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Sample records for absolute photonic band

  1. Design of two-dimensional photonic crystals with large absolute band gaps using a genetic algorithm

    NASA Astrophysics Data System (ADS)

    Shen, Linfang; Ye, Zhuo; He, Sailing

    2003-07-01

    A two-stage genetic algorithm (GA) with a floating mutation probability is developed to design a two-dimensional (2D) photonic crystal of a square lattice with the maximal absolute band gap. The unit cell is divided equally into many square pixels, and each filling pattern of pixels with two dielectric materials corresponds to a chromosome consisting of binary digits 0 and 1. As a numerical example, the two-stage GA gives a 2D GaAs structure with a relative width of the absolute band gap of about 19%. After further optimization, a new 2D GaAs photonic crystal is found with an absolute band gap much larger than those reported before.

  2. Photonic band gap materials

    SciTech Connect

    Soukoulis, C.M. |

    1993-12-31

    An overview of the theoretical and experimental efforts in obtaining a photonic band gap, a frequency band in three-dimensional dielectric structures in which electromagnetic waves are forbidden, is presented.

  3. Photonic band gap materials

    NASA Astrophysics Data System (ADS)

    Cassagne, D.

    Photonic band gap materials Photonic band gap materials are periodic dielectric structures that control the propagation of electromagnetic waves. We describe the plane wave method, which allows to calculate the band structures of photonic crystals. By symmetry analysis and a perturbative approach, we predict the appearance of the low energy photonic band gaps of hexagonal structures. We propose new two-dimensional structures called graphite and boron nitride. Using a transfer matrix method, we calculate the transmission of the graphite structure and we show the crucial role of the coupling with external modes. We study the appearance of allowed modes in the photonic band gap by the introduction of localized defects in the periodicity. Finally, we discuss the properties of opals formed by self-organized silica microspheres, which are very promising for the fabrication of three-dimensional photonic crystals. Les matériaux à bandes interdites photoniques sont des structures diélectriques périodiques qui contrôlent la propagation des ondes électromagnétiques. Nous décrivons la méthode des ondes planes qui permet de calculer les structures de bandes des cristaux photoniques. Par une analyse de la symétrie et une approche perturbative, nous précisons les conditions d'existence des bandes interdites de basse énergie. Nous proposons de nouvelles structures bidimensionnelles appelées graphite et nitrure de bore. Grâce à une méthode de matrices de transfert, nous calculons la transmission de la structure graphite et nous mettons en évidence le rôle fondamental du couplage avec les modes extérieurs. Nous étudions l'apparition de modes permis dans la bande interdite grâce à l'introduction de défauts dans la périodicité. Enfin, nous discutons les propriétés des opales constituées de micro-billes de silice auto-organisées, qui sont très prometteuses pour la fabrication de cristaux photoniques tridimensionnels.

  4. Photonic band structure

    SciTech Connect

    Yablonovitch, E.

    1993-05-01

    We learned how to create 3-dimensionally periodic dielectric structures which are to photon waves, as semiconductor crystals are to electron waves. That is, these photonic crystals have a photonic bandgap, a band of frequencies in which electromagnetic waves are forbidden, irrespective of propagation direction in space. Photonic bandgaps provide for spontaneous emission inhibition and allow for a new class of electromagnetic micro-cavities. If the perfect 3-dimensional periodicity is broken by a local defect, then local electromagnetic modes can occur within the forbidden bandgap. The addition of extra dielectric material locally, inside the photonic crystal, produces {open_quotes}donor{close_quotes} modes. Conversely, the local removal of dielectric material from the photonic crystal produces {open_quotes}acceptor{close_quotes} modes. Therefore, it will now be possible to make high-Q electromagnetic cavities of volume {approx_lt}1 cubic wavelength, for short wavelengths at which metallic cavities are useless. These new dielectric micro-resonators can cover the range all the way from millimeter waves, down to ultraviolet wavelengths.

  5. Photonic Band Engineering

    NASA Astrophysics Data System (ADS)

    Yabonovitch, Eli

    2001-09-01

    Scientists at UCLA, Caltech, and Polytechnic University have developed a new concept in Electromagnetics called "Photonic Bandgaps' that permits unprecedented control of Electromagnetic Waves, at both radio frequencies, and optical frequencies. This new paradigm of Electromagnetics is based on Nature's design for semiconductor crystals, but it is a crystal structure that is artificially engineered for electromagnetic waves rather than for electron waves. Beginning in 1996, new frontiers in the engineered control of electromagnetic waves have emerged from this design paradigm. For example, the very tiniest, most miniaturized electromagnetic cavity ever created was engineered, and demonstrated, under this MURI; trapping optical energy in the smallest volume ever achieved. This world's most tiny light trap was also made into the most miniaturized laser ever made, occupying a volume smaller than a cubic wavelength. At the same time this MURI advanced the electromagnetic bandgap concept into microwaves and radio waves that are so important for military systems. This required new concepts that permitted the bandgap structure to be much smaller than the electromagnetic wavelength. As in the optical version of photonic crystals, these electromagnetic bandgaps permit unprecedented control over radio frequency electromagnetic waves. For example new antenna structures have been invented that permit near field control over radio emissions from antennas, so that the hand-held radio transmitters can be more efficient.

  6. Photonic band gap structure simulator

    DOEpatents

    Chen, Chiping; Shapiro, Michael A.; Smirnova, Evgenya I.; Temkin, Richard J.; Sirigiri, Jagadishwar R.

    2006-10-03

    A system and method for designing photonic band gap structures. The system and method provide a user with the capability to produce a model of a two-dimensional array of conductors corresponding to a unit cell. The model involves a linear equation. Boundary conditions representative of conditions at the boundary of the unit cell are applied to a solution of the Helmholtz equation defined for the unit cell. The linear equation can be approximated by a Hermitian matrix. An eigenvalue of the Helmholtz equation is calculated. One computation approach involves calculating finite differences. The model can include a symmetry element, such as a center of inversion, a rotation axis, and a mirror plane. A graphical user interface is provided for the user's convenience. A display is provided to display to a user the calculated eigenvalue, corresponding to a photonic energy level in the Brilloin zone of the unit cell.

  7. Absolute photon-flux measurements in the vacuum ultraviolet

    NASA Technical Reports Server (NTRS)

    Samson, J. A. R.; Haddad, G. N.

    1974-01-01

    Absolute photon-flux measurements in the vacuum ultraviolet have extended to short wavelengths by use of rare-gas ionization chambers. The technique involves the measurement of the ion current as a function of the gas pressure in the ion chamber. The true value of the ion current, and hence the absolute photon flux, is obtained by extrapolating the ion current to zero gas pressure. Examples are given at 162 and 266 A. The short-wavelength limit is determined only by the sensitivity of the current-measuring apparatus and by present knowledge of the photoionization processes that occur in the rate gases.

  8. Optimization of band gaps of 2D photonic crystals by the rapid generic algorithm

    NASA Astrophysics Data System (ADS)

    Sun, Yun-tao

    2011-01-01

    Based on the rapid genetic algorithm (RGA), the band gap structures of square lattices with square scatters are optimized. In the optimizing process, gene codes are used to express square scatters and the fitting function adopts the relative values of the largest absolute photonic band gaps (PBGs). By changing the value of filling factor, three cell forms with large photonic band gaps are obtained. In addition, the comparison between the rapid genetic algorithm and the general genetic algorithm (GGA) is analyzed.

  9. Landsat-5 TM reflective-band absolute radiometric calibration

    USGS Publications Warehouse

    Chander, G.; Helder, D.L.; Markham, B.L.; Dewald, J.D.; Kaita, E.; Thome, K.J.; Micijevic, E.; Ruggles, T.A.

    2004-01-01

    The Landsat-5 Thematic Mapper (TM) sensor provides the longest running continuous dataset of moderate spatial resolution remote sensing imagery, dating back to its launch in March 1984. Historically, the radiometric calibration procedure for this imagery used the instrument's response to the Internal Calibrator (IC) on a scene-by-scene basis to determine the gain and offset of each detector. Due to observed degradations in the IC, a new procedure was implemented for U.S.-processed data in May 2003. This new calibration procedure is based on a lifetime radiometric calibration model for the instrument's reflective bands (1-5 and 7) and is derived, in part, from the IC response without the related degradation effects and is tied to the cross calibration with the Landsat-7 Enhanced Thematic Mapper Plus. Reflective-band absolute radiometric accuracy of the instrument tends to be on the order of 7% to 10%, based on a variety of calibration methods.

  10. Photonic band gap in thin wire metamaterials.

    PubMed

    Hock, Kai Meng

    2008-03-01

    We investigate the band structure of a class of photonic crystals made from only thin wires. Using a different method, we demonstrate that a complete photonic band gap is possible for such materials. Band gap materials normally consist of space filling dielectric or metal, whereas thin wires occupy a very small fraction of the volume. We show that this is related to the large increase in scattering at the Brillouin zone boundary. The method we developed brings together the calculation techniques in three different fields. The first is the calculation of scattering from periodic, tilted antennas, which we improve upon. The second is the standard technique for frequency selective surface design. The third is obtained directly from low energy electron diffraction theory. Good agreements with experiments for left handed materials, negative materials, and frequency selective surfaces are demonstrated.

  11. Effect of size of silica microspheres on photonic band gap

    SciTech Connect

    Dhiman, N. Sharma, A. Gathania, A. K.; Singh, B. P.

    2014-04-24

    In present work photonic crystals of different size of silica microspheres have been fabricated. The optical properties of these developed photonic crystals have been studied using UV-visible spectroscopy. UV-visible spectroscopy shows that they have photonic band gap that can be tuned in visible and infrared regime by changing the size of silica microspheres. The photonic band gap structures of these photonic crystals have been calculated using MIT photonic band gap package. It also reveals that with the increase in size of silica microspheres the photonic band gap shifts to lower energy region.

  12. Absolute analytical prediction of photonic crystal guided mode resonance wavelengths

    SciTech Connect

    Hermannsson, Pétur Gordon; Vannahme, Christoph; Smith, Cameron L. C.; Kristensen, Anders

    2014-08-18

    A class of photonic crystal resonant reflectors known as guided mode resonant filters are optical structures that are widely used in the field of refractive index sensing, particularly in biosensing. For the purposes of understanding and design, their behavior has traditionally been modeled numerically with methods such as rigorous coupled wave analysis. Here it is demonstrated how the absolute resonance wavelengths of such structures can be predicted by analytically modeling them as slab waveguides in which the propagation constant is determined by a phase matching condition. The model is experimentally verified to be capable of predicting the absolute resonance wavelengths to an accuracy of within 0.75 nm, as well as resonance wavelength shifts due to changes in cladding index within an accuracy of 0.45 nm across the visible wavelength regime in the case where material dispersion is taken into account. Furthermore, it is demonstrated that the model is valid beyond the limit of low grating modulation, for periodically discontinuous waveguide layers, high refractive index contrasts, and highly dispersive media.

  13. Fabrication of Photonic band gap Materials

    SciTech Connect

    Constant, Kristen; Subramania, Ganapathi S.; Biswas, Rana; Ho, Kai-Ming

    2000-01-05

    A method for forming a periodic dielectric structure exhibiting photonic band gap effects includes forming a slurry of a nano-crystalline ceramic dielectric or semiconductor material and monodisperse polymer microsphere, depositing a film of the slurry on a substrate, drying the film, and calcining the film to remove the polymer microsphere there from. The film may be cold-pressed after drying and prior to calcining. The ceramic dielectric or semiconductor material may be titania, and the polymer microsphere may be polystyrenemicrosphere.

  14. Fabrication of photonic band gap materials

    DOEpatents

    Constant, Kristen; Subramania, Ganapathi S.; Biswas, Rana; Ho, Kai-Ming

    2002-01-15

    A method for forming a periodic dielectric structure exhibiting photonic band gap effects includes forming a slurry of a nano-crystalline ceramic dielectric or semiconductor material and monodisperse polymer microspheres, depositing a film of the slurry on a substrate, drying the film, and calcining the film to remove the polymer microspheres therefrom. The film may be cold-pressed after drying and prior to calcining. The ceramic dielectric or semiconductor material may be titania, and the polymer microspheres may be polystyrene microspheres.

  15. Phase Modulation of Photonic Band Gap Signal

    PubMed Central

    Wang, Zhiguo; Gao, Mengqin; Mahesar, Abdul Rasheed; Zhang, Yanpeng

    2016-01-01

    We first investigate the probe transmission signal (PTS) and the four wave mixing band gap signal (FWM BGS) modulated simultaneously by the relative phase and the nonlinear phase shift in the photonic band gap (PBG) structure. The switch between the absorption enhancement of PTS and the transmission enhancement of PTS with the help of changing the relative phase and the nonlinear phase shift is obtained in inverted Y-type four level atomic system experimentally and theoretically. The corresponding switch in PTS can be used to realize all optical switches. On other hand, the relative phase and the nonlinear phase shift also play the vital role to modulate the intensity of FWM BGS reflected from the PBG structure. And it can be potentially used to realize the optical amplifier. PMID:27323849

  16. Analysis of photonic band gaps in two-dimensional photonic crystals with rods covered by a thin interfacial layer

    SciTech Connect

    Trifonov, T.; Marsal, L.F.; Pallares, J.; Rodriguez, A.; Alcubilla, R.

    2004-11-15

    We investigate different aspects of the absolute photonic band gap (PBG) formation in two-dimensional photonic structures consisting of rods covered with a thin dielectric film. Specifically, triangular and honeycomb lattices in both complementary arrangements, i.e., air rods drilled in silicon matrix and silicon rods in air, are studied. We consider that the rods are formed of a dielectric core (silicon or air) surrounded by a cladding layer of silicon dioxide (SiO{sub 2}), silicon nitride (Si{sub 3}N{sub 4}), or germanium (Ge). Such photonic lattices present absolute photonic band gaps, and we study the evolution of these gaps as functions of the cladding material and thickness. Our results show that in the case of air rods in dielectric media the existence of dielectric cladding reduces the absolute gap width and may cause complete closure of the gap if thick layers are considered. For the case of dielectric rods in air, however, the existence of a cladding layer can be advantageous and larger absolute PBG's can be achieved.

  17. Modeling of Photonic Band Gap Crystals and Applications

    SciTech Connect

    Ihab Fathy El-Kady

    2002-08-27

    research that involves the interplay of metallic-PBG rejection and photonic band edge absorption. They propose that an absolute metallic-PBG may be used to suppress the infrared part of the blackbody emission and, emit its energy only through a sharp absorption band. Potential applications of this new PBG mechanism include highly efficient incandescent lamps and enhanced thermophotovoltaic energy conversion. The suggested lamp would be able to recycle the energy that would otherwise go into the unwanted heat associated with usual lamps, into light emitted in the visible spectrum. It is estimated this would increase the efficiency over conventional lamps by about 40%.

  18. Comparative studies on photonic band structures of diamond and hexagonal diamond using the multiple scattering method

    NASA Astrophysics Data System (ADS)

    Chen, Hui; Zhang, Weiyi; Wang, Zhenlin

    2004-02-01

    Photonic band structures are investigated for both diamond and hexagonal diamond crystals composed of dielectric spheres, and absolute photonic band gaps (PBGs) are found in both cases. In agreement with both Karathanos and Moroz's calculations, a large PBG occurs between the eighth and ninth bands in diamond crystal, but a PBG in hexagonal diamond crystal is found to occur between the sixteenth and seventeenth bands because of the doubling of dielectric spheres in the primitive cell. To explore the physical mechanism of how the photonic band gap might be broadened, we have compared the electric field distributions (|E|2) of the 'valence' and 'conduction' band edges. Results show that the field intensity for the 'conduction' band locates in the inner core of the sphere while that of the 'valence' band concentrates in the outer shell. With this motivation, double-layer spheres are designed to enhance the corresponding photonic band gaps; the PBG is increased by 35% for the diamond structure, and 14% for the hexagonal diamond structure.

  19. Highly dispersive photonic band-gap-edge optofluidic biosensors

    NASA Astrophysics Data System (ADS)

    Xiao, S.; Mortensen, N. A.

    2006-11-01

    Highly dispersive photonic band-gap-edge optofluidic biosensors are studied theoretically. We demonstrate that these structures are strongly sensitive to the refractive index of the liquid, which is used to tune dispersion of the photonic crystal. The upper frequency band-gap edge shifts about 1.8 nm for δ n=0.002, which is quite sensitive. Results from transmission spectra agree well with those obtained from the band structure theory.

  20. Thermal properties and two-dimensional photonic band gaps

    NASA Astrophysics Data System (ADS)

    Elsayed, Hussein A.; El-Naggar, Sahar A.; Aly, Arafa H.

    2014-03-01

    The effect of temperature on a two-dimensional square lattice photonic crystal composed of Si rods arranged in an air background was investigated theoretically using the plane-wave expansion method. Both the thermal expansion effect and thermo-optical effect are considered simultaneously. We have discussed the role of temperature in creating the complete photonic band gap as a function of temperature. Two different shapes of rods, i.e. square and circular, are considered in the presence of the two polarization states, i.e. TE and TM waves. The numerical results show that the photonic band gap can be significantly enlarged compared to the photonic band gap at room temperature. The effect of temperature on the complete photonic band width in the cylindrical rods case is more significant. Cylindrical and square Si rods may work as a temperature sensor or filter, among many other potential applications.

  1. Prelaunch absolute radiometric calibration of the reflective bands on the LANDSAT-4 protoflight Thematic Mapper

    NASA Technical Reports Server (NTRS)

    Barker, J. L.; Ball, D. L.; Leung, K. C.; Walker, J. A.

    1984-01-01

    The results of the absolute radiometric calibration of the LANDSAT 4 thematic mapper, as determined during pre-launch tests with a 122 cm integrating sphere, are presented. Detailed results for the best calibration of the protoflight TM are given, as well as summaries of other tests performed on the sensor. The dynamic range of the TM is within a few per cent of that required in all bands, except bands 1 and 3. Three detectors failed to pass the minimum SNR specified for their respective bands: band 5, channel 3 (dead), band 2, and channels 2 and 4 (noisy or slow response). Estimates of the absolute calibration accuracy for the TM show that the detectors are typically calibrated to 5% absolute error for the reflective bands; 10% full-scale accuracy was specified. Ten tests performed to transfer the detector absolute calibration to the internal calibrator show a 5% range at full scale in the transfer calibration; however, in two cases band 5 showed a 10% and a 7% difference.

  2. Absolute calibration of photon-number-resolving detectors with an analog output using twin beams

    SciTech Connect

    Peřina, Jan; Haderka, Ondřej; Allevi, Alessia; Bondani, Maria

    2014-01-27

    A method for absolute calibration of a photon-number resolving detector producing analog signals as the output is developed using a twin beam. The method gives both analog-to-digital conversion parameters and quantum detection efficiency for the photon fields. Characteristics of the used twin beam are also obtained. A simplified variant of the method applicable to fields with high signal to noise ratios and suitable for more intense twin beams is suggested.

  3. Absolute linestrengths in the H2O2 nu6 band

    NASA Technical Reports Server (NTRS)

    May, Randy D.

    1991-01-01

    Absolute linestrengths at 295 K have been measured for selected lines in the nu6 band of H2O2 using a tunable diode-laser spectrometer. H2O2 concentrations in a flowing gas mixture were determined by ultraviolet (uv) absorption at 254 nm using a collinear infrared (ir) and uv optical arrangement. The measured linestrengths are approx. 60 percent larger than previously reported values when absorption by hot bands in H2O2 is taken into account.

  4. Absolute Instability near the Band Edge of Traveling-Wave Amplifiers

    NASA Astrophysics Data System (ADS)

    Hung, D. M. H.; Rittersdorf, I. M.; Zhang, P.; Chernin, D.; Lau, Y. Y.; Antonsen, T. M.; Luginsland, J. W.; Simon, D. H.; Gilgenbach, R. M.

    2015-09-01

    Applying the Briggs-Bers "pole-pinch" criterion to the exact transcendental dispersion relation of a dielectric traveling wave tube (TWT), we find that there is no absolute instability regardless of the beam current. We extend this analysis to the circuit band edges of a linear beam TWT by approximating the circuit mode as a hyperbola in the frequency-wave-number (ω -k ) plane and consider the weak coupling limit. For an operating mode whose group velocity is in the same direction as the beam mode, we find that the lower band edge is not subjected to absolute instability. At the upper band edge, we find a threshold beam current beyond which absolute instability is excited. The nonexistence of absolute instability in a linear beam TWT and the existence in a gyrotron TWT, both at the lower band edge, is contrasted. The general study given here is applicable to some contemporary TWTs such as metamaterial-based and advanced Smith-Purcell TWTs.

  5. Absolute Instability near the Band Edge of Traveling-Wave Amplifiers.

    PubMed

    Hung, D M H; Rittersdorf, I M; Zhang, P; Chernin, D; Lau, Y Y; Antonsen, T M; Luginsland, J W; Simon, D H; Gilgenbach, R M

    2015-09-18

    Applying the Briggs-Bers "pole-pinch" criterion to the exact transcendental dispersion relation of a dielectric traveling wave tube (TWT), we find that there is no absolute instability regardless of the beam current. We extend this analysis to the circuit band edges of a linear beam TWT by approximating the circuit mode as a hyperbola in the frequency-wave-number (ω-k) plane and consider the weak coupling limit. For an operating mode whose group velocity is in the same direction as the beam mode, we find that the lower band edge is not subjected to absolute instability. At the upper band edge, we find a threshold beam current beyond which absolute instability is excited. The nonexistence of absolute instability in a linear beam TWT and the existence in a gyrotron TWT, both at the lower band edge, is contrasted. The general study given here is applicable to some contemporary TWTs such as metamaterial-based and advanced Smith-Purcell TWTs.

  6. Absolute Instability near the Band Edge of Traveling-Wave Amplifiers.

    PubMed

    Hung, D M H; Rittersdorf, I M; Zhang, P; Chernin, D; Lau, Y Y; Antonsen, T M; Luginsland, J W; Simon, D H; Gilgenbach, R M

    2015-09-18

    Applying the Briggs-Bers "pole-pinch" criterion to the exact transcendental dispersion relation of a dielectric traveling wave tube (TWT), we find that there is no absolute instability regardless of the beam current. We extend this analysis to the circuit band edges of a linear beam TWT by approximating the circuit mode as a hyperbola in the frequency-wave-number (ω-k) plane and consider the weak coupling limit. For an operating mode whose group velocity is in the same direction as the beam mode, we find that the lower band edge is not subjected to absolute instability. At the upper band edge, we find a threshold beam current beyond which absolute instability is excited. The nonexistence of absolute instability in a linear beam TWT and the existence in a gyrotron TWT, both at the lower band edge, is contrasted. The general study given here is applicable to some contemporary TWTs such as metamaterial-based and advanced Smith-Purcell TWTs. PMID:26430996

  7. Absolute line intensities in CO2 bands near 4.8 microns

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Benner, D. C.; Devi, V. M.

    1986-01-01

    Absolute intensities for 726 unblended lines in 20 bands of C-12(O-16)2, C-13(O-16)2, O-16C-12O-18, and O-16C-12O-17 in the 4.8-micron spectral region have been determined using a natural sample of ultrahigh-purity CO2. Spectral data were recorded at low pressure (less than 10 torr) and room temperature with the Fourier transform spectrometer in the McMath solar telescope complex on Kitt Peak. Derived vibrational band intensities and coefficients of the F factor for each band were compared to values of the 1982 Air Force Geophysics Laboratory line parameters compilation. The present work fills out the CO2 lines in the 5-micron band systems. Lines in the strongest of these measured bands are being used to infer atmospheric pressure from high-resolution stratospheric spectra recorded during the Spacelab 3 Atmospheric Trace Molecule Spectroscopy experiment.

  8. Photonic band-edge-induced enhancement in absorption and emission

    NASA Astrophysics Data System (ADS)

    Ummer, Karikkuzhi Variyath; Vijaya, Ramarao

    2015-01-01

    An enhancement in photonic band-edge-induced absorption and emission from rhodamine-B dye doped polystyrene pseudo gap photonic crystals is studied. The band-edge-induced enhancement in absorption is achieved by selecting the incident angle of the excitation beam so that the absorption spectrum of the emitter overlaps the photonic band edge. The band-edge-induced enhancement in emission, on the other hand, is possible with and without an enhancement in band-edge-induced absorption, depending on the collection angle of emission. Through a simple set of measurements with suitably chosen angles for excitation and emission, we achieve a maximum enhancement of 70% in emission intensity with band-edge-induced effects over and above the intrinsic emission in the case of self-assembled opals. This is a comprehensive effort to interpret tunable lasing in opals as well as to predict the wavelength of lasing arising as a result of band-edge-induced distributed feedback effects.

  9. Special purpose modes in photonic band gap fibers

    DOEpatents

    Spencer, James; Noble, Robert; Campbell, Sara

    2013-04-02

    Photonic band gap fibers are described having one or more defects suitable for the acceleration of electrons or other charged particles. Methods and devices are described for exciting special purpose modes in the defects including laser coupling schemes as well as various fiber designs and components for facilitating excitation of desired modes. Results are also presented showing effects on modes due to modes in other defects within the fiber and due to the proximity of defects to the fiber edge. Techniques and devices are described for controlling electrons within the defect(s). Various applications for electrons or other energetic charged particles produced by such photonic band gap fibers are also described.

  10. Influence of structural parameters on tunable photonic band gaps modulated by liquid crystals

    NASA Astrophysics Data System (ADS)

    Huang, Aiqin; Zheng, Jihong; Jiang, Yanmeng; Zhou, Zengjun; Tang, Pingyu; Zhuang, Songlin

    2011-10-01

    Tunable photonic crystals (PCs), which are infiltrated with nematic liquid crystals (LCs), tune photonic band gap (PBG) by rotating directors of LCs when applied with the external electrical field. Using the plane wave expansion method, we simulated the PBG structure of two-dimensional tunable PCs with a triangular lattice of circular column, square column and hexagon column, respectively. When PCs are composed of LCs and different substrate materials such as germanium (Ge) and silicon (Si), the influence of structural parameters including column shape and packing ration on PBG is discussed separately. Numerical simulations show that absolute PBG can't be found at any conditions, however large tuning range of polarized wave can be achieved by rotating directors of LCs. The simulation results provide theoretical guidance for the fabrication of field-sensitive polarizer with big tunable band range.

  11. Flat photonic surface bands pinned between Dirac points.

    PubMed

    Jukić, Dario; Buljan, Hrvoje; Lee, Dung-Hai; Joannopoulos, John D; Soljačić, Marin

    2012-12-15

    We point out that 2D photonic crystals (PhCs) can support surface bands that are pinned to Dirac points. These bands can be made very flat by optimizing the parameters of the system. Surface modes are found at the interface of two different cladding materials: one is a PhC with Dirac linear dispersion for the TE mode, and the other is a PhC that has a broad TE gap at the Dirac frequency. PMID:23258072

  12. Absolute intensity measurement of the 4-0 vibration-rotation band of carbon monoxide

    NASA Technical Reports Server (NTRS)

    Chackerian, C., Jr.; Valero, F. P. J.

    1976-01-01

    The absolute intensity of the 4-0 vibration band of CO is measured in spectra obtained using a 25-m base-path multiple-traversal absorption cell and a 5-m scanning spectrometer. The intensities of individual vibration-rotation lines in this band are determined from measurements of their equivalent widths, and absolute values for the rotationless transition moment and the vibration-rotation interaction factor are derived from the measured line strengths. The experimentally obtained vibration-rotation function is compared with a theoretical curve; agreement between theory and experiment is found to be good for the P-branch but poor for the R-branch. It is noted that numerical solutions to the radial Schroedinger equation lead to vibration-rotation function values that are in good agreement with the experiment.

  13. Precise Measurement of the Absolute Yield of Fluorescence Photons in Atmospheric Gases

    SciTech Connect

    Ave, M.; Bohacova, M.; Daumiller, K.; Di Carlo, P.; Di Giulio, C.; Luis, P.Facal San; Gonzales, D.; Hojvat, C.; Horandel, J.R.; Hrabovsky, M.; Iarlori, M.; /INFN, Aquila /Karlsruhe, Inst. Technol.

    2011-01-01

    We have performed a measurement of the absolute yield of fluorescence photons at the Fermilab Test Beam. A systematic uncertainty at 5% level was achieved by the use of Cherenkov radiation as a reference calibration light source. A cross-check was performed by an independent calibration using a laser light source. A significant improvement on the energy scale uncertainty of Ultra-High Energy Cosmic Rays is expected.

  14. Quantum interference of independently generated telecom-band single photons

    SciTech Connect

    Patel, Monika; Altepeter, Joseph B.; Huang, Yu-Ping; Oza, Neal N.; Kumar, Prem

    2014-12-04

    We report on high-visibility quantum interference of independently generated telecom O-band (1310 nm) single photons using standard single-mode fibers. The experimental data are shown to agree well with the results of simulations using a comprehensive quantum multimode theory without the need for any fitting parameter.

  15. W-band active imaging by photonics-based synthesizer

    NASA Astrophysics Data System (ADS)

    Kanno, Atsushi; Sekine, Norihiko; Kasamatsu, Akifumi; Yamamoto, Naokatsu

    2016-05-01

    We demonstrate a nondestructive electromagnetic-wave imaging system with a photonics-based W-band synthe- sizer, traveling-wave tube amplifier and focal-plane transistor array in real time manner. High-power amplifier with multi-watts output will enhance the quality of obtained images under transmission and reflection imaging configurations.

  16. Millimeter-wave waveguiding using photonic band structures

    NASA Astrophysics Data System (ADS)

    Eliyahu, Danny; Sadovnik, Lev S.; Manasson, Vladimir A.

    2000-07-01

    Current trends in device miniaturization and integration, especially in the development of microwave monolithic integrated circuits, calls for flexible, arbitrarily shaped and curved interconnects. Standard dielectric waveguides and microstrip lines are subject to prohibitive losses and their functionality is limited because of their unflexible structures. The problem is addressed by confining the wave- guiding path in a substrate with a Photonic Band Gap structure in a manner that will result in the guided mode being localized within the band gap. Two devices implementing Photonic Band Structures for millimeter waves confinement are presented. The first waveguide is a linear defect in triangular lattice created in a silicon slab (TE mode). The structure consists of parallel air holes of circular cross sections. The silicon was laser drilled to create the 2D crystal. The second device consists of alumina rods arranged in a triangular lattice, surrounded by air and sandwiched between two parallel metal plates (TM mode). Electromagnetic wave (W-band) confinement was obtained in both devices for straight and bent waveguides. Three branch waveguides (intersecting line defects) was studied as well. Measurements confirmed the lowloss waveguide confinement property of the utilizing Photonic Band Gap structure. This structure can find applications in power combiner/splitter and other millimeter wave devices.

  17. Photonic crystal composites-based wide-band optical collimator

    NASA Astrophysics Data System (ADS)

    Shi, Jinjie; Juluri, Bala Krishna; Lin, Sz-Chin Steven; Lu, Mengqian; Gao, Tieyu; Huang, Tony Jun

    2010-08-01

    Photonic crystal (PC) composites are sequenced series of PCs that feature the same periods but different filling fractions. By properly tuning the filling fractions of the individual PCs and merging the working band of each PC into a continuous frequency range, wide-band self-collimation of optical signals can be realized. The band diagrams and the equal-frequency contours of the PC structures were calculated through the plane wave expansion method and the finite-difference time-domain method was employed to simulate the propagation of electromagnetic waves through the PC structures. Our results show that while a single PC can only collimate optical waves over a narrow frequency range, a PC composite exhibits a much wider collimation band. Such a wide-band optical collimation lens can be useful in applications that demand directional optical energy flow over a long distance, such as optical imaging and biosensing.

  18. Absolute intensity measurements of CO2 bands in the 2395-2680/cm region

    NASA Technical Reports Server (NTRS)

    Malathy Devi, V.; Benner, D. C.; Rinsland, C. P.

    1984-01-01

    Absolute intensities for over 800 transitions belonging to twelve bands of (C-12)(O-16)2, (O-16)(C-12)(O-18), (O-16)(C-12)(O-17), and (O-16)(C-13)(O-18) molecules in the 2395-2680/cm spectral region have been derived using a nonlinear least-squares spectral fitting procedure. The data used in the analysis were recorded at room temperature and low pressure with the 0.01/cm resolution Fourier transform spectrometer in the McMath solar telescope complex at the National Solar Observatory. The measured intensities obtained for each band have been analyzed to derive the vibrational band intensity and F-factor coefficients. The results are compared with other published values.

  19. Measurements of absolute line intensities in carbon dioxide bands near 5.2 microns

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Benner, D. C.; Devi, V. M.

    1985-01-01

    A nonlinear least-squares spectral fitting procedure has been used to derive experimental absolute intensities for over 300 unblended lines belonging to twelve CO2 bands in the 5.2-micron region. The spectral data were recorded at 0.01/cm resolution and room temperature with the Fourier transform spectrometer in the McMath solar telescope complex at the National Solar Observatory on Kitt Peak and have a signal-to-rms noise ratio of 2000-4000. A natural sample of carbon dioxide was used as the sample gas. For each band, the measured line intensities have been analyzed to derive the vibrational band intensity and coefficients of the F factor. The results are compared to the values used to calculate the intensities in the 1982 Air Force Geophysics Laboratory line parameters compilation.

  20. Landsat-7 ETM+ on-orbit reflective-band radiometric stability and absolute calibration

    USGS Publications Warehouse

    Markham, B.L.; Thome, K.J.; Barsi, J.A.; Kaita, E.; Helder, Dennis L.; Barker, J. L.; Scaramuzza, Pat

    2004-01-01

    Launched in April 1999, the Landsat-7 Enhanced Thematic Mapper Plus (ETM+) instrument is in its sixth year of operation. The ETM+ instrument has been the most stable of any of the Landsat instruments. To date, the best onboard calibration source for the reflective bands has been the Full Aperture Solar Calibrator, a solar-diffuser-based system, which has indicated changes of between 1% to 2% per year in the ETM+ gain for bands 1-4 and 8 and less than 0.5%/year for bands 5 and 7. However, most of this change is believed to be caused by changes in the solar diffuser panel, as opposed to a change in the instrument's gain. This belief is based partially on vicarious calibrations and observations of "invariant sites", hyperarid sites of the Sahara and Arabia. Weighted average slopes determined from these datasets suggest changes of 0.0% to 0.4% per year for bands 1-4 and 8 and 0.4% to 0.5% per year for bands 5 and 7. Absolute calibration of the reflective bands of the ETM+ is consistent with vicarious observations and other sensors generally at the 5% level, though there appear to be some systematic differences.

  1. Coupling between Fano and Bragg bands in the photonic band structure of two-dimensional metallic photonic structures

    NASA Astrophysics Data System (ADS)

    Markoš, P.; Kuzmiak, V.

    2016-09-01

    The frequency and transmission spectrum of a two-dimensional array of metallic rods is investigated numerically. Based on the recent analysis of the band structure of two-dimensional photonic crystals with dielectric rods [Phys. Rev. A 92, 043814 (2015), 10.1103/PhysRevA.92.043814], we identify two types of bands in the frequency spectrum: Bragg (P ) bands resulting from a periodicity and Fano (F ) bands which arise from Fano resonances associated with each of the cylinders within the periodic structure. It is shown that the existence of the Fano band in a certain frequency range is manifested by a Fano resonance in the transmittance. In particular, we reexamine the symmetry properties of the H -polarized band structure in the frequency range where the spectrum consists of the localized modes associated with the single-scatterer resonances and we explore the process of formation of Fano bands by identifying individual terms in the expansion of the linear combination of atomic orbitals states. We demonstrate how the interplay between the two scattering mechanisms affects the properties of the resulting band structure when the radius of cylinders is increased. We show that a different character of both kinds of bands is reflected in the spatial distribution of the magnetic field, which displays patterns corresponding to the corresponding irreducible symmetry representations.

  2. Two-pattern compound photonic crystals with a large complete photonic band gap

    SciTech Connect

    Jia Lin; Thomas, Edwin L.

    2011-09-15

    We present a set of two-dimensional aperiodic structures with a large complete photonic band gap (PBG), which are named two-pattern photonic crystals. By superposing two substructures without regard to registration, we designed six new aperiodic PBG structures having a complete PBG larger than 15% for {epsilon}{sub 2}/{epsilon}{sub 1} = 11.4. The rod-honeycomb two-pattern photonic crystal provides the largest complete PBG to date. An aperiodic structure becomes the champion structure with the largest PBG. Surprisingly, the TM and TE gaps of a two-pattern photonic crystal are much less interdependent than the PBGs of conventional photonic crystals proposed before, affording interesting capabilities for us to tune the TM and TE PBGs separately. By altering the respective substructures, optical devices for different polarizations (TE, TM, or both) can readily be designed.

  3. Ultrawide-band photon routing based on chirped plasmonic gratings

    NASA Astrophysics Data System (ADS)

    Fu, Yulan; Hu, Xiaoyong; Yang, Hong; Gong, Qihuang

    2013-04-01

    We report an ultrawide-band photon routing based on a chirped plasmonic grating, which consists of a gold film coated with a chirped dielectric grating made of organic polymer poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]. The photon routing is realized based on rainbow-trapping like effect. An ultrawide operating bandwidth of 200 nm is reached through scanning near-field optical microscopy measurement. The tunable photon routing is reached through adjusting structural parameters of chirped plasmonic grating or using a pump light. A shift of 0.5 μm in the terminal channel is achieved for the 850-nm incident laser when the groove width changes from 150 to 180 nm.

  4. Absolutely calibrated CCD images of Saturn at methane band and continuum wavelengths during its 1991 opposition

    NASA Astrophysics Data System (ADS)

    Ortiz, J. L.; Moreno, F.; Molina, A.

    1993-02-01

    Ground-based charge-coupled device images of Saturn were obtained at the Cassegrain focus of the 1.52-m telescope at the Calar Alto Observatory (Andalucia, Spain) during the 1991 opposition. The images were obtained in and out of the absorption methane bands at 6190, 7250, and 8900A under very good seeing conditions. A Bayesian deconvolution technique was employed in the restoration procedure. The derived absolute reflectivities and band depths at some locations of the disk are provided in tables appropriate for analysis in terms of scattering models. Possible temporal variations between the reflectivities found here and those reported by West et al. (1982) are discussed. No longitudinal variations in reflectivity larger than a 4 percent level were found. Some images showed bright spot activity at the equatorial region.

  5. Hollow-Core Photonic Band Gap Fibers for Particle Acceleration

    SciTech Connect

    Noble, Robert J.; Spencer, James E.; Kuhlmey, Boris T.; /Sydney U.

    2011-08-19

    Photonic band gap (PBG) dielectric fibers with hollow cores are being studied both theoretically and experimentally for use as laser driven accelerator structures. The hollow core functions as both a longitudinal waveguide for the transverse-magnetic (TM) accelerating fields and a channel for the charged particles. The dielectric surrounding the core is permeated by a periodic array of smaller holes to confine the mode, forming a photonic crystal fiber in which modes exist in frequency pass-bands, separated by band gaps. The hollow core acts as a defect which breaks the crystal symmetry, and so-called defect, or trapped modes having frequencies in the band gap will only propagate near the defect. We describe the design of 2-D hollow-core PBG fibers to support TM defect modes with high longitudinal fields and high characteristic impedance. Using as-built dimensions of industrially-made fibers, we perform a simulation analysis of the first prototype PBG fibers specifically designed to support speed-of-light TM modes.

  6. Photonic band gaps in one-dimensional magnetized plasma photonic crystals with arbitrary magnetic declination

    SciTech Connect

    Zhang Haifeng; Liu Shaobin; Kong Xiangkun

    2012-12-15

    In this paper, the properties of photonic band gaps and dispersion relations of one-dimensional magnetized plasma photonic crystals composed of dielectric and magnetized plasma layers with arbitrary magnetic declination are theoretically investigated for TM polarized wave based on transfer matrix method. As TM wave propagates in one-dimensional magnetized plasma photonic crystals, the electromagnetic wave can be divided into two modes due to the influence of Lorentz force. The equations for effective dielectric functions of such two modes are theoretically deduced, and the transfer matrix equation and dispersion relations for TM wave are calculated. The influences of relative dielectric constant, plasma collision frequency, incidence angle, plasma filling factor, the angle between external magnetic field and +z axis, external magnetic field and plasma frequency on transmission, and dispersion relation are investigated, respectively, and some corresponding physical explanations are also given. From the numerical results, it has been shown that plasma collision frequency cannot change the locations of photonic band gaps for both modes, and also does not affect the reflection and transmission magnitudes. The characteristics of photonic band gaps for both modes can be obviously tuned by relative dielectric constant, incidence angle, plasma filling factor, the angle between external magnetic field and +z axis, external magnetic field and plasma frequency, respectively. These results would provide theoretical instructions for designing filters, microcavities, and fibers, etc.

  7. Band-dropping via coupled photonic crystal waveguides

    NASA Astrophysics Data System (ADS)

    Bayindir, Mehmet; Ozbay, Ekmel

    2002-11-01

    We observe the dropping of electromagnetic waves having a specific frequency or a certain frequency band in two-dimensional dielectric photonic crystals. The single frequency is dropped via cavity waveguide coupling. Tunability of the demultiplexing mode can be achieved by modifying the cavity properties. The band-dropping phenomenon is achieved by introducing interaction between an input planar, or coupled-cavity, waveguide and the output coupled-cavity waveguides (CCWs). The dropping band can be tuned by changing the coupling strength between the localized cavity modes of the output CCWs. We also calculate the transmission spectra and the field patterns by using the finite-difference-time-domain (FDTD)method. Calculated results agree well with the microwave measurements.

  8. Broadening of effective photonic band gaps in biological chiral structures: From intrinsic narrow band gaps to broad band reflection spectra

    NASA Astrophysics Data System (ADS)

    Vargas, W. E.; Hernández-Jiménez, M.; Libby, E.; Azofeifa, D. E.; Solis, Á.; Barboza-Aguilar, C.

    2015-09-01

    Under normal illumination with non-polarized light, reflection spectra of the cuticle of golden-like and red Chrysina aurigans scarabs show a structured broad band of left-handed circularly polarized light. The polarization of the reflected light is attributed to a Bouligand-type left-handed chiral structure found through the scarab's cuticle. By considering these twisted structures as one-dimensional photonic crystals, a novel approach is developed from the dispersion relation of circularly polarized electromagnetic waves traveling through chiral media, to show how the broad band characterizing these spectra arises from an intrinsic narrow photonic band gap whose spectral position moves through visible and near-infrared wavelengths.

  9. Two-Photon Lifetime Imaging of Voltage Indicating Proteins as a Probe of Absolute Membrane Voltage.

    PubMed

    Brinks, Daan; Klein, Aaron J; Cohen, Adam E

    2015-09-01

    Genetically encoded voltage indicators (GEVIs) can report cellular electrophysiology with high resolution in space and time. Two-photon (2P) fluorescence has been explored as a means to image voltage in tissue. Here, we used the 2P electronic excited-state lifetime to probe absolute membrane voltage in a manner that is insensitive to the protein expression level, illumination intensity, or photon detection efficiency. First, we tested several GEVIs for 2P brightness, response speed, and voltage sensitivity. ASAP1 and a previously described citrine-Arch electrochromic Förster resonance energy transfer sensor (dubbed CAESR) showed the best characteristics. We then characterized the voltage-dependent lifetime of ASAP1, CAESR, and ArcLight under voltage-clamp conditions. ASAP1 and CAESR showed voltage-dependent lifetimes, whereas ArcLight did not. These results establish 2P fluorescence lifetime imaging as a viable means of measuring absolute membrane voltage. We discuss the prospects and improvements necessary for applications in tissue.

  10. Two-Photon Lifetime Imaging of Voltage Indicating Proteins as a Probe of Absolute Membrane Voltage.

    PubMed

    Brinks, Daan; Klein, Aaron J; Cohen, Adam E

    2015-09-01

    Genetically encoded voltage indicators (GEVIs) can report cellular electrophysiology with high resolution in space and time. Two-photon (2P) fluorescence has been explored as a means to image voltage in tissue. Here, we used the 2P electronic excited-state lifetime to probe absolute membrane voltage in a manner that is insensitive to the protein expression level, illumination intensity, or photon detection efficiency. First, we tested several GEVIs for 2P brightness, response speed, and voltage sensitivity. ASAP1 and a previously described citrine-Arch electrochromic Förster resonance energy transfer sensor (dubbed CAESR) showed the best characteristics. We then characterized the voltage-dependent lifetime of ASAP1, CAESR, and ArcLight under voltage-clamp conditions. ASAP1 and CAESR showed voltage-dependent lifetimes, whereas ArcLight did not. These results establish 2P fluorescence lifetime imaging as a viable means of measuring absolute membrane voltage. We discuss the prospects and improvements necessary for applications in tissue. PMID:26331249

  11. Unfolding the band structure of non-crystalline photonic band gap materials

    PubMed Central

    Tsitrin, Samuel; Williamson, Eric Paul; Amoah, Timothy; Nahal, Geev; Chan, Ho Leung; Florescu, Marian; Man, Weining

    2015-01-01

    Non-crystalline photonic band gap (PBG) materials have received increasing attention, and sizeable PBGs have been reported in quasi-crystalline structures and, more recently, in disordered structures. Band structure calculations for periodic structures produce accurate dispersion relations, which determine group velocities, dispersion, density of states and iso-frequency surfaces, and are used to predict a wide-range of optical phenomena including light propagation, excited-state decay rates, temporal broadening or compression of ultrashort pulses and complex refraction phenomena. However, band calculations for non-periodic structures employ large super-cells of hundreds to thousands building blocks, and provide little useful information other than the PBG central frequency and width. Using stereolithography, we construct cm-scale disordered PBG materials and perform microwave transmission measurements, as well as finite-difference time-domain (FDTD) simulations. The photonic dispersion relations are reconstructed from the measured and simulated phase data. Our results demonstrate the existence of sizeable PBGs in these disordered structures and provide detailed information of the effective band diagrams, dispersion relation, iso-frequency contours, and their angular dependence. Slow light phenomena are also observed in these structures near gap frequencies. This study introduces a powerful tool to investigate photonic properties of non-crystalline structures and provides important effective dispersion information, otherwise difficult to obtain. PMID:26289434

  12. Introducing Defects in Photonic Band-Gap (PBG) Crystals

    SciTech Connect

    Johnson, Elliott C.; /North Dakota State U. /SLAC

    2007-11-07

    Photonic Band-Gap (PBG) fibers are a periodic array of optical materials arranged in a lattice called a photonic crystal. The use of PBG fibers for particle acceleration is being studied by the Advanced Accelerator Research Department (AARD) at SLAC. By introducing defects in such fibers, e.g. removing one or more capillaries from a hexagonal lattice, spatially confined modes suitable for particle acceleration may be created. The AARD has acquired several test samples of PBG fiber arrays with varying refractive index, capillary size, and length from an external vendor for testing. The PBGs were inspected with a microscope and characteristics of the capillaries including radii, spacing, and errors in construction were determined. Transmission tests were performed on these samples using a broad-range spectrophotometer. In addition, detailed E-field simulations of different PBG configurations were done using the CUDOS and RSOFT codes. Several accelerating modes for different configurations were found and studied in detail.

  13. Photonic crystals composed of virtual pillars with magnetic walls: Photonic band gaps and double Dirac cones

    NASA Astrophysics Data System (ADS)

    Kim, Seong-Han; Kim, Soeun; Kee, Chul-Sik

    2016-08-01

    Photonic crystals composed of virtual pillars with magnetic walls are proposed. A virtual pillar with a magnetic wall can be created inside a parallel perfect electric conductor plate waveguide by introducing a circular perfect magnetic conductor patch in the upper perfect electric conductor plate of the waveguide. The virtual pillar mimics a perfect magnetic conductor pillar with a radius less than that of the circular patch because electromagnetic waves can slightly penetrate the wall. Furthermore, the photonic band structures of a triangular photonic crystal composed of virtual pillars for the transverse electromagnetic modes of the waveguide are investigated. They are very similar to those of a triangular photonic crystal composed of infinitely long perfect electric conductor cylinders for transverse magnetic modes. The similarity between the two different photonic crystals is well understood by the boundary conditions of perfect electric and magnetic conductor surfaces. A double Dirac cone at the center of the Brillouin zone is observed and thus the virtual pillar triangular photonic crystal can act a zero-refractive-index material at the Dirac point frequency.

  14. Enhanced two-photon absorption in a hollow-core photonic-band-gap fiber

    SciTech Connect

    Saha, Kasturi; Venkataraman, Vivek; Londero, Pablo; Gaeta, Alexander L.

    2011-03-15

    We show that two-photon absorption (TPA) in rubidium atoms can be greatly enhanced by the use of a hollow-core photonic-band-gap fiber. We investigate off-resonant, degenerate Doppler-free TPA on the 5S{sub 1/2{yields}}5D{sub 5/2} transition and observe 1% absorption of a pump beam with a total power of only 1 mW in the fiber. These results are verified by measuring the amount of emitted blue fluorescence and are consistent with the theoretical predictions which indicate that transit-time effects play an important role in determining the two-photon absorption cross section in a confined geometry.

  15. Correlation of symptom clusters of schizophrenia with absolute powers of main frequency bands in quantitative EEG

    PubMed Central

    Gross, Andres; Joutsiniemi, Sirkka-Liisa; Rimon, Ranan; Appelberg, Björn

    2006-01-01

    Background Research of QEEG activity power spectra has shown intriguing results in patients with schizophrenia. Different symptom clusters have been correlated to QEEG frequency bands. The findings have been to some extent inconsistent. Replication of the findings of previous research is thus an important task. In the current study we investigated the correlations between the absolute powers of delta, theta, alpha, and beta frequency bands over the fronto-central scalp area (FC) with the PANSS subscales and the Liddle's factors in 16 patients with schizophrenia. The authors hypothesised a priori the correlations reported by Harris et al (1999) of PANSS negative subscale with delta power, Liddle's psychomotor poverty with delta and beta powers, disorganisation with delta power and reality distortion with alpha power on the midline FC. Methods The sample consisted of 16 patients with chronic schizophrenia considered as having insufficient clinical response to conventional antipsychotic treatment and evidencing a relapse. The correlations between quantitative electroencephalography (QEEG) absolute powers of delta (1.5–3.0 Hz), theta (3.0–7.5 Hz), alpha (7.5–12.5 Hz), and beta (12.5–20.0 Hz) frequency bands over the fronto-central scalp area (FC) with PANSS subscales and Liddle's factors (reality distortion, disorganisation, psychomotor poverty) were investigated. Results Significant positive correlations were found between the beta and psychomotor poverty (p < 0.05). Trends towards positive correlations (p < 0.1) were observed between delta and PANSS negative subscale and psychomotor poverty. Alpha did not correlate with reality distortion and delta did not correlate with disorganisation. Post hoc analysis revealed correlations of the same magnitude between beta and psychopathology generally over FC. Conclusion The a priori hypothesis was partly supported by the correlation of the beta and psychomotor poverty. Liddle's factors showed correlations of the same

  16. Using DNA origami nanostructures to determine absolute cross sections for UV photon-induced DNA strand breakage.

    PubMed

    Vogel, Stefanie; Rackwitz, Jenny; Schürman, Robin; Prinz, Julia; Milosavljević, Aleksandar R; Réfrégiers, Matthieu; Giuliani, Alexandre; Bald, Ilko

    2015-11-19

    We have characterized ultraviolet (UV) photon-induced DNA strand break processes by determination of absolute cross sections for photoabsorption and for sequence-specific DNA single strand breakage induced by photons in an energy range from 6.50 to 8.94 eV. These represent the lowest-energy photons able to induce DNA strand breaks. Oligonucleotide targets are immobilized on a UV transparent substrate in controlled quantities through attachment to DNA origami templates. Photon-induced dissociation of single DNA strands is visualized and quantified using atomic force microscopy. The obtained quantum yields for strand breakage vary between 0.06 and 0.5, indicating highly efficient DNA strand breakage by UV photons, which is clearly dependent on the photon energy. Above the ionization threshold strand breakage becomes clearly the dominant form of DNA radiation damage, which is then also dependent on the nucleotide sequence.

