QCSE) were grown. High-resolution X-ray diffraction (HRXRD) analyses demonstrated high-order satellite peaks and clear fringes between them for the UV-LEDs grown on the FS-GaN substrate, from which the interface roughness (IRN) was estimated. The temperature-dependent photoluminescence (PL) measurement confirmed that the UV-LEDs grown on the FS-GaN substrate exhibited better carrier confinement. Besides, the high-resolution transmission electron microscopy (HRTEM) and energy-dispersive spectrometer (EDS) mapping images verified that the UV-LEDs on FS-GaN have fairly uniform distribution of indium and more ordered InGaN/AlInGaN MQW structure. Clearly, the FS-GaN can not only improve the light output power but also reduce the efficiency droop phenomenon at high injection current. Based on the results mentioned above, the FS-GaN can offer UV-LEDs based on InGaN/AlInGaN MQW structures with benefits, such as high crystal quality and small carrier localization degree, compared with the UV-LEDs on sapphire.

  3. Systematic toxicological analysis by high-performance liquid chromatography with diode array detection (HPLC-DAD).

    PubMed

    Pragst, Fritz; Herzler, Matthias; Erxleben, Björn-Thoralf

    2004-01-01

    In recent years, photodiode array detectors (DADs) have been much improved with respect to wavelength accuracy and resolution, sensitivity, linearity and software operation. UV spectra of drugs measured with up-to-date DADs from different manufacturers are in excellent agreement, have the same quality as measured by a conventional UV spectrometer and are highly reproducible. The calculation of similarity parameters by the DAD software includes the entire range of the spectra compared and allows recognition of very small differences. It was shown in a systematic study of more than 2500 toxicologically relevant substances that UV spectra have a very high specificity with respect to substance structure. Therefore, HPLC-DAD in combination with a comprehensive database of UV spectra and retention parameters is one of the most efficient techniques used in systematic toxicological analysis (STA). Furthermore, the method is advantageous for the identification of metabolites, since in many cases they have the same or very similar UV spectra compared with their respective parent substances and their retention times on reversed-phase columns are shifted in a manner typical of the particular biotransformation reaction. Beside these general aspects, practical applications of HPLC-DAD for STA are reviewed with respect to sample preparation and chromatographic conditions. The efficiency of the method is demonstrated for an example of a routine procedure using liquid-liquid extraction with CH 2 Cl 2 and protein precipitation for sample preparation, a system of three isocratic mobile phases with different acetonitrile/phosphate buffer ratios and RP8 columns for chromatography and a database of 2682 UV spectra and relative retention times for substance identification.

  4. Chandra, Extreme Ultraviolet Explorer, and Very Large Array Observations of the Active Binary System σ2 Coronae Borealis

    NASA Astrophysics Data System (ADS)

    Osten, Rachel A.; Ayres, Thomas R.; Brown, Alexander; Linsky, Jeffrey L.; Krishnamurthi, Anita

    2003-01-01

    We present the results of a coordinated observing campaign on the short-period RS CVn binary σ2 Coronae Borealis (F6V+G0V Porb=1.14 days) with the Very Large Array, the Extreme Ultraviolet Explorer, and the Chandra X-Ray Observatory High-Energy Transmission Grating Spectrometer. The radio emission is consistent with previously determined quiescent gyrosynchrotron properties. Multiple flares were seen with Extreme Ultraviolet Explorer, five occurring within two consecutive orbital periods. The first of these flares was observed with Chandra. The Chandra observations of σ2 CrB showed no systematic variations of line fluxes, widths, or Doppler shifts with orbital phase, nor any response in line width or offset due to the flare. This is consistent with both stars being equally active coronal emitters. We have developed a self-consistent method of spectral analysis to derive information from the line and continuum emissions concerning the distribution of plasma with temperature and elemental abundances. A bimodal temperature distribution is appropriate for both quiescent and flare intervals, with a stable peak at 6-8 MK and another variable enhancement at higher temperatures, with evidence for significant contribution from temperatures up to 50 MK during the flare, compared to 30 MK during quiescence. The iron abundance is subsolar during quiescence but is enriched by about a factor of 2 during a large flare seen with Chandra. The noble gas elements neon and argon show elevated abundances with respect to iron, but there is no clear evidence for any first ionization potential-based abundance pattern during quiescence or the flare. We have determined coronal electron densities from the helium-like ions O VII, Ne IX, Mg XI, and Si XIII, which imply densities >=1010 cm-3. There is a small enhancement in the electron densities derived for the flare, but it is not statistically significant. We call attention to electron temperature constraints provided by the ratios of 1s2

  5. Differentiation of Herba Cistanches by fingerprint with high-performance liquid chromatography-diode array detection-mass spectrometry.

    PubMed

    Jiang, Y; Li, S P; Wang, Y T; Chen, X J; Tu, P F

    2009-03-13

    Herba Cistanche (Rou Cong Rong in Chinese), dried succulent stems of Cistanche deserticola or C. tubulosa, is a famous Chinese herbal medicine and has been recorded in the Chinese Pharmacopoeia. In recent years, another two non-official species, C. salsa and C. sinensis have also been used as Herba Cistanche in some regions of China. To investigate the possibility of using these two non-official species as alternatives to the official species, a high-performance liquid chromatography-diode array detection-mass spectrometry (HPLC-DAD-MS) fingerprint method was developed to comparatively analyze the crude herbs of these four species. The fingerprint of C. deserticola, a historically certified species of Herba Cistanche, serves as 'standard pattern' for comparing the similarities with the other species by means of similarity and Principle Component Analysis. Additionally, 18 characteristic peaks in the fingerprints were identified by comparing their retention times, UV spectra and ESI-MS data with those of the reference substances and/or the data in the literatures. The comparative results demonstrate that the fingerprints of C. tubulosa and C. salsa possess high similarity to the standard pattern, suggesting that these two species may be used as alternative species; while that of C. sinensis has low similarity (0.053 correlation coefficient) to the standard pattern, indicating that it cannot be used as the substitute of the official herb. However, the varying fingerprint patterns among the samples of C. deserticola collected from various habitats illustrate that the quality consistency of crude herbs is still a problem worthy of serious concern.

  6. Spectral light measurements in microbenthic phototrophic communities with a fiber-optic microprobe coupled to a sensitive diode array detector

    SciTech Connect

    Kuehl, M. ); Joergensen, B.B. )

    1992-12-01

    A diode array detector system for microscale light measurements with fiber-optic microprobes was developed; it measures intensities of 400-900-nm light over >6 orders of magnitude with a spectral resolution of 2-5 nm. Fiber-optic microprobes to measure field radiance or scalar irradiance were coupled to the detector system and used for spectral light measurements in hypersaline microbial mats and in laminated phototrophic communities of coastal sediments. The vertical distribution of major photopigments of microalgae, cyanobacteria, and anoxygenic phototrophic bacteria could be identified from extinction maxima in measured radiance spectra at 430-550 nm (Chl a and carotenoids), 620-625 nm (phycocyanin), 675 nm (Chl a), 745-750 nm (BChl c), 800-810 nm, and 860-880 nm (BChl a). Scalar irradiance spectra exhibited a different spectral composition and a higher light intensity at the sediment surface as compared to incident light. IR light thus reached 200% of incident at the sediment surface. Maximal light penetration was found for IR light, whereas visible light was strongly attenuated in the upper 0-2 mm of the sediment. Measurements of photon scalar irradiance (400-700 nm) were combined with microelectrode measurements of oxygenic photosynthesis in the coastal sediment. With an incident light intensity of 200 [mu]Einst m[sup [minus]2]s[sup [minus]1], photon scalar irradiance reached a maximum of 283 [mu]Einst m[sup [minus]2]s[sup [minus]1] at the sediment surface. The lower boundary of the euphotic zone was 2.2 mm below the surface at a light intensity of 12 [mu]Einst m[sup [minus]2]s[sup [minus]1]. 20 refs., 6 figs.

  7. Quantification of maltol in Korean ginseng (Panax ginseng) products by high-performance liquid chromatography-diode array detector

    PubMed Central

    Jeong, Hyun Cheol; Hong, Hee-Do; Kim, Young-Chan; Rhee, Young Kyoung; Choi, Sang Yoon; Kim, Kyung-Tack; Kim, Sung Soo; Lee, Young-Chul; Cho, Chang-Won

    2015-01-01

    Background: Maltol, as a type of phenolic compounds, is produced by the browning reaction during the high-temperature treatment of ginseng. Thus, maltol can be used as a marker for the quality control of various ginseng products manufactured by high-temperature treatment including red ginseng. For the quantification of maltol in Korean ginseng products, an effective high-performance liquid chromatography-diode array detector (HPLC-DAD) method was developed. Materials and Methods: The HPLC-DAD method for maltol quantification coupled with a liquid-liquid extraction (LLE) method was developed and validated in terms of linearity, precision, and accuracy. An HPLC separation was performed on a C18 column. Results: The LLE methods and HPLC running conditions for maltol quantification were optimized. The calibration curve of the maltol exhibited good linearity (R2 = 1.00). The limit of detection value of maltol was 0.26 μg/mL, and the limit of quantification value was 0.79 μg/mL. The relative standard deviations (RSDs) of the data of the intra- and inter-day experiments were <1.27% and 0.61%, respectively. The results of the recovery test were 101.35–101.75% with an RSD value of 0.21–1.65%. The developed method was applied successfully to quantify the maltol in three ginseng products manufactured by different methods. Conclusion: The results of validation demonstrated that the proposed HPLC-DAD method was useful for the quantification of maltol in various ginseng products. PMID:26246746

  8. Determination of pesticides in sunflower seeds by high-performance liquid chromatography coupled with a diode array detector.

    PubMed

    Tuzimski, Tomasz; Rejczak, Tomasz

    2014-01-01

    The application of RP-HPLC with a diode array detector for identification and quantitative analysis of pesticides in sunflower seed samples is demonstrated. An HPLC procedure on C18 RP column has been developed for analysis of selected pesticides from different chemical groups: simazine, isoproturon, terbuthylazine, linuron, captan, terbutryn, procymidone, fenitrothion, clofentezine, and bromopropylate. We investigated the possibility of expanding the scope of the four analyte extraction procedures for isolation of pesticides from plant matrixes with high levels of lipids. The following procedures were tested: A, ultrasound-assisted solvent extraction (UAE) and SPE; B, dispersive-SPE (d-SPE); C, UAE and d-SPE; and D, UAE/SPE/d-SPE. Average recoveries from spiked samples at different concentrations in the range from 0.1 to 1.40 microg/g in the plant materials and the SDs for C18 cartridges and solvents by the proposed RP-HPLC-DAD method after the extraction procedures are also presented. The efficiency of procedures A-D was evaluated using real food samples from Hungary, Bulgaria, and Poland. The quantity of terbuthylazine determined was in the range of 7.1-12.7 ng/g (n = 6), whereas the quantity of procymidone determined was in the range of 3.7-5.7 ng/g (n = 3) in plant materials. The quantities of pesticides determined in sunflower seeds were below the maximum residue levels (excluding captan) established in the European Union legislation. The method was validated for precision and accuracy.

  9. Determination of nifedipine in serum of women in preterm labor by high-performance liquid chromatography with diode array detection.

    PubMed

    Kowalczuk, Dorota; Wawrzycka, Maria Bozena; Haratym Maj, Agnieszka

    2006-01-01

    Nifedipine (Nif) is widely used in treating cardiovascular disorders (especially hypertension) and for inhibiting preterm labor. A fully validated selective high-performance liquid chromatographic method with diode array detection, using solid-phase extraction, was developed for the determination of Nif in human serum. To assess specificity, Nif and its degradation products were separated on a Purospher RP-18 (5 microm, 125 x 4 mm) column plus a LiChrospher 100 RP-18 (5 microm, 4 x 4 mm) precolumn with a mobile phase of methanol-10 mM aqueous trifluoroacetic acid, pH 7.3 (57 + 43, v/v); chromatographic separation was followed by UV detection at 238 nm. For toxicological analysis, Nif in the presence of other calcium-channel antagonist drugs was identified under optimum chromatographic conditions. The calibration graph was constructed over the concentration range of 12.5-400 ng/mL in serum with good correlation (r = 0.9956). This method was not subject to interference by other plasma components and was successfully applied to the assay of Nif in spiked human serum and in serum of women in preterm labor after sublingual administration of 30 mg Nif per day divided into 3 equal doses. The mean recovery based on the ratio of the slopes of serum and mobile phase standard curves was 96.5%. The detection and quantification limits of the drug in spiked human serum were found to be 6 and 17.5 ng/mL, respectively. Validation of the method demonstrated good intraday and interday precision, which ranged from 2.18 to 6.67% and from 6.52 to 11.93%, respectively.

  10. Screening of Carotenoids in Tomato Fruits by Using Liquid Chromatography with Diode Array-Linear Ion Trap Mass Spectrometry Detection.

    PubMed

    Gentili, Alessandra; Caretti, Fulvia; Ventura, Salvatore; Pérez-Fernández, Virginia; Venditti, Alessandro; Curini, Roberta

    2015-08-26

    This paper presents an analytical strategy for a large-scale screening of carotenoids in tomato fruits by exploiting the potentialities of the triple quadrupole-linear ion trap hybrid mass spectrometer (QqQLIT). The method involves separation on C30 reversed-phase column and identification by means of diode array detection (DAD) and atmospheric pressure chemical ionization-mass spectrometry (APCI-MS). The authentic standards of six model compounds were used to optimize the separative conditions and to predict the chromatographic behavior of untargeted carotenoids. An information dependent acquisition (IDA) was performed with (i) enhanced-mass scan (EMS) as the survey scan, (ii) enhanced-resolution (ER) scan to obtain the exact mass of the precursor ions (16-35 ppm), and (iii) enhanced product ion (EPI) scan as dependent scan to obtain structural information. LC-DAD-multiple reaction monitoring (MRM) chromatograms were also acquired for the identification of targeted carotenoids occurring at low concentrations; for the first time, the relative abundance between the MRM transitions (ion ratio) was used as an extra tool for the MS distinction of structural isomers and the related families of geometrical isomers. The whole analytical strategy was high-throughput, because a great number of experimental data could be acquired with few analytical steps, and cost-effective, because only few standards were used; when applied to characterize some tomato varieties ('Tangerine', 'Pachino', 'Datterino', and 'Camone') and passata of 'San Marzano' tomatoes, our method succeeded in identifying up to 44 carotenoids in the 'Tangerine'" variety.

  11. Analysis of anticoagulant rodenticide residues in Microtus arvalis tissues by liquid chromatography with diode array, fluorescence and mass spectrometry detection.

    PubMed

    Hernández, Alma M; Bernal, José; Bernal, José L; Martín, María T; Caminero, Constantino; Nozal, María J

    2013-04-15

    We describe here a fast and selective analytical method to determine the levels of four anticoagulant rodenticides (chlorophacinone, bromadiolone, brodifacoum and difenacoum) in animal tissues by liquid chromatography (LC) using different detection methods: fluorescence (FLD), diode array (DAD) and electrospray ionization-mass spectrometry (ESI-MS). Rodenticides were extracted from freeze-dried and homogenized tissue samples (liver, intestine and muscle) that had been obtained from the common vole (Microtus arvalis). These samples were diluted in 5 mL of methanol, the solution was shaken and centrifuged, and the supernatant was removed and evaporated to dryness. The residue was reconstituted in 1 mL of methanol (liver samples) or 1 mL of the mobile phase (muscle and intestine samples), and injected onto an LC-DAD-FLD-MS system coupled to electrospray ionization (ESI) in negative mode. After conducting an LC optimization study, we selected a Gemini 5 μm C18 column, a mobile phase composed of a mixture of 30 mM ammonium formate in water and methanol (26:74, v/v), and we used an isocratic elution mode. The method was fully validated and shown to be selective, precise, accurate, and linear in the range from ~5μg/kg (ESI-MS) or ~50 μg/kg (DAD-FLD) to 10,000 μg/kg, depending on the compound analyzed. Recoveries ranged from 82% to 103%, while the limits of detection and quantification ranged from 9-89 μg/kg (FLD-DAD) and 0.6-4.6 μg/kg (ESI-MS). This method was successfully used to simultaneously measure the aforementioned compounds in M. arvalis tissues.

  12. New background correction method for liquid chromatography with diode array detection, infrared spectroscopic detection and Raman spectroscopic detection.

    PubMed

    Boelens, Hans F M; Dijkstra, Reyer J; Eilers, Paul H C; Fitzpatrick, Fiona; Westerhuis, Johan A

    2004-11-19

    A new method to eliminate the background spectrum (EBS) during analyte elution in column liquid chromatography (LC) coupled to spectroscopic techniques is proposed. This method takes into account the shape and also intensity differences of the background eluent spectrum. This allows the EBS method to make a better estimation of the background eluent spectrum during analyte elution. This is an advantage for quantification as well as for identification of analytes. The EBS method uses a two-step procedure. First, the baseline spectra are modeled using a limited number of principal components (PCs). Subsequently, an asymmetric least squares (asLS) regression method is applied using these principal components to correct the measured spectra during elution for the background contribution. The asymmetric least squares regression needs one parameter, the asymmetry factor p. This asymmetry factor determines relative weight of positive and negative residuals. Simulations are performed to test the EBS method in well-defined situations. The effect of spectral noise on the performance and the sensitivity of the EBS method for the value of the asymmetry factorp is tested. Two applications of the EBS method are discussed. In the first application, the goal is to extract the analyte spectrum from an LC-Raman analysis. In this case, the EBS method facilitates easy identification of unknown analytes using spectral libraries. In a second application, the EBS method is used for baseline correction in LC-diode array detection (DAD) analysis of polymeric standards during a gradient elution separation. It is shown that the EBS method yields a good baseline correction, without the need to perform a blank chromatographic run.

  13. Rapid separation and identification of furocoumarins in Angelica dahurica by high-performance liquid chromatography with diode-array detection, time-of-flight mass spectrometry and quadrupole ion trap mass spectrometry.

    PubMed

    Zhang, Hai; Gong, Chungui; Lv, Lei; Xu, Yuanjie; Zhao, Liang; Zhu, Zhenyu; Chai, Yifeng; Zhang, Guoqing

    2009-07-01

    High-performance liquid chromatography with diode-array detection (HPLC/DAD), time-of-flight mass spectrometry (HPLC/TOFMS) and quadrupole ion trap mass spectrometry (HPLC/QITMS) were used for separation, identification and structural analysis of furocoumarins in Angelica dahurica. Two furocoumarins (imperatorin and isoimperatorin) in Angelica dahurica extract were identified unambiguously by comparing their relative retention times, characteristic ultraviolet information and accurate mass measurement. A formula database of known furocoumarins in Angelica dahurica was established, against which the other 21 furocoumarins were identified effectively based on the accurate extract masses and formulae acquired by HPLC/TOFMS. In order to distinguish the isomers, multi-stage mass spectrometry (MSn, ion trap mass spectrometry) was used. General fragmentation behavior of the furocoumarins in the ion trap mass spectrometer was studied by the two furocoumarin standards, and their fragmentation rules in MS(n) spectra were summarized. These deduced fragmentation rules of furocoumarins were successfully implemented in distinguishing the three groups of isomers in Angelica dahurica by HPLC/QITMS. By using the three different analytical techniques, 23 furocoumarins in Angelica dahurica were tentatively identified within 30 min. Finally, HPLC/TOFMS fingerprints of Angelica dahurica were established by which it can be concluded that a rapid and effective method based on the three analytical techniques for identification of chemical components was established. This can provide help for further quality control of Angelica dahurica and pharmacology mechanism study of furocoumarins in Angelica dahurica.

  14. Video-rate fluorescence lifetime imaging camera with CMOS single-photon avalanche diode arrays and high-speed imaging algorithm.

    PubMed

    Li, David D-U; Arlt, Jochen; Tyndall, David; Walker, Richard; Richardson, Justin; Stoppa, David; Charbon, Edoardo; Henderson, Robert K

    2011-09-01

    A high-speed and hardware-only algorithm using a center of mass method has been proposed for single-detector fluorescence lifetime sensing applications. This algorithm is now implemented on a field programmable gate array to provide fast lifetime estimates from a 32 × 32 low dark count 0.13 μm complementary metal-oxide-semiconductor single-photon avalanche diode (SPAD) plus time-to-digital converter array. A simple look-up table is included to enhance the lifetime resolvability range and photon economics, making it comparable to the commonly used least-square method and maximum-likelihood estimation based software. To demonstrate its performance, a widefield microscope was adapted to accommodate the SPAD array and image different test samples. Fluorescence lifetime imaging microscopy on fluorescent beads in Rhodamine 6G at a frame rate of 50 fps is also shown.

  15. Room-temperature, continuous-wave, 946-nm Nd:YAG laser pumped by laser-diode arrays and intracavity frequency doubling to 473 nm

    SciTech Connect

    Risk, W.P.; Lenth, W.

    1987-12-01

    We report the use of GaAlAs laser-diode arrays to pump a cw Nd:YAG laser operating on the 946-nm /sup 4/F/sub 3/2/..-->../sup 4/I/sub 9/2/ transition. At room temperature, the lasing threshold was reached with 58 mW of absorbed pump power, and, with 175 mW of absorbed pump power, 42 mW of output power at 946 nm was obtained in a TEM/sub 00/ mode by using 0.7% output coupling. In addition, pumping with an infrared dye laser operating in a pure TEM/sub 00/ mode was used to investigate the effects of reabsorption loss that are characteristic of the 946-nm laser transition. LiIO/sub 3/ was used as an intracavity doubling crystal, and 100 ..mu..W of blue light was generated by using diode-laser pumping in a nonoptimized cavity.

  16. Laser Diode Ignition (LDI)

    NASA Technical Reports Server (NTRS)

    Kass, William J.; Andrews, Larry A.; Boney, Craig M.; Chow, Weng W.; Clements, James W.; Merson, John A.; Salas, F. Jim; Williams, Randy J.; Hinkle, Lane R.

    1994-01-01

    This paper reviews the status of the Laser Diode Ignition (LDI) program at Sandia National Labs. One watt laser diodes have been characterized for use with a single explosive actuator. Extensive measurements of the effect of electrostatic discharge (ESD) pulses on the laser diode optical output have been made. Characterization of optical fiber and connectors over temperature has been done. Multiple laser diodes have been packaged to ignite multiple explosive devices and an eight element laser diode array has been recently tested by igniting eight explosive devices at predetermined 100 ms intervals.

  17. Illumination distribution and signal transmission for indoor visible light communication with different light-emitting diode arrays and pre-equality circuits

    NASA Astrophysics Data System (ADS)

    Chen, Hsi-Chao; Liou, Cheng-Jyun; Siao, Syuan-Ruei

    2015-11-01

    The purpose of this study was to seek the optimal design for light-emitting diode (LED) arrays and pre-equality circuits in indoor visible lighting illumination combined with communication. The optical and communicational properties of illumination distribution and signal transmission were investigated. These illumination distributions of array sources were derivate and simulated and actually can be used in free-space communication. Simulated results show the total flux size was rectangle>radial>circlearray, and real measurements also showed the total flux was rectangle>radial>circlearray. The simulated and measured results have a similarity of over 98% by normalized cross correlation. In addition, when the distance of the installed lamp from the wall was 1 m, the rectangular array had the best illumination uniformity of 77.24%, and the size of uniformity was the rectangle>radial≈circle array. Finally, the gain and constant-current pre-equality circuits were used in free-space communication with a carrier frequency from 1 KHz to 1 MHz at a distance of 1.8 m. Both the received signal intensity and divergence angle were rectangle>radial>circle array. The constant-current pre-equality circuit could add the divergence angle from ±18.6 deg to ±36.68 deg in the rectangle array at a carrier frequency of 1 MHz.

  18. Impact of Mixture Gas Plasma of N2 and O2 as the N Source on ZnO-Based Ultraviolet Light-Emitting Diodes Fabricated by Molecular Beam Epitaxy

    NASA Astrophysics Data System (ADS)

    Kato, Hiroyuki; Yamamuro, Tomofumi; Ogawa, Akio; Kyotani, Chizu; Sano, Michihiro

    2011-09-01

    ZnO-based double-heterostructure ultraviolet light-emitting diodes (LEDs) were fabricated on n-type Zn-polar ZnO substrates by plasma-assisted molecular beam epitaxy employing mixture gas plasma of N2 and O2 as the N source. By using mixture gas plasma of N2 with a little added O2, the number of N atoms increased and N2 molecules decreased, as confirmed by optical emission spectrometry. The fabricated LEDs had an ultraviolet near-band-emission of around 380 nm. The integrated electroluminescence intensity of the LED fabricated using N2 and O2 plasma was more than 10 times higher than that of an LED fabricated using N2 plasma.

  19. Optimizing the accuracy of a helical diode array dosimeter: A comprehensive calibration methodology coupled with a novel virtual inclinometer

    SciTech Connect

    Kozelka, Jakub; Robinson, Joshua; Nelms, Benjamin; Zhang, Geoffrey; Savitskij, Dennis; Feygelman, Vladimir

    2011-09-15

    Purpose: The goal of any dosimeter is to be as accurate as possible when measuring absolute dose to compare with calculated dose. This limits the uncertainties associated with the dosimeter itself and allows the task of dose QA to focus on detecting errors in the treatment planning (TPS) and/or delivery systems. This work introduces enhancements to the measurement accuracy of a 3D dosimeter comprised of a helical plane of diodes in a volumetric phantom. Methods: We describe the methods and derivations of new corrections that account for repetition rate dependence, intrinsic relative sensitivity per diode, field size dependence based on the dynamic field size determination, and positional correction. Required and described is an accurate ''virtual inclinometer'' algorithm. The system allows for calibrating the array directly against an ion chamber signal collected with high angular resolution. These enhancements are quantitatively validated using several strategies including ion chamber measurements taken using a ''blank'' plastic shell mimicking the actual phantom, and comparison to high resolution dose calculations for a variety of fields: static, simple arcs, and VMAT. A number of sophisticated treatment planning algorithms were benchmarked against ion chamber measurements for their ability to handle a large air cavity in the phantom. Results: Each calibration correction is quantified and presented vs its independent variable(s). The virtual inclinometer is validated by direct comparison to the gantry angle vs time data from machine log files. The effects of the calibration are quantified and improvements are seen in the dose agreement with the ion chamber reference measurements and with the TPS calculations. These improved agreements are a result of removing prior limitations and assumptions in the calibration methodology. Average gamma analysis passing rates for VMAT plans based on the AAPM TG-119 report are 98.4 and 93.3% for the 3%/3 mm and 2%/2 mm dose

  20. SU-E-T-375: Evaluation of a MapCHECK2(tm) Planar 2-D Diode Array for High-Dose-Rate Brachytherapy Treatment Delivery Verifications

    SciTech Connect

    Macey, N; Siebert, M; Shvydka, D; Parsai, E

    2015-06-15

    Purpose: Despite improvements of HDR brachytherapy delivery systems, verification of source position is still typically based on the length of the wire reeled out relative to the parked position. Yet, the majority of errors leading to medical events in HDR treatments continue to be classified as missed targets or wrong treatment sites. We investigate the feasibility of using dose maps acquired with a two-dimensional diode array to independently verify the source locations, dwell times, and dose during an HDR treatment. Methods: Custom correction factors were integrated into frame-by-frame raw counts recorded for a Varian VariSource™ HDR afterloader Ir-192 source located at various distances in air and in solid water from a MapCHECK2™ diode array. The resultant corrected counts were analyzed to determine the dwell position locations and doses delivered. The local maxima of polynomial equations fitted to the extracted dwell dose profiles provided the X and Y coordinates while the distance to the source was determined from evaluation of the full width at half maximum (FWHM). To verify the approach, the experiment was repeated as the source was moved through dwell positions at various distances along an inclined plane, mimicking a vaginal cylinder treatment. Results: Dose map analysis was utilized to provide the coordinates of the source and dose delivered over each dwell position. The accuracy in determining source dwell positions was found to be +/−1.0 mm of the preset values, and doses within +/−3% of those calculated by the BrachyVision™ treatment planning system for all measured distances. Conclusion: Frame-by-frame data furnished by a 2 -D diode array can be used to verify the dwell positions and doses delivered by the HDR source over the course of treatment. Our studies have verified that measurements provided by the MapCHECK2™ can be used as a routine QA tool for HDR treatment delivery verification.