  17. Wide-Band Microwave Receivers Using Photonic Processing

    NASA Technical Reports Server (NTRS)

    Matsko, Andrey; Maleki, Lute; Itchenko, Vladimir; Yu, Nan; Strekalov, Dmitry; Savchenkov, Anatoliy

    2008-01-01

    In wide-band microwave receivers of a type now undergoing development, the incoming microwave signals are electronically preamplified, then frequency-up-converted to optical signals that are processed photonically before being detected. This approach differs from the traditional approach, in which incoming microwave signals are processed by purely electronic means. As used here, wide-band microwave receivers refers especially to receivers capable of reception at any frequency throughout the range from about 90 to about 300 GHz. The advantage expected to be gained by following the up-conversion-and-photonic-processing approach is the ability to overcome the limitations of currently available detectors and tunable local oscillators in the frequency range of interest. In a receiver following this approach (see figure), a preamplified incoming microwave signal is up-converted by the method described in the preceeding article. The frequency up-converter exploits the nonlinearity of the electromagnetic response of a whispering gallery mode (WGM) resonator made of LiNbO3. Up-conversion takes place by three-wave mixing in the resonator. The WGM resonator is designed and fabricated to function simultaneously as an electro-optical modulator and to exhibit resonance at the microwave and optical operating frequencies plus phase matching among the microwave and optical signals circulating in the resonator. The up-conversion is an efficient process, and the efficiency is enhanced by the combination of microwave and optical resonances. The up-converted signal is processed photonically by use of a tunable optical filter or local oscillator, and is then detected. Tunable optical filters can be made to be frequency agile and to exhibit high resonance quality factors (high Q values), thereby making it possible to utilize a variety of signal-processing modalities. Therefore, it is anticipated that when fully developed, receivers of this type will be compact and will be capable of both

  18. Observation of localized flat-band modes in a quasi-one-dimensional photonic rhombic lattice.

    PubMed

    Mukherjee, Sebabrata; Thomson, Robert R

    2015-12-01

    We experimentally demonstrate the photonic realization of a dispersionless flat band in a quasi-one-dimensional photonic lattice fabricated by ultrafast laser inscription. In the nearest neighbor tight binding approximation, the lattice supports two dispersive and one nondispersive (flat) band. We experimentally excite superpositions of flat-band eigenmodes at the input of the photonic lattice and show the diffractionless propagation of the input states due to their infinite effective mass. In the future, the use of photonic rhombic lattices, together with the successful implementation of a synthetic gauge field, will enable the observation of Aharonov-Bohm photonic caging.

  19. Effect of implementation of a Bragg reflector in the photonic band structure of the Suzuki-phase photonic crystal lattice.

    PubMed

    Martinez, Luis Javier; Alija, Alfonso Rodriguez; Postigo, Pablo Aitor; Galisteo-López, J F; Galli, Matteo; Andreani, Lucio Claudio; Seassal, Christian; Viktorovitch, Pierre

    2008-06-01

    We investigate the change of the photonic band structure of the Suzuki-phase photonic crystal lattice when the horizontal mirror symmetry is broken by an underlying Bragg reflector. The structure consists of an InP photonic crystal slab including four InAsP quantum wells, a SiO(2) bonding layer, and a bottom high index contrast Si/SiO(2) Bragg mirror deposited on a Si wafer. Angle- and polarization-resolved photoluminescence spectroscopy has been used for measuring the photonic band structure and for investigating the coupling to a polarized plane wave in the far field. A drastic change in the k-space photonic dispersion between the structure with and without Bragg reflector is measured. An important enhancement on the photoluminescence emission up to seven times has been obtained for a nearly flat photonic band, which is characteristic of the Suzuki-phase lattice.

  20. Tunable complete photonic band gap in anisotropic photonic crystal slabs with non-circular air holes using liquid crystals

    NASA Astrophysics Data System (ADS)

    Fathollahi Khalkhali, T.; Bananej, A.

    2016-06-01

    In this study, we analyze the tunability of complete photonic band gap of square and triangular photonic crystal slabs composed of square and hexagonal air holes in anisotropic tellurium background with SiO2 as cladding material. The non-circular holes are infiltrated with liquid crystal. Using the supercell method based on plane wave expansion, we study the variation of complete band gap by changing the optical axis orientation of liquid crystal. Our numerical results show that noticeable tunability of complete photonic band gap can be obtained in both square and triangular structures with non-circular holes.

  1. Tunable photonic band-gaps in one-dimensional photonic crystals containing linear graded index material

    NASA Astrophysics Data System (ADS)

    Singh, Bipin K.; Kumar, Pawan; Pandey, Praveen C.

    2014-12-01

    We have demonstrated control of the photonic band gaps (PBGs) in 1-D photonic crystals using linear graded index material. The analysis of PBG has been done in THz region by considering photonic crystals in the form of ten periods of second, third and fourth generation of the Fibonacci sequence as unit cell. The unit cells are constituted of two kinds of layers; one is taken of linear graded index material and other of normal dielectric material. For this investigation, we used a theoretical model based on transfer matrix method. We have obtained a large number of PBGs and their bandwidths can be tuned by changing the grading profile and thicknesses of linear graded index layers. The number of PBGs increases with increase in the thicknesses of layers and their bandwidths can be controlled by the contrast of initial and final refractive index of the graded layers. In this way, we provide more design freedom for photonic devices such as reflectors, filters, optical sensors, couplers, etc.

  2. The Photonic Band Gaps in the Two-Dimensional Plasma Photonic Crystals with Rhombus Lattice

    NASA Astrophysics Data System (ADS)

    Zhang, Kaiming; Sun, Dongsheng

    2016-06-01

    In this paper, under two different electromagnetic modes, the photonic band gaps (PBGs) in the two-dimensional plasma photonic crystals (PPCs) are theoretically investigated based on the plane wave expansion method. The proposed PPCs are arranged in rhombus lattices, in which the homogeneous unmagnetized plasma rods are immersed in the isotropic dielectric background. The computed results showed that PBGs can be easily tuned by the angle of rhombus lattices, and a cutoff frequency and a flatbands region can be observed under the TM and TE polarized waves, respectively. The relationships between the relative bandwidths of first PBGs and the parameters of PPCs in two such cases also are discussed. The numerical simulations showed that the PBGs can be manipulated obviously by the parameters as mentioned above. The proposed results can be used to design the waveguide and filter based on the PPCs.

  3. Absolute integrated intensity and individual line parameters for the 6.2-micron band of NO2. [in solar spectrum

    NASA Technical Reports Server (NTRS)

    Goldman, A.; Bonomo, F. S.; Williams, W. J.; Murcray, D. G.; Snider, D. E.

    1975-01-01

    The absolute integrated intensity of the 6.2-micron band of NO2 at 40 C was determined from quantitative spectra at about 10 per cm resolution by the spectral band model technique. A value of 1430 plus or minus 300 per sq cm per atm was obtained. Individual line parameters, positions, intensities, and ground-state energies were derived, and line-by-line calculations were compared with the band model results and with the quantitative spectra obtained at about 0.5 per cm resolution.

  4. Photonic band gaps of wurtzite GaN and AlN photonic crystals at short wavelengths

    NASA Astrophysics Data System (ADS)

    Melo, E. G.; Alayo, M. I.

    2015-04-01

    Group III-nitride materials such as GaN and AlN have attracted a great attention in researches on photonic devices that operate at short light wavelengths. The large band gaps of these materials turn them suitable for nanophotonic devices that operate in light ranges from visible to deep ultraviolet. The physical properties of wurtzite GaN and AlN such as their second and third order nonlinear susceptibilities, and their thermal and piezoelectric coefficients, also make them excellent candidates for integrate photonic devices with electronics, microelectromechanics, microfluidics and general sensing applications. Using a plane wave expansion method (PWE) the photonic band gap maps of 36 different two-dimensional photonic crystal lattices in wurtzite GaN and AlN were obtained and analyzed. The wavelength dependence and the effects of the material anisotropy on the position of the photonic band gaps are also discussed. The results show regions with slow group velocity at the edges of a complete photonic band gap in the M-K direction of the triangular lattices with circular, hexagonal, and rhombic air holes. Was also found a very interesting disposition of the photonic band gaps in the lattices composed of rhombic air holes.

  5. Geometric phase and entanglement of Raman photon pairs in the presence of photonic band gap

    SciTech Connect

    Berrada, K.; Ooi, C. H. Raymond; Abdel-Khalek, S.

    2015-03-28

    Robustness of the geometric phase (GP) with respect to different noise effects is a basic condition for an effective quantum computation. Here, we propose a useful quantum system with real physical parameters by studying the GP of a pair of Stokes and anti-Stokes photons, involving Raman emission processes with and without photonic band gap (PBG) effect. We show that the properties of GP are very sensitive to the change of the Rabi frequency and time, exhibiting collapse phenomenon as the time becomes significantly large. The system allows us to obtain a state which remains with zero GP for longer times. This result plays a significant role to enhance the stabilization and control of the system dynamics. Finally, we investigate the nonlocal correlation (entanglement) between the pair photons by taking into account the effect of different parameters. An interesting correlation between the GP and entanglement is observed showing that the PBG stabilizes the fluctuations in the system and makes the entanglement more robust against the change of time and frequency.

  6. Hypersonic modulation of light in three-dimensional photonic and phononic band-gap materials.

    PubMed

    Akimov, A V; Tanaka, Y; Pevtsov, A B; Kaplan, S F; Golubev, V G; Tamura, S; Yakovlev, D R; Bayer, M

    2008-07-18

    The elastic coupling between the a-SiO2 spheres composing opal films brings forth three-dimensional periodic structures which besides a photonic stop band are predicted to also exhibit complete phononic band gaps. The influence of elastic crystal vibrations on the photonic band structure has been studied by injection of coherent hypersonic wave packets generated in a metal transducer by subpicosecond laser pulses. These studies show that light with energies close to the photonic band gap can be efficiently modulated by hypersonic waves.

  7. Communication: excitation band modulation with high-order photonic band gap in PMMA:Eu(TTA)3(TPPO)2 opals.

    PubMed

    Xu, Wen; Bai, Xue; Zhu, Yongsheng; Liu, Tong; Xu, Sai; Dong, Biao; Song, Hongwei

    2013-05-14

    Changes in the excitation spectra of luminescent species inserted in photorefractive crystals as a function of changes in the high-order photonic band gap (PBG) have not been previously observed. In this communication, we present our results monitoring the excitation band of Eu(TTA)3(TPPO)2 inserted in the PMMA opal photonic crystals as a function of the changes in the high-order PBG of the crystals. We find shifts in the complex excitation band and changes in the integrated emission intensity that correlates with shifts in the high-order PBG through coupling to the excitation transition. PMID:23676019

  8. Communication: Excitation band modulation with high-order photonic band gap in PMMA:Eu(TTA)3(TPPO)2 opals

    NASA Astrophysics Data System (ADS)

    Xu, Wen; Bai, Xue; Zhu, Yongsheng; Liu, Tong; Xu, Sai; Dong, Biao; Song, Hongwei

    2013-05-01

    Changes in the excitation spectra of luminescent species inserted in photorefractive crystals as a function of changes in the high-order photonic band gap (PBG) have not been previously observed. In this communication, we present our results monitoring the excitation band of Eu(TTA)3(TPPO)2 inserted in the PMMA opal photonic crystals as a function of the changes in the high-order PBG of the crystals. We find shifts in the complex excitation band and changes in the integrated emission intensity that correlates with shifts in the high-order PBG through coupling to the excitation transition.

  9. Communication: excitation band modulation with high-order photonic band gap in PMMA:Eu(TTA)3(TPPO)2 opals.

    PubMed

    Xu, Wen; Bai, Xue; Zhu, Yongsheng; Liu, Tong; Xu, Sai; Dong, Biao; Song, Hongwei

    2013-05-14

    Changes in the excitation spectra of luminescent species inserted in photorefractive crystals as a function of changes in the high-order photonic band gap (PBG) have not been previously observed. In this communication, we present our results monitoring the excitation band of Eu(TTA)3(TPPO)2 inserted in the PMMA opal photonic crystals as a function of the changes in the high-order PBG of the crystals. We find shifts in the complex excitation band and changes in the integrated emission intensity that correlates with shifts in the high-order PBG through coupling to the excitation transition.

  10. Photonic bands in two-dimensional microplasma arrays. I. Theoretical derivation of band structures of electromagnetic waves

    SciTech Connect

    Sakai, Osamu; Sakaguchi, Takui; Tachibana, Kunihide

    2007-04-01

    Two theoretical approaches appropriate for two-dimensional plasma photonic crystals reveal dispersions of propagating waves including photonic (electromagnetic) band gaps and multiflatbands. A modified plane-wave expansion method yields dispersions of collisional periodical plasmas, and the complex-value solution of a wave equation by a finite difference method enables us to obtain dispersions with structure effects in an individual microplasma. Periodical plasma arrays form band gaps as well as normal photonic crystals, and multiflatbands are present below the electron plasma frequency in the transverse electric field mode. Electron elastic collisions lower the top frequency of the multiflatbands but have little effect on band gap properties. The spatial gradient of the local dielectric constant resulting from an electron density profile widens the frequency region of the multiflatbands, as demonstrated by the change of surface wave distributions. Propagation properties described in dispersions including band gaps and flatbands agree with experimental observations of microplasma arrays.

  11. Photonic-Band-Gap Traveling-Wave Gyrotron Amplifier

    PubMed Central

    Nanni, E. A.; Lewis, S. M.; Shapiro, M. A.; Griffin, R. G.; Temkin, R. J.

    2014-01-01

    We report the experimental demonstration of a gyrotron traveling-wave-tube amplifier at 250 GHz that uses a photonic band gap (PBG) interaction circuit. The gyrotron amplifier achieved a peak small signal gain of 38 dB and 45 W output power at 247.7 GHz with an instantaneous −3 dB bandwidth of 0.4 GHz. The amplifier can be tuned for operation from 245–256 GHz. The widest instantaneous −3 dB bandwidth of 4.5 GHz centered at 253.25 GHz was observed with a gain of 24 dB. The PBG circuit provides stability from oscillations by supporting the propagation of transverse electric (TE) modes in a narrow range of frequencies, allowing for the confinement of the operating TE03-like mode while rejecting the excitation of oscillations at nearby frequencies. This experiment achieved the highest frequency of operation for a gyrotron amplifier; at present, there are no other amplifiers in this frequency range that are capable of producing either high gain or high output power. This result represents the highest gain observed above 94 GHz and the highest output power achieved above 140 GHz by any conventional-voltage vacuum electron device based amplifier. PMID:24476286

  12. Absolute intensity measurements of the CO2 bands 401-III /backward arrow/ 000 and 411-III /backward arrow/ 010

    NASA Technical Reports Server (NTRS)

    Valero, F. P. J.

    1977-01-01

    The absolute intensities of the studied transitions of CO2 have been measured from spectra obtained under high resolution. Vibration-rotation line intensities and integrated band intensities are reported. The studied bands are characterized by origins at 7593.5 and 7584 cm to the minus 1. Spectra were obtained by an Ames' 25-m base path White-type absorption cell equipped with silver-coated mirrors together with a 5-m focal length Czerny-Turner scanning spectrometer. The procedures for calculating the widths and intensities are explained, and uncertainty limits of the reported values are considered.

  13. Observation of a Localized Flat-Band State in a Photonic Lieb Lattice.

    PubMed

    Mukherjee, Sebabrata; Spracklen, Alexander; Choudhury, Debaditya; Goldman, Nathan; Öhberg, Patrik; Andersson, Erika; Thomson, Robert R

    2015-06-19

    We demonstrate the first experimental realization of a dispersionless state, in a photonic Lieb lattice formed by an array of optical waveguides. This engineered lattice supports three energy bands, including a perfectly flat middle band with an infinite effective mass. We analyze, both experimentally and theoretically, the evolution of well-prepared flat-band states, and show their remarkable robustness, even in the presence of disorder. The realization of flat-band states in photonic lattices opens an exciting door towards quantum simulation of flat-band models in a highly controllable environment.

  14. Observation of localized flat-band states in Kagome photonic lattices.

    PubMed

    Zong, Yuanyuan; Xia, Shiqiang; Tang, Liqin; Song, Daohong; Hu, Yi; Pei, Yumiao; Su, Jing; Li, Yigang; Chen, Zhigang

    2016-04-18

    We report the first experimental demonstration of localized flat-band states in optically induced Kagome photonic lattices. Such lattices exhibit a unique band structure with the lowest band being completely flat (diffractionless) in the tight-binding approximation. By taking the advantage of linear superposition of the flat-band eigenmodes of the Kagome lattices, we demonstrate a high-fidelity transmission of complex patterns in such two-dimensional pyrochlore-like photonic structures. Our numerical simulations find good agreement with experimental observations, upholding the belief that flat-band lattices can support distortion-free image transmission.

  15. High-Power Fiber Lasers Using Photonic Band Gap Materials

    NASA Technical Reports Server (NTRS)

    DiDomenico, Leo; Dowling, Jonathan

    2005-01-01

    High-power fiber lasers (HPFLs) would be made from photonic band gap (PBG) materials, according to the proposal. Such lasers would be scalable in the sense that a large number of fiber lasers could be arranged in an array or bundle and then operated in phase-locked condition to generate a superposition and highly directed high-power laser beam. It has been estimated that an average power level as high as 1,000 W per fiber could be achieved in such an array. Examples of potential applications for the proposed single-fiber lasers include welding and laser surgery. Additionally, the bundled fibers have applications in beaming power through free space for autonomous vehicles, laser weapons, free-space communications, and inducing photochemical reactions in large-scale industrial processes. The proposal has been inspired in part by recent improvements in the capabilities of single-mode fiber amplifiers and lasers to produce continuous high-power radiation. In particular, it has been found that the average output power of a single strand of a fiber laser can be increased by suitably changing the doping profile of active ions in its gain medium to optimize the spatial overlap of the electromagnetic field with the distribution of active ions. Such optimization minimizes pump power losses and increases the gain in the fiber laser system. The proposal would expand the basic concept of this type of optimization to incorporate exploitation of the properties (including, in some cases, nonlinearities) of PBG materials to obtain power levels and efficiencies higher than are now possible. Another element of the proposal is to enable pumping by concentrated sunlight. Somewhat more specifically, the proposal calls for exploitation of the properties of PBG materials to overcome a number of stubborn adverse phenomena that have impeded prior efforts to perfect HPFLs. The most relevant of those phenomena is amplified spontaneous emission (ASE), which causes saturation of gain and power

  16. Photonic band gap of three dimensional magnetized photonic crystal with Voigt configuration

    NASA Astrophysics Data System (ADS)

    Zhang, Hai-Feng; Liu, Shao-Bin; Kong, Xiang-Kun; Li, Bing-Xiang

    2013-08-01

    In this paper, the properties of two types of three-dimensional magnetized plasma photonic crystals (MPPCs) composed of homogeneous magnetized plasma and dielectric with simple-cubic lattices are theoretically studied by a modified plane wave expansion (PWE) method, as the magneto-optical Voigt effects of magnetized plasma are considered. The equations for type-1 structures with simple-cubic lattices (dielectric spheres immersed in magnetized plasma background), are theoretically deduced. The influences of dielectric constant of dielectric, plasma collision frequency, filling factor, the external magnetic field and plasma frequency on the properties of photonic band gaps (PBGs) for both types of MPPCs are investigated in detail, respectively, and some corresponding physical explanations are also given. The characteristics of flatbands regions are also discussed. From the numerical results, it has been shown that the PBGs of both types of three-dimensional MPPCs can be manipulated by plasma frequency, filling factor, the external magnetic field and the relative dielectric constant of dielectric, respectively. However, the plasma collision frequency has no effects on the PBGs for two types of three-dimensional MPPCs. The locations of flatbands regions can not be tuned by any parameters except for plasma frequency and the external magnetic field.

  17. A rare gas optics-free absolute photon flux and energy analyzer to provide absolute photoionization rates of inflowing interstellar neutrals

    NASA Technical Reports Server (NTRS)

    Judge, Darrell L.

    1994-01-01

    A prototype spectrometer has been developed for space applications requiring long term absolute EUV photon flux measurements. The energy spectrum of the incoming photons is transformed directly into an electron energy spectrum by taking advantage of the photoelectric effect in one of several rare gases at low pressures. Using an electron energy spectrometer, followed by an electron multiplier detector, pulses due to individual electrons are counted. The overall efficiency of this process can be made essentially independent of gain drifts in the signal path, and the secular degradation of optical components which is often a problem in other techniques is avoided. A very important feature of this approach is its freedom from the problem of overlapping spectral orders that plagues grating EUV spectrometers. An instrument with these features has not been flown before, but is essential to further advances in our understanding of solar EUV flux dynamics, and the coupled dynamics of terrestrial and planetary atmospheres. The detailed characteristics of this optics-free spectrometer are presented in the publications section.

  18. X-Band Photonic Band-Gap Accelerator Structure Breakdown Experiment

    SciTech Connect

    Marsh, Roark A.; Shapiro, Michael A.; Temkin, Richard J.; Dolgashev, Valery A.; Laurent, Lisa L.; Lewandowski, James R.; Yeremian, A.Dian; Tantawi, Sami G.; /SLAC

    2012-06-11

    In order to understand the performance of photonic band-gap (PBG) structures under realistic high gradient, high power, high repetition rate operation, a PBG accelerator structure was designed and tested at X band (11.424 GHz). The structure consisted of a single test cell with matching cells before and after the structure. The design followed principles previously established in testing a series of conventional pillbox structures. The PBG structure was tested at an accelerating gradient of 65 MV/m yielding a breakdown rate of two breakdowns per hour at 60 Hz. An accelerating gradient above 110 MV/m was demonstrated at a higher breakdown rate. Significant pulsed heating occurred on the surface of the inner rods of the PBG structure, with a temperature rise of 85 K estimated when operating in 100 ns pulses at a gradient of 100 MV/m and a surface magnetic field of 890 kA/m. A temperature rise of up to 250 K was estimated for some shots. The iris surfaces, the location of peak electric field, surprisingly had no damage, but the inner rods, the location of the peak magnetic fields and a large temperature rise, had significant damage. Breakdown in accelerator structures is generally understood in terms of electric field effects. These PBG structure results highlight the unexpected role of magnetic fields in breakdown. The hypothesis is presented that the moderate level electric field on the inner rods, about 14 MV/m, is enhanced at small tips and projections caused by pulsed heating, leading to breakdown. Future PBG structures should be built to minimize pulsed surface heating and temperature rise.

  19. Triple photonic band-gap structure dynamically induced in the presence of spontaneously generated coherence

    SciTech Connect

    Gao Jinwei; Bao Qianqian; Wan Rengang; Cui Cuili; Wu Jinhui

    2011-05-15

    We study a cold atomic sample coherently driven into the five-level triple-{Lambda} configuration for attaining a dynamically controlled triple photonic band-gap structure. Our numerical calculations show that three photonic band gaps with homogeneous reflectivities up to 92% can be induced on demand around the probe resonance by a standing-wave driving field in the presence of spontaneously generated coherence. All these photonic band gaps are severely malformed with probe reflectivities declining rapidly to very low values when spontaneously generated coherence is gradually weakened. The triple photonic band-gap structure can also be attained in a five-level chain-{Lambda} system of cold atoms in the absence of spontaneously generated coherence, which however requires two additional traveling-wave fields to couple relevant levels.

  20. Fabrication of 3-D Photonic Band Gap Crystals Via Colloidal Self-Assembly

    NASA Technical Reports Server (NTRS)

    Subramaniam, Girija; Blank, Shannon

    2005-01-01

    The behavior of photons in a Photonic Crystals, PCs, is like that of electrons in a semiconductor in that, it prohibits light propagation over a band of frequencies, called Photonic Band Gap, PBG. Photons cannot exist in these band gaps like the forbidden bands of electrons. Thus, PCs lend themselves as potential candidates for devices based on the gap phenomenon. The popular research on PCs stem from their ability to confine light with minimal losses. Large scale 3-D PCs with a PBG in the visible or near infra red region will make optical transistors and sharp bent optical fibers. Efforts are directed to use PCs for information processing and it is not long before we can have optical integrated circuits in the place of electronic ones.

  1. Investigation on the properties of omnidirectional photonic band gaps in two-dimensional plasma photonic crystals

    NASA Astrophysics Data System (ADS)

    Zhang, Hai-Feng; Liu, Shao-Bin; Li, Bing-Xiang

    2016-01-01

    The properties of omnidirectional photonic band gaps (OBGs) in two-dimensional plasma photonic crystals (2D PPCs) are theoretically investigated by the modified plane wave expansion method. In the simulation, we consider the off-plane incident wave vector. The configuration of 2D PPCs is the triangular lattices filled with the nonmagnetized plasma cylinders in the homogeneous and isotropic dielectric background. The calculated results show that the proposed 2D PPCs possess a flatbands region and the OBGs. Compared with the OBGs in the conventional 2D dielectric-air PCs, it can be obtained more easily and enlarged in the 2D PPCs with a similar structure. The effects of configurational parameters of the PPCs on the OBGs also are studied. The simulated results demonstrate that the locations of OBGs can be tuned easily by manipulating those parameters except for changing plasma collision frequency. The achieved OBGs can be enlarged by optimizations. The OBGs of two novel configurations of PPCs with different cross sections are computed for a comparison. Both configurations have the advantages of obtaining the larger OBGs compared with the conventional configuration, since the symmetry of 2D PPCs is broken by different sizes of periodically inserted plasma cylinders or connected by the embedded plasma cylinders with thin veins. The analysis of the results shows that the bandwidths of OBGs can be tuned by changing geometric and physical parameters of such two PPCs structures. The theoretical results may open a new scope for designing the omnidirectional reflectors or mirrors based on the 2D PPCs.

  2. Field demonstration of X-band photonic antenna remoting in the Deep Space Network

    NASA Technical Reports Server (NTRS)

    Yao, X. S.; Lutes, G.; Logan, R. T., Jr.; Maleki, L.

    1994-01-01

    We designed a photonic link for antenna remoting based on our integrated system analysis. With this 12-km link, we successfully demonstrated photonic antenna-remoting capability at X-band (8.4 GHz) at one of NASA's Deep Space Stations while tracking the Magellan spacecraft.

  3. Finite element method analysis of band gap and transmission of two-dimensional metallic photonic crystals at terahertz frequencies.

    PubMed

    Degirmenci, Elif; Landais, Pascal

    2013-10-20

    Photonic band gap and transmission characteristics of 2D metallic photonic crystals at THz frequencies have been investigated using finite element method (FEM). Photonic crystals composed of metallic rods in air, in square and triangular lattice arrangements, are considered for transverse electric and transverse magnetic polarizations. The modes and band gap characteristics of metallic photonic crystal structure are investigated by solving the eigenvalue problem over a unit cell of the lattice using periodic boundary conditions. A photonic band gap diagram of dielectric photonic crystal in square lattice array is also considered and compared with well-known plane wave expansion results verifying our FEM approach. The photonic band gap designs for both dielectric and metallic photonic crystals are consistent with previous studies obtained by different methods. Perfect match is obtained between photonic band gap diagrams and transmission spectra of corresponding lattice structure. PMID:24216592

  4. Finite element method analysis of band gap and transmission of two-dimensional metallic photonic crystals at terahertz frequencies.

    PubMed

    Degirmenci, Elif; Landais, Pascal

    2013-10-20

    Photonic band gap and transmission characteristics of 2D metallic photonic crystals at THz frequencies have been investigated using finite element method (FEM). Photonic crystals composed of metallic rods in air, in square and triangular lattice arrangements, are considered for transverse electric and transverse magnetic polarizations. The modes and band gap characteristics of metallic photonic crystal structure are investigated by solving the eigenvalue problem over a unit cell of the lattice using periodic boundary conditions. A photonic band gap diagram of dielectric photonic crystal in square lattice array is also considered and compared with well-known plane wave expansion results verifying our FEM approach. The photonic band gap designs for both dielectric and metallic photonic crystals are consistent with previous studies obtained by different methods. Perfect match is obtained between photonic band gap diagrams and transmission spectra of corresponding lattice structure.

  5. Photonics aided ultra-wideband W-band signal generation and air space transmission

    NASA Astrophysics Data System (ADS)

    Li, Xinying; Yu, Jianjun

    2016-02-01

    We achieve several field trial demonstrations of ultra-wideband W-band millimeter-wave (mm-wave) signal generation and its long-distance air space transmission based on some enabling technologies and advanced devices. First, we demonstrated photonics generation and up to 1.7-km wireless delivery of 20-Gb/s polarization division multiplexing quadrature phase shift keying (PDM-QPSK) signal at W-band, adopting both optical and antenna polarization multiplexing. Then, we demonstrated photonics generation and up to 300-m wireless delivery of 80-Gb/s PDM-QPSK signal at W-band, adopting both optical and antenna polarization multiplexing as well as multi-band multiplexing. We also demonstrated photonics generation and up to 100-m wireless delivery of 100-Gb/s QPSK signal at W-band, adopting antenna polarization multiplexing.

  6. The ground-based H-, K-, and L-band absolute emission spectra of HD 209458b

    SciTech Connect

    Zellem, Robert T.; Griffith, Caitlin A.; Deroo, Pieter; Swain, Mark R.; Waldmann, Ingo P.

    2014-11-20

    Here we explore the capabilities of NASA's 3.0 m Infrared Telescope Facility (IRTF) and SpeX spectrometer and the 5.08 m Hale telescope with the TripleSpec spectrometer with near-infrared H-, K-, and L-band measurements of HD 209458b's secondary eclipse. Our IRTF/SpeX data are the first absolute L-band spectroscopic emission measurements of any exoplanet other than the hot Jupiter HD 189733b. Previous measurements of HD 189733b's L band indicate bright emission hypothesized to result from non-LTE CH{sub 4} ν{sub 3} fluorescence. We do not detect a similar bright 3.3 μm feature to ∼3σ, suggesting that fluorescence does not need to be invoked to explain HD 209458b's L-band measurements. The validity of our observation and reduction techniques, which decrease the flux variance by up to 2.8 orders of magnitude, is reinforced by 1σ agreement with existent Hubble/NICMOS and Spitzer/IRAC1 observations that overlap the H, K, and L bands, suggesting that both IRTF/SpeX and Palomar/TripleSpec can measure an exoplanet's emission with high precision.

  7. Crystalline sulfur dioxide: Crystal field splittings, absolute band intensities and complex refractive indices derived from infrared spectra

    NASA Technical Reports Server (NTRS)

    Khanna, R. K.; Zhao, Guizhi

    1986-01-01

    The infrared absorption spectra of thin crystalline films of sulfur dioxide at 90 K are reported in the 2700 to 450/cm region. The observed multiplicity of the spectral features in the regions of fundamentals is attributed to factor group splittings of the modes in a biaxial crystal lattice and the naturally present minor S-34, S-36, and O-18 isotopic species. Complex refractive indices determined by an iterative Kramers-Kronig analysis of the extinction data, and absolute band strengths derived from them, are also reported in this region.

  8. Absolute Line Intensities in the ν 3Band of 12CH 3F by Diode-Laser Spectroscopy

    NASA Astrophysics Data System (ADS)

    Lepère, Muriel; Blanquet, Ghislain; Walrand, Jacques

    1996-06-01

    Infrared absolute line intensities of the ν 3band of 12CH 3F have been measured around 9.5 μm using a diode-laser spectrometer. These line strengths were obtained from the equivalent width method and, for a few lines, by fitting a Rautian profile to the measured shape of the lines. From these results, we have deduced the vibrational bandstrength ( Sv0= 379.2 ± 5.9 cm -2·atm -1at 296 K) and the first Herman-Wallis factor (α = 0.35 × 10 -3± 0.10 × 10 -3).

  9. Absolute Line Intensities in the 2ν 02 Band of Cyanogen Chloride at 12.8 μm

    NASA Astrophysics Data System (ADS)

    Lepère, Muriel; Blanquet, Ghislain; Walrand, Jacques

    2000-05-01

    Absolute line intensities were measured at high resolution with a tunable diode laser. This work concerns the 2ν02 band of cyanogen chloride ClCN in the region 780 cm-1. Thirty-two absorption lines were recorded for the isotopomer 35ClCN and 26 lines for 37ClCN. From the analysis of these lines, we determined the bandstrengths: S0v = 19.14 cm-2 atm-1 for 35ClCN and S0v = 17.84 cm-2 atm-1 for 37ClCN.

  10. Incomplete photonic band gap as inferred from the speckle pattern of scattered light waves.

    PubMed

    Apalkov, V M; Raikh, M E; Shapiro, B

    2004-06-25

    Motivated by recent experiments on intensity correlations of the waves transmitted through disordered media, we demonstrate that the speckle pattern from disordered photonic crystal with incomplete band gap represents a sensitive tool for determination of the stop-band width. We establish the quantitative relation between this width and the angular anisotropy of the intensity correlation function.

  11. Absolute Rb one-color two-photon ionization cross-section measurement near a quantum interference

    SciTech Connect

    Takekoshi, T.; Brooke, G.M.; Patterson, B.M.; Knize, R.J.

    2004-05-01

    We observe destructive interference in the ground-state Rb two-photon ionization cross section when the single photon energy is tuned between the 5S{yields}5P and 5S{yields}6P transition energies. The minimum cross section is 5.9(1.5)x10{sup -52} cm{sup 4} s and it occurs at a wavelength of 441.0(3) nm (in vacuo). Relative measurements of these cross sections are made at various wavelengths by counting ions produced when magneto-optically trapped Rb atoms are exposed to light from a tunable pulsed laser. This relative curve is calibrated to an absolute cross-section measurement at 532 nm using the trap loss method. A simple calculation agrees reasonably with our results.

  12. Analysis of plasma-magnetic photonic crystal with a tunable band gap

    SciTech Connect

    Mehdian, H.; Mohammadzahery, Z.; Hasanbeigi, A.

    2013-04-15

    In this paper, electromagnetic wave propagation through the one-dimensional plasma-magnetic photonic crystal in the presence of external magnetic field has been analyzed. The dispersion relation, transmission and reflection coefficients have been obtained by using the transfer matrix method. It is investigated how photonic band gap of photonic crystals will be tuned when both dielectric function {epsilon} and magnetic permeability {mu} of the constitutive materials, depend on applied magnetic field. This is shown by one dimensional photonic crystals consisting of plasma and ferrite material layers stacked alternately.

  13. Photonic Band Gap via Quantum Coherence in Vortex Lattices of Bose-Einstein Condensates

    SciTech Connect

    Muestecaplioglu, Oe.E.; Oktel, M.Oe.

    2005-06-10

    We investigate the optical response of an atomic Bose-Einstein condensate with a vortex lattice. We find that it is possible for the vortex lattice to act as a photonic crystal and create photonic band gaps, by enhancing the refractive index of the condensate via a quantum coherent scheme. If high enough index contrast between the vortex core and the atomic sample is achieved, a photonic band gap arises depending on the healing length and the lattice spacing. A wide range of experimentally accessible parameters are examined and band gaps in the visible region of the electromagnetic spectrum are found. We also show how directional band gaps can be used to directly measure the rotation frequency of the condensate.

  14. Absolute Rovibrational Intensities of C-12O2-16 Absorption Bands in the 3090-3850/ CM Spectral Region

    NASA Technical Reports Server (NTRS)

    Devi, V. Malathy; Benner, D. Chris; Rinsland, Curtis P.; Smith, Mary Ann H.

    1998-01-01

    A multispectrum nonlinear least-squares fitting technique has been used to determine the absolute intensities for approximately 1500 spectral lines in 36 vibration - rotation bands Of C-12O2-16 between 3090 and 3850/ cm. A total of six absorption spectra of a high- purity (99.995% minimum) natural sample of carbon dioxide were used in the analysis. The spectral data (0.01/cm resolution) were recorded at room temperature and low pressure (1 to 10 Torr) using the McMath-Pierce Fourier transform spectrometer of the National Solar Observatory (NSO) on Kitt Peak. The absorption path lengths for these spectra varied between 24.86 and 385.76 m. The first experimental determination of the intensity of the theoretically predicted 2(nu)(sub 2, sup 2) + nu(sub 3) "forbidden" band has been made. The measured line intensities obtained for each band have been analyzed to determine the vibrational band intensity, S(sub nu), in /cm/( molecule/sq cm) at 296 K, square of the rotationless transition dipole moment |R|(exp 2) in Debye, as well as the nonrigid rotor coefficients. The results are compared to the values listed in the 1996 HITRAN database which are obtained using the direct numerical diagonalization (DND) technique as well as to other published values where available.

  15. Low index-contrast aperiodically ordered photonic quasicrystals for the development of isotropic photonic band-gap devices

    NASA Astrophysics Data System (ADS)

    Priya Rose, T.; Di Gennaro, E.; Andreone, A.; Abbate, G.

    2010-05-01

    Photonic quasicrystals (PQCs) have neither true periodicity nor translational symmetry, however they can exhibit symmetries that are not achievable by conventional periodic structures. The arbitrarily high rotational symmetry of these materials can be practically exploited to manufacture isotropic band gap materials, which are perfectly suitable for hosting waveguides or cavities. In this work, formation and development of the photonic bandgap (PBG) in twodimensional 8-, 10- and 12-fold symmetry quasicrystalline lattices of low dielectric contrast (0.4-0.6) were measured in the microwave region and compared with the PBG properties of a conventional hexagonal crystal. Band-gap properties were also investigated by changing the direction of propagation of the incident beam inside the crystal. Various angles of incidence from 0° to 30° were used in order to investigate the isotropic nature of the band-gap.

  16. Two-photon photoemission from a copper cathode in an X -band photoinjector

    NASA Astrophysics Data System (ADS)

    Li, H.; Limborg-Deprey, C.; Adolphsen, C.; McCormick, D.; Dunning, M.; Jobe, K.; Raubenheimer, T.; Vrielink, A.; Vecchione, T.; Wang, F.; Weathersby, S.

    2016-02-01

    This paper presents two-photon photoemission from a copper cathode in an X -band photoinjector. We experimentally verified that the electron bunch charge from photoemission out of a copper cathode scales with laser intensity (I) square for 400 nm wavelength photons. We compare this two-photon photoemission process with the single photon process at 266 nm. Despite the high reflectivity (R ) of the copper surface for 400 nm photons (R =0.48 ) and higher thermal energy of photoelectrons (two-photon at 200 nm) compared to 266 nm photoelectrons, the quantum efficiency of the two-photon photoemission process (400 nm) exceeds the single-photon process (266 nm) when the incident laser intensity is above 300 GW /cm2 . At the same laser pulse energy (E ) and other experimental conditions, emitted charge scales inversely with the laser pulse duration. A thermal emittance of 2.7 mm-mrad per mm root mean square (rms) was measured on our cathode which exceeds by sixty percent larger compared to the theoretical predictions, but this discrepancy is similar to previous experimental thermal emittance on copper cathodes with 266 nm photons. The damage of the cathode surface of our first-generation X -band gun from both rf breakdowns and laser impacts mostly explains this result. Using a 400 nm laser can substantially simplify the photoinjector system, and make it an alternative solution for compact pulsed electron sources.

  17. Achieving omnidirectional photonic band gap in sputter deposited TiO{sub 2}/SiO{sub 2} one dimensional photonic crystal

    SciTech Connect

    Jena, S. Tokas, R. B.; Sarkar, P.; Thakur, S.; Sahoo, N. K.; Haque, S. Maidul; Misal, J. S.; Rao, K. D.

    2015-06-24

    The multilayer structure of TiO{sub 2}/SiO{sub 2} (11 layers) as one dimensional photonic crystal (1D PC) has been designed and then fabricated by using asymmetric bipolar pulse DC magnetron sputtering technique for omnidirectional photonic band gap. The experimentally measured photonic band gap (PBG) in the visible region is well matched with the theoretically calculated band structure (ω vs. k) diagram. The experimentally measured omnidirectional reflection band of 44 nm over the incident angle range of 0°-70° is found almost matching within the theoretically calculated band.

  18. Landsat-7 ETM+ On-Orbit Reflective-Band Radiometric Stability and Absolute Calibration

    NASA Technical Reports Server (NTRS)

    Markham, Brian L.; Thome, Kurtis J.; Barsi, Julia A.; Kaita, Ed; Helder, Dennis L.; Barker, John L.

    2003-01-01

    The Landsat-7 spacecraft carries the Enhanced Thematic Mapper Plus (ETM+) instrument. This instrument images the Earth land surface in eight parts of the electromagnetic spectrum, termed spectral bands. These spectral images are used to monitor changes in the land surface, so a consistent relationship, i.e., calibration, between the image data and the Earth surface brightness, is required. The ETM+ has several on- board calibration devices that are used to monitor this calibration. The best on-board calibration source employs a flat white painted reference panel and has indicated changes of between 0.5% to 2% per year in the ETM+ response, depending on the spectral band. However, most of these changes are believed to be caused by changes in the reference panel, as opposed to changes in the instrument's sensitivity. This belief is based partially on on-orbit calibrations using instrumented ground sites and observations of "invariant sites", hyper-arid sites of the Sahara and Arabia. Changes determined from these data sets indicate are 0.1% - 0.6% per year. Tests and comparisons to other sensors also indicate that the uncertainty of the calibration is at the 5% level.

  19. Photonic band structures solved by a plane-wave-based transfer-matrix method.

    PubMed

    Li, Zhi-Yuan; Lin, Lan-Lan

    2003-04-01

    Transfer-matrix methods adopting a plane-wave basis have been routinely used to calculate the scattering of electromagnetic waves by general multilayer gratings and photonic crystal slabs. In this paper we show that this technique, when combined with Bloch's theorem, can be extended to solve the photonic band structure for 2D and 3D photonic crystal structures. Three different eigensolution schemes to solve the traditional band diagrams along high-symmetry lines in the first Brillouin zone of the crystal are discussed. Optimal rules for the Fourier expansion over the dielectric function and electromagnetic fields with discontinuities occurring at the boundary of different material domains have been employed to accelerate the convergence of numerical computation. Application of this method to an important class of 3D layer-by-layer photonic crystals reveals the superior convergency of this different approach over the conventional plane-wave expansion method.

  20. Fabrication of Ceramic Layer-by-Layer Infrared Wavelength Photonic Band Gap Crystals

    SciTech Connect

    Kang, Henry Hao-Chuan

    2004-12-19

    Photonic band gap (PBG) crystals, also known as photonic crystals, are periodic dielectric structures which form a photonic band gap that prohibit the propagation of electromagnetic (EM) waves of certain frequencies at any incident angles. Photonic crystals have several potential applications including zero-threshold semiconductor lasers, the inhibition of spontaneous emission, dielectric mirrors, and wavelength filters. If defect states are introduced in the crystals, light can be guided from one location to another or even a sharp bending of light in micron scale can be achieved. This generates the potential for optical waveguide and optical circuits, which will contribute to the improvement in the fiber-optic communications and the development of high-speed computers.

  1. Experimental Work With Photonic Band Gap Fiber: Building A Laser Electron Accelerator

    SciTech Connect

    Lincoln, Melissa; Ischebeck, Rasmus; Nobel, Robert; Siemann, Robert; /SLAC

    2006-09-29

    In the laser acceleration project E-163 at the Stanford Linear Accelerator Center, work is being done toward building a traveling wave accelerator that uses as its accelerating structure a length of photonic band gap fiber. The small scale of the optical fiber allows radiation at optical wavelengths to be used to provide the necessary accelerating energy. Optical wavelength driving energy in a small structure yields higher accelerating fields. The existence of a speed-of-light accelerating mode in a photonic band gap fiber has been calculated previously [1]. This paper presents an overview of several of the experimental challenges posed in the development of the proposed photonic band gap fiber accelerator system.

  2. Method of manufacturing flexible metallic photonic band gap structures, and structures resulting therefrom

    DOEpatents

    Gupta, Sandhya; Tuttle, Gary L.; Sigalas, Mihail; McCalmont, Jonathan S.; Ho, Kai-Ming

    2001-08-14

    A method of manufacturing a flexible metallic photonic band gap structure operable in the infrared region, comprises the steps of spinning on a first layer of dielectric on a GaAs substrate, imidizing this first layer of dielectric, forming a first metal pattern on this first layer of dielectric, spinning on and imidizing a second layer of dielectric, and then removing the GaAs substrate. This method results in a flexible metallic photonic band gap structure operable with various filter characteristics in the infrared region. This method may be used to construct multi-layer flexible metallic photonic band gap structures. Metal grid defects and dielectric separation layer thicknesses are adjusted to control filter parameters.

  3. Accidental degeneracy in photonic bands and topological phase transitions in two-dimensional core-shell dielectric photonic crystals.

    PubMed

    Xu, Lin; Wang, Hai-Xiao; Xu, Ya-Dong; Chen, Huan-Yang; Jiang, Jian-Hua

    2016-08-01

    A simple core-shell two-dimensional photonic crystal is studied where the triangular lattice symmetry and the C6 point group symmetry give rich physics in accidental touching points of photonic bands. We systematically evaluate different types of accidental nodal points at the Brillouin zone center for transverse-magnetic harmonic modes when the geometry and permittivity of the core-shell material are continuously tuned. The accidental nodal points can have different dispersions and topological properties (i.e., Berry phases). These accidental nodal points can be the critical states lying between a topological phase and a normal phase of the photonic crystal. They are thus very important for the study of topological photonic states. We show that, without breaking time-reversal symmetry, by tuning the geometry of the core-shell material, a phase transition into the photonic quantum spin Hall insulator can be achieved. Here the "spin" is defined as the orbital angular momentum of a photon. We study the topological phase transition as well as the properties of the edge and bulk states and their application potentials in optics. PMID:27505772

  4. Absolute frequency list of the ν3-band transitions of methane at a relative uncertainty level of 10(-11).

    PubMed

    Okubo, Sho; Nakayama, Hirotaka; Iwakuni, Kana; Inaba, Hajime; Sasada, Hiroyuki

    2011-11-21

    We determine the absolute frequencies of 56 rotation-vibration transitions of the ν(3) band of CH(4) from 88.2 to 90.5 THz with a typical uncertainty of 2 kHz corresponding to a relative uncertainty of 2.2 × 10(-11) over an average time of a few hundred seconds. Saturated absorption lines are observed using a difference-frequency-generation source and a cavity-enhanced absorption cell, and the transition frequencies are measured with a fiber-laser-based optical frequency comb referenced to a rubidium atomic clock linked to the international atomic time. The determined value of the P(7) F(2)((2)) line is consistent with the International Committee for Weights and Measures recommendation within the uncertainty.

  5. Band structure of germanium carbides for direct bandgap silicon photonics

    NASA Astrophysics Data System (ADS)

    Stephenson, C. A.; O'Brien, W. A.; Penninger, M. W.; Schneider, W. F.; Gillett-Kunnath, M.; Zajicek, J.; Yu, K. M.; Kudrawiec, R.; Stillwell, R. A.; Wistey, M. A.

    2016-08-01

    Compact optical interconnects require efficient lasers and modulators compatible with silicon. Ab initio modeling of Ge1-xCx (x = 0.78%) using density functional theory with HSE06 hybrid functionals predicts a splitting of the conduction band at Γ and a strongly direct bandgap, consistent with band anticrossing. Photoreflectance of Ge0.998C0.002 shows a bandgap reduction supporting these results. Growth of Ge0.998C0.002 using tetrakis(germyl)methane as the C source shows no signs of C-C bonds, C clusters, or extended defects, suggesting highly substitutional incorporation of C. Optical gain and modulation are predicted to rival III-V materials due to a larger electron population in the direct valley, reduced intervalley scattering, suppressed Auger recombination, and increased overlap integral for a stronger fundamental optical transition.

  6. Photon-induced positron annihilation lifetime spectroscopy using an S-band compact electron linac

    NASA Astrophysics Data System (ADS)

    Taira, Y.; Kuroda, R.; Tanaka, M.; Kumaki, M.; Oshima, N.; O'Rourke, B. E.; Suzuki, R.; Toyokawa, H.

    2014-02-01

    A new photon-induced positron annihilation lifetime spectroscopy approach has been developed using an S-band compact electron linac at the National Institute of Advanced Industrial Science and Technology (AIST). The high energy (<42MeV), intense (105 photons pulse-1), and ultra-short pulse (3 ps pulse width) photon beam creates positrons throughout an entire sample via pair production. A positron lifetime spectrum can be obtained by measuring the time difference between the accelerator's RF frequency and the detection time of the annihilation gamma rays. The positron lifetimes for lead and yttria-stabilized zirconia samples have been successfully measured.

  7. Ultranarrow-band photon-pair source compatible with solid state quantum memories and telecommunication networks.

    PubMed

    Fekete, Julia; Rieländer, Daniel; Cristiani, Matteo; de Riedmatten, Hugues

    2013-05-31

    We report on a source of ultranarrow-band photon pairs generated by widely nondegenerate cavity-enhanced spontaneous down-conversion. The source is designed to be compatible with Pr(3+) solid state quantum memories and telecommunication optical fibers, with signal and idler photons close to 606 nm and 1436 nm, respectively. Both photons have a spectral bandwidth around 2 MHz, matching the bandwidth of Pr(3+) doped quantum memories. This source is ideally suited for long distance quantum communication architectures involving solid state quantum memories.

  8. Ultranarrow-Band Photon-Pair Source Compatible with Solid State Quantum Memories and Telecommunication Networks

    NASA Astrophysics Data System (ADS)

    Fekete, Julia; Rieländer, Daniel; Cristiani, Matteo; de Riedmatten, Hugues

    2013-05-01

    We report on a source of ultranarrow-band photon pairs generated by widely nondegenerate cavity-enhanced spontaneous down-conversion. The source is designed to be compatible with Pr3+ solid state quantum memories and telecommunication optical fibers, with signal and idler photons close to 606 nm and 1436 nm, respectively. Both photons have a spectral bandwidth around 2 MHz, matching the bandwidth of Pr3+ doped quantum memories. This source is ideally suited for long distance quantum communication architectures involving solid state quantum memories.

  9. Omnidirectional photonic band gap enlarged by one-dimensional ternary unmagnetized plasma photonic crystals based on a new Fibonacci quasiperiodic structure

    SciTech Connect

    Zhang Haifeng; Liu Shaobin; Kong Xiangkun; Bian Borui; Dai Yi

    2012-11-15

    In this paper, an omnidirectional photonic band gap realized by one-dimensional ternary unmagnetized plasma photonic crystals based on a new Fibonacci quasiperiodic structure, which is composed of homogeneous unmagnetized plasma and two kinds of isotropic dielectric, is theoretically studied by the transfer matrix method. It has been shown that such an omnidirectional photonic band gap originates from Bragg gap in contrast to zero-n gap or single negative (negative permittivity or negative permeability) gap, and it is insensitive to the incidence angle and the polarization of electromagnetic wave. From the numerical results, the frequency range and central frequency of omnidirectional photonic band gap can be tuned by the thickness and density of the plasma but cease to change with increasing Fibonacci order. The bandwidth of omnidirectional photonic band gap can be notably enlarged. Moreover, the plasma collision frequency has no effect on the bandwidth of omnidirectional photonic band gap. It is shown that such new structure Fibonacci quasiperiodic one-dimensional ternary plasma photonic crystals have a superior feature in the enhancement of frequency range of omnidirectional photonic band gap compared with the conventional ternary and conventional Fibonacci quasiperiodic ternary plasma photonic crystals.

  10. Towards a complete photonic band gap in the visible

    NASA Astrophysics Data System (ADS)

    Velikov, K. P.

    2002-03-01

    The first part of the thesis describes the fabrication and the characterization of face-centered-cubic (fcc) photonic crystals (PCs) of dielectric (core-shell) spheres in a low-dielectric host (air). We demonstrate the synthesis and optical characterization of the PC's building blocks: well-defined core-shell colloidal particles and hollow shells of zinc sulfide (ZnS) and silica (SiO2). The synthesis method allows for the production of monodisperse particles with a tunable core-to-shell size ratio and total radius. By use of the controlled drying method, we demonstrate the fabrication of large planar PCs of well-defined thickness from SiO2, ZnS, and ZnS-core-SiO2-shell colloidal particles. We demonstrate, both experimentally and theoretically, that the relative stop gap width in the (111) fcc crystallographic direction in the case of high-index core and low-index shell spheres is larger than in a PC of homogeneous spheres of either material. The second part of the thesis focuses on the preparation and characterization of photonic materials of different degree of order made of metal colloidal particles. We demonstrate the synthesis and characterization of large (R > 100 nm) silver (Ag) particles. The particles are obtained by reducing silver nitrate with ascorbic acid in aqueous solutions in the presence of a protective polymer. The resulting particles are spherical porous aggregates with a low polydispersity (< 20%) and surface roughness on the order of a few nanometers. The optical properties on a single-particle level are well described if an effective dielectric constant is used. Depending on the volume fraction and the effective polydispersity, in water these particles form charge-stabilized glasses or crystals. Under illumination with white light, these samples display bright colors. A strong modulation is found in the reflectivity of photonic glasses possessing a short-range order only. The general features in the experimental spectra are found in the

  11. [Study on the axial strain sensor of birefringence photonic crystal fiber loop mirror based on the absolute integral of the monitoring peak].