  1. Comparative study of fourteen alkaloids from Uncaria rhynchophylla hooks and leaves using HPLC-diode array detection-atmospheric pressure chemical ionization/MS method.

    PubMed

    Qu, Jialin; Gong, Tianxing; Ma, Bin; Zhang, Lin; Kano, Yoshihiro; Yuan, Dan

    2012-01-01

    The purpose of the study is to compare alkaloid profile of Uncaria rhynchophylla hooks and leaves. Ten oxindole alkaloids and four glycosidic indole alkaloids were identified using HPLC-diode array detection (DAD) or LC-atmospheric pressure chemical ionization (APCI)-MS method, and a HPLC-UV method for simultaneous quantification of major alkaloids was validated. The hooks are characterized by high levels of four oxindole alkaloids rhynchophylline (R), isorhynchophylline (IR), corynoxeine (C) and isocorynoxeine (IC), while the leaves contained high level of two glycosidic indole alkaloids vincoside lactam (VL) and strictosidine (S). The presented methods have proven its usefulness in chemical characterization of U. rhynchophylla hooks and leaves.

  2. Simultaneous determination of seven azole antifungal drugs in serum by ultra-high pressure liquid chromatography and diode array detection.

    PubMed

    Mistretta, V; Dubois, N; Denooz, R; Charlier, C

    2014-01-01

    Azole antifungals are a group of fungistatic agents that can be administered orally or parenterally. The determination of the concentrations of these antifungals (miconazole, fluconazole, ketoconazole, posaconazole, voriconazole, itraconazole, and its major active metabolite, hydroxy-itraconazole) in serum can be useful to adapt the doses to pharmacological ranges because of large variability in the absorption and metabolism of the drugs, multiple drug interactions, but also potential resistance or toxicity. A method was developed and validated for the simultaneous determination of these drugs in serum utilizing ultra-high pressure liquid chromatography and diode array detection (UHPLC-DAD). After a simple and rapid liquid-liquid extraction, the pre-treated sample was analysed on an UHPLC-DAD system (Waters Corporation(®)). The chromatographic separation was carried out on an Acquity BEH C18 column (Waters Corporation) with a gradient mode of mobile phase composed of acetonitrile and aqueous ammonium bicarbonate 10·0 M pH10. The flow rate was 0·4 ml/min and the injection volume was 5 μl. The identification wavelength varied according to the drug from 210 to 260 nm. The method was validated by the total error method approach by using an analytical validation software (e•noval V3·0 Arlenda(®)). The seven azole antifungals were identified by retention time and specific UV spectra, over a 13-minute run time. All calibration curves showed good linearity (r(2)>0·99) in ranges considered clinically adequate. The assay was linear from 0·05 to 10 mg/l for voriconazole, posaconazole, itraconazole, hydroxy-itraconazole, and ketoconazole, from 0·3 to 10 mg/l for fluconazole, and from 0·1 to 10 mg/l for miconazole. The bias and imprecision values for intra- and inter-assays were lower than 10% and than 15%, respectively. In conclusion, a simple, sensitive, and selective UHPLC-DAD method was developed and validated to determine seven azole antifungal drugs in human

  3. Ultraviolet Extensions

    NASA Technical Reports Server (NTRS)

    2008-01-01

    time. In fact, it is one of the 'deepest,' or longest-exposure, images of a nearby galaxy in ultraviolet light. This deeper view shows more clusters of stars, as well as stars in the very remote reaches of the galaxy, up to 140,000 light-years away from its core.

    The view at the left is a combination of the ultraviolet picture at the right and data taken by the telescopes of the National Science Foundation's Very Large Array in New Mexico. The radio data, colored here in red, reveal extended galactic arms of gaseous hydrogen atoms, which are raw ingredients for stars. Astronomers are excited that the remote clusters of baby stars match up with the extended arms, because this helps them better understand how stars can be created out in the boondocks of a galaxy.

    M83 is located 15 million light-years away in the southern constellation Hydra.

    In the Galaxy Evolution Explorer image on the right, near-ultraviolet light (or longer-wavelength ultraviolet light) is colored yellow and far-ultraviolet light is blue. In the combined image at the left, far-ultraviolet light is blue, near-ultraviolet light is green, and the radio emission at a wavelength of 21 centimeters is red.

  4. Low-noise low-jitter 32-pixels CMOS single-photon avalanche diodes array for single-photon counting from 300 nm to 900 nm

    SciTech Connect

    Scarcella, Carmelo; Tosi, Alberto Villa, Federica; Tisa, Simone; Zappa, Franco

    2013-12-15

    We developed a single-photon counting multichannel detection system, based on a monolithic linear array of 32 CMOS SPADs (Complementary Metal-Oxide-Semiconductor Single-Photon Avalanche Diodes). All channels achieve a timing resolution of 100 ps (full-width at half maximum) and a photon detection efficiency of 50% at 400 nm. Dark count rate is very low even at room temperature, being about 125 counts/s for 50 μm active area diameter SPADs. Detection performance and microelectronic compactness of this CMOS SPAD array make it the best candidate for ultra-compact time-resolved spectrometers with single-photon sensitivity from 300 nm to 900 nm.

  5. Latest developments of 10μm pitch HgCdTe diode array from the legacy to the extrinsic technology

    NASA Astrophysics Data System (ADS)

    Péré-Laperne, Nicolas; Berthoz, Jocelyn; Taalat, Rachid; Rubaldo, Laurent; Kerlain, Alexandre; Carrère, Emmanuel; Dargent, Loïc.

    2016-05-01

    Sofradir recently presented Daphnis, its latest 10 μm pitch product family. Both Daphnis XGA and HD720 are 10μm pitch mid-wave infrared focal plane array. Development of small pixel pitch is opening the way to very compact products with a high spatial resolution. This new product is taking part in the HOT technology competition allowing reductions in size, weight and power of the overall package. This paper presents the recent developments achieved at Sofradir to make the 10μm pitch HgCdTe focal plane array based on the legacy technology. Electrical and electro-optical characterizations are presented to define the appropriate design of 10μm pitch diode array. The technological tradeoffs are explained to lower the dark current, to keep high quantum efficiency with a high operability above 110K, F/4. Also, Sofradir recently achieved outstanding Modulation Transfer Function (MTF) demonstration at this pixel pitch, which clearly demonstrates the benefit to users of adopting 10μm pixel pitch focal plane array based detectors. Furthermore, the HgCdTe technology has demonstrated an increase of the operating temperature, plus 40K, moving from the legacy to the P-on-n one at a 15μm pitch in mid-wave band. The first realizations using the extrinsic P-on-n technology and the characterizations of diodes with a 10μm pitch neighborhood will be presented in both mid-wave and long-wave bands.

  6. Macroscopic Violation of Three Cauchy-Schwarz Inequalities Using Correlated Light Beams From an Infra-Red Emitting Semiconductor Diode Array

    NASA Technical Reports Server (NTRS)

    Edwards, P. J.; Huang, X.; Li, Y. Q. (Editor); Wang, Y. Z. (Editor)

    1996-01-01

    We briefly review quantum mechanical and semi-classical descriptions of experiments which demonstrate the macroscopic violation of the three Cauchy-Schwarz inequalities: g(sup 2)(sub 11)(0) greater than or equal to 1; g(sup 2)(sub 11)(0) greater than or equal to g(sup 2)(sub 11)(t), (t approaches infinity); (the absolute value of g(sup 2)(sub 11)(0))(exp 2) less than or equal to g(sup 2)(sub 11)(0) g(sup 2)(sub 11)(0). Our measurements demonstrate the violation, at macroscopic intensities, of each of these inequalities. We show that their violation, although weak, can be demonstrated through photodetector current covariance measurements on correlated sub-Poissonian Poissonian, and super Poissonian light beams. Such beams are readily generated by a tandem array of infrared-emitting semiconductor junction diodes. Our measurements utilize an electrically coupled array of one or more infrared-emitting diodes, optically coupled to a detector array. The emitting array is operated in such a way as to generate highly correlated beams of variable photon Fano Factor. Because the measurements are made on time scales long compared with the first order coherence time and with detector areas large compared with the corresponding coherence areas, first order interference effects are negligible. The first and second inequalities are violated, as expected, when a sub-Poissonian light beam is split and the intensity fluctuations of the two split beams are measured by two photodetectors and subsequently cross-correlated. The third inequality is violated by bunched (as well as anti-bunched) beams of equal intensity provided the measured cross correlation coefficient exceeds (F - 1)/F, where F is the measured Fano Factor of each beam. We also investigate the violation for the case of unequal beams.

  7. High-performance GaSb laser diodes and diode arrays in the 2.1-3.3 micron wavelength range for sensing and defense applications

    NASA Astrophysics Data System (ADS)

    Dvinelis, Edgaras; TrinkÅ«nas, Augustinas; Greibus, Mindaugas; Kaušylas, Mindaugas; Žukauskas, Tomas; Å imonytÄ--, Ieva; Songaila, RamÅ«nas; Vizbaras, Augustinas; Vizbaras, Kristijonas

    2015-01-01

    Mid-infrared spectral region (2-4 μm) is gaining significant attention recently due to the presence of numerous enabling applications in the field of gas sensing, medical, and defense applications. Gas sensing in this spectral region is attractive due to the presence of numerous absorption lines for such gases as methane, ethane, ozone, carbon dioxide, carbon monoxide, etc. Sensing of the mentioned gas species is of particular importance for applications such as atmospheric LIDAR, petrochemical industry, greenhouse gas monitoring, etc. Defense applications benefit from the presence of covert atmospheric transmission window in the 2.1-2.3 micron band which is more eye-safe and offers less Rayleigh scattering than the conventional atmospheric windows in the near-infrared. Major requirement to enable these application is the availability of high-performance, continuous-wave laser sources in this window. Type-I GaSb-based laser diodes are ideal candidates for these applications as they offer direct emission possibility, high-gain and continuous wave operation. Moreover, due to the nature of type-I transition, these devices have a characteristic low operation voltage, which results in very low input powers and high wall-plug efficiency. In this work, we present recent results of 2 μm - 3.0 μm wavelength room-temperature CW light sources based on type-I GaSb developed at Brolis Semiconductors. We discuss performance of defense oriented high-power multimode laser diodes with < 1 W CW power output with over 30 % WPE as well as ~ 100 mW single TE00 Fabry-Perot chips. In addition, recent development efforts on sensing oriented broad gain superluminescent gain chips will be presented.

  8. Classification of the medicinal plants of the genus Atractylodes using high-performance liquid chromatography with diode array and tandem mass spectrometry detection combined with multivariate statistical analysis.

    PubMed

    Cho, Hyun-Deok; Kim, Unyong; Suh, Joon Hyuk; Eom, Han Young; Kim, Junghyun; Lee, Seul Gi; Choi, Yong Seok; Han, Sang Beom

    2016-04-01

    Analytical methods using high-performance liquid chromatography with diode array and tandem mass spectrometry detection were developed for the discrimination of the rhizomes of four Atractylodes medicinal plants: A. japonica, A. macrocephala, A. chinensis, and A. lancea. A quantitative study was performed, selecting five bioactive components, including atractylenolide I, II, III, eudesma-4(14),7(11)-dien-8-one and atractylodin, on twenty-six Atractylodes samples of various origins. Sample extraction was optimized to sonication with 80% methanol for 40 min at room temperature. High-performance liquid chromatography with diode array detection was established using a C18 column with a water/acetonitrile gradient system at a flow rate of 1.0 mL/min, and the detection wavelength was set at 236 nm. Liquid chromatography with tandem mass spectrometry was applied to certify the reliability of the quantitative results. The developed methods were validated by ensuring specificity, linearity, limit of quantification, accuracy, precision, recovery, robustness, and stability. Results showed that cangzhu contained higher amounts of atractylenolide I and atractylodin than baizhu, and especially atractylodin contents showed the greatest variation between baizhu and cangzhu. Multivariate statistical analysis, such as principal component analysis and hierarchical cluster analysis, were also employed for further classification of the Atractylodes plants. The established method was suitable for quality control of the Atractylodes plants.

  9. Quality assessment of crude and processed ginger by high-performance liquid chromatography with diode array detection and mass spectrometry combined with chemometrics.

    PubMed

    Deng, Xianmei; Yu, Jiangyong; Zhao, Ming; Zhao, Bin; Xue, Xingyang; Che, ChunTao; Meng, Jiang; Wang, Shumei

    2015-09-01

    A sensitive, simple, and validated high-performance liquid chromatography with diode array detection and mass spectrometry detection method was developed for three ginger-based traditional Chinese herbal drugs, Zingiberis Rhizoma, Zingiberis Rhizome Preparatum, and Zingiberis Rhizome Carbonisata. Chemometrics methods, such as principal component analysis, hierarchical cluster analysis, and analysis of variance, were also employed in the data analysis. The results clearly revealed significant differences among Zingiberis Rhizoma, Zingiberis Rhizome Preparatum, and Zingiberis Rhizome Carbonisata, indicating variations in their chemical compositions during the processing, which may elucidate the relationship of the thermal treatment with the change of the constituents and interpret their different clinical uses. Furthermore, the sample consistency of Zingiberis Rhizoma, Zingiberis Rhizome Preparatum, and Zingiberis Rhizome Carbonisata can also be visualized by high-performance liquid chromatography with diode array detection and mass spectrometry analysis followed by principal component analysis/hierarchical cluster analysis. The comprehensive strategy of liquid chromatography with mass spectrometry analysis coupled with chemometrics should be useful in quality assurance for ginger-based herbal drugs and other herbal medicines.

  10. Liquid chromatography with diode array detection combined with spectral deconvolution for the analysis of some diterpene esters in Arabica coffee brew.

    PubMed

    Erny, Guillaume L; Moeenfard, Marzieh; Alves, Arminda

    2015-02-01

    In this manuscript, the separation of kahweol and cafestol esters from Arabica coffee brews was investigated using liquid chromatography with a diode array detector. When detected in conjunction, cafestol, and kahweol esters were eluted together, but, after optimization, the kahweol esters could be selectively detected by setting the wavelength at 290 nm to allow their quantification. Such an approach was not possible for the cafestol esters, and spectral deconvolution was used to obtain deconvoluted chromatograms. In each of those chromatograms, the four esters were baseline separated allowing for the quantification of the eight targeted compounds. Because kahweol esters could be quantified either using the chromatogram obtained by setting the wavelength at 290 nm or using the deconvoluted chromatogram, those compounds were used to compare the analytical performances. Slightly better limits of detection were obtained using the deconvoluted chromatogram. Identical concentrations were found in a real sample with both approaches. The peak areas in the deconvoluted chromatograms were repeatable (intraday repeatability of 0.8%, interday repeatability of 1.0%). This work demonstrates the accuracy of spectral deconvolution when using liquid chromatography to mathematically separate coeluting compounds using the full spectra recorded by a diode array detector.

  11. Quality evaluation of Radix Stemonae through simultaneous quantification of bioactive alkaloids by high-performance liquid chromatography coupled with diode array and evaporative light scattering detectors.

    PubMed

    Li, Song-Lin; Jiang, Ren-Wang; Hon, Po-Ming; Cheng, Ling; Xu, Hong-Xi; Greger, Harald; But, Paul Pui-Hay; Shaw, Pang-Chui

    2007-10-01

    A high-performance liquid chromatography coupled with diode array detection and evaporative light scattering detection (HPLC-DAD-ELSD) method was developed to simultaneously quantify six major bioactive alkaloids belonging to different structure types in Radix Stemonae, Bai-Bu in Chinese, a traditionally used antitussive and insecticidal medicinal material in China and other countries of Southeast Asia. Diode array detector (DAD) with the wavelengths at 307 and 260 nm was used to monitor the conjugated system of protostemonine (2) and maistemonine (4), respectively, whereas evaporative light scattering detector (ELSD) was employed to detect croomine (1), stemoninine (3), neotuberostemonine (5) and tuberostemonine (6), the other four analytes with no or poor chromophores. The assay was validated to be sensitive, precise and accurate, with a detection limit of 3.64-0.04 microg/mL depending on the individual analytes. The overall intra- and inter-day variations were less than 9.3%, and the overall recoveries higher than 91.2%, respectively. The correlation coefficients of the calibration curves were better than 0.996 for all analytes. The newly established method was successfully utilized to determine six major components in the genuine sources of Radix Stemonae: Stemona japonica, S. sessilifolia and S. tuberosa. Significant variations of contents of these components were demonstrated in samples of these three species. This simple, rapid, low-cost and reliable method is suitable for the routine quality control of herbal medicines containing bioactive components with different structure types such as Radix Stemonae.

  12. Integrating qualitative and quantitative characterization of traditional Chinese medicine injection by high-performance liquid chromatography with diode array detection and tandem mass spectrometry.

    PubMed

    Xie, Yuan-yuan; Xiao, Xue; Luo, Juan-min; Fu, Chan; Wang, Qiao-wei; Wang, Yi-ming; Liang, Qiong-lin; Luo, Guo-an

    2014-06-01

    The present study aims to describe and exemplify an integrated strategy of the combination of qualitative and quantitative characterization of a multicomponent mixture for the quality control of traditional Chinese medicine injections with the example of Danhong injection (DHI). The standardized chemical profile of DHI has been established based on liquid chromatography with diode array detection. High-performance liquid chromatography coupled with time-of-flight mass spectrometry and high-performance liquid chromatography with electrospray multistage tandem ion-trap mass spectrometry have been developed to identify the major constituents in DHI. The structures of 26 compounds including nucleotides, phenolic acids, and flavonoid glycosides were identified or tentatively characterized. Meanwhile, the simultaneous determination of seven marker constituents, including uridine, adenosine, danshensu, protocatechuic aldehyde, p-coumaric acid, rosmarinic acid, and salvianolic acid B, in DHI was performed by multiwavelength detection based on high-performance liquid chromatography with diode array detection. The integrated qualitative and quantitative characterization strategy provided an effective and reliable pattern for the comprehensive and systematic characterization of the complex traditional Chinese medicine system.

  13. Determination of Phenolic Content in Different Barley Varieties and Corresponding Malts by Liquid Chromatography-diode Array Detection-Electrospray Ionization Tandem Mass Spectrometry

    PubMed Central

    Carvalho, Daniel O.; Curto, Andreia F.; Guido, Luís F.

    2015-01-01

    A simple and reliable method for the simultaneous determination of nine phenolic compounds in barley and malted barley was established, using liquid chromatography-diode array detection-electrospray ionization tandem mass spectrometry (HPLC-DAD-ESI-MS/MS). The phenolic compounds can be easily detected with both systems, despite significant differences in sensitivity. Concentrations approximately 180-fold lower could be achieved by mass spectrometry analysis compared to diode array detection, especially for the flavan-3-ols (+)-catechin and (−)-epicatechin, which have poor absorptivity in the UV region. Malt samples were characterized by higher phenolic content comparing to corresponding barley varieties, revealing a significant increase of the levels of (+)-catechin and (−)-epicatechin during the malting process. Moreover, the industrial malting is responsible for modification on the phenolic profile from barley to malt, namely on the synthesis or release of sinapinic acid and epicatechin. Accordingly, the selection of the malting parameters, as well as the barley variety plays an important role when considering the quality and antioxidant stability of beer. PMID:26783844

  14. Flexible Light Emission Diode Arrays Made of Transferred Si Microwires-ZnO Nanofilm with Piezo-Phototronic Effect Enhanced Lighting.

    PubMed

    Li, Xiaoyi; Liang, Renrong; Tao, Juan; Peng, Zhengchun; Xu, Qiming; Han, Xun; Wang, Xiandi; Wang, Chunfeng; Zhu, Jing; Pan, Caofeng; Wang, Zhong Lin

    2017-04-06

    Due to the fragility and the poor optoelectronic performances of Si, it is challenging and exciting to fabricate the Si-based flexible light-emitting diode (LED) array devices. Here, a flexible LED array device made of Si microwires-ZnO nanofilm, with the advantages of flexibility, stability, lightweight, and energy savings, is fabricated and can be used as a strain sensor to demonstrate the two-dimensional pressure distribution. Based on piezo-phototronic effect, the intensity of the flexible LED array can be increased more than 3 times (under 60 MPa compressive strains). Additionally, the device is stable and energy saving. The flexible device can still work well after 1000 bending cycles or 6 months placed in the atmosphere, and the power supplied to the flexible LED array is only 8% of the power of the surface-contact LED. The promising Si-based flexible device has wide range application and may revolutionize the technologies of flexible screens, touchpad technology, and smart skin.

  15. Analysis of lignans in Schisandra chinensis and rat plasma by high-performance liquid chromatography diode-array detection, time-of-flight mass spectrometry and quadrupole ion trap mass spectrometry.

    PubMed

    Lou, Ziyang; Zhang, Hai; Gong, Chungui; Zhu, Zhenyu; Zhao, Liang; Xu, Yuanjie; Wang, Bin; Zhang, Guoqing

    2009-03-01

    High-performance liquid chromatography/diode-array detection (HPLC/DAD), time-of-flight mass spectrometry (HPLC/TOFMS) and quadrupole ion trap mass spectrometry (HPLC/QIT-MS) were used for separation, identification and structural analysis of lignans in Schisandra chinensis and rat plasma after oral administration of the herbal extract. Six lignans in Schisandra chinensis extract were identified unambiguously by comparing the retention time, their characteristic ultraviolet (UV) absorption and accurate mass measurement. A formula database of known lignans in Schisandra chinensis was established, against which the other 15 lignans were identified effectively based on the accurate extract masses and formulae acquired by HPLC/TOFMS. In order to distinguish the isomers, multi-stage mass spectrometry (ion trap mass spectrometry, MSn) was also used. The fragmentation behavior of the lignans in the ion trap mass spectrometer was studied by the six lignan standards, and their fragmentation rules in MSn spectra were summarized. These deduced fragmentation rules of lignans were successfully implemented in distinguishing the three groups of isomers in Schisandra chinensis by HPLC/QIT-MS. By using the three different analytical techniques, 21 lignans in Schisandra chinensis were identified within 30 min. After oral administration of the extract, 11 lignans in rat plasma were detected and identified by comparing their retention time, characteristic UV absorption and accurate mass measurement of peaks in HPLC/TOFMS chromatograms of the herbal extract. Finally, HPLC/TOFMS fingerprints of Schisandra chinensis in vitro and rat plasma in vivo were established. It is concluded that a rapid and effective method based on three analytical techniques for identification of chemical components was established, which is useful for rapid identification of multiple components in Schisandra chinensis in vitro and in vivo. In addition, it can provide help for further pharmacology and action

  16. Determination of brilliant green from fish pond water using carbon nanotube assisted pseudo-stir bar solid/liquid microextraction combined with UV-vis spectroscopy-diode array detection

    NASA Astrophysics Data System (ADS)

    Es'haghi, Zarrin; Khooni, Maliheh Ahmadi-Kalateh; Heidari, Tahereh

    2011-08-01

    This paper describes the development of a new design of hollow fiber solid/liquid phase microextraction (HF-SLPME) for determination of brilliant green (BG) residues in water fish ponds. This method consists of an aqueous donor phase and carbon nanotube reinforced organic solvent (acceptor phase) operated in direct immersion sampling mode. The multi-walled carbon nanotube dispersed in the organic solvent is held in the pores and lumen of a porous polypropylene hollow fiber. It is in contact directly with the aqueous donor phase. In this method the solid/liquid extractor phase is supported using a polypropylene hollow fiber membrane. Both ends of the hollow fiber segment are sealed with magnetic stoppers. This device is placed inside the donor solution and plays the rule of a pseudo-stir bar. It is disposable, so single use of the fiber reduces the risk of carry-over problems. Brilliant green (BG) after extraction from the aqueous samples with mentioned HF-SLPME device was determined by ultraviolet-visible spectroscopy with diode array detection (UV-vis/DAD). The absorption wavelength was set to 625 nm ( λmax). The effect of different variables on the extraction was evaluated and optimized to enhance the sensitivity and extraction efficiency of the proposed method. The calibration curve was linear in the range of 1.00-10,000 μg L -1 of BG in the initial solution with R2 = 0.979. Detection limit, based on three times the standard deviation of the blank, was 0.55 μg L -1. All experiments were carried out at room temperature (25 ± 0.5 °C).

  17. High efficiency 2 micrometer laser utilizing wing-pumped Tm{sup 3+} and a laser diode array end-pumping architecture

    DOEpatents

    Beach, R.J.

    1997-11-18

    Wing pumping a Tm{sup 3+} doped, end pumped solid state laser generates 2 {micro}m laser radiation at high average powers with high efficiency. Using laser diode arrays to end-pump the laser rod or slab in the wing of the Tm{sup 3+} absorption band near 785 nm results in 2-for-1 quantum efficiency in Tm{sup 3+} because high Tm{sup 3+} concentrations can be used. Wing pumping allows the thermal power generated in the rod or slab to be distributed over a large enough volume to make thermal management practical in the laser gain medium even at high average power operation. The approach is applicable to CW, Q-switched, and rep-pulsed free-laser operation. 7 figs.

  18. High efficiency 2 micrometer laser utilizing wing-pumped Tm.sup.3+ and a laser diode array end-pumping architecture

    DOEpatents

    Beach, Raymond J.

    1997-01-01

    Wing pumping a Tm.sup.3+ doped, end pumped solid state laser generates 2 .mu.m laser radiation at high average powers with high efficiency. Using laser diode arrays to end-pump the laser rod or slab in the wing of the Tm.sup.3+ absorption band near 785 nm results in 2-for-1 quantum efficiency in Tm.sup.3+ because high Tm.sup.3+ concentrations can be used. Wing pumping allows the thermal power generated in the rod or slab to be distributed over a large enough volume to make thermal management practical in the laser gain medium even at high average power operation. The approach is applicable to CW, Q-switched, and rep-pulsed free-laser operation.