    PubMed

    Jiang, Ying; Zeng, Jie; Liang, Da-Kai; Wang, Xue-Liang; Ni, Xiao-Yu; Zhang, Xiao-Yan; Li, Ji-Feng; Luo, Wen-Yong

    2013-12-01

    In the present paper, the theoretical expression of the wavelength change and the axial strain of birefringence fiber loop mirror is developed. The theoretical result shows that the axial strain sensitivity of birefringence photonic crystal fiber loop mirror is much lower than conventional birefringence fiber loop mirror. It is difficult to measure the axial strain by monitoring the wavelength change of birefringence photonic crystal fiber loop mirror, and it is easy to cause the measurement error because the output spectrum is not perfectly smooth. The different strain spectrum of birefringence photonic crystal fiber loop mirror was measured experimentally by an optical spectrum analyzer. The measured spectrum was analysed. The results show that the absolute integral of the monitoring peak decreases with increasing strain and the absolute integral is linear versus strain. Based on the above results, it is proposed that the axial strain can be measured by monitoring the absolute integral of the monitoring peak in this paper. The absolute integral of the monitoring peak is a comprehensive index which can indicate the light intensity of different wavelength. This method of monitoring the absolute integral of the monitoring peak to measure the axial strain can not only overcome the difficulty of monitoring the wavelength change of birefringence photonic crystal fiber loop mirror, but also reduce the measurement error caused by the unsmooth output spectrum. PMID:24611385

  12. Fabrication of substrates for photonic band gap crystals growth

    NASA Astrophysics Data System (ADS)

    Bassène, Seydou; Lessard, Roger A.

    2006-09-01

    We present a technical processing to fabricate substrates (fused silica) for 3-D photonic bandgap material. The potential surface was modified to improve the colloidal method for nanoparticles assembly. This method allows orientating the growth of the colloidal crystals in a specific way; the crystalline plans growth is parallel to the surface of the substrate, and we can eliminate stacking defects and polycrystallinity. The substrate is obtained with ions beam engraving, according to the following process: A layer of photoresist is deposited on the substrate; we write two identical holographic gratings on the photoresist with 90° angle; After the development of photoresist, we obtain a profile which corresponds to one of the crystalline plans of the face centered cubic lattice; This profile will be transferred on the substrate by RIE (reactive ion etching). This substrate has many advantages: it is reusable because it is easily cleaned with solvents like acetone; the same substrate will be easy to use in order to make several growth tests and to optimize physicochemical parameters during artificial opals fabrication.

  13. A rare gas optics-free absolute photon flux and energy analyzer for solar and planetary observations

    NASA Technical Reports Server (NTRS)

    Judge, Darrell L.

    1994-01-01

    We have developed a prototype spectrometer for space applications requiring long term absolute EUV photon flux measurements. In this recently developed spectrometer, the energy spectrum of the incoming photons is transformed directly into an electron energy spectrum by taking advantage of the photoelectric effect in one of several rare gases at low pressures. Using an electron energy spectrometer, followed by an electron multiplier detector, pulses due to individual electrons are counted. The overall efficiency of this process can be made essentially independent of gain drifts in the signal path, and the secular degradation of optical components which is often a problem in other techniques is avoided. A very important feature of this approach is its freedom from the problem of overlapping spectral orders that plagues grating EUV spectrometers. An instrument with these features has not been flown before, but is essential to further advances in our understanding of solar EUV flux dynamics, and the coupled dynamics of terrestrial and planetary atmospheres. The detailed characteristics of this optics-free spectrometer are presented in the publications section.

  14. Band gap of two-dimensional fiber-air photonic crystals

    NASA Astrophysics Data System (ADS)

    Yang, Shu; Li, Masha

    2016-04-01

    A two-dimensional photonic crystal (PC) composed of textile fiber and air is initially discussed in this paper. Textile materials are so called soft materials, which are different from the previous PCs composed of rigid materials. The plain wave expansion method is used to calculate band structure of different PCs by altering component properties or structural parameters. Results show that the dielectric constant of textile fibers, fiber filling ratio and lattice arrangement are effective factors which influence PCs' band gap. Yet lattice constant and fiber diameter make inconspicuous influence on the band gap feature.

  15. Planar Defect Modes Excited at the Band Edge of Three-dimensional Photonic Crystals

    NASA Astrophysics Data System (ADS)

    Iida, Masaru; Tani, Masahiko; Sakai, Kiyomi; Watanabe, Masayoshi; Kitahara, Hideaki; Tohme, Takuya; Wada Takeda, Mitsuo

    2004-09-01

    We experimentally and numerically studied planar defect modes excited at band-edge resonant mode frequencies in three-dimensional photonic crystals. We identified the observed peaks as the defect modes using the spectrum calculated at the defect layer. The spectrum also clarifies the difference between these modes and ordinary band-edge resonant modes. The calculated spatial distribution of the electric field in the defect modes shows that the defect modes have a characteristic field concentration in the band-edge resonant mode.

  16. Hidden-sector photon and axion searches using photonic band gap structures

    NASA Astrophysics Data System (ADS)

    Seviour, Rebecca; Bailey, Ian; Woollett, Nathan; Williams, Peter

    2014-03-01

    Many proposed extensions of the standard model of particle physics predict the existence of weakly interacting sub-eV particles (WISPs) such as hidden-sector photons and axions, which are also of interest as dark matter candidates. In this paper we propose a novel experimental approach in which microwave photonic lattice structures form part of a ‘light shining through the wall’-type experiment to search for WISPs. We demonstrate the potential to match and exceed the sensitivities of conventional experiments operating in the microwave regime.

  17. Light reflector, amplifier, and splitter based on gain-assisted photonic band gaps

    NASA Astrophysics Data System (ADS)

    Zhang, Yan; Liu, Yi-Mou; Zheng, Tai-Yu; Wu, Jin-Hui

    2016-07-01

    We study both the steady and the dynamic optical response of cold atoms trapped in an optical lattice and driven to the three-level Λ configuration. These atoms are found to exhibit gain without population inversion when an incoherent pump is applied to activate spontaneously generated coherence. Gain-assisted double photonic band gaps characterized by reflectivities over 100% then grow up near the probe resonance due to the periodic distribution of the atomic density. These band gaps along with the neighboring allowed bands of transmissivities over 100% can be tuned by modulating the control field in amplitude, frequency, and, especially, phase. Consequently it is viable to realize a reflector, an amplifier, or a splitter when a weak incident light pulse is totally reflected in the photonic band gaps, totally transmitted in the allowed bands, or equally reflected and transmitted in the intersecting regions. Our results have potential applications in all-optical networks with respect to fabricating dynamically switchable devices for manipulating photon flows at low-light levels.

  18. The Development of Layered Photonic Band Gap Structures Using a Micro-Transfer Molding Technique

    SciTech Connect

    Kevin Jerome Sutherland

    2001-05-01

    Photonic band gap (PBG) crystals are periodic dielectric structures that manipulate electromagnetic radiation in a manner similar to semiconductor devices manipulating electrons. Whereas a semiconductor material exhibits an electronic band gap in which electrons cannot exist, similarly, a photonic crystal containing a photonic band gap does not allow the propagation of specific frequencies of electromagnetic radiation. This phenomenon results from the destructive Bragg diffraction interference that a wave propagating at a specific frequency will experience because of the periodic change in dielectric permitivity. This gives rise to a variety of optical applications for improving the efficiency and effectiveness of opto-electronic devices. These applications are reviewed later. Several methods are currently used to fabricate photonic crystals, which are also discussed in detail. This research involves a layer-by-layer micro-transfer molding ({mu}TM) and stacking method to create three-dimensional FCC structures of epoxy or titania. The structures, once reduced significantly in size can be infiltrated with an organic gain media and stacked on a semiconductor to improve the efficiency of an electronically pumped light-emitting diode. Photonic band gap structures have been proven to effectively create a band gap for certain frequencies of electro-magnetic radiation in the microwave and near-infrared ranges. The objective of this research project was originally two-fold: to fabricate a three dimensional (3-D) structure of a size scaled to prohibit electromagnetic propagation within the visible wavelength range, and then to characterize that structure using laser dye emission spectra. As a master mold has not yet been developed for the micro transfer molding technique in the visible range, the research was limited to scaling down the length scale as much as possible with the current available technology and characterizing these structures with other methods.

  19. 160 Gbit/s photonics wireless transmission in the 300-500 GHz band

    NASA Astrophysics Data System (ADS)

    Yu, X.; Jia, S.; Hu, H.; Galili, M.; Morioka, T.; Jepsen, P. U.; Oxenløwe, L. K.

    2016-11-01

    To accommodate the ever increasing wireless traffic in the access networks, considerable efforts have been recently invested in developing photonics-assisted wireless communication systems with very high data rates. Superior to photonic millimeter-wave systems, terahertz (THz) band (300 GHz-10 THz) provides a much larger bandwidth and thus promises an extremely high capacity. However, the capacity potential of THz wireless systems has by no means been achieved yet. Here, we successfully demonstrate 160 Gbit/s wireless transmission by using a single THz emitter and modulating 25 GHz spaced 8 channels (20 Gbps per channel) in the 300-500 GHz band, which is the highest bitrate in the frequency band above 300 GHz, to the best of our knowledge.

  20. A photonic crystal waveguide with silicon on insulator in the near-infrared band

    NASA Astrophysics Data System (ADS)

    Tang, Hai-Xia; Zuo, Yu-Hua; Yu, Jin-Zhong; Wang, Qi-Ming

    2007-07-01

    A two-dimensional (2D) photonic crystal waveguide in the Γ-K direction with triangular lattice on a silicon-on-insulator (SOI) substrate in the near-infrared band is fabricated by the combination of electron beam lithography and inductively coupled plasma etching. Its transmission characteristics are analysed from the stimulated band diagram by the effective index and the 2D plane wave expansion (PWE) methods. In the experiment, the transmission band edge in a longer wavelength of the photonic crystal waveguide is about 1590 nm, which is in good qualitative agreement with the simulated value. However, there is a disagreement between the experimental and the simulated results when the wavelength ranges from 1607 to 1630 nm, which can be considered as due to the unpolarized source used in the transmission measurement.

  1. Theoretical aspects of photonic band gap in 1D nano structure of LN: MgLN periodic layer

    SciTech Connect

    Sisodia, Namita

    2015-06-24

    By using the transfer matrix method, we have analyzed the photonic band gap properties in a periodic layer of LN:MgLN medium. The Width of alternate layers of LN and MgLN is in the range of hundred nanometers. The birefringent and ferroelectric properties of the medium (i.e ordinary, extraordinary refractive indices and electric dipole moment) is given due considerations in the formulation of photonic band gap. Effect of electronic transition dipole moment of the medium on photonic band gap is also taken into account. We find that photonic band gap can be modified by the variation in the ratio of the width of two medium. We explain our findings by obtaining numerical values and the effect on the photonic band gap due to variation in the ratio of alternate medium is shown graphically.

  2. Hydrogen production by Tuning the Photonic Band Gap with the Electronic Band Gap of TiO2

    NASA Astrophysics Data System (ADS)

    Waterhouse, G. I. N.; Wahab, A. K.; Al-Oufi, M.; Jovic, V.; Anjum, D. H.; Sun-Waterhouse, D.; Llorca, J.; Idriss, H.

    2013-10-01

    Tuning the photonic band gap (PBG) to the electronic band gap (EBG) of Au/TiO2 catalysts resulted in considerable enhancement of the photocatalytic water splitting to hydrogen under direct sunlight. Au/TiO2 (PBG-357 nm) photocatalyst exhibited superior photocatalytic performance under both UV and sunlight compared to the Au/TiO2 (PBG-585 nm) photocatalyst and both are higher than Au/TiO2 without the 3 dimensionally ordered macro-porous structure materials. The very high photocatalytic activity is attributed to suppression of a fraction of electron-hole recombination route due to the co-incidence of the PBG with the EBG of TiO2 These materials that maintain their activity with very small amount of sacrificial agents (down to 0.5 vol.% of ethanol) are poised to find direct applications because of their high activity, low cost of the process, simplicity and stability.

  3. Experimental and Theoretical Studies of Photonic Band gaps in Artificial Opals

    NASA Astrophysics Data System (ADS)

    Wang, Lei; Yin, Ming; Arammash, Fouzi; Datta, Timir

    2014-03-01

    Photonic band structure and band gap were numerically computed for a number of closed packed simple cubic and Hexagonal arrangements of non-conducting spheres using ``Finite Difference Time Domain Method''. Photonic gaps were found to exist in the simple cubic overlapping spheres with index of refraction (n) >3.2. Gap increased linearly from 0.117- 0.161 (1/micron) as lattice constant decreased from 0.34 to 0.18 (micron). For less than 3.2 no gap was obtained. Also, no gaps were obtained for hexagonal packing. UV-VIS reflectivity and transmission measurements of polycrystalline bulk artificial opals of silica (SiO2) spheres, ranging from 250nm to 300nm in sphere diameter indicate a reflection peak in the 500-600 nm regimes. Consistent with photonic band gap behavior we find that reflectivity is enhanced in the same wavelength where transmission is reduced. To the best of our knowledge this is the first observation of photonic gap in the visible wave length under ambient conditions. The wave length at the reflectance peak increases with the diameter of the SiO2 spheres, and is approximately twice the diameter following Bragg reflection. DOD Award No 60177-RT-H from ARO.

  4. Two-Photon Absorption by H2 Molecules: Origin of the 2175A Astronomical Band?

    NASA Astrophysics Data System (ADS)

    Sorokin, Peter P.; Glownia, James H.

    2007-04-01

    The near UV spectra of OB stars are often dominated by a broad extinction band peaking at 2175A. Forty years after its discovery, the origin of this band remains unknown, although it is usually attributed to linear scattering or linear absorption by interstellar dust particles. Here we report that two-photon absorption by H2 molecules in gaseous clouds enveloping OB stars should lead to a strong band peaking near 2175A. We first show that if the product of the H2 density in the gaseous cloud times the emitted stellar VUV flux is sufficiently great, the threshold for stimulated Rayleigh scattering will be exceeded, resulting in the generation of intense, monochromatic VUV light at the rest frame frequencies of H2 B- and C-state resonance lines originating from levels J''=0 and J''=1 of X0. This coherently generated light must necessarily propagate radially inwards towards the photosphere of the illuminating OB star, and therefore cannot be detected externally. However, this same light effectively constitutes intense ``first step'' monochromatic radiation that should induce continuum photons emitted by the OB star near 2175A to be strongly absorbed as ``second steps'' in resonantly-enhanced H2 two-photon transitions to two well known doubly-excited dissociative states of H2. Archival UV and VUV spectra of 185 OB stars strongly support our nonlinear model for the 2175A band.

  5. Demonstration of flat-band image transmission in optically induced Lieb photonic lattices.

    PubMed

    Xia, Shiqiang; Hu, Yi; Song, Daohong; Zong, Yuanyuan; Tang, Liqin; Chen, Zhigang

    2016-04-01

    We present a simple, yet effective, approach for optical induction of Lieb photonic lattices, which typically rely on the femtosecond laser writing technique. Such lattices are established by judiciously overlapping two sublattices (an "egg-crate" lattice and a square lattice) with different periodicities through a self-defocusing photorefractive medium. Furthermore, taking advantage of the superposition of localized flat-band states inherent in the Lieb lattices, we demonstrate distortion-free image transmission in such two-dimensional perovskite-like photonic structures. Our experimental observations find good agreement with numerical simulations.

  6. Two-dimensional phononic-photonic band gap optomechanical crystal cavity.

    PubMed

    Safavi-Naeini, Amir H; Hill, Jeff T; Meenehan, Seán; Chan, Jasper; Gröblacher, Simon; Painter, Oskar

    2014-04-18

    We present the fabrication and characterization of an artificial crystal structure formed from a thin film of silicon that has a full phononic band gap for microwave X-band phonons and a two-dimensional pseudo-band gap for near-infrared photons. An engineered defect in the crystal structure is used to localize optical and mechanical resonances in the band gap of the planar crystal. Two-tone optical spectroscopy is used to characterize the cavity system, showing a large coupling (g0/2π≈220  kHz) between the fundamental optical cavity resonance at ωo/2π=195  THz and colocalized mechanical resonances at frequency ωm/2π≈9.3  GHz.

  7. Isotropic properties of the photonic band gap in quasicrystals with low-index contrast

    NASA Astrophysics Data System (ADS)

    Priya Rose, T.; di Gennaro, E.; Abbate, G.; Andreone, A.

    2011-09-01

    We report on the formation and development of the photonic band gap in two-dimensional 8-, 10-, and 12-fold symmetry quasicrystalline lattices of low-index contrast. Finite-size structures made of dielectric cylindrical rods were studied and measured in the microwave region, and their properties were compared with a conventional hexagonal crystal. Band-gap characteristics were investigated by changing the direction of propagation of the incident beam inside the crystal. Various angles of incidence from 0∘ to 30∘ were used to investigate the isotropic nature of the band gap. The arbitrarily high rotational symmetry of aperiodically ordered structures could be practically exploited to manufacture isotropic band-gap materials, which are perfectly suitable for hosting waveguides or cavities.

  8. Theory of a one-atom laser in a photonic band-gap microchip

    SciTech Connect

    Florescu, Lucia; John, Sajeev; Quang Tran; Wang Rongzhou

    2004-01-01

    We present a quantum theory of a coherently pumped two-level atom in a photonic band gap (PBG), coupled to both a multimode waveguide channel and a high-quality microcavity embedded within a photonic crystal. One mode is engineered to exhibit a sharp cutoff within the PBG, leading to a large discontinuity in the local photon density of states near the atom, and the cavity field mode is resonant with the central component of the Mollow spectrum of atomic resonance fluorescence. Another mode of the waveguide channel is used to propagate the pump beam. We derive analytical expressions for the optical amplitude, intensity, second-order correlation functions, and conjugate quadrature variances for the light emitted by the atom into the microcavity. The quantum degree of second-order coherence in the cavity field reveals enhanced, inversionless, nearly coherent light generation when the photon density of states jump between the Mollow spectral components is large. The cavity field characteristics are highly distinct from that of a corresponding high-Q cavity in ordinary vacuum. In the case of a vanishing photon density of states on the lower Mollow sideband and no dipolar dephasing, the emitted photon statistics is Poissonian, and the cavity field exhibits quadrature coherence.

  9. Absolute band intensities in the nu19/nu23 (530 cm(-1)) and nu7 (777 cm(-1)) bands of acetone ((CH3)2CO) from 232 to 295 K

    NASA Technical Reports Server (NTRS)

    Wang, W. F.; Stevenson, A.; Reuter, D. C.; Sirota, J. M.

    2000-01-01

    Absolute band intensities of acetone ((CH3)2CO) in the nu19/nu23 and nu7 band systems near 530 and 777 cm(-1), respectively, were measured at temperatures of 232, 262 and 295 K, using a Fourier transform infrared (FTIR) spectrometer. No evident temperature dependence for the band intensities was observed. The dipole moments and the fundamental band intensities were derived in the harmonic oscillator approximation. The results are useful for the spectroscopic retrieval of acetone concentrations in the upper atmosphere.

  10. Tunable diode laser measurements of absolute line strengths in the 2nu2 band of N2O near 8 microns

    NASA Technical Reports Server (NTRS)

    Tang, Lai-Wa; Daunt, Stephen J.; Nadler, Shachar

    1989-01-01

    The absolute intensities of five rotational transitions in the 2nu2 band of N2O near 8 microns have been measured with a tunable-diode laser-spectrometer. Measurements were reproducible within an average deviation of about 3 percent, and the experimental and calculated line strengths differed by only 1.5 percent. An analysis of the line strengths has yielded a band strength of S(v) = 6.98 + or - 0.26/sq cm per atm at 296 K. The band and line strengths are in excellent agreement with two recently reported values obtained by using Fourier transform-IR spectroscopy.

  11. Atom–atom interactions around the band edge of a photonic crystal waveguide

    PubMed Central

    Hood, Jonathan D.; Goban, Akihisa; Asenjo-Garcia, Ana; Lu, Mingwu; Yu, Su-Peng; Chang, Darrick E.; Kimble, H. J.

    2016-01-01

    Tailoring the interactions between quantum emitters and single photons constitutes one of the cornerstones of quantum optics. Coupling a quantum emitter to the band edge of a photonic crystal waveguide (PCW) provides a unique platform for tuning these interactions. In particular, the cross-over from propagating fields E(x)∝e±ikxx outside the bandgap to localized fields E(x)∝e−κx|x| within the bandgap should be accompanied by a transition from largely dissipative atom–atom interactions to a regime where dispersive atom–atom interactions are dominant. Here, we experimentally observe this transition by shifting the band edge frequency of the PCW relative to the D1 line of atomic cesium for N¯=3.0±0.5 atoms trapped along the PCW. Our results are the initial demonstration of this paradigm for coherent atom–atom interactions with low dissipation into the guided mode. PMID:27582467

  12. Anomalous behavior of group velocity and index of refraction in a defect photonic band gap structure

    NASA Astrophysics Data System (ADS)

    Srivastava, Sanjeev K.; Pandey, G. N.; Ojha, S. P.

    2008-02-01

    In the present paper, we have made an analysis to observe the effect of introduction of defect on dispersion relation, group velocity, and effective group index in a conventional photonic band gap (PBG) structure. The study shows that inside the PBG materials group velocity and effective group index becomes negative in both types (conventional as well as defect PBG structure) of structure at a certain range of frequencies. Also, near the edges of the bands it attains very high values of index of refraction. A defect PBG structure gives a very unique feature that group velocity becomes exactly zero at a particular value of frequency and also becomes several hundred times greater than the velocity of light which is not attainable with the conventional PBG structure. Defect PBG structures with such peculiar characteristics are seen in lasing without inversion, in construction of perfect lens, in trapping of photon and other optical devices.

  13. Photonic Generation of Dual-Band Power-Efficient Millimeter-Wave UWB Signals

    NASA Astrophysics Data System (ADS)

    Xiang, Peng; Guo, Hao; Chen, Dalei; Zhou, Hua

    2015-05-01

    Ultra-wideband (UWB) technology has attracted great interest because it can provide a promising solution of future radar and short-range broadband wireless communications. The generation of millimeter-wave UWB signals using photonic approaches can reduce the high cost of the millimeter-wave electrical circuits. Moreover, it is well compatible with fiber transmission, which can effectively extend its signal coverage. In this paper, a novel approach to the photonic generation of millimeter-wave UWB signals with dual-band operation consideration is proposed. The proposed scheme can simultaneously generate millimeter-wave UWB signals in both 24 GHz and 60 GHz millimeter band, and can efficiently exploit the spectrum limit allowed by the FCC mask by using the linear combination pulse design concept. A model describing the proposed system is developed and the generation of 24/60 GHz millimeter-wave UWB signals is demonstrated via computer simulations.

  14. Photonic stop bands in quasi-random nanoporous anodic alumina structures

    NASA Astrophysics Data System (ADS)

    Maksymov, Ivan; Ferré-Borrull, Josep; Pallarès, Josep; Marsal, Lluis F.

    2012-10-01

    The existence of photonic stop bands in the self-assembled arrangement of pores in porous anodic alumina structures is investigated by means of rigorous 2D finite-difference time-domain calculations. Self-assembled porous anodic alumina shows a random distribution of domains, each of them with a very definite triangular pattern, constituting a quasi-random structure. The observed stop bands are similar to those of photonic quasicrystals or random structures. As the pores of nanoporous anodic alumina can be infiltrated with noble metals, nonlinear or active media, it makes this material very attractive and cost-effective for applications including inhibition of spontaneous emission, random lasing, LEDs and biosensors.

  15. Periodic dielectric structure for production of photonic band gap and method for fabricating the same

    DOEpatents

    Ozbay, Ekmel; Tuttle, Gary; Michel, Erick; Ho, Kai-Ming; Biswas, Rana; Chan, Che-Ting; Soukoulis, Costas

    1995-01-01

    A method for fabricating a periodic dielectric structure which exhibits a photonic band gap. Alignment holes are formed in a wafer of dielectric material having a given crystal orientation. A planar layer of elongate rods is then formed in a section of the wafer. The formation of the rods includes the step of selectively removing the dielectric material of the wafer between the rods. The formation of alignment holes and layers of elongate rods and wafers is then repeated to form a plurality of patterned wafers. A stack of patterned wafers is then formed by rotating each successive wafer with respect to the next-previous wafer, and then placing the successive wafer on the stack. This stacking results in a stack of patterned wafers having a four-layer periodicity exhibiting a photonic band gap.

  16. Atom-atom interactions around the band edge of a photonic crystal waveguide.

    PubMed

    Hood, Jonathan D; Goban, Akihisa; Asenjo-Garcia, Ana; Lu, Mingwu; Yu, Su-Peng; Chang, Darrick E; Kimble, H J

    2016-09-20

    Tailoring the interactions between quantum emitters and single photons constitutes one of the cornerstones of quantum optics. Coupling a quantum emitter to the band edge of a photonic crystal waveguide (PCW) provides a unique platform for tuning these interactions. In particular, the cross-over from propagating fields [Formula: see text] outside the bandgap to localized fields [Formula: see text] within the bandgap should be accompanied by a transition from largely dissipative atom-atom interactions to a regime where dispersive atom-atom interactions are dominant. Here, we experimentally observe this transition by shifting the band edge frequency of the PCW relative to the [Formula: see text] line of atomic cesium for [Formula: see text] atoms trapped along the PCW. Our results are the initial demonstration of this paradigm for coherent atom-atom interactions with low dissipation into the guided mode. PMID:27582467

  17. Periodic dielectric structure for production of photonic band gap and method for fabricating the same

    DOEpatents

    Ozbay, E.; Tuttle, G.; Michel, E.; Ho, K.M.; Biswas, R.; Chan, C.T.; Soukoulis, C.

    1995-04-11

    A method is disclosed for fabricating a periodic dielectric structure which exhibits a photonic band gap. Alignment holes are formed in a wafer of dielectric material having a given crystal orientation. A planar layer of elongate rods is then formed in a section of the wafer. The formation of the rods includes the step of selectively removing the dielectric material of the wafer between the rods. The formation of alignment holes and layers of elongate rods and wafers is then repeated to form a plurality of patterned wafers. A stack of patterned wafers is then formed by rotating each successive wafer with respect to the next-previous wafer, and then placing the successive wafer on the stack. This stacking results in a stack of patterned wafers having a four-layer periodicity exhibiting a photonic band gap. 42 figures.

  18. Atom-atom interactions around the band edge of a photonic crystal waveguide.

    PubMed

    Hood, Jonathan D; Goban, Akihisa; Asenjo-Garcia, Ana; Lu, Mingwu; Yu, Su-Peng; Chang, Darrick E; Kimble, H J

    2016-09-20

    Tailoring the interactions between quantum emitters and single photons constitutes one of the cornerstones of quantum optics. Coupling a quantum emitter to the band edge of a photonic crystal waveguide (PCW) provides a unique platform for tuning these interactions. In particular, the cross-over from propagating fields [Formula: see text] outside the bandgap to localized fields [Formula: see text] within the bandgap should be accompanied by a transition from largely dissipative atom-atom interactions to a regime where dispersive atom-atom interactions are dominant. Here, we experimentally observe this transition by shifting the band edge frequency of the PCW relative to the [Formula: see text] line of atomic cesium for [Formula: see text] atoms trapped along the PCW. Our results are the initial demonstration of this paradigm for coherent atom-atom interactions with low dissipation into the guided mode.

  19. UV-VIS regime band gap in a 3-d photonic system

    NASA Astrophysics Data System (ADS)

    Yin, Ming; Arammash, Fouzi; Datta, Timir; Tsu, Ray

    2013-03-01

    Synthetic opals are self-organized bulk, close packed systems that are three-dimensionally ordered with periodicity determined by the sphere diameter. These materials have been used as templates for nano devices with novel properties. For example, in carbon inverse opals show quantum hall effect and related magneto electric responses. Inverse are also reported to show photonic band gap. It is expected that devices based on these materials will be an alternative to electronic devices. These opal specimens were hexagonal or face centered cubic crystals with silica sphere diameter ranging between 220 nm and 270nm. Here we will present results of structural and imaging studies such as SEM, AFM and XRD. In addition results of the (UV-VIS) optical behavior will be provided. The optical response will be analyzed in terms of photonic band gaps in the sub-micrometer optical and UV regime.

  20. A versatile optical junction using photonic band-gap guidance and self collimation

    SciTech Connect

    Gupta, Man Mohan; Medhekar, Sarang

    2014-09-29

    We show that it is possible to design two photonic crystal (PC) structures such that an optical beam of desired wavelength gets guided within the line defect of the first structure (photonic band gap guidance) and the same beam gets guided in the second structure by self-collimation. Using two dimensional simulation of a design made of the combination of these two structures, we propose an optical junction that allows for crossing of two optical signals of same wavelength and same polarization with very low crosstalk. Moreover, the junction can be operated at number of frequencies in a wide range. Crossing of multiple beams with very low cross talk is also possible. The proposed junction should be important in future integrated photonic circuits.

  1. Photonic vector signal generation at microwave/millimeter-wave bands employing an optical frequency quadrupling scheme.

    PubMed

    Lin, Chun-Ting; Shih, Po-Tsung; Jiang, Wen-Jr; Wong, Er-Zih; Chen, Jason Jyehong; Chi, Sien

    2009-07-15

    To the best of our knowledge, a novel photonic architecture to generate vector signals at microwave/millimeter-wave bands employing an optical frequency quadrupling technique based on an external dual-parallel modulator is proposed for the first time. A 312.5 MSym/s quadruple phase-shift keying signal at 25 GHz is experimentally demonstrated using properly precoding driving signal at 6.25 GHz, and optical power penalty is negligible following 50 km single-mode fiber transmission.

  2. High brightness photonic band crystal semiconductor lasers in the passive mode locking regime

    SciTech Connect

    Rosales, R.; Kalosha, V. P.; Miah, M. J.; Bimberg, D.; Posilović, K.; Pohl, J.; Weyers, M.

    2014-10-20

    High brightness photonic band crystal lasers in the passive mode locking regime are presented. Optical pulses with peak power of 3 W and peak brightness of about 180 MW cm{sup −2} sr{sup −1} are obtained on a 5 GHz device exhibiting 15 ps pulses and a very low beam divergence in both the vertical and horizontal directions.

  3. Precision X-Band Linac Technologies for Nuclear Photonics Gamma-Ray Sources

    SciTech Connect

    Hartemann, F V; Albert, F; Anderson, S G; Bayramian, A J; Cross, R R; Ebbers, C A; Gibson, D J; Houck, T L; Marsh, R A; Messerly, M J; Siders, C W; McNabb, D P; Barty, C J; Adolphsen, C E; Chu, T S; Jongewaard, E N; Tantawi, S G; Vlieks, A E; Wang, F; Wang, J W; Raubenheimer, T O; Ighigeanu, D; Toma, M; Cutoiu, D

    2011-08-31

    Nuclear photonics is an emerging field of research requiring new tools, including high spectral brightness, tunable gamma-ray sources; high photon energy, ultrahigh-resolution crystal spectrometers; and novel detectors. This presentation focuses on the precision linac technology required for Compton scattering gamma-ray light sources, and on the optimization of the laser and electron beam pulse format to achieve unprecedented spectral brightness. Within this context, high-gradient X-band technology will be shown to offer optimal performance in a compact package, when used in conjunction with the appropriate pulse format, and photocathode illumination and interaction laser technologies. The nascent field of nuclear photonics is enabled by the recent maturation of new technologies, including high-gradient X-band electron acceleration, robust fiber laser systems, and hyper-dispersion CPA. Recent work has been performed at LLNL to demonstrate isotope-specific detection of shielded materials via NRF using a tunable, quasi-monochromatic Compton scattering gamma-ray source operating between 0.2 MeV and 0.9 MeV photon energy. This technique is called Fluorescence Imaging in the Nuclear Domain with Energetic Radiation (or FINDER). This work has, among other things, demonstrated the detection of {sup 7}Li shielded by Pb, utilizing gamma rays generated by a linac-driven, laser-based Compton scattering gamma-ray source developed at LLNL. Within this context, a new facility is currently under construction at LLNL, with the goal of generating tunable {gamma}-rays in the 0.5-2.5 MeV photon energy range, at a repetition rate of 120 Hz, and with a peak brightness in the 10{sup 20} photons/(s x mm{sup 2} x mrad{sup 2} x 0.1% bw).

  4. All-optical dynamical Casimir effect in a three-dimensional terahertz photonic band gap

    NASA Astrophysics Data System (ADS)

    Hagenmüller, David

    2016-06-01

    We identify an architecture for the observation of all-optical dynamical Casimir effect in realistic experimental conditions. We suggest that by integrating quantum wells in a three-dimensional (3D) photonic band-gap material made out of large-scale (˜200 -μ m ) germanium logs, it is possible to achieve ultrastrong light-matter coupling at terahertz frequencies for the cyclotron transition of a two-dimensional electron gas interacting with long-lived optical modes, in which vacuum Rabi splitting is comparable to the Landau level spacing. When a short, intense electromagnetic transient of duration ˜250 fs and carrying a peak magnetic field ˜5 T is applied to the structure, the cyclotron transition can be suddenly tuned on resonance with a desired photon mode, switching on the light-matter interaction and leading to a Casimir radiation emitted parallel to the quantum well plane. The radiation spectrum consists of sharp peaks with frequencies coinciding with engineered optical modes within the 3D photonic band gap, and its characteristics are extremely robust to the nonradiative damping which can be large in our system. Furthermore, the absence of continuum with associated low-energy excitations for both electromagnetic and electronic quantum states can prevent the rapid absorption of the photon flux which is likely to occur in other proposals for all-optical dynamical Casimir effect.

  5. Analogy of transistor function with modulating photonic band gap in electromagnetically induced grating.

    PubMed

    Wang, Zhiguo; Ullah, Zakir; Gao, Mengqin; Zhang, Dan; Zhang, Yiqi; Gao, Hong; Zhang, Yanpeng

    2015-09-09

    Optical transistor is a device used to amplify and switch optical signals. Many researchers focus on replacing current computer components with optical equivalents, resulting in an optical digital computer system processing binary data. Electronic transistor is the fundamental building block of modern electronic devices. To replace electronic components with optical ones, an equivalent optical transistor is required. Here we compare the behavior of an optical transistor with the reflection from a photonic band gap structure in an electromagnetically induced transparency medium. A control signal is used to modulate the photonic band gap structure. Power variation of the control signal is used to provide an analogy between the reflection behavior caused by modulating the photonic band gap structure and the shifting of Q-point (Operation point) as well as amplification function of optical transistor. By means of the control signal, the switching function of optical transistor has also been realized. Such experimental schemes could have potential applications in making optical diode and optical transistor used in quantum information processing.

  6. Analogy of transistor function with modulating photonic band gap in electromagnetically induced grating

    NASA Astrophysics Data System (ADS)

    Wang, Zhiguo; Ullah, Zakir; Gao, Mengqin; Zhang, Dan; Zhang, Yiqi; Gao, Hong; Zhang, Yanpeng

    2015-09-01

    Optical transistor is a device used to amplify and switch optical signals. Many researchers focus on replacing current computer components with optical equivalents, resulting in an optical digital computer system processing binary data. Electronic transistor is the fundamental building block of modern electronic devices. To replace electronic components with optical ones, an equivalent optical transistor is required. Here we compare the behavior of an optical transistor with the reflection from a photonic band gap structure in an electromagnetically induced transparency medium. A control signal is used to modulate the photonic band gap structure. Power variation of the control signal is used to provide an analogy between the reflection behavior caused by modulating the photonic band gap structure and the shifting of Q-point (Operation point) as well as amplification function of optical transistor. By means of the control signal, the switching function of optical transistor has also been realized. Such experimental schemes could have potential applications in making optical diode and optical transistor used in quantum information processing.

  7. Analogy of transistor function with modulating photonic band gap in electromagnetically induced grating

    PubMed Central

    Wang, Zhiguo; Ullah, Zakir; Gao, Mengqin; Zhang, Dan; Zhang, Yiqi; Gao, Hong; Zhang, Yanpeng

    2015-01-01

    Optical transistor is a device used to amplify and switch optical signals. Many researchers focus on replacing current computer components with optical equivalents, resulting in an optical digital computer system processing binary data. Electronic transistor is the fundamental building block of modern electronic devices. To replace electronic components with optical ones, an equivalent optical transistor is required. Here we compare the behavior of an optical transistor with the reflection from a photonic band gap structure in an electromagnetically induced transparency medium. A control signal is used to modulate the photonic band gap structure. Power variation of the control signal is used to provide an analogy between the reflection behavior caused by modulating the photonic band gap structure and the shifting of Q-point (Operation point) as well as amplification function of optical transistor. By means of the control signal, the switching function of optical transistor has also been realized. Such experimental schemes could have potential applications in making optical diode and optical transistor used in quantum information processing. PMID:26349444

  8. Absolute measurements of the electronic transition moments of seven band systems of the C2 molecule. Ph.D. Thesis - York Univ., Toronto

    NASA Technical Reports Server (NTRS)

    Cooper, D. M.

    1979-01-01

    Electronic transition moments of seven C2 singlet and triplet band systems in the 0.2-1.2 micron spectral region were measured. The measurements were made in emission behind incident shock waves in C2H2-argon mixtures. Narrow bandpass radiometers were used to obtain absolute measurements of shock-excited C2 radiation from which absolute electronic transition moments are derived by a synthetic spectrum analysis. New results are reported for the Ballik-Ramsay, Phillips, Swan, Deslandres-d'Azambuja, Fox-Herzberg, Mulliken, and Freymark systems.

  9. Inverse dispersion method for calculation of complex photonic band diagram and PT symmetry

    NASA Astrophysics Data System (ADS)

    Rybin, Mikhail V.; Limonov, Mikhail F.

    2016-04-01

    We suggest an inverse dispersion method for calculating a photonic band diagram for materials with arbitrary frequency-dependent dielectric functions. The method is able to calculate the complex wave vector for a given frequency by solving the eigenvalue problem with a non-Hermitian operator. The analogy with PT -symmetric Hamiltonians reveals that the operator corresponds to the momentum as a physical quantity, and the singularities at the band edges are related to the branch points and responses for the features on the band edges. The method is realized using a plane wave expansion technique for a two-dimensional periodic structure in the case of TE and TM polarizations. We illustrate the applicability of the method by the calculation of the photonic band diagrams of an infinite two-dimensional square lattice composed of dielectric cylinders using the measured frequency-dependent dielectric functions of different materials (amorphous hydrogenated carbon, silicon, and chalcogenide glass). We show that the method allows one to distinguish unambiguously between Bragg and Mie gaps in the spectra.

  10. Hydrogen production by Tuning the Photonic Band Gap with the Electronic Band Gap of TiO2

    PubMed Central

    Waterhouse, G. I. N.; Wahab, A. K.; Al-Oufi, M.; Jovic, V.; Anjum, D. H.; Sun-Waterhouse, D.; Llorca, J.; Idriss, H.

    2013-01-01

    Tuning the photonic band gap (PBG) to the electronic band gap (EBG) of Au/TiO2 catalysts resulted in considerable enhancement of the photocatalytic water splitting to hydrogen under direct sunlight. Au/TiO2 (PBG-357 nm) photocatalyst exhibited superior photocatalytic performance under both UV and sunlight compared to the Au/TiO2 (PBG-585 nm) photocatalyst and both are higher than Au/TiO2 without the 3 dimensionally ordered macro-porous structure materials. The very high photocatalytic activity is attributed to suppression of a fraction of electron-hole recombination route due to the co-incidence of the PBG with the EBG of TiO2 These materials that maintain their activity with very small amount of sacrificial agents (down to 0.5 vol.% of ethanol) are poised to find direct applications because of their high activity, low cost of the process, simplicity and stability. PMID:24108361

  11. Photonic DPASK/QAM signal generation at microwave/millimeter-wave band based on an electro-optic phase modulator.

    PubMed

    Zhang, Ye; Xu, Kun; Zhu, Ran; Li, Jianqiang; Wu, Jian; Hong, Xiaobin; Lin, Jintong

    2008-10-15

    We have proposed and experimentally demonstrated two novel photonic architectures to generate differential-phase amplitude-shift keying and circular quadrature amplitude modulation signals at microwave/millimeter-wave band based on an electro-optic phase modulator. In our proposed schemes, the electronic driven circuits were greatly simplified by employing the photonic vector modulation technique.

  12. Investigation of anisotropic photonic band gaps in three-dimensional magnetized plasma photonic crystals containing the uniaxial material

    SciTech Connect

    Zhang, Hai-Feng; Liu, Shao-Bin; Kong, Xiang-Kun

    2013-09-15

    In this paper, the dispersive properties of three-dimensional (3D) magnetized plasma photonic crystals (MPPCs) composed of anisotropic dielectric (the uniaxial material) spheres immersed in homogeneous magnetized plasma background with face-centered-cubic (fcc) lattices are theoretically investigated by the plane wave expansion method, as the Voigt effects of magnetized plasma are considered. The equations for calculating the anisotropic photonic band gaps (PBGs) in the first irreducible Brillouin zone are theoretically deduced. The anisotropic PBGs and two flatbands regions can be obtained. The effects of the ordinary-refractive index, extraordinary-refractive index, filling factor, plasma frequency, and external magnetic field on the dispersive properties of the 3D MPPCs are investigated in detail, respectively, and some corresponding physical explanations are also given. The numerical results show that the anisotropy can open partial band gaps in 3D MPPCs with fcc lattices and the complete PBGs can be found compared to the conventional 3D MPPCs doped by the isotropic material. The bandwidths of PBGs can be tuned by introducing the magnetized plasma into 3D PCs containing the uniaxial material. It is also shown that the anisotropic PBGs can be manipulated by the ordinary-refractive index, extraordinary-refractive index, filling factor, plasma frequency, and external magnetic field, respectively. The locations of flatbands regions cannot be manipulated by any parameters except for the plasma frequency and external magnetic field. Introducing the uniaxial material can obtain the complete PBGs as the 3D MPPCs with high symmetry and also provides a way to design the tunable devices.

  13. Investigation of anisotropic photonic band gaps in three-dimensional magnetized plasma photonic crystals containing the uniaxial material

    NASA Astrophysics Data System (ADS)

    Zhang, Hai-Feng; Liu, Shao-Bin; Kong, Xiang-Kun

    2013-09-01

    In this paper, the dispersive properties of three-dimensional (3D) magnetized plasma photonic crystals (MPPCs) composed of anisotropic dielectric (the uniaxial material) spheres immersed in homogeneous magnetized plasma background with face-centered-cubic (fcc) lattices are theoretically investigated by the plane wave expansion method, as the Voigt effects of magnetized plasma are considered. The equations for calculating the anisotropic photonic band gaps (PBGs) in the first irreducible Brillouin zone are theoretically deduced. The anisotropic PBGs and two flatbands regions can be obtained. The effects of the ordinary-refractive index, extraordinary-refractive index, filling factor, plasma frequency, and external magnetic field on the dispersive properties of the 3D MPPCs are investigated in detail, respectively, and some corresponding physical explanations are also given. The numerical results show that the anisotropy can open partial band gaps in 3D MPPCs with fcc lattices and the complete PBGs can be found compared to the conventional 3D MPPCs doped by the isotropic material. The bandwidths of PBGs can be tuned by introducing the magnetized plasma into 3D PCs containing the uniaxial material. It is also shown that the anisotropic PBGs can be manipulated by the ordinary-refractive index, extraordinary-refractive index, filling factor, plasma frequency, and external magnetic field, respectively. The locations of flatbands regions cannot be manipulated by any parameters except for the plasma frequency and external magnetic field. Introducing the uniaxial material can obtain the complete PBGs as the 3D MPPCs with high symmetry and also provides a way to design the tunable devices.

  14. Analysis of photonic band gap in dispersive properties of tunable three-dimensional photonic crystals doped by magnetized plasma

    SciTech Connect

    Zhang HaiFeng; Liu Shaobin; Yang Huan; Kong Xiangkun

    2013-03-15

    In this paper, the magnetooptical effects in dispersive properties for two types of three-dimensional magnetized plasma photonic crystals (MPPCs) containing homogeneous dielectric and magnetized plasma with diamond lattices are theoretically investigated for electromagnetic (EM) wave based on plane wave expansion (PWE) method, as incidence EM wave vector is parallel to the external magnetic field. The equations for two types of MPPCs with diamond lattices (dielectric spheres immersed in magnetized plasma background or vice versa) are theoretically deduced. The influences of dielectric constant, plasma collision frequency, filling factor, the external magnetic field, and plasma frequency on the dispersive properties for both types of structures are studied in detail, respectively, and some corresponding physical explanations are also given. From the numerical results, it has been shown that the photonic band gaps (PBGs) for both types of MPPCs can be manipulated by plasma frequency, filling factor, the external magnetic field, and the relative dielectric constant of dielectric, respectively. Especially, the external magnetic field can enlarge the PBG for type-2 structure (plasma spheres immersed in dielectric background). However, the plasma collision frequency has no effect on the dispersive properties of two types of three-dimensional MPPCs. The locations of flatbands regions for both types of structures cannot be tuned by any parameters except for plasma frequency and the external magnetic field. The analytical results may be informative and of technical use to design the MPPCs devices.

  15. The properties of photonic band gaps for three-dimensional plasma photonic crystals in a diamond structure

    SciTech Connect

    Zhang Haifeng; Liu Shaobin; Kong Xiangkun, Chenchen; Bian Borui

    2013-04-15

    In this paper, the properties of photonic band gaps (PBGs) for two types of three-dimensional plasma photonic crystals (PPCs) composed of isotropic dielectric and unmagnetized plasma with diamond lattices are theoretically investigated for electromagnetic waves based on a modified plane wave expansion method. The equations for type-1 structure are theoretically deduced, which depend on the diamond lattices realization (dielectric spheres immersed in plasma background). The influences of dielectric constant of dielectric, plasma collision frequency, filling factor, and plasma frequency on PBGs are investigated, respectively, and some corresponding physical explanations and the possible methods to realize the three-dimensional PPCs in experiments are also given. From the numerical results, it has been shown that not only the locations but also the gap/midgap ratios of the PBGs for two types of PPCs can be tuned by plasma frequency, filling factor, and the relative dielectric constant, respectively. However, the plasma collision frequency has no effect on the frequency ranges and gap/midgap ratios of the PBGs for two types of PPCs.

  16. The properties of photonic band gaps for three-dimensional plasma photonic crystals in a diamond structure

    NASA Astrophysics Data System (ADS)

    Zhang, Hai-Feng; Liu, Shao-Bin; Kong, Xiang-Kun; Chen-Chen; Bian, Bo-Rui

    2013-04-01

    In this paper, the properties of photonic band gaps (PBGs) for two types of three-dimensional plasma photonic crystals (PPCs) composed of isotropic dielectric and unmagnetized plasma with diamond lattices are theoretically investigated for electromagnetic waves based on a modified plane wave expansion method. The equations for type-1 structure are theoretically deduced, which depend on the diamond lattices realization (dielectric spheres immersed in plasma background). The influences of dielectric constant of dielectric, plasma collision frequency, filling factor, and plasma frequency on PBGs are investigated, respectively, and some corresponding physical explanations and the possible methods to realize the three-dimensional PPCs in experiments are also given. From the numerical results, it has been shown that not only the locations but also the gap/midgap ratios of the PBGs for two types of PPCs can be tuned by plasma frequency, filling factor, and the relative dielectric constant, respectively. However, the plasma collision frequency has no effect on the frequency ranges and gap/midgap ratios of the PBGs for two types of PPCs.

  17. Analysis of photonic band gap in dispersive properties of tunable three-dimensional photonic crystals doped by magnetized plasma

    NASA Astrophysics Data System (ADS)

    Zhang, Hai-Feng; Liu, Shao-Bin; Yang, Huan; Kong, Xiang-Kun

    2013-03-01

    In this paper, the magnetooptical effects in dispersive properties for two types of three-dimensional magnetized plasma photonic crystals (MPPCs) containing homogeneous dielectric and magnetized plasma with diamond lattices are theoretically investigated for electromagnetic (EM) wave based on plane wave expansion (PWE) method, as incidence EM wave vector is parallel to the external magnetic field. The equations for two types of MPPCs with diamond lattices (dielectric spheres immersed in magnetized plasma background or vice versa) are theoretically deduced. The influences of dielectric constant, plasma collision frequency, filling factor, the external magnetic field, and plasma frequency on the dispersive properties for both types of structures are studied in detail, respectively, and some corresponding physical explanations are also given. From the numerical results, it has been shown that the photonic band gaps (PBGs) for both types of MPPCs can be manipulated by plasma frequency, filling factor, the external magnetic field, and the relative dielectric constant of dielectric, respectively. Especially, the external magnetic field can enlarge the PBG for type-2 structure (plasma spheres immersed in dielectric background). However, the plasma collision frequency has no effect on the dispersive properties of two types of three-dimensional MPPCs. The locations of flatbands regions for both types of structures cannot be tuned by any parameters except for plasma frequency and the external magnetic field. The analytical results may be informative and of technical use to design the MPPCs devices.

  18. Absolute intensities for the Q-branch of the 3 nu(sub 2) (-) nu(sub 1) (465.161/cm) band of nitrous oxide

    NASA Technical Reports Server (NTRS)

    Sirota, J. Marcos; Reuter, Dennis C.

    1993-01-01

    The absolute intensities of four lines, Q 15-Q 18 in the 03(sup 1)0-10(sup 0)0 band, of N2O have been measured using a tunable diode laser spectrometer at temperatures between 380 and 420 K and pressures between 4 and 15 torr. Even though these transitions are weak and produced only about 2% of absorption at the line center for a pathlength of 52 m, they were measured with a signal to noise ratio of about 20 due to the high sensitivity of the instrument. The band strength derived is 1.03 x 10(exp -24) cm/molec at 296 K.

  19. Efficient heralding of O-band passively spatial-multiplexed photons for noise-tolerant quantum key distribution.

    PubMed

    Liu, Mao Tong; Lim, Han Chuen

    2014-09-22

    When implementing O-band quantum key distribution on optical fiber transmission lines carrying C-band data traffic, noise photons that arise from spontaneous Raman scattering or insufficient filtering of the classical data channels could cause the quantum bit-error rate to exceed the security threshold. In this case, a photon heralding scheme may be used to reject the uncorrelated noise photons in order to restore the quantum bit-error rate to a low level. However, the secure key rate would suffer unless one uses a heralded photon source with sufficiently high heralding rate and heralding efficiency. In this work we demonstrate a heralded photon source that has a heralding efficiency that is as high as 74.5%. One disadvantage of a typical heralded photon source is that the long deadtime of the heralding detector results in a significant drop in the heralding rate. To counter this problem, we propose a passively spatial-multiplexed configuration at the heralding arm. Using two heralding detectors in this configuration, we obtain an increase in the heralding rate by 37% and a corresponding increase in the heralded photon detection rate by 16%. We transmit the O-band photons over 10 km of noisy optical fiber to observe the relation between quantum bit-error rate and noise-degraded second-order correlation function of the transmitted photons. The effects of afterpulsing when we shorten the deadtime of the heralding detectors are also observed and discussed.