  19. Simultaneous Detection of Sulfamethoxazole, Diclofenac, Carbamazepine, and Bezafibrate by Solid Phase Extraction and High Performance Liquid Chromatography with Diode Array Detection

    NASA Astrophysics Data System (ADS)

    Zhou, Z.; Jiang, J.-Q.

    2014-05-01

    A method of solid phase extraction (SPE) coupled with high performance liquid chromatography and diode array detection (HPLC-DAD) was studied for the simultaneous determination of sulfamethoxazole (SMX), diclofenac (DCF), carbamazepine (CBZ), and bezafi brate (BZF) in test solutions. The target compounds were extracted by SPE from samples, and the resulting elutes were analyzed using a HPLC-DAD system at wavelengths of 270, 280, 290, and 230 nm for SMX, DCF, CBZ, and BZF, respectively. This method shows good recoveries for SMX, DCF, CBZ, and BZF with mean recoveries of 89.7 ± 9.3%, 86.1 ± 7.6%, 95.0 ± 6.5%, and 94.0 ± 5.4%, respectively.

  20. Quality control of flavonoids in Ginkgo biloba leaves by high-performance liquid chromatography with diode array detection and on-line radical scavenging activity detection.

    PubMed

    Ding, Xiao-Ping; Qi, Jin; Chang, Yan-Xu; Mu, Ling-Li; Zhu, Dan-Ni; Yu, Bo-Yang

    2009-03-13

    Flavonoids in plants used for the treatment of various cardiovascular, cancer diseases have been reported to possess potential protective effects against oxidative injury. Ginkgo biloba leaves, known for their antioxidant activity, were chosen for this study. In this paper, 12 flavonoids in G. biloba leaves were identified by HPLC-diode array detection (DAD)-electrospray ionization MS. HPLC-DAD coupled with chemiluminescence detection was used to determine free radical scavenging activity of flavonoids. It was found that the flavonol glycosides could markedly inhibit the luminescent signal, which indicated that they are mainly responsible for the antioxidant activities of G. biloba leaves. Total antioxidant activity of these flavonoids was used to evaluate the differences of G. biloba leaves collected in 13 habitats. The combination of chemical and activity analysis can provide a valid method to quantify the bioactive components in G. biloba leaves, and this may be a more rational approach to the quality assessment of G. biloba leaves.

  1. A deuterium-labelling mass spectrometry-tandem diode-array detector screening method for rapid discovery of naturally occurring electrophiles.

    PubMed

    Zhang, Xiaoyu; Luo, Liping; Ma, Zhongjun

    2011-07-01

    Because electrophiles regulate many signalling pathways in cells, by modifying cysteine residues in proteins, they have a wide range of biological activity. In this study, a deuterium-labelling mass spectrometry-tandem diode-array detector (MS-DAD) screening method was established for rapid discovery of naturally occurring electrophiles. Glutathione (GSH) was used as a probe and incubated with natural product extracts. To distinguish different types of electrophile, incubation was performed in two reaction solvents, H(2)O and D(2)O. Ten types of naturally occurring electrophile were chosen, on the basis of their properties, to undergo the screening assay. By using this screening method, we successfully discovered the bioactive electrophile 4-hydroxyderricin in an ethanol extract of Angelica keiskei. This electrophile had potent NAD(P)H:quinone oxidoreductase 1 (NQO1)-inducing activity at a concentration of 20 μmol L(-1).

  2. Quantitative profiling of retinyl esters in milk from different ruminant species by using high performance liquid chromatography-diode array detection-tandem mass spectrometry.

    PubMed

    Rocchi, Silvia; Caretti, Fulvia; Gentili, Alessandra; Curini, Roberta; Perret, Daniela; Pérez-Fernández, Virginia

    2016-11-15

    An effective high performance liquid chromatography-diode array detection-tandem mass spectrometry (HPLC-DAD-MS/MS) analytical approach was developed for retinoid profiling in raw milk samples (cow, buffalo, ewe, and goat). The analytes were isolated by means of liquid-liquid extraction, including a "lipid freezing" step, with yields exceeding 66%. Since the positive atmospheric pressure chemical ionisation mass spectrometry (APCI-MS) detection is not completely selective, a reliable identification has been accomplished by fully separating the analytes on a tandem C18/C30 column system under non-aqueous reversed phase (NARP) chromatography conditions. After validation, different milk varieties obtained from pasture-fed animals were analysed, providing, for the first time, the retinoid composition of both buffalo's and ewe's milk. According to the literature, retinyl palmitate has been found to be the most abundant vitamin A vitamer, but retinyl oleate is the prevalent form in the caprine milk.

  3. Using second-order calibration method based on trilinear decomposition algorithms coupled with high performance liquid chromatography with diode array detector for determination of quinolones in honey samples.

    PubMed

    Yu, Yong-Jie; Wu, Hai-Long; Shao, Sheng-Zhi; Kang, Chao; Zhao, Juan; Wang, Yu; Zhu, Shao-Hua; Yu, Ru-Qin

    2011-09-15

    A novel strategy that combines the second-order calibration method based on the trilinear decomposition algorithms with high performance liquid chromatography with diode array detector (HPLC-DAD) was developed to mathematically separate the overlapped peaks and to quantify quinolones in honey samples. The HPLC-DAD data were obtained within a short time in isocratic mode. The developed method could be applied to determine 12 quinolones at the same time even in the presence of uncalibrated interfering components in complex background. To access the performance of the proposed strategy for the determination of quinolones in honey samples, the figures of merit were employed. The limits of quantitation for all analytes were within the range 1.2-56.7 μg kg(-1). The work presented in this paper illustrated the suitability and interesting potential of combining second-order calibration method with second-order analytical instrument for multi-residue analysis in honey samples.

  4. Determination of the anthraquinones aloe-emodin and aloin-A by liquid chromatography with mass spectrometric and diode array detection.

    PubMed

    Elsohly, Mahmoud A; Gul, Waseem; Avula, Bharathi; Khan, Ikhlas A

    2007-01-01

    Methods using liquid chromatography/mass spectrometry (LC/MS) and LC with diode array detection (DAD) in the UV range (LC/UV) were developed for the determination of low levels of the anthraquinones aloe-emodin and aloin-A (barbaloin) in aloe-based products. The methods were used to analyze several commercial products (liquids, semisolids, and solids) for the 2 anthraquinones. The wavelengths used for quantification of aloin-A, aloe-emodin, and emodin (internal standard) by DAD were 357, 257, and 289 nm, respectively. The on-column sensitivities were 0.25 and 0.05 ng by LC/UV and 0.01 and 0.025 ng by LC/MS for aloin-A and aloe-emodin, respectively. The methods are simple and sensitive and provide reproducible results; therefore, they are suitable for the determination of these anthraquinones in various aloe-based products.

  5. Direct characterization of aqueous extract of Hibiscus sabdariffa using HPLC with diode array detection coupled to ESI and ion trap MS.

    PubMed

    Rodríguez-Medina, Inmaculada C; Beltrán-Debón, Raúl; Molina, Vicente Micol; Alonso-Villaverde, Carlos; Joven, Jorge; Menéndez, Javier A; Segura-Carretero, Antonio; Fernández-Gutiérrez, Alberto

    2009-10-01

    The phenolic fraction and other polar compounds of the Hibiscus sabdariffa were separated and identified by HPLC with diode array detection coupled to electrospray TOF and IT tandem MS (DAD-HPLC-ESI-TOF-MS and IT-MS). The H. sabdariffa aqueous extract was filtered and directly injected into the LC system. The analysis of the compounds was carried out by RP HPLC coupled to DAD and TOF-MS in order to obtain molecular formula and exact mass. Posterior analyses with IT-MS were performed and the fragmentation pattern and confirmation of the structures were achieved. The H. sabdariffa samples were successfully analyzed in positive and negative ionization modes with two optimized linear gradients. In positive mode, the two most representative anthocyanins and other compounds were identified whereas the phenolic fraction, hydroxycitric acid and its lactone were identified using the negative ionization mode.

  6. Analysis by high-performance liquid chromatography diode array detection mass spectrometry of phenolic compounds in fruit of Eucalyptus globulus cultivated in Algeria.

    PubMed

    Boulekbache-Makhlouf, Lila; Meudec, Emmanuelle; Chibane, Mohamed; Mazauric, Jean-Paul; Slimani, Sakina; Henry, Max; Cheynier, Veronique; Madani, Khodir

    2010-12-22

    A method based on high-performance liquid chromatography coupled with diode array detection and electrospray ionization mass spectrometry (HPLC-DAD-ESI-MS) following fractionation by chromatography on a Sephadex LH-20 column has been developed to determine the phenolic composition of fruit of Eucalyptus globulus growing in Algeria. The presence of 18 gallotannins, 26 ellagitannins, and 2 flavonols was established. Tentative identification is provided for these compounds on the basis of UV-visible spectra and mass spectrometry data. Most compounds described in this study have not previously detected in fruit of E. globulus. Moreover, this is the first report of methyl digalloyl diglucose, 3,3'-O-dimethylellagic acid 4-O-β-glucopyranoside, ellagic acid hexose, methyl ellagic acid pentose, methyltetragalloylglucose, and valoneic acid isomers (sanguisorbic, flavogallic acid dilactone) in the genus Eucalyptus. Quantitatively, ellagic acid and its derivatives, including ellagitannins, are largely predominant.

  7. Simultaneous extraction and analysis by high performance liquid chromatography coupled to diode array and mass spectrometric detectors of bixin and phenolic compounds from annatto seeds.

    PubMed

    Chisté, Renan Campos; Yamashita, Fábio; Gozzo, Fábio Cesar; Mercadante, Adriana Zerlotti

    2011-01-07

    This study was designed to identify and quantify the carotenoids and phenolic compounds from annatto seeds using high performance liquid chromatography coupled to diode array and mass spectrometer detectors (HPLC-DAD-MS/MS). Furthermore, using response surface methodology, an optimized procedure for simultaneous extraction of these compounds was established. In addition to bixin, known to be the main carotenoid in annatto seeds, hypolaetin and a caffeoyl acid derivative were identified as the main phenolic compounds. The optimized procedure involved 15 extractions using acetone:methanol:water (50:40:10, v/v/v) as solvent, a solid-liquid ratio of 1:9 (m/v) and an extraction time of 5 min. Validation data indicated that the HPLC method proposed provided good linearity, sensitivity, procedure accuracy, system precision and suggested its suitability for the simultaneous analysis of phenolic compounds and carotenoids in annatto seeds.

  8. Spectral correlation of high-performance liquid chromatography-diode array detection data from two independent chromatographic runs peak tracking in pharmaceutical impurity profiling.

    PubMed

    Li, Wei; Hu, Chang-qin

    2008-05-09

    A novel qualitative analytical method for peak tracking in impurity profiling control by the correlation of spectra was established. Two-dimensional (2D) standard spectrochromatographic data produced by high-performance liquid chromatography with diode array detection (HPLC-DAD) were compared with sample data to develop two-dimensional chromatographic spectral correlative maps. Taking full advantage of separation efficiency of HPLC and spectral specificity of the analytes, the method was successfully used to recognize impurities in quinolone antibacterials, when in combination with relative retention times (RRTs). For the comparison of spectra was expanded to three-dimensional space, simultaneous identification of the chromatographic peaks can be obtained rapidly without preparation and injection of a reference solution, even when the mobile phase changed or the peaks of multi-component samples overlapped.

  9. Compact, passively Q-switched, all-solid-state master oscillator-power amplifier-optical parametric oscillator (MOPA-OPO) system pumped by a fiber-coupled diode laser generating high-brightness, tunable, ultraviolet radiation.

    PubMed

    Peuser, Peter; Platz, Willi; Fix, Andreas; Ehret, Gerhard; Meister, Alexander; Haag, Matthias; Zolichowski, Paul

    2009-07-01

    We report on a compact, tunable ultraviolet laser system that consists of an optical parametric oscillator (OPO) and a longitudinally diode-pumped Nd:YAG master oscillator-power amplifier (MOPA). The pump energy for the whole laser system is supplied via a single delivery fiber. Nanosecond pulses are produced by an oscillator that is passively Q-switched by a Cr(4+):YAG crystal. The OPO is pumped by the second harmonic of the Nd:YAG MOPA. Continuously tunable radiation is generated by an intracavity sum-frequency mixing process within the OPO in the range of 245-260 nm with high beam quality. Maximum pulse energies of 1.2 mJ were achieved, which correspond to an optical efficiency of 3.75%, relating to the pulse energy of the MOPA at 1064 nm.

  10. KOH based selective wet chemical etching of AlN, Al{sub x}Ga{sub 1−x}N, and GaN crystals: A way towards substrate removal in deep ultraviolet-light emitting diode

    SciTech Connect

    Guo, W. Kirste, R.; Bryan, I.; Bryan, Z.; Hussey, L.; Reddy, P.; Collazo, R.; Sitar, Z.; Tweedie, J.

    2015-02-23

    A controllable and smooth potassium hydroxide-based wet etching technique was developed for the AlGaN system. High selectivity between AlN and Al{sub x}Ga{sub 1−x}N (up to 12×) was found to be critical in achieving effective substrate thinning or removal for AlGaN-based deep ultraviolet light emitting diodes, thus increasing light extraction efficiency. The mechanism of high selectivity of AlGaN as a function of Al composition can be explained as related to the formation and dissolution of oxide/hydroxide on top of N-polar surface. Cross-sectional transmission electron microscopic analysis served as ultimate proof that these hillocks were not related to underlying threading dislocations.

  11. Light extraction enhancement of 265 nm deep-ultraviolet light-emitting diodes with over 90 mW output power via an AlN hybrid nanostructure

    SciTech Connect

    Inoue, Shin-ichiro; Naoki, Tamari; Kinoshita, Toru; Obata, Toshiyuki; Yanagi, Hiroyuki

    2015-03-30

    Deep-ultraviolet (DUV) aluminum gallium nitride-based light-emitting diodes (LEDs) on transparent aluminum nitride (AlN) substrates with high light extraction efficiency and high power are proposed and demonstrated. The AlN bottom side surface configuration, which is composed of a hybrid structure of photonic crystals and subwavelength nanostructures, has been designed using finite-difference time-domain calculations to enhance light extraction. We have experimentally demonstrated an output power improvement of up to 196% as a result of the use of the embedded high-light-extraction hybrid nanophotonic structure. The DUV-LEDs produced have demonstrated output power as high as 90 mW in DC operation at a peak emission wavelength of 265 nm.

  12. KOH based selective wet chemical etching of AlN, AlxGa1-xN, and GaN crystals: A way towards substrate removal in deep ultraviolet-light emitting diode

    SciTech Connect

    Guo, W; Kirste, R; Bryan, I; Bryan, Z; Hussey, L; Reddy, P; Tweedie, J; Collazo, R; Sitar, Z

    2015-02-23

    A controllable and smooth potassium hydroxide-based wet etching technique was developed for the AlGaN system. High selectivity between AlN and AlxGa1-xN (up to 12 x) was found to be critical in achieving effective substrate thinning or removal for AlGaN-based deep ultraviolet light emitting diodes, thus increasing light extraction efficiency. The mechanism of high selectivity of AlGaN as a function of Al composition can be explained as related to the formation and dissolution of oxide/hydroxide on top of N-polar surface. Cross-sectional transmission electron microscopic analysis served as ultimate proof that these hillocks were not related to underlying threading dislocations. (C) 2015 AIP Publishing LLC.

  13. Qualitative and quantitative determination of polyacetylenes in different Bupleurum species by high performance liquid chromatography with diode array detector and mass spectrometry.

    PubMed

    Huang, Hai-Qiang; Su, Juan; Zhang, Xi; Shan, Lei; Zhang, Wei-Dong

    2011-02-25

    Polyacetylenes are main toxic ingredients in Bupleurum longiradiatum, a poisonous plant that has ever been misused as substitutes for Chaihu (Bupleuri Radix). For the first time, a high-performance liquid chromatography method coupled with diode array detector and mass spectrometry (HPLC-DAD-MS) was developed for qualitative and quantitative analysis of nine polyacetylenes in Bupleurum species. All references, including two new polyacetylenes, were isolated from B. longiradiatum and purified using a semi-preparation HPLC chromatography. The analysis was performed on a TSKgel ODS-100V C18 column (3 μm, 150 mm x 4.6 mm i.d.) using a gradient system of acetonitrile and water, with diode array detection (254 nm). The method was validated for linearity, precision, accuracy, limit of detection and quantification. A total of 27 Bupleurum samples were examined with this method, which showed a great variety in the distribution and contents of the polyacetylenes. It was found that polyacetylenes (1-8) were the main ingredients in B. longiradiatum, while a few kinds of polyacetylenes (5-8) were also identified in B. smithii, B. smithii var. parvifolium, B. bicaule and B. angustissimum. However, no polyacetylenes (1-9) were detected in the authentic Chaihu samples and the other Bupleurum species. The results indicated that the toxic B. longiradiatum could readily be distinguished from other medicinal Bupleurum species based on the polyacetylene profiles, and the guidelines and quality control of polyacetylenes for Chaihu are useful. The acute toxicity of the ethanol extract of B. longiradiatum and its fractions was also investigated.

  14. Sr₂ZnWO₆:Eu³⁺, Bi³⁺, Li⁺: a potential white-emitting phosphor for near-ultraviolet white light-emitting diodes.

    PubMed

    Ma, Yuanyuan; Ran, Weiguang; Li, Weina; Ren, Chunyan; Jiang, Haiyan; Shi, Jinsheng

    2016-05-01

    A series of Sr2ZnWO6 phosphors co-doped with Eu(3+), Bi(3+) and Li(+) were prepared using the Pechini method. The samples were tested using X-ray diffraction and luminescence spectroscopy. The results show that the samples can be effectively excited by near-ultraviolet (UV) and UV light. The introduction of Bi(3+) and Li(+) significantly enhances the fluorescence emission of Sr2ZnWO6 :Eu(3+) and changes the light emitted by the phosphors from bluish-green to white. When excited at 371 nm, Sr(2-x-z)Zn(1-y)WO6:xEu(3+), yBi(3+), zLi(+) (x = 0.05, y = 0.05, z = 0.05, 0.1 and 0.15) samples emit high-performance white light. Intense red-orange emission is also observed when excited by UV light. The obtained phosphor is a potential white-emitting phosphor that could meet the needs of excitation sources with near-UV chips. In addition, this phosphor might have promising application as a red-orange emitting phosphor for white light-emitting diodes based on UV light-emitting diodes.

  15. High-speed GaN/GaInN nanowire array light-emitting diode on silicon(111).

    PubMed

    Koester, Robert; Sager, Daniel; Quitsch, Wolf-Alexander; Pfingsten, Oliver; Poloczek, Artur; Blumenthal, Sarah; Keller, Gregor; Prost, Werner; Bacher, Gerd; Tegude, Franz-Josef

    2015-04-08

    The high speed on-off performance of GaN-based light-emitting diodes (LEDs) grown in c-plane direction is limited by long carrier lifetimes caused by spontaneous and piezoelectric polarization. This work demonstrates that this limitation can be overcome by m-planar core-shell InGaN/GaN nanowire LEDs grown on Si(111). Time-resolved electroluminescence studies exhibit 90-10% rise- and fall-times of about 220 ps under GHz electrical excitation. The data underline the potential of these devices for optical data communication in polymer fibers and free space.

  16. ZnO-nanorod-array/p-GaN high-performance ultra-violet light emitting devices prepared by simple solution synthesis

    NASA Astrophysics Data System (ADS)

    Jha, Shrawan Kumar; Luan, Chunyan; To, Chap Hang; Kutsay, Oleksandr; Kováč, Jaroslav; Zapien, Juan Antonio; Bello, Igor; Lee, Shuit-Tong

    2012-11-01

    Pure ultra-violet (UV) (378 nm) electroluminescence (EL) from zinc oxide (ZnO)-nanorod-array/p-gallium nitride (GaN) light emitting devices (LEDs) is demonstrated at low bias-voltages (˜4.3 V). Devices were prepared merely by solution-synthesis, without any involvement of sophisticated material growth techniques or preparation methods. Three different luminescence characterization techniques, i.e., photo-luminescence, cathodo-luminescence, and EL, provided insight into the nature of the UV emission mechanism in solution-synthesized LEDs. Bias dependent EL behaviour revealed blue-shift of EL peaks and increased peak sharpness, with increasing the operating voltage. Accelerated bias stress tests showed very stable and repeatable electrical and EL performance of the solution-synthesized nanorod LEDs.

  17. ZnO homojunction photodiodes based on Sb-doped p-type nanowire array and n-type film for ultraviolet detection

    SciTech Connect

    Wang Guoping; Chu Sheng; Zhan Ning; Liu Jianlin; Lin Yuqing; Chernyak, Leonid

    2011-01-24

    ZnO p-n homojunctions based on Sb-doped p-type nanowire array and n-type film were grown by combining chemical vapor deposition (for nanowires) with molecular-beam epitaxy (for film). Indium tin oxide and Ti/Au were used as contacts to the ZnO nanowires and film, respectively. Characteristics of field-effect transistors using ZnO nanowires as channels indicate p-type conductivity of the nanowires. Electron beam induced current profiling confirmed the existence of ZnO p-n homojunction. Rectifying I-V characteristic showed a turn-on voltage of around 3 V. Very good response to ultraviolet light illumination was observed from photocurrent measurements.

  18. Chemically synthesized nanowire TiO2/ZnO core-shell p-n junction array for high sensitivity ultraviolet photodetector

    NASA Astrophysics Data System (ADS)

    Dao, T. D.; Dang, C. T. T.; Han, G.; Hoang, C. V.; Yi, W.; Narayanamurti, V.; Nagao, T.

    2013-11-01

    A sol-gel-based ultrathin TiO2 lamination coating was adapted to a hydrothermally grown ZnO nanowire array to realize an all-oxide ultra-sensitive p-n photodiode. The core-shell heterojunction—the key component of the device—is composed of a 5-10 nm thick p-type Cr-doped TiO2 nanoshell and n-type single-crystalline ZnO nanowires (50 nm radius). Owing to the enhanced light scattering and carrier separation in the core-shell architecture, this device exhibits the highest performance among the ZnO nanowire-based photodetectors. At a moderate reverse bias of -5 V and under ultraviolet light illumination at 104 μW, it shows a switch current ratio of 140 and a responsivity as large as 250 A/W, while it shows nearly no response to the infrared and visible light.

  19. One-step solvothermal deposition of ZnO nanorod arrays on a wood surface for robust superamphiphobic performance and superior ultraviolet resistance.

    PubMed

    Yao, Qiufang; Wang, Chao; Fan, Bitao; Wang, Hanwei; Sun, Qingfeng; Jin, Chunde; Zhang, Hong

    2016-10-24

    In the present paper, uniformly large-scale wurtzite-structured ZnO nanorod arrays (ZNAs) were deposited onto a wood surface through a one-step solvothermal method. The as-prepared samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG), and differential thermal analysis (DTA). ZNAs with a diameter of approximately 85 nm and a length of approximately 1.5 μm were chemically bonded onto the wood surface through hydrogen bonds. The superamphiphobic performance and ultraviolet resistance were measured and evaluated by water or oil contact angles (WCA or OCA) and roll-off angles, sand abrasion tests and an artificially accelerated ageing test. The results show that the ZNA-treated wood demonstrates a robust superamphiphobic performance under mechanical impact, corrosive liquids, intermittent and transpositional temperatures, and water spray. Additionally, the as-prepared wood sample shows superior ultraviolet resistance.

  20. One-step solvothermal deposition of ZnO nanorod arrays on a wood surface for robust superamphiphobic performance and superior ultraviolet resistance

    PubMed Central

    Yao, Qiufang; Wang, Chao; Fan, Bitao; Wang, Hanwei; Sun, Qingfeng; Jin, Chunde; Zhang, Hong

    2016-01-01

    In the present paper, uniformly large-scale wurtzite-structured ZnO nanorod arrays (ZNAs) were deposited onto a wood surface through a one-step solvothermal method. The as-prepared samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG), and differential thermal analysis (DTA). ZNAs with a diameter of approximately 85 nm and a length of approximately 1.5 μm were chemically bonded onto the wood surface through hydrogen bonds. The superamphiphobic performance and ultraviolet resistance were measured and evaluated by water or oil contact angles (WCA or OCA) and roll-off angles, sand abrasion tests and an artificially accelerated ageing test. The results show that the ZNA-treated wood demonstrates a robust superamphiphobic performance under mechanical impact, corrosive liquids, intermittent and transpositional temperatures, and water spray. Additionally, the as-prepared wood sample shows superior ultraviolet resistance. PMID:27775091

  1. One-step solvothermal deposition of ZnO nanorod arrays on a wood surface for robust superamphiphobic performance and superior ultraviolet resistance

    NASA Astrophysics Data System (ADS)

    Yao, Qiufang; Wang, Chao; Fan, Bitao; Wang, Hanwei; Sun, Qingfeng; Jin, Chunde; Zhang, Hong

    2016-10-01

    In the present paper, uniformly large-scale wurtzite-structured ZnO nanorod arrays (ZNAs) were deposited onto a wood surface through a one-step solvothermal method. The as-prepared samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG), and differential thermal analysis (DTA). ZNAs with a diameter of approximately 85 nm and a length of approximately 1.5 μm were chemically bonded onto the wood surface through hydrogen bonds. The superamphiphobic performance and ultraviolet resistance were measured and evaluated by water or oil contact angles (WCA or OCA) and roll-off angles, sand abrasion tests and an artificially accelerated ageing test. The results show that the ZNA-treated wood demonstrates a robust superamphiphobic performance under mechanical impact, corrosive liquids, intermittent and transpositional temperatures, and water spray. Additionally, the as-prepared wood sample shows superior ultraviolet resistance.

  2. A series of color tunable yellow-orange-red-emitting SrWO4:RE (Sm3+, Eu3+-Sm3+) phosphor for near ultraviolet and blue light-based warm white light emitting diodes

    NASA Astrophysics Data System (ADS)

    Ren, Yandong; Liu, Yonghao; Yang, Rui

    2016-03-01

    A series of wide-range-tunable light emissive SrWO4:Sm3+, SrWO4:Sm3+,Eu3+ phosphors were synthesized via the simple co-precipitation method. The charge compensation can greatly improve SrWO4: Sm3+ phosphors luminous intensity. The critical distance, ηT and energy transfer mechanism of SrWO4:0.01Sm3+,0.12Eu3+ were studied. These obtained phosphors exhibit a high luminous efficiency, purity and lower color temperature of the comfortable warm white LEDs. Hues varying have been generated by appropriately tuning the Sm3+ ions concentration, excitation wavelength or Sm3+, Eu3+ co-doping, which have the color tunable wide gamut light covering the yellow-green, greenish-yellow, yellow, yellow orange, orange, reddish orange and red chromaticity region. In particular, SrWO4:0.01Sm3+,0.12Eu3+ phosphors excited at 404 and 480 nm have higher color saturation than commercially available Y2O2S:Eu3+ red phosphor. These phosphors can be excited efficiently using commercial ultraviolet, blue laser diodes and LEDs, and can be used for developing new color light sources, fluorescent display devices, ultraviolet-sensors and tunable visible lasers.

  3. Photovoltaic module bypass diode encapsulation

    NASA Technical Reports Server (NTRS)

    Shepard, N. J., Jr.

    1983-01-01

    The design and processing techniques necessary to incorporate bypass diodes within the module encapsulant are presented. The Semicon PN junction diode cells were selected. Diode junction to heat spreader thermal resistance measurements, performed on a variety of mounted diode chip types and sizes, have yielded values which are consistently below 1 deg C per watt, but show some instability when thermally cycled over the temperature range from -40 to 150 deg C. Three representative experimental modules, each incorporating integral bypass diode/heat spreader assemblies of various sizes, were designed. Thermal testing of these modules enabled the formulation of a recommended heat spreader plate sizing relationship. The production cost of three encapsulated bypass diode/heat spreader assemblies were compared with similarly rated externally mounted packaged diodes. It is concluded that, when proper designed and installed, these bypass diode devices will improve the overall reliability of a terrestrial array over a 20 year design lifetime.

  4. Second-order capillary electrophoresis diode array detector data modeled with the Tucker3 algorithm: A novel strategy for Argentinean white wine discrimination respect to grape variety.

    PubMed

    Azcarate, Silvana M; de Araújo Gomes, Adriano; Vera-Candioti, Luciana; Cesar Ugulino de Araújo, Mário; Camiña, José M; Goicoechea, Héctor C

    2016-07-01

    Data obtained by capillary electrophoresis with diode array detection (CE-DAD) were modeled with the purpose to discriminate Argentinean white wines samples produced from three grape varieties (Torrontés, Chardonnay, and Sauvignon blanc). Thirty-eight samples of commercial white wine from four wine-producing provinces of Argentina (Mendoza, San Juan, Salta, and Rio Negro) were analyzed. CE-DAD matrices with dimensions of 421 elution times (from 1.17 to 7.39 minutes) × 71 wavelengths (from 227 to 367 nm) were joined in a three way data array and decomposed by Tucker3 method under non-negativity constraint, employing 18, 18 and six factors in the modes 1, 2 and 3, respectively. Using the scores of Tucker model, it was possible to discriminate samples of Argentinean white wine by linear discriminant analysis and Kernel linear discriminant analysis. Core element analysis of the Tucker3 model allows identifying the loading profiles in spectral mode related to Argentinean white wine samples.

  5. Nanospherical-lens lithographical Ag nanodisk arrays embedded in p-GaN for localized surface plasmon-enhanced blue light emitting diodes

    SciTech Connect

    Wei, Tongbo Wu, Kui; Sun, Bo; Zhang, Yonghui; Chen, Yu; Huo, Ziqiang; Hu, Qiang; Wang, Junxi; Zeng, Yiping; Li, Jinmin; Lan, Ding

    2014-06-15

    Large-scale Ag nanodisks (NDs) arrays fabricated using nanospherical-lens lithography (NLL) are embedded in p-GaN layer of an InGaN/GaN light-emitting diode (LED) for generating localized surface plasmon (LSP) coupling with the radiating dipoles in the quantum-well (QWs). Based on the Ag NDs with the controlled surface coverage, LSP leads to the improved crystalline quality of regrowth p-GaN, increased photoluminescence (PL) intensity, reduced PL decay time, and enhanced output power of LED. Compared with the LED without Ag NDs, the optical output power at a current of 350 mA of the LSP-enhanced LEDs with Ag NDs having a distance of 20 and 35 nm to QWs is increased by 26.7% and 31.1%, respectively. The electrical characteristics and optical properties of LEDs with embedded Ag NPs are dependent on the distance of between Ag NPs and QWs region. The LED with Ag NDs array structure is also found to exhibit reduced emission divergence, compared to that without Ag NDs.

  6. Self-Injection Locking Of Diode Lasers

    NASA Technical Reports Server (NTRS)

    Hemmati, H.

    1991-01-01

    Simple optical coupling scheme locks array of gain-guided diode lasers into oscillation in single mode and with single-lobed output beam. Selective feedback from thin etalon self-injection-locks array into desired mode. One application of new scheme for pumping of neodymium: yttrium aluminum garnet lasers with diode-laser arrays.

  7. High Performance Liquid Chromatography-Diode Array Detector Method for the Simultaneous Determination of Five Compounds in the Pulp and Seed of Sea Buckthorn

    PubMed Central

    Zhao, Lu; Wen, E; Upur, Halmuart; Tian, Shuge

    2017-01-01

    Context: Sea buckthorn (Hippophae rhamnoides L.) as a traditional Chinese medicinal plant has various uses in Xinjiang. Objective: A reversed-phase rapid-resolution liquid-chromatography method with diode array detector was developed for simultaneous determination of protocatechuic acid, rutin, quercetin, kaempferol, and isorhamnetin in the pulp and seed of sea buckthorn, a widely used traditional Chinese medicine for promoting metabolism and treating scurvy and other diseases. Settings and design: Compounds were separated on an Agilent ZORBAX SB-C18 column (4.6 mm × 250 mm, 5 μm; USA) with gradient elution using methanol and 0.4% phosphoric acid (v/v) at 1.0 mL/min. Detection wavelength was set at 280 nm. Materials and Methods: The fruits of wild sea buckthorn were collected from Wushi County in Aksu, Xinjiang Province. Statistical performances: The RSD of precision test of the five compounds were in the range of 0.60-2.22%, and the average recoveries ranged from 97.36% to 101.19%. Good linearity between specific chromatographic peak and component qualities were observed in the investigated ranges for all the analytes (R2 > 0.9997). Results: The proposed method was successfully applied to determine the levels of five active components in sea buckthorn samples from Aksu in Xinjiang. Conclusions: The proposed method is simple, fast, sensitive, accurate, and suitable for quantitative assessment of the pulp and seed of sea buckthorn. SUMMARY Quantitative analysis method of protocatechuic acid, rutin, quercetin, kaempferol, and isorhamnetin in the extract of sea buckthorn pulp and seed is developed by high-performance liquid chromatography (HPLC) diode array detection.This method is simple and accurate; has strong specificity, good precision, and high recovery rate; and provides a reliable basis for further development of the substances in the pulp and seed of sea buckthorn.The method is widely used for content determination of active ingredients or physiologically

  8. Sensitivity of a helical diode array device to delivery errors in IMRT treatment and establishment of tolerance level for pretreatment QA.

    PubMed

    García-Vicente, Feliciano; Fernández, Virginia; Bermúdez, Rocío; Gómez, Alberto; Pérez, Leopoldo; Zapatero, Almudena; Torres, Juan J

    2012-01-05

    The aim of this study is to determine the gantry angle and multileaf collimator (MLC) gap error-detection threshold of a diode helical array with an inserted micro-ionization chamber in order to use this device for the pretreatment quality assurance (QA) of intensity-modulated radiation therapy (IMRT) treatments. Implications on the dose-volume histograms (DVHs) of the patient treatments will also be considered for the establishment of a QA protocol with a reasonable tolerance level. Three dynamic IMRT HN (head and neck) and prostate treatments were studied. Random and systematic variations of gantry angle and systematic errors in MLC gap width of the clinical treatments were analyzed in order to establish the detection sensitivity of the array. The associated clinical significance was studied introducing the same errors in the treatment plan based on the patients' computed tomography (CT) and calculating the corresponding DVHs. The Gamma (3%/3 mm) presented a 4% variation in failure rate for a rotation error of 1° for both types of treatment. Both systematic and random errors in gantry rotation angle have little effect on the patients' DVHs. MLC gap width errors of 1 mm and 2 mm in the prostate treatments imply a mean variation in isocenter-measured absorbed dose of 2.1% and 4.1%, respectively. In the case of HN, these errors entail a change in measured isocenter dose of 4.7% and 8.6%, respectively. The variation observed in the DVHs of the patients was, basically, a global displacement of the curves proportional to the isocenter dose variation caused by the gap width error. According to the array sensitivity to the analyzed errors and its implication in patient DVHs, a tolerance of 95% point passing rate for the gamma criterion 3%/2 mm and an agreement of 2% in isocenter absolute dose have been established as tolerance criteria for our pretreatment IMRT QA protocol.

  9. Analysis of condition for uniform lighting generated by array of light emitting diodes with large view angle.

    PubMed

    Qin, Zong; Wang, Kai; Chen, Fei; Luo, Xiaobing; Liu, Sheng

    2010-08-02

    In this research, the condition for uniform lighting generated by array of LEDs with large view angle was studied. The luminous intensity distribution of LED is not monotone decreasing with view angle. A LED with freeform lens was designed as an example for analysis. In a system based on LEDs designed in house with a thickness of 20mm and rectangular arrangement, the condition for uniform lighting was derived and the analytical results demonstrated that the uniformity was not decreasing monotonously with the increasing of LED-to-LED spacing. The illuminance uniformities were calculated with Monte Carlo ray tracing simulations and the uniformity was found to increase with the increasing of certain LED-to-LED spacings anomalously. Another type of large view angle LED and different arrangements were discussed in addition. Both analysis and simulation results showed that the method is available for LED array lighting system design on the basis of large view angle LED..

  10. Measurement and Simulation of the Variation in Proton-Induced Energy Deposition in Large Silicon Diode Arrays

    NASA Technical Reports Server (NTRS)

    Howe, Christina L.; Weller, Robert A.; Reed, Robert A.; Sierawski, Brian D.; Marshall, Paul W.; Marshall, Cheryl J.; Mendenhall, Marcus H.; Schrimpf, Ronald D.

    2007-01-01

    The proton induced charge deposition in a well characterized silicon P-i-N focal plane array is analyzed with Monte Carlo based simulations. These simulations include all physical processes, together with pile up, to accurately describe the experimental data. Simulation results reveal important high energy events not easily detected through experiment due to low statistics. The effects of each physical mechanism on the device response is shown for a single proton energy as well as a full proton space flux.

  11. White light emission from heterojunction diodes based on surface-oxidized porous Si nanowire arrays and amorphous In-Ga-Zn-O capping

    NASA Astrophysics Data System (ADS)

    Moon, Kyeong-Ju; Lee, Tae Il; Lee, Woong; Myoung, Jae-Min

    2014-03-01

    A novel heterojunction white light emitting diode (LED) structure based on an array of vertically aligned surface-passivated p-type porous Si nanowires (PSiNWs) with n-type amorphous In-Ga-Zn-O (a-IGZO) capping is introduced. PSiNWs were initially synthesized by electroless etching of p-type Si (100) wafers assisted by Ag nanoparticle catalysts and then surface-passivated by thermal oxidation. The nanowires synthesized by metal-assisted electroless etching were found to have longitudinally varying nanoporous morphologies due to differences in the duration of exposure to etching environment. These PSiNWs were optically active with orange red photoluminescence consisting of dark red to yellow emissions attributable to quantum confinement effects and to modified band structures. The LED structures emitted visible white light while exhibiting rectifying current-voltage characteristics. The white light emission was found to be the result of the combination of dark red to yellow emissions originating from the quantum confinement effect within the PSiNWs and green to blue emissions due to the oxygen-deficiency-related recombination centers introduced during the surface oxidation.A novel heterojunction white light emitting diode (LED) structure based on an array of vertically aligned surface-passivated p-type porous Si nanowires (PSiNWs) with n-type amorphous In-Ga-Zn-O (a-IGZO) capping is introduced. PSiNWs were initially synthesized by electroless etching of p-type Si (100) wafers assisted by Ag nanoparticle catalysts and then surface-passivated by thermal oxidation. The nanowires synthesized by metal-assisted electroless etching were found to have longitudinally varying nanoporous morphologies due to differences in the duration of exposure to etching environment. These PSiNWs were optically active with orange red photoluminescence consisting of dark red to yellow emissions attributable to quantum confinement effects and to modified band structures. The LED structures

  12. Evaluation of the sensitivity of two 3D diode array dosimetry systems to setup error for quality assurance (QA) of volumetric-modulated arc therapy (VMAT).

    PubMed

    Li, Guangjun; Bai, Sen; Chen, Nianyong; Henderson, Lansdale; Wu, Kui; Xiao, Jianghong; Zhang, Yingjie; Jiang, Qingfeng; Jiang, Xiaoqin

    2013-09-06

    The purpose of this study is to evaluate the sensitivities of 3D diode arrays to setup error for patient-specific quality assurance (QA) of volumetric-modulated arc therapy (VMAT). Translational setup errors of ± 1, ± 2, and ± 3 mm in the RL, SI, and AP directions and rotational setup errors of ± 1° and ± 2° in the pitch, roll, and yaw directions were set up in two phantom systems, ArcCHECK and Delta4, with VMAT plans for 11 patients. Cone-beam computed tomography (CBCT) followed by automatic correction using a HexaPOD 6D treatment couch ensured the position accuracy. Dose distributions of the two phantoms were compared in order to evaluate the agreement between calculated and measured values by using γ analysis with 3%/3 mm, 3%/2 mm, and 2%/2 mm criteria. To determine the impact on setup error for VMAT QA, we evaluated the sensitivity of results acquired by both 3D diode array systems to setup errors in translation and rotation. For the VMAT QA of all patients, the pass rate with the 3%/3 mm criteria exceeded 95% using either phantom. For setup errors of 3 mm and 2°, respectively, the pass rates with the 3%/3mm criteria decreased by a maximum of 14.0% and 23.5% using ArcCHECK, and 14.4% and 5.0% using Delta4. Both systems are sensitive to setup error, and do not have mechanisms to account for setup errors in the software. The sensitivity of both VMAT QA systems was strongly dependent on the patient-specific plan. The sensitivity of ArcCHECK to the rotational error was higher than that of Delta4. In order to achieve less than 3% mean pass rate reduction of VMAT plan QA with the 3%/3 mm criteria, a setup accuracy of 2 mm/1° and 2 mm/2° is required for ArcCheck and Delta4 devices, respectively. The cumulative effect of the combined 2 mm translational and 1° rotational errors caused 3.8% and 2.4% mean pass rates reduction with 3%/3 mm criteria, respectively, for ArcCHECK and Delta4 systems. For QA of VMAT plans for nasopharyngeal cancer (NPC) using the Arc

  13. β-Ga2O3 solar-blind deep-ultraviolet photodetector based on a four-terminal structure with or without Zener diodes

    NASA Astrophysics Data System (ADS)

    Qian, L. X.; Liu, X. Z.; Sheng, T.; Zhang, W. L.; Li, Y. R.; Lai, P. T.

    2016-04-01

    A four-terminal photodetector was fabricated on the ( 2 ¯ 01 )-dominant β-Ga2O3 thin film which was deposited in a plasma-assisted molecular beam epitaxy system. The suitability of this film for solar-blind DUV detection was proved by its transmission spectra. Moreover, the device operating in a specific voltage-current mode can accurately detect the DUV radiation both qualitatively and quantitatively. Accordingly, a dark/photo voltage ratio of 15 was achieved, which is comparable to that of previously-reported β-Ga2O3 interdigital metal-semiconductor-metal photoconductor. More importantly, the aperture ratio of our proposed device exceeds 80%, nearly doubling that of the conventional interdigital metal-semiconductor-metal devices including photoconductor and Schottky-type photodiode, which can intensively benefit the detection efficiency. Furthermore, it was found the dark/photo voltage ratio was nearly trebled with the assistance of two Zener diodes, and further enhancement can be expected by increasing the operating current and/or adopting Zener diodes with smaller Zener voltage. Therefore, this work provides a promising alternative for solar-blind DUV detection.

  14. Design of optical element combining Fresnel lens with microlens array for uniform light-emitting diode lighting.

    PubMed

    Wang, Guangzhen; Wang, Lili; Li, Fuli; Kong, Depeng

    2012-09-01

    One kind of optical element combining Fresnel lens with microlens array is designed simply for LED lighting based on geometrical optics and nonimaging optics. This design method imposes no restriction on the source intensity pattern. The designed element has compact construction and can produce multiple shapes of illumination distribution. Taking square lighting as an example, tolerance analysis is carried out to determine tolerance limits for applying the element in the assembly process. This element can produce on-axis lighting and off-axis lighting.

  15. Study of ablation and implosion stages in wire arrays using coupled ultraviolet and X-ray probing diagnostics

    SciTech Connect

    Anderson, A. A.; Ivanov, V. V.; Astanovitskiy, A. L.; Wiewior, P. P.; Chalyy, O.; Papp, D.

    2015-11-15

    Star and cylindrical wire arrays were studied using laser probing and X-ray radiography at the 1-MA Zebra pulse power generator at the University of Nevada, Reno. The Leopard laser provided backlighting, producing a laser plasma from a Si target which emitted an X-ray probing pulse at the wavelength of 6.65 Å. A spherically bent quartz crystal imaged the backlit wires onto X-ray film. Laser probing diagnostics at the wavelength of 266 nm included a 3-channel polarimeter for Faraday rotation diagnostic and two-frame laser interferometry with two shearing interferometers to study the evolution of the plasma electron density at the ablation and implosion stages. Dynamics of the plasma density profile in Al wire arrays at the ablation stage were directly studied with interferometry, and expansion of wire cores was measured with X-ray radiography. The magnetic field in the imploding plasma was measured with the Faraday rotation diagnostic, and current was reconstructed.

  16. Study of ablation and implosion stages in wire arrays using coupled ultraviolet and X-ray probing diagnostics

    NASA Astrophysics Data System (ADS)

    Anderson, A. A.; Ivanov, V. V.; Astanovitskiy, A. L.; Papp, D.; Wiewior, P. P.; Chalyy, O.

    2015-11-01

    Star and cylindrical wire arrays were studied using laser probing and X-ray radiography at the 1-MA Zebra pulse power generator at the University of Nevada, Reno. The Leopard laser provided backlighting, producing a laser plasma from a Si target which emitted an X-ray probing pulse at the wavelength of 6.65 Å. A spherically bent quartz crystal imaged the backlit wires onto X-ray film. Laser probing diagnostics at the wavelength of 266 nm included a 3-channel polarimeter for Faraday rotation diagnostic and two-frame laser interferometry with two shearing interferometers to study the evolution of the plasma electron density at the ablation and implosion stages. Dynamics of the plasma density profile in Al wire arrays at the ablation stage were directly studied with interferometry, and expansion of wire cores was measured with X-ray radiography. The magnetic field in the imploding plasma was measured with the Faraday rotation diagnostic, and current was reconstructed.

  17. A novel automated hydrophilic interaction liquid chromatography method using diode-array detector/electrospray ionization tandem mass spectrometry for analysis of sodium risedronate and related degradation products in pharmaceuticals.

    PubMed

    Bertolini, Tiziana; Vicentini, Lorenza; Boschetti, Silvia; Andreatta, Paolo; Gatti, Rita

    2014-10-24

    A simple, sensitive and fast hydrophilic interaction liquid chromatography (HILIC) method using ultraviolet diode-array detector (UV-DAD)/electrospray ionization tandem mass spectrometry was developed for the automated high performance liquid chromatography (HPLC) determination of sodium risedronate (SR) and its degradation products in new pharmaceuticals. The chromatographic separations were performed on Ascentis Express HILIC 2.7μm (150mm×2.1mm, i.d.) stainless steel column (fused core). The mobile phase consisted of formate buffer solution (pH 3.4; 0.03M)/acetonitrile 42:58 and 45:55 (v/v) for granules for oral solution and effervescent tablet analysis, respectively, at a flow-rate of 0.2mL/min, setting the wavelength at 262nm. Stability characteristics of SR were evaluated by performing stress test studies. The main degradation product formed under oxidation conditions corresponding to sodium hydrogen (1-hydroxy-2-(1-oxidopyridin-3-yl)-1-phosphonoethyl)phosphonate was characterized by high performance liquid chromatography-electrospray ionization-mass tandem mass spectrometry (HPLC-ESI-MS/MS). The validation parameters such as linearity, sensitivity, accuracy, precision and selectivity were found to be highly satisfactory. Linear responses were observed in standard and in fortified placebo solutions. Intra-day precision (relative standard deviation, RSD) was ≤1.1% for peak area and ≤0.2% for retention times (tR) without significant differences between intra- and inter-day data. Recovery studies showed good results for all the examined compounds (from 98.7 to 101.0%) with RSD ranging from 0.6 to 0.7%. The limits of detection (LOD) and quantitation (LOQ) were 1 and 3ng/mL, respectively. The high stability of standard and sample solutions at room temperature means an undoubted advantage of the method allowing the simultaneous preparation of many samples and consecutive chromatographic analyses by using an autosampler. The developed stability indicating

  18. Quantitative analysis of mycosporine-like amino acids in marine algae by capillary electrophoresis with diode-array detection.

    PubMed

    Hartmann, Anja; Murauer, Adele; Ganzera, Markus

    2017-05-10

    Marine species have evolved a variety of physical or chemical strategies to diminish damage from elevated environmental ultraviolet radiation. Mycosporine-like amino acids, a group of widely distributed small water soluble compounds, are biologically relevant because of their photo-protective potential. In addition, presumed antioxidant and skin protective strategies raise the interest for possible medicinal and cosmetic applications. In this study the first CE method for the quantification of mycosporine-like amino acids in marine species is presented. A borate buffer system consisting of 30mM sodium tetraborate in water at a pH-value of 10.3 enabled the baseline separation of five MAAs, namely palythine, mycosporine-serinol, asterina-330, shinorine and porphyra-334, in 27min. Separation voltage, temperature and detection wavelength were 25kV, 25°C and 320nm, respectively. The optimized method was fully validated and applied for the quantitative determination of MAAs in the marine macroalgae Palmaria palmata, Porphyra umbilicalis, and Porphyra sp., as well as the lichen Lichina pygmaea.

  19. Direct writing of micro/nano-scale patterns by means of particle lens arrays scanned by a focused diode pumped Nd:YVO4 laser

    NASA Astrophysics Data System (ADS)

    Pena, Ana; Wang, Zengbo; Whitehead, David; Li, Lin

    2010-11-01

    A practical approach to a well-known technique of laser micro/nano-patterning by optical near fields is presented. It is based on surface patterning by scanning a Gaussian laser beam through a self-assembled monolayer of silica micro-spheres on a single-crystalline silicon (Si) substrate. So far, the outcome of this kind of near-field patterning has been related to the simultaneous, parallel surface-structuring of large areas either by top hat or Gaussian laser intensity distributions. We attempt to explore the possibility of using the same technique in order to produce single, direct writing of features. This could be of advantage for applications in which only some areas need to be patterned (i.e. local area selective patterning) or single lines are required (e.g. a particular micro/nano-fluidic channel). A diode pumped Nd:YVO4 laser system (wavelength of 532 nm, pulse duration of 8 ns, repetition rate of 30 kHz) with a computer-controlled 3 axis galvanometer beam scanner was employed to write user-defined patterns through the particle lens array on the Si substrate. After laser irradiation, the obtained patterns which are in the micro-scale were composed of sub-micro/micro-holes or bumps. The micro-pattern resolution depends on the dimension of both the micro-sphere’s diameter and the beam’s spot size. The developed technique could potentially be employed to fabricate photonic crystal structures mimicking nature’s butterfly wings and anti-reflective “moth eye” arrays for photovoltaic cells.

  20. Extraction and Quantification of Tryptophan and Kynurenine from Cultured Cells and Media Using a High Performance Liquid Chromatography (HPLC) System Equipped with an Ultra-Sensitive Diode Array Detector

    PubMed Central

    Kim, Jeffrey; Stewart, Benjamin; Weiss, Robert H

    2016-01-01

    Evidence of the involvement of tryptophan and its metabolite, kynurenine, in various biological processes including cancer is constantly expanding. Analysis of cell extracts and culture media can allow for quick snapshots of the metabolic fluctuations occurring in vitro. Here, we describe a method for metabolite extraction from mammalian cells and analysis of extracted metabolites and cell culture media by HPLC with detection using an ultra-sensitive diode array detector. PMID:27213172

  1. Characterization of an Optical Device with an Array of Blue Light Emitting Diodes LEDS for Treatment of Neonatal Jaundice.

    NASA Astrophysics Data System (ADS)

    Sebbe, Priscilla Fróes; Villaverde, Antonio G. J. Balbin; Nicolau, Renata Amadei; Barbosa, Ana Maria; Veissid, Nelson

    2008-04-01

    Phototherapy is a treatment that consists in irradiating a patient with light of high intensity, which promotes beneficial photochemical transformations in the irradiated area. The phototherapy for neonates is applied to break down the bilirubin, an organic pigment that is a sub product of the erythrocytes degradation, and to increase its excretion by the organism. Neonates should be irradiated with light of wavelength that the bilirubin can absorb, and with spectral irradiances between 4 and 16 μW/cm2/nm. The efficiency of the treatment depends on the irradiance and the area of the body that is irradiated. A convenient source of light for treatment of neonatal jaundice is the blue Light Emitter Diode (LED), emitting in the range of 400 to 500 nm, with power of the order of 10-150 mW. Some of the advantages for using LEDS are: low cost, operating long lifetime (over 100,000 hours), narrow emission linewith, low voltage power supply requirement and low heating. The aim of this work was to build and characterize a device for phototherapy treatment of neonatal jaundice. This consists of a blanket with 88 blue LEDs (emission peak at 472 nm), arranged in an 8×11 matrix, all connected in parallel and powered by a 5V-2A power supply. The device was characterized by using a spectroradiometer USB2000 (Ocean Optics Inc, USA), with a sensitivity range of 339-1019 nm. For determination of light spatial uniformity was used a calibrated photovoltaic sensor for measuring light intensity and mapping of the light intensity spatial distribution. Results indicate that our device shows a uniform spatial distribution for distances from the blanket larger than 10 cm, with a maximum of irradiance at such a distance. This device presenting a large and uniform area of irradiation, efficient wavelength emission and high irradiance seems to be promising for neonates' phototherapy treatment.