  20. Robust topology optimization of three-dimensional photonic-crystal band-gap structures.

    PubMed

    Men, H; Lee, K Y K; Freund, R M; Peraire, J; Johnson, S G

    2014-09-22

    We perform full 3D topology optimization (in which "every voxel" of the unit cell is a degree of freedom) of photonic-crystal structures in order to find optimal omnidirectional band gaps for various symmetry groups, including fcc (including diamond), bcc, and simple-cubic lattices. Even without imposing the constraints of any fabrication process, the resulting optimal gaps are only slightly larger than previous hand designs, suggesting that current photonic crystals are nearly optimal in this respect. However, optimization can discover new structures, e.g. a new fcc structure with the same symmetry but slightly larger gap than the well known inverse opal, which may offer new degrees of freedom to future fabrication technologies. Furthermore, our band-gap optimization is an illustration of a computational approach to 3D dispersion engineering which is applicable to many other problems in optics, based on a novel semidefinite-program formulation for nonconvex eigenvalue optimization combined with other techniques such as a simple approach to impose symmetry constraints. We also demonstrate a technique for robust topology optimization, in which some uncertainty is included in each voxel and we optimize the worst-case gap, and we show that the resulting band gaps have increased robustness to systematic fabrication errors. PMID:25321732

  1. Micro-metric electronic patterning of a topological band structure using a photon beam

    NASA Astrophysics Data System (ADS)

    Golden, Mark; Frantzeskakis, Emmanouil; de Jong, Nick; Huang, Yingkai; Wu, Dong; Pan, Yu; de Visser, Anne; van Heumen, Erik; van Bay, Tran; Zwartsenberg, Berend; Pronk, Pieter; Varier Ramankutty, Shyama; Tytarenko, Alona; Xu, Nan; Plumb, Nick; Shi, Ming; Radovic, Milan; Varkhalov, Andrei

    2015-03-01

    The only states crossing EF in ideal, 3D TIs are topological surface states. Single crystals of Bi2Se3andBi2Te3 are too defective to exhibit bulk-insulating behaviour, and ARPES shows topologically trivial 2DEGs at EF in the surface region due to downward band bending. Ternary & quaternary alloys of Bi /Te /Se /Sb hold promise for obtaining bulk-insulating crystals. Here we report ARPES data from quaternary, bulk-insulating, Bi-based TIs. Shortly after cleavage in UHV, downward band bending pulls the bulk conduction band below EF, once again frustrating the ``topological only'' ambition for the Fermi surface. However, there is light at the end of the tunnel: we show that a super-band-gap photon beam generates a surface photovoltage sufficient to flatten the bands, thereby recovering the ideal, ``topological only'' situation. In our bulk-insulating quaternary TIs, this effect is local in nature, and permits the writing of arbitrary, micron-sized patterns in the topological energy landscape at the surface. Support from FOM, NWO and the EU is gratefully acknowledged.

  2. Acousto-optic modulation of a photonic crystal nanocavity with Lamb waves in microwave K band

    SciTech Connect

    Tadesse, Semere A.; Li, Huan; Liu, Qiyu; Li, Mo

    2015-11-16

    Integrating nanoscale electromechanical transducers and nanophotonic devices potentially can enable acousto-optic devices to reach unprecedented high frequencies and modulation efficiency. Here, we demonstrate acousto-optic modulation of a photonic crystal nanocavity using Lamb waves with frequency up to 19 GHz, reaching the microwave K band. The devices are fabricated in suspended aluminum nitride membrane. Excitation of acoustic waves is achieved with interdigital transducers with period as small as 300 nm. Confining both acoustic wave and optical wave within the thickness of the membrane leads to improved acousto-optic modulation efficiency in these devices than that obtained in previous surface acoustic wave devices. Our system demonstrates a scalable optomechanical platform where strong acousto-optic coupling between cavity-confined photons and high frequency traveling phonons can be explored.

  3. Photonic band gap characteristics of one-dimensional graphene-dielectric periodic structures

    NASA Astrophysics Data System (ADS)

    Al-sheqefi, F. U. Y.; Belhadj, W.

    2015-12-01

    In this paper, we study theoretically, the transmission properties of a one-dimensional graphene-dielectric periodic structure by using the transfer matrix method. Within the framework of this method, we confirm earlier finding that a periodic structure composed of a stack of monolayer graphene sheets separated by dielectric slabs, possesses photonic band-gap (PBG) properties and supports a series of bandpass and band-stop regions at low-terahertz frequencies. Our calculations showed that the suggested structure possesses in addition to the structural Bragg gaps, a new type of band gap that exhibits a rather versatile behavior with varying angle of incidence. We find this type of band gap is omnidirectional (omni-gap) for both transverse electric (TE) and transverse magnetic (TM) polarizations. Our results show that 1D graphene-dielectric periodic structures are very good candidates for band gap engineering. Specifically, we demonstrate the existence of a band gap region for both polarizations which survives for incident angles as high as 80°. Moreover, we show how our proposed structure can also function as a highly efficient polarization splitter. It is also found that the band gaps can be tuned by tuning the properties of the graphene via a gate voltage. In order to investigate difference between the omni-gap and Bragg PBG, we plot the electromagnetic field profiles for some critical frequencies. The proposed structure is promising and can work as a gate tunable perfect stop filter which completely blocks both polarizations, and may have many other potential applications.

  4. Numerical investigation of the flat band Bloch modes in a 2D photonic crystal with Dirac cones.

    PubMed

    Zhang, Peng; Fietz, Chris; Tassin, Philippe; Koschny, Thomas; Soukoulis, Costas M

    2015-04-20

    A numerical method combining complex-k band calculations and absorbing boundary conditions for Bloch waves is presented. We use this method to study photonic crystals with Dirac cones. We demonstrate that the photonic crystal behaves as a zero-index medium when excited at normal incidence, but that the zero-index behavior is lost at oblique incidence due to excitation of modes on the flat band. We also investigate the formation of monomodal and multimodal cavity resonances inside the photonic crystals, and the physical origins of their different line-shape features.

  5. Analysis of band structure, transmission properties, and dispersion behavior of THz wave in one-dimensional parabolic plasma photonic crystal

    SciTech Connect

    Askari, Nasim; Eslami, Esmaeil; Mirzaie, Reza

    2015-11-15

    The photonic band gap of obliquely incident terahertz electromagnetic waves in a one-dimensional plasma photonic crystal is studied. The periodic structure consists of lossless dielectric and inhomogeneous plasma with a parabolic density profile. The dispersion relation and the THz wave transmittance are analyzed based on the electromagnetic equations and transfer matrix method. The dependence of effective plasma frequency and photonic band gap characteristics on dielectric and plasma thickness, plasma density, and incident angle are discussed in detail. A theoretical calculation for effective plasma frequency is presented and compared with numerical results. Results of these two methods are in good agreement.

  6. Applicability of effective medium description to photonic crystals in higher bands: Theory and numerical analysis

    NASA Astrophysics Data System (ADS)

    Markel, Vadim A.; Tsukerman, Igor

    2016-06-01

    We consider conditions under which photonic crystals (PCs) can be homogenized in the higher photonic bands and, in particular, near the Γ point. By homogenization we mean introducing some effective local parameters ɛeff and μeff that describe reflection, refraction, and propagation of electromagnetic waves in the PC adequately. The parameters ɛeff and μeff can be associated with a hypothetical homogeneous effective medium. In particular, if the PC is homogenizable, the dispersion relations and isofrequency lines in the effective medium and in the PC should coincide to some level of approximation. We can view this requirement as a necessary condition of homogenizability. In the vicinity of a Γ point, real isofrequency lines of two-dimensional PCs can be close to mathematical circles, just like in the case of isotropic homogeneous materials. Thus, one may be tempted to conclude that introduction of an effective medium is possible and, at least, the necessary condition of homogenizability holds in this case. We, however, show that this conclusion is incorrect: complex dispersion points must be included into consideration even in the case of strictly nonabsorbing materials. By analyzing the complex dispersion relations and the corresponding isofrequency lines, we have found that two-dimensional PCs with C4 and C6 symmetries are not homogenizable in the higher photonic bands. We also draw a distinction between spurious Γ -point frequencies that are due to Brillouin-zone folding of Bloch bands and "true" Γ -point frequencies that are due to multiple scattering. Understanding of the physically different phenomena that lead to the appearance of spurious and "true" Γ -point frequencies is important for the theory of homogenization.

  7. Exceptional Contours and Band Structure Design in Parity-Time Symmetric Photonic Crystals.

    PubMed

    Cerjan, Alexander; Raman, Aaswath; Fan, Shanhui

    2016-05-20

    We investigate the properties of two-dimensional parity-time symmetric periodic systems whose non-Hermitian periodicity is an integer multiple of the underlying Hermitian system's periodicity. This creates a natural set of degeneracies that can undergo thresholdless PT transitions. We derive a k·p perturbation theory suited to the continuous eigenvalues of such systems in terms of the modes of the underlying Hermitian system. In photonic crystals, such thresholdless PT transitions are shown to yield significant control over the band structure of the system, and can result in all-angle supercollimation, a PT-superprism effect, and unidirectional behavior.

  8. Design and testing of photonic band gap channel-drop-filters

    SciTech Connect

    Shchegolkov, Dmitry; Earley, Lawrence M; Health, Cynthia E; Smirnova, Evgenya I

    2009-01-01

    We have designed, fabricated and tested several novel passive mm-wave spectrometers based on Photonic Band Gap (PBG) structures. Our spectrometers were designed to operate in the frequency ranges of 90-130 and 220-300 GHz. We built and tested both metallic and dielectric silicon Channel-Drop-Filter (CDF) structures at 90-130 GHz. We are currently fabricating a dielectric CDF structure to operate at 220-300 GHz. The complete recent test results for the metal version and preliminary test results for the higher frequency silicon versions will be presented at the conference.

  9. Observation of the four wave mixing photonic band gap signal in electromagnetically induced grating.

    PubMed

    Ullah, Zakir; Wang, Zhiguo; Gao, Mengqin; Zhang, Dan; Zhang, Yiqi; Gao, Hong; Zhang, Yanpeng

    2014-12-01

    For the first time, we experimentally and theoretically research about the probe transmission signal (PTS), the reflected four wave mixing band gap signal(FWM BGS) and fluorescence signal (FLS) under the double dressing effect in an inverted Y-type four level system. FWM BGS results from photonic band gap structure. We demonstrate that the characteristics of PTS, FWM BGS and FLS can be controlled by power, phase and the frequency detuning of the dressing beams. It is observed in our experiment that FWM BGS switches from suppression to enhancement, corresponding to the switch from transmission enhancement to absorption enhancement in the PTS with changing the relative phase. We also observe the relation among the three signals, which satisfy the law of conservation of energy. Such scheme could have potential applications in optical diodes, amplifiers and quantum information processing.

  10. Research of dual-band microwave photonic filter for WLAN based on optical frequency comb.

    PubMed

    Zhang, Qi; Li, Jiaqi; Jiang, Lingke; Pan, Linbing; Dong, Wei; Zhang, Xindong; Ruan, Shengping

    2016-07-20

    This paper presents a dual-band microwave photonic filter for a wireless local area networks with independently tunable passband center frequencies and bandwidths. The two bands of the filter were 2.4 GHz and 5.725 GHz, respectively. The filter was based on a stimulated Brillouin scattering and an optical frequency comb (OFC) scheme. We created this filter using OFC pumps instead of a single pump. The OFC scheme consists of a cascaded Mach-Zehnder modulator (MZM) and a dual-parallel MZM (DPMZM) hybrid modulation that generated seven and 11 lines. The experimental results show that the two passbands of the filter were 80 and 130 MHz. PMID:27463899

  11. Observation of wakefields in a beam-driven photonic band gap accelerating structure.

    SciTech Connect

    Conde, M.; Yusof, Z.; Power, J. G.; Jing, C.; Gao, F.; Antipov, S.; Xu, P.; Zheng, S.; Chen, H.; Tang, C.; Gai, W.; High Energy Physics; Euclid Techlabs LLC; Tsinghua Univ.

    2009-12-01

    Wakefield excitation has been experimentally studied in a three-cell X-band standing wave photonic band gap (PBG) accelerating structure. Major monopole (TM{sub 01}- and TM{sub 02}-like) and dipole (TM{sub 11}- and TM{sub 12}-like) modes were identified and characterized by precisely controlling the position of beam injection. The quality factor Q of the dipole modes was measured to be {approx}10 times smaller than that of the accelerating mode. A charge sweep, up to 80 nC, has been performed, equivalent to {approx} 30 MV/m accelerating field on axis. A variable delay low charge witness bunch following a high charge drive bunch was used to calibrate the gradient in the PBG structure by measuring its maximum energy gain and loss. Experimental results agree well with numerical simulations.

  12. Band-edge lasing and miniband lasing in 1-D dual-periodic photonic crystal

    NASA Astrophysics Data System (ADS)

    Ying, Cui-Feng; Zhou, Wen-Yuan; Li, Yi; Ye, Qing; Zhang, Chun-Ping; Tian, Jian-Guo

    2012-06-01

    Herein, we report two different dual-periodic Photonic Crystals (PCs) in dichromated gelatin emulsion which are fabricated by four-beam holography and double-exposure holography. The minibands with high Q-factors have been evidently located in both two structures. By taking into account the non-uniform distribution of material, the numerical results agree quite well with the experimental results. We also compared the band-edge lasing in single-periodic PC and miniband lasing in Moiré dual-periodic PC. Due to extremely flat dispersion and large mode volume of the miniband, high optical conversion efficiency in miniband lasing is achieved as compared with that of band-edge lasing. Such effect may provide potential applications in low-threshold lasers and ultra-sensitive fluorescent probes in biological assays.

  13. Nonlinear optical response of semiconductor-nanocrystals-embedded photonic band gap structure

    SciTech Connect

    Liao, Chen; Zhang, Huichao; Tang, Luping; Zhou, Zhiqiang; Lv, Changgui; Cui, Yiping; Zhang, Jiayu

    2014-04-28

    Colloidal CdSe/ZnS core/shell nanocrystals (NCs), which were dispersed in SiO{sub 2} sol, were utilized to fabricate a SiO{sub 2}:NCs/TiO{sub 2} all-dielectric photonic band gap (PBG) structure. The third-order nonlinear refractive index (n{sub 2}) of the PBG structure was nearly triple of that of the SiO{sub 2}:NCs film due to the local field enhancement in the PBG structure. The photoinduced change in refractive index (Δn) could shift the PBG band edge, so the PBG structure would show significant transmission modification, whose transmission change was ∼17 folds of that of the SiO{sub 2}:NCs film. Under excitation of a 30 GW/cm{sup 2} femtosecond laser beam, a transmission decrease of 80% was realized.

  14. Role of Short-Range Order and Hyperuniformity in the Formation of Band Gaps in Disordered Photonic Materials

    NASA Astrophysics Data System (ADS)

    Froufe-Pérez, Luis S.; Engel, Michael; Damasceno, Pablo F.; Muller, Nicolas; Haberko, Jakub; Glotzer, Sharon C.; Scheffold, Frank

    2016-07-01

    We study photonic band gap formation in two-dimensional high-refractive-index disordered materials where the dielectric structure is derived from packing disks in real and reciprocal space. Numerical calculations of the photonic density of states demonstrate the presence of a band gap for all polarizations in both cases. We find that the band gap width is controlled by the increase in positional correlation inducing short-range order and hyperuniformity concurrently. Our findings suggest that the optimization of short-range order, in particular the tailoring of Bragg scattering at the isotropic Brillouin zone, are of key importance for designing disordered PBG materials.

  15. Spectral and polarization structure of field-induced photonic bands in cholesteric liquid crystals

    NASA Astrophysics Data System (ADS)

    Palto, S. P.; Barnik, M. I.; Geivandov, A. R.; Kasyanova, I. V.; Palto, V. S.

    2015-09-01

    Transmission of planar layers of cholesteric liquid crystals is studied in pulsed electric fields perpendicular to the helix axis at normal incidence of both linearly polarized and unpolarized light. Spectral and light polarization properties of the primary photonic band and the field-induced bands up to fourth order of Bragg selective reflection are studied in detail. In our experiments we have achieved an electric field strength several times higher than the theoretical values corresponding to the critical field of full helix unwinding. However, the experiments show that despite the high strength of the electric field applied the helix does not unwind, but strongly deforms, keeping its initial spatial period. Strong helix deformation results in distinct spectral band splitting, as well as very high field-induced selective reflectance that can be applied in lasers and other optoelectronic devices. Peculiarities of inducing and splitting the bands are discussed in terms of the scattering coefficient approach. All observed effects are confirmed by numerical simulations. The simulations also show that liquid crystal surface anchoring is not the factor that prevents the helix unwinding. Thus, the currently acknowledged concept of continuous helix unwinding in the electric field should be reconsidered.

  16. Periodic dielectric structure for production of photonic band gap and devices incorporating the same

    DOEpatents

    Ho, Kai-Ming; Chan, Che-Ting; Soukoulis, Costas

    1994-08-02

    A periodic dielectric structure which is capable of producing a photonic band gap and which is capable of practical construction. The periodic structure is formed of a plurality of layers, each layer being formed of a plurality of rods separated by a given spacing. The material of the rods contrasts with the material between the rods to have a refractive index contrast of at least two. The rods in each layer are arranged with their axes parallel and at a given spacing. Adjacent layers are rotated by 90.degree., such that the axes of the rods in any given layer are perpendicular to the axes in its neighbor. Alternating layers (that is, successive layers of rods having their axes parallel such as the first and third layers) are offset such that the rods of one are about at the midpoint between the rods of the other. A four-layer periocity is thus produced, and successive layers are stacked to form a three-dimensional structure which exhibits a photonic band gap. By virtue of forming the device in layers of elongate members, it is found that the device is susceptible of practical construction.

  17. Self-induced transparency solitary waves in a doped nonlinear photonic band gap material

    NASA Astrophysics Data System (ADS)

    Aközbek, Neşet; John, Sajeev

    1998-09-01

    We derive the properties of self-induced transparency (SIT) solitary waves in a one-dimensional periodic structure doped uniformly with resonance two-level atoms. In our model, the electromagnetic field is treated classically and the dopant atoms are described quantum mechanically. The resulting solitary waves take the form of ultrashort (picosecond) laser pulses which propagate near the band edge of the nonlinear photonic band gap (PBG) material doped with rare-earth atoms such as erbium. Solitary wave formation involves the combined effects of group velocity dispersion (GVD), nonresonant Kerr nonlinearity, and resonant interaction with dopant atoms. We derive the general Maxwell-Bloch equations for a nonlinear PBG system and then demonstrate the existence of elementary solitary wave solutions for frequencies far outside the gap where GVD effects are negligible and for frequencies near the photonic band edge where GVD effects are crucial. We find two distinct new types of propagating SIT solitary wave pulses. Far from Bragg resonance, we recapture the usual McCall-Hahn soliton with hyperbolic secant profile when the nonlinear Kerr coefficient χ(3)=0. However, when the host nonresonant Kerr coefficient is nonzero, we obtain the first new type of soliton. In this case, the optical soliton envelope function deviates from the hyperbolic secant profile and pulse propagation requires nontrivial phase modulation (chirping). We derive the dependence of the solitary wave structure on the Kerr coefficient χ(3), the resonance impurity atom density, and the detuning of the average laser frequency from the atomic transition. When the laser frequency and the atomic transition frequencies are near the photonic band edge we obtain the second type of soliton. To illustrate the second type of soliton we consider two special cases. In the first case, GVD facilitates the propagation of an unchirped SIT-gap soliton moving at a velocity fixed by the material's parameters. The soliton

  18. Experimental Demonstration of a Hybrid-Quantum-Emitter Producing Individual Entangled Photon Pairs in the Telecom Band.

    PubMed

    Chen, Geng; Zou, Yang; Zhang, Wen-Hao; Zhang, Zi-Huai; Zhou, Zong-Quan; He, De-Yong; Tang, Jian-Shun; Liu, Bi-Heng; Yu, Ying; Zha, Guo-Wei; Ni, Hai-Qiao; Niu, Zhi-Chuan; Han, Yong-Jian; Li, Chuan-Feng; Guo, Guang-Can

    2016-01-01

    Quantum emitters generating individual entangled photon pairs (IEPP) have significant fundamental advantages over schemes that suffer from multiple photon emission, or schemes that require post-selection techniques or the use of photon-number discriminating detectors. Quantum dots embedded within nanowires (QD-NWs) represent one of the most promising candidate for quantum emitters that provide a high collection efficiency of photons. However, a quantum emitter that generates IEPP in the telecom band is still an issue demanding a prompt solution. Here, we demonstrate in principle that IEPPs in the telecom band can be created by combining a single QD-NW and a nonlinear crystal waveguide. The QD-NW system serves as the single photon source, and the emitted visible single photons are split into IEPPs at approximately 1.55 μm through the process of spontaneous parametric down conversion (SPDC) in a periodically poled lithium niobate (PPLN) waveguide. The compatibility of the QD-PPLN interface is the determinant factor in constructing this novel hybrid-quantum-emitter (HQE). Benefiting from the desirable optical properties of QD-NWs and the extremely high nonlinear conversion efficiency of PPLN waveguides, we successfully generate IEPPs in the telecom band with the polarization degree of freedom. The entanglement of the generated photon pairs is confirmed by the entanglement witness. Our experiment paves the way to producing HQEs inheriting the advantages of multiple systems. PMID:27225881

  19. Experimental Demonstration of a Hybrid-Quantum-Emitter Producing Individual Entangled Photon Pairs in the Telecom Band

    PubMed Central

    Chen, Geng; Zou, Yang; Zhang, Wen-Hao; Zhang, Zi-Huai; Zhou, Zong-Quan; He, De-Yong; Tang, Jian-Shun; Liu, Bi-Heng; Yu, Ying; Zha, Guo-Wei; Ni, Hai-Qiao; Niu, Zhi-Chuan; Han, Yong-Jian; Li, Chuan-Feng; Guo, Guang-Can

    2016-01-01

    Quantum emitters generating individual entangled photon pairs (IEPP) have significant fundamental advantages over schemes that suffer from multiple photon emission, or schemes that require post-selection techniques or the use of photon-number discriminating detectors. Quantum dots embedded within nanowires (QD-NWs) represent one of the most promising candidate for quantum emitters that provide a high collection efficiency of photons. However, a quantum emitter that generates IEPP in the telecom band is still an issue demanding a prompt solution. Here, we demonstrate in principle that IEPPs in the telecom band can be created by combining a single QD-NW and a nonlinear crystal waveguide. The QD-NW system serves as the single photon source, and the emitted visible single photons are split into IEPPs at approximately 1.55 μm through the process of spontaneous parametric down conversion (SPDC) in a periodically poled lithium niobate (PPLN) waveguide. The compatibility of the QD-PPLN interface is the determinant factor in constructing this novel hybrid-quantum-emitter (HQE). Benefiting from the desirable optical properties of QD-NWs and the extremely high nonlinear conversion efficiency of PPLN waveguides, we successfully generate IEPPs in the telecom band with the polarization degree of freedom. The entanglement of the generated photon pairs is confirmed by the entanglement witness. Our experiment paves the way to producing HQEs inheriting the advantages of multiple systems. PMID:27225881

  20. Wave propagation in ordered, disordered, and nonlinear photonic band gap materials

    SciTech Connect

    Lidorikis, Elefterios

    1999-12-10

    Photonic band gap materials are artificial dielectric structures that give the promise of molding and controlling the flow of optical light the same way semiconductors mold and control the electric current flow. In this dissertation the author studied two areas of photonic band gap materials. The first area is focused on the properties of one-dimensional PBG materials doped with Kerr-type nonlinear material, while, the second area is focused on the mechanisms responsible for the gap formation as well as other properties of two-dimensional PBG materials. He first studied, in Chapter 2, the general adequacy of an approximate structure model in which the nonlinearity is assumed to be concentrated in equally-spaced very thin layers, or 6-functions, while the rest of the space is linear. This model had been used before, but its range of validity and the physical reasons for its limitations were not quite clear yet. He performed an extensive examination of many aspects of the model's nonlinear response and comparison against more realistic models with finite-width nonlinear layers, and found that the d-function model is quite adequate, capturing the essential features in the transmission characteristics. The author found one exception, coming from the deficiency of processing a rigid bottom band edge, i.e. the upper edge of the gaps is always independent of the refraction index contrast. This causes the model to miss-predict that there are no soliton solutions for a positive Kerr-coefficient, something known to be untrue.

  1. Semianalytical formulation on the scattering of proximity equilibration cell closed ring photonic band gap structures

    NASA Astrophysics Data System (ADS)

    Liu, Yunhong; Alexopoulos, Nicolaos G.

    2007-12-01

    A novel semianalytical methodology is used to analyze a periodic array of printed metallic closed ring elements in a multilayered dielectric structure. This approach is unique in that it is the first methodology capable in modeling structures with resonant implants and interelement dimensions well beyond the effective medium theory. In addition, it yields computational efficiency by 2 orders of magnitude over standard computational methods in computing the scattering parameters for proximity equilibration cell (PEC) closed ring multilayered (electromagnetic band gap and photonic band gap (PBG)) structures. Moreover, it provides physical insight in the implementation of metallic implants for practical applications. This methodology satisfies the Kramers-Kronig relations and causality, and therefore it allows for the development of semianalytical expressions for the composite's wave impedance, index of refraction, as well as the permittivity and permeability parameters accounting for full dispersion. For general artificial multilayered structures (PBG metamaterials) with centrosymmetric scattering matrices, the composite may be replaced by an equivalent homogeneous dispersive magneto-dielectric material and may be used for the design of integrated circuits, filters, and antennas using standard methods. Otherwise, use of the scattering matrix approach to obtain the effective parameters is valid only for semi-infinite structures. The upper band edge is determined by the host material uniquely and the bandwidth is determined by the shunt susceptance for different PEC ring inclusions.

  2. Design of full-k-space flat bands in photonic crystals beyond the tight-binding picture.

    PubMed

    Xu, Changqing; Wang, Gang; Hang, Zhi Hong; Luo, Jie; Chan, C T; Lai, Yun

    2015-12-11

    Based on a band engineering method, we propose a theoretical prescription to create a full-k-space flat band in dielectric photonic crystals covering the whole Brillouin Zone. With wave functions distributed in air instead of in the dielectrics, such a flat band represents a unique mechanism for achieving flat dispersions beyond the tight-binding picture, which can enormously reduce the requirement of permittivity contrast in the system. Finally, we propose and numerically demonstrate a unique application based on the full-k-space coverage of the flat band: ultra-sensitive detection of small scatterers.

  3. Design of full-k-space flat bands in photonic crystals beyond the tight-binding picture

    PubMed Central

    Xu, Changqing; Wang, Gang; Hang, Zhi Hong; Luo, Jie; Chan, C. T.; Lai, Yun

    2015-01-01

    Based on a band engineering method, we propose a theoretical prescription to create a full-k-space flat band in dielectric photonic crystals covering the whole Brillouin Zone. With wave functions distributed in air instead of in the dielectrics, such a flat band represents a unique mechanism for achieving flat dispersions beyond the tight-binding picture, which can enormously reduce the requirement of permittivity contrast in the system. Finally, we propose and numerically demonstrate a unique application based on the full-k-space coverage of the flat band: ultra-sensitive detection of small scatterers. PMID:26656882

  4. The Development of Layered Photonic Band Gap Structures Using a Micro-Transfer Molding Technique

    SciTech Connect

    Kevin Jerome Sutherland

    2001-06-27

    Over the last ten years, photonic band gap (PBG) theory and technology have become an important area of research because of the numerous possible applications ranging from high-efficiency laser diodes to optical circuitry. This research concentrates on reducing the length scale in the fabrication of layered photonic band gap structures and developing procedures to improve processing consistency. Various procedures and materials have been used in the fabrication of layered PBG structures. This research focused on an economical micro transfer molding approach to create the final PBG structure. A poly dimethylsiloxane (PDMS) rubber mold was created from a silicon substrate. It was filled with epoxy and built layer-by-layer to create a 3-D epoxy structure. This structure was infiltrated with nanoparticle titania or a titania sol-gel, then fired to remove the polymer mold, leaving a monolithic ceramic inverse of the epoxy structure. The final result was a lattice of titania rolds that resembles a face-centered tetragonal structure. The original intent of this research was to miniaturize this process to a bar size small enough to create a photonic band gap for wavelengths of visible electro-magnetic radiation. The factor limiting progress was the absence of a silicon master mold of small enough dimensions. The Iowa State Microelectronics Research Center fabricated samples with periodicities of 2.5 and 1.0 microns with the existing technology, but a sample was needed on the order of 0.3 microns or less. A 0.4 micron sample was received from Sandia National Laboratory, which was made through an electron beam lithography process, but it contained several defects. The results of the work are primarily from the 2.5 and 1.0 micron samples. Most of the work focused on changing processing variables in order to optimize the infiltration procedure for the best results. Several critical parameters were identified, ranging from the ambient conditions to the specifics of the

  5. Large-area 2D periodic crystalline silicon nanodome arrays on nanoimprinted glass exhibiting photonic band structure effects.

    PubMed

    Becker, C; Lockau, D; Sontheimer, T; Schubert-Bischoff, P; Rudigier-Voigt, E; Bockmeyer, M; Schmidt, F; Rech, B

    2012-04-01

    Two-dimensional silicon nanodome arrays are prepared on large areas up to 50 cm² exhibiting photonic band structure effects in the near-infrared and visible wavelength region by downscaling a recently developed fabrication method based on nanoimprint-patterned glass, high-rate electron-beam evaporation of silicon, self-organized solid phase crystallization and wet-chemical etching. The silicon nanodomes, arranged in square lattice geometry with 300 nm lattice constant, are optically characterized by angular resolved reflection measurements, allowing the partial determination of the photonic band structure. This experimentally determined band structure agrees well with the outcome of three-dimensional optical finite-element simulations. A 16% photonic bandgap is predicted for an optimized geometry of the silicon nanodome arrays. By variation of the duration of the selective etching step, the geometry as well as the optical properties of the periodic silicon nanodome arrays can be controlled systematically.

  6. Observation of Wakefield Suppression in a Photonic-Band-Gap Accelerator Structure

    DOE PAGES

    Simakov, Evgenya I.; Arsenyev, Sergey A.; Buechler, Cynthia E.; Edwards, Randall L.; Romero, William P.; Conde, Manoel; Ha, Gwanghui; Power, John G.; Wisniewski, Eric E.; Jing, Chunguang

    2016-02-10

    We report experimental observation of higher order mode (HOM) wakefield suppression in a room-temperature traveling-wave photonic band gap (PBG) accelerating structure at 11.700 GHz. It has been long recognized that PBG structures have potential for reducing long-range wakefields in accelerators. The first ever demonstration of acceleration in a room-temperature PBG structure was conducted in 2005. Since then, the importance of PBG accelerator research has been recognized by many institutions. However, the full experimental characterization of the wakefield spectrum and demonstration of wakefield suppression when the accelerating structure is excited by an electron beam has not been performed to date. Wemore » conducted an experiment at the Argonne Wakefield Accelerator (AWA) test facility and observed wakefields excited by a single high charge electron bunch when it passes through a PBG accelerator structure. Lastly, excellent HOM suppression properties of the PBG accelerator were demonstrated in the beam test.« less

  7. Pushing the Gradient Limitations of Superconducting Photonic Band Gap Structure Cells

    SciTech Connect

    Simakov, Evgenya I.; Haynes, William B.; Kurennoy, Sergey S.; Shchegolkov, Dmitry; O'Hara, James F.; Olivas, Eric R.

    2012-06-07

    Superconducting photonic band gap resonators present us with unique means to place higher order mode couples in an accelerating cavity and efficiently extract HOMs. An SRF PBG resonator with round rods was successfully tested at LANL demonstrating operation at 15 MV/m. Gradient in the SRF PBG resonator was limited by magnetic quench. To increase the quench threshold in PBG resonators one must design the new geometry with lower surface magnetic fields and preserve the resonator's effectiveness for HOM suppression. The main objective of this research is to push the limits for the high-gradient operation of SRF PBG cavities. A NCRF PBG cavity technology is established. The proof-of-principle operation of SRF PBG cavities is demonstrated. SRF PBG resonators are effective for outcoupling HOMs. PBG technology can significantly reduce the size of SRF accelerators and increase brightness for future FELs.

  8. Omnidirectional band gaps in quasiperiodic photonic crystals in the THz region

    NASA Astrophysics Data System (ADS)

    Araújo, C. A. A.; Vasconcelos, M. S.; Mauriz, P. W.; Albuquerque, E. L.

    2012-11-01

    In this work we calculate the emittance spectra of the electromagnetic radiation normally and obliquely incident (s- and p-polarized modes) on a one-dimensional multilayer quasiperiodic photonic structure made up by layered system of positive (SiO2) and negative (LiTaO3) refractive index materials organized in a quasiperiodic (Fibonacci-like) fashion. We model the negative refractive index material by an effective medium, whose electric permittivity ɛ(ω) is characterized by a phonon-polariton frequency dependent dielectric function, while for the magnetic permeability μ(ω) we have a Drude-like frequency-dependent function. The emittance spectra are determined by means of a well known theoretical model based on Kirchoff's second law, together with a transfer matrix formalism. Our results shows that the omnidirectional band gaps appear in the THz regime, in well defined frequency intervals independently of the electromagnetic radiation's polarized modes.

  9. Multiwavelength L-band fiber laser with bismuth-oxide EDF and photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Ramzia Salem, A. M.; Al-Mansoori, M. H.; Hizam, H.; Mohd Noor, S. B.; Abu Bakar, M. H.; Mahdi, M. A.

    2011-05-01

    A multiwavelength laser comb using a bismuth-based erbium-doped fiber and 50 m photonic crystal fiber is demonstrated in a ring cavity configuration. The fiber laser is solely pumped by a single 1455 nm Raman pump laser to exploit its higher power delivery compared to that of a single-mode laser diode pump. At 264 mW Raman pump power and 1 mW Brillouin pump power, 38 output channels in the L-band have been realized with an optical signal-to-noise ratio above 15 dB and a Stokes line spacing of 0.08 nm. The laser exhibits a tuning range of 12 nm and produces stable Stokes lines across the tuning range between Brillouin pump wavelengths of 1603 nm and 1615 nm.

  10. Structural Coloration of Colloidal Fiber by Photonic Band Gap and Resonant Mie Scattering.

    PubMed

    Yuan, Wei; Zhou, Ning; Shi, Lei; Zhang, Ke-Qin

    2015-07-01

    Because structural color is fadeless and dye-free, structurally colored materials have attracted great attention in a wide variety of research fields. In this work, we report the use of a novel structural coloration strategy applied to the fabrication of colorful colloidal fibers. The nanostructured fibers with tunable structural colors were massively produced by colloidal electrospinning. Experimental results and theoretical modeling reveal that the homogeneous and noniridescent structural colors of the electrospun fibers are caused by two phenomena: reflection due to the band gap of photonic structure and Mie scattering of the colloidal spheres. Our unprecedented findings show promise in paving way for the development of revolutionary dye-free technology for the coloration of various fibers. PMID:26066732

  11. High-power narrow-vertical-divergence photonic band crystal laser diodes with optimized epitaxial structure

    SciTech Connect

    Liu, Lei; Qu, Hongwei; Liu, Yun; Zhang, Yejin; Zheng, Wanhua; Wang, Yufei; Qi, Aiyi

    2014-12-08

    900 nm longitudinal photonic band crystal (PBC) laser diodes with optimized epitaxial structure are fabricated. With a same calculated fundamental-mode divergence, stronger mode discrimination is achieved by a quasi-periodic index modulation in the PBC waveguide than a periodic one. Experiments show that the introduction of over 5.5 μm-thick PBC waveguide contributes to only 10% increment of the internal loss for the laser diodes. For broad area PBC lasers, output powers of 5.75 W under continuous wave test and over 10 W under quasi-continuous wave test are reported. The vertical divergence angles are 10.5° at full width at half maximum and 21.3° with 95% power content, in conformity with the simulated angles. Such device shows a prospect for high-power narrow-vertical-divergence laser emission from single diode laser and laser bar.

  12. Experimental high gradient testing of a 17.1 GHz photonic band-gap accelerator structure

    NASA Astrophysics Data System (ADS)

    Munroe, Brian J.; Zhang, JieXi; Xu, Haoran; Shapiro, Michael A.; Temkin, Richard J.

    2016-03-01

    We report the design, fabrication, and high gradient testing of a 17.1 GHz photonic band-gap (PBG) accelerator structure. Photonic band-gap (PBG) structures are promising candidates for electron accelerators capable of high-gradient operation because they have the inherent damping of high order modes required to avoid beam breakup instabilities. The 17.1 GHz PBG structure tested was a single cell structure composed of a triangular array of round copper rods of radius 1.45 mm spaced by 8.05 mm. The test assembly consisted of the test PBG cell located between conventional (pillbox) input and output cells, with input power of up to 4 MW from a klystron supplied via a TM01 mode launcher. Breakdown at high gradient was observed by diagnostics including reflected power, downstream and upstream current monitors and visible light emission. The testing procedure was first benchmarked with a conventional disc-loaded waveguide structure, which reached a gradient of 87 MV /m at a breakdown probability of 1.19 ×10-1 per pulse per meter. The PBG structure was tested with 100 ns pulses at gradient levels of less than 90 MV /m in order to limit the surface temperature rise to 120 K. The PBG structure reached up to 89 MV /m at a breakdown probability of 1.09 ×10-1 per pulse per meter. These test results show that a PBG structure can simultaneously operate at high gradients and low breakdown probability, while also providing wakefield damping.

  13. Wide-band acousto-optic deflectors for large field of view two-photon microscope.

    PubMed

    Jiang, Runhua; Zhou, Zhenqiao; Lv, Xiaohua; Zeng, Shaoqun

    2012-04-01

    Acousto-optic deflector (AOD) is an attractive scanner for two-photon microscopy because it can provide fast and versatile laser scanning and does not involve any mechanical movements. However, due to the small scan range of available AOD, the field of view (FOV) of the AOD-based microscope is typically smaller than that of the conventional galvanometer-based microscope. Here, we developed a novel wide-band AOD to enlarge the scan angle. Considering the maximum acceptable acoustic attenuation in the acousto-optic crystal, relatively lower operating frequencies and moderate aperture were adopted. The custom AOD was able to provide 60 MHz 3-dB bandwidth and 80% peak diffraction efficiency at 840 nm wavelength. Based on a pair of such AOD, a large FOV two-photon microscope was built with a FOV up to 418.5 μm (40× objective). The spatiotemporal dispersion was compensated simultaneously with a single custom-made prism. By means of dynamic power modulation, the variation of laser intensity within the FOV was reduced below 5%. The lateral and axial resolution of the system were 0.58-2.12 μm and 2.17-3.07 μm, respectively. Pollen grain images acquired by this system were presented to demonstrate the imaging capability at different positions across the entire FOV.

  14. Two-photon absorption cross section measurement in the gamma band system of nitric oxide

    SciTech Connect

    Burris, J.F. Jr.

    1982-01-01

    A dye laser with a single longitudinal mode and very stable spatial mode structure has been constructed. With this laser system a four-wave mixing experiment was done in the gamma bands of nitric oxide using two photon resonance. Another four-wave mixing experiment was done in nitrogen using coherent anti-Stokes Raman scattering (CARS) and the two signals ratioed. Using accurately known values of the Raman scattering cross section, the third order susceptibility in NO was determined without needing to know the spatial and temporal properties of the dye lasers. From this susceptibility, the two photon absorption cross section was calculated with the explicit dependence of sigma/sup (2)/ upon X/sup (3)/ shown. For the R/sub 22/ + S/sub 12/(J'' = 9 1/2) (A/sup 2/..sigma..+(v' = 0) -- X/sup 2/..pi..(v'' = 0)) line, sigma/sup (2)/ = (1.0 +/- 0.6) x 10/sup -38/cm/sup 4/g(2/sub 1/-Vertical Barsub f/ is the normalized lineshape. Branching ratios for the A/sup 2/..sigma..+(v' = n) ..-->.. X/sup 2/..omega..(v'' = n)(n = o,...9) transitions of NO were also measured, Franck-Condon factors calculated and the lifetime of the A state determined.

  15. Wide-band acousto-optic deflectors for large field of view two-photon microscope.

    PubMed

    Jiang, Runhua; Zhou, Zhenqiao; Lv, Xiaohua; Zeng, Shaoqun

    2012-04-01

    Acousto-optic deflector (AOD) is an attractive scanner for two-photon microscopy because it can provide fast and versatile laser scanning and does not involve any mechanical movements. However, due to the small scan range of available AOD, the field of view (FOV) of the AOD-based microscope is typically smaller than that of the conventional galvanometer-based microscope. Here, we developed a novel wide-band AOD to enlarge the scan angle. Considering the maximum acceptable acoustic attenuation in the acousto-optic crystal, relatively lower operating frequencies and moderate aperture were adopted. The custom AOD was able to provide 60 MHz 3-dB bandwidth and 80% peak diffraction efficiency at 840 nm wavelength. Based on a pair of such AOD, a large FOV two-photon microscope was built with a FOV up to 418.5 μm (40× objective). The spatiotemporal dispersion was compensated simultaneously with a single custom-made prism. By means of dynamic power modulation, the variation of laser intensity within the FOV was reduced below 5%. The lateral and axial resolution of the system were 0.58-2.12 μm and 2.17-3.07 μm, respectively. Pollen grain images acquired by this system were presented to demonstrate the imaging capability at different positions across the entire FOV. PMID:22559541

  16. High-power picosecond pulse delivery through hollow core photonic band gap fibers

    NASA Astrophysics Data System (ADS)

    Michieletto, Mattia; Johansen, Mette M.; Lyngsø, Jens K.; Lægsgaard, Jesper; Bang, Ole; Alkeskjold, Thomas T.

    2016-03-01

    We demonstrated robust and bend insensitive fiber delivery of high power laser with diffraction limited beam quality for two different kinds of hollow core band gap fibers. The light source for this experiment consists of ytterbium-doped double clad fiber aeroGAIN-ROD-PM85 in a high power amplifier setup. It provided 22ps pulses with a maximum average power of 95W, 40MHz repetition rate at 1032nm (~2.4μJ pulse energy), with M2 <1.3. We determined the facet damage threshold for a 7-cells hollow core photonic bandgap fiber and showed up to 59W average power output for a 5 meters fiber. The damage threshold for a 19-cell hollow core photonic bandgap fiber exceeded the maximum power provided by the light source and up to 76W average output power was demonstrated for a 1m fiber. In both cases, no special attention was needed to mitigate bend sensitivity. The fibers were coiled on 8 centimeters radius spools and even lower bending radii were present. In addition, stimulated rotational Raman scattering arising from nitrogen molecules was measured through a 42m long 19 cell hollow core fiber.

  17. 2D photonic crystal complete band gap search using a cyclic cellular automaton refination

    NASA Astrophysics Data System (ADS)

    González-García, R.; Castañón, G.; Hernández-Figueroa, H. E.

    2014-11-01

    We present a refination method based on a cyclic cellular automaton (CCA) that simulates a crystallization-like process, aided with a heuristic evolutionary method called differential evolution (DE) used to perform an ordered search of full photonic band gaps (FPBGs) in a 2D photonic crystal (PC). The solution is proposed as a combinatorial optimization of the elements in a binary array. These elements represent the existence or absence of a dielectric material surrounded by air, thus representing a general geometry whose search space is defined by the number of elements in such array. A block-iterative frequency-domain method was used to compute the FPBGs on a PC, when present. DE has proved to be useful in combinatorial problems and we also present an implementation feature that takes advantage of the periodic nature of PCs to enhance the convergence of this algorithm. Finally, we used this methodology to find a PC structure with a 19% bandgap-to-midgap ratio without requiring previous information of suboptimal configurations and we made a statistical study of how it is affected by disorder in the borders of the structure compared with a previous work that uses a genetic algorithm.

  18. Observation of nonlinear bands in near-field scanning optical microscopy of a photonic-crystal waveguide

    NASA Astrophysics Data System (ADS)

    Singh, A.; Ctistis, G.; Huisman, S. R.; Korterik, J. P.; Mosk, A. P.; Herek, J. L.; Pinkse, P. W. H.

    2015-01-01

    We have measured the photonic bandstructure of GaAs photonic-crystal waveguides with high resolution in energy as well as in momentum using near-field scanning optical microscopy. Intriguingly, we observe additional bands that are not predicted by eigenmode solvers, as was recently demonstrated by Huisman et al. [Phys. Rev. B 86, 155154 (2012)]. We study the presence of these additional bands by performing measurements of these bands while varying the incident light power, revealing a non-linear power dependence. Here, we demonstrate experimentally and theoretically that the observed additional bands are caused by a waveguide-specific near-field tip effect not previously reported, which can significantly phase-modulate the detected field.

  19. Observation of nonlinear bands in near-field scanning optical microscopy of a photonic-crystal waveguide

    SciTech Connect

    Singh, A.; Huisman, S. R.; Ctistis, G. Mosk, A. P.; Pinkse, P. W. H.; Korterik, J. P.; Herek, J. L.

    2015-01-21

    We have measured the photonic bandstructure of GaAs photonic-crystal waveguides with high resolution in energy as well as in momentum using near-field scanning optical microscopy. Intriguingly, we observe additional bands that are not predicted by eigenmode solvers, as was recently demonstrated by Huisman et al. [Phys. Rev. B 86, 155154 (2012)]. We study the presence of these additional bands by performing measurements of these bands while varying the incident light power, revealing a non-linear power dependence. Here, we demonstrate experimentally and theoretically that the observed additional bands are caused by a waveguide-specific near-field tip effect not previously reported, which can significantly phase-modulate the detected field.

  20. Simultaneous multi-channel CMW-band and MMW-band UWB monocycle pulse generation using FWM effect in a highly nonlinear photonic crystal fiber.

    PubMed

    Zhang, Fangzheng; Wu, Jian; Fu, Songnian; Xu, Kun; Li, Yan; Hong, Xiaobin; Shum, Ping; Lin, Jintong

    2010-07-19

    We propose and experimentally demonstrate a scheme to simultaneously realize multi-channel centimeter wave (CMW) band and millimeter wave (MMW) band ultra-wideband (UWB) monocycle pulse generation using four wave mixing (FWM) effect in a highly nonlinear photonic crystal fiber (HNL-PCF). Two lightwaves carrying polarity-reversed optical Gaussian pulses with appropriate time delay and another lightwave carrying a 20 GHz clock signal are launched into the HNL-PCF together. By filtering out the FWM idlers, two CMW-band UWB monocycle signals and two MMW-band UWB monocycle signals at 20 GHz are obtained simultaneously. Experimental measurements of the generated UWB monocycle pulses at individual wavelength, which comply with the FCC regulations, verify the feasibility and flexibility of proposed scheme for use in practical UWB communication systems.

  1. A super narrow band filter based on silicon 2D photonic crystal resonator and reflectors

    NASA Astrophysics Data System (ADS)

    Wang, Yuanyuan; Chen, Deyuan; Zhang, Gang; Wang, Juebin; Tao, Shangbin

    2016-03-01

    In this paper, a novel structure of super narrow band filter based on two-dimensional square lattice photonic crystals of silicon rods in air for 1.5 um communication is proposed and studied. COMSOL Multiphysics4.3b software is used to simulate the optical behavior of the filter. The filter consists of one point-defect-based resonator and two line-defect-based reflectors. The resonance frequency, transmission coefficient and quality factor are investigated by varying the parameters of the structure. In design, a silicon rod is removed to form the resonator; for the rows of rods above and below the resonator, a part of the rods are removed to form the reflectors. By optimizing the parameters of the filter, the quality factor and transmission coefficient of the filter at the resonance frequency of 2e14 Hz can reach 1330 and 0.953, respectively. The super narrow band filter can be integrated into optical circuit for its micron size. Also, it can be used for wavelength selection and noise filtering of optical amplifier in future communication application.

  2. High power experimental studies of hybrid photonic band gap accelerator structures

    NASA Astrophysics Data System (ADS)

    Zhang, JieXi; Munroe, Brian J.; Xu, Haoran; Shapiro, Michael A.; Temkin, Richard J.

    2016-08-01

    This paper reports the first high power tests of hybrid photonic band gap (PBG) accelerator structures. Three hybrid PBG (HPBG) structures were designed, built and tested at 17.14 GHz. Each structure had a triangular lattice array with 60 inner sapphire rods and 24 outer copper rods sandwiched between copper disks. The dielectric PBG band gap map allows the unique feature of overmoded operation in a TM02 mode, with suppression of both lower order modes, such as the TM11 mode, as well as higher order modes. The use of sapphire rods, which have negligible dielectric loss, required inclusion of the dielectric birefringence in the design. The three structures were designed to sequentially reduce the peak surface electric field. Simulations showed relatively high surface fields at the triple point as well as in any gaps between components in the clamped assembly. The third structure used sapphire rods with small pin extensions at each end and obtained the highest gradient of 19 MV /m , corresponding to a surface electric field of 78 MV /m , with a breakdown probability of 5 ×10-1 per pulse per meter for a 100-ns input power pulse. Operation at a gradient above 20 MV /m led to runaway breakdowns with extensive light emission and eventual damage. For all three structures, multipactor light emission was observed at gradients well below the breakdown threshold. This research indicated that multipactor triggered at the triple point limited the operational gradient of the hybrid structure.

  3. Photonically enabled Ka-band radar and infrared sensor subscale testbed

    NASA Astrophysics Data System (ADS)

    Lohr, Michele B.; Sova, Raymond M.; Funk, Kevin B.; Airola, Marc B.; Dennis, Michael L.; Pavek, Richard E.; Hollenbeck, Jennifer S.; Garrison, Sean K.; Conard, Steven J.; Terry, David H.

    2014-10-01

    A subscale radio frequency (RF) and infrared (IR) testbed using novel RF-photonics techniques for generating radar waveforms is currently under development at The Johns Hopkins University Applied Physics Laboratory (JHU/APL) to study target scenarios in a laboratory setting. The linearity of Maxwell's equations allows the use of millimeter wavelengths and scaled-down target models to emulate full-scale RF scene effects. Coupled with passive IR and visible sensors, target motions and heating, and a processing and algorithm development environment, this testbed provides a means to flexibly and cost-effectively generate and analyze multi-modal data for a variety of applications, including verification of digital model hypotheses, investigation of correlated phenomenology, and aiding system capabilities assessment. In this work, concept feasibility is demonstrated for simultaneous RF, IR, and visible sensor measurements of heated, precessing, conical targets and of a calibration cylinder. Initial proof-of-principle results are shown of the Ka-band subscale radar, which models S-band for 1/10th scale targets, using stretch processing and Xpatch models.

  4. The absolute amplitude calibration of the SEASAT synthetic aperture radar - An intercomparison with other L-band radar systems

    NASA Technical Reports Server (NTRS)

    Held, D.; Werner, C.; Wall, S.

    1983-01-01

    The absolute amplitude calibration of the spaceborne Seasat SAR data set is presented based on previous relative calibration studies. A scale factor making it possible to express the perceived radar brightness of a scene in units of sigma-zero is established. The system components are analyzed for error contribution, and the calibration techniques are introduced for each stage. These include: A/D converter saturation tests; prevention of clipping in the processing step; and converting the digital image into the units of received power. Experimental verification was performed by screening and processing the data of the lava flow surrounding the Pisgah Crater in Southern California, for which previous C-130 airborne scatterometer data were available. The average backscatter difference between the two data sets is estimated to be 2 dB in the brighter, and 4 dB in the dimmer regions. For the SAR a calculated uncertainty of 3 dB is expected.

  5. Photonic vector signal generation at W-band employing an optical frequency octupling scheme enabled by a single MZM

    NASA Astrophysics Data System (ADS)

    Li, Xinying; Yu, Jianjun; Zhang, Ziran; Xiao, Jiangnan; Chang, Gee-Kung

    2015-08-01

    We propose photonic vector signal generation at millimeter-wave (mm-wave) bands enabled by a single Mach-Zehnder modulator (MZM) and phase-precoding technique, which can realize photonic frequency multiplication of the precoded microwave vector signal used for the drive of the single MZM. We also experimentally demonstrate the generation of quadrature-phase-shift-keying (QPSK) modulated vector signal at W-band adopting photonic frequency octupling (×8) based on our proposed scheme. The MZM is driven by a 12-GHz QPSK modulated precoded vector signal. Up to 4-Gbaud QPSK-modulated electrical vector signal at 96 GHz is generated and then delivered over 3-m wireless transmission distance.

  6. Narrow-band GeV photons generated from an x-ray free-electron laser oscillator

    NASA Astrophysics Data System (ADS)

    Hajima, Ryoichi; Fujiwara, Mamoru

    2016-02-01

    We propose a scheme to generate narrow-band GeV photons, γ -rays, via Compton scattering of hard x-ray photons in an x-ray free-electron laser oscillator. Generated γ -rays show a narrow-band spectrum with a sharp peak, ˜0.1 % (FWHM), due to large momentum transfer from electrons to photons. The γ -ray beam has a spectral density of ˜102 ph /(MeV s ) with a typical set of parameters based on a 7-GeV electron beam operated at 3-MHz repetition, Such γ -rays will be a unique probe for studying hadron physics. Features of the γ -ray source, flux, spectrum, polarization, tunability and energy resolution are discussed.