  2. Multi-section core-shell InGaN/GaN quantum-well nanorod light-emitting diode array.

    PubMed

    Tu, Charng-Gan; Yao, Yu-Feng; Liao, Che-Hao; Su, Chia-Ying; Hsieh, Chieh; Weng, Chi-Ming; Lin, Chun-Han; Chen, Hao-Tsung; Kiang, Yean-Woei; Yang, C C

    2015-08-24

    The growth of a two-section, core-shell, InGaN/GaN quantum-well (QW) nanorod- (NR-) array light-emitting diode device based on a pulsed growth technique with metalorganic chemical vapor deposition is demonstrated. A two-section n-GaN NR is grown through a tapering process for forming two uniform NR sections of different cross-sectional sizes. The cathodoluminescence (CL), photoluminescence (PL), and electrolumines-cence (EL) characterization results of the two-section NR structure are compared with those of a single-section NR sample, which is prepared under the similar condition to that for the first uniform NR section of the two-section sample. All the CL, PL, and EL spectra of the two-section sample (peaked between 520 and 525 nm) are red-shifted from those of the single-section sample (peaked around 490 nm) by >30 nm in wavelength. Also, the emitted spectral widths of the two-section sample become significantly larger than their counterparts of the single-section sample. The PL spectral full-width at half-maximum increases from ~37 to ~61 nm. Such variations are attributed to the higher indium incorporation in the sidewall QWs of the two-section sample due to the stronger strain relaxation in an NR section of a smaller cross-sectional size and the more constituent atom supply from the larger gap volume between neighboring NRs.

  3. High-performance anion-exchange chromatography coupled with diode array detection for the determination of dencichine in Panax notoginseng and related species.

    PubMed

    Qiao, Chun-Feng; Liu, Xiao-Mei; Cui, Xiu-Ming; Hu, De-Jun; Chen, Yi-Wen; Zhao, Jing; Li, Shao-Ping

    2013-08-01

    A high-performance anion-exchange chromatography coupled with diode array detection method was developed for the determination of dencichine in Panax notoginseng and related species. The analysis was performed on an Eprogen Synchropak WAX column (4.6 × 250 mm, 6 μm) with 50 mM NaH2 PO4 aqueous solution isocratic elution. The method was validated in terms of linearity, sensitivity, precision, stability, and accuracy. It was found that the calibration curve for dencichine showed good linearity (R(2) = 0.9999) within the test range. The LOD and LOQ were 0.77 and 3.06 ng, respectively. The RSD for intra- and interday repeatability was 0.2 and 0.5%, respectively. The test solution of dencichine is stable at least for three days at room temperature and for seven days at 4 °C. The mean recovery of dencichine was 102.0%. The established method was successfully applied to determine dencichine in the raw root of P. nogoginseng, P. ginseng, and P. quinquefolium as well as the steamed root of P. notoginseng. Compared with previous reports, this method is sensitive, selective, and accurate, which is helpful to evaluate the quality of P. notoginseng and related species.

  4. Rapid quantitative analysis of individual anthocyanin content based on high-performance liquid chromatography with diode array detection with the pH differential method.

    PubMed

    Wang, Huayin

    2014-09-01

    A new quantitative technique for the simultaneous quantification of the individual anthocyanins based on the pH differential method and high-performance liquid chromatography with diode array detection is proposed in this paper. The six individual anthocyanins (cyanidin 3-glucoside, cyanidin 3-rutinoside, petunidin 3-glucoside, petunidin 3-rutinoside, and malvidin 3-rutinoside) from mulberry (Morus rubra) and Liriope platyphylla were used for demonstration and validation. The elution of anthocyanins was performed using a C18 column with stepwise gradient elution and individual anthocyanins were identified by high-performance liquid chromatography with tandem mass spectrometry. Based on the pH differential method, the high-performance liquid chromatography peak areas of maximum and reference absorption wavelengths of anthocyanin extracts were conducted to quantify individual anthocyanins. The calibration curves for these anthocyanins were linear within the range of 10-5500 mg/L. The correlation coefficients (r(2)) all exceeded 0.9972, and the limits of detection were in the range of 1-4 mg/L at a signal-to-noise ratio ≥5 for these anthocyanins. The proposed quantitative analysis was reproducible with good accuracy of all individual anthocyanins ranging from 96.3 to 104.2% and relative recoveries were in the range 98.4-103.2%. The proposed technique is performed without anthocyanin standards and is a simple, rapid, accurate, and economical method to determine individual anthocyanin contents.

  5. Fast and simultaneous determination of 12 polyphenols in apple peel and pulp by using chemometrics-assisted high-performance liquid chromatography with diode array detection.

    PubMed

    Wang, Tong; Wu, Hai-Long; Xie, Li-Xia; Zhu, Li; Liu, Zhi; Sun, Xiao-Dong; Xiao, Rong; Yu, Ru-Qin

    2017-02-20

    In this work, a smart chemometrics-enhanced strategy, high-performance liquid chromatography, and diode array detection coupled with second-order calibration method based on alternating trilinear decomposition algorithm was proposed to simultaneously quantify 12 polyphenols in different kinds of apple peel and pulp samples. The proposed strategy proved to be a powerful tool to solve the problems of coelution, unknown interferences, and chromatographic shifts in the process of high-performance liquid chromatography analysis, making it possible for the determination of 12 polyphenols in complex apple matrices within 10 min under simple conditions of elution. The average recoveries with standard deviations, and figures of merit including sensitivity, selectivity, limit of detection, and limit of quantitation were calculated to validate the accuracy of the proposed method. Compared to the quantitative analysis results from the classic high-performance liquid chromatography method, the statistical and graphical analysis showed that our proposed strategy obtained more reliable results. All results indicated that our proposed method used in the quantitative analysis of apple polyphenols was an accurate, fast, universal, simple, and green one, and it was expected to be developed as an attractive alternative method for simultaneous determination of multitargeted analytes in complex matrices.

  6. Ionic liquids for improving the extraction of NSAIDs in water samples using dispersive liquid-liquid microextraction by high performance liquid chromatography-diode array-fluorescence detection.

    PubMed

    Toledo-Neira, Carla; Álvarez-Lueje, Alejandro

    2015-03-01

    A rapid, sensitive and efficient analytical method based on the use of ionic liquids for determination of non-steroidal anti-inflammatory drugs (NSAIDs) in water samples was developed. High-performance liquid chromatography equipped with a diode array and fluorescence detector was used for quantification of ketoprofen, ibuprofen and diclofenac in tap and river water samples. This new method relies on the use of two ionic liquids with multiple functionalities: one functions as an extraction solvent (1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), and the other changes the polarity in the aqueous medium (1-butyl-3-methylimidazolium tetrafluoroborate, ([BMIM][BF4]). Factors such as the type and volume of the ILs and dispersive solvent, sample volume, and centrifugation time were investigated and optimized. The optimized method exhibited good precision, with relative standard deviation values between 2% and 3%, for the three NSAIDs. Limits of detection achieved for all of the analytes were between 17 and 95 ng mL(-1), and the recoveries ranged from 89% to 103%. Furthermore, the enrichment factors ranged from 49 to 57. The proposed method was successfully applied to the analysis of NSAIDs in tap and river water samples.

  7. Chemometrics-assisted high performance liquid chromatography-diode array detection strategy to solve varying interfering patterns from different chromatographic columns and sample matrices for beverage analysis.

    PubMed

    Yin, Xiao-Li; Wu, Hai-Long; Gu, Hui-Wen; Hu, Yong; Wang, Li; Xia, Hui; Xiang, Shou-Xia; Yu, Ru-Qin

    2016-02-26

    This work reports a chemometrics-assisted high performance liquid chromatography-diode array detection (HPLC-DAD) strategy to solve varying interfering patterns from different chromatographic columns and sample matrices for the rapid simultaneous determination of six synthetic colorants in five kinds of beverages with little sample pretreatment. The investigation was performed using two types of LC columns under the same elution conditions. Although analytes using different columns have different co-elution patterns that appear more seriously in complex backgrounds, all colorants were properly resolved by alternating trilinear decomposition (ATLD) method and accurate chromatographic elution profiles, spectral profiles as well as relative concentrations were obtained. The results were confirmed by those obtained from traditional HPLC-UV method at a particular wavelength and the results of both methods were consistent with each other. All results demonstrated that the proposed chemometrics-assisted HPLC-DAD method is accurate, economical and universal, and can be promisingly applied to solve varying interfering patterns from different chromatographic columns and sample matrices for the analysis of complex food samples.

  8. Quantitative analysis of the eight major compounds in the Samsoeum using a high-performance liquid chromatography coupled with diode array detection and electrospray ionization mass spectrometer

    PubMed Central

    Weon, Jin Bae; Yang, Hye Jin; Lee, Bohyoung; Ma, Jin Yeul; Ma, Choong Je

    2015-01-01

    Background: Samsoeum was traditionally used for treatment of a respiratory disease. Objective: The simultaneous determination of eight major compounds, ginsenoside Rg3, caffeic acid, puerarin, costunolide, hesperidin, naringin, glycyrrhizin, and 6-gingerol in the Samsoeum using a high-performance liquid chromatography (HPLC) coupled with diode array detection (DAD) and an electrospray ionization mass spectrometer was developed for an accurate and reliable quality assessment. Materials and Methods: Eight compounds were qualitative identified based on their mass spectra and by comparing with standard compounds and quantitative analyzed by HPLC-DAD. Separation of eight compounds was carried out on a LUNA C18 column (S-5 μm, 4.6 mm i.d. ×250 mm) with gradient elution composed of acetonitrile and 0.1% trifluoroacetic acid. Results: The data showed good linearity (R2 > 0.9996). The limits of detection and the limits of quantification were <0.53 μg and 1.62 μg, respectively. Inter- and Intra-day precisions (expressed as relative standard deviation values) were within 1.94% and 1.91%, respectively. The recovery of the method was in the range of 94.24–107.90%. Conclusion: The established method is effective and could be applied to quality control of Samsoeum. PMID:25829771

  9. Rapid and simple method for the determination of emodin in tartary buckwheat (Fagopyrum tataricum) by high-performance liquid chromatography coupled to a diode array detector.

    PubMed

    Peng, Lian-Xin; Wang, Jing-Bo; Hu, Li-Xue; Zhao, Jiang-Lin; Xiang, Da-Bing; Zou, Liang; Zhao, Gang

    2013-01-30

    A simple and rapid method for determining emodin, an active factor presented in tartary buckwheat (Fagopyrum tataricum), by high-performance liquid chromatography coupled to a diode array detector (HPLC-DAD) has been developed. Emodin was separated from an extract of buckwheat on a Kromasil-ODS C(18) (250 mm × 4.6 mm × 5 μm) column. The separation is achieved within 15 min on the ODS column. Emodin can be quantified using an external standard method detecting at 436 nm. Good linearity is obtained with a correlation coefficient exceeding 0.9992. The limit of detection and the limit of quantification are 5.7 and 19 μg/L, respectively. This method shows good reproducibility for the quantification of the emodin with a relative standard deviation value of 4.3%. Under optimized extraction conditions, the recovery of emodin was calculated as >90%. The validated method is successfully applied to quantify the emodin in tartary buckwheat and its products.

  10. Simultaneous quantitative determination of six active components in traditional Chinese medicinal preparation Cerebralcare Granule® by RP-HPLC coupled with diode array detection for quality control.

    PubMed

    Wang, Xiang-yang; Ma, Xiao-hui; Li, Wei; Chu, Yang; Guo, Jia-hua; Zhou, Shui-ping; Zhu, Yong-hong

    2014-09-01

    A simple, accurate and reliable method for the simultaneous separation and determination of six active components (protocatechuic acid, chlorogenic acid, caffeic acid, paeoniflorin, ferulic acid and rosmarinic acid) in traditional Chinese medicinal preparation Cerebralcare Granule(®) (CG) was developed using reverse-phase high-performance liquid chromatography coupled with diode array detector detection. The chromatographic separation was performed on a Hypersil GOLD C18 column with aqueous formic acid (0.1%, v/v) and acetonitrile as mobile phase at a flow rate of 0.2 ml/min at 30 °C. Because of the different UV characteristics of these components, change detection wavelength method was used for quantitative analysis. All of the analytes showed good linearity (r > 0.9992). The established method showed good precision and relative standard deviations (%) for intra-day and inter-day variations of 0.15-1.81 and 0.11-1.98%, respectively. The validated method was successfully applied to the simultaneously determination of six active components in CG from different batches.

  11. Development of a method for the analysis of drugs of abuse in vitreous humor by capillary electrophoresis with diode array detection (CE-DAD).

    PubMed

    Costa, Jose Luiz; Morrone, Andre Ribeiro; Resende, Rodrigo Ribeiro; Chasin, Alice Aparecida da Matta; Tavares, Marina Franco Maggi

    2014-01-15

    This work presents the development of an analytical method based on capillary electrophoresis with diode array detection for the analysis of drugs of abuse and biotransformation products in vitreous humor. Composition of the background electrolyte, implementation of an online pre-concentration strategy and sample preparation procedures were objects of study. The complete electrophoretic separation of 12 analytes (amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyethylamphetamine (MDEA), ketamine, cocaine, cocaethylene, lidocaine, morphine, 6-monoacetylmorphine and heroin) and the internal standard N-methyl-1-(3,4-methylenedioxyphenyl)-2-butamine (MBDB) was obtained within 13min of run. The method was validated presenting good linearity (r(2)>0.99), recovery ≥90%, precision better than 12% RSD and acceptable accuracy in the range of 86-118% at three concentration levels (50, 100 and 500ng/mL). LODs and LOQs in the order of 1-5ng/mL and 5-10ng/mL, respectively, were obtained. After validation, the method was applied to eighty-seven vitreous humor samples and the results were compared to those obtained by a liquid chromatography tandem mass spectrometry (LC-MS/MS) screening method, routinely used by the forensic toxicology laboratory of the Sao Paulo State Police, Brazil. Cocaine was detected in 7.1%, cocaethylene in 3.6%, lidocaine in 2.4% and ketamine in 1.2% of the total number of analyzed samples.

  12. Dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography-diode array detection for the determination of N-methyl carbamate pesticides in vegetables.

    PubMed

    Lin, Xiangyun; Chen, Xiaohui; Huo, Xin; Yu, Zhiguo; Bi, Kaishun; Li, Qing

    2011-01-01

    This paper described a simple, rapid and efficient method for the determination of N-methyl carbamate pesticides in tomato, cucumber, carrot and lettuce samples by dispersive liquid-liquid microextraction coupled with HPLC-diode array detection. Some experimental parameters that influenced the extraction efficiency, such as types and volumes of extraction and disperser solvents, extraction time and salt effect were examined and optimized. Under optimum conditions, the LOD of the method were 0.5-3.0 μg/kg depending on the compounds and the kind of vegetables. The linearities of the method were obtained in the range of 10.0-300 μg/kg for aldicarb, MTMC, carbofuran and carbaryl, and 20.0-600 μg/kg for isoprocarb, with the correlation coefficients ranging from 0.9921 to 0.9993. The RSD varied from 2.9 to 7.5% (n=5). The recoveries of the method for the five carbamates from vegetable samples at two different spiking levels were ranged from 77.8 to 98.2%. Results showed that the method we proposed can meet the requirements for the determination of N-methyl carbamate in vegetable samples and was finally applied to the analysis of target pesticides in vegetable samples taken from local markets.

  13. Characterization of constituents in Stellera chamaejasme L. by rapid-resolution liquid chromatography-diode array detection and electrospray ionization time-of-flight mass spectrometry.

    PubMed

    Zhao, Liang; Lou, Zi-Yang; Zhu, Zhen-Yu; Zhang, Guo-Qing; Chai, Yi-Feng

    2008-01-01

    A reliable and rapid method based on rapid-resolution liquid chromatography-diode array detection (RRLC-DAD) and electrospray ionization time-of-flight mass spectrometry (ESI-TOF/MS) has been developed for the isolation and characterization of multiple constituents in the root of Stellera chamaejasme L., which was extracted by sonication with methanol in an optimized procedure. Separation of the multiple constituents was achieved on an Agilent Zorbax XDB-C18 (50x3.0 mm i.d.; 1.8 microm) column using a gradient elution at a flow rate of 0.4 mL/min. The detection wavelength was 210 nm. Mass spectra were acquired in both positive and negative modes. A formula database of the known chemical constituents in the root of Stellera chamaejasme L. was established by an Agilent software. Twenty-two obvious peaks appeared in the total ion chromatogram and nine of them were characterized by TOF/MS. The RRLC-DAD and ESI-TOF/MS method with ultrasonic extraction would be useful for rapid and effective characterization of chemical constituents in the root of Stellera chamaejasme L.

  14. Direct identification of phenolic constituents in Boldo Folium (Peumus boldus Mol.) infusions by high-performance liquid chromatography with diode array detection and electrospray ionization tandem mass spectrometry.

    PubMed

    Simirgiotis, M J; Schmeda-Hirschmann, G

    2010-01-22

    A very simple and direct method was developed for the qualitative analysis of polyphenols in boldo (Peumus boldus Mol., Monimiaceae) leaves infusions by high-performance liquid chromatography with diode array detection (HPLC-DAD) and electrospray ionization tandem mass spectrometry (HPLC-MS(n)). The phenolic constituents identified in infusions of the crude drug Boldo Folium were mainly proanthocyanidins and flavonol glycosides. In the infusions, 41 compounds were detected in male and 43 compounds in female leaf samples, respectively. Nine quercetin glycosides, eight kaempferol derivatives, nine isorhamnetin glycosides, three phenolic acids, one caffeoylquinic acid glycoside and twenty one proanthocyanidins were identified by HPLC-DAD and ESI-MS for the first time in the crude drug. Isorhamnetin glucosyl-di-rhamnoside was the most abundant flavonol glycoside in the male boldo sample, whereas isorhamnetin di-glucosyl-di-rhamnoside was the main phenolic compound in female boldo leaves infusion. The results suggest that the medicinal properties reported for this popular infusion should be attributed not only to the presence of catechin and boldine but also to several phenolic compounds with known antioxidant activity. The HPLC fingerprint obtained can be useful in the authentication of the crude drug Boldo Folium as well as for qualitative analysis and differentiation of plant populations in the tree distribution range.

  15. Determination of chloroacetanilide herbicide metabolites in water using high-performance liquid chromatography-diode array detection and high-performance liquid chromatography/mass spectrometry

    USGS Publications Warehouse

    Hostetler, K.A.; Thurman, E.M.

    2000-01-01

    Analytical methods using high-performance liquid chromatography-diode array detection (HPLC-DAD) and high-performance liquid chromatography/mass spectrometry (HPLC/MS) were developed for the analysis of the following chloroacetanilide herbicide metabolites in water: alachlor ethanesulfonic acid (ESA); alachlor oxanilic acid; acetochlor ESA; acetochlor oxanilic acid; metolachlor ESA; and metolachlor oxanilic acid. Good precision and accuracy were demonstrated for both the HPLC-DAD and HPLC/MS methods in reagent water, surface water, and ground water. The average HPLC-DAD recoveries of the chloroacetanilide herbicide metabolites from water samples spiked at 0.25, 0.5 and 2.0 ??g/l ranged from 84 to 112%, with relative standard deviations of 18% or less. The average HPLC/MS recoveries of the metabolites from water samples spiked at 0.05, 0.2 and 2.0 ??g/l ranged from 81 to 118%, with relative standard deviations of 20% or less. The limit of quantitation (LOQ) for all metabolites using the HPLC-DAD method was 0.20 ??g/l, whereas the LOQ using the HPLC/MS method was at 0.05 ??g/l. These metabolite-determination methods are valuable for acquiring information about water quality and the fate and transport of the parent chloroacetanilide herbicides in water. Copyright (C) 2000 Elsevier Science B.V.

  16. Qualitative and quantitative analysis of an alkaloid fraction from Piper longum L. using ultra-high performance liquid chromatography-diode array detector-electrospray ionization mass spectrometry.

    PubMed

    Li, Kuiyong; Fan, Yunpeng; Wang, Hui; Fu, Qing; Jin, Yu; Liang, Xinmiao

    2015-05-10

    In a previous research, an alkaloid fraction and 18 alkaloid compounds were prepared from Piper longum L. by series of purification process. In this paper, a qualitative and quantitative analysis method using ultra-high performance liquid chromatography-diode array detector-mass spectrometry (UHPLC-DAD-MS) was developed to evaluate the alkaloid fraction. Qualitative analysis of the alkaloid fraction was firstly completed by UHPLC-DAD method and 18 amide alkaloid compounds were identified. A further qualitative analysis of the alkaloid fraction was accomplished by UHPLC-MS/MS method. Another 25 amide alkaloids were identified according to their characteristic ions and neutral losses. At last, a quantitative method for the alkaloid fraction was established using four marker compounds including piperine, pipernonatine, guineensine and N-isobutyl-2E,4E-octadecadienamide. After the validation of this method, the contents of above four marker compounds in the alkaloid fraction were 57.5mg/g, 65.6mg/g, 17.7mg/g and 23.9mg/g, respectively. Moreover, the relative response factors of other three compounds to piperine were calculated. A comparative study between external standard quantification and relative response factor quantification proved no remarkable difference. UHPLC-DAD-MS method was demonstrated to be a powerful tool for the characterization of the alkaloid fraction from P. longum L. and the result proved that the quality of alkaloid fraction was efficiently improved after appropriate purification.

  17. Identification of protein binders in works of art by high-performance liquid chromatography-diode array detector analysis of their tryptic digests.

    PubMed

    Fremout, Wim; Sanyova, Jana; Saverwyns, Steven; Vandenabeele, Peter; Moens, Luc

    2009-04-01

    Proteins in works of art are generally determined by the relative amounts of amino acids. This method, however, implies a loss of information on the protein structure and its modifications. Consequently, we propose a method based on the analysis of trypsin digests using high-performance liquid chromatography (HPLC) UV diode array detection (DAD) for painting binder studies. All reaction steps are done in the same vial; no extraction methods or sample transfer is needed, reducing the risk of sample losses. A collection of pure binders (collagen, ovalbumin, yolk and casein) as well as homemade and historical paint samples have been investigated with this method. Chromatograms of unknowns at 214 nm and 280 nm are compared with those of the reference samples as a fingerprint. There is a good agreement between many peptides, but others seem to have been lost or their retention time shifted due to small compositional changes because of ageing and degradation of the paint. The results are comparable with the results of other techniques used for binder identification on the same samples, with the additional advantage of differentiation between egg yolk and glair.

  18. Simultaneous determination of six synthetic phenolic antioxidants in edible oils using dispersive liquid-liquid microextraction followed by high-performance liquid chromatography with diode array detection.

    PubMed

    Xu, Shuangjiao; Liu, Liangliang; Wang, Yanqin; Zhou, Dayun; Kuang, Meng; Fang, Dan; Yang, Weihua; Wei, Shoujun; Xiao, Aiping; Ma, Lei

    2016-08-01

    A simple, rapid, organic-solvent- and sample-saving pretreatment technique, called dispersive liquid-liquid microextraction, was developed for the determination of six synthetic phenolic antioxidants from edible oils before high-performance liquid chromatography with diode array detection. The entire procedure was composed of a two-step microextraction and a centrifugal process and could be finished in about 5 min, only consuming only 25 mg of sample and 1 mL of the organic solvent for each extraction. The influences of several important parameters on the microextraction efficiency were thoroughly investigated. Recovery assays for oil samples were spiked at three concentration levels, 50, 100 and 200 mg/kg, and provided recoveries in the 86.3-102.5% range with a relative standard deviation below 3.5%. The intra-day and inter-day precisions for the analysis were less than 3.8%. The proposed method was successfully applied for the determination of synthetic phenolic antioxidants in different oil samples, and satisfactory results were obtained. Thus, the developed method represents a viable alternative for the quality control of synthetic phenolic antioxidant concentrations in edible oils.

  19. Three-dimensional mesoscale heterostructures of ZnO nanowire arrays epitaxially grown on CuGaO2 nanoplates as individual diodes.

    PubMed

    Forticaux, Audrey; Hacialioglu, Salih; DeGrave, John P; Dziedzic, Rafal; Jin, Song

    2013-09-24

    We report a three-dimensional (3D) mesoscale heterostructure composed of one-dimensional (1D) nanowire (NW) arrays epitaxially grown on two-dimensional (2D) nanoplates. Specifically, three facile syntheses are developed to assemble vertical ZnO NWs on CuGaO2 (CGO) nanoplates in mild aqueous solution conditions. The key to the successful 3D mesoscale integration is the preferential nucleation and heteroepitaxial growth of ZnO NWs on the CGO nanoplates. Using transmission electron microscopy, heteroepitaxy was found between the basal planes of CGO nanoplates and ZnO NWs, which are their respective (001) crystallographic planes, by the observation of a hexagonal Moiré fringes pattern resulting from the slight mismatch between the c planes of ZnO and CGO. Careful analysis shows that this pattern can be described by a hexagonal supercell with a lattice parameter of almost exactly 11 and 12 times the a lattice constants for ZnO and CGO, respectively. The electrical properties of the individual CGO-ZnO mesoscale heterostructures were measured using a current-sensing atomic force microscopy setup to confirm the rectifying p-n diode behavior expected from the band alignment of p-type CGO and n-type ZnO wide band gap semiconductors. These 3D mesoscale heterostructures represent a new motif in nanoassembly for the integration of nanomaterials into functional devices with potential applications in electronics, photonics, and energy.

  20. Rapid separation and determination of process-related substances of paracetamol using reversed-phase HPLC with photo diode array as a detector.

    PubMed

    Rao, R Nageswara; Narasaraju, A

    2006-02-01

    A simple and rapid gradient reversed-phase high-performance liquid chromatographic method for simultaneous separation and determination of paracetamol and its related compounds in bulk drugs and pharmaceutical formulations has been developed. As many as nine process impurities and one degradation product of paracetamol have been separated on a Symmetry C18 column (4.6 x 250 mm i.d., particle size 5 microm) with gradient elution using 0.01 M potassium dihydrogen phosphate buffer (pH 3.0) and acetonitrile as mobile phase and photo diode array detection at 215 nm. The chromatographic behavior of all the compounds was examined under variable compositions of different solvents, temperatures, buffer concentrations and pH values. The correlation coefficients for calibration curves for paracetamol as well as impurities were in the range of 0.9951 - 0.9994. The proposed RP-LC method was successfully applied to the analysis of commercial formulations; the recoveries of paracetamol were in the range of 99-101%. The method could be of use not only for rapid and routine evaluation of the quality of paracetamol in bulk drug manufacturing units but also for detection of its impurities in pharmaceutical formulations.

  1. Metabolite profiling of licorice (Glycyrrhiza glabra) from different locations using comprehensive two-dimensional liquid chromatography coupled to diode array and tandem mass spectrometry detection.

    PubMed

    Montero, Lidia; Ibáñez, Elena; Russo, Mariateresa; di Sanzo, Rosa; Rastrelli, Luca; Piccinelli, Anna Lisa; Celano, Rita; Cifuentes, Alejandro; Herrero, Miguel

    2016-03-24

    Profiling of the main metabolites from several licorice (Glycyrrhiza glabra) samples collected at different locations is carried out in this work by using comprehensive two-dimensional liquid chromatography (LC × LC) coupled to diode array (DAD) and mass spectrometry (MS) detectors. The optimized method was based on the application of a HILIC-based separation in the first dimension combined with fast RP-based second dimension separation. This set-up was shown to possess powerful separation capabilities allowing separating as much as 89 different metabolites in a single sample. Identification and grouping of metabolites according to their chemical class were achieved using the DAD, MS and MS/MS data. Triterpene saponins were the most abundant metabolites followed by glycosylated flavanones and chalcones, whereas glycyrrhizic acid, as expected, was confirmed as the main component in all the studied samples. LC × LC-DAD-MS/MS was able to resolve these complex licorice samples providing with specific metabolite profiles to the different licorice samples depending on their geographical origin. Namely, from 19 to 50 specific compounds were exclusively determined in the 2D-chromatograms from the different licorice samples depending on their geographical origin, which can be used as a typical pattern that could potentially be related to their geographical location and authentication.