  7. Easy Absolute Values? Absolutely

    ERIC Educational Resources Information Center

    Taylor, Sharon E.; Mittag, Kathleen Cage

    2015-01-01

    The authors teach a problem-solving course for preservice middle-grades education majors that includes concepts dealing with absolute-value computations, equations, and inequalities. Many of these students like mathematics and plan to teach it, so they are adept at symbolic manipulations. Getting them to think differently about a concept that they…

  8. Group velocity enhancement for guided lightwave by band-pulling effect in single-mode silicon comb photonic crystal wires

    NASA Astrophysics Data System (ADS)

    Thubthimthong, Borriboon; Hane, Kazuhiro

    2015-05-01

    Photonic crystal waveguides (PCWs), which usually exhibit the slow-light effect near the band edge frequency, may in fact be used to induce higher group velocity (vg). The presence of the band edge, due to periodically carving a strip waveguide (SW) into a PCW of a comb-shape dielectric wire, results in the band-pulling effect. The band-pulling effect, which lifts the fundamental photonic band toward the band gap, not only enhances vg by reducing the effective index but also prevents the band from bending toward the light cone of the core material, leading to additional vg enhancement. The maximum PCW vg (0.43c; c = vacuum light speed) found from numerical modeling was higher than SW vg at all widths and thicknesses, except for extremely low thickness below 80 nm. We found by numerical modeling and experiments that up to 75% enhancement at the 1550 nm wavelength may be achieved in a fabricated single-mode PCW (0.38c) compared with an SW (0.21c) of the same width and thickness. The higher vg was confirmed by measuring the PCW’s group index using ring resonators. The PCW propagation loss of 2.1 dB mm-1 and the bandwidth-distance product of 100 Gb/s-cm were deduced from experimental results. Our findings seemed encouraging for employing PCWs in optical interconnect applications.

  9. Influence of photonic stop band effect on photoluminescence of Y 2O 3:Eu 3+ inverse opal films

    NASA Astrophysics Data System (ADS)

    Qu, Xuesong; Dong, Biao; Pan, Guohui; Bai, Xue; Dai, Qilin; Zhang, Hui; Qin, Ruifei; Song, Hongwei

    2011-06-01

    Y 2O 3:Eu 3+ inverse opal films were fabricated by the self-assembly technique, which had a lattice parameter of ˜260 nm and a photonic stop band at 520 nm. Near the center of the photonic stop band, both the emission intensity and the spontaneous transition rate of 5D 1- 7F 1 transitions were modified. At the band gap edge, no obvious change was observed for the 5D 0- 7F J spontaneous transition rate, however, the emission intensity of 5D 0- 7F J ( J = 0, 1) was depressed in contrast to the 5D 0- 7F 2, which improved the color purity of the red emission.

  10. Atom-atom interactions around the band edge of a photonic crystal waveguide

    NASA Astrophysics Data System (ADS)

    Hood, Jonathan D.; Goban, Akihisa; Asenjo-Garcia, Ana; Lu, Mingwu; Yu, Su-Peng; Chang, Darrick E.; Kimble, H. J.

    2016-09-01

    Tailoring the interactions between quantum emitters and single photons constitutes one of the cornerstones of quantum optics. Coupling a quantum emitter to the band edge of a photonic crystal waveguide (PCW) provides a unique platform for tuning these interactions. In particular, the cross-over from propagating fields E(x)e±ikxxE(x)∝e±ikxx outside the bandgap to localized fields E(x)e-κx|x|E(x)∝e-κx|x| within the bandgap should be accompanied by a transition from largely dissipative atom-atom interactions to a regime where dispersive atom-atom interactions are dominant. Here, we experimentally observe this transition by shifting the band edge frequency of the PCW relative to the D1D1 line of atomic cesium for N¯=3.0±0.5

  11. True-time-delay photonic beamformer for an L-band phased array radar

    NASA Astrophysics Data System (ADS)

    Zmuda, Henry; Toughlian, Edward N.; Payson, Paul M.; Malowicki, John E.

    1995-10-01

    The problem of obtaining a true-time-delay photonic beamformer has recently been a topic of great interest. Many interesting and novel approaches to this problem have been studied. This paper examines the design, construction, and testing of a dynamic optical processor for the control of a 20-element phased array antenna operating at L-band (1.2-1.4 GHz). The approach taken here has several distinct advantages. The actual optical control is accomplished with a class of spatial light modulator known as a segmented mirror device (SMD). This allows for the possibility of controlling an extremely large number (tens of thousands) of antenna elements using integrated circuit technology. The SMD technology is driven by the HDTV and laser printer markets so ultimate cost reduction as well as technological improvements are expected. Optical splitting is efficiently accomplished using a diffractive optical element. This again has the potential for use in antenna array systems with a large number of radiating elements. The actual time delay is achieved using a single acousto-optic device for all the array elements. Acousto-optic device technologies offer sufficient delay as needed for a time steered array. The topological configuration is an optical heterodyne system, hence high, potentially millimeter wave center frequencies are possible by mixing two lasers of slightly differing frequencies. Finally, the entire system is spatially integrated into a 3D glass substrate. The integrated system provides the ruggedness needed in most applications and essentially eliminates the drift problems associated with free space optical systems. Though the system is presently being configured as a beamformer, it has the ability to operate as a general photonic signal processing element in an adaptive (reconfigurable) transversal frequency filter configuration. Such systems are widely applicable in jammer/noise canceling systems, broadband ISDN, and for spread spectrum secure communications

  12. Synthesis and photonic band calculations of NCP face-centered cubic photonic crystals of TiO2 hollow spheres.

    PubMed

    Zhu, Yong-zheng; Cao, Yan-ling; Li, Zhi-hui; Ding, Juan; Liu, Jun-song; Chi, Yuan-bin

    2007-02-01

    With the help of self-assembly, thermal sintering, selective etching techniques and sol-gel process, the non-close packed (ncp) face-centered cubic (fcc) photonic crystals of titanium dioxide (TiO2) hollow spheres connected by TiO2 cylindrical tubes have been fabricated using silica template. The photonic bandgap calculations indicate that the ncp structure of TiO2 hollow spheres was easier to open the pseudogaps than close packed system at the lowest energy.

  13. Two-photon LIF on the HIT-SI3 experiment: Absolute density and temperature measurements of deuterium neutrals

    NASA Astrophysics Data System (ADS)

    Elliott, Drew; Sutherland, Derek; Siddiqui, Umair; Scime, Earl; Everson, Chris; Morgan, Kyle; Hossack, Aaron; Nelson, Brian; Jarboe, Tom

    2016-11-01

    Two-photon laser-induced fluorescence measurements were performed on the helicity injected torus (HIT-SI3) device to determine the density and temperature of the background neutral deuterium population. Measurements were taken in 2 ms long pulsed plasmas after the inductive helicity injectors were turned off. Attempts to measure neutrals during the main phase of the plasma were unsuccessful, likely due to the density of neutrals being below the detection threshold of the diagnostic. An unexpectedly low density of atomic deuterium was measured in the afterglow; roughly 100 times lower than the theoretical prediction of 1017 m-3. The neutral temperatures measured were on the order of 1 eV. Temporally and spatially resolved neutral density and temperature data are presented.

  14. Band structure of cavity-type hypersonic phononic crystals fabricated by femtosecond laser-induced two-photon polymerization

    NASA Astrophysics Data System (ADS)

    Rakhymzhanov, A. M.; Gueddida, A.; Alonso-Redondo, E.; Utegulov, Z. N.; Perevoznik, D.; Kurselis, K.; Chichkov, B. N.; El Boudouti, E. H.; Djafari-Rouhani, B.; Fytas, G.

    2016-05-01

    The phononic band diagram of a periodic square structure fabricated by femtosecond laser pulse-induced two photon polymerization is recorded by Brillouin light scattering (BLS) at hypersonic (GHz) frequencies and computed by finite element method. The theoretical calculations along the two main symmetry directions quantitatively capture the band diagrams of the air- and liquid-filled structure and moreover represent the BLS intensities. The theory helps identify the observed modes, reveals the origin of the observed bandgaps at the Brillouin zone boundaries, and unravels direction dependent effective medium behavior.

  15. The properties of photonic band gaps for three-dimensional tunable photonic crystals with simple-cubic lattices doped by magnetized plasma

    NASA Astrophysics Data System (ADS)

    Zhang, Hai-Feng; Liu, Shao-Bin; Li, Bing-Xiang

    2013-09-01

    In this paper, the properties of photonic band gaps (PBGs) for two types of three-dimensional magnetized plasma photonic crystals (MPPCs) composed of homogeneous magnetized plasma and dielectric with simple-cubic lattices are theoretically investigated based on a modified plane wave expansion (PWE) method, as incidence electromagnetic (EM) wave vector is parallel to the external magnetic field. The equations for calculating the band diagrams in the first irreducible Brillouin zone of two types of photonic crystals (dielectric spheres immersed in magnetized plasma background or vice versa), are theoretically deduced. The influences of dielectric constant of dielectric, plasma collision frequency, filling factor, the external magnetic field and plasma frequency on the properties of PBGs for both types of MPPCs are discussed in detail, respectively, and some corresponding physical explanations are also given. The characteristics of flatbands region are also discussed. From the numerical results, it has been shown that not only the bandwidths but also the relative bandwidths of the PBGs for both types of three-dimensional MPPCs can be manipulated by the plasma frequency, filling factor, external magnetic field and relative dielectric constant of dielectric, respectively. However, the plasma collision frequency has no effect on the frequency ranges and relative bandwidths of the PBGs for two types of three-dimensional MPPCs. The location of flatbands region can not be tuned by any parameters except for the plasma frequency and the external magnetic field.

  16. Dual-function photonic integrated circuit for frequency octo-tupling or single-side-band modulation.

    PubMed

    Hasan, Mehedi; Maldonado-Basilio, Ramón; Hall, Trevor J

    2015-06-01

    A dual-function photonic integrated circuit for microwave photonic applications is proposed. The circuit consists of four linear electro-optic phase modulators connected optically in parallel within a generalized Mach-Zehnder interferometer architecture. The photonic circuit is arranged to have two separate output ports. A first port provides frequency up-conversion of a microwave signal from the electrical to the optical domain; equivalently single-side-band modulation. A second port provides tunable millimeter wave carriers by frequency octo-tupling of an appropriate amplitude RF carrier. The circuit exploits the intrinsic relative phases between the ports of multi-mode interference couplers to provide substantially all the static optical phases needed. The operation of the proposed dual-function photonic integrated circuit is verified by computer simulations. The performance of the frequency octo-tupling and up-conversion functions is analyzed in terms of the electrical signal to harmonic distortion ratio and the optical single side band to unwanted harmonics ratio, respectively.

  17. Tunable all-angle negative refraction and photonic band gaps in two-dimensional plasma photonic crystals with square-like Archimedean lattices

    SciTech Connect

    Zhang, Hai-Feng E-mail: lsb@nuaa.edu.cn; Liu, Shao-Bin E-mail: lsb@nuaa.edu.cn; Jiang, Yu-Chi

    2014-09-15

    In this paper, the tunable all-angle negative refraction and photonic band gaps (PBGs) in two types of two-dimensional (2D) plasma photonic crystals (PPCs) composed of homogeneous plasma and dielectric (GaAs) with square-like Archimedean lattices (ladybug and bathroom lattices) for TM wave are theoretically investigated based on a modified plane wave expansion method. The type-1 structure is dielectric rods immersed in the plasma background, and the complementary structure is named as type-2 PPCs. Theoretical simulations demonstrate that the both types of PPCs with square-like Archimedean lattices have some advantages in obtaining the higher cut-off frequency, the larger PBGs, more number of PBGs, and the relative bandwidths compared to the conventional square lattices as the filling factor or radius of inserted rods is same. The influences of plasma frequency and radius of inserted rod on the properties of PBGs for both types of PPCs also are discussed in detail. The calculated results show that PBGs can be manipulated by the parameters as mentioned above. The possibilities of all-angle negative refraction in such two types of PPCs at low bands also are discussed. Our calculations reveal that the all-angle negative phenomena can be observed in the first two TM bands, and the frequency range of all-angle negative refraction can be tuned by changing plasma frequency. Those properties can be used to design the optical switching and sensor.

  18. Tunable all-angle negative refraction and photonic band gaps in two-dimensional plasma photonic crystals with square-like Archimedean lattices

    NASA Astrophysics Data System (ADS)

    Zhang, Hai-Feng; Liu, Shao-Bin; Jiang, Yu-Chi

    2014-09-01

    In this paper, the tunable all-angle negative refraction and photonic band gaps (PBGs) in two types of two-dimensional (2D) plasma photonic crystals (PPCs) composed of homogeneous plasma and dielectric (GaAs) with square-like Archimedean lattices (ladybug and bathroom lattices) for TM wave are theoretically investigated based on a modified plane wave expansion method. The type-1 structure is dielectric rods immersed in the plasma background, and the complementary structure is named as type-2 PPCs. Theoretical simulations demonstrate that the both types of PPCs with square-like Archimedean lattices have some advantages in obtaining the higher cut-off frequency, the larger PBGs, more number of PBGs, and the relative bandwidths compared to the conventional square lattices as the filling factor or radius of inserted rods is same. The influences of plasma frequency and radius of inserted rod on the properties of PBGs for both types of PPCs also are discussed in detail. The calculated results show that PBGs can be manipulated by the parameters as mentioned above. The possibilities of all-angle negative refraction in such two types of PPCs at low bands also are discussed. Our calculations reveal that the all-angle negative phenomena can be observed in the first two TM bands, and the frequency range of all-angle negative refraction can be tuned by changing plasma frequency. Those properties can be used to design the optical switching and sensor.

  19. Chirped photonic crystal mode converters for broad-band coupling with highly dispersive photonic crystal microring resonators

    NASA Astrophysics Data System (ADS)

    Lo, Stanley M.; Lee, Jonathan Y.; Weiss, Sharon M.; Fauchet, Philippe M.

    2014-03-01

    We demonstrate evanescent coupling between a photonic crystal (PhC) waveguide and a PhC embedded microring resonator on the silicon-on-insulator platform. The mode converter comprises 6 linearly chirped air holes that adiabatically couple the light between the silicon waveguide mode and the PhC mode. Three-dimensional finitedifference time-domain simulations reveal a coupling bandwidth of >100nm. From our experiment, the optical spectra show a photonic bandgap located below ~1590nm. At the resonances in the slow-light regime, a loaded quality factor as high as ~2500 was measured and a group index of ~16 in the PhC embedded microring resonator was estimated from the non-uniform free spectral ranges.

  20. One-photon band gap engineering of borate glass doped with ZnO for photonics applications

    SciTech Connect

    Abdel-Baki, Manal; Abdel-Wahab, Fathy A.; El-Diasty, Fouad

    2012-04-01

    Lithium tungsten borate glass of the composition (0.56-x)B{sub 2}O{sub 3}-0.4Li{sub 2}O-xZnO-0.04WO{sub 3} (0 {<=}x{<=} 0.1 mol. %) is prepared for photonics applications. The glass is doped with ZnO to tune the glass absorption characteristics in a wide spectrum range (200-2500 nm). Chemical bond approach, including chemical structure, electronegativity, bond ionicity, nearest-neighbor coordination, and other chemical bonding aspect, is used to analyze and to explain the obtained glass properties such as: transmittance, absorption, electronic structure parameters (bandgap, Fermi level, and Urbach exciton-phonon coupling), Wannier free excitons excitation (applying Elliott's model), and two-photon absorption coefficient as a result of replacement of B{sub 2}O{sub 3} by ZnO.

  1. Modeling of a wide band pass optical filter based on 1D ternary dielectric-metallic-dielectric photonic crystals

    NASA Astrophysics Data System (ADS)

    Rafat, Nadia H.; El-Naggar, Sahar A.; Mostafa, Samia I.

    2011-08-01

    We suggest ternary structures of dielectric-metal-dielectric photonic structures to be used as optical band pass filters. We theoretically study and evaluate the optical properties of these one-dimensional structures. ZnSe/metal/LiF and SiC/metal/SiO2 with three metals, namely silver, gold and copper, are suggested as the optical filters. We calculated the reflectance and the transmittance of electromagnetic waves (EMW) out of these structures using the transfer matrix method. These calculations take place for the case of normal and oblique incidences using actual measured values for the indices of refraction. Our calculations show that such photonic crystal (PC) filters have a well shaped pass band in the visible range and block efficiently ultraviolet and infrared EMW. Our results show that PCs having silver as the metal layer are preferred to those having gold and copper because of the high transmittance in the visible range. A SiC/Ag/SiO2 filter shows better performance than a ZnSe/Ag/LiF one from the transmittance and the shape of the band points of view. Such a filter shows a well shaped wide band over the range of incident angles from 0° to 80°.

  2. Photonic band structures of periodic arrays of pores in a metallic host: tight-binding beyond the quasistatic approximation.

    PubMed

    Kim, Kwangmoo; Stroud, D

    2013-08-26

    We have calculated the photonic band structures of metallic inverse opals and of periodic linear chains of spherical pores in a metallic host, below a plasma frequency ωp. In both cases, we use a tight-binding approximation, assuming a Drude dielectric function for the metallic component, but without making the quasistatic approximation. The tight-binding modes are linear combinations of the single-cavity transverse magnetic (TM) modes. For the inverse-opal structures, the lowest modes are analogous to those constructed from the three degenerate atomic p-states in fcc crystals. For the linear chains, in the limit of small spheres compared to a wavelength, the results bear some qualitative resemblance to the dispersion relation for metal spheres in an insulating host, as calculated by Brongersma et al. [Phys. Rev. B 62, R16356 (2000)]. Because the electromagnetic fields of these modes decay exponentially in the metal, there are no radiative losses, in contrast to the case of arrays of metallic spheres in air. We suggest that this tight-binding approach to photonic band structures of such metallic inverse materials may be a useful approach for studying photonic crystals containing metallic components, even beyond the quasistatic approximation. PMID:24105532

  3. Ground-based Photon Path Measurements from Solar Absorption Spectra of the O2 A-band

    NASA Technical Reports Server (NTRS)

    Yang, Z.; Wennberg, P. O.; Cageao, R. P.; Pongetti, T. J.; Toon, G. C.; Sander, S. P.

    2005-01-01

    High-resolution solar absorption spectra obtained from Table Mountain Facility (TMF, 34.38degN, 117.68degW, 2286 m elevation) have been analyzed in the region of the O2 A-band. The photon paths of direct sunlight in clear sky cases are retrieved from the O2 absorption lines and compared with ray-tracing calculations based on the solar zenith angle and surface pressure. At a given zenith angle, the ratios of retrieved to geometrically derived photon paths are highly precise (approx.0.2%), but they vary as the zenith angle changes. This is because current models of the spectral lineshape in this band do not properly account for the significant absorption that exists far from the centers of saturated lines. For example, use of a Voigt function with Lorentzian far wings results in an error in the retrieved photon path of as much as 5%, highly correlated with solar zenith angle. Adopting a super-Lorentz function reduces, but does not completely eliminate this problem. New lab measurements of the lineshape are required to make further progress.

  4. Photonic band structures of periodic arrays of pores in a metallic host: tight-binding beyond the quasistatic approximation

    NASA Astrophysics Data System (ADS)

    Kim, Kwangmoo; Stroud, David

    2014-03-01

    We have calculated the photonic band structures of metallic inverse opals and of periodic linear chains of spherical pores in a metallic host, below a plasma frequency ωp. In both cases, we use a tight-binding approximation, assuming a Drude dielectric function for the metallic component, but without making the quasistatic approximation. The tight-binding modes are linear combinations of the single-cavity transverse magnetic (TM) modes. For the inverse-opal structures, the lowest modes are analogous to those constructed from the three degenerate atomic p-states in fcc crystals. For the linear chains, in the limit of small spheres compared to a wavelength, the results bear some qualitative resemblance to the dispersion relation for metal spheres in an insulating host, as calculated by Brongersma et al. [Phys. Rev. B 62, R16356 (2000)]. Because the electromagnetic fields of these modes decay exponentially in the metal, there are no radiative losses, in contrast to the case of arrays of metallic spheres in air. We suggest that this tight-binding approach to photonic band structures of such metallic inverse materials may be a useful approach for studying photonic crystals containing metallic components. This work was supported by KIAS, by NSF-MRSEC at OSU (DMR-0820414), and by DOE Grant No. DE-FG02-07ER46424. Computing resources were provided by OSC and by Abacus at KIAS.

  5. Experimental evidence of the photonic band gap in hybrid one-dimensional photonic crystal based on a mixture of (HMDSO, O2)

    NASA Astrophysics Data System (ADS)

    Amri, R.; Sahel, S.; Manaa, C.; Bouaziz, L.; Gamra, D.; Lejeune, M.; Clin, M.; Zellama, K.; Bouchriha, H.

    2016-08-01

    Hybrid One-dimensional photonic crystal coated from a mixture of an organic compound (HMDSO) and oxygen (O2) is elaborated by PECVD technique. The originality of the method consists in obtaining layers of different permittivity with the same gas mixture, but with different flow. The change in flow is optimized to obtain organic/inorganic layers of good quality with high and low refractive index of 2.1 and 1.4 corresponding respectively to HMDSO and SiO2 materials as assigned by IR measurement. Evidence of the photonic band gap is obtained by measuring the transmissions and reflections spectra which show that it appears only after 13 periods with a width of 325 nm corresponding to energy 3.8 eV. We have also introduced a defect in this photonic structure by changing the thickness of central layer, and observed the presence of a frequency mode corresponding to this defect. Our results are interpreted by using a theoretical model based on transfer matrix wich well reproduced the experimental data.

  6. Single Particle-Photon Imaging Detector With 4-Dimensional Output: Absolute Time-of-hit, X-Y Position, and PHA: Applications in Space Science Instruments

    NASA Astrophysics Data System (ADS)

    Paschalidis, N. P.; Mitchell, D. G.; Brandt, P. C.

    2006-12-01

    A detector that can simultaneously measure time, position, and pulse high analysis (PHA) of single particle/photons with high resolutions and speeds, is a strong enabling technology for many space science instruments such as: energetic neutral atom imagers, low energy neutrals, energetic particle spectrometers, ion/electron plasma analyzers, UV spectrographs, mass spectrometers, laser range finding imagers, X-ray imagers. This presentation describes one such 4-dimentional detector based on micro-channel plates (MCPs), delay line anodes, and precise time of flight, and charge integration electronics for PHA. More specifically the detector includes: a) An MCP in 2-stack or Z-stack configuration for the particle/photon detection. b) Option for a thin foil or photo-cathode in front of the MCP to increase the detection efficiency of particles or photons respectively. c) Novel 1D or 2D delay line anode adaptable to almost any geometry and physical size of common instruments mentioned above. d) Fast time of flight (TOF) electronics for the absolute time of hit and the X-Y position determination. e) Fast charge integration electronics for PHA of the total charge released by the MCP. Under certain circumstances the PHA gives information about the particle mass such as for protons, He and Oxygen, cross calibrated against UV light which typically gives a single electron distribution. f) FPGA electronics for digital data acquisition and handling. e) Standard mat lab SW for data analysis and visualization in a stand alone application. The detector achieves time of hit accuracy <50ps, X-Y position resolution <20um in a field of 2048 x 2048 pixels (2048 for 1D) and adjustable speeds of: 10MHz at 256 x 256 pixels to 1MHz at 2048 x 2048 pixels. The total-charge analysis is at 10-bits. The detector can be used in its full 4D configuration such as in TOF imaging particle analyzer (i.e ENA), or in a reduced configuration such as in a UV spectrograph with X-Y position only. Typical

  7. The Voigt effects in the anisotropic photonic band gaps of three-dimensional magnetized plasma photonic crystals doped by the uniaxial material

    NASA Astrophysics Data System (ADS)

    Zhang, Hai-Feng; Liu, Shao-Bin; Li, Bing-Xiang

    2013-10-01

    In this paper, the properties of photonic band gaps (PBGs) for three-dimensional magnetized plasma photonic crystals (MPPCs) composed of anisotropic dielectric (the uniaxial material) spheres immersed in homogeneous magnetized plasma background with simple-cubic lattices are theoretically investigated by the plane wave expansion (PWE) method, as the Voigt effects of magnetized plasma are considered. The equations for calculating the anisotropic PBGs in the first irreducible Brillouin zone are theoretically deduced. The anisotropic PBGs and two flatband regions can be obtained. The effects of the ordinary-refractive index, extraordinary-refractive index, filling factor, plasma frequency and plasma cyclotron frequency on the characteristics of anisotropic PBGs for the three-dimensional MPPCs are studied in detail and some corresponding physical explanations are also given. The numerical results show that the anisotropy can open partial band gaps in simple-cubic lattices and the complete PBGs can be found compared to the conventional three-dimensional MPPCs doped by the isotropic material. The bandwidths of PBGs can be enlarged by introducing the magnetized plasma into three-dimensional PCs containing the uniaxial material. It is also shown that the anisotropic PBGs can be manipulated by the ordinary-refractive index, extraordinary-refractive index, filling factor, plasma frequency and plasma cyclotron frequency. The locations of flatband regions cannot be tuned by any parameters except for the plasma frequency and plasma cyclotron frequency. Introducing the uniaxial material in three-dimensional magnetized plasma-dielectric photonic crystals can enlarge the PBGs and also provide a way to obtain the complete PBGs as the three-dimensional MPPCs with high symmetry.

  8. Absolute atomic oxygen density measurements for nanosecond-pulsed atmospheric-pressure plasma jets using two-photon absorption laser-induced fluorescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Jiang, C.; Carter, C.

    2014-12-01

    Nanosecond-pulsed plasma jets that are generated under ambient air conditions and free from confinement of electrodes have become of great interest in recent years due to their promising applications in medicine and dentistry. Reactive oxygen species that are generated by nanosecond-pulsed, room-temperature non-equilibrium He-O2 plasma jets among others are believed to play an important role during the bactericidal or sterilization processes. We report here absolute measurements of atomic oxygen density in a 1 mm-diameter He/(1%)O2 plasma jet at atmospheric pressure using two-photon absorption laser-induced fluorescence spectroscopy. Oxygen number density on the order of 1013 cm-3 was obtained in a 150 ns, 6 kV single-pulsed plasma jet for an axial distance up to 5 mm above the device nozzle. Temporally resolved O density measurements showed that there are two maxima, separated in time by 60-70 µs, and a total pulse duration of 260-300 µs. Electrostatic modeling indicated that there are high-electric-field regions near the nozzle exit that may be responsible for the observed temporal behavior of the O production. Both the field-distribution-based estimation of the time interval for the O number density profile and a pulse-energy-dependence study confirmed that electric-field-dependent, direct and indirect electron-induced processes play important roles for O production.

  9. Absolute cross sections and branching ratios for the radiative decay of doubly excited helium determined by photon-induced fluorescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Mickat, S.; Schartner, K.-H.; Kammer, Sv; Schill, R.; Werner, L.; Klumpp, S.; Ehresmann, A.; Schmoranzer, H.; Sukhorukov, V. L.

    2005-08-01

    The decay of doubly excited helium states below the N = 2 threshold, cascading radiatively over three steps, were investigated using the photon-induced fluorescence spectroscopy (PIFS) at BESSY II. Absolute cross sections as the product of the resonance excitation cross section of the doubly excited states and their fluorescence rate to decay into the singly excited 1sms(1S) and 1smd(1D) states were measured. The experiments showed that the (sp,2n+)(1P) states decay predominantly into the 1sns(1S) states, whereas the (pd,2n)(1P) states prefer to decay into the 1snd(1D) states. For the (sp,2n-)(1P) states with n = 4, 5 and 6 we observed a broad and complex decay pattern. In addition the angular distribution of the fluorescence radiation was measured. The results are in good agreement with theoretical predictions. Furthermore, the weakening of the LS coupling scheme and the mixing between singlet and triplet states in helium was confirmed by observation of the 1s6d(3D0,1,2) → 1s2p(3P0,1,2) transition on a doubly excited singlet state.

  10. Analyzing the photonic band gaps in two-dimensional plasma photonic crystals with fractal Sierpinski gasket structure based on the Monte Carlo method

    NASA Astrophysics Data System (ADS)

    Zhang, Hai-Feng; Liu, Shao-Bin

    2016-08-01

    In this paper, the properties of photonic band gaps (PBGs) in two types of two-dimensional plasma-dielectric photonic crystals (2D PPCs) under a transverse-magnetic (TM) wave are theoretically investigated by a modified plane wave expansion (PWE) method where Monte Carlo method is introduced. The proposed PWE method can be used to calculate the band structures of 2D PPCs which possess arbitrary-shaped filler and any lattice. The efficiency and convergence of the present method are discussed by a numerical example. The configuration of 2D PPCs is the square lattices with fractal Sierpinski gasket structure whose constituents are homogeneous and isotropic. The type-1 PPCs is filled with the dielectric cylinders in the plasma background, while its complementary structure is called type-2 PPCs, in which plasma cylinders behave as the fillers in the dielectric background. The calculated results reveal that the enough accuracy and good convergence can be obtained, if the number of random sampling points of Monte Carlo method is large enough. The band structures of two types of PPCs with different fractal orders of Sierpinski gasket structure also are theoretically computed for a comparison. It is demonstrate that the PBGs in higher frequency region are more easily produced in the type-1 PPCs rather than in the type-2 PPCs. Sierpinski gasket structure introduced in the 2D PPCs leads to a larger cutoff frequency, enhances and induces more PBGs in high frequency region. The effects of configurational parameters of two types of PPCs on the PBGs are also investigated in detail. The results show that the PBGs of the PPCs can be easily manipulated by tuning those parameters. The present type-1 PPCs are more suitable to design the tunable compacted devices.

  11. Efficient frequency downconversion at the single photon level from the red spectral range to the telecommunications C-band.

    PubMed

    Zaske, Sebastian; Lenhard, Andreas; Becher, Christoph

    2011-06-20

    We report on single photon frequency downconversion from the red part of the spectrum (738 nm) to the telecommunications C-band. By mixing attenuated laser pulses with an average photon number per pulse < 1 with a strong continuous light field at 1403 nm in a periodically poled Zn:LiNbO3 ridge waveguide an internal conversion efficiency of ∼ 73% is achieved. We further investigate the noise properties of the process by measuring the output spectrum. Our results indicate that by narrow spectral filtering a quantum interface should be feasible which bridges the wavelength gap between quantum emitters like color centers in diamond emitting in the red part of the spectrum and low-loss fiber-optic telecommunications wavelengths.

  12. Periodic layered inverse micelle multilayers with tunable photonic band gap: fabrication and application in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Jang, Yoon Hee; Kim, Dong Ha

    2014-03-01

    Periodic organic-inorganic multilayer films are constructed by stepwise alternate build-up of UV-stabilized poly(styrene-block-vinylpyridine) block copolymer inverse micelles and poly(styrene-block-ethylene oxide) block copolymer layers containing inorganic moieties at the polar core blocks. The layered block copolymer inverse micelle films show strong reflective color and well-defined photonic stop bands in the entire wavelength region from visible to near IR, which can be fine-tuned by controlling the inner architectures, i.e., the periodic size of the layered structure. The layered block copolymer films are integrated into the back-side of counter electrodes as a light reflection layer and thereby an enhancement ratio of ~11% in the cell efficiency is achieved, which can be attributed to the increased light harvesting by the sensitized dye molecules. Tailoring the inner structure of the photonic band gap multilayers, the wavelength of reflected light can be adjusted to the wavelength of dye absorption, leading to a noticeable enhancement in photocurrent and power conversion efficiency.Periodic organic-inorganic multilayer films are constructed by stepwise alternate build-up of UV-stabilized poly(styrene-block-vinylpyridine) block copolymer inverse micelles and poly(styrene-block-ethylene oxide) block copolymer layers containing inorganic moieties at the polar core blocks. The layered block copolymer inverse micelle films show strong reflective color and well-defined photonic stop bands in the entire wavelength region from visible to near IR, which can be fine-tuned by controlling the inner architectures, i.e., the periodic size of the layered structure. The layered block copolymer films are integrated into the back-side of counter electrodes as a light reflection layer and thereby an enhancement ratio of ~11% in the cell efficiency is achieved, which can be attributed to the increased light harvesting by the sensitized dye molecules. Tailoring the inner

  13. A high peak power S-band switching system for the Advanced Photon Source (APS) Linear Accelerator (Linac).

    SciTech Connect

    Grelick, A. E.

    1998-09-11

    An S-band linear accelerator is the source of particles and front end of the Advanced Photon Source [1] injector. Additionally, it will be used to support a low-energy undulator test line (LEUTL) and to drive a free-electron laser (FEL). To provide maximum linac availability for all uses, an additional modulator-klystron subsystem has been built,and a waveguide-switching and distribution subsystem is now under construction. The combined subsystems provide a hot spare for any of the five S-band transmitters that power the lina cand have been given the additional function of powering an rf gun test stand whenever they are not otherwise needed. Design considerations for the waveguide-switching subsystem, topology selection, timing, control, and system protection provisions are described.

  14. Plane-wave expansion method for calculating band structure of photonic crystal slabs with perfectly matched layers.

    PubMed

    Shi, Shouyuan; Chen, Caihua; Prather, Dennis W

    2004-09-01

    We present a new algorithm for calculation of the band structure of photonic crystal slabs. This algorithm combines the plane-wave expansion method with perfectly matched layers for the termination of the computational region in the direction out of the plane. In addition, the effective-medium tensor is applied to improve convergence. A general complex eigenvalue problem is then obtained. Two criteria are presented to distinguish the guided modes from the PML modes. As such, this scheme can accurately determine the band structure both above and below the light cone. The convergence of the algorithm presented has been studied. The results obtained by using this algorithm have been compared with those obtained by the finite-difference time-domain method and found to agree very well.

  15. Finite difference time domain method for calculating the band structure of a 2D photonic crystal and simulating the lensing effect

    NASA Astrophysics Data System (ADS)

    Rafiee Dastjerdi, S.; Ghanaatshoar, M.

    2013-08-01

    A finite difference time domain method based on regular Yee's algorithm in an orthogonal coordinate system is utilized to calculate the band structure of a two-dimensional square-lattice photonic crystal comprising dielectric cylinders in air background and to simulate the image formation of mentioned structure incorporating the perfectly matched layer boundary condition. By analyzing the photonic band diagram of this system, we find that the frequency region of effective negative refraction exists in the second band in near-infrared domain. In this case, electromagnetic wave propagates with a negative phase velocity and the evanescent waves can be supported to perform higher image resolution.

  16. Spatially resolved methane band photometry of Jupiter. I - Absolute reflectivity and center-to-limb variations in the 6190-, 7250-, and 8900-A bands. II - Analysis of the south equatorial belt and south tropical zone reflectivity

    NASA Technical Reports Server (NTRS)

    West, R. A.

    1979-01-01

    Spatially resolved measurements of the absolute reflectivity and center to limb variations of Jupiter in the 6190, 7250 and 8900 A methane bands and nearby continuum regions are presented and analyzed for the south equatorial belts (SEBs) and south tropical zone (STrZ). It is found that the polar hoods, equatorial zone, Red Spot and north tropical zone have highest methane reflectivities, with the temperate zones and polar regions having low reflectivity and the STrZ and SEBs having intermediate values. The data on the SEB and STrZ are analyzed in terms of diffuse reflecting-scattering and two-cloud models of the vertical distribution of aerosols in the Jovian atmosphere. To fit observations, the STrZ cloud top must have between 0.55 and 0.43 bar total pressure and optical depth between 1.5 and 2.5. The reflecting-scattering models are not suitable for the SEBs. The SEB upper cloud is deeper, cloud thickness is less and the lower cloud is deeper than in the STrZ. A forward scattering haze layer accounts for limb darkening in the continuum.

  17. CW-pumped telecom band polarization entangled photon pair generation in a Sagnac interferometer.

    PubMed

    Li, Yan; Zhou, Zhi-Yuan; Ding, Dong-Sheng; Shi, Bao-Sen

    2015-11-01

    Polarization entangled photon pair source is widely used in many quantum information processing applications such as teleportation, quantum communications, quantum computation and high precision quantum metrology. We report on the generation of a continuous-wave pumped 1550 nm polarization entangled photon pair source at telecom wavelength using a type-II periodically poled KTiOPO(4) (PPKTP) crystal in a Sagnac interferometer. Hong-Ou-Mandel (HOM) interference measurement yields signal and idler photon bandwidth of 2.4 nm. High quality of entanglement is verified by various kinds of measurements, for example two-photon interference fringes, Bell inequality and quantum states tomography. The source can be tuned over a broad range against temperature or pump power without loss of visibilities. This source will be used in our future experiments such as generation of orbital angular momentum entangled source at telecom wavelength for quantum frequency up-conversion, entanglement based quantum key distributions and many other quantum optics experiments at telecom wavelengths. PMID:26561148

  18. Quasienergy band engineering and broadband dynamic localization in photonic lattices with long-range interaction

    SciTech Connect

    Longhi, Stefano; Dreisow, Felix; Heinrich, Matthias; Pertsch, Thomas; Tuennermann, Andreas; Nolte, Stefan; Szameit, Alexander

    2010-11-15

    Polychromatic dynamic localization in tight-binding lattices with long-range interaction is theoretically proposed and experimentally demonstrated in curved-waveguide photonic lattices. Efficient suppression of discrete diffraction over the whole white-light spectral region (450-750 nm) has been demonstrated in femtosecond-laser-written triangular-waveguide lattices with first- and second-order coupling.

  19. Wide-Band Spatially Tunable Photonic Bandgap in Visible Spectral Range and Laser based on a Polymer Stabilized Blue Phase

    PubMed Central

    Lin, Jia-De; Wang, Tsai-Yen; Mo, Ting-Shan; Huang, Shuan-Yu; Lee, Chia-Rong

    2016-01-01

    This work successfully develops a largely-gradient-pitched polymer-stabilized blue phase (PSBP) photonic bandgap (PBG) device with a wide-band spatial tunability in nearly entire visible region within a wide blue phase (BP) temperature range including room temperature. The device is fabricated based on the reverse diffusion of two injected BP-monomer mixtures with a low and a high chiral concentrations and afterwards through UV-curing. This gradient-pitched PSBP can show a rainbow-like reflection appearance in which the peak wavelength of the PBG can be spatially tuned from the blue to the red regions at room temperature. The total tuning spectral range for the cell is as broad as 165 nm and covers almost the entire visible region. Based on the gradient-pitched PSBP, a spatially tunable laser is also demonstrated in this work. The temperature sensitivity of the lasing wavelength for the laser is negatively linear and approximately −0.26 nm/°C. The two devices have a great potential for use in applications of photonic devices and displays because of their multiple advantages, such as wide-band tunability, wide operated temperature range, high stability and reliability, no issue of hysteresis, no need of external controlling sources, and not slow tuning speed (mechanically). PMID:27456475

  20. Wide-Band Spatially Tunable Photonic Bandgap in Visible Spectral Range and Laser based on a Polymer Stabilized Blue Phase

    NASA Astrophysics Data System (ADS)

    Lin, Jia-De; Wang, Tsai-Yen; Mo, Ting-Shan; Huang, Shuan-Yu; Lee, Chia-Rong

    2016-07-01

    This work successfully develops a largely-gradient-pitched polymer-stabilized blue phase (PSBP) photonic bandgap (PBG) device with a wide-band spatial tunability in nearly entire visible region within a wide blue phase (BP) temperature range including room temperature. The device is fabricated based on the reverse diffusion of two injected BP-monomer mixtures with a low and a high chiral concentrations and afterwards through UV-curing. This gradient-pitched PSBP can show a rainbow-like reflection appearance in which the peak wavelength of the PBG can be spatially tuned from the blue to the red regions at room temperature. The total tuning spectral range for the cell is as broad as 165 nm and covers almost the entire visible region. Based on the gradient-pitched PSBP, a spatially tunable laser is also demonstrated in this work. The temperature sensitivity of the lasing wavelength for the laser is negatively linear and approximately ‑0.26 nm/°C. The two devices have a great potential for use in applications of photonic devices and displays because of their multiple advantages, such as wide-band tunability, wide operated temperature range, high stability and reliability, no issue of hysteresis, no need of external controlling sources, and not slow tuning speed (mechanically).

  1. Periodic layered inverse micelle multilayers with tunable photonic band gap: fabrication and application in dye-sensitized solar cells.

    PubMed

    Jang, Yoon Hee; Kim, Dong Ha

    2014-04-21

    Periodic organic-inorganic multilayer films are constructed by stepwise alternate build-up of UV-stabilized poly(styrene-block-vinylpyridine) block copolymer inverse micelles and poly(styrene-block-ethylene oxide) block copolymer layers containing inorganic moieties at the polar core blocks. The layered block copolymer inverse micelle films show strong reflective color and well-defined photonic stop bands in the entire wavelength region from visible to near IR, which can be fine-tuned by controlling the inner architectures, i.e., the periodic size of the layered structure. The layered block copolymer films are integrated into the back-side of counter electrodes as a light reflection layer and thereby an enhancement ratio of ∼11% in the cell efficiency is achieved, which can be attributed to the increased light harvesting by the sensitized dye molecules. Tailoring the inner structure of the photonic band gap multilayers, the wavelength of reflected light can be adjusted to the wavelength of dye absorption, leading to a noticeable enhancement in photocurrent and power conversion efficiency.

  2. Complete photonic band gaps and tunable self-collimation in the two-dimensional plasma photonic crystals with a new structure

    SciTech Connect

    Zhang, Hai-Feng; Ding, Guo-Wen; Li, Hai-Ming; Liu, Shao-Bin

    2015-02-15

    In this paper, the properties of complete photonic band gaps (CPBGs) and tunable self-collimation in two-dimensional plasma photonic crystals (2D PPCs) with a new structure in square lattices, whose dielectric fillers (GaAs) are inserted into homogeneous and nomagnetized plasma background are theoretically investigated by a modified plane wave expansion (PWE) method with a novel technique. The novel PWE method can be utilized to compute the dispersion curves of 2D PPCs with arbitrary-shaped cross section in any lattices. As a comparison, CPBGs of PPCs for four different configurations are numerically calculated. The computed results show that the proposed design has the advantages of achieving the larger CPBGs compared to the other three configurations. The influences of geometric parameters of filled unit cell and plasma frequency on the properties of CPBGs are studied in detail. The calculated results demonstrate that CPBGs of the proposed 2D PPCs can be easily engineered by changing those parameters, and the larger CPBGs also can be obtained by optimization. The self-collimation in such 2D PPCs also is discussed in theory under TM wave. The theoretical simulations reveal that the self-collimation phenomena can be found in the TM bands, and both the frequency range of self-collimation and the equifrequency surface contours can be tuned by the parameters as mentioned above. It means that the frequency range and direction of electromagnetic wave can be manipulated by designing, as it propagates in the proposed PPCs without diffraction. Those results can hold promise for designing the tunable applications based on the proposed PPCs.

  3. Complete photonic band gaps and tunable self-collimation in the two-dimensional plasma photonic crystals with a new structure

    NASA Astrophysics Data System (ADS)

    Zhang, Hai-Feng; Ding, Guo-Wen; Li, Hai-Ming; Liu, Shao-Bin

    2015-02-01

    In this paper, the properties of complete photonic band gaps (CPBGs) and tunable self-collimation in two-dimensional plasma photonic crystals (2D PPCs) with a new structure in square lattices, whose dielectric fillers (GaAs) are inserted into homogeneous and nomagnetized plasma background are theoretically investigated by a modified plane wave expansion (PWE) method with a novel technique. The novel PWE method can be utilized to compute the dispersion curves of 2D PPCs with arbitrary-shaped cross section in any lattices. As a comparison, CPBGs of PPCs for four different configurations are numerically calculated. The computed results show that the proposed design has the advantages of achieving the larger CPBGs compared to the other three configurations. The influences of geometric parameters of filled unit cell and plasma frequency on the properties of CPBGs are studied in detail. The calculated results demonstrate that CPBGs of the proposed 2D PPCs can be easily engineered by changing those parameters, and the larger CPBGs also can be obtained by optimization. The self-collimation in such 2D PPCs also is discussed in theory under TM wave. The theoretical simulations reveal that the self-collimation phenomena can be found in the TM bands, and both the frequency range of self-collimation and the equifrequency surface contours can be tuned by the parameters as mentioned above. It means that the frequency range and direction of electromagnetic wave can be manipulated by designing, as it propagates in the proposed PPCs without diffraction. Those results can hold promise for designing the tunable applications based on the proposed PPCs.

  4. The properties of photonic band gap and surface plasmon modes in the three-dimensional magnetized photonic crystals as the mixed polarized modes considered

    NASA Astrophysics Data System (ADS)

    Zhang, Hai-Feng; Liu, Shao-Bin; Jiang, Yu-Chi

    2015-04-01

    In this paper, the properties of photonic band gap (PBG) and surface plasmon modes in the three-dimensional (3D) magnetized plasma photonic crystals (MPPCs) with face-centered-cubic (fcc) lattices are theoretically investigated based on the plane wave expansion (PWE) method, in which the homogeneous magnetized plasma spheres are immersed in the homogeneous dielectric background, as the Voigt effects of magnetized plasma are considered (the incidence electromagnetic wave vector is perpendicular to the external magnetic field at any time). The dispersive properties of all of the EM modes are studied because the PBG is not only for the extraordinary and ordinary modes but also for the mixed polarized modes. The equations for PBGs also are theoretically deduced. The numerical results show that the PBG and a flatbands region can be observed. The effects of the dielectric constant of dielectric background, filling factor, plasma frequency and plasma cyclotron frequency (the external magnetic field) on the dispersive properties of all of the EM modes in such 3D MPPCs are investigated in detail, respectively. Theoretical simulations show that the PBG can be manipulated by the parameters as mentioned above. Compared to the conventional dielectric-air PCs with similar structure, the larger PBG can be obtained in such 3D MPPCs. It is also shown that the upper edge of flatbands region cannot be tuned by the filling factor and dielectric constant of dielectric background, but it can be manipulated by the plasma frequency and plasma cyclotron frequency.

  5. Ultrahigh-Q photonic crystal nanocavities in wide optical telecommunication bands.

    PubMed

    Terawaki, Ryo; Takahashi, Yasushi; Chihara, Masahiro; Inui, Yoshitaka; Noda, Susumu

    2012-09-24

    We have studied the feasibility of extending the operating wavelength range of high-Q silicon nanocavities above and below the 1.55 μm wavelength band, while maintaining Q factors of more than one million. We have succeeded in developing such nanocavities in the optical telecommunication bands from 1.27 μm to 1.50 μm. Very high Q values of more than two million were obtained even for the 1.30 μm band. The Q values increase proportionally to the resonant wavelength because the scattering loss decreases. We have also analyzed the influence of absorption due to surface water. We conclude that high-Q nanocavities are feasible for an even wider wavelength region including parts of the mid-infrared.

  6. Absolute Rovibrational Intensities, Self-Broadening and Self-Shift Coefficients for the X(sup 1) Sigma(+) V=3 (left arrow) V=0 Band (C-12)(O-16)

    NASA Technical Reports Server (NTRS)

    Chackerian, Charles, Jr.; Freedman, R.; Giver, L. P.; Brown, L. R.

    2001-01-01

    The rotationless transition moment squared for the x(sup 1) sigma (sup +) v=3 (left arrow) v=0 band of CO is measured to be the absolute value of R (sub 3-0) squared = 1.7127(25)x 10(exp -7) Debye squared. This value is about 8.6 percent smaller than the value assumed for HITRAN 2000. The Herman-Wallis intensity factor of this band is F=1+0.01168(11)m+0.0001065(79)m squared. The determination of self-broadening coefficients is improved with the inclusion of line narrowing; self-shifts are also reported.

  7. Photonic band gap response of structurally modified non-close-packed inverse opals by template directed multilayer atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Graugnard, Elton; Gaillot, Davy P.; King, Jeffrey S.; Summers, Christopher J.

    2006-04-01

    We report the controllable and tunable fabrication of structurally modified non-close-packed inverse shell opals using multi-layer atomic layer deposition and present a model and simulation algorithm to calculate the structural parameters critical to fabrication. This powerful, flexible and unique technique enables opal inversion, structural modification and backfilling and was applied to the fabrication of TiO II non-close-packed inverse opals. Using successive conformal backfilling it was possible to tune the Bragg peak over 600 nm and enhance the Bragg peak width by >50%. Additionally, band structure calculations, using dielectric functions approximating the true network topology, were used to predict the optical properties during the fabrication process. 3D finite-difference-time-domain results predict experimentally achievable structures with a complete band gap as large as 7.2%. Additionally, the refractive index requirement was predicted to decrease from 3.3 in an 86% infiltrated inverse shell opal to 3.0 in an optimized non-close-packed inverse shell opal. It was also shown for these structures that the complete photonic band gap peak can be statically tuned by over 70% by increasing the backfilled thickness.

  8. The two-photon absorptivity of rotational transitions in the A2 Sigma hyperon + (v prime = O) - X-2 pion (v prime prime = O) gamma band of nitric oxide

    NASA Technical Reports Server (NTRS)

    Gross, K. P.; Mckenzie, R. L.

    1982-01-01

    A predominantly single-mode pulsed dye laser system giving a well characterized spatial and temporal output suitable for absolute two-photon absorptivity measurements was used to study the NO gamma(0,0) S11 + R21 (J double prime = 7-1/2) transition. Using a calibrated induced-fluorescence technique, an absorptivity parameter of 2.8 + or - 1.4 x 10 to the minus 51st power cm to the 6th power was obtained. Relative strengths of other rotational transitions in the gamma(0,0) band were also measured and shown to compare well with predicted values in all cases except the O12 (J double prime = 10-1/2) transition.

  9. Absolute quantitation of iodine-123 epidepride kinetics using single-photon emission tomography: comparison with carbon-11 epidepride and positron emission tomography.

    PubMed

    Almeida, P; Ribeiro, M J; Bottlaender, M; Loc'h, C; Langer, O; Strul, D; Hugonnard, P; Grangeat, P; Mazière, B; Bendriem, B

    1999-12-01

    Epidepride labelled with iodine-123 is a suitable probe for the in vivo imaging of striatal and extrastriatal dopamine D2 receptors using single-photon emission tomography (SPET). Recently, this molecule has also been labelled with carbon-11. The goal of this work was to develop a method allowing the in vivo quantification of radioactivity uptake in baboon brain using SPET and to validate it using positron emission tomography (PET). SPET studies were performed in Papio anubis baboons using 123I-epidepride. Emission and transmission measurements were acquired on a dual-headed system with variable head angulation and low-energy ultra-high resolution (LEUHR) collimation. The imaging protocol consisted of one transmission measurement (24 min, heads at 90 degrees), obtained with two sliding line sources of gadolinium-153 prior to injection of 0.21-0.46 GBq of 123I-epidepride, and 12 emission measurements starting 5 min post injection. For scatter correction (SC) we used a dual-window method adapted to 123I. Collimator blurring correction (CBC) was done by deconvolution in Fourier space and attenuation correction (AT) was applied on a preliminary (CBC) filtered back-projection reconstruction using 12 iterations of a preconditioned, regularized minimal residual algorithm. For each reconstruction, a calibration factor was derived from a uniform cylinder filled with a 123I solution of a known radioactivity concentration. Calibration and baboon images were systematically built with the same reconstruction parameters. Uncorrected (UNC) and (AT), (SC + AT) and (SC + CBC + AT) corrected images were compared. PET acquisitions using 0.11-0.44 GBq of 11C-epidepride were performed on the same baboons and used as a reference. The radioactive concentrations expressed in percent of the injected dose per 100 ml (% ID/100 ml) obtained after (SC + CBC + AT) in SPET are in good agreement with those obtained with PET and 11C-epidepride. A method for the in vivo absolute quantitation of 123

  10. Fast Purcell-enhanced single photon source in 1,550-nm telecom band from a resonant quantum dot-cavity coupling

    PubMed Central

    Birowosuto, Muhammad Danang; Sumikura, Hisashi; Matsuo, Shinji; Taniyama, Hideaki; van Veldhoven, Peter J.; Nötzel, Richard; Notomi, Masaya

    2012-01-01

    High-bit-rate nanocavity-based single photon sources in the 1,550-nm telecom band are challenges facing the development of fibre-based long-haul quantum communication networks. Here we report a very fast single photon source in the 1,550-nm telecom band, which is achieved by a large Purcell enhancement that results from the coupling of a single InAs quantum dot and an InP photonic crystal nanocavity. At a resonance, the spontaneous emission rate was enhanced by a factor of 5 resulting a record fast emission lifetime of 0.2 ns at 1,550 nm. We also demonstrate that this emission exhibits an enhanced anti-bunching dip. This is the first realization of nanocavity-enhanced single photon emitters in the 1,550-nm telecom band. This coupled quantum dot cavity system in the telecom band thus provides a bright high-bit-rate non-classical single photon source that offers appealing novel opportunities for the development of a long-haul quantum telecommunication system via optical fibres. PMID:22432053

  11. Angle-dependent study of a direct optical transition in the sp bands of Ag(111) by one- and two-photon photoemission

    NASA Astrophysics Data System (ADS)

    Winkelmann, Aimo; Sametoglu, Vahit; Zhao, Jin; Kubo, Atsushi; Petek, Hrvoje

    2007-11-01

    We have measured angle-dependent photoemission spectra for one-photon and two-photon excitation from Ag(111). The observed dispersion of the sp -band transition of Ag(111) can be reproduced using a nearly-free-electron model for the initial and final states involved. The observed dispersion agrees with the known band structure. We illustrate how the strong refraction of low-energy electrons becomes a limiting factor to obtain quantitative band-structure information. Conversely, low-energy electrons of a well-defined direct optical interband transition can provide a sensitive probe of the inner potential. We observe asymmetric two-photon photoelectron intensity distributions with respect to detection along the surface normal. These intensity distributions can be well described by a phenomenological model which employs the Fresnel equations to calculate the electric field components of the incident radiation inside the sample. Very good agreement is found using tabulated optical constants and a momentum matrix element, which is oriented along the surface normal. In contrast, the observed intensity distribution for one-photon photoemission from Ag(111) does not fit the simple Fresnel model. We interpret this as the influence of surface photoemission. By comparison to Cu(001), we show that the expected intensity distributions of the Fresnel model for one-photon photoemission and two-photon photoemission are valid for an orientation of the momentum matrix element along the surface normal if the influence of additional effects like surface photoemission can be neglected.

  12. Field Demonstration of Photonic Antenna Remoting at X-Band in the NASA Deep Space Network

    NASA Technical Reports Server (NTRS)

    Yao, X.; Lutes, G.; Logan, R.; Maleki, L.

    1994-01-01

    We report on the successful demonstration of antenna remoting at X-band using a low phase noise and high dynamic range fiber optic link in an operating antenna receiving system, while tracking Magellan spacecraft. The insertion of the fiber link into the existing system adds no observable degradation in noise temperature to the system. We compare the experimental results with our theoretical predictions of degradations in noise temperature and dynamic range of the system caused by the insertion of the fiber link.

  13. Controlling multi-wave mixing signals via photonic band gap of electromagnetically induced absorption grating in atomic media.

    PubMed

    Zhang, Yiqi; Wu, Zhenkun; Yao, Xin; Zhang, Zhaoyang; Chen, Haixia; Zhang, Huaibin; Zhang, Yanpeng

    2013-12-01

    We experimentally demonstrate dressed multi-wave mixing (MWM) and the reflection of the probe beam due to electromagnetically induced absorption (EIA) grating can coexist in a five-level atomic ensemble. The reflection is derived from the photonic band gap (PBG) of EIA grating, which is much broader than the PBG of EIT grating. Therefore, EIA-type PBG can reflect more energy from probe than EIT-type PBG does, which can effectively affect the MWM signal. The EIA-type as well as EIT-type PBG can be controlled by multiple parameters including the frequency detunings, propagation angles and powers of the involved light fields. Also, the EIA-type PBG by considering both the linear and third-order nonlinear refractive indices is also investigated. The theoretical analysis agrees well with the experimental results. This investigation has potential applications in all-optical communication and information processing.

  14. Higher order mode damping in a five-cell superconducting rf cavity with a photonic band gap coupler cell

    NASA Astrophysics Data System (ADS)

    Arsenyev, Sergey A.; Temkin, Richard J.; Shchegolkov, Dmitry Yu.; Simakov, Evgenya I.; Boulware, Chase H.; Grimm, Terry L.; Rogacki, Adam R.

    2016-08-01

    We present a study of higher order mode (HOM) damping in the first multicell superconducting radio-frequency (SRF) cavity with a photonic band gap (PBG) coupler cell. Achieving higher average beam currents is particularly desirable for future light sources and particle colliders based on SRF energy-recovery linacs (ERLs). Beam current in ERLs is limited by the beam breakup instability, caused by parasitic HOMs interacting with the beam in accelerating cavities. A PBG cell incorporated in an accelerating cavity can reduce the negative effect of HOMs by providing a frequency selective damping mechanism, thus allowing significantly higher beam currents. The five-cell cavity with a PBG cell was designed and optimized for HOM damping. Monopole and dipole HOMs were simulated. The SRF cavity was fabricated and tuned. External quality factors for some HOMs were measured in a cold test. The measurements agreed well with the simulations.

  15. A photonic band-gap resonator to facilitate GHz-frequency conductivity experiments in pulsed magnetic fields

    NASA Astrophysics Data System (ADS)

    McDonald, R. D.; Singleton, J.; Goddard, P. A.; Harrison, N.; Mielke, C. H.

    2006-08-01

    We describe instrumentation designed to perform millimeter-wave conductivity measurements in pulsed high magnetic fields at low temperatures. The main component of this system is an entirely nonmetallic microwave resonator. The resonator utilizes periodic dielectric arrays (photonic band-gap structures) to confine the radiation, such that the resonant modes have a high Q factor, and the system possesses sufficient sensitivity to measure small samples within the duration of a magnet pulse. As well as measuring the sample conductivity to probe orbital physics in metallic systems, this technique can detect the sample permittivity and permeability allowing measurement of spin physics in insulating systems. We demonstrate the system performance in pulsed magnetic fields with both electron paramagnetic resonance experiments and conductivity measurements of correlated electron systems.

  16. Octave-wide photonic band gap in three-dimensional plasmonic Bragg structures and limitations of radiative coupling

    PubMed Central

    Taubert, Richard; Dregely, Daniel; Stroucken, Tineke; Christ, Andre; Giessen, Harald

    2012-01-01

    Radiative coupling between oscillators is one of the most fundamental subjects of research in optics, where particularly a Bragg-type arrangement is of interest and has already been applied to atoms and excitons in quantum wells. Here we explore this arrangement in a plasmonic structure. We observe the emergence of an octave-wide photonic band gap in the optical regime. Compared with atomic or excitonic systems, the coupling efficiency of the particle plasmons utilized here is several orders of magnitude larger and widely tunable by changing the size and geometry of the plasmonic nanowires. We are thus able to explore the regime where the coupling distance is even limited by the large radiative decay rate of the oscillators. This Bragg-stacked coupling scheme will open a new route for future plasmonic applications such as far-field coupling to quantum emitters without quenching, plasmonic cavity structures and plasmonic distributed gain schemes for spasers. PMID:22353721

  17. Optimizing the configuration of a superconducting photonic band gap accelerator cavity to increase the maximum achievable gradients

    NASA Astrophysics Data System (ADS)

    Simakov, Evgenya I.; Kurennoy, Sergey S.; O'Hara, James F.; Olivas, Eric R.; Shchegolkov, Dmitry Yu.

    2014-02-01

    We present a design of a superconducting rf photonic band gap (SRF PBG) accelerator cell with specially shaped rods in order to reduce peak surface magnetic fields and improve the effectiveness of the PBG structure for suppression of higher order modes (HOMs). The ability of PBG structures to suppress long-range wakefields is especially beneficial for superconducting electron accelerators for high power free-electron lasers (FELs), which are designed to provide high current continuous duty electron beams. Using PBG structures to reduce the prominent beam-breakup phenomena due to HOMs will allow significantly increased beam-breakup thresholds. As a result, there will be possibilities for increasing the operation frequency of SRF accelerators and for the development of novel compact high-current accelerator modules for the FELs.

  18. Compact photonic crystal circulator with flat-top transmission band created by cascading magneto-optical resonance cavities.

    PubMed

    Wang, Qiong; Ouyang, Zhengbiao; Lin, Mi; Liu, Qiang

    2015-11-20

    A new type of compact three-port circulator with flat-top transmission band (FTTB) in a two-dimensional photonic crystal has been proposed, through coupling the cascaded magneto-optical resonance cavities to waveguides. The coupled-mode theory is applied to investigate the coupled structure and analyze the condition to achieve FTTB. According to the theoretical analysis, the structure is further optimized to ensure that the condition for achieving FTTB can be satisfied for both cavity-cavity coupling and cavity-waveguide coupling. Through the finite-element method, it is demonstrated that the design can realize a high quality, nonreciprocal circulating propagation of waves with an insertion loss of 0.023 dB and an isolation of 23.3 dB, covering a wide range of operation frequency. Such a wideband circulator has potential applications in large-scale integrated photonic circuits for guiding or isolating harmful optical reflections from load elements.

  19. Nonaqueous sol-gel chemistry applied to atomic layer deposition: tuning of photonic band gap properties of silica opals.

    PubMed

    Marichy, Catherine; Dechézelles, Jean-Francois; Willinger, Marc-Georg; Pinna, Nicola; Ravaine, Serge; Vallée, Renaud

    2010-05-01

    Combining both electromagnetic simulations and experiments, it is shown that the photonic pseudo band gap (PPBG) exhibited by a silica opal can be fully controlled by Atomic Layer Deposition (ALD) of titania into the pores of the silica spheres constituting the opal. Different types of opals were assembled by the Langmuir-Blodgett technique: homogeneous closed packed structures set up of, respectively, 260 and 285 nm silica spheres, as well as opal heterostructures consisting of a monolayer of 430 nm silica spheres embedded within 10 layers of 280 nm silica spheres. For the stepwise infiltration of the opals with titania, titanium isopropoxide and acetic acid were used as metal and oxygen sources, in accordance with a recently published non-aqueous approach to ALD. A shift of the direct PPBG, its disappearance, and the subsequent appearance and shifting of the inverse PPBG are observed as the opal is progressively filled. The close agreement between simulated and experimental results is striking, and promising in terms of predicting the properties of advanced photonic materials. Moreover, this work demonstrates that the ALD process is rather robust and can be applied to the coating of complex nanostructures.

  20. High-depth-resolution 3-dimensional radar-imaging system based on a few-cycle W-band photonic millimeter-wave pulse generator.

    PubMed

    Tseng, Tzu-Fang; Wun, Jhih-Min; Chen, Wei; Peng, Sui-Wei; Shi, Jin-Wei; Sun, Chi-Kuang

    2013-06-17

    We demonstrate that a near-single-cycle photonic millimeter-wave short-pulse generator at W-band is capable to provide high spatial resolution three-dimensional (3-D) radar imaging. A preliminary study indicates that 3-D radar images with a state-of-the-art ranging resolution of around 1.2 cm at the W-band can be achieved.

  1. Absolute Rovibrational Intensities for the Chi(sup 1)Sigma(sup +) v=3 <-- 0 Band of (12)C(16)O Obtained with Kitt Peak and BOMEM FTS Instruments

    NASA Technical Reports Server (NTRS)

    Chackerian, Charles, Jr.; Kshirsagar, R. J.; Giver, L. P.; Brown, L. R.; Condon, Estelle P. (Technical Monitor)

    1999-01-01

    This work was initiated to compare absolute line intensities retrieved with the Kitt Peak FTS (Fourier Transform Spectrometer) and Ames BOMEM FTS. Since thermal contaminations can be a problem using the BOMEM instrument if proper precautions are not taken it was thought that measurements done at 6300 per cm would more easily result in satisfactory intercomparisons. Very recent measurements of the CO 3 <-- 0 band fine intensities confirms results reported here that the intensities listed in HITRAN (High Resolution Molecular Absorption Database) for this band are on the order of six to seven percent too low. All of the infrared intensities in the current HITRAN tabulation are based on the electric dipole moment function reported fifteen years ago. The latter in turn was partly based on intensities for the 3 <-- 0 band reported thirty years ago. We have, therefore, redetermined the electric dipole moment function of ground electronic state CO.

  2. Micro-metric electronic patterning of a topological band structure using a photon beam

    PubMed Central

    Frantzeskakis, E.; De Jong, N.; Zwartsenberg, B.; Huang, Y. K.; Bay, T. V.; Pronk, P.; Van Heumen, E.; Wu, D.; Pan, Y.; Radovic, M.; Plumb, N. C.; Xu, N.; Shi, M.; De Visser, A.; Golden, M. S.

    2015-01-01

    In an ideal 3D topological insulator (TI), the bulk is insulating and the surface conducting due to the existence of metallic states that are localized on the surface; these are the topological surface states. Quaternary Bi-based compounds of Bi2−xSbxTe3−ySey with finely-tuned bulk stoichiometries are good candidates for realizing ideal 3D TI behavior due to their bulk insulating character. However, despite its insulating bulk in transport experiments, the surface region of Bi2−xSbxTe3−ySey crystals cleaved in ultrahigh vacuum also exhibits occupied states originating from the bulk conduction band. This is due to adsorbate-induced downward band-bending, a phenomenon known from other Bi-based 3D TIs. Here we show, using angle-resolved photoemission, how an EUV light beam of moderate flux can be used to exclude these topologically trivial states from the Fermi level of Bi1.46Sb0.54Te1.7Se1.3 single crystals, thereby re-establishing the purely topological character of the low lying electronic states of the system. We furthermore prove that this process is highly local in nature in this bulk-insulating TI, and are thus able to imprint structures in the spatial energy landscape at the surface. We illustrate this by ‘writing’ micron-sized letters in the Dirac point energy of the system. PMID:26543011

  3. Micro-metric electronic patterning of a topological band structure using a photon beam.

    PubMed

    Frantzeskakis, E; De Jong, N; Zwartsenberg, B; Huang, Y K; Bay, T V; Pronk, P; Van Heumen, E; Wu, D; Pan, Y; Radovic, M; Plumb, N C; Xu, N; Shi, M; De Visser, A; Golden, M S

    2015-01-01

    In an ideal 3D topological insulator (TI), the bulk is insulating and the surface conducting due to the existence of metallic states that are localized on the surface; these are the topological surface states. Quaternary Bi-based compounds of Bi(2-x)Sb(x)Te(3-y)Se(y) with finely-tuned bulk stoichiometries are good candidates for realizing ideal 3D TI behavior due to their bulk insulating character. However, despite its insulating bulk in transport experiments, the surface region of Bi(2-x)Sb(x)Te(3-y)Se(y) crystals cleaved in ultrahigh vacuum also exhibits occupied states originating from the bulk conduction band. This is due to adsorbate-induced downward band-bending, a phenomenon known from other Bi-based 3D TIs. Here we show, using angle-resolved photoemission, how an EUV light beam of moderate flux can be used to exclude these topologically trivial states from the Fermi level of Bi1.46Sb0.54Te1.7Se1.3 single crystals, thereby re-establishing the purely topological character of the low lying electronic states of the system. We furthermore prove that this process is highly local in nature in this bulk-insulating TI, and are thus able to imprint structures in the spatial energy landscape at the surface. We illustrate this by 'writing' micron-sized letters in the Dirac point energy of the system. PMID:26543011

  4. Measurement of the resonant polaron effect in the Reststrahlen band of GaAs:Si using far-infrared two-photon excitation

    SciTech Connect

    Wenckebach, W.Th.; Planken, P.C.M.; Son, P.C. van

    1995-12-31

    We present the results of photoconductivity measurements of the resonant electron-phonon interaction in the middle of the Reststrahlen band using two-photon excitation with intense picosecond pulses with frequency around 143 cm{sup -1} (70 {mu}m). We use two photons rather than a single photon for the excitation of the resonant-polaron to avoid the problems of strong reflection and dielectric artifacts encountered in direct single-photon excitation in the Reststrahlen band. The sample is a 10 {mu}m thick Si-doped GaAs epitaxial layer on a 400 {mu}m semi-insulating GaAs substrate. The electronic levels of the Si shallow donor can be tuned by the application of a magnetic field. Intense tunable picosecond pulses with a frequency of around 143 cm{sup -1} from the Dutch free-electron laser FELIX are weakly focussed onto the sample, which is kept at 8 K. Electrons excited to the 3d{sup +2} state via the electric-dipole allowed two-photon transition out of the 1s{sub 0-} ground state, decay to the conduction band and give rise to an increase in the photoconductivity. The figure shows the energy-peak position of the 3d{sup +2} transition thus obtained as a function of the magnetic-field strength. The figure clearly shows the avoided crossing around the LO-phonon energy where the coupling shows the avoided crossing around the LO-phonon energy where the coupling between the 3d{sup +2} state and the LO phonon is strongest. Note that the data between 267 cm{sup -1} and 296 cm{sup -1} are extremely difficult to obtain with single-photon excitation because of their position in the middle of the Reststrahlen band.

  5. Switching of the photonic band gap in three-dimensional film photonic crystals based on opal-VO{sub 2} composites in the 1.3-1.6 {mu}m spectral range

    SciTech Connect

    Pevtsov, A. B. Grudinkin, S. A.; Poddubny, A. N.; Kaplan, S. F.; Kurdyukov, D. A.; Golubev, V. G.

    2010-12-15

    The parameters of three-dimensional photonic crystals based on opal-VO{sub 2} composite films in the 1.3-1.6 {mu}m spectral range important for practical applications (Telecom standard) are numerically calculated. For opal pores, the range of filling factors is established (0.25-0.6) wherein the composite exhibits the properties of a three-dimensional insulator photonic crystal. On the basis of the opal-VO{sub 2} composites, three-dimensional photonic film crystals are synthesized with specified parameters that provide a maximum shift of the photonic band gap in the vicinity of the wavelength {approx}1.5 {mu}m ({approx}170 meV) at the semiconductor-metal transition in VO{sub 2}.

  6. Absolute intensities and self-, N2-, and air-broadened Lorentz halfwidths for selected lines in the nu3 band of (C-12)H3D from measurements with a tunable diode laser spectrometer

    NASA Technical Reports Server (NTRS)

    Malathy Devi, V.; Benner, D. C.; Rinsland, C. P.; Smith, M. A. H.; Thakur, K. B.

    1986-01-01

    Absolute intensities and self-, air- and N2-broadened half-widths have been determined for the first time for individual lines in the nu3(A1) band of (C-12)H3D near 7.6 microns from measurements of individual vibration-rotation lines using a tunable diode laser spectrometer. The intensity measurements are believed to be accurate to within three percent. Within experimental uncertainties, equal broadening efficiencies are found for both air and nitrogen. Self-broadened half-widths determined for three transitions yield an average half-width value of 0.803 + or -0.0010/cm/atm at 296 K.

  7. Temperature dependence of beat-length and confinement loss in an air-core photonic band-gap fiber

    NASA Astrophysics Data System (ADS)

    Xu, Zhenlong; Li, Xuyou; Hong, Yong; Liu, Pan; Yang, Hanrui; Ling, Weiwei

    2016-05-01

    The temperature dependence of polarization-maintaining (PM) property and loss in a highly-birefringent air-core photonic band-gap fiber (PBF) is investigated. The effects of temperature variation on the effective index, beat-length and confinement loss are studied numerically by using the full-vector finite element method (FEM). It is found that, the PM property of this PBF is insensitive to the temperature, and the temperature-dependent beat-length coefficient can be as low as 2.86×10-8 m/°C, which is typically 200 times less than those of conventional panda fibers, the PBF has a stable confinement loss of 0.01 dB/m over the temperature range of -30 to 20 °C for the slow axis at the wavelength of 1.55 μm. The PBF with ultra-low temperature-dependent PM property and low loss can reduce the thermally induced polarization instability apparently in interferometric applications such as resonant fiber optic gyroscope (RFOG), optical fiber sensors, and so on.

  8. Effects of electron beam parameters and velocity spread on radio frequency output of a photonic band gap cavity gyrotron oscillator

    SciTech Connect

    Singh, Ashutosh; Jain, P. K.

    2015-09-15

    In this paper, the effects of electron beam parameters and velocity spread on the RF behavior of a metallic photonic band gap (PBG) cavity gyrotron operating at 35 GHz with TE{sub 041}–like mode have been theoretically demonstrated. PBG cavity is used here to achieve a single mode operation of the overmoded cavity. The nonlinear time-dependent multimode analysis has been used to observe the beam-wave interaction behavior of the PBG cavity gyrotron, and a commercially available PIC code “CST Particle Studio” has been reconfigured to obtain 3D simulation results in order to validate the analytical values. The output power for this typical PBG gyrotron has been obtained ∼108 kW with ∼15.5% efficiency in a well confined TE{sub 041}–like mode, while all other competing modes have significantly low values of power output. The output power and efficiency of a gyrotron depend highly on the electron beam parameters and velocity spread. The influence of several electron beam parameters, e.g., beam voltage, beam current, beam velocity pitch factor, and DC magnetic field, on the PBG gyrotron operations has been investigated. This study would be helpful in optimising the electron beam parameters and estimating accurate RF output power of the high frequency PBG cavity based gyrotron oscillators.

  9. Plant lighting system with five wavelength-band light-emitting diodes providing photon flux density and mixing ratio control

    PubMed Central

    2012-01-01

    Background Plant growth and development depend on the availability of light. Lighting systems therefore play crucial roles in plant studies. Recent advancements of light-emitting diode (LED) technologies provide abundant opportunities to study various plant light responses. The LED merits include solidity, longevity, small element volume, radiant flux controllability, and monochromaticity. To apply these merits in plant light response studies, a lighting system must provide precisely controlled light spectra that are useful for inducing various plant responses. Results We have developed a plant lighting system that irradiated a 0.18 m2 area with a highly uniform distribution of photon flux density (PFD). The average photosynthetic PFD (PPFD) in the irradiated area was 438 micro-mol m–2 s–1 (coefficient of variation 9.6%), which is appropriate for growing leafy vegetables. The irradiated light includes violet, blue, orange-red, red, and far-red wavelength bands created by LEDs of five types. The PFD and mixing ratio of the five wavelength-band lights are controllable using a computer and drive circuits. The phototropic response of oat coleoptiles was investigated to evaluate plant sensitivity to the light control quality of the lighting system. Oat coleoptiles irradiated for 23 h with a uniformly distributed spectral PFD (SPFD) of 1 micro-mol m–2 s–1 nm–1 at every peak wavelength (405, 460, 630, 660, and 735 nm) grew almost straight upwards. When they were irradiated with an SPFD gradient of blue light (460 nm peak wavelength), the coleoptiles showed a phototropic curvature in the direction of the greater SPFD of blue light. The greater SPFD gradient induced the greater curvature of coleoptiles. The relation between the phototropic curvature (deg) and the blue-light SPFD gradient (micro-mol m–2 s–1 nm–1 m–1) was 2 deg per 1 micro-mol m–2 s–1 nm–1 m–1. Conclusions The plant lighting system, with a computer with a graphical user interface

  10. Band structure of a 2D photonic crystal based on ferrofluids of Co(1-x)Znx Fe2O4 nanoparticles under perpendicular applied magnetic field

    NASA Astrophysics Data System (ADS)

    Lopez, Javier; Gonzalez, Luz Esther; Quinonez, Mario; Porras, Nelson; Zambrano, Gustavo; Gomez, Maria Elena

    2014-03-01

    Using a ferrfluid of cobalt-zinc ferrite nanoparticles Co(1 - x)ZnxFe2O4 coated with oleic acid and suspended in ethanol, we have fabricated a 2D photonic crystal (PC) by the application of an external magnetic field perpendicular to the plane of the ferrofluid. The 2D PC is made by rods of nanoparticles organized in a hexagonal structure. By means of the plane-wave expansion method, we study its photonic band structure (PBS) which depends on the effective permittivity and on the area ratio of the liquid phase. Additionaly, taking into account the Maxwell-Garnett theory we calculated the effective permittivity of the rods. We have found that the effective refractive index of the ferrofluid increases with its magnetization. Using these results we calculate the band structure of the photonic crystal at different applied magnetic fields, finding that the increase of the applied magnetic field shifts the band structure to lower frequencies with the appearance of more band gaps. Departamento de Física, Universidad del Valle, A.A. 25360, Cali, Colombia

  11. Cascaded Mach-Zehnder wavelength filters in silicon photonics for low loss and flat pass-band WDM (de-)multiplexing.

    PubMed

    Horst, Folkert; Green, William M J; Assefa, Solomon; Shank, Steven M; Vlasov, Yurii A; Offrein, Bert Jan

    2013-05-20

    We present 1-to-8 wavelength (de-)multiplexer devices based on a binary tree of cascaded Mach-Zehnder-like lattice filters, and manufactured using a 90 nm CMOS-integrated silicon photonics technology. We demonstrate that these devices combine a flat pass-band over more than 50% of the channel spacing with low insertion loss of less than 1.6 dB, and have a small device size of approximately 500 × 400 µm. This makes this type of filters well suited for application as WDM (de-)multiplexer in silicon photonics transceivers for optical data communication in large scale computer systems.

  12. Cascaded Mach-Zehnder wavelength filters in silicon photonics for low loss and flat pass-band WDM (de-)multiplexing.

    PubMed

    Horst, Folkert; Green, William M J; Assefa, Solomon; Shank, Steven M; Vlasov, Yurii A; Offrein, Bert Jan

    2013-05-20

    We present 1-to-8 wavelength (de-)multiplexer devices based on a binary tree of cascaded Mach-Zehnder-like lattice filters, and manufactured using a 90 nm CMOS-integrated silicon photonics technology. We demonstrate that these devices combine a flat pass-band over more than 50% of the channel spacing with low insertion loss of less than 1.6 dB, and have a small device size of approximately 500 × 400 µm. This makes this type of filters well suited for application as WDM (de-)multiplexer in silicon photonics transceivers for optical data communication in large scale computer systems. PMID:23736388

  13. Band alignment and photon extraction studies of Na-doped MgZnO/Ga-doped ZnO heterojunction for light-emitter applications

    NASA Astrophysics Data System (ADS)

    Pandey, Sushil Kumar; Awasthi, Vishnu; Sengar, Brajendra Singh; Garg, Vivek; Sharma, Pankaj; Kumar, Shailendra; Mukherjee, C.; Mukherjee, Shaibal

    2015-10-01

    Ultraviolet photoelectron spectroscopy is carried out to measure the energy discontinuity at the interface of p-type Na-doped MgZnO (NMZO)/n-type Ga-doped ZnO (GZO) heterojunction grown by dual ion beam sputtering. The offset values at valence band and conduction band of NMZO/GZO heterojunction are calculated to be 1.93 and -2.36 eV, respectively. The p-type conduction in NMZO film has been confirmed by Hall measurement and band structure. Moreover, the effect of Ar+ ion sputtering on the valence band onset values of NMZO and GZO thin films has been investigated. This asymmetric waveguide structure formed by the lower refractive index of GZO than that of NMZO indicates that easy extraction of photons generated in GZO through the NMZO layer into free space. The asymmetric waveguide structure has potential applications to produce ZnO-based light emitters with high extraction efficiency.

  14. Absolute Summ

    NASA Astrophysics Data System (ADS)

    Phillips, Alfred, Jr.

    Summ means the entirety of the multiverse. It seems clear, from the inflation theories of A. Guth and others, that the creation of many universes is plausible. We argue that Absolute cosmological ideas, not unlike those of I. Newton, may be consistent with dynamic multiverse creations. As suggested in W. Heisenberg's uncertainty principle, and with the Anthropic Principle defended by S. Hawking, et al., human consciousness, buttressed by findings of neuroscience, may have to be considered in our models. Predictability, as A. Einstein realized with Invariants and General Relativity, may be required for new ideas to be part of physics. We present here a two postulate model geared to an Absolute Summ. The seedbed of this work is part of Akhnaton's philosophy (see S. Freud, Moses and Monotheism). Most important, however, is that the structure of human consciousness, manifest in Kenya's Rift Valley 200,000 years ago as Homo sapiens, who were the culmination of the six million year co-creation process of Hominins and Nature in Africa, allows us to do the physics that we do. .

  15. Effect of temperature on terahertz photonic and omnidirectional band gaps in one-dimensional quasi-periodic photonic crystals composed of semiconductor InSb.

    PubMed

    Singh, Bipin K; Pandey, Praveen C

    2016-07-20

    Engineering of thermally tunable terahertz photonic and omnidirectional bandgaps has been demonstrated theoretically in one-dimensional quasi-periodic photonic crystals (PCs) containing semiconductor and dielectric materials. The considered quasi-periodic structures are taken in the form of Fibonacci, Thue-Morse, and double periodic sequences. We have shown that the photonic and omnidirectional bandgaps in the quasi-periodic structures with semiconductor constituents are strongly depend on the temperature, thickness of the constituted semiconductor and dielectric material layers, and generations of the quasi-periodic sequences. It has been found that the number of photonic bandgaps increases with layer thickness and generation of the quasi-periodic sequences. Omnidirectional bandgaps in the structures have also been obtained. Results show that the bandwidths of photonic and omnidirectional bandgaps are tunable by changing the temperature and lattice parameters of the structures. The generation of quasi-periodic sequences can also change the properties of photonic and omnidirectional bandgaps remarkably. The frequency range of the photonic and omnidirectional bandgaps can be tuned by the change of temperature and layer thickness of the considered quasi-periodic structures. This work will be useful to design tunable terahertz PC devices. PMID:27463924

  16. A program for calculating photonic band structures, Green's functions and transmission/reflection coefficients using a non-orthogonal FDTD method

    NASA Astrophysics Data System (ADS)

    Ward, A. J.; Pendry, J. B.

    2000-06-01

    In this paper we present an updated version of our ONYX program for calculating photonic band structures using a non-orthogonal finite difference time domain method. This new version employs the same transparent formalism as the first version with the same capabilities for calculating photonic band structures or causal Green's functions but also includes extra subroutines for the calculation of transmission and reflection coefficients. Both the electric and magnetic fields are placed onto a discrete lattice by approximating the spacial and temporal derivatives with finite differences. This results in discrete versions of Maxwell's equations which can be used to integrate the fields forwards in time. The time required for a calculation using this method scales linearly with the number of real space points used in the discretization so the technique is ideally suited to handling systems with large and complicated unit cells.

  17. Design optimization of a low-loss and wide-band sharp 120° waveguide bend in 2D photonic crystals

    NASA Astrophysics Data System (ADS)

    Yuan, Jianhua; Yang, Jian; Shi, Dan; Ai, Wenbao; Shuai, Tianping

    2016-05-01

    For two dimensional photonic crystals containing finite cylinders on triangle lattice, a 120° waveguide bend with low-loss and wide-band is obtained in this paper. The optimal process can be divided into two steps: firstly, a conventional waveguide bend can be introduced by maximizing the photonic bandgap; then further optimization involves shifting the position and modifying the radius of only one air hole near the bend. An optimization problem at a given frequency or over a frequency range needs to be solved. It depends on both the field solutions obtained by using the finite element method and the optimization of photonic bandgap obtained by using the plane wave expansion method. With the proposed optimal technique, the result of our optimized design for sharp 120° waveguide bends shows that an obvious low-loss transmission at wavelength 1550 nm can be observed and the maximum value of objective function is able to be rapidly obtained.

  18. Application of Novel High Order Time Domain Vector Finite Element Method to Photonic Band-Gap Waveguides

    SciTech Connect

    Rieben, R; White, D; Rodrigue, G

    2004-01-13

    In this paper we motivate the use of a novel high order time domain vector finite element method that is of arbitrary order accuracy in space and up to 5th order accurate in time; and in particular, we apply it to the case of photonic band-gap (PBG) structures. Such structures have been extensively studied in the literature with several practical applications; in particular, for the low loss transmission of electromagnetic energy around sharp 90 degree bends [1]. Typically, such structures are simulated via a numerical solution of Maxwell's equations either in the frequency domain or directly in the time domain over a computational grid. The majority of numerical simulations performed for such structures make use of the widely popular finite difference time domain (FDTD) method [2], where the time dependent electric and magnetic fields are discretized over a ''dual'' grid to second order accuracy in space and time. However, such methods do not generalize to unstructured, non-orthogonal grids or to higher order spatial discretization schemes. To simulate more complicated structures with curved boundaries, such as the structure of [3], a cell based finite element method with curvilinear elements is preferred over standard stair-stepped Cartesian meshes; and to more efficiently reduce the effects of numerical dispersion, a higher order method is highly desirable. In this paper, the high order basis functions of [5] are used in conjunction with the high order energy conserving symplectic time integration algorithms of [6] resulting in a high order, fully mimetic, mixed vector finite element method.

  19. High-quality photonic crystals with a nearly complete band gap obtained by direct inversion of woodpile templates with titanium dioxide

    PubMed Central

    Marichy, Catherine; Muller, Nicolas; Froufe-Pérez, Luis S.; Scheffold, Frank

    2016-01-01

    Photonic crystal materials are based on a periodic modulation of the dielectric constant on length scales comparable to the wavelength of light. These materials can exhibit photonic band gaps; frequency regions for which the propagation of electromagnetic radiation is forbidden due to the depletion of the density of states. In order to exhibit a full band gap, 3D PCs must present a threshold refractive index contrast that depends on the crystal structure. In the case of the so-called woodpile photonic crystals this threshold is comparably low, approximately 1.9 for the direct structure. Therefore direct or inverted woodpiles made of high refractive index materials like silicon, germanium or titanium dioxide are sought after. Here we show that, by combining multiphoton lithography and atomic layer deposition, we can achieve a direct inversion of polymer templates into TiO2 based photonic crystals. The obtained structures show remarkable optical properties in the near-infrared region with almost perfect specular reflectance, a transmission dip close to the detection limit and a Bragg length comparable to the lattice constant. PMID:26911540

  20. High-quality photonic crystals with a nearly complete band gap obtained by direct inversion of woodpile templates with titanium dioxide

    NASA Astrophysics Data System (ADS)

    Marichy, Catherine; Muller, Nicolas; Froufe-Pérez, Luis S.; Scheffold, Frank

    2016-02-01

    Photonic crystal materials are based on a periodic modulation of the dielectric constant on length scales comparable to the wavelength of light. These materials can exhibit photonic band gaps; frequency regions for which the propagation of electromagnetic radiation is forbidden due to the depletion of the density of states. In order to exhibit a full band gap, 3D PCs must present a threshold refractive index contrast that depends on the crystal structure. In the case of the so-called woodpile photonic crystals this threshold is comparably low, approximately 1.9 for the direct structure. Therefore direct or inverted woodpiles made of high refractive index materials like silicon, germanium or titanium dioxide are sought after. Here we show that, by combining multiphoton lithography and atomic layer deposition, we can achieve a direct inversion of polymer templates into TiO2 based photonic crystals. The obtained structures show remarkable optical properties in the near-infrared region with almost perfect specular reflectance, a transmission dip close to the detection limit and a Bragg length comparable to the lattice constant.

  1. A 0.2-0.5 THz single-band heterodyne receiver based on a photonic local oscillator and a superconductor-insulator-superconductor mixer

    NASA Astrophysics Data System (ADS)

    Kohjiro, Satoshi; Kikuchi, Kenichi; Maezawa, Masaaki; Furuta, Tomofumi; Wakatsuki, Atsushi; Ito, Hiroshi; Shimizu, Naofumi; Nagatsuma, Tadao; Kado, Yuichi

    2008-09-01

    We have demonstrated that a superconductor-insulator-superconductor (SIS) mixer pumped by a photonic local oscillator (LO) covers the whole frequency range of 0.2-0.5THz. In the bandwidth of 74% of the center frequency, this single-band receiver exhibits noise temperature of TRX⩽20hf/kB, where h is Planck's constant, f is the frequency, and kB is Boltzmann's constant. Resultant TRX is almost equal to TRX of the identical SIS mixer pumped by three conventional frequency-multiplier-based LOs which share the 0.2-0.5THz band. This technique will contribute to simple, wide-band, and low-noise heterodyne receivers in the terahertz region.

  2. Accurate absolute reference frequencies from 1511 to 1545 nm of the {nu}{sub 1}+{nu}{sub 3} band of {sup 12}C{sub 2}H{sub 2} determined with laser frequency comb interval measurements

    SciTech Connect

    Madej, Alan A.; Alcock, A. John; Czajkowski, Andrzej; Bernard, John E.; Chepurov, Sergei

    2006-10-15

    Absolute frequency measurements, with uncertainties as low as 2 kHz (1x10{sup -11}), are presented for the {nu}{sub 1}+{nu}{sub 3} band of {sup 12}C{sub 2}H{sub 2} at 1.5 {mu}m (194-198 THz). The measurements were made using cavity-enhanced, diode-laser-based saturation spectroscopy. With one laser system stabilized to the P(16) line of {sup 13}C{sub 2}H{sub 2} and a system stabilized to the line in {sup 12}C{sub 2}H{sub 2} whose frequency was to be determined, a Cr:YAG laser-based frequency comb was employed to measure the frequency intervals. The systematic uncertainty is notably reduced relative to that of previous studies, and the region of measured lines has been extended. Improved molecular constants are obtained.

  3. Accurate absolute frequencies of the {nu}{sub 1}+{nu}{sub 3} band of {sup 13}C{sub 2}H{sub 2} determined using an infrared mode-locked Cr:YAG laser frequency comb

    SciTech Connect

    Madej, Alan A.; Bernard, John E.; John Alcock, A.; Czajkowski, Andrzej; Chepurov, Sergei

    2006-04-15

    Absolute frequency measurements, with up to 1x10{sup -11} level accuracies, are presented for 60 lines of the P and R branches for the {nu}{sub 1}+{nu}{sub 3} band of {sup 13}C{sub 2}H{sub 2} at 1.5 {mu}m (194 THz). The measurements were made using cavity-enhanced, diode-laser-based saturation spectroscopy. With one laser system stabilized to the P(16) line and a second laser system stabilized to the line whose frequency was to be determined, a Cr:YAG frequency comb was employed to accurately measure the tetrahertz level frequency intervals. The results are compared with recent work from other groups and indicate that these lines would form a basis for a high-quality atlas of reference frequencies for this region of the spectrum.

  4. Comment on ``Photonic bands in two-dimensional microplasma array. I. Theoretical derivation of band structures of electromagnetic waves'' [J. Appl. Phys. 101, 073304 (2007)

    NASA Astrophysics Data System (ADS)

    Zhang, Hai-feng; Liu, Shao-bin; Kong, Xiang-kun; Zhou, Liang; Li, Chun-zao; Bian, Bo-rui

    2011-07-01

    Recently, theoretical derivation of band structures of electromagnetic waves in two-dimensional microplasma array has been induced by Osamu Sakai et al. [J. Appl. Phys. 101, 073304 (2007)] using a modified plane wave expansion (PWE) method and a frequency-dependent finite difference time-domain (FDTD) method. This report reveals band diagrams with the effects of plasma electron collision frequency, especially focuses on the TE wave by nonmagnetized plasma. Although the band diagrams of TE wave and formulas of calculation look correct at first glance, there are some mistakes in the report which are unfortunately ignored by the authors. The correct formulas of the modified PWE method and FDTD method will be proposed.

  5. Telecommunication Wavelength-Band Single-Photon Emission from Single Large InAs Quantum Dots Nucleated on Low-Density Seed Quantum Dots

    NASA Astrophysics Data System (ADS)

    Chen, Ze-Sheng; Ma, Ben; Shang, Xiang-Jun; He, Yu; Zhang, Li-Chun; Ni, Hai-Qiao; Wang, Jin-Liang; Niu, Zhi-Chuan

    2016-08-01

    Single-photon emission in the telecommunication wavelength band is realized with self-assembled strain-coupled bilayer InAs quantum dots (QDs) embedded in a planar microcavity on GaAs substrate. Low-density large QDs in the upper layer active for ~1.3 μm emission are fabricated by precisely controlling the indium deposition amount and applying a gradient indium flux in both QD layers. Time-resolved photoluminescence (PL) intensity suggested that the radiative lifetime of their exciton emission is 1.5~1.6 ns. The second-order correlation function of g 2(0) < 0.5 which demonstrates a pure single-photon emission.

  6. Telecommunication Wavelength-Band Single-Photon Emission from Single Large InAs Quantum Dots Nucleated on Low-Density Seed Quantum Dots.

    PubMed

    Chen, Ze-Sheng; Ma, Ben; Shang, Xiang-Jun; He, Yu; Zhang, Li-Chun; Ni, Hai-Qiao; Wang, Jin-Liang; Niu, Zhi-Chuan

    2016-12-01

    Single-photon emission in the telecommunication wavelength band is realized with self-assembled strain-coupled bilayer InAs quantum dots (QDs) embedded in a planar microcavity on GaAs substrate. Low-density large QDs in the upper layer active for ~1.3 μm emission are fabricated by precisely controlling the indium deposition amount and applying a gradient indium flux in both QD layers. Time-resolved photoluminescence (PL) intensity suggested that the radiative lifetime of their exciton emission is 1.5~1.6 ns. The second-order correlation function of g (2)(0) < 0.5 which demonstrates a pure single-photon emission.

  7. Telecommunication Wavelength-Band Single-Photon Emission from Single Large InAs Quantum Dots Nucleated on Low-Density Seed Quantum Dots.

    PubMed

    Chen, Ze-Sheng; Ma, Ben; Shang, Xiang-Jun; He, Yu; Zhang, Li-Chun; Ni, Hai-Qiao; Wang, Jin-Liang; Niu, Zhi-Chuan

    2016-12-01

    Single-photon emission in the telecommunication wavelength band is realized with self-assembled strain-coupled bilayer InAs quantum dots (QDs) embedded in a planar microcavity on GaAs substrate. Low-density large QDs in the upper layer active for ~1.3 μm emission are fabricated by precisely controlling the indium deposition amount and applying a gradient indium flux in both QD layers. Time-resolved photoluminescence (PL) intensity suggested that the radiative lifetime of their exciton emission is 1.5~1.6 ns. The second-order correlation function of g (2)(0) < 0.5 which demonstrates a pure single-photon emission. PMID:27576522

  8. Direct Observation of Two-Step Photon Absorption in an InAs/GaAs Single Quantum Dot for the Operation of Intermediate-Band Solar Cells.

    PubMed

    Nozawa, Tomohiro; Takagi, Hiroyuki; Watanabe, Katsuyuki; Arakawa, Yasuhiko

    2015-07-01

    We present the first direct observation of two-step photon absorption in an InAs/GaAs single quantum dot (QD) using photocurrent spectroscopy with two lasers. The sharp peaks of the photocurrent are shifted due to the quantum confined Stark effect, indicating that the photocurrent from a single QD is obtained. In addition, the intensity of the peaks depends on the power of the secondary laser. These results reveal the direct demonstration of the two-step photon absorption in a single QD. This is an essential result for both the fundamental operation and the realization of ultrahigh solar-electricity energy conversion in quantum dot intermediate-band solar cells.

  9. Theoretical analysis of a palladium-based one-dimensional metallo-dielectric photonic band gap structure for applications to H2 sensors

    NASA Astrophysics Data System (ADS)

    Vincenti, Maria Antonietta; Trevisi, Simona; De Sario, Marco; Petruzzelli, Vincenzo; D'Orazio, Antonella; Prudenzano, Francesco; Cioffi, Nicola; de Ceglia, Domenico; Scalora, Michael

    2008-03-01

    In this paper we report a numerical study of a palladium-based metallo-dielectric photonic band gap structure for the purpose of detecting H2. In particular, and as an example, we will explore applications to the diagnosis of lactose malabsorption, more commonly known as lactose intolerance condition. This pathology occurs as a result of an incomplete absorption or digestion of different substances, causing an increased spontaneous emission of H2 in human breath. Palladium is considered in order to exploit its well known ability to absorb hydrogen spontaneously. The proposed structure is particularly able to detect the lactose malabsorption level of the patient with relatively high sensitivity and rapidity.

  10. Simple Experimental Verification of the Relation between the Band-Gap Energy and the Energy of Photons Emitted by LEDs

    ERIC Educational Resources Information Center

    Precker, Jurgen W.

    2007-01-01

    The wavelength of the light emitted by a light-emitting diode (LED) is intimately related to the band-gap energy of the semiconductor from which the LED is made. We experimentally estimate the band-gap energies of several types of LEDs, and compare them with the energies of the emitted light, which ranges from infrared to white. In spite of…

  11. Band alignment and photon extraction studies of Na-doped MgZnO/Ga-doped ZnO heterojunction for light-emitter applications

    SciTech Connect

    Pandey, Sushil Kumar; Awasthi, Vishnu; Sengar, Brajendra Singh; Garg, Vivek; Sharma, Pankaj; Mukherjee, Shaibal; Kumar, Shailendra; Mukherjee, C.

    2015-10-28

    Ultraviolet photoelectron spectroscopy is carried out to measure the energy discontinuity at the interface of p-type Na-doped MgZnO (NMZO)/n-type Ga-doped ZnO (GZO) heterojunction grown by dual ion beam sputtering. The offset values at valence band and conduction band of NMZO/GZO heterojunction are calculated to be 1.93 and −2.36 eV, respectively. The p-type conduction in NMZO film has been confirmed by Hall measurement and band structure. Moreover, the effect of Ar{sup +} ion sputtering on the valence band onset values of NMZO and GZO thin films has been investigated. This asymmetric waveguide structure formed by the lower refractive index of GZO than that of NMZO indicates that easy extraction of photons generated in GZO through the NMZO layer into free space. The asymmetric waveguide structure has potential applications to produce ZnO-based light emitters with high extraction efficiency.

  12. Temperature dependence of band gap ratio and Q-factor defect mode in a semiconductor quaternary alloy hexagonal photonic-crystal hole slab

    NASA Astrophysics Data System (ADS)

    Sánchez-Cano, R.; Porras-Montenegro, N.

    2016-04-01

    We present numerical predictions for the photonic TE-like band gap ratio and the quality factors of symmetric localized defect as a function of the thickness slab and temperature by the use of plane wave expansion and the finite-difference time-domain methods. The photonic-crystal hole slab is composed of a 2D hexagonal array with identical air holes and a circular cross section, embedded in a non-dispersive III-V semiconductor quaternary alloy slab, which has a high value of dielectric function in the near-infrared region, and the symmetric defect is formed by increasing the radius of a single hole in the 2D hexagonal lattice. We show that the band gap ratio depends linearly on the temperature in the range 150-400 K. Our results show a strong temperature dependence of the quality factor Q, the maximum (Q = 7000) is reached at T = 350 hbox {K}, but if the temperature continues to increase, the efficiency drops sharply. Furthermore, we present numerical predictions for the electromagnetic field distribution at T = 350 hbox {K}.

  13. Monolithically integrated absolute frequency comb laser system

    DOEpatents

    Wanke, Michael C.

    2016-07-12

    Rather than down-convert optical frequencies, a QCL laser system directly generates a THz frequency comb in a compact monolithically integrated chip that can be locked to an absolute frequency without the need of a frequency-comb synthesizer. The monolithic, absolute frequency comb can provide a THz frequency reference and tool for high-resolution broad band spectroscopy.

  14. Optimal focusing for maximal collection of entangled narrow-band photon pairs into single-mode fibers

    SciTech Connect

    Ljunggren, Daniel; Tengner, Maria

    2005-12-15

    We present a theoretical and experimental investigation of the emission characteristics and the flux of photon pairs generated by spontaneous parametric downconversion in quasi-phase matched bulk crystals for the use in quantum communication sources. We show that, by careful design, one can attain well defined modes close to the fundamental mode of optical fibers and obtain high coupling efficiencies also for bulk crystals, these being more easily aligned than crystal waveguides. We distinguish between singles coupling, {gamma}{sub s} and {gamma}{sub i}, conditional coincidence, {mu}{sub i|s}, and pair coupling, {gamma}{sub c}, and show how each of these parameters can be maximized by varying the focusing of the pump mode and the fiber-matched modes using standard optical elements. Specifically we analyze a periodically poled KTP-crystal pumped by a 532 nm laser creating photon pairs at 810 nm and 1550 nm. Numerical calculations lead to coupling efficiencies above 93% at optimal focusing, which is found by the geometrical relation L/z{sub R} to be {approx_equal}1 to 2 for the pump mode and {approx_equal}2 to 3 for the fiber-modes, where L is the crystal length and z{sub R} is the Rayleigh-range of the mode-profile. These results are independent on L. By showing that the single-mode bandwidth decreases {proportional_to}1/L, we can therefore design the source to produce and couple narrow bandwidth photon pairs well into the fibers. Smaller bandwidth means both less chromatic dispersion for long propagation distances in fibers, and that telecom Bragg gratings can be utilized to compensate for broadened photon packets--a vital problem for time-multiplexed qubits. Longer crystals also yield an increase in fiber photon flux {proportional_to}{radical}(L), and so, assuming correct focusing, we can only see advantages using long crystals.

  15. High resolution spectroscopy of silane with an external-cavity quantum cascade laser: Absolute line strengths of the ν3 fundamental band at 4.6 μm

    NASA Astrophysics Data System (ADS)

    van Helden, J. H.; Lopatik, D.; Nave, A.; Lang, N.; Davies, P. B.; Röpcke, J.

    2015-01-01

    The introduction of room temperature continuous wave external-cavity quantum cascade lasers (EC-QCLs) with narrow linewidths has greatly facilitated high resolution spectroscopy over wide spectral ranges in the mid-infrared (MIR) region. Using the wide tuning range of an EC-QCL we have measured the absolute line strengths of many P-branch transitions of the stretching dyad of the ν3 fundamental band of 28SiH4 between 2096 and 2178 cm-1. Furthermore, the high spectral resolution available has enabled us to resolve and measure representative examples of the tetrahedral splittings associated with each component of the P-branch. The positions of these components are in excellent agreement with spherical top data system (STDS) predictions and theoretical transitions from the TDS spectroscopic database for spherical top molecules. These are the first measurements of these line strengths of 28SiH4 and are an example of the applicability of high-powered, widely tunable EC-QCLs to high resolution spectroscopy.

  16. Design and demonstration of ultra-fast W-band photonic transmitter-mixer and detectors for 25 Gbits/sec error-free wireless linking.

    PubMed

    Chen, Nan-Wei; Shi, Jin-Wei; Tsai, Hsuan-Ju; Wun, Jhih-Min; Kuo, Fong-Ming; Hesler, Jeffery; Crowe, Thomas W; Bowers, John E

    2012-09-10

    A 25 Gbits/s error-free on-off-keying (OOK) wireless link between an ultra high-speed W-band photonic transmitter-mixer (PTM) and a fast W-band envelope detector is demonstrated. At the transmission end, the high-speed PTM is developed with an active near-ballistic uni-traveling carrier photodiode (NBUTC-PD) integrated with broadband front-end circuitry via the flip-chip bonding technique. Compared to our previous work, the wireless data rate is significantly increased through the improvement on the bandwidth of the front-end circuitry together with the reduction of the intermediate-frequency (IF) driving voltage of the active NBUTC-PD. The demonstrated PTM has a record-wide IF modulation (DC-25 GHz) and optical-to-electrical fractional bandwidths (68-128 GHz, ~67%). At the receiver end, the demodulation is realized with an ultra-fast W-band envelope detector built with a zero-bias Schottky barrier diode with a record wide video bandwidth (37 GHz) and excellent sensitivity. The demonstrated PTM is expected to find applications in multi-gigabit short-range wireless communication.

  17. Teaching Absolute Value Meaningfully

    ERIC Educational Resources Information Center

    Wade, Angela

    2012-01-01

    What is the meaning of absolute value? And why do teachers teach students how to solve absolute value equations? Absolute value is a concept introduced in first-year algebra and then reinforced in later courses. Various authors have suggested instructional methods for teaching absolute value to high school students (Wei 2005; Stallings-Roberts…

  18. Optical parametric chirped pulse amplification and spectral shaping of a continuum generated in a photonic band gap fiber.

    PubMed

    Hugonnot, E; Somekh, M; Villate, D; Salin, F; Freysz, E

    2004-05-31

    A chirped pulse, spectrally broadened in a photonic bandgap optical fiber by 120 fs Ti:Sapphire laser pulses, is parametrically amplified in a BBO crystal pumped by a frequency doubled nanosecond Nd:YAG laser pulse. Without changing the frequency of the Ti:Sapphire, a spectral tunability of the amplified pulses is demonstrated. The possibility to achieve broader spectral range amplification is confirmed for a non-collinear pump-signal interaction geometry. For optimal non-collinear interaction geometry, the pulse duration of the original and amplified pulse are similar. Finally, we demonstrate that the combination of two BBO crystals makes it possible to spectrally shape the amplified pulses.

  19. Widely tunable monolithic dual-mode laser for W-band photonic millimeter-wave generation and all-optical clock recovery.

    PubMed

    Pan, Biwei; Guo, Lu; Zhang, Limeng; Lu, Dna; Huo, Li; Lou, Caiyun; Zhao, Lingjuan

    2016-04-10

    We demonstrate a monolithic dual-mode amplified feedback laser for photonic millimeter-wave generation and all-optical clock recovery. Dual-mode lasing with beating frequency around 100 GHz was realized by using a single-mode distributed feedback (DFB) laser with a short feedback cavity that was integrated by simple quantum-well intermixing technology. By tuning the bias currents of the laser sections, the beating-frequency can be continuously tuned from 75 to 109 GHz, almost covering the entire W-band (75-110 GHz). Furthermore, by using this device, an all-optical clock recovery for 100 Gbit/s return-to-zero on-off-keying signal was achieved with a timing jitter of 301 fs.