  2. Simple, cost-effective and sensitive liquid chromatography diode array detector method for simultaneous determination of eight sulfonylurea herbicides in soya milk samples.

    PubMed

    Rejczak, Tomasz; Tuzimski, Tomasz

    2016-11-18

    In this study authors propose a simple, cost-effective and sensitive liquid chromatography diode array detector (HPLC-DAD) method for the simultaneous determination of eight sulfonylurea herbicides (oxasulfuron, metsulfuron-methyl, triasulfuron, rimsulfuron, chlorsulfuron, mesosulfuron-methyl, amidosulfuron and bensulfuron-methyl) in soya milk samples. QuEChERS-based extraction procedure presents good performance for all of the analytes with recoveries in the range of 61-108% and relative standard deviations (RSD%) less than 15%. No significant matrix effect was observed thanks to application of effective zirconium-dioxide based sorbent (Z-Sep). Method LOQs for all investigated analytes were set at satisfactory low value of 10ngmL(-1) of food product. The procedure was evaluated in terms of natural samples analysis. Chlorsulfuron was determined at concentration of 14.2ngmL(-1) of soya milk product, which was qualitatively confirmed via LC coupled with tandem mass spectrometry (LC-MS/MS). The most important steps of procedure optimization are presented.

  3. Simultaneous determination of five marker compounds in Xuanfu Daizhe Tang by high-performance liquid chromatography coupled with diode array detection for quality control

    PubMed Central

    Qin, Kunming; Wang, Bin; Cai, Hao; Li, Weidong; Yao, Zhongqing; Zhang, Xingde; Lu, Tulin; Cai, Baochang

    2012-01-01

    Background: Xuanfu Daizhe Tang (XDT) is a classical traditional Chinese medicinal prescription that has been widely used for treating digestive system illnesses for hundreds of years. Materials and Methods: In this study, a simple and sensitive high-performance liquid chromatography coupled with diode array detection (HPLC-DAD) method was established for the simultaneous determination of five marker compounds in XDT including chlorogenic acid, glycyrrhizic acid, ginsenoside Rg1, ginsenoside Rb1 and ginsenoside Re, for quality control of this well-known traditional Chinese medicine (TCM). Results: These compounds were separated in less than 130 min using a YMC C18 column with a gradient elution system of acetonitrile and 0.1% phosphoric acid water solution at a flow rate of 1 ml/min. All calibration curves of standard components showed good linearity with R2 >0.9991. Limit of detection and limit of quantification varied from 0.11 to 4.3 μg/ml and 0.20 to 11.6 μg/ml, respectively. The relative standard deviations (RSDs) of the intra-day and inter-day experiments were less than 4.72 and 5.48%, respectively. The accuracy of recovery test ranged from 95.0 to 105.0% with RSD values 1.28- 4.32%. Conclusion: The validated method is simple, reliable, and successfully applied to determine the contents of the selected compounds in XDT for quality control. PMID:24082626

  4. Analysis of opiates, cocaine and metabolites in urine by high-performance liquid chromatography with diode array detection (HPLC-DAD).

    PubMed

    Fernández, P; Vázquez, C; Morales, L; Bermejo, A M

    2005-01-01

    An analytical method is proposed for the simultaneous determination of morphine, codeine, 6-acetyl-morphine (MAM), cocaine, benzoylecgonine (BEG), cocaethylene, methadone and 2-ethylen-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) in urine using high performance liquid chromatography coupled to a diode array detector (HPLC-DAD). The selection of working wavelengths is based on the highest chromatographic response for each component: 233 nm for cocaine, BEG and cocaethylene; 285 nm for morphine, codeine and MAM; and 292 nm for methadone and EDDP. The mobile phase, which is a mixture of acetonitrile and 0.02 M phosphate buffer at pH 6.53, was eluted in gradient mode through an XTerra RP-8 column (250 mm x 4.6 mm i.d., 5 microm particle size). After applying a solid-phase extraction procedure with Bond Elut Certify cartridges, the recoveries obtained were between 60% (EDDP) and 97% (cocaethylene). A good linearity of the method in the 0.1-10 microg mL(-1) range of urinary concentrations was obtained because the coefficient of correlation exceeded 0.99 for each drug. The precision and accuracy were quite good, with values of <7% and within the range +/- 6%, respectively. Finally, the proposed method was applied to 23 urine samples from fatal intoxications related to methadone, heroin and[sol ]or cocaine.

  5. Online screening of nitric oxide scavengers in natural products using high performance liquid chromatography coupled with tandem diode array and fluorescence detection.

    PubMed

    Li, Dapeng; Wang, Ting; Guo, Yujie; Hu, Yuanjia; Yu, Boyang; Qi, Jin

    2015-12-18

    Nitric oxide (NO) is an important cellular signaling molecule with extensive physiological and pathophysiological effects. NO scavengers have the potential to treat inflammation, septic shock and other related diseases, and numerous examples have been chemically synthesized or isolated from natural products. The chemical diversity of natural products, however, means that a huge effort is necessary to efficiently screen and identify bioactive compounds, especially NO scavengers. In this article, we propose an effective analytical method to screen for NO scavengers in three natural products using an online system that couples high performance liquid chromatography with tandem diode array and fluorescence detection (HPLC-DAD-FLD). Eighteen compounds from radix of Scutellaria baicalensis Georgi and green tea displayed significant NO scavenging activity whereas components of Pueraria lobata (Willd.) Ohwi had no discernable activity. The structures of the active compounds were elucidated using Agilent Accurate-Mass Q-TOF LC/MS system. Preliminary analysis of structure-activity relationships indicated that, in flavonoids, a 2,3-double bond and a 3-H atom or a 3-OH group are essential for activity. In tannins, poly-hydroxyl groups are important for NO scavenging activity. Method validation indicated that the newly developed method is both reliable and repeatable. The online method that we present provides a simple, rapid and effective way to identify and characterize NO scavengers present in natural products.

  6. Simultaneous determination of ten bioactive compaounds from the roots of Cynanchum paniculatum by using high performance liquid chromatography coupled-diode array detector

    PubMed Central

    Weon, Jin Bae; Lee, Bohyoung; Yun, Bo-Ra; Lee, Jiwoo; Ma, Choong Je

    2012-01-01

    Background: Cynanchum paniculatum Kitagawa belongs to Asclepiadaceae and was used in traditional medicine to invigorate blood, alleviate edema, relieve pain, and relieve toxicity for a long time. Objective: A novel and reliable high performance liquid chromatography coupled with diode array detector method has been established for simultaneous determination of 10 bioactive compounds isolated from Cynanchum paniculatum Kitagawa, one of the herbal medicines. Materials and Methods: The chromatography analysis was performed on a SHISEIDO C18 column (S-5 μm, 4.6 mm I.D. × 250 mm) at 35°C with a gradient elution of acetonitrile and water at a flow rate of 1ml/min and UV detection at 210, 230, and 280 nm. Results: The method was validated for linearity, precision, and accuracy. All calibration curves showed good linear regression (r2 > 0.9996). Limits of detection (LOD) and limits of quantification (LOQ) fell in the ranges 0.01 - 0.28 μg/ml and 0.04 - 0.83 μg/ml, respectively. The relative standard deviation (RSD) of the intra- and inter- day test, precision test were within 1.92% and 2.43%, respectively. The mean recovery of all ranged from 92.82 to 107.96% with RSD values 0.12 - 2.18%. Conclusion: The results of validation appeared that this established method was very accurate and stabilized for the quantification of 10 bioactive compounds isolated from C. paniculatum. PMID:23060698

  7. Determination of sulfadiazine in Jiaozhou Bay using molecularly imprinted solid-phase extraction followed by high-performance liquid chromatography with a diode-array detector.

    PubMed

    Lian, Ziru; He, Xingliang; Wang, Jiangtao

    2014-04-15

    A highly selective sample cleanup procedure featuring molecularly imprinted solid-phase extraction (MISPE) was developed for the isolation and determination of sulfadiazine (SDZ) in seawater samples from Jiaozhou Bay, China. The molecularly imprinted polymer (MIP) was prepared using SDZ as the template molecule and methacrylic acid as the functional monomer. The MIP was used as a selective sorbent for the solid-phase extraction of SDZ. An off-line MISPE method followed by high-performance liquid chromatography (HPLC) with diode-array detection was established for the analysis of SDZ. Good linearity of the MISPE column for SDZ standard solutions was obtained within 0-200μgL(-1) (R(2)>0.99). The recoveries of spiked seawater samples were satisfactory as high as 88%. Finally, seven samples in Jiaozhou Bay were determined and there was no sulfadiazine found except #2 and #5 sample. The concentrations were respectively 0.33μgL(-1) and 0.28μgL(-1), and the relative standard deviations were 1.35% and 4.13% (n=3).

  8. Determination of crystal violet in seawater and seafood samples through off-line molecularly imprinted SPE followed by HPLC with diode-array detection.

    PubMed

    Lian, Ziru; Wang, Jiangtao

    2013-03-01

    A highly selective sample cleanup procedure combined with molecularly imprinted SPE was developed for the isolation of crystal violet from seawater and seafood samples. The molecularly imprinted polymer was prepared using crystal violet as the template molecule, methacrylic acid as the functional monomer, and ethylene glycol dimethacrylate as the cross-linker. The crystal violet-imprinted polymer was used as the selective sorbent for the SPE of crystal violet. An off-line molecularly imprinted SPE method followed by HPLC with diode-array detection for the analysis of crystal violet was also established. Good linearity on the molecularly imprinted SPE columns was obtained from 0 to 200 μg/L (R(2) > 0.99). The result demonstrated that the proposed method can be used for the direct determination of crystal violet in seawater and seafood samples. Finally, five samples were analyzed and the following crystal violet concentrations were obtained: 0.92 and 0.52 μg/L in two seawater samples, as well as 0.36 and 0.27 μg/kg in two seafood samples. There is no crystal violet detected in the third seawater sample.

  9. Simultaneous determination of flavonoids, isochlorogenic acids and triterpenoids in Ilex hainanensis Using high performance liquid chromatography coupled with diode array and evaporative light scattering detection.

    PubMed

    Peng, Bo; Qiao, Chun-Feng; Zhao, Jing; Huang, Wei-Hua; Hu, De-Jun; Liu, Hua-Gang; Li, Shao-Ping

    2013-03-04

    A high performance liquid chromatography coupled with diode array and evaporative light scattering detection (HPLC-DAD-ELSD) method for simultaneous determination of eight major bioactive compounds including two flavonoids (rutin and eriodictyol-7-O-β-D-glucopyranoside), two isochlorogenic acids (isochlorogenic acid A and isochlorogenic acid C) and four triterpenoids (ilexhainanoside D, ilexsaponin A1, ilexgenin A and ursolic acid) in Ilex hainanensis has been developed for the first time. The 283 nm wavelength was chosen for determination of two flavonoids and two isochlorogenic acids. ELSD was applied to determine four triterpenoids. The analysis was performed on an Agilent Zorbax SB-C18 column (250 × 4.6 mm i.d., 5 µm) with gradient elution of 0.2% formic acid in water and acetonitrile. The method was validated for linearity, limit of detection, limit of quantification, precision, repeatability and accuracy. The proposed method has been successfully applied for simultaneous quantification of the analytes in four samples of Ilex hainanensis, which is helpful for quality control of this plant.

  10. Simultaneous analysis of six aristolochic acids and five aristolactams in herbal plants and their preparations by high-performance liquid chromatography-diode array detection-fluorescence detection.

    PubMed

    Yuan, Jinbin; Liu, Qian; Zhu, Weifeng; Ding, Li; Tang, Fei; Yao, Shouzhuo

    2008-02-22

    Aristolochic acid analogues, including aristolochic acids (AAs) and aristolactams (ALs), are known to be nephrotoxic, carcinogenic and mutagenic. In this paper, a high-performance liquid chromatography-diode array detection-fluorescence detection (HPLC-DAD-FLD) method was developed for the simultaneous determination of six AAs together with five ALs. Baseline separation was obtained on an ODS C18 analytical column with 0.2% HAc/methanol gradient elution. The hyphenation of DAD and FLD allows the method to directly meet the analysis requirements of most herbal plants with high sensitivity and selectivity. For trace analysis, aristolochic acids were reduced to their corresponding aritstolactams in acidic solution containing iron powder, and then high sensitive detection and quantification were carried out. The method was successfully validated in the matrices of various Aristolochiaceae plants and their preparations. Linearities of around 3-4 orders of magnitude were obtained with correlation coefficients exceeding 0.9970. The detection limits were decreased to 0.2ng/ml. Satisfactory intra-day and inter-day precisions were achieved with RSDs less than 5.74%, and the average recovery factors were in the range of 94.5-99.2%.

  11. Dispersive liquid-liquid microextraction for the determination of flavonoid aglycone compounds in honey using liquid chromatography with diode array detection and time-of-flight mass spectrometry.

    PubMed

    Campillo, Natalia; Viñas, Pilar; Férez-Melgarejo, Gema; Hernández-Córdoba, Manuel

    2015-01-01

    A rapid approach for the determination of eight flavonoid aglycone compounds, baicalein, hesperitin, fisetin, naringenin, chrysin, myricetin, quercetin and kaempferol, in honey samples and related products has been optimized and validated. The enriched extracts obtained by dispersive liquid-liquid microextraction (DLLME) were analyzed by liquid chromatography with diode array detection coupled to electrospray ionization and time-of-flight mass spectrometry (LC-DAD-ESI-ToFMS). For DLLME, using acetonitrile and chloroform as disperser and extractant solvents, respectively, a Taguchi experimental method was applied to find the optimal combination of following six factors: disperser and extractant solvent volumes, sodium chloride concentration, pH of the aqueous phase, honey mass and centrifugation time. The sedimented organic phase obtained after centrifugation was evaporated, reconstituted in acetonitrile and submitted to LC. The matrix effect was evaluated, and it was concluded that sample quantification can be carried out against aqueous external standards when using DAD and by matrix-matched calibration in the case of ToFMS. Detection limits in the ranges of 0.4-4 and 0.01-0.5 ng g(-1) were obtained for DAD and ToFMS, respectively. Satisfactory recovery values between 80 and 111% were obtained for three spiked samples. Honeys and related products were analyzed and flavonoids were found within a wide range.

  12. Analytical method development for the determination of emerging contaminants in water using supercritical-fluid chromatography coupled with diode-array detection.

    PubMed

    Del Carmen Salvatierra-Stamp, Vilma; Ceballos-Magaña, Silvia G; Gonzalez, Jorge; Ibarra-Galván, Valentin; Muñiz-Valencia, Roberto

    2015-05-01

    An analytical method using supercritical-fluid chromatography coupled with diode-array detection for the determination of seven emerging contaminants-two pharmaceuticals (carbamazepine and glyburide), three endocrine disruptors (17α-ethinyl estradiol, bisphenol A, and 17β-estradiol), one bactericide (triclosan), and one pesticide (diuron)-was developed and validated. These contaminants were chosen because of their frequency of use and their toxic effects on both humans and the environment. The optimized chromatographic separation on a Viridis BEH 2-EP column achieved baseline resolution for all compounds in less than 10 min. This separation was applied to environmental water samples after sample preparation. The optimized sample treatment involved a preconcentration step by means of solid-phase extraction using C18-OH cartridges. The proposed method was validated, finding recoveries higher than 94 % and limits of detection and limits of quantification in the range of 0.10-1.59 μg L(-1) and 0.31-4.83 μg L(-1), respectively. Method validation established the proposed method to be selective, linear, accurate, and precise. Finally, the method was successfully applied to environmental water samples.

  13. Efficiency droop enhancement in AlGaN deep ultraviolet light-emitting diodes by making whole barriers but the bottom Mg doped

    NASA Astrophysics Data System (ADS)

    Sun, Jie; Sun, Huiqing; Yi, Xinyan; Yang, Xian; Fan, Xuancong; Zhang, Cheng; Zhang, Zhuding; Guo, Zhiyou

    2016-09-01

    Ultra violet light-emitting diodes (UVLEDs) with different types of Mg-doped barriers have been studied. The energy band diagrams, internal quantum efficiency, total output power and radiative recombination rate are investigated by APSYS software. The simulation results show that the UVLED with only a p-doped top barrier get little enhancement comparing to the conventional one, on the contrary the structure with p-doping in all but the bottom barriers has a much better optical and electrical properties due to enhancement of the holes' injection and the electrons' confinement. The efficiency droop is significantly alleviated and the light output power is greatly enhanced. To avoid forming a PN junction by the bottom barrier and the n-AlGaN in the proposed structure, therefore, the bottom barrier isn't p-doped. Then structures with different hole densities in the Mg-doped barriers have been studied numerically and that confirmed the best.

  14. Mechanics of cadmium telluride-zinc telluride nucleation on (112) Si for mercury cadmium telluride infrared photo-diode arrays

    NASA Astrophysics Data System (ADS)

    Dhar, Nibir Kumar

    Epitaxy of CdTe/ZnTe on the extremely large lattice mismatched Si leads to high density of dislocations, multi-domain facets, rough surface morphology, and often Cd-terminated surface polarity. These problems, related to the mode of nucleation and growth, limit its application to manufacture improved HgCdTe based large area infrared focal plane arrays. Thermo-kinetics of ZnTe nucleation on "atomically" clean, and arsenic modified nominal and vicinal (112) Si surfaces were investigated in a molecular beam epitaxy system. Transition state theory was invoked to understand and model ZnTe nucleation processes. Thin ZnTe templates were fabricated by: (1) migration enhanced epitaxy (MEE), and (2) crystallized amorphous deposits for relaxed epitaxy (CADRE) procedure developed in this research. MBE CdTe/ZnTe/Si structures were characterized, and used to make improved HgCdTe detector arrays. MEE ZnTe nucleation produced small, but misoriented islands. Nucleation involved dissociative adsorption of Tesb2 into highly immobile chemisorbed atoms, with Si-Te covalent bond energy of 3.46 ± 0.1 eV. CdTe layers were heavily twinned, with high dislocation densities, and crystallographic facets; surface morphologies were rough, and exhibited temperature dependent polarity transformation. The CADRE process led to polycrystalline CdTe/ZnTe structures. MEE ZnTe growth on As-terminated Si surfaces was initially by Stranski-Krastanaw mode via chemisorption of tellurium atoms which produced (2sqrt{3} x 2sqrt{3})R30 reconstructed surfaces. The CADRE process did not involve island nucleation. CdTe layers deposited on ZnTe templates prepared by MEE and CADRE were Te-terminated, with extremely good morphologies. For nominal Si, twin concentrations were two orders of magnitude lower than in equivalent structures grown on "atomically" clean Si surfaces. Twin free CdTe layers with dislocation densities in the range of 1-5 × 10sp5 cmsp{-2} were obtained by the CADRE technique. A model is proposed

  15. Degradation of the Adhesive Properties of MD-944 Diode Tape by Simulated Low Earth Orbit Environmental Factors

    NASA Technical Reports Server (NTRS)

    Albyn, K.; Finckenor, M.

    2006-01-01

    The International Space Station (ISS) solar arrays utilize MD-944 diode tape with silicone pressure-sensitive adhesive to protect the underlying diodes and also provide a high-emittance surface. On-orbit, the silicone adhesive will be exposed and ultimately convert to a glass-like silicate due to atomic oxygen (AO). The current operational plan is to retract ISS solar array P6 and leave it stored under load for a long duration (6 mo or more). The exposed silicone adhesive must not cause the solar array to stick to itself or cause the solar array to fail during redeployment. The Environmental Effects Branch at Marshall Space Flight Center, under direction from the ISS Program Office Environments Team, performed simulated space environment exposures with 5-eV AO, near ultraviolet radiation and ionizing radiation. The exposed diode tape samples were put under preload and then the resulting blocking force was measured using a tensile test machine. Test results indicate that high-energy AO, ultraviolet radiation, and electron ionizing radiation exposure all reduce the blocking force for a silicone-to-silicone bond. AO exposure produces the most significant reduction in blocking force

  16. 25 W of average power at 172 nm in the vacuum ultraviolet from flat, efficient lamps driven by interlaced arrays of microcavity plasmas

    NASA Astrophysics Data System (ADS)

    Park, S.-J.; Herring, C. M.; Mironov, A. E.; Cho, J. H.; Eden, J. G.

    2017-04-01

    More than 25 W of average power and >800 W of peak power have been generated at λ =172 nm (h ν =7.2 eV) in the vacuum ultraviolet (VUV) from the Xe2 molecule in flat, 10 × 10 cm2 lamps having an active area and volume of 80 cm2 and <60 cm3, respectively. Powered by at least two interlaced arrays of microplasmas generated within cavities fabricated into an interior surface of the <6 mm thick lamp, these lamps have an electrical-to-optical conversion efficiency >20 % . For a bipolar voltage waveform driving frequency of 137 kHz and a 54% Xe/Ne gas fill mixture at a 300 K pressure of 550 Torr, the lamp generates as much as 31.5 W of average power and intensities >350 mW cm-2 in 40-60 μJ, 70±10 ns FWHM pulses produced in a burst mode-four pulses of 600-850 W peak power in every cycle of the driving waveform. The lamp intensity is uniform to within ±2.5% at ≥10 mm from its surface and average power varies linearly with pulse repetition frequency throughout the 18-135 kHz interval. The spectral breadth of the Xe dimer emission is ˜9 nm FWHM and time-resolved, spatial intensity maps show improved utilization of the power pulse (VṡI) with two or more microcavity arrays that are interleaved. This photonic source technology is capable of generating unprecedented power levels in the VUV spectral region (e.g., ˜2.5 kW m-2) with tiled lamps.

  17. Simple locking of infrared and ultraviolet diode lasers to a visible laser using a LabVIEW proportional-integral-derivative controller on a Fabry-Perot signal.

    PubMed

    Kwolek, J M; Wells, J E; Goodman, D S; Smith, W W

    2016-05-01

    Simultaneous laser locking of infrared (IR) and ultraviolet lasers to a visible stabilized reference laser is demonstrated via a Fabry-Perot (FP) cavity. LabVIEW is used to analyze the input, and an internal proportional-integral-derivative algorithm converts the FP signal to an analog locking feedback signal. The locking program stabilized both lasers to a long term stability of better than 9 MHz, with a custom-built IR laser undergoing significant improvement in frequency stabilization. The results of this study demonstrate the viability of a simple, computer-controlled, non-temperature-stabilized FP locking scheme for our applications, laser cooling of Ca(+) ions, and its use in other applications with similar modest frequency stabilization requirements.

  18. Simple locking of infrared and ultraviolet diode lasers to a visible laser using a LabVIEW proportional-integral-derivative controller on a Fabry-Perot signal

    NASA Astrophysics Data System (ADS)

    Kwolek, J. M.; Wells, J. E.; Goodman, D. S.; Smith, W. W.

    2016-05-01

    Simultaneous laser locking of infrared (IR) and ultraviolet lasers to a visible stabilized reference laser is demonstrated via a Fabry-Perot (FP) cavity. LabVIEW is used to analyze the input, and an internal proportional-integral-derivative algorithm converts the FP signal to an analog locking feedback signal. The locking program stabilized both lasers to a long term stability of better than 9 MHz, with a custom-built IR laser undergoing significant improvement in frequency stabilization. The results of this study demonstrate the viability of a simple, computer-controlled, non-temperature-stabilized FP locking scheme for our applications, laser cooling of Ca+ ions, and its use in other applications with similar modest frequency stabilization requirements.

  19. Ultraviolet light stable and transparent sol-gel methyl siloxane hybrid material for UV light-emitting diode (UV LED) encapsulant.

    PubMed

    Bae, Jun-Young; Kim, YongHo; Kim, HweaYoon; Kim, YuBae; Jin, Jungho; Bae, Byeong-Soo

    2015-01-21

    An ultraviolet (UV) transparent and stable methyl-siloxane hybrid material was prepared by a facile sol-gel method. The transparency and stability of a UV-LED encapsulant is an important issue because it affects UV light extraction efficiency and long-term reliability. We introduced a novel concept for UV-LED encapsulation using a thermally curable oligosiloxane resin. The encapsulant was fabricated by a hydrosilylation of hydrogen-methyl oligosiloxane resin and vinyl-methyl siloxane resin, and showed a comparable transmittance to polydimethylsiloxane (PDMS) in the UVB (∼300 nm) region. Most remarkably, the methyl-siloxane hybrid materials exhibited long-term UV stability under light soaking in UVB (∼300 nm) for 1000 h.

  20. Development of highly durable deep-ultraviolet AlGaN-based LED multichip array with hemispherical encapsulated structures using a selected resin through a detailed feasibility study

    NASA Astrophysics Data System (ADS)

    Nagai, Shoko; Yamada, Kiho; Hirano, Akira; Ippommatsu, Masamichi; Ito, Masahiro; Morishima, Naoki; Aosaki, Ko; Honda, Yoshio; Amano, Hiroshi; Akasaki, Isamu

    2016-08-01

    To replace mercury lamps with AlGaN-based deep-ultraviolet (DUV) LEDs, a simple and low-cost package with increased light extraction efficiency (LEE) is indispensable. Therefore, resin encapsulation is considered to be a key technology. However, the photochemical reactions induced by DUV light cause serious problems, and conventional resins cannot be used. In the former part of this study, a comparison of a silicone resin and fluorine polymers was carried out in terms of their suitability for encapsulation, and we concluded that only one of the fluorine polymers can be used for encapsulation. In the latter part, the endurance of encapsulation using the selected fluorine polymer was investigated, and we confirmed that the selected fluorine polymer can guarantee a lifetime of over 6,000 h at a wavelength of 265 nm. Furthermore, a 3 × 4 array module of encapsulated dies on a simple AlN submount was fabricated, demonstrating the possibility of W/cm2-class lighting.

  1. ZnO nanorod arrays and direct wire bonding on GaN surfaces for rapid fabrication of antireflective, high-temperature ultraviolet sensors

    NASA Astrophysics Data System (ADS)

    So, Hongyun; Senesky, Debbie G.