  20. Cryogenic testing of the 2.1 GHz five-cell superconducting RF cavity with a photonic band gap coupler cell

    NASA Astrophysics Data System (ADS)

    Arsenyev, Sergey A.; Temkin, Richard J.; Haynes, W. Brian; Shchegolkov, Dmitry Yu.; Simakov, Evgenya I.; Tajima, Tsuyoshi; Boulware, Chase H.; Grimm, Terrence L.; Rogacki, Adam R.

    2016-05-01

    We present results from cryogenic tests of the multi-cell superconducting radio frequency (SRF) cavity with a photonic band gap (PBG) coupler cell. Achieving high average beam currents is particularly desirable for future light sources and particle colliders based on SRF energy-recovery-linacs (ERLs). Beam current in ERLs is limited by the beam break-up instability, caused by parasitic higher order modes (HOMs) interacting with the beam in accelerating cavities. A PBG cell incorporated in an accelerating cavity can reduce the negative effect of HOMs by providing a frequency selective damping mechanism, thus allowing significantly higher beam currents. The multi-cell cavity was designed and fabricated of niobium. Two cryogenic (vertical) tests were conducted. The high unloaded Q-factor was demonstrated at a temperature of 4.2 K at accelerating gradients up to 3 MV/m. The measured value of the unloaded Q-factor was 1.55 × 108, in agreement with prediction.

  1. Photonic frequency-quadrupling and balanced pre-coding technologies for W-band QPSK vector mm-wave signal generation based on a single DML

    NASA Astrophysics Data System (ADS)

    Wang, Yanyi; Yang, Chao; Chi, Nan; Yu, Jianjun

    2016-05-01

    We propose a novel scheme for high-frequency quadrature phase shift keying (QPSK) photonic vector signal generation based on a single directly modulated laser (DML) employing photonic frequency quadrupling and balanced pre-coding technologies. In order to realize frequency quadrupling, a wavelength selective switch (WSS) is intruded in our experiment. The intruded WSS combined with DML can not only realize high-frequency vector signal generation but also simplify the architecture. We experimentally demonstrate 1-or 2-Gbaud QPSK vector signal generation at 88 GHz based on our proposed scheme. The generated 1-Gbaud balanced pre-coded QPSK vector signal is transmitted 0.5-m wireless distance with the bit-error-ratio (BER) below hard-decision forward-error-correction (HD-FEC) threshold of 3.8×10-3. To our knowledge, this is the first time to demonstrate W-band mm-wave vector signal based on a single DML with quadrupling frequency and pre-coding technologies.

  2. Competitive behavior of photons contributing to junction voltage jump in narrow band-gap semiconductor multi-quantum-well laser diodes at lasing threshold

    NASA Astrophysics Data System (ADS)

    Feng, Liefeng; Yang, Xiufang; Li, Yang; Li, Ding; Wang, Cunda; Yao, Dongsheng; Hu, Xiaodong; Li, Hongru

    2015-04-01

    The junction behavior of different narrow band-gap multi-quantum-well (MQW) laser diodes (LDs) confirmed that the jump in the junction voltage in the threshold region is a general characteristic of narrow band-gap LDs. The relative change in the 1310 nm LD is the most obvious. To analyze this sudden voltage change, the threshold region is divided into three stages by Ithl and Ithu, as shown in Fig. 2; Ithl is the conventional threshold, and as long as the current is higher than this threshold, lasing exists and the IdV/dI-I plot drops suddenly; Ithu is the steady lasing point, at which the separation of the quasi-Fermi levels of electron and holes across the active region (Vj) is suddenly pinned. Based on the evolutionary model of dissipative structure theory, the rate equations of the photons in a single-mode LD were deduced in detail at Ithl and Ithu. The results proved that the observed behavior of stimulated emission suddenly substituting for spontaneous emission, in a manner similar to biological evolution, must lead to a sudden increase in the injection carriers in the threshold region, which then causes the sudden increase in the junction voltage in this region.

  3. Surface passivation of a photonic crystal band-edge laser by atomic layer deposition of SiO2 and its application for biosensing

    NASA Astrophysics Data System (ADS)

    Cha, Hyungrae; Lee, Jeongkug; Jordan, Luke R.; Lee, Si Hoon; Oh, Sang-Hyun; Kim, Hyo Jin; Park, Juhun; Hong, Seunghun; Jeon, Heonsu

    2015-02-01

    We report on the conformal surface passivation of photonic crystal (PC) laser devices with an ultrathin dielectric layer. Air-bridge-type Γ-point band-edge lasers (BELs) are fabricated by forming a honeycomb lattice two-dimensional PC structure into an InGaAsP multiple-quantum-well epilayer. Atomic layer deposition (ALD) is employed for conformal deposition of a few-nanometer-thick SiO2 layer over the entire device surface, not only on the top and bottom surfaces of the air-bridge membrane but also on the air-hole sidewalls. Despite its extreme thinness, the ALD passivation layer is found to protect the InGaAsP BEL devices from harsh chemicals. In addition, the ALD-SiO2 is compatible with the silane-based surface chemistry, which allows us to use ALD-passivated BEL devices as label-free biosensors. The standard streptavidin-biotin interaction shifts the BEL lasing wavelength by ~1 nm for the dipole-like Γ-point band-edge mode. A sharp lasing line (<0.2 nm, full width at half-maximum) and a large refractive index sensitivity (~163 nm per RIU) produce a figure of merit as high as ~800 for our BEL biosensor, which is at least an order of magnitude higher than those of more common biosensors that rely on a broad resonance peak, showing that our nanolaser structures are suitable for highly sensitive biosensor applications.

  4. Competitive behavior of photons contributing to junction voltage jump in narrow band-gap semiconductor multi-quantum-well laser diodes at lasing threshold

    SciTech Connect

    Feng, Liefeng E-mail: lihongru@nankai.edu.cn; Yang, Xiufang; Wang, Cunda; Yao, Dongsheng; Li, Yang; Li, Ding; Hu, Xiaodong; Li, Hongru E-mail: lihongru@nankai.edu.cn

    2015-04-15

    The junction behavior of different narrow band-gap multi-quantum-well (MQW) laser diodes (LDs) confirmed that the jump in the junction voltage in the threshold region is a general characteristic of narrow band-gap LDs. The relative change in the 1310 nm LD is the most obvious. To analyze this sudden voltage change, the threshold region is divided into three stages by I{sub th}{sup l} and I{sub th}{sup u}, as shown in Fig. 2; I{sub th}{sup l} is the conventional threshold, and as long as the current is higher than this threshold, lasing exists and the IdV/dI-I plot drops suddenly; I{sub th}{sup u} is the steady lasing point, at which the separation of the quasi-Fermi levels of electron and holes across the active region (V{sub j}) is suddenly pinned. Based on the evolutionary model of dissipative structure theory, the rate equations of the photons in a single-mode LD were deduced in detail at I{sub th}{sup l} and I{sub th}{sup u}. The results proved that the observed behavior of stimulated emission suddenly substituting for spontaneous emission, in a manner similar to biological evolution, must lead to a sudden increase in the injection carriers in the threshold region, which then causes the sudden increase in the junction voltage in this region.

  5. Surface passivation of a photonic crystal band-edge laser by atomic layer deposition of SiO2 and its application for biosensing.

    PubMed

    Cha, Hyungrae; Lee, Jeongkug; Jordan, Luke R; Lee, Si Hoon; Oh, Sang-Hyun; Kim, Hyo Jin; Park, Juhun; Hong, Seunghun; Jeon, Heonsu

    2015-02-28

    We report on the conformal surface passivation of photonic crystal (PC) laser devices with an ultrathin dielectric layer. Air-bridge-type Γ-point band-edge lasers (BELs) are fabricated by forming a honeycomb lattice two-dimensional PC structure into an InGaAsP multiple-quantum-well epilayer. Atomic layer deposition (ALD) is employed for conformal deposition of a few-nanometer-thick SiO2 layer over the entire device surface, not only on the top and bottom surfaces of the air-bridge membrane but also on the air-hole sidewalls. Despite its extreme thinness, the ALD passivation layer is found to protect the InGaAsP BEL devices from harsh chemicals. In addition, the ALD-SiO2 is compatible with the silane-based surface chemistry, which allows us to use ALD-passivated BEL devices as label-free biosensors. The standard streptavidin-biotin interaction shifts the BEL lasing wavelength by ∼1 nm for the dipole-like Γ-point band-edge mode. A sharp lasing line (<0.2 nm, full width at half-maximum) and a large refractive index sensitivity (∼163 nm per RIU) produce a figure of merit as high as ∼800 for our BEL biosensor, which is at least an order of magnitude higher than those of more common biosensors that rely on a broad resonance peak, showing that our nanolaser structures are suitable for highly sensitive biosensor applications.

  6. Eosinophil count - absolute

    MedlinePlus

    Eosinophils; Absolute eosinophil count ... the white blood cell count to give the absolute eosinophil count. ... than 500 cells per microliter (cells/mcL). Normal value ranges may vary slightly among different laboratories. Talk ...

  7. Single-sideband W-band photonic vector millimeter-wave signal generation by one single I/Q modulator.

    PubMed

    Li, Xinying; Xu, Yuming; Yu, Jianjun

    2016-09-15

    We propose a new scheme to generate single-sideband (SSB) photonic vector millimeter-wave (mm-wave) signal adopting asymmetrical SSB modulation enabled by a single in-phase/quadrature (I/Q) modulator. The driving signal for the I/Q modulator is generated by software-based digital signal processing (DSP) instead of a complicated transmitter electrical circuit, which significantly simplifies the system architecture and increases system stability. One vector-modulated optical sideband and one unmodulated optical sideband, with different sideband frequencies, located at two sides of a significantly suppressed central optical carrier, are generated by the I/Q modulator and used for heterodyne beating to generate the electrical vector mm-wave signal. The two optical sidebands are robust to fiber dispersion and can be transmitted over relatively long-haul fiber. We experimentally demonstrate the generation and transmission of 4-Gbaud 80-GHz quadrature-phase-shift-keying-modulated (QPSK-modulated) SSB vector mm-wave signal over 240-km single-mode fiber-28 without optical dispersion compensation.

  8. Single-sideband W-band photonic vector millimeter-wave signal generation by one single I/Q modulator.

    PubMed

    Li, Xinying; Xu, Yuming; Yu, Jianjun

    2016-09-15

    We propose a new scheme to generate single-sideband (SSB) photonic vector millimeter-wave (mm-wave) signal adopting asymmetrical SSB modulation enabled by a single in-phase/quadrature (I/Q) modulator. The driving signal for the I/Q modulator is generated by software-based digital signal processing (DSP) instead of a complicated transmitter electrical circuit, which significantly simplifies the system architecture and increases system stability. One vector-modulated optical sideband and one unmodulated optical sideband, with different sideband frequencies, located at two sides of a significantly suppressed central optical carrier, are generated by the I/Q modulator and used for heterodyne beating to generate the electrical vector mm-wave signal. The two optical sidebands are robust to fiber dispersion and can be transmitted over relatively long-haul fiber. We experimentally demonstrate the generation and transmission of 4-Gbaud 80-GHz quadrature-phase-shift-keying-modulated (QPSK-modulated) SSB vector mm-wave signal over 240-km single-mode fiber-28 without optical dispersion compensation. PMID:27628347

  9. Sub-GHz-resolution C-band Nyquist-filtering interleaver on a high-index-contrast photonic integrated circuit.

    PubMed

    Zhuang, Leimeng; Zhu, Chen; Corcoran, Bill; Burla, Maurizio; Roeloffzen, Chris G H; Leinse, Arne; Schröder, Jochen; Lowery, Arthur J

    2016-03-21

    Modern optical communications rely on high-resolution, high-bandwidth filtering to maximize the data-carrying capacity of fiber-optic networks. Such filtering typically requires high-speed, power-hungry digital processes in the electrical domain. Passive optical filters currently provide high bandwidths with low power consumption, but at the expense of resolution. Here, we present a passive filter chip that functions as an optical Nyquist-filtering interleaver featuring sub-GHz resolution and a near-rectangular passband with 8% roll-off. This performance is highly promising for high-spectral-efficiency Nyquist wavelength division multiplexed (N-WDM) optical super-channels. The chip provides a simple two-ring-resonator-assisted Mach-Zehnder interferometer, which has a sub-cm2 footprint owing to the high-index-contrast Si3N4/SiO2 waveguide, while manifests low wavelength-dependency enabling C-band (> 4 THz) coverage with more than 160 effective free spectral ranges of 25 GHz. This device is anticipated to be a critical building block for spectrally-efficient, chip-scale transceivers and ROADMs for N-WDM super-channels in next-generation optical communication networks.

  10. Sub-GHz-resolution C-band Nyquist-filtering interleaver on a high-index-contrast photonic integrated circuit.

    PubMed

    Zhuang, Leimeng; Zhu, Chen; Corcoran, Bill; Burla, Maurizio; Roeloffzen, Chris G H; Leinse, Arne; Schröder, Jochen; Lowery, Arthur J

    2016-03-21

    Modern optical communications rely on high-resolution, high-bandwidth filtering to maximize the data-carrying capacity of fiber-optic networks. Such filtering typically requires high-speed, power-hungry digital processes in the electrical domain. Passive optical filters currently provide high bandwidths with low power consumption, but at the expense of resolution. Here, we present a passive filter chip that functions as an optical Nyquist-filtering interleaver featuring sub-GHz resolution and a near-rectangular passband with 8% roll-off. This performance is highly promising for high-spectral-efficiency Nyquist wavelength division multiplexed (N-WDM) optical super-channels. The chip provides a simple two-ring-resonator-assisted Mach-Zehnder interferometer, which has a sub-cm2 footprint owing to the high-index-contrast Si3N4/SiO2 waveguide, while manifests low wavelength-dependency enabling C-band (> 4 THz) coverage with more than 160 effective free spectral ranges of 25 GHz. This device is anticipated to be a critical building block for spectrally-efficient, chip-scale transceivers and ROADMs for N-WDM super-channels in next-generation optical communication networks. PMID:27136769

  11. Photonic crystal light source

    DOEpatents

    Fleming, James G.; Lin, Shawn-Yu; Bur, James A.

    2004-07-27

    A light source is provided by a photonic crystal having an enhanced photonic density-of-states over a band of frequencies and wherein at least one of the dielectric materials of the photonic crystal has a complex dielectric constant, thereby producing enhanced light emission at the band of frequencies when the photonic crystal is heated. The dielectric material can be a metal, such as tungsten. The spectral properties of the light source can be easily tuned by modification of the photonic crystal structure and materials. The photonic crystal light source can be heated electrically or other heating means. The light source can further include additional photonic crystals that exhibit enhanced light emission at a different band of frequencies to provide for color mixing. The photonic crystal light source may have applications in optical telecommunications, information displays, energy conversion, sensors, and other optical applications.

  12. Investigation on the magneto-optical Voigt effects in surface plasmon modes and anisotropic photonic band gap in the three-dimensional magnetized plasma photonic crystals as the mixed polarized modes considered

    NASA Astrophysics Data System (ADS)

    Zhang, Hai-Feng; Liu, Shao-Bin; Ding, Guo-Wen

    2014-10-01

    In this paper, the magneto-optical Voigt effects in surface plasmon modes and anisotropic photonic band gaps (PBGs) of the three-dimensional (3D) magnetized plasma photonic crystals (MPPCs) with face-centered-cubic lattices are theoretically investigated based on the modified plane wave expansion (PWE) method, which are the homogeneous Te (tellurium) spheres immersed in the homogeneous magnetized plasma background, as the mixed polarized modes are considered. The more general condition is considered, and the anisotropic PBGs are not only for the extraordinary and ordinary modes but also for mixed polarized modes. The equations for computing such anisotropic PBGs are theoretically deduced. Theoretical simulations show that the anisotropic PBGs and a flatbands region can be observed in the dispersive curve. Compared to the similar 3D MPPCs containing the isotropic dielectric or uniaxial material spheres, the larger PBGs can be obtained as the extraordinary axis of the inserted uniaxial material is along the Г-H symmetry line although the region of flatbands is also different. However, the relative bandwidths of PBGs for such two cases are almost the same. The interesting properties of surface plasmon modes can also be found, which are that the upper edge of flatbands region cannot be tuned by the filling factor but can almost linearly increase on increasing the plasma frequency and plasma cyclotron frequency (the external magnetic field), respectively. The effects of the filling factor, plasma frequency and plasma cyclotron frequency on the anisotropic PBGs are investigated in detail, respectively. Theoretical calculations also show that such PBGs can be manipulated by the parameters as mentioned above.

  13. Surface passivation of a photonic crystal band-edge laser by atomic layer deposition of SiO2 and its application for biosensing.

    PubMed

    Cha, Hyungrae; Lee, Jeongkug; Jordan, Luke R; Lee, Si Hoon; Oh, Sang-Hyun; Kim, Hyo Jin; Park, Juhun; Hong, Seunghun; Jeon, Heonsu

    2015-02-28

    We report on the conformal surface passivation of photonic crystal (PC) laser devices with an ultrathin dielectric layer. Air-bridge-type Γ-point band-edge lasers (BELs) are fabricated by forming a honeycomb lattice two-dimensional PC structure into an InGaAsP multiple-quantum-well epilayer. Atomic layer deposition (ALD) is employed for conformal deposition of a few-nanometer-thick SiO2 layer over the entire device surface, not only on the top and bottom surfaces of the air-bridge membrane but also on the air-hole sidewalls. Despite its extreme thinness, the ALD passivation layer is found to protect the InGaAsP BEL devices from harsh chemicals. In addition, the ALD-SiO2 is compatible with the silane-based surface chemistry, which allows us to use ALD-passivated BEL devices as label-free biosensors. The standard streptavidin-biotin interaction shifts the BEL lasing wavelength by ∼1 nm for the dipole-like Γ-point band-edge mode. A sharp lasing line (<0.2 nm, full width at half-maximum) and a large refractive index sensitivity (∼163 nm per RIU) produce a figure of merit as high as ∼800 for our BEL biosensor, which is at least an order of magnitude higher than those of more common biosensors that rely on a broad resonance peak, showing that our nanolaser structures are suitable for highly sensitive biosensor applications. PMID:25631610

  14. Design of single-polarization coupler based on dual-core photonic band-gap fiber implied in resonant fiber optic gyro

    NASA Astrophysics Data System (ADS)

    Xu, Zhenlong; Li, Xuyou; Zhang, Chunmei; Ling, Weiwei; Liu, Pan; Xia, Linlin; Yang, Hanrui

    2016-12-01

    A novel (to our knowledge) type of single-polarization (SP) coupler based on a dual-core photonic band-gap fiber (PBF) is proposed. The effects of structure parameters on the performance of this coupler are studied numerically based on the full vector finite element method (FEM). Finally, an optimal design with a length of 0.377 mm at the wavelength of 1.55 μm is achieved, and its implication in PBF-based fiber ring resonator (FRR), the effect of angular misalignment on the SP coupler are analyzed as well. When the SP coupler is incorporated into a PBF-based FRR, it functions as the power splitter and the polarizer simultaneously, and can extinct the secondary eigenstate of polarization (ESOP) propagating in the FRR. The mode field of SP coupler can match with the polarization-maintaining (PM) PBF with ultra-low temperature sensitivity proposed in previous study, and an all PM-PBF based FRR can be established, which is of great significance in suppressing the temperature-related polarization fluctuation and improving the long-term stability for RFOG, and the SP coupler has high angular misalignment tolerance as well.

  15. Absolute nuclear material assay

    DOEpatents

    Prasad, Manoj K.; Snyderman, Neal J.; Rowland, Mark S.

    2012-05-15

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  16. Absolute nuclear material assay

    DOEpatents

    Prasad, Manoj K.; Snyderman, Neal J.; Rowland, Mark S.

    2010-07-13

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  17. Function photonic crystals

    NASA Astrophysics Data System (ADS)

    Wu, Xiang-Yao; Zhang, Bai-Jun; Yang, Jing-Hai; Liu, Xiao-Jing; Ba, Nuo; Wu, Yi-Heng; Wang, Qing-Cai

    2011-07-01

    In this paper, we present a new kind of function photonic crystals (PCs), whose refractive index is a function of space position. Conventional PCs structure grows from two materials, A and B, with different dielectric constants εA and εB. Based on Fermat principle, we give the motion equations of light in one-dimensional, two-dimensional and three-dimensional function photonic crystals. For one-dimensional function photonic crystals, we give the dispersion relation, band gap structure and transmissivity, and compare them with conventional photonic crystals, and we find the following: (1) For the vertical and non-vertical incidence light of function photonic crystals, there are band gap structures, and for only the vertical incidence light, the conventional PCs have band gap structures. (2) By choosing various refractive index distribution functions n( z), we can obtain more wider or more narrower band gap structure than conventional photonic crystals.

  18. Pseudo single crystal, direct-band-gap Ge{sub 0.89}Sn{sub 0.11} on amorphous dielectric layers towards monolithic 3D photonic integration

    SciTech Connect

    Li, Haofeng; Brouillet, Jeremy; Wang, Xiaoxin; Liu, Jifeng

    2014-11-17

    We demonstrate pseudo single crystal, direct-band-gap Ge{sub 0.89}Sn{sub 0.11} crystallized on amorphous layers at <450 °C towards 3D Si photonic integration. We developed two approaches to seed the lateral single crystal growth: (1) utilize the Gibbs-Thomson eutectic temperature depression at the tip of an amorphous GeSn nanotaper for selective nucleation; (2) laser-induced nucleation at one end of a GeSn strip. Either way, the crystallized Ge{sub 0.89}Sn{sub 0.11} is dominated by a single grain >18 μm long that forms optoelectronically benign twin boundaries with others grains. These pseudo single crystal, direct-band-gap Ge{sub 0.89}Sn{sub 0.11} patterns are suitable for monolithic 3D integration of active photonic devices on Si.

  19. Ion chambers simplify absolute intensity measurements in the vacuum ultraviolet

    NASA Technical Reports Server (NTRS)

    Sampson, J. A. R.

    1966-01-01

    Single or double ion chamber technique measures absolute radiation intensities in the extreme vacuum ultraviolet region of the spectrum. The ion chambers use rare gases as the ion carrier. Photon absorbed by the gas creates one ion pair so a measure of these is a measure of the number of incident photons.

  20. A Three-Dimensional Optical Photonic Crystal

    SciTech Connect

    Fleming, J.G.; Lin, S.

    1998-12-17

    The search for a photonic crystal to confine optical waves in all three dimensions (3D) has proven to be a formidable task. It evolves from an early theoretical suggestion [1,2], a brief skepticism [3-5] and triumph in developing the mm-wave [6-8] and infrared 3D photonic crystals [9]. Yet, the challenge remains, as the ultimate goal for optoelectronic applications is to realize a 3D crystal at X=1.5 pm communication wavelengths. Operating at visible and near infrared wavelengths, X=1-2 pm, a photonic crystal may enhance the spontaneous emission rate [1, 10] and give rise to a semiconductor lasers with a zero lasing threshold[11, 12]. Another important application is optically switching, routing and interconnecting light [13,14] with an ultrafast transmission speed of terabits per second. A photonic crystal may also serve as a platform for integrating an all-optical circuitry with multiple photonic components, such as waveguides and switches, built on one chip [15]. In this Letter, we report on the successful fabrication of a working 3D crystal operating at optical L The minimum feature size of the 3D structure is 180 nanometers. The 3D crystal is free from defects over the entire 6-inch silicon wafer and has an absolute photonic band gap centered at A.-1.6 pm. Our data provides the first conclusive evidence for the existence of a full 3D photonic band gap in optical A. This development will pave the way to tinier, cheaper, more effective waveguides, optical switches and lasers.

  1. The absolute yield, angular distribution and resonance widths of the 6.13, 6.92 and 7.12 MeV photons from the 340.5 keV resonance of the 19F(p,αγ) 16O reaction

    NASA Astrophysics Data System (ADS)

    Croft, S.

    1991-10-01

    Although the low lying resonances in the 19F(p,αγ) 16O reaction have been studied by many investigators in the past, only a few absolute determinations of the gamma-ray yield and branching ratios have been made. This is somewhat surprising in view of the widespread use of this reaction for the quantitative microanalysis of fluorine concentration profiles in the near surface regions of materials and for the calibration of gamma-ray detectors. In this work we report an absolute measurement of the yield, angular distribution and resonance widths of the 6.13, 6.92 and 7.12 MeV photons from the 340.5 keV resonance of the 19F(p,αγ) 16O reaction. Photons were produced by bombarding a semithick target of CaF 2 with protons from the Harwell 6 MV Van de Graaff accelerator. A 113 cm 3 HPGe spectrometer, with an energy resolution of 6.8 keV at 6129 keV, was used as the photon detector. This detector had previously been calibrated absolutely using a combination of radionuclide and thermal neutron capture gamma-ray sources at the neutron facility Badger, adjacent to the Harwell reactor DIDO. Measurements were made at seven angles in the range 0° - 150° permitting both differential and integral cross-sections to be derived. Geometrical correction factors were calculated using the Monte Carlo code EGS-4. A value for the reaction width was determined from the excitation curve. With conventional notation the principal results are as follows: γ1 : γ2 : γ3 = 0.9701:0.0033:0.0266; ΓCM = (2.08±0.13) keV; and Y( γ1) = (8.72±0.37)×10 4 6129 keV γμC -1as.

  2. Absolute Radiometric Calibration Of The Thematic Mapper

    NASA Astrophysics Data System (ADS)

    Slater, P. N.; Biggar, S. F.; Holm, R. G.; Jackson, R. D.; Mao, Y.; Moran, M. S.; Palmer, J. M.; Yuan, B.

    1986-11-01

    The results are presented of five in-flight absolute radiometric calibrations, made in the period July 1984 to November 1985, at White Sands, New Mexico, of the solar reflective bands of the Landsat-5 Thematic Mapper (TM) . The 23 bandcalibrations made on the five dates show a ± 2.8% RMS variation from the mean as a percentage of the mean.

  3. Absolute biological needs.

    PubMed

    McLeod, Stephen

    2014-07-01

    Absolute needs (as against instrumental needs) are independent of the ends, goals and purposes of personal agents. Against the view that the only needs are instrumental needs, David Wiggins and Garrett Thomson have defended absolute needs on the grounds that the verb 'need' has instrumental and absolute senses. While remaining neutral about it, this article does not adopt that approach. Instead, it suggests that there are absolute biological needs. The absolute nature of these needs is defended by appeal to: their objectivity (as against mind-dependence); the universality of the phenomenon of needing across the plant and animal kingdoms; the impossibility that biological needs depend wholly upon the exercise of the abilities characteristic of personal agency; the contention that the possession of biological needs is prior to the possession of the abilities characteristic of personal agency. Finally, three philosophical usages of 'normative' are distinguished. On two of these, to describe a phenomenon or claim as 'normative' is to describe it as value-dependent. A description of a phenomenon or claim as 'normative' in the third sense does not entail such value-dependency, though it leaves open the possibility that value depends upon the phenomenon or upon the truth of the claim. It is argued that while survival needs (or claims about them) may well be normative in this third sense, they are normative in neither of the first two. Thus, the idea of absolute need is not inherently normative in either of the first two senses. PMID:23586876

  4. Absolute biological needs.

    PubMed

    McLeod, Stephen

    2014-07-01

    Absolute needs (as against instrumental needs) are independent of the ends, goals and purposes of personal agents. Against the view that the only needs are instrumental needs, David Wiggins and Garrett Thomson have defended absolute needs on the grounds that the verb 'need' has instrumental and absolute senses. While remaining neutral about it, this article does not adopt that approach. Instead, it suggests that there are absolute biological needs. The absolute nature of these needs is defended by appeal to: their objectivity (as against mind-dependence); the universality of the phenomenon of needing across the plant and animal kingdoms; the impossibility that biological needs depend wholly upon the exercise of the abilities characteristic of personal agency; the contention that the possession of biological needs is prior to the possession of the abilities characteristic of personal agency. Finally, three philosophical usages of 'normative' are distinguished. On two of these, to describe a phenomenon or claim as 'normative' is to describe it as value-dependent. A description of a phenomenon or claim as 'normative' in the third sense does not entail such value-dependency, though it leaves open the possibility that value depends upon the phenomenon or upon the truth of the claim. It is argued that while survival needs (or claims about them) may well be normative in this third sense, they are normative in neither of the first two. Thus, the idea of absolute need is not inherently normative in either of the first two senses.

  5. Absolute radiometric calibration of the Thematic Mapper

    NASA Technical Reports Server (NTRS)

    Slater, P. N.; Biggar, S. F.; Holm, R. G.; Jackson, R. D.; Mao, Y.

    1986-01-01

    Calibration data for the solar reflective bands of the Landsat-5 TM obtained from five in-flight absolute radiometric calibrations from July 1984-November 1985 at White Sands, New Mexico are presented and analyzed. Ground reflectance and atmospheric data were utilized to predict the spectral radiance at the entrance pupil of the TM and the average number of digital counts in each TM band. The calibration of each of the TM solar reflective bands was calculated in terms of average digital counts/unit spectral radiance for each band. It is observed that for the 12 reflectance-based measurements the rms variation from the means as a percentage of the mean is + or - 1.9 percent; for the 11 measurements in the IR bands, it is + or - 3.4 percent; and the rms variation for all 23 measurements is + or - 2.8 percent.

  6. Microwave background constraints on mixing of photons with hidden photons

    SciTech Connect

    Mirizzi, Alessandro; Redondo, Javier; Sigl, Guenter E-mail: javier.redondo@desy.de

    2009-03-15

    Various extensions of the Standard Model predict the existence of hidden photons kinetically mixing with the ordinary photon. This mixing leads to oscillations between photons and hidden photons, analogous to the observed oscillations between different neutrino flavors. In this context, we derive new bounds on the photon-hidden photon mixing parameters using the high precision cosmic microwave background spectral data collected by the Far Infrared Absolute Spectrophotometer instrument on board of the Cosmic Background Explorer. Requiring the distortions of the CMB induced by the photon-hidden photon mixing to be smaller than experimental upper limits, this leads to a bound on the mixing angle {chi}{sub 0} {approx}< 10{sup -7}-10{sup -5} for hidden photon masses between 10{sup -14} eV and 10{sup -7} eV. This low-mass and low-mixing region of the hidden photon parameter space was previously unconstrained.

  7. The absolute path command

    2012-05-11

    The ap command traveres all symlinks in a given file, directory, or executable name to identify the final absolute path. It can print just the final path, each intermediate link along with the symlink chan, and the permissions and ownership of each directory component in the final path. It has functionality similar to "which", except that it shows the final path instead of the first path. It is also similar to "pwd", but it canmore » provide the absolute path to a relative directory from the current working directory.« less

  8. The absolute path command

    SciTech Connect

    Moody, A.

    2012-05-11

    The ap command traveres all symlinks in a given file, directory, or executable name to identify the final absolute path. It can print just the final path, each intermediate link along with the symlink chan, and the permissions and ownership of each directory component in the final path. It has functionality similar to "which", except that it shows the final path instead of the first path. It is also similar to "pwd", but it can provide the absolute path to a relative directory from the current working directory.

  9. Narrow-band single photon emission at room temperature based on a single nitrogen-vacancy center coupled to an all-fiber-cavity

    SciTech Connect

    Albrecht, Roland; Bommer, Alexander; Becher, Christoph; Pauly, Christoph; Mücklich, Frank; Schell, Andreas W.; Engel, Philip; Benson, Oliver; Schröder, Tim; Reichel, Jakob

    2014-08-18

    We report the realization of a device based on a single Nitrogen-Vacancy (NV) center in diamond coupled to a fiber-cavity for use as single photon source (SPS). The device consists of two concave mirrors each directly fabricated on the facets of two optical fibers and a preselected nanodiamond containing a single NV center deposited onto one of these mirrors. Both, cavity in- and out-put are directly fiber-coupled, and the emission wavelength is easily tunable by variation of the separation of the two mirrors with a piezo-electric crystal. By coupling to the cavity, we achieve an increase of the spectral photon rate density by two orders of magnitude compared to free-space emission of the NV center. With this work, we establish a simple all-fiber based SPS with promising prospects for the integration into photonic quantum networks.

  10. ABSOLUTE POLARIMETRY AT RHIC.

    SciTech Connect

    OKADA; BRAVAR, A.; BUNCE, G.; GILL, R.; HUANG, H.; MAKDISI, Y.; NASS, A.; WOOD, J.; ZELENSKI, Z.; ET AL.

    2007-09-10

    Precise and absolute beam polarization measurements are critical for the RHIC spin physics program. Because all experimental spin-dependent results are normalized by beam polarization, the normalization uncertainty contributes directly to final physics uncertainties. We aimed to perform the beam polarization measurement to an accuracy Of {Delta}P{sub beam}/P{sub beam} < 5%. The absolute polarimeter consists of Polarized Atomic Hydrogen Gas Jet Target and left-right pairs of silicon strip detectors and was installed in the RHIC-ring in 2004. This system features proton-proton elastic scattering in the Coulomb nuclear interference (CNI) region. Precise measurements of the analyzing power A{sub N} of this process has allowed us to achieve {Delta}P{sub beam}/P{sub beam} = 4.2% in 2005 for the first long spin-physics run. In this report, we describe the entire set up and performance of the system. The procedure of beam polarization measurement and analysis results from 2004-2005 are described. Physics topics of AN in the CNI region (four-momentum transfer squared 0.001 < -t < 0.032 (GeV/c){sup 2}) are also discussed. We point out the current issues and expected optimum accuracy in 2006 and the future.

  11. Microresonator and associated method for producing and controlling photonic signals with a photonic bandgap delay apparatus

    NASA Technical Reports Server (NTRS)

    Fork, Richard Lynn (Inventor); Jones, Darryl Keith (Inventor); Keys, Andrew Scott (Inventor)

    2000-01-01

    By applying a photonic signal to a microresonator that includes a photonic bandgap delay apparatus having a photonic band edge transmission resonance at the frequency of the photonic signal, the microresonator imparts a predetermined delay to the photonic signal. The photonic bandgap delay apparatus also preferably has a photonic band edge transmission resonance bandwidth which is at least as wide as the bandwidth of the photonic signal such that a uniform delay is imparted over the entire bandwidth of the photonic signal. The microresonator also includes a microresonator cavity, typically defined by a pair of switchable mirrors, within which the photonic bandgap delay apparatus is disposed. By requiring the photonic signal to oscillate within the microresonator cavity so as to pass through the photonic bandgap delay apparatus several times, the microresonator can controllably impart an adjustable delay to the photonic signal.

  12. Absolute Equilibrium Entropy

    NASA Technical Reports Server (NTRS)

    Shebalin, John V.

    1997-01-01

    The entropy associated with absolute equilibrium ensemble theories of ideal, homogeneous, fluid and magneto-fluid turbulence is discussed and the three-dimensional fluid case is examined in detail. A sigma-function is defined, whose minimum value with respect to global parameters is the entropy. A comparison is made between the use of global functions sigma and phase functions H (associated with the development of various H-theorems of ideal turbulence). It is shown that the two approaches are complimentary though conceptually different: H-theorems show that an isolated system tends to equilibrium while sigma-functions allow the demonstration that entropy never decreases when two previously isolated systems are combined. This provides a more complete picture of entropy in the statistical mechanics of ideal fluids.

  13. Asteroid absolute magnitudes and slope parameters

    NASA Technical Reports Server (NTRS)

    Tedesco, Edward F.

    1991-01-01

    A new listing of absolute magnitudes (H) and slope parameters (G) has been created and published in the Minor Planet Circulars; this same listing will appear in the 1992 Ephemerides of Minor Planets. Unlike previous listings, the values of the current list were derived from fits of data at the V band. All observations were reduced in the same fashion using, where appropriate, a single basis default value of 0.15 for the slope parameter. Distances and phase angles were computed for each observation. The data for 113 asteroids was of sufficiently high quality to permit derivation of their H and G. These improved absolute magnitudes and slope parameters will be used to deduce the most reliable bias-corrected asteroid size-frequency distribution yet made.

  14. Photon-photon collisions

    SciTech Connect

    Burke, D.L.

    1982-10-01

    Studies of photon-photon collisions are reviewed with particular emphasis on new results reported to this conference. These include results on light meson spectroscopy and deep inelastic e..gamma.. scattering. Considerable work has now been accumulated on resonance production by ..gamma gamma.. collisions. Preliminary high statistics studies of the photon structure function F/sub 2//sup ..gamma../(x,Q/sup 2/) are given and comments are made on the problems that remain to be solved.

  15. Photon-photon colliders

    SciTech Connect

    Sessler, A.M.

    1995-04-01

    Since the seminal work by Ginsburg, et at., the subject of giving the Next Linear Collider photon-photon capability, as well as electron-positron capability, has drawn much attention. A 1990 article by V.I. Teinov describes the situation at that time. In March 1994, the first workshop on this subject was held. This report briefly reviews the physics that can be achieved through the photon-photon channel and then focuses on the means of achieving such a collider. Also reviewed is the spectrum of backscattered Compton photons -- the best way of obtaining photons. We emphasize the spectrum actually obtained in a collider with both polarized electrons and photons (peaked at high energy and very different from a Compton spectrum). Luminosity is estimated for the presently considered colliders, and interaction and conversion-point geometries are described. Also specified are laser requirements (such as wavelength, peak power, and average power) and the lasers that might be employed. These include conventional and free-electron lasers. Finally, we describe the R&D necessary to make either of these approaches viable and explore the use of the SLC as a test bed for a photon-photon collider of very high energy.

  16. Tunable photonic Bloch oscillations in electrically modulated photonic crystals.

    PubMed

    Wang, Gang; Huang, Ji Ping; Yu, Kin Wah

    2008-10-01

    We exploit theoretically the occurrence and tunability of photonic Bloch oscillations (PBOs) in one-dimensional photonic crystals (PCs) containing nonlinear composites. Because of the enhanced third-order nonlinearity (Kerr-type nonlinearity) of composites, photons undergo oscillations inside tilted photonic bands, which are achieved by the application of graded external-pump electric fields on such PCs, varying along the direction perpendicular to the surface of layers. The tunability of PBOs (including amplitude and period) is readily achieved by changing the field gradient. With an appropriate graded pump ac or dc electric field, terahertz PBOs can appear and cover a terahertz band in an electromagnetic spectrum.

  17. Absolute neutrino mass measurements

    SciTech Connect

    Wolf, Joachim

    2011-10-06

    The neutrino mass plays an important role in particle physics, astrophysics and cosmology. In recent years the detection of neutrino flavour oscillations proved that neutrinos carry mass. However, oscillation experiments are only sensitive to the mass-squared difference of the mass eigenvalues. In contrast to cosmological observations and neutrino-less double beta decay (0v2{beta}) searches, single {beta}-decay experiments provide a direct, model-independent way to determine the absolute neutrino mass by measuring the energy spectrum of decay electrons at the endpoint region with high accuracy.Currently the best kinematic upper limits on the neutrino mass of 2.2eV have been set by two experiments in Mainz and Troitsk, using tritium as beta emitter. The next generation tritium {beta}-experiment KATRIN is currently under construction in Karlsruhe/Germany by an international collaboration. KATRIN intends to improve the sensitivity by one order of magnitude to 0.2eV. The investigation of a second isotope ({sup 137}Rh) is being pursued by the international MARE collaboration using micro-calorimeters to measure the beta spectrum. The technology needed to reach 0.2eV sensitivity is still in the R and D phase. This paper reviews the present status of neutrino-mass measurements with cosmological data, 0v2{beta} decay and single {beta}-decay.

  18. Photon-photon colliders

    SciTech Connect

    Sessler, Andrew M.

    1996-01-01

    Since the seminal work by Ginsburg, et al., the subject of giving the Next Linear Collider photon-photon capability, as well as electron-positron capability, has drawn much attention [1]. A 1990 article by V.I. Telnov describes the situation at that time [2]. In March 1994, the first workshop on this subject was held [3]. This report briefly reviews the physics that can be achieved through the photon-photon channel and then focuses on the means of achieving such a collider. Also reviewed is the spectrum of backscattered Compton photons—the best way of obtaining photons. We emphasize the spectrum actually obtained in a collider with both polarized electrons and photons (peaked at high energy and very different from a Compton spectrum). Luminosity is estimated for the presently considered colliders, and interaction and conversion-point geometries are described. Also specified are laser requirements (such as wavelength, peak power, and average power) and the lasers that might be employed. These include conventional and free-electron lasers. Finally, we describe the R&D necessary to make either of these approaches viable and explore the use of the SLC as a test bed for a photon-photon collider of very high energy.

  19. Photon-photon collisions

    SciTech Connect

    Brodsky, S.J.

    1988-07-01

    Highlights of the VIIIth International Workshop on Photon-Photon Collisions are reviewed. New experimental and theoretical results were reported in virtually every area of ..gamma gamma.. physics, particularly in exotic resonance production and tests of quantum chromodynamics where asymptotic freedom and factorization theorems provide predictions for both inclusive and exclusive ..gamma gamma.. reactions at high momentum transfer. 73 refs., 12 figs.

  20. In-flight absolute radiometric calibration of the thematic mapper

    NASA Technical Reports Server (NTRS)

    Castle, K. R.; Holm, R. G.; Kastner, C. J.; Palmer, J. M.; Slater, P. N.; Dinguirard, M.; Ezra, C. E.; Jackson, R. D.; Savage, R. K.

    1984-01-01

    In order to determine temporal changes of the absolute radiometric calibration of the entire TM system in flight spectroradiometric measurements of the ground and the atmosphere were made simultaneously with TM image collections over the White Sands, New Mexico area. By entering the measured values in an atmospheric radiative transfer program, the radiance levels in four of the spectral bands of the TM were determined, band 1:0.45 to 0.52 micrometers, band 2:0.53 to 0.61 micrometers band 3:0.62 to 0.70 micrometers and 4:0.78 to 0.91 micrometers. These levels were compared to the output digital counts from the detectors that sampled the radiometrically measured ground area, thus providing an absolute radiometric calibration of the entire TM system utilizing those detectors.

  1. In-flight absolute radiometric calibration of the Thematic Mapper

    NASA Technical Reports Server (NTRS)

    Castle, K. R.; Holm, R. G.; Kastner, C. J.; Palmer, J. M.; Slater, P. N.; Dinguirard, M.; Ezra, C. E.; Jackson, R. D.; Savage, R. K.

    1984-01-01

    In order to determine temporal changes of the absolute radiometric calibration of the entire TM system in flight spectroradiometric measurements of the ground and the atmosphere were made simultaneously with TM image collections over the White Sands, NM area. By entering the measured values in an atmospheric radiative transfer program, the radiance levels in four of the spectral bands of the TM were determined, band 1: 0.45 to 0.52 micrometers, band 2: 0.53 to 0.61 micrometers, band 3: 0.62 to 0.70 micrometers, and 4: 0.78 to 0.91 micrometers. These levels were compared to the output digital counts from the detectors that sampled the radiometrically measured ground area, thus providing an absolute radiometric calibration of the entire TM system utilizing those detectors. Previously announced in STAR as N84-15633

  2. Absolute Identification by Relative Judgment

    ERIC Educational Resources Information Center

    Stewart, Neil; Brown, Gordon D. A.; Chater, Nick

    2005-01-01

    In unidimensional absolute identification tasks, participants identify stimuli that vary along a single dimension. Performance is surprisingly poor compared with discrimination of the same stimuli. Existing models assume that identification is achieved using long-term representations of absolute magnitudes. The authors propose an alternative…

  3. Be Resolute about Absolute Value

    ERIC Educational Resources Information Center

    Kidd, Margaret L.

    2007-01-01

    This article explores how conceptualization of absolute value can start long before it is introduced. The manner in which absolute value is introduced to students in middle school has far-reaching consequences for their future mathematical understanding. It begins to lay the foundation for students' understanding of algebra, which can change…

  4. The Carina Project: Absolute and Relative Calibrations

    NASA Astrophysics Data System (ADS)

    Corsi, C. E.; Bono, G.; Walker, A. R.; Brocato, E.; Buonanno, R.; Caputo, F.; Castellani, M.; Castellani, V.; Dall'Ora, M.; Marconi, M.; Monelli, M.; Nonino, M.; Pulone, L.; Ripepi, V.; Smith, H. A.

    We discuss the reduction strategy adopted to perform the relative and the absolute calibration of the Wide Field Imager (WFI) available at the 2.2m ESO/MPI telescope and of the Mosaic Camera (MC) available at the 4m CTIO Blanco telescope. To properly constrain the occurrence of deceptive systematic errors in the relative calibration we observed with each chip the same set of stars. Current photometry seems to suggest that the WFI shows a positional effect when moving from the top to the bottom of individual chips. Preliminary results based on an independent data set collected with the MC suggest that this camera is only marginally affected by the same problem. To perform the absolute calibration we observed with each chip the same set of standard stars. The sample covers a wide color range and the accuracy both in the B and in the V-band appears to be of the order of a few hundredths of magnitude. Finally, we briefly outline the observing strategy to improve both relative and absolute calibrations of mosaic CCD cameras.

  5. Breakdown of Bose-Einstein Distribution in Photonic Crystals

    PubMed Central

    Lo, Ping-Yuan; Xiong, Heng-Na; Zhang, Wei-Min

    2015-01-01

    In the last two decades, considerable advances have been made in the investigation of nano-photonics in photonic crystals. Previous theoretical investigations of photon dynamics were carried out at zero temperature. Here, we investigate micro/nano cavity photonics in photonic crystals at finite temperature. Due to photonic-band-gap-induced localized long-lived photon dynamics, we discover that cavity photons in photonic crystals do not obey Bose-Einstein statistical distribution. Within the photonic band gap and in the vicinity of the band edge, cavity photons combine the long-lived non-Markovain dynamics with thermal fluctuations together to form photon states that memorize the initial cavity state information. As a result, Bose-Einstein distribution is completely broken down in these regimes, even if the thermal energy is larger or much larger than the cavity detuning energy. In this investigation, a crossover phenomenon from equilibrium to nonequilibrium steady states is also revealed. PMID:25822135

  6. Breakdown of Bose-Einstein distribution in photonic crystals.

    PubMed

    Lo, Ping-Yuan; Xiong, Heng-Na; Zhang, Wei-Min

    2015-01-01

    In the last two decades, considerable advances have been made in the investigation of nano-photonics in photonic crystals. Previous theoretical investigations of photon dynamics were carried out at zero temperature. Here, we investigate micro/nano cavity photonics in photonic crystals at finite temperature. Due to photonic-band-gap-induced localized long-lived photon dynamics, we discover that cavity photons in photonic crystals do not obey Bose-Einstein statistical distribution. Within the photonic band gap and in the vicinity of the band edge, cavity photons combine the long-lived non-Markovain dynamics with thermal fluctuations together to form photon states that memorize the initial cavity state information. As a result, Bose-Einstein distribution is completely broken down in these regimes, even if the thermal energy is larger or much larger than the cavity detuning energy. In this investigation, a crossover phenomenon from equilibrium to nonequilibrium steady states is also revealed.

  7. Sentinel-2/MSI absolute calibration: first results

    NASA Astrophysics Data System (ADS)

    Lonjou, V.; Lachérade, S.; Fougnie, B.; Gamet, P.; Marcq, S.; Raynaud, J.-L.; Tremas, T.

    2015-10-01

    Sentinel-2 is an optical imaging mission devoted to the operational monitoring of land and coastal areas. It is developed in partnership between the European Commission and the European Space Agency. The Sentinel-2 mission is based on a satellites constellation deployed in polar sun-synchronous orbit. It will offer a unique combination of global coverage with a wide field of view (290km), a high revisit (5 days with two satellites), a high resolution (10m, 20m and 60m) and multi-spectral imagery (13 spectral bands in visible and shortwave infra-red domains). CNES is involved in the instrument commissioning in collaboration with ESA. This paper reviews all the techniques that will be used to insure an absolute calibration of the 13 spectral bands better than 5% (target 3%), and will present the first results if available. First, the nominal calibration technique, based on an on-board sun diffuser, is detailed. Then, we show how vicarious calibration methods based on acquisitions over natural targets (oceans, deserts, and Antarctica during winter) will be used to check and improve the accuracy of the absolute calibration coefficients. Finally, the verification scheme, exploiting photometer in-situ measurements over Lacrau plain, is described. A synthesis, including spectral coherence, inter-methods agreement and temporal evolution, will conclude the paper.

  8. Evaluation of the Absolute Regional Temperature Potential

    NASA Technical Reports Server (NTRS)

    Shindell, D. T.

    2012-01-01

    The Absolute Regional Temperature Potential (ARTP) is one of the few climate metrics that provides estimates of impacts at a sub-global scale. The ARTP presented here gives the time-dependent temperature response in four latitude bands (90-28degS, 28degS-28degN, 28-60degN and 60-90degN) as a function of emissions based on the forcing in those bands caused by the emissions. It is based on a large set of simulations performed with a single atmosphere-ocean climate model to derive regional forcing/response relationships. Here I evaluate the robustness of those relationships using the forcing/response portion of the ARTP to estimate regional temperature responses to the historic aerosol forcing in three independent climate models. These ARTP results are in good accord with the actual responses in those models. Nearly all ARTP estimates fall within +/-20%of the actual responses, though there are some exceptions for 90-28degS and the Arctic, and in the latter the ARTP may vary with forcing agent. However, for the tropics and the Northern Hemisphere mid-latitudes in particular, the +/-20% range appears to be roughly consistent with the 95% confidence interval. Land areas within these two bands respond 39-45% and 9-39% more than the latitude band as a whole. The ARTP, presented here in a slightly revised form, thus appears to provide a relatively robust estimate for the responses of large-scale latitude bands and land areas within those bands to inhomogeneous radiative forcing and thus potentially to emissions as well. Hence this metric could allow rapid evaluation of the effects of emissions policies at a finer scale than global metrics without requiring use of a full climate model.

  9. Photonic crystal surface-emitting lasers

    SciTech Connect

    Chua, Song Liang; Lu, Ling; Soljacic, Marin

    2015-06-23

    A photonic-crystal surface-emitting laser (PCSEL) includes a gain medium electromagnetically coupled to a photonic crystal whose energy band structure exhibits a Dirac cone of linear dispersion at the center of the photonic crystal's Brillouin zone. This Dirac cone's vertex is called a Dirac point; because it is at the Brillouin zone center, it is called an accidental Dirac point. Tuning the photonic crystal's band structure (e.g., by changing the photonic crystal's dimensions or refractive index) to exhibit an accidental Dirac point increases the photonic crystal's mode spacing by orders of magnitudes and reduces or eliminates the photonic crystal's distributed in-plane feedback. Thus, the photonic crystal can act as a resonator that supports single-mode output from the PCSEL over a larger area than is possible with conventional PCSELs, which have quadratic band edge dispersion. Because output power generally scales with output area, this increase in output area results in higher possible output powers.

  10. The Absolute Radiometric Calibration of Space - Sensors.

    NASA Astrophysics Data System (ADS)

    Holm, Ronald Gene

    1987-09-01

    The need for absolute radiometric calibration of space-based sensors will continue to increase as new generations of space sensors are developed. A reflectance -based in-flight calibration procedure is used to determine the radiance reaching the entrance pupil of the sensor. This procedure uses ground-based measurements coupled with a radiative transfer code to characterize the effects the atmosphere has on the signal reaching the sensor. The computed radiance is compared to the digital count output of the sensor associated with the image of a test site. This provides an update to the preflight calibration of the system and a check on the on-board internal calibrator. This calibration procedure was used to perform a series of five calibrations of the Landsat-5 Thematic Mapper (TM). For the 12 measurements made in TM bands 1-3, the RMS variation from the mean as a percentage of the mean is (+OR-) 1.9%, and for measurements in the IR, TM bands 4,5, and 7, the value is (+OR-) 3.4%. The RMS variation for all 23 measurements is (+OR-) 2.8%. The absolute calibration techniques were put to another test with a series of three calibration of the SPOT-1 High Resolution Visible, (HRV), sensors. The ratio, HRV-2/HRV-1, of absolute calibration coefficients compared very well with ratios of histogrammed data obtained when the cameras simultaneously imaged the same ground site. Bands PA, B1 and B3 agreed to within 3%, while band B2 showed a 7% difference. The procedure for performing a satellite calibration was then used to demonstrate how a calibrated satellite sensor can be used to quantitatively evaluate surface reflectance over a wide range of surface features. Predicted reflectance factors were compared to values obtained from aircraft -based radiometer data. This procedure was applied on four dates with two different surface conditions per date. A strong correlation, R('2) = .996, was shown between reflectance values determined from satellite imagery and low-flying aircraft

  11. Spatial filtering with photonic crystals

    SciTech Connect

    Maigyte, Lina; Staliunas, Kestutis

    2015-03-15

    Photonic crystals are well known for their celebrated photonic band-gaps—the forbidden frequency ranges, for which the light waves cannot propagate through the structure. The frequency (or chromatic) band-gaps of photonic crystals can be utilized for frequency filtering. In analogy to the chromatic band-gaps and the frequency filtering, the angular band-gaps and the angular (spatial) filtering are also possible in photonic crystals. In this article, we review the recent advances of the spatial filtering using the photonic crystals in different propagation regimes and for different geometries. We review the most evident configuration of filtering in Bragg regime (with the back-reflection—i.e., in the configuration with band-gaps) as well as in Laue regime (with forward deflection—i.e., in the configuration without band-gaps). We explore the spatial filtering in crystals with different symmetries, including axisymmetric crystals; we discuss the role of chirping, i.e., the dependence of the longitudinal period along the structure. We also review the experimental techniques to fabricate the photonic crystals and numerical techniques to explore the spatial filtering. Finally, we discuss several implementations of such filters for intracavity spatial filtering.