    2016-11-01

    Rapid, cost-effective, and simple fabrication/packaging of microscale gallium nitride (GaN) ultraviolet (UV) sensors are demonstrated using zinc oxide nanorod arrays (ZnO NRAs) as an antireflective layer and direct bonding of aluminum wires to the GaN surface. The presence of the ZnO NRAs on the GaN surface significantly reduced the reflectance to less than 1% in the UV and 4% in the visible light region. As a result, the devices fabricated with ZnO NRAs and mechanically stable aluminum bonding wires (pull strength of 3-5 gf) showed higher sensitivity (136.3% at room temperature and 148.2% increase at 250 °C) when compared with devices with bare (uncoated) GaN surfaces. In addition, the devices demonstrated reliable operation at high temperatures up to 300 °C, supporting the feasibility of simple and cost-effective UV sensors operating with higher sensitivity in high-temperature conditions, such as in combustion, downhole, and space exploration applications.

  2. An elegant route to overcome fundamentally-limited light extraction in AlGaN deep-ultraviolet light-emitting diodes: Preferential outcoupling of strong in-plane emission

    PubMed Central

    Lee, Jong Won; Kim, Dong Yeong; Park, Jun Hyuk; Schubert, E. Fred; Kim, Jungsub; Lee, Jinsub; Kim, Yong-Il; Park, Youngsoo; Kim, Jong Kyu

    2016-01-01

    While there is an urgent need for semiconductor-based efficient deep ultraviolet (DUV) sources, the efficiency of AlGaN DUV light-emitting diodes (LEDs) remains very low because the extraction of DUV photons is significantly limited by intrinsic material properties of AlGaN. Here, we present an elegant approach based on a DUV LED having multiple mesa stripes whose inclined sidewalls are covered by a MgF2/Al omni-directional mirror to take advantage of the strongly anisotropic transverse-magnetic polarized emission pattern of AlGaN quantum wells. The sidewall-emission-enhanced DUV LED breaks through the fundamental limitations caused by the intrinsic properties of AlGaN, thus shows a remarkable improvement in light extraction as well as operating voltage. Furthermore, an analytic model is developed to understand and precisely estimate the extraction of DUV photons from AlGaN DUV LEDs, and hence to provide promising routes for maximizing the power conversion efficiency. PMID:26935402

  3. An elegant route to overcome fundamentally-limited light extraction in AlGaN deep-ultraviolet light-emitting diodes: Preferential outcoupling of strong in-plane emission.

    PubMed

    Lee, Jong Won; Kim, Dong Yeong; Park, Jun Hyuk; Schubert, E Fred; Kim, Jungsub; Lee, Jinsub; Kim, Yong-Il; Park, Youngsoo; Kim, Jong Kyu

    2016-03-03

    While there is an urgent need for semiconductor-based efficient deep ultraviolet (DUV) sources, the efficiency of AlGaN DUV light-emitting diodes (LEDs) remains very low because the extraction of DUV photons is significantly limited by intrinsic material properties of AlGaN. Here, we present an elegant approach based on a DUV LED having multiple mesa stripes whose inclined sidewalls are covered by a MgF2/Al omni-directional mirror to take advantage of the strongly anisotropic transverse-magnetic polarized emission pattern of AlGaN quantum wells. The sidewall-emission-enhanced DUV LED breaks through the fundamental limitations caused by the intrinsic properties of AlGaN, thus shows a remarkable improvement in light extraction as well as operating voltage. Furthermore, an analytic model is developed to understand and precisely estimate the extraction of DUV photons from AlGaN DUV LEDs, and hence to provide promising routes for maximizing the power conversion efficiency.

  4. Qualitative and quantitative analysis of anthraquinones in rhubarbs by high performance liquid chromatography with diode array detector and mass spectrometry.

    PubMed

    Wei, Shao-yin; Yao, Wen-xin; Ji, Wen-yuan; Wei, Jia-qi; Peng, Shi-qi

    2013-12-01

    Rhubarb is well known in traditional Chinese medicines (TCMs) mainly due to its effective purgative activity. Anthraquinones, including anthraquinone derivatives and their glycosides, are thought to be the major active components in rhubarb. To improve the quality control method of rhubarb, we studied on the extraction method, and did qualitative and quantitative analysis of widely used rhubarbs, Rheum tanguticum Maxim. ex Balf. and Rheum palmatum L., by HPLC-photodiode array detection (HPLC-DAD) and HPLC-mass spectrum (HPLC-MS) on a Waters SymmetryShield RP18 column (250 mm × 4.6 mm i.d., 5 μm). Amount of five anthraquinones was viewed as the evaluating standard. A standardized characteristic fingerprint of rhubarb was provided. From the quantitative analysis, the rationality was demonstrated for ancestors to use these two species of rhubarb equally. Under modern extraction methods, the amount of five anthraquinones in Rheum tanguticum Maxim. ex Balf. is higher than that in Rheum palmatum L. Among various extraction methods, ultrasonication with 70% methanol for 30 min is a promising one. For HPLC analysis, mobile phase consisted of methanol and 0.1% phosphoric acid in water with a gradient program, the detection wavelength at 280nm for fingerprinting analysis and 254 nm for quantitative analysis are good choices.

  5. Diode-pumped continuous-wave and femtosecond Cr:LiCAF lasers with high average power in the near infrared, visible and near ultraviolet.

    PubMed

    Demirbas, Umit; Baali, Ilyes; Acar, Durmus Alp Emre; Leitenstorfer, Alfred

    2015-04-06

    We demonstrate continuous-wave (cw), cw frequency-doubled, cw mode-locked and Q-switched mode-locked operation of multimode diode-pumped Cr:LiCAF lasers with record average powers. Up to 2.54 W of cw output is obtained around 805 nm at an absorbed pump power of 5.5 W. Using intracavity frequency doubling with a BBO crystal, 0.9 W are generated around 402 nm, corresponding to an optical-to-optical conversion efficiency of 12%. With an intracavity birefringent tuning plate, the fundamental and frequency-doubled laser output is tuned continuously in a broad wavelength range from 745 nm to 885 nm and from 375 to 440 nm, respectively. A saturable Bragg reflector is used to initiate and sustain mode locking. In the cw mode-locked regime, the Cr:LiCAF laser produces 105-fs long pulses near 810 nm with an average power of 0.75 W. The repetition rate is 96.4 MHz, resulting in pulse energies of 7.7 nJ and peak powers of 65 kW. In Q-switched mode-locked operation, pulses with energies above 150 nJ are generated.

  6. Ultraviolet C upconversion fluorescence of trivalent erbium in BaGd2ZnO5 phosphor excited by a visible commercial light-emitting diode.

    PubMed

    Yang, Yanmin; Mi, Chao; Su, Xianyuan; Jiao, Fuyun; Liu, Linlin; Zhang, Jiao; Yu, Fang; Li, Xiaodong; Liu, Yanzhou; Mai, Yaohua

    2014-04-01

    Multiple ultraviolet (UV) emission bands have been obtained in Er3+ doped BaGd2ZnO5 phosphor under the excitation of a 532 nm solid-state laser, and the emission peaks at 217, 254, 278, 296, 314, 348, 374 and 394 nm were determined to stem from the high-energy states 4D(1/2), 4D(7/2), 2H(9/2), 2P(1/2), 2P(3/2), 4G(7/2), 4G(11/2), 4H(9/2) of trivalent erbium, respectively. Some UV emission bands in the UVC region can be observed when the sample was excited by commercial green (529 nm) and blue (460 nm) LED. In view of the small size, low-drive voltage and price of LED, UVC upconversion phosphor BaGd2ZnO5:Er3+ excited by visible LED has potential application in environmental sciences.

  7. Diagnosing x-ray power and energy of tungsten wire array z-pinch with a flat spectral response x-ray diode

    SciTech Connect

    Wang, Kun-lun; Ren, Xiao-dong; Huang, Xian-bin Zhang, Si-qun; Zhou, Shao-tong; Dan, Jia-kun; Li, Jing; Xu, Qiang; Ouyang, Kai; Cai, Hong-chun; Wei, Bing; Ji, Ce; Feng, Shu-ping; Wang, Meng; Xie, Wei-ping; Deng, Jian-jun

    2015-11-15

    Fast z-pinch is a very efficient way of converting electromagnetic energy to radiation. With an 8-10 MA current on primary test stand facility, about 1 MJ electromagnetic energy is delivered to vacuum chamber, which heats z-pinch plasma to radiate soft x-ray. To develop a pulsed high power x-ray source, we studied the applicability of diagnosing x-ray power from tungsten wire array z-pinch with a flat spectral response x-ray diode (FSR-XRD). The detector was originally developed to diagnose radiation of a hohlraum in SG-III prototype laser facility. It utilized a gold cathode XRD and a specially configured compound gold filter to yield a nearly flat spectral response in photon energy range of 0.1-4 keV. In practice, it was critical to avoid surface contamination of gold cathode. It is illustrated that an exposure of an XRD to multiple shots caused a significant change of response. Thus, in diagnosing x-ray power and energy, we used each XRD in only one shot after calibration. In a shot serial, output of FSR-XRD was compared with output of a nickel bolometer. In these shots, the outputs agreed with each other within their uncertainties which were about 12% for FSR-XRD and about 15% for bolometer. Moreover, the ratios between the FSR-XRD and the bolometer among different shots were explored. In 8 shots, the standard deviation of the ratio was 6%. It is comparable to XRD response change of 7%.

  8. Determination of Polycyclic Aromatic Hydrocarbons in Commercial Parenteral Formulations and Medications Using High-Performance Liquid Chromatography with Diode Array Detection.

    PubMed

    Barichello, Marcia M; Bohrer, Denise; Viana, Carine; Carvalho, Leandro M; Nascimento, Paulo C

    2017-02-22

    HPLC coupled to UV diode array detection (DAD) is proposed for the determination of polycyclic aromatic hydrocarbons (PAHs) in pharmaceutical products for parenteral administration. Because rubber is a possible source of PAHs for these products, samples stored in containers with rubber parts were selected for the analysis. The basis for method optimization was EPA Method 8310, which determines 16 priority PAHs in ground water and wastewater by HPLC using both UV and fluorescence detection. Using DAD, two channels were selected for detection, with one operating at 254 nm for the detection of nine PAHs and the other at 225 nm for the detection of seven PAHs. This method allowed for the detection of PAHs using external calibration with LODs and LOQs ranging from 0.001 to 0.060 μg/mL and from 0.003 to 0.167 μg/mL, respectively. Within-day precision, expressed as RSD, varied from 1.24 to 7.76% for PAH concentrations from 0.05 to 0.50 μg/mL, and intraday precision varied from 3.10 to 9.40% for the same concentration range. Method accuracy was confirmed by recoveries of 75–120% of the spiked samples. This method was applied for the determination of PAHs in three commercial infusion solutions and in nine different medications stored in syringes prior to administration to patients. Twelve of 16 PAHs were found in these samples. Total PAH concentrations varied from 0.13 to 13.50 μg/mL. Pyrene was the most prevalent contaminant, being present in 11 of 12 samples in concentrations ranging from 0.17 to 4.80 μg/mL. This method presented good sensitivity for the measurement of PAH in the target samples, allowing for the determination of the 16 priority PAHs in one run and in 30 min.

  9. Automated determination of phenylcarbamate herbicides in environmental waters by on-line trace enrichment and reversed-phase liquid chromatography-diode array detection.

    PubMed

    Hidalgo, C; Sancho, J V; López, F J; Hernández, F

    1998-10-09

    A fully automated liquid chromatographic method using on-line trace-enrichment, gradient elution and diode array detection is described for the trace-level determination of several phenylcarbamate herbicides, such as carbetamide, propham, desmedipham, phenmedipham, chlorbufam and chlorpropham, in environmental water samples. In this work, two different enrichment pre-columns have been assayed, a 5.8 x 4.6 mm I.D., 10 microns ODS Prelute cartridge and a 10 x 2 mm I.D. cartridge filled with 10 microns PRP-1 polymer, both coupled to a 150 x 4.6 mm I.D. analytical column filled with 5 microns ODS. Using the C18 pre-column, up to 50 ml of water sample could be percolated without peak broadening of any compound. However, a lack of reproducibility was observed in the case of carbetamide, the most polar analyte, after performing recovery experiments by percolating drinking and surface water samples spiked at several levels (0.5 and 4 micrograms l-1). On the other hand, the PRP-1 pre-column allowed the enrichment up to 100 ml of water sample with satisfactory results for every compound, including carbetamide. The procedure was validated by recovery experiments in environmental water samples spiked at 0.2 and 1 microgram l-1 yielding average recoveries between 84-108% with relative standard deviations in the range 2-12%. Detection limits as low as 0.04 microgram l-1 were achieved. It was observed that desmedipham and phenmedipham degraded rapidly in the environmental water samples as showed the degradation studies performed along 24 h in drinking and surface waters spiked at 4 micrograms l-1. Although the standard mixture, prepared in HPLC water, was stable for around one week, in the environmental water matrices more than 95% of each herbicide degraded after 6 h, and new chromatographic peaks corresponding to the degradation products were detected.

  10. Intelligent peak deconvolution through in-depth study of the data matrix from liquid chromatography coupled with a photo-diode array detector applied to pharmaceutical analysis.

    PubMed

    Arase, Shuntaro; Horie, Kanta; Kato, Takashi; Noda, Akira; Mito, Yasuhiro; Takahashi, Masatoshi; Yanagisawa, Toshinobu

    2016-10-21

    Multivariate curve resolution-alternating least squares (MCR-ALS) method was investigated for its potential to accelerate pharmaceutical research and development. The fast and efficient separation of complex mixtures consisting of multiple components, including impurities as well as major drug substances, remains a challenging application for liquid chromatography in the field of pharmaceutical analysis. In this paper we suggest an integrated analysis algorithm functioning on a matrix of data generated from HPLC coupled with photo-diode array detector (HPLC-PDA) and consisting of the mathematical program for the developed multivariate curve resolution method using an expectation maximization (EM) algorithm with a bidirectional exponentially modified Gaussian (BEMG) model function as a constraint for chromatograms and numerous PDA spectra aligned with time axis. The algorithm provided less than ±1.0% error between true and separated peak area values at resolution (Rs) of 0.6 using simulation data for a three-component mixture with an elution order of a/b/c with similarity (a/b)=0.8410, (b/c)=0.9123 and (a/c)=0.9809 of spectra at peak apex. This software concept provides fast and robust separation analysis even when method development efforts fail to achieve complete separation of the target peaks. Additionally, this approach is potentially applicable to peak deconvolution, allowing quantitative analysis of co-eluted compounds having exactly the same molecular weight. This is complementary to the use of LC-MS to perform quantitative analysis on co-eluted compounds using selected ions to differentiate the proportion of response attributable to each compound.

  11. Development and validation of an high-performance liquid chromatography-diode array detector method for the simultaneous determination of six phenolic compounds in abnormal savda munziq decoction

    PubMed Central

    Tian, Shuge; Liu, Wenxian; Liu, Feng; Zhang, Xuejia; Upur, Halmuart

    2015-01-01

    Aims: Given the high-effectiveness and low-toxicity of abnormal savda munziq (ASMQ), its herbal formulation has long been used in traditional Uyghur medicine to treat complex diseases, such as cancer, diabetes, and cardiovascular diseases. Settings and Design: ASMQ decoction by reversed-phase high-performance liquid chromatography coupled with a diode array detector was successfully developed for the simultaneous quality assessment of gallic acid, protocatechuic acid, caffeic acid, rutin, rosmarinic acid, and luteolin. The six phenolic compounds were separated on an Agilent TC-C18 reversed-phase analytical column (4.6 × 250 mm, 5 μm) by gradient elution using 0.3% aqueous formic acid (v/v) and 0.3% methanol formic acid (v/v) at 1.0 mL/min. Materials and Methods: The plant material was separately ground and mixed at the following ratios (10): Cordia dichotoma (10.6), Anchusa italic (10.6), Euphorbia humifusa (4.9), Adiantum capillus-veneris (4.9), Ziziphus jujube (4.9), Glycyrrhiza uralensis (7.1), Foeniculum vulgare (4.9), Lavandula angustifolia (4.9), Dracocephalum moldavica L. (4.9), and Alhagi pseudoalhagi (42.3). Statistical Analysis Used: The precisions of all six compounds were <0.60%, and the average recoveries ranged from 99.39% to 104.85%. Highly significant linear correlations were found between component concentrations and specific chromatographic peak areas (R2 > 0.999). Results: The proposed method was successfully applied to determine the levels of six active components in ASMQ. Conclusions: Given the simplicity, precision, specificity, and sensitivity of the method, it can be utilized as a quality control approach to simultaneously determining the six phenolic compounds in AMSQ. PMID:25709227

  12. Determination of chlorophylls in Taraxacum formosanum by high-performance liquid chromatography-diode array detection-mass spectrometry and preparation by column chromatography.

    PubMed

    Loh, Chin Hoe; Inbaraj, Baskaran Stephen; Liu, Man Hai; Chen, Bing Huei

    2012-06-20

    Taraxacum formosanum, a well-known Chinese herb shown to be protective against hepatic cancer as well as liver and lung damage, may be attributed to the presence of abundant carotenoids and chlorophylls. However, the variety and content of chlorophylls remain uncertain. The objectives of this study were to develop an high-performance liquid chromatography-diode array detection-mass spectrometry method for determination of chlorophylls in T. formosanum and preparation by column chromatography. An HyPURITY C18 column and a gradient mobile phase of water (A), methanol (B), acetonitrile (C), and acetone (D) could resolve 10 chlorophylls and an internal standard Fast Green FCF within 30 min with a flow rate at 1 mL/min and detection at 660 nm. Both chlorophylls a and a' were present in the largest amount (1389.6 μg/g), followed by chlorophylls b and b' (561.2 μg/g), pheophytins a and a' (31.7 μg/g), hydroxychlorophyll b (26.5 μg/g), hydroxychlorophylls a and a' (9.8 μg/g), and chlorophyllides a and a' (0.35 μg/g). A glass column containing 52 g of magnesium oxide-diatomaceous earth (1:3, w/w) could elute chlorophylls with 800 mL of acetone containing 50% ethanol at a flow rate of 10 mL/min. Some new chlorophyll derivatives including chlorophyllide b, pyropheophorbide b, hydroxypheophytin a, and hydroxypheophytin a' were generated during column chromatography but accompanied by a 63% loss in total chlorophylls. Thus, the possibility of chlorophyll fraction prepared from T. formosanum as a raw material for future production of functional food needs further investigation.

  13. Diagnosing x-ray power and energy of tungsten wire array z-pinch with a flat spectral response x-ray diode.

    PubMed

    Wang, Kun-lun; Ren, Xiao-dong; Huang, Xian-bin; Zhang, Si-qun; Zhou, Shao-tong; Dan, Jia-kun; Li, Jing; Xu, Qiang; Ouyang, Kai; Cai, Hong-chun; Wei, Bing; Ji, Ce; Feng, Shu-ping; Wang, Meng; Xie, Wei-ping; Deng, Jian-jun

    2015-11-01

    Fast z-pinch is a very efficient way of converting electromagnetic energy to radiation. With an 8-10 MA current on primary test stand facility, about 1 MJ electromagnetic energy is delivered to vacuum chamber, which heats z-pinch plasma to radiate soft x-ray. To develop a pulsed high power x-ray source, we studied the applicability of diagnosing x-ray power from tungsten wire array z-pinch with a flat spectral response x-ray diode (FSR-XRD). The detector was originally developed to diagnose radiation of a hohlraum in SG-III prototype laser facility. It utilized a gold cathode XRD and a specially configured compound gold filter to yield a nearly flat spectral response in photon energy range of 0.1-4 keV. In practice, it was critical to avoid surface contamination of gold cathode. It is illustrated that an exposure of an XRD to multiple shots caused a significant change of response. Thus, in diagnosing x-ray power and energy, we used each XRD in only one shot after calibration. In a shot serial, output of FSR-XRD was compared with output of a nickel bolometer. In these shots, the outputs agreed with each other within their uncertainties which were about 12% for FSR-XRD and about 15% for bolometer. Moreover, the ratios between the FSR-XRD and the bolometer among different shots were explored. In 8 shots, the standard deviation of the ratio was 6%. It is comparable to XRD response change of 7%.

  14. Antimicrobial activity of Marcetia DC species (Melastomataceae) and analysis of its flavonoids by reverse phase-high performance liquid chromatography coupled-diode array detector

    PubMed Central

    Leite, Tonny Cley Campos; de Sena, Amanda Reges; dos Santos Silva, Tânia Regina; dos Santos, Andrea Karla Almeida; Uetanabaro, Ana Paula Trovatti; Branco, Alexsandro

    2012-01-01

    Background: Marcetia genera currently comprises 29 species, with approximately 90% inhabiting Bahia (Brazil), and most are endemic to the highlands of the Chapada Diamantina (Bahia). Among the species, only M. taxifolia (A.St.-Hil.) DC. populates Brazil (state of Roraima to Paraná) and also Venezuela, Colombia, and Guyana. Objective: This work evaluated the antimicrobial activity of hexane, ethyl acetate, and methanol extracts of three species of Marcetia (Marcetia canescens Naud., M. macrophylla Wurdack, and M. taxifolia A.StHil) against several microorganism. In addition, the flavonoids were analyzed in extracts by HPLC-DAD. Materials and methods: The tests were made using Gram-positive (three strains of Staphylococcus aureus) and Gram-negative (two strains of Escherichia coli, a strain of Pseudomonas aeruginosa and another of Salmonella choleraesius) bacteria resistant and nonresistant to antibiotics and yeasts (two strains of Candida albicans and one of C. parapsilosis) by the disk diffusion method. Solid-phase extraction (SPE) was performed on the above extracts to isolate flavonoids, which were subsequently analyzed by high performance liquid chromatography coupled diode array detector (HPLC-DAD). Results: Results showed that extracts inhibited the Gram-positive bacteria and yeast. The hexane extracts possessed the lowest activity, while the ethyl acetate and methanolic extracts were more active. Conclusion: Marcetia taxifolia was more effective (active against 10 microorganisms studied), and only its methanol extract inhibited Gram-negative bacteria (P. aeruginosa and S. choleraesius). SPE and HPLC-DAD analysis showed that M. canescens and M. macrophylla contain glycosylated flavonoids, while the majority of extracts from M. taxifolia were aglycone flavonoids. PMID:23060695

  15. Determination of caffeine as a tracer of sewage effluent in natural waters by on-line solid-phase extraction and liquid chromatography with diode-array detection.

    PubMed

    Chen, Zuliang; Pavelic, Paul; Dillon, Peter; Naidu, Ravenda

    2002-11-01

    A new liquid chromatographic (LC) method with automated on-line solid phase extraction was developed to determine caffeine at sub-microgram per litre concentrations in waters. The filtered sample was pre-concentrated in a pre-column, which was backwashed with acidic water at pH of 2.70. The concentrated caffeine was separated using a C18 column with a gradient of water-acetonitrile and detected by diode array detection (DAD) at 210 nm. Four different pre-columns: C18, PRP-1, PLRP-s and Env were evaluated for the on-line solid phase extraction of caffeine. The PLRP-s pre-column allowed the enrichment of up to 100 mL of environmental water sample with highest recovery. The procedure was validated by recovery experiments in water spiked at 0.5 1.0 and 4.0 microg/L. Average recoveries were between 92.1 +/- 5.2% and 97.8 +/- 2.6%. Detection limits as low as 0.1 microg/L from 50 ml of sample were achieved. The proposed method has the advantages of higher reliability and sensitivity, simpler sample preparation and shorter analysis time in comparison with off-line solid-phase extraction. The utility of the method was demonstrated at two field sites: Bolivar and Halls Head (Australia). At Bolivar, the treatment process included 6-week lagoon storage which is believed to have attenuated caffeine, and thus limited its use as an environmental tracer of reclaimed water. At the Halls Head site, where the storage period is shorter, caffeine was detected in both the treated sewage effluent and in groundwater near ponds where the reclaimed water is at similar concentrations. These results suggest that the environmental conditions under which caffeine is conservative require better definition.

  16. Improvement of III-nitride visible and ultraviolet light-emitting diode performance, including extraction efficiency, electrical efficiency, thermal management and efficiency maintenance at high current densities

    NASA Astrophysics Data System (ADS)

    Vampola, Kenneth

    In this work, highly efficient broad-area LEDs on bulk GaN substrates were developed and the fabrication process and device layout were optimized. This optimization relied in part on electrical, optical, thermal and recombination models. The peak external quantum efficiency of the 450 nm LEDs was over 68% when biased at 20 mA. The efficiency characteristic showed a typical droop curve, decreasing at high current densities. The cause of this droop is unknown. An exploratory experiment was conducted to characterize electron overflow and its role in efficiency droop. Novel device structures were developed, allowing direct measurement of overflow electrons in LED-like structures under electrical injection. In these test structures, electrons were observed in the p-type region of the LED only at current densities where efficiency droop was active. The onset of efficiency droop was preceded by the onset of electron overflow. However, the magnitude of the overflow current could not be measured and it is undetermined whether the dominant cause of efficiency droop is electron overflow or some other process such as Auger recombination. Calibration structures allowing measurement of the magnitude of the overflow are proposed. Work on deep-ultraviolet, 275 nm, LEDs is also presented. Demonstration of direct-wafer bonded LEDs to beta-Ga2O3 is presented. A SiC substrate removal process is discussed. LEDs fabricated by this flip-chip process exhibited up to 1.8 times greater power compared to LEDs fabricated by a standard process but suffered from increased forward voltage and premature failure. Further process development leading to electrically efficient operation is proposed.

  17. Development of nitrogen-enriched carbonaceous material coated titania nanotubes array as a fiber coating for solid-phase microextraction of ultraviolet filters in environmental water.

    PubMed

    Ma, Mingguang; Wang, Huiju; Zhen, Qi; Zhang, Min; Du, Xinzhen

    2017-05-15

    A novel solid-phase microextraction (SPME) fiber was fabricated by direct electrodeposition of polyaniline (PANI) coated the titania nanotube arrays in situ grown on the titanium wire followed by carbonization at 500°C under nitrogen atmosphere. The resulting titanium-based fiber with nitrogen-enriched carbonaceous material coated titania nanotubes (N-C/TiO2NTs/Ti) showed better extraction performance for ultraviolet (UV) filters among model aromatic compounds compared with common PANI as well as commercial polydimethylsiloxane and polyacrylate coatings. The influence of various experimental parameters on the extraction efficiency of UV filters were investigated and optimized. The calibration curves were linear from 0.2 to 200μgL(-1) for each analyte with correlation coefficients above 0.9980. Limits of detection (LODs) and limits of quantitation (LOQs) ranged from 0.03 to 0.05μgL(-1) and from 0.11 to 0.18μgL(-1) for UV filters, respectively. Relative standard deviations (RSDs) for single fiber repeatability ranged from 3.3% to 4.1% (n=5) and RSDs for fiber-to-fiber reproducibility (n=3) varied from 5.7% to 7.7%. The proposed method was successfully applied to the preconcentration and determination of target UV filters in river water and wastewater samples with good recoveries from 86.2% to 113%. Moreover this novel Ti-based fiber is mechanically and chemically stable, and can be easily prepared in a highly reproducible manner.