  12. Singular perturbation of absolute stability.

    NASA Technical Reports Server (NTRS)

    Siljak, D. D.

    1972-01-01

    It was previously shown (author, 1969) that the regions of absolute stability in the parameter space can be determined when the parameters appear on the right-hand side of the system equations, i.e., the regular case. Here, the effect on absolute stability of a small parameter attached to higher derivatives in the equations (the singular case) is studied. The Lur'e-Postnikov class of nonlinear systems is considered.

  13. Photon-photon collisions

    SciTech Connect

    Brodsky, S.J.

    1985-01-01

    The study of photon-photon collisions has progressed enormously, stimulated by new data and new calculational tools for QCD. In the future we can expect precise determinations of ..cap alpha../sub s/ and ..lambda../sup ms/ from the ..gamma..*..gamma.. ..-->.. ..pi../sup 0/ form factor and the photon structure function, as well as detailed checks of QCD, determination of the shape of the hadron distribution amplitudes from ..gamma gamma.. ..-->.. H anti H, reconstruction of sigma/sub ..gamma gamma../ from exclusive channels at low W/sub ..gamma gamma../, definitive studies of high p/sub T/ hadron and jet production, and studies of threshold production of charmed systems. Photon-photon collisions, along with radiative decays of the psi and UPSILON, are ideal for the study of multiquark and gluonic resonances. We have emphasized the potential for resonance formation near threshold in virtually every hadronic exclusive channel, including heavy quark states c anti c c anti c, c anti c u anti u, etc. At higher energies SLC, LEP, ...) parity-violating electroweak effects and Higgs production due to equivalent Z/sup 0/ and W/sup + -/ beams from e ..-->.. eZ/sup 0/ and e ..-->.. nu W will become important. 44 references.

  14. Absolute Radiometric Calibration of KOMPSAT-3A

    NASA Astrophysics Data System (ADS)

    Ahn, H. Y.; Shin, D. Y.; Kim, J. S.; Seo, D. C.; Choi, C. U.

    2016-06-01

    This paper presents a vicarious radiometric calibration of the Korea Multi-Purpose Satellite-3A (KOMPSAT-3A) performed by the Korea Aerospace Research Institute (KARI) and the Pukyong National University Remote Sensing Group (PKNU RSG) in 2015.The primary stages of this study are summarized as follows: (1) A field campaign to determine radiometric calibrated target fields was undertaken in Mongolia and South Korea. Surface reflectance data obtained in the campaign were input to a radiative transfer code that predicted at-sensor radiance. Through this process, equations and parameters were derived for the KOMPSAT-3A sensor to enable the conversion of calibrated DN to physical units, such as at-sensor radiance or TOA reflectance. (2) To validate the absolute calibration coefficients for the KOMPSAT-3A sensor, we performed a radiometric validation with a comparison of KOMPSAT-3A and Landsat-8 TOA reflectance using one of the six PICS (Libya 4). Correlations between top-of-atmosphere (TOA) radiances and the spectral band responses of the KOMPSAT-3A sensors at the Zuunmod, Mongolia and Goheung, South Korea sites were significant for multispectral bands. The average difference in TOA reflectance between KOMPSAT-3A and Landsat-8 image over the Libya 4, Libya site in the red-green-blue (RGB) region was under 3%, whereas in the NIR band, the TOA reflectance of KOMPSAT-3A was lower than the that of Landsat-8 due to the difference in the band passes of two sensors. The KOMPSAT-3Aensor includes a band pass near 940 nm that can be strongly absorbed by water vapor and therefore displayed low reflectance. Toovercome this, we need to undertake a detailed analysis using rescale methods, such as the spectral bandwidth adjustment factor.

  15. Thulium-doped fiber laser utilizing a photonic crystal fiber-based optical low-pass filter with application in 1.7 μm and 1.8 μm band.

    PubMed

    Emami, Siamak Dawazdah; Khodaei, Amin; Gandan, Shumithira; Penny, Richard; Lim, Kok Sing; Abdul-Rashid, Hairul Azhar; Ahmad, Harith

    2015-07-27

    This paper describes a low pass filter based on photonics crystal fiber (PCF) partial ASE suppression, and its application within a 1.7 µm to 1.8 µm band thulium-doped fiber amplifier (TDFA) and a thulium-doped fiber laser (TDFL). The enlargement of air holes around the doped core region of the PCF resulted in a low-pass filter device that was able to attenuate wavelengths above the conventional long cut-off wavelength. These ensuing long cut-off wavelengths were 1.85 μm and 1.75 μm, and enabled a transmission mechanism that possessed a number of desirable characteristics. The proposed optical low-pass filter was applied within a TDFA and TDFL system. Peak spectrum was observed at around 1.9 μm for conventional TDF lasers, while the proposed TDF laser with PCF setup had fiber laser peak wavelengths measured at downshifted values of 1.74 μm and 1.81 μm. PMID:26367625

  16. Doppler-free two-photon excitation spectroscopy and the Zeeman effect of the 1401 band of the S1 1B2u<--S0 1A1g transition of benzene-d6

    NASA Astrophysics Data System (ADS)

    Wang, Jinguo; Doi, Atsushi; Kasahara, Shunji; Katô, Hajime; Baba, Masaaki

    2004-11-01

    The Doppler-free two-photon excitation spectrum and the Zeeman effect of the 1401 band of the S1←S0 transition of C6D6 were measured from 39 842 to 39 856 cm-1. The Zeeman splittings of the Q(K)Q(J) lines of a given J were observed to increase proportionally with K2 and reach a maximum at K=J. The Zeeman splittings of the Q(K=J)Q(J) lines were observed to increase proportionally with J. The observed Zeeman splittings are identified as originating from the electronic orbital angular momentum arising from a mixing of the S1 1B2u and S2 1B1u states via J-L coupling. No perturbation originating from an interaction with a triplet state was observed. It became clear from the Zeeman effect that rotationally resolved levels of the S1 state are not mixed with a triplet state. Therefore, it is concluded that nonradiative decay of an isolated benzene molecule excited to the S1 state occurs through the intramolecular vibrational-rotational mixing within the S1 state even in the low vibrational levels.

  17. Absolute irradiance of the Moon for on-orbit calibration

    USGS Publications Warehouse

    Stone, T.C.; Kieffer, H.H.; ,

    2002-01-01

    The recognized need for on-orbit calibration of remote sensing imaging instruments drives the ROLO project effort to characterize the Moon for use as an absolute radiance source. For over 5 years the ground-based ROLO telescopes have acquired spatially-resolved lunar images in 23 VNIR (Moon diameter ???500 pixels) and 9 SWIR (???250 pixels) passbands at phase angles within ??90 degrees. A numerical model for lunar irradiance has been developed which fits hundreds of ROLO images in each band, corrected for atmospheric extinction and calibrated to absolute radiance, then integrated to irradiance. The band-coupled extinction algorithm uses absorption spectra of several gases and aerosols derived from MODTRAN to fit time-dependent component abundances to nightly observations of standard stars. The absolute radiance scale is based upon independent telescopic measurements of the star Vega. The fitting process yields uncertainties in lunar relative irradiance over small ranges of phase angle and the full range of lunar libration well under 0.5%. A larger source of uncertainty enters in the absolute solar spectral irradiance, especially in the SWIR, where solar models disagree by up to 6%. Results of ROLO model direct comparisons to spacecraft observations demonstrate the ability of the technique to track sensor responsivity drifts to sub-percent precision. Intercomparisons among instruments provide key insights into both calibration issues and the absolute scale for lunar irradiance.

  18. Photonics with multiwall carbon nanotube arrays.

    PubMed

    Lidorikis, Elefterios; Ferrari, Andrea C

    2009-05-26

    We investigate the photonic properties of two-dimensional nanotube arrays for photon energies up to 40 eV and unveil the physics of two distinct applications: deep-UV photonic crystals and total visible absorbers. We find three main regimes: for small intertube spacing of 20-30 nm, we obtain strong Bragg scattering and photonic band gaps in the deep-UV range of 25 approximately 35 eV. For intermediate spacing of 40-100 nm, the photonic bands anticross with the graphite plasmon bands resulting into a complex photonic structure, and a generally reduced Bragg scattering. For large spacing >150 nm, the Bragg gap moves into the visible and decreases due to absorption. This leads to nanotube arrays behaving as total optical absorbers. Our results can guide the design of photonic applications in the visible and deep UV ranges.

  19. Dispersion in photonic crystals

    NASA Astrophysics Data System (ADS)

    Witzens, Jeremy

    2005-11-01

    Investigations on the dispersive properties of photonic crystals, modified scattering in ring-resonators, monolithic integration of vertical-cavity surface-emitting lasers and advanced data processing techniques for the finite-difference time-domain method are presented. Photonic crystals are periodic mesoscopic arrays of scatterers that modify the propagation properties of electromagnetic waves in a similar way as "natural" crystals modify the properties of electrons in solid-state physics. In this thesis photonic crystals are implemented as planar photonic crystals, i.e., optically thin semiconductor films with periodic arrays of holes etched into them, with a hole-to-hole spacing of the order of the wavelength of light in the dielectric media. Photonic crystals can feature forbidden frequency ranges (the band-gaps) in which light cannot propagate. Even though most work on photonic crystals has focused on these band-gaps for application such as confinement and guiding of light, this thesis focuses on the allowed frequency regions (the photonic bands) and investigates how the propagation of light is modified by the crystal lattice. In particular the guiding of light in bulk photonic crystals in the absence of lattice defects (the self-collimation effect) and the angular steering of light in photonic crystals (the superprism effect) are investigated. The latter is used to design a planar lightwave circuit for frequency domain demultiplexion. Difficulties such as efficient insertion of light into the crystal are resolved and previously predicted limitations on the resolution are circumvented. The demultiplexer is also fabricated and characterized. Monolithic integration of vertical-cavity surface-emitting lasers by means of resonantly enhanced grating couplers is investigated. The grating coupler is designed to bend light through a ninety-degree angle and is characterized with the finite-difference time-domain method. The vertical-cavity surface-emitting lasers are

  20. In-flight absolute radiometric calibration of the thematic mapper

    NASA Technical Reports Server (NTRS)

    Castle, K. R.; Holm, R. G.; Kastner, C. J.; Palmer, J. M.; Slater, P. N.; Dinguirard, M.; Ezra, C. E.; Jackson, R. D.; Savage, R. K.

    1983-01-01

    The TM multispectral scanner system was calibrated in an absolute manner before launch. To determine the temporal changes of the absolute radiometric calibration of the entire system, spectroradiometric measurements of the ground and the atmosphere were made simultaneously with TM collections over White Sands, New Mexico. By entering the measured values in an atmospheric radiative transfer program, the radiance levels of the in four of the spectral bands of the TM were determined. Tables show values for the reflectance of snow at White Sands measured by a modular 8 channel radiometer, and values for exoatmospheric irradiance within the TM passbands, calculated for the Earth-Sun distance using a solar radiometer.

  1. Absolute radiometric calibration of the CCRS SAR

    NASA Astrophysics Data System (ADS)

    Ulander, Lars M. H.; Hawkins, Robert K.; Livingstone, Charles E.; Lukowski, Tom I.

    1991-11-01

    Determining the radar scattering coefficients from SAR (synthetic aperture radar) image data requires absolute radiometric calibration of the SAR system. The authors describe an internal calibration methodology for the airborne Canada Centre for Remote Sensing (CCRS) SAR system, based on radar theory, a detailed model of the radar system, and measurements of system parameters. The methodology is verified by analyzing external calibration data acquired over a 6-month period in 1988 by the C-band radar using HH polarization. The results indicate that the overall error is +/- 0.8 dB (1-sigma) for incidence angles +/- 20 deg from antenna boresight. The dominant error contributions are due to the antenna radome and uncertainties in the elevation angle relative to the antenna boresight.

  2. Absolute flux scale for radioastronomy

    SciTech Connect

    Ivanov, V.P.; Stankevich, K.S.

    1986-07-01

    The authors propose and provide support for a new absolute flux scale for radio astronomy, which is not encumbered with the inadequacies of the previous scales. In constructing it the method of relative spectra was used (a powerful tool for choosing reference spectra). A review is given of previous flux scales. The authors compare the AIS scale with the scale they propose. Both scales are based on absolute measurements by the ''artificial moon'' method, and they are practically coincident in the range from 0.96 to 6 GHz. At frequencies above 6 GHz, 0.96 GHz, the AIS scale is overestimated because of incorrect extrapolation of the spectra of the primary and secondary standards. The major results which have emerged from this review of absolute scales in radio astronomy are summarized.

  3. Resonant photonic States in coupled heterostructure photonic crystal waveguides.

    PubMed

    Cox, Jd; Sabarinathan, J; Singh, Mr

    2010-01-01

    In this paper, we study the photonic resonance states and transmission spectra of coupled waveguides made from heterostructure photonic crystals. We consider photonic crystal waveguides made from three photonic crystals A, B and C, where the waveguide heterostructure is denoted as B/A/C/A/B. Due to the band structure engineering, light is confined within crystal A, which thus act as waveguides. Here, photonic crystal C is taken as a nonlinear photonic crystal, which has a band gap that may be modified by applying a pump laser. We have found that the number of bound states within the waveguides depends on the width and well depth of photonic crystal A. It has also been found that when both waveguides are far away from each other, the energies of bound photons in each of the waveguides are degenerate. However, when they are brought close to each other, the degeneracy of the bound states is removed due to the coupling between them, which causes these states to split into pairs. We have also investigated the effect of the pump field on photonic crystal C. We have shown that by applying a pump field, the system may be switched between a double waveguide to a single waveguide, which effectively turns on or off the coupling between degenerate states. This reveals interesting results that can be applied to develop new types of nanophotonic devices such as nano-switches and nano-transistors.

  4. Optics of globular photonic crystals

    SciTech Connect

    Gorelik, V S

    2007-05-31

    The results of experimental and theoretical studies of the optical properties of globular photonic crystals - new physical objects having a crystal structure with the lattice period exceeding considerably the atomic size, are presented. As globular photonic crystals, artificial opal matrices consisting of close-packed silica globules of diameter {approx}200 nm were used. The reflection spectra of these objects characterising the parameters of photonic bands existing in these crystals in the visible spectral region are presented. The idealised models of the energy band structure of photonic crystals investigated in the review give analytic dispersion dependences for the group velocity and the effective photon mass in a globular photonic crystal. The characteristics of secondary emission excited in globular photonic crystals by monochromatic and broadband radiation are presented. The results of investigations of single-photon-excited delayed scattering of light observed in globular photonic crystals exposed to cw UV radiation and radiation from a repetitively pulsed copper vapour laser are presented. The possibilities of using globular photonic crystals as active media for lasing in different spectral regions are considered. It is proposed to use globular photonic crystals as sensitive sensors in optoelectronic devices for molecular analysis of organic and inorganic materials by the modern methods of laser spectroscopy. The results of experimental studies of spontaneous and stimulated globular scattering of light are discussed. The conditions for observing resonance and two-photon-excited delayed scattering of light are found. The possibility of accumulation and localisation of the laser radiation energy inside a globular photonic crystal is reported. (review)

  5. Relativistic Absolutism in Moral Education.

    ERIC Educational Resources Information Center

    Vogt, W. Paul

    1982-01-01

    Discusses Emile Durkheim's "Moral Education: A Study in the Theory and Application of the Sociology of Education," which holds that morally healthy societies may vary in culture and organization but must possess absolute rules of moral behavior. Compares this moral theory with current theory and practice of American educators. (MJL)

  6. Absolute transition probabilities of phosphorus.

    NASA Technical Reports Server (NTRS)

    Miller, M. H.; Roig, R. A.; Bengtson, R. D.

    1971-01-01

    Use of a gas-driven shock tube to measure the absolute strengths of 21 P I lines and 126 P II lines (from 3300 to 6900 A). Accuracy for prominent, isolated neutral and ionic lines is estimated to be 28 to 40% and 18 to 30%, respectively. The data and the corresponding theoretical predictions are examined for conformity with the sum rules.-

  7. In-flight Absolute Radiometric Calibration of the Thematic Mapper

    NASA Technical Reports Server (NTRS)

    Castle, K. R.; Holm, R. G.; Kastner, C. J.; Palmer, J. M.; Slater, P. N.; Dinguirard, M.; Ezra, C. E.; Jackson, D.; Savage, R. K.

    1984-01-01

    The Thematic Mapper (TM) multispectral scanner system was placed into Earth orbit on July 16, 1982, as part of NASA's LANDSAT 4 payload. To determine temporal changes of the absolute radiometric calibration of the entire system in flight, spectroradiometric measurements of the ground and the atmosphere are made simultaneously with TM image acquisitions over the White Sands, New Mexico area. By entering the measured values into an atmospheric radiative transfer program, the radiance levels at the entrance pupil of the TM in four of the TM spectral bands are determined. These levels are compared to the output digital counts from the detectors that sampled the radiometrically measured ground area, thus providing an absolute radiometric calibration of the entire TM system utilizing those detectors. By reference to an adjacent, larger uniform area, the calibration is extended to all 16 detectors in each of the three bands.

  8. Prelaunch absolute radiometric calibration of LANDSAT-4 protoflight Thematic Mapper

    NASA Technical Reports Server (NTRS)

    Barker, J. L.; Ball, D. L.; Leung, K. C.; Walker, J. A.

    1984-01-01

    Results are summarized and analyzed from several prelaunch tests with a 122 cm integrating sphere used as part of the absolute radiometric calibration experiments for the protoflight TM sensor carried on the LANDSAT-4 satellite. The calibration procedure is presented and the radiometric sensitivity of the TM is assessed. The internal calibrator and dynamic range after calibration are considered. Tables show dynamic range after ground processing, spectral radiance to digital number and digital number to spectral radiance values for TM bands 1, 2, 3, 4, 5, 7 and for channel 4 of band 6.

  9. Optomechanics for absolute rotation detection

    NASA Astrophysics Data System (ADS)

    Davuluri, Sankar

    2016-07-01

    In this article, we present an application of optomechanical cavity for the absolute rotation detection. The optomechanical cavity is arranged in a Michelson interferometer in such a way that the classical centrifugal force due to rotation changes the length of the optomechanical cavity. The change in the cavity length induces a shift in the frequency of the cavity mode. The phase shift corresponding to the frequency shift in the cavity mode is measured at the interferometer output to estimate the angular velocity of absolute rotation. We derived an analytic expression to estimate the minimum detectable rotation rate in our scheme for a given optomechanical cavity. Temperature dependence of the rotation detection sensitivity is studied.

  10. Moral absolutism and ectopic pregnancy.

    PubMed

    Kaczor, C

    2001-02-01

    If one accepts a version of absolutism that excludes the intentional killing of any innocent human person from conception to natural death, ectopic pregnancy poses vexing difficulties. Given that the embryonic life almost certainly will die anyway, how can one retain one's moral principle and yet adequately respond to a situation that gravely threatens the life of the mother and her future fertility? The four options of treatment most often discussed in the literature are non-intervention, salpingectomy (removal of tube with embryo), salpingostomy (removal of embryo alone), and use of methotrexate (MXT). In this essay, I review these four options and introduce a fifth (the milking technique). In order to assess these options in terms of the absolutism mentioned, it will also be necessary to discuss various accounts of the intention/foresight distinction. I conclude that salpingectomy, salpingostomy, and the milking technique are compatible with absolutist presuppositions, but not the use of methotrexate.

  11. Moral absolutism and ectopic pregnancy.

    PubMed

    Kaczor, C

    2001-02-01

    If one accepts a version of absolutism that excludes the intentional killing of any innocent human person from conception to natural death, ectopic pregnancy poses vexing difficulties. Given that the embryonic life almost certainly will die anyway, how can one retain one's moral principle and yet adequately respond to a situation that gravely threatens the life of the mother and her future fertility? The four options of treatment most often discussed in the literature are non-intervention, salpingectomy (removal of tube with embryo), salpingostomy (removal of embryo alone), and use of methotrexate (MXT). In this essay, I review these four options and introduce a fifth (the milking technique). In order to assess these options in terms of the absolutism mentioned, it will also be necessary to discuss various accounts of the intention/foresight distinction. I conclude that salpingectomy, salpingostomy, and the milking technique are compatible with absolutist presuppositions, but not the use of methotrexate. PMID:11262641

  12. The Absolute Spectrum Polarimeter (ASP)

    NASA Technical Reports Server (NTRS)

    Kogut, A. J.

    2010-01-01

    The Absolute Spectrum Polarimeter (ASP) is an Explorer-class mission to map the absolute intensity and linear polarization of the cosmic microwave background and diffuse astrophysical foregrounds over the full sky from 30 GHz to 5 THz. The principal science goal is the detection and characterization of linear polarization from an inflationary epoch in the early universe, with tensor-to-scalar ratio r much greater than 1O(raised to the power of { -3}) and Compton distortion y < 10 (raised to the power of{-6}). We describe the ASP instrument and mission architecture needed to detect the signature of an inflationary epoch in the early universe using only 4 semiconductor bolometers.

  13. Classification images predict absolute efficiency.

    PubMed

    Murray, Richard F; Bennett, Patrick J; Sekuler, Allison B

    2005-02-24

    How well do classification images characterize human observers' strategies in perceptual tasks? We show mathematically that from the classification image of a noisy linear observer, it is possible to recover the observer's absolute efficiency. If we could similarly predict human observers' performance from their classification images, this would suggest that the linear model that underlies use of the classification image method is adequate over the small range of stimuli typically encountered in a classification image experiment, and that a classification image captures most important aspects of human observers' performance over this range. In a contrast discrimination task and in a shape discrimination task, we found that observers' absolute efficiencies were generally well predicted by their classification images, although consistently slightly (approximately 13%) higher than predicted. We consider whether a number of plausible nonlinearities can account for the slight under prediction, and of these we find that only a form of phase uncertainty can account for the discrepancy.

  14. Absolute calibration of optical flats

    DOEpatents

    Sommargren, Gary E.

    2005-04-05

    The invention uses the phase shifting diffraction interferometer (PSDI) to provide a true point-by-point measurement of absolute flatness over the surface of optical flats. Beams exiting the fiber optics in a PSDI have perfect spherical wavefronts. The measurement beam is reflected from the optical flat and passed through an auxiliary optic to then be combined with the reference beam on a CCD. The combined beams include phase errors due to both the optic under test and the auxiliary optic. Standard phase extraction algorithms are used to calculate this combined phase error. The optical flat is then removed from the system and the measurement fiber is moved to recombine the two beams. The newly combined beams include only the phase errors due to the auxiliary optic. When the second phase measurement is subtracted from the first phase measurement, the absolute phase error of the optical flat is obtained.

  15. The low-energy photon tagger NEPTUN

    NASA Astrophysics Data System (ADS)

    Savran, D.; Lindenberg, K.; Glorius, J.; Löher, B.; Müller, S.; Pietralla, N.; Schnorrenberger, L.; Simon, V.; Sonnabend, K.; Wälzlein, C.; Elvers, M.; Endres, J.; Hasper, J.; Zilges, A.

    2010-02-01

    A new photon tagging spectrometer was built at the superconducting Darmstadt electron linear accelerator (S-DALINAC). The system is designed for tagging photons in an energy range from 6 to 20 MeV with the emphasis on best possible energy resolution and intensity. The absolute energy resolution of photons at 10 MeV is expected to be about 20 keV. With scintillating fibres as focal-plane detectors a maximum rate of tagged photons of 104 keV -1s -1 will be achieved. Detailed design studies including Monte Carlo simulations are presented, as well as results for the measured tagged photon energy profile of the system realized so far. This photon-tagging facility will allow to determine the photon absorption cross-sections as a function of excitation energy and to study the decay patterns of nuclear photo-excitations in great detail.

  16. New Kronig-Penney Equation Emphasizing the Band Edge Conditions

    ERIC Educational Resources Information Center

    Szmulowicz, Frank

    2008-01-01

    The Kronig-Penney problem is a textbook example for discussing band dispersions and band gap formation in periodic layered media. For example, in photonic crystals, the behaviour of bands next to the band edges is important for further discussions of such effects as inhibited light emission, slow light and negative index of refraction. However,…

  17. MEASURING TEMPORAL PHOTON BUNCHING IN BLACKBODY RADIATION

    SciTech Connect

    Tan, P. K.; Poh, H. S.; Kurtsiefer, C.; Yeo, G. H.; Chan, A. H. E-mail: phyck@nus.edu.sg

    2014-07-01

    Light from thermal blackbody radiators such as stars exhibits photon bunching behavior at sufficiently short timescales. However, with available detector bandwidths, this bunching signal is difficult to observe directly. We present an experimental technique to increase the photon bunching signal in blackbody radiation via spectral filtering of the light source. Our measurements reveal strong temporal photon bunching from blackbody radiation, including the Sun. This technique allows for an absolute measurement of the photon bunching signature g {sup (2)}(0), and thereby a direct statement on the statistical nature of a light source. Such filtering techniques may help revive the interest in intensity interferometry as a tool in astronomy.

  18. Photonic crystal optical memory

    NASA Astrophysics Data System (ADS)

    Lima, A. Wirth; Sombra, A. S. B.

    2011-06-01

    After several decades pushing the technology and the development of the world, the electronics is giving space for technologies that use light. We propose and analyze an optical memory embedded in a nonlinear photonic crystal (PhC), whose system of writing and reading data is controlled by an external command signal. This optical memory is based on optical directional couplers connected to a shared optical ring. Such a device can work over the C-Band of ITU (International Telecommunication Union).

  19. Absolute standardization of the impurity (121)Te associated to the production of the radiopharmaceutical (123)I.

    PubMed

    Araújo, M T F; Poledna, R; Delgado, J U; Silva, R L; Iwahara, A; da Silva, C J; Tauhata, L; Oliveira, A E; de Almeida, M C M; Lopes, R T

    2016-03-01

    (123)I is widely used for radiodiagnostic procedures. It is produced by reaction of (124)Xe (p,2n) (123)Cs →(123)Xe →(123)I in cyclotrons. (121)Te and (125)I appear in a photon energy spectrum as impurities. An activity of (121)Te was calibrated absolutely by sum-peak method and its photon emitting probability was estimated, whose results were consistent with published results. PMID:26805708

  20. The speed of light perturbation in absolute gravimeters from the viewpoint of ‘relativistic geometry’

    NASA Astrophysics Data System (ADS)

    Shao, Cheng-Gang; Tan, Yu-Jie; Li, Jia; Hu, Zhong-Kun

    2015-04-01

    In the past few years, the perturbation due to the finite speed of light was among the most inconsistent in corner-cube absolute gravimeters. For the relativistic treatment of the perturbation based on Lorentz transformation, the relation between Doppler shift in special relativity and time delay in classical domain is easily misunderstood, leading to spurious conclusions. To avoid these issues, we apply a ‘relativistic geometrical method’ based on the motion of photons to calculate the frequency shift in corner-cube absolute gravimeters, where the misunderstood relation has been corrected. Additionally, we find that the modern corner-cube absolute gravimeters cannot sense effects of the special relativity.

  1. Absolute calibration of space-resolving soft X-ray spectrograph for plasma diagnostics

    NASA Astrophysics Data System (ADS)

    Yoshikawa, M.; Okamoto, Y.; Kawamori, E.; Watanabe, Y.; Watabe, C.; Yamaguchi, N.; Tamano, T.

    2001-07-01

    A grazing incidence flat-field soft X-ray (20-350 Å) spectrograph was constructed and applied for impurity diagnostics in the GAMMA 10 fusion plasma. The spectrograph consisted of a limited height entrance slit, an aberration-corrected concave grating, a microchannel-plate intensified detector and an instant camera/a high speed solid state camera. An absolute calibration experiment for the SX spectrograph was performed at the Photon Factory in the High Energy Accelerator Research Organization with monitoring the incident synchrotron beam intensity by using an absolutely calibrated XUV silicon photodiode. From the results of absolute calibration of the spectrograph, the radiation loss from the plasma was obtained.

  2. Nuclear photonics

    SciTech Connect

    Habs, D.; Guenther, M. M.; Jentschel, M.; Thirolf, P. G.

    2012-07-09

    With the planned new {gamma}-beam facilities like MEGa-ray at LLNL (USA) or ELI-NP at Bucharest (Romania) with 10{sup 13}{gamma}/s and a band width of {Delta}E{gamma}/E{gamma} Almost-Equal-To 10{sup -3}, a new era of {gamma} beams with energies up to 20MeV comes into operation, compared to the present world-leading HI{gamma}S facility at Duke University (USA) with 10{sup 8}{gamma}/s and {Delta}E{gamma}/E{gamma} Almost-Equal-To 3 Dot-Operator 10{sup -2}. In the long run even a seeded quantum FEL for {gamma} beams may become possible, with much higher brilliance and spectral flux. At the same time new exciting possibilities open up for focused {gamma} beams. Here we describe a new experiment at the {gamma} beam of the ILL reactor (Grenoble, France), where we observed for the first time that the index of refraction for {gamma} beams is determined by virtual pair creation. Using a combination of refractive and reflective optics, efficient monochromators for {gamma} beams are being developed. Thus, we have to optimize the total system: the {gamma}-beam facility, the {gamma}-beam optics and {gamma} detectors. We can trade {gamma} intensity for band width, going down to {Delta}E{gamma}/E{gamma} Almost-Equal-To 10{sup -6} and address individual nuclear levels. The term 'nuclear photonics' stresses the importance of nuclear applications. We can address with {gamma}-beams individual nuclear isotopes and not just elements like with X-ray beams. Compared to X rays, {gamma} beams can penetrate much deeper into big samples like radioactive waste barrels, motors or batteries. We can perform tomography and microscopy studies by focusing down to {mu}m resolution using Nuclear Resonance Fluorescence (NRF) for detection with eV resolution and high spatial resolution at the same time. We discuss the dominating M1 and E1 excitations like the scissors mode, two-phonon quadrupole octupole excitations, pygmy dipole excitations or giant dipole excitations under the new facet of

  3. Nuclear photonics

    NASA Astrophysics Data System (ADS)

    Habs, D.; Günther, M. M.; Jentschel, M.; Thirolf, P. G.

    2012-07-01

    With the planned new γ-beam facilities like MEGa-ray at LLNL (USA) or ELI-NP at Bucharest (Romania) with 1013 γ/s and a band width of ΔEγ/Eγ≈10-3, a new era of γ beams with energies up to 20MeV comes into operation, compared to the present world-leading HIγS facility at Duke University (USA) with 108 γ/s and ΔEγ/Eγ≈3ṡ10-2. In the long run even a seeded quantum FEL for γ beams may become possible, with much higher brilliance and spectral flux. At the same time new exciting possibilities open up for focused γ beams. Here we describe a new experiment at the γ beam of the ILL reactor (Grenoble, France), where we observed for the first time that the index of refraction for γ beams is determined by virtual pair creation. Using a combination of refractive and reflective optics, efficient monochromators for γ beams are being developed. Thus, we have to optimize the total system: the γ-beam facility, the γ-beam optics and γ detectors. We can trade γ intensity for band width, going down to ΔEγ/Eγ≈10-6 and address individual nuclear levels. The term "nuclear photonics" stresses the importance of nuclear applications. We can address with γ-beams individual nuclear isotopes and not just elements like with X-ray beams. Compared to X rays, γ beams can penetrate much deeper into big samples like radioactive waste barrels, motors or batteries. We can perform tomography and microscopy studies by focusing down to μm resolution using Nuclear Resonance Fluorescence (NRF) for detection with eV resolution and high spatial resolution at the same time. We discuss the dominating M1 and E1 excitations like the scissors mode, two-phonon quadrupole octupole excitations, pygmy dipole excitations or giant dipole excitations under the new facet of applications. We find many new applications in biomedicine, green energy, radioactive waste management or homeland security. Also more brilliant secondary beams of neutrons and positrons can be produced.

  4. High precision photon flux determination for photon tagging experiments

    SciTech Connect

    Teymurazyan, A; Ahmidouch, A; Ambrozewicz, P; Asratyan, A; Baker, K; Benton, L; Burkert, V; Clinton, E; Cole, P; Collins, P; Dale, D; Danagoulian, S; Davidenko, G; Demirchyan, R; Deur, A; Dolgolenko, A; Dzyubenko, G; Ent, R; Evdokimov, A; Feng, J; Gabrielyan, M; Gan, L; Gasparian, A; Glamazdin, A; Goryachev, V; Hardy, K; He, J; Ito, M; Jiang, L; Kashy, D; Khandaker, M; Kolarkar, A; Konchatnyi, M; Korchin, A; Korsch, W; Kosinov, O; Kowalski, S; Kubantsev, M; Kubarovsky, V; Larin, I; Lawrence, D; Li, X; Martel, P; Matveev, V; McNulty, D; Mecking, B; Milbrath, B; Minehart, R; Miskimen, R; Mochalov, V; Nakagawa, I; Overby, S; Pasyuk, E; Payen, M; Pedroni, R; Prok, Y; Ritchie, B; Salgado, C; Shahinyan, A; Sitnikov, A; Sober, D; Stepanyan, S; Stevens, W; Underwood, J; Vasiliev, A; Vishnyakov, V; Wood, M; Zhou, S

    2014-07-01

    The Jefferson Laboratory PrimEx Collaboration has developed and implemented a method to control the tagged photon flux in photoproduction experiments at the 1% level over the photon energy range from 4.9 to 5.5 GeV. This method has been successfully implemented in a high precision measurement of the neutral pion lifetime. Here, we outline the experimental equipment and the analysis techniques used to accomplish this. These include the use of a total absorption counter for absolute flux calibration, a pair spectrometer for online relative flux monitoring, and a new method for post-bremsstrahlung electron counting.

  5. Absolute measurement of the extreme UV solar flux

    NASA Technical Reports Server (NTRS)

    Carlson, R. W.; Ogawa, H. S.; Judge, D. L.; Phillips, E.

    1984-01-01

    A windowless rare-gas ionization chamber has been developed to measure the absolute value of the solar extreme UV flux in the 50-575-A region. Successful results were obtained on a solar-pointing sounding rocket. The ionization chamber, operated in total absorption, is an inherently stable absolute detector of ionizing UV radiation and was designed to be independent of effects from secondary ionization and gas effusion. The net error of the measurement is + or - 7.3 percent, which is primarily due to residual outgassing in the instrument, other errors such as multiple ionization, photoelectron collection, and extrapolation to the zero atmospheric optical depth being small in comparison. For the day of the flight, Aug. 10, 1982, the solar irradiance (50-575 A), normalized to unit solar distance, was found to be 5.71 + or - 0.42 x 10 to the 10th photons per sq cm sec.

  6. Two-photon interferences with degenerate and nondegenerate paired photons

    NASA Astrophysics Data System (ADS)

    Liu, Chang; Chen, J. F.; Zhang, Shanchao; Zhou, Shuyu; Kim, Yoon-Ho; Loy, M. M. T.; Wong, G. K. L.; Du, Shengwang

    2012-02-01

    We generate narrow-band frequency-tunable entangled photon pairs from spontaneous four-wave mixing in three-level cold atoms and study their two-photon quantum interference after a beam splitter. We find that the path-exchange symmetry plays a more important role in the Hong-Ou-Mandel interference than the temporal or frequency indistinguishability, and observe coalescence interference for both degenerate and nondegenerate photons. We also observe a quantum beat in the same experimental setup using either slow or fast detectors.

  7. Providing reference standards and metrology for the few photon-photon counting community

    NASA Astrophysics Data System (ADS)

    Beaumont, Andrew R.; Cheung, Jessica Y.; Chunnilall, Christopher J.; Ireland, Jane; White, Malcolm G.

    2009-10-01

    The main drivers for developing few-photon metrological techniques are the rapidly progressing field of quantum information processing, which requires the development of high-efficiency photon-counting detectors, and the wider use of photon-counting technology in biology, medical physics and nuclear physics. This paper will focus on the provision of standards for the few photon community and the development of techniques for the characterisation of photon-counting detectors. At the high-power end, microwatts, we are developing a low-power absolute radiometer as a primary standard that will be used to provide traceability over a much broader spectral range. At the few photon-photon-counting level we are developing a conventional calibration technique, which is traceable to the primary standard through a reference trap detector. This method can be used in both analogue and photon-counting modes and provides a convenient route for providing customer calibration at few-photon levels across the optical spectrum. At the photon-counting/single-photon level we are developing a technique based on correlated photons. These are produced via parametric downconversion and can be used to measure directly the detection efficiency of photon-counting detectors. A cross-validation of the correlated photon and conventional technique is reported. Finally we discuss this work in the context of an EU project, that is aimed at establishing the route towards the re-definition of the candela, the SI unit for optical radiation.

  8. Photonic module: An on-demand resource for photonic entanglement

    SciTech Connect

    Devitt, Simon J.; Greentree, Andrew D.; Hollenberg, Lloyd C. L.; Ionicioiu, Radu; O'Brien, Jeremy L.; Munro, William J.

    2007-11-15

    Photonic entanglement has a wide range of applications in quantum computation and communication. Here we introduce a device: the photonic module, which allows for the rapid, deterministic preparation of a large class of entangled photon states. The module is an application independent, ''plug and play'' device, with sufficient flexibility to prepare entanglement for all major quantum computation and communication applications in a completely deterministic fashion without number-discriminated photon detection. We present two alternative constructions for the module, one using free-space components and one in a photonic band-gap structure. The natural operation of the module is to generate states within the stabilizer formalism and we present an analysis on the cavity requirements to experimentally realize this device.

  9. The AFGL absolute gravity program

    NASA Technical Reports Server (NTRS)

    Hammond, J. A.; Iliff, R. L.

    1978-01-01

    A brief discussion of the AFGL's (Air Force Geophysics Laboratory) program in absolute gravity is presented. Support of outside work and in-house studies relating to gravity instrumentation are discussed. A description of the current transportable system is included and the latest results are presented. These results show good agreement with measurements at the AFGL site by an Italian system. The accuracy obtained by the transportable apparatus is better than 0.1 microns sq sec 10 microgal and agreement with previous measurements is within the combined uncertainties of the measurements.

  10. Familial Aggregation of Absolute Pitch

    PubMed Central

    Baharloo, Siamak; Service, Susan K.; Risch, Neil; Gitschier, Jane; Freimer, Nelson B.

    2000-01-01

    Absolute pitch (AP) is a behavioral trait that is defined as the ability to identify the pitch of tones in the absence of a reference pitch. AP is an ideal phenotype for investigation of gene and environment interactions in the development of complex human behaviors. Individuals who score exceptionally well on formalized auditory tests of pitch perception are designated as “AP-1.” As described in this report, auditory testing of siblings of AP-1 probands and of a control sample indicates that AP-1 aggregates in families. The implications of this finding for the mapping of loci for AP-1 predisposition are discussed. PMID:10924408

  11. Partial confinement photonic crystal waveguides

    SciTech Connect

    Saini, S.; Hong, C.-Y.; Pfaff, N.; Kimerling, L. C.; Michel, J.

    2008-12-29

    One-dimensional photonic crystal waveguides with an incomplete photonic band gap are modeled and proposed for an integration application that exploits their property of partial angular confinement. Planar apodized photonic crystal structures are deposited by plasma enhanced chemical vapor deposition and characterized by reflectivity as a function of angle and polarization, validating a partial confinement design for light at 850 nm wavelength. Partial confinement identifies an approach for tailoring waveguide properties by the exploitation of conformal film deposition over a substrate with angularly dependent topology. An application for an optoelectronic transceiver is demonstrated.

  12. Landsat-7 ETM+ radiometric stability and absolute calibration

    USGS Publications Warehouse

    Markham, B.L.; Barker, J.L.; Barsi, J.A.; Kaita, E.; Thome, K.J.; Helder, D.L.; Palluconi, Frank Don; Schott, J.R.; Scaramuzza, P.; ,

    2002-01-01

    Launched in April 1999, the Landsat-7 ETM+ instrument is in its fourth year of operation. The quality of the acquired calibrated imagery continues to be high, especially with respect to its three most important radiometric performance parameters: reflective band instrument stability to better than ??1%, reflective band absolute calibration to better than ??5%, and thermal band absolute calibration to better than ??0.6 K. The ETM+ instrument has been the most stable of any of the Landsat instruments, in both the reflective and thermal channels. To date, the best on-board calibration source for the reflective bands has been the Full Aperture Solar Calibrator, which has indicated changes of at most -1.8% to -2.0% (95% C.I.) change per year in the ETM+ gain (band 4). However, this change is believed to be caused by changes in the solar diffuser panel, as opposed to a change in the instrument's gain. This belief is based partially on ground observations, which bound the changes in gain in band 4 at -0.7% to +1.5%. Also, ETM+ stability is indicated by the monitoring of desert targets. These image-based results for four Saharan and Arabian sites, for a collection of 35 scenes over the three years since launch, bound the gain change at -0.7% to +0.5% in band 4. Thermal calibration from ground observations revealed an offset error of +0.31 W/m 2 sr um soon after launch. This offset was corrected within the U. S. ground processing system at EROS Data Center on 21-Dec-00, and since then, the band 6 on-board calibration has indicated changes of at most +0.02% to +0.04% (95% C.I.) per year. The latest ground observations have detected no remaining offset error with an RMS error of ??0.6 K. The stability and absolute calibration of the Landsat-7 ETM+ sensor make it an ideal candidate to be used as a reference source for radiometric cross-calibrating to other land remote sensing satellite systems.

  13. Landsat-7 ETM+ radiometric stability and absolute calibration

    NASA Astrophysics Data System (ADS)

    Markham, Brian L.; Barker, John L.; Barsi, Julia A.; Kaita, Ed; Thome, Kurtis J.; Helder, Dennis L.; Palluconi, Frank D.; Schott, John R.; Scaramuzza, Pat

    2003-04-01

    Launched in April 1999, the Landsat-7 ETM+ instrument is in its fourth year of operation. The quality of the acquired calibrated imagery continues to be high, especially with respect to its three most important radiometric performance parameters: reflective band instrument stability to better than +/-1%, reflective band absolute calibration to better than +/-5%, and thermal band absolute calibration to better than +/- 0.6 K. The ETM+ instrument has been the most stable of any of the Landsat instruments, in both the reflective and thermal channels. To date, the best on-board calibration source for the reflective bands has been the Full Aperture Solar Calibrator, which has indicated changes of at most -1.8% to -2.0% (95% C.I.) change per year in the ETM+ gain (band 4). However, this change is believed to be caused by changes in the solar diffuser panel, as opposed to a change in the instrument's gain. This belief is based partially on ground observations, which bound the changes in gain in band 4 at -0.7% to +1.5%. Also, ETM+ stability is indicated by the monitoring of desert targets. These image-based results for four Saharan and Arabian sites, for a collection of 35 scenes over the three years since launch, bound the gain change at -0.7% to +0.5% in band 4. Thermal calibration from ground observations revealed an offset error of +0.31 W/m2 sr um soon after launch. This offset was corrected within the U. S. ground processing system at EROS Data Center on 21-Dec-00, and since then, the band 6 on-board calibration has indicated changes of at most +0.02% to +0.04% (95% C.I.) per year. The latest ground observations have detected no remaining offset error with an RMS error of +/- 0.6 K. The stability and absolute calibration of the Landsat-7 ETM+ sensor make it an ideal candidate to be used as a reference source for radiometric cross-calibrating to other land remote sensing satellite systems.

  14. Topological photonic crystal with equifrequency Weyl points

    NASA Astrophysics Data System (ADS)

    Wang, Luyang; Jian, Shao-Kai; Yao, Hong

    2016-06-01

    Weyl points in three-dimensional photonic crystals behave as monopoles of Berry flux in momentum space. Here, based on general symmetry analysis, we show that a minimal number of four symmetry-related (consequently equifrequency) Weyl points can be realized in time-reversal invariant photonic crystals. We further propose an experimentally feasible way to modify double-gyroid photonic crystals to realize four equifrequency Weyl points, which is explicitly confirmed by our first-principle photonic band-structure calculations. Remarkably, photonic crystals with equifrequency Weyl points are qualitatively advantageous in applications including angular selectivity, frequency selectivity, invisibility cloaking, and three-dimensional imaging.

  15. Topological photonic crystal with ideal Weyl points

    NASA Astrophysics Data System (ADS)

    Wang, Luyang; Jian, Shao-Kai; Yao, Hong

    Weyl points in three-dimensional photonic crystals behave as monopoles of Berry flux in momentum space. Here, based on symmetry analysis, we show that a minimal number of symmetry-related Weyl points can be realized in time-reversal invariant photonic crystals. We propose to realize these ``ideal'' Weyl points in modified double-gyroid photonic crystals, which is confirmed by our first-principle photonic band-structure calculations. Photonic crystals with ideal Weyl points are qualitatively advantageous in applications such as angular and frequency selectivity, broadband invisibility cloaking, and broadband 3D-imaging.

  16. Nonlinear silicon photonics

    NASA Astrophysics Data System (ADS)

    Tsia, Kevin K.; Jalali, Bahram

    2010-05-01

    An intriguing optical property of silicon is that it exhibits a large third-order optical nonlinearity, with orders-ofmagnitude larger than that of silica glass in the telecommunication band. This allows efficient nonlinear optical interaction at relatively low power levels in a small footprint. Indeed, we have witnessed a stunning progress in harnessing the Raman and Kerr effects in silicon as the mechanisms for enabling chip-scale optical amplification, lasing, and wavelength conversion - functions that until recently were perceived to be beyond the reach of silicon. With all the continuous efforts developing novel techniques, nonlinear silicon photonics is expected to be able to reach even beyond the prior achievements. Instead of providing a comprehensive overview of this field, this manuscript highlights a number of new branches of nonlinear silicon photonics, which have not been fully recognized in the past. In particular, they are two-photon photovoltaic effect, mid-wave infrared (MWIR) silicon photonics, broadband Raman effects, inverse Raman scattering, and periodically-poled silicon (PePSi). These novel effects and techniques could create a new paradigm for silicon photonics and extend its utility beyond the traditionally anticipated applications.

  17. Photon absorptiometry

    SciTech Connect

    Velchik, M.G.

    1987-01-01

    Recently, there has been a renewed interest in the detection and treatment of osteoporosis. This paper is a review of the merits and limitations of the various noninvasive modalities currently available for the measurement of bone mineral density with special emphasis placed upon the nuclear medicine techniques of single-photon and dual-photon absorptiometry. The clinicians should come away with an understanding of the relative advantages and disadvantages of photon absorptiometry and its optimal clinical application. 49 references.

  18. Gastric Banding

    MedlinePlus

    ... gastric banding before deciding to have the procedure. Advertisements for a device or procedure may not include ... feeds Follow FDA on Twitter Follow FDA on Facebook View FDA videos on YouTube View FDA photos ...

  19. L(alpha)-induced two-photon absorption of visible light emitted from an O-type star by H2(+) ions located near the surface of the Stromgren sphere surrounding the star: A possible explanation for the diffuse interstellar absorption bands (DIDs)

    NASA Technical Reports Server (NTRS)

    Glownia, James H.; Sorokin, Peter P.

    1994-01-01

    In this paper, a new model is proposed to account for the DIB's (Diffuse Interstellar Bands). In this model, the DIB's result from a non-linear effect: resonantly-enhanced two-photon absorption of H(2+) ions located near the surface of the Stromgren sphere that surrounds an O- or B- type star. The strong light that is required to 'drive' the two-photon transition is provided by L(alpha) light emerging from the Stromgren sphere that bounds the H II region surrounding the star. A value of approximately 100 micro W/sq cm is estimated for the L(alpha) flux at the Stromgren radius, R(s), of a strong (O5) star. It is shown that a c.w. L(alpha) flux of this intensity should be sufficient to induce a few percent absorption for visible light radiated by the same star at a frequency (omega2) that completes an allowed two-photon transition, provided (1) the L(alpha) radiation happens to be nearly resonant with the frequency of a fully-allowed absorber transition that effectively represents the first step in the two-photon transition, and (2) an effective column density approximately 10(sup18)/sq cm of the absorber is present near the Stromgren sphere radius, R(sub s).

  20. Thermally tunable ferroelectric thin film photonic crystals.

    SciTech Connect

    Lin, P. T.; Wessels, B. W.; Imre, A.; Ocola, L. E.; Northwestern Univ.

    2008-01-01

    Thermally tunable PhCs are fabricated from ferroelectric thin films. Photonic band structure and temperature dependent diffraction are calculated by FDTD. 50% intensity modulation is demonstrated experimentally. This device has potential in active ultra-compact optical circuits.

  1. Cosmology with negative absolute temperatures

    NASA Astrophysics Data System (ADS)

    Vieira, J. P. P.; Byrnes, Christian T.; Lewis, Antony

    2016-08-01

    Negative absolute temperatures (NAT) are an exotic thermodynamical consequence of quantum physics which has been known since the 1950's (having been achieved in the lab on a number of occasions). Recently, the work of Braun et al. [1] has rekindled interest in negative temperatures and hinted at a possibility of using NAT systems in the lab as dark energy analogues. This paper goes one step further, looking into the cosmological consequences of the existence of a NAT component in the Universe. NAT-dominated expanding Universes experience a borderline phantom expansion (w < ‑1) with no Big Rip, and their contracting counterparts are forced to bounce after the energy density becomes sufficiently large. Both scenarios might be used to solve horizon and flatness problems analogously to standard inflation and bouncing cosmologies. We discuss the difficulties in obtaining and ending a NAT-dominated epoch, and possible ways of obtaining density perturbations with an acceptable spectrum.

  2. Apparatus for absolute pressure measurement

    NASA Technical Reports Server (NTRS)

    Hecht, R. (Inventor)

    1969-01-01

    An absolute pressure sensor (e.g., the diaphragm of a capacitance manometer) was subjected to a superimposed potential to effectively reduce the mechanical stiffness of the sensor. This substantially increases the sensitivity of the sensor and is particularly useful in vacuum gauges. An oscillating component of the superimposed potential induced vibrations of the sensor. The phase of these vibrations with respect to that of the oscillating component was monitored, and served to initiate an automatic adjustment of the static component of the superimposed potential, so as to bring the sensor into resonance at the frequency of the oscillating component. This establishes a selected sensitivity for the sensor, since a definite relationship exists between resonant frequency and sensitivity.

  3. Cosmology with negative absolute temperatures

    NASA Astrophysics Data System (ADS)

    Vieira, J. P. P.; Byrnes, Christian T.; Lewis, Antony

    2016-08-01

    Negative absolute temperatures (NAT) are an exotic thermodynamical consequence of quantum physics which has been known since the 1950's (having been achieved in the lab on a number of occasions). Recently, the work of Braun et al. [1] has rekindled interest in negative temperatures and hinted at a possibility of using NAT systems in the lab as dark energy analogues. This paper goes one step further, looking into the cosmological consequences of the existence of a NAT component in the Universe. NAT-dominated expanding Universes experience a borderline phantom expansion (w < -1) with no Big Rip, and their contracting counterparts are forced to bounce after the energy density becomes sufficiently large. Both scenarios might be used to solve horizon and flatness problems analogously to standard inflation and bouncing cosmologies. We discuss the difficulties in obtaining and ending a NAT-dominated epoch, and possible ways of obtaining density perturbations with an acceptable spectrum.

  4. The photon

    NASA Astrophysics Data System (ADS)

    Collins, Russell L.

    2009-10-01

    There are no TEM waves, only photons. Lets build a photon, using a radio antenna. A short antenna (2L<< λ) simplifies the calculation, letting B fall off everywhere as 1/r^2. The Biot-Savart law finds B = (μ0/4π)(LI0/r^2)θφt. The magnetic