  18. An enhanced multiwavelength ultraviolet biological trigger lidar

    NASA Astrophysics Data System (ADS)

    Achey, Alexander; Bufton, Jack; Dawson, Jeffrey; Huang, Wen; Lee, Sangmin; Mehta, Nikhil; Prasad, Coorg R.

    2004-12-01

    A compact Ultraviolet Biological Trigger Lidar (UBTL) instrument for detection and discrimination of bio-warfare-agent (BWA) simulant aerosol clouds was developed by us [Prasad, et al, 2004] using a 5mW, 375nm semiconductor UV optical source (SUVOS) laser diode. It underwent successful field tests at Dugway Proving Ground and demonstrated measurement ranges of over 300m for elastic scattering and >100m for fluorescence. The UBTL was modified during mid-2004 to enhance its detection and discrimination performance with increased range of operation and sensitivity. The major optical modifications were: 1. increase in telescope collection aperture to 200 mm diameter: 2. addition of 266nm and 977nm laser transmitters: 3. addition of three detection channels for 266nm and 977nm elastic backscatter and fluorescence centered at 330nm. Also the commercial electronics of the original UBTL were replaced with a multi-channel field programmable gate array (FPGA) chip for laser diode modulation and data acquisition that allowed simultaneous and continuous operation of the UBTL sensor on all of its transmitter and receiver wavelengths. A notebook computer was added for data display and storage. Field tests were performed during July 2004 at the Edgewood Chemical and Biological Center in Maryland to establish the enhanced performance of UBTL subsystems. Results of these tests are presented and discussed.

  19. An elegant route to overcome fundamentally-limited light extraction in AlGaN deep-ultraviolet light-emitting diodes: preferential outcoupling of strong in-plane emission (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Kim, Jong Kyu; Lee, Jong Won; Kim, Dong-Yeong; Park, Jun Hyuk; Schubert, E. Fred; Kim, Jungsub; Kim, Yong-Il

    2016-09-01

    AlGaN-based deep ultraviolet (DUV) light-emitting diodes (LEDs) are being developed for their numerous applications such as purification of air and water, sterilization in food processing, UV curing, medical-, and defense-related light sources. However, external quantum efficiency (EQE) of AlGaN-based DUV LEDs is very poor (<5% for 250nm) particularly due to low hole concentration and light extraction efficiency (LEE). Conventional LEE-enhancing techniques used for GaInN-based visible LEDs turned out to be ineffective for DUV LEDs due to difference in intrinsic material property between GaInN and AlGaN (Al< 30%). Unlike GaInN visible LEDs, DUV light from a high Al-content AlGaN active region is strongly transverse-magnetic (TM) polarized, that is, the electric field vector is parallel to the (0001) c-axis and shows strong sidewall emission through m- or a-plane due to crystal-field split-off hole band being top most valence band. Therefore, a new LEE-enhancing approach addressing the unique intrinsic property of AlGaN DUV LEDs is strongly desired. In this study, an elegant approach based on a DUV LED having multiple mesa stripes whose inclined sidewalls are covered by a MgF2/Al omni-directional mirror to take advantage of the strongly anisotropic transverse-magnetic polarized emission pattern of AlGaN quantum wells is presented. The sidewall-emission-enhanced DUV LED breaks through the fundamental limitations caused by the intrinsic properties of AlGaN, thus shows a remarkable improvement in light extraction as well as operating voltage simultaneously. Furthermore, an analytic model is developed to understand and precisely estimate the extraction of DUV photons from AlGaN DUV LEDs, and hence to provide promising routes to maximize the power conversion efficiency.

  20. Simple and rapid simultaneous profiling of minor components of honey by size exclusion chromatography (SEC) coupled to ultraviolet diode array detection (UV-DAD), combined with chemometric methods.

    PubMed

    Beretta, Giangiacomo; Fermo, Paola; Maffei Facino, Roberto

    2012-01-25

    This paper discusses the importance of profiling UV-responsive components, properly integrated with chemometric techniques, in detecting indicative parameters for quality control of honey. The minor components in honeys of different botanical and geographical origins were investigated by size SEC-UV-DAD. We diluted honey with mobile phase before injection into the chromatographic apparatus and a single chromatographic run gave a fast profile of high- (proteins and enzymes), intermediate- (e.g. terpenoid glycosides in lime tree honey) and low-molecular-weight components (secondary metabolites, e.g. kynurenic acid in chestnut honey). The analysis of a total number of 32 honey samples from different regions (Italy, Western Balkan countries, Brazil, Cameroon, Kenya) and of different botanical origins (herbal flower and arboreal flower nectars/honeydews) showed peculiar and characteristic distribution of these markers, which were basically related to their floral origin. Chemometric examination carried out using principal component analysis (PCA) and hierarchical cluster analysis (HCA) of the chromatograms (RT vs. absorption) detected four main clusters in which the groups of (i) chestnut honeys, (ii) honeys from rain forests and (iii) counterfeit/adulterated honeys were clearly separated from the main group of flower nectar honeys. The method is fast, requiring minimal sample handling, and the chromatographic data can be analyzed by multivariate statistical techniques to obtain descriptive information about the honey's quality and composition.

  1. Ultraviolet Waves

    ERIC Educational Resources Information Center

    Molde, Trevor

    1973-01-01

    Outlines the discovery and nature of ultraviolet light, discusses some applications for these wavelengths, and describes a number of experiments with ultraviolet radiation suitable for secondary school science classes. (JR)

  2. SU-E-T-223: Investigation of the Accuracy of Two-Dimensional Dose Distributions Measurement From High-Dose-Rate Brachytherapy Ir-192 Source Using Multiple-Diode-Array Detector (MapCheck2)

    SciTech Connect

    Taguenang, J; De La Fuente, T Herman; Ahmad, S; Ali, I

    2014-06-01

    Purpose: To investigate the dosimetric accuracy of multiple-diode-array detector (Mapcheck2) for high-dose-rate brachytherapy Ir-192 source. The two-dimensional (2D) dose distributions measured with MapCheck2 were validated with EBT2 Gafchromic film measurement and AAPM task-group- 43 (TG-43) modeling. Methods: 2D-dose distributions from Ir-192 source were measured with MapCheck2 and EBT2-films. MapCheck2 response was corrected for effects: directional dependence, diode and phantom heterogeneity. Optical density growth of the film was controlled by synchronized scanning of the film exposed to Ir-192 and calibration films exposed to 6 MV linac beams. Similarly, MapCheck2 response was calibrated to dose using 6 MV beams. An empirical model was developed for the dose distributions measured with Mapcheck2 that considered directional, diode and phantom heterogeneity corrections. The dose deposited in solid-state-detectors was modeled using a cavity theory model for the diode. This model was then validated with measurements using EBT2-films and calculations with TG-43. Results: The response of MapCheck2 has been corrected for different effects including: (a) directional dependence of 0–20% over angular range 0o–90o, (b) phantom heterogeneity (3%) and (c) diode heterogeneity (9%). The corrected dose distributions measured with MapCheck2 agreed well with the measured dose distributions from EBT2-film and with calculations using TG-43 within 5% over a wide range of dose levels and rates. The advantages of MapCheck2 include less noisy, linear and stable response compared with film. The response of MapCheck2 exposed to 192Ir-source showed no energy dependence similar to its response to MV energy beam. Detection spatial-resolution of individual diodes was 0.8×0.8 mm2, however, 2DMapCheck2 resolution is limited by distance between diodes (7.07 mm). Conclusion: The dose distribution measured with MapCheck2 agreed well within 5% with that measured using EBT2-films; and

  3. Multi-residue determination of eleven anticoagulant rodenticides by high-performance liquid chromatography with diode array/fluorimetric detection: investigation of suspected animal poisoning in the period 2012-2013 in north-eastern Italy.

    PubMed

    Gallocchio, Federica; Basilicata, Lara; Benetti, Cristiana; Angeletti, Roberto; Binato, Giovanni

    2014-11-01

    Misuse or deliberate abuse of anticoagulant rodenticides (AR) may often result in incidental or malicious non-target animal poisoning. This study presents preliminary results of the analysis of 561 real suspected samples, ranging from baits to livers and stomach contents, collected at the Istituto Zooprofilattico Sperimentale delle Venezie (official referral laboratory for the regions of north-eastern Italy), in the period 2012-2013. Samples were analyzed by a method based on a combination of liquid chromatography with diode array/fluorescence detection (HPLC-DAD/F) able to identify 11 different AR (brodifacoum, bromadiolone, chloropahacinone, coumachlor, coumafuryl, coumatetralyl, difenacoum, diphacinone, flocoumafen, pindone, warfarin).

  4. Simultaneous metabolite fingerprinting of hydrophilic and lipophilic compounds in Echinacea pallida by high-performance liquid chromatography with diode array and electrospray ionization-mass spectrometry detection.

    PubMed

    Pellati, Federica; Orlandini, Giulia; Benvenuti, Stefania

    2012-06-15

    In this study, a detailed phytochemical characterization of Echinacea pallida (Nutt.) Nutt. root extracts and dietary supplements was carried out for the first time by developing advanced chromatographic techniques, based on HPLC with diode array (DAD) and electrospray ionization-mass spectrometry (ESI-MS) detection (with ion trap and triple quadrupole mass analyzers), for the simultaneous analysis of hydrophilic and lipophilic secondary metabolites. The HPLC analyses were carried out on an Ascentis C(18) column (250 mm × 4.6 mm I.D., 5 μm), with a mobile phase composed by H(2)O and ACN both containing 0.1% formic acid, under gradient elution. The UV spectra, in combination with MS and MS/MS data, allowed the identification of fourteen compounds, including caffeic acid derivatives, polyacetylenes and polyenes, in the analyzed samples. MS and MS/MS data were discussed in detail and the typical fragmentation patterns of each class of secondary metabolites were identified. For the first time, a hydroperoxide intermediate was characterized as an oxidation product of one of E. pallida monocarbonylic acetylenes, providing a confirmation of the mechanism that leads to the generation of hydroxylated derivatives. The HPLC method was fully validated in agreement with ICH guidelines and then applied to real samples. The quantitative analysis indicated that there was a great variability in the amount of the active compounds in the dietary supplements containing E. pallida root extracts: the content of total caffeic acid derivatives ranged from 2.31 to 11.45 mg/g and the amount of total polyacetylenes and polyenes from 6.38 to 30.54 mg/g. In the analyzed samples, the most abundant caffeic acid derivative was found to be echinacoside. Regarding polyacetylenes and polyenes, the most representative compounds were found to be tetradec-(8Z)-ene-11,13-diyn-2-one, pentedeca-(8Z,11Z)-dien-2-one and pentadec-(8Z)-en-2-one. The developed method can be considered suitable for metabolite

  5. Combination of multivariate curve resolution and multivariate classification techniques for comprehensive high-performance liquid chromatography-diode array absorbance detection fingerprints analysis of Salvia reuterana extracts.

    PubMed

    Hakimzadeh, Neda; Parastar, Hadi; Fattahi, Mohammad

    2014-01-24

    In this study, multivariate curve resolution (MCR) and multivariate classification methods are proposed to develop a new chemometric strategy for comprehensive analysis of high-performance liquid chromatography-diode array absorbance detection (HPLC-DAD) fingerprints of sixty Salvia reuterana samples from five different geographical regions. Different chromatographic problems occurred during HPLC-DAD analysis of S. reuterana samples, such as baseline/background contribution and noise, low signal-to-noise ratio (S/N), asymmetric peaks, elution time shifts, and peak overlap are handled using the proposed strategy. In this way, chromatographic fingerprints of sixty samples are properly segmented to ten common chromatographic regions using local rank analysis and then, the corresponding segments are column-wise augmented for subsequent MCR analysis. Extended multivariate curve resolution-alternating least squares (MCR-ALS) is used to obtain pure component profiles in each segment. In general, thirty-one chemical components were resolved using MCR-ALS in sixty S. reuterana samples and the lack of fit (LOF) values of MCR-ALS models were below 10.0% in all cases. Pure spectral profiles are considered for identification of chemical components by comparing their resolved spectra with the standard ones and twenty-four components out of thirty-one components were identified. Additionally, pure elution profiles are used to obtain relative concentrations of chemical components in different samples for multivariate classification analysis by principal component analysis (PCA) and k-nearest neighbors (kNN). Inspection of the PCA score plot (explaining 76.1% of variance accounted for three PCs) showed that S. reuterana samples belong to four clusters. The degree of class separation (DCS) which quantifies the distance separating clusters in relation to the scatter within each cluster is calculated for four clusters and it was in the range of 1.6-5.8. These results are then

  6. High power coherent polarization locked laser diode.

    PubMed

    Purnawirman; Phua, P B

    2011-03-14

    We have coherently combined a broad area laser diode array to obtain high power single-lobed output by using coherent polarization locking. The single-lobed coherent beam is achieved by spatially combining four diode emitters using walk-off crystals and waveplates while their phases are passively locked via polarization discrimination. While our previous work focused on coherent polarization locking of diode in Gaussian beams, we demonstrate in this paper, the feasibility of the same polarization discrimination for locking multimode beams from broad area diode lasers. The resonator is designed to mitigate the loss from smile effect by using retro-reflection feedback in the cavity. In a 980 nm diode array, we produced 7.2 W coherent output with M2 of 1.5x11.5. The brightness of the diode is improved by more than an order of magnitude.

  7. The evaluation of a 2D diode array in “magic phantom” for use in high dose rate brachytherapy pretreatment quality assurance

    SciTech Connect

    Espinoza, A.; Petasecca, M.; Fuduli, I.; Lerch, M. L. F.; Rosenfeld, A. B.; Howie, A.; Bucci, J.; Corde, S.; Jackson, M.

    2015-02-15

    Purpose: High dose rate (HDR) brachytherapy is a treatment method that is used increasingly worldwide. The development of a sound quality assurance program for the verification of treatment deliveries can be challenging due to the high source activity utilized and the need for precise measurements of dwell positions and times. This paper describes the application of a novel phantom, based on a 2D 11 × 11 diode array detection system, named “magic phantom” (MPh), to accurately measure plan dwell positions and times, compare them directly to the treatment plan, determine errors in treatment delivery, and calculate absorbed dose. Methods: The magic phantom system was CT scanned and a 20 catheter plan was generated to simulate a nonspecific treatment scenario. This plan was delivered to the MPh and, using a custom developed software suite, the dwell positions and times were measured and compared to the plan. The original plan was also modified, with changes not disclosed to the primary authors, and measured again using the device and software to determine the modifications. A new metric, the “position–time gamma index,” was developed to quantify the quality of a treatment delivery when compared to the treatment plan. The MPh was evaluated to determine the minimum measurable dwell time and step size. The incorporation of the TG-43U1 formalism directly into the software allows for dose calculations to be made based on the measured plan. The estimated dose distributions calculated by the software were compared to the treatment plan and to calibrated EBT3 film, using the 2D gamma analysis method. Results: For the original plan, the magic phantom system was capable of measuring all dwell points and dwell times and the majority were found to be within 0.93 mm and 0.25 s, respectively, from the plan. By measuring the altered plan and comparing it to the unmodified treatment plan, the use of the position–time gamma index showed that all modifications made could be

  8. Ultraviolet Light Emitting Diode Optical Power Characterization

    DTIC Science & Technology

    2014-03-01

    which is sbumerged into a 55 gallon fish tank filled with distilled water (reverse osmosis water). To fasten the UV LED chamber inside of the...experiments, the reverse osmosis water used was very similar to distilled water, the oxidation of the metal components in the water did not create a...distilled” and water that is from a reverse osmosis system. The amount of filtration the reverse osmosis system is based on what is desired to be

  9. Ultraviolet laser excitation source

    NASA Technical Reports Server (NTRS)

    Lee, J. H.; Mcfarland, D. R.; Hohl, F.

    1980-01-01

    A new intense ultraviolet light source has been developed from an array of hypocycloidal pinch (HCP) devices. The basic unit of the array is constructed with three disk electrodes and is capable of producing dense plasmas at temperatures up to 10,000,000 K. Very high input power levels to the array are possible without significantly shortening its useful life, in strong contrast with conventional xenon flashlamps. The new light source, when operated with Ar and Xe gas mixtures at high pressures (approximately 5 x 10 to the 4th Pa), produced a light output of over 100 MW in the near-UV spectral range and successfully pumped an iodine photodissociation laser at 1.315 microns. A xenon recombination laser at 2.027 microns was also pumped in the HCP array.

  10. High power, high reliability laser diodes

    NASA Astrophysics Data System (ADS)

    Scifres, D. R.; Welch, D. F.; Craig, R. R.; Zucker, E.; Major, J. S.; Harnagel, G. L.; Sakamoto, M.; Haden, J. M.; Endriz, J. G.; Kung, H.

    1992-06-01

    Results are presented on catastrophic damage limits and life-test measurements for four types of high-power laser diodes operating at wavelengths between 980 nm and 690 nm. The laser diodes under consideration are CW multimode lasers, CW laser bars, quasi-CW bars/2D stacked arrays, and single transverse mode lasers.

  11. Ultraviolet filters.

    PubMed

    Shaath, Nadim A

    2010-04-01

    The chemistry, photostability and mechanism of action of ultraviolet filters are reviewed. The worldwide regulatory status of the 55 approved ultraviolet filters and their optical properties are documented. The photostabilty of butyl methoxydibenzoyl methane (avobenzone) is considered and methods to stabilize it in cosmetic formulations are presented.

  12. Processes for design, construction and utilisation of arrays of light-emitting diodes and light-emitting diode-coupled optical fibres for multi-site brain light delivery

    PubMed Central

    Bernstein, Jacob G.; Allen, Brian D.; Guerra, Alexander A.; Boyden, Edward S.

    2016-01-01

    Optogenetics enables light to be used to control the activity of genetically targeted cells in the living brain. Optical fibers can be used to deliver light to deep targets, and LEDs can be spatially arranged to enable patterned light delivery. In combination, arrays of LED-coupled optical fibers can enable patterned light delivery to deep targets in the brain. Here we describe the process flow for making LED arrays and LED-coupled optical fiber arrays, explaining key optical, electrical, thermal, and mechanical design principles to enable the manufacturing, assembly, and testing of such multi-site targetable optical devices. We also explore accessory strategies such as surgical automation approaches as well as innovations to enable low-noise concurrent electrophysiology. PMID:26798482

  13. Integrated injection-locked semiconductor diode laser

    DOEpatents

    Hadley, G. Ronald; Hohimer, John P.; Owyoung, Adelbert

    1991-01-01

    A continuous wave integrated injection-locked high-power diode laser array is provided with an on-chip independently-controlled master laser. The integrated injection locked high-power diode laser array is capable of continuous wave lasing in a single near-diffraction limited output beam at single-facet power levels up to 125 mW (250 mW total). Electronic steering of the array emission over an angle of 0.5 degrees is obtained by varying current to the master laser. The master laser injects a laser beam into the slave array by reflection of a rear facet.

  14. Integrated injection-locked semiconductor diode laser

    DOEpatents

    Hadley, G.R.; Hohimer, J.P.; Owyoung, A.

    1991-02-19

    A continuous wave integrated injection-locked high-power diode laser array is provided with an on-chip independently-controlled master laser. The integrated injection locked high-power diode laser array is capable of continuous wave lasing in a single near-diffraction limited output beam at single-facet power levels up to 125 mW (250 mW total). Electronic steering of the array emission over an angle of 0.5 degrees is obtained by varying current to the master laser. The master laser injects a laser beam into the slave array by reflection of a rear facet. 18 figures.

  15. Metabolic profiling of nuciferine in rat urine, plasma, bile and feces after oral administration using ultra-high performance liquid chromatography-diode array detection-quadrupole time-of-flight mass spectrometry.

    PubMed

    Wu, Xiao-Lei; Wu, Ming-Jiang; Chen, Xin-Ze; Ma, Hao-Ling; Ding, Li-Qin; Qiu, Feng; Pan, Qin; Zhang, De-Qin

    2017-03-18

    Nuciferine, a major alkaloid found in Nelumbinis Folium, exhibits a broad spectrum of bioactivities, such as antiobesity, anti-diabetes and anti-inflammatory. However, many research regarding nuciferine focused on the extraction, isolation and biological activity, the metabolism is not comprehensively explained in vivo. Thence, the present of this paper is to establish a simple method for speculating metabolites of nuciferine. A total of 15 metabolites were detected and tentatively identified through ultra high performance liquid chromatography-diode array detection-quadrupole time-of-flight mass spectrometry (UHPLC-DAD-QTOF-MS), including 7 new metabolites. Among them, we also discovered a previously unmentioned metabolically active site at the C1-OCH3 position. These metabolites suggested that demethylation, oxidation, glucuronidation and sulfation were major metabolic pathways. This study provided significant experiment basis for its safety estimate and valuable information about the metabolism of nuciferine, which will be advantageous for new drug development.

  16. Simultaneous quantitation of 14 active components in Yinchenhao decoction with an ultrahigh performance liquid chromatography-diode array detector: Method development and ingredient analysis of different commonly prepared samples.

    PubMed

    Yi, YaXiong; Zhang, Yong; Ding, Yue; Lu, Lu; Zhang, Tong; Zhao, Yuan; Xu, XiaoJun; Zhang, YuXin

    2016-11-01

    J. Sep. Sci. 2016, 39, 4147-4157 DOI: 10.1002/jssc.201600284 Yinchenhao decoction (YCHD) is a famous Chinese herbal formula recorded in the Shang Han Lun which was prescribed by Zhongjing Zhang during 150-219 AD. A novel quantitative analysis method was developed, based on ultrahigh performance liquid chromatography coupled with a diode array detector for the simultaneous determination of 14 main active components in Yinchenhao decoction. Furthermore, the method has been applied for compositional difference analysis of the 14 components in eight normal extraction samples of Yinchenhao decoction, with the aid of hierarchical clustering analysis and similarity analysis. The present research could help hospital, factory and lab choose the best way to make Yinchenhao decoction with better efficacy.

  17. Analysis of the influence of processing of stir-baking with glycyrrhizae on the main components of Euodiae Fructus by high-performance liquid chromatography with diode array detector.

    PubMed

    Hu, Jue; Wu, Xin; Cao, Gang; Chen, Xiaocheng

    2014-01-01

    Euodiae Fructus is one of the most commonly used Chinese herbs in China. Specifically, the crude Euodiae Fructus and its processed products of Gancao Zhi Pin are used clinically for the treatment of different diseases. In order to improve the quality control standard and evaluate the crude and processed Euodiae Fructus, in this study, a simple and sensitive high-performance liquid chromatography-diode array detector method was developed for the simultaneous determination of five major compounds in Euodiae Fructus. The results indicated that the five components had significant linear relation (r(2) ≥ 0.9997) between the peak area and the injected concentration. The average recoveries of the five components were in the range from 97.38% to 102.56%. Overall intra- and inter-day variations were less than 1.36%. The developed method can be applied to the intrinsic quality control of crude and processed Euodiae Fructus.

  18. The offline combination of thin-layer chromatography and high-performance liquid chromatography with diode array detection and micrOTOF-Q mass spectrometry for the separation and identification of spinochromes from sea urchin (Strongylocentrotus droebachiensis) shells.

    PubMed

    Shikov, Alexander N; Ossipov, Vladimir I; Martiskainen, Olli; Pozharitskaya, Olga N; Ivanova, Svetlana A; Makarov, Valery G

    2011-12-16

    Thin-layer chromatography (TLC) with off-line high-performance liquid chromatography coupled to diode array detection and micrOTOF-Q mass spectrometry (HPLC-DAD-MS) resulted in the successful fractionation, separation and identification of spinochrome pigments from sea urchin (Strongylocentrotus droebachiensis) shells. Two fractions of pigments were separated by TLC and eluted with methanol using a TLC-MS interface. HPLC-DAD-MS analysis of the fractions indicated the presence of six sea urchin pigments: spinochrome monomers B and D, three spinochrome dimers (anhydroethylidene-6,6'-bis(2,3,7-trihydroxynaphthazarin) and its isomer and ethylidene-6,6'-bis(2,3,7-trihydroxynaphthazarin)), and one pigment that was preliminary identified as a spinochrome dimer with the structural formula C(22)H(16)O(16).

  19. Characterization and quantitative analysis of phenylpropanoid amides in eggplant (Solanum melongena L.) by high performance liquid chromatography coupled with diode array detection and hybrid ion trap time-of-flight mass spectrometry.

    PubMed

    Sun, Jing; Song, Yue-Lin; Zhang, Jing; Huang, Zheng; Huo, Hui-Xia; Zheng, Jiao; Zhang, Qian; Zhao, Yun-Fang; Li, Jun; Tu, Peng-Fei

    2015-04-08

    Eggplant (Solanum melongena L.) is a famous edible and medicinal plant. Despite being widely cultivated and used, data on certain parts other than the fruit are limited. The present study focused on the qualitative and quantitative analysis of the chemical constituents, particularly phenylpropanoid amides (PAs), in eggplant. The mass fragmentation patterns of PAs were proposed using seven authentic compounds with the assistance of a hybrid ion trap time-of-flight mass spectrometer. Thirty-seven compounds (27 PAs and 10 others) were detected and plausibly assigned in the different parts of eggplant. Afterward, a reliable method based on liquid chromatography coupled with diode array detection was developed, validated, and applied for the simultaneous determination of seven PAs and three caffeoylquinic acids in 17 batches of eggplant roots with satisfactory accuracy, precision, and reproducibility, which could not only provide global chemical insight of eggplant but also offer a reliable tool for quality control.

  20. A dosimetric study of a heterogeneous phantom for lung stereotactic body radiation therapy comparing Monte Carlo and pencil beam calculations to dose distributions measured with a 2-D diode array

    NASA Astrophysics Data System (ADS)

    Curley, Casey Michael

    Monte Carlo (MC) and Pencil Beam (PB) calculations are compared to their measured planar dose distributions using a 2-D diode array for lung Stereotactic Body Radiation Therapy (SBRT). The planar dose distributions were studied for two different phantom types: an in-house heterogeneous phantom and a homogeneous phantom. The motivation is to mimic the human anatomy during a lung SBRT treatment and incorporate heterogeneities into the pre-treatment Quality Assurance process, where measured and calculated planar dose distributions are compared before the radiation treatment. Individual and combined field dosimetry has been performed for both fixed gantry angle (anterior to posterior) and planned gantry angle delivery. A gamma analysis has been performed for all beam arrangements. The measurements were obtained using the 2-D diode array MapCHECK 2(TM). MC and PB calculations were performed using the BrainLAB iPlan RTRTM Dose software. The results suggest that with the heterogeneous phantom as a quality assurance device, the MC calculations result in closer agreements to the measured values, when using the planned gantry angle delivery method for composite beams. For the homogeneous phantom, the results suggest that the preferred delivery method is at the fixed anterior to posterior gantry angle. Furthermore, the MC and PB calculations do not show significant differences for dose difference and distance to agreement criteria 3%/3mm. However, PB calculations are in better agreement with the measured values for more stringent gamma criteria when considering individual beam whereas MC agreements are closer for composite beam measurements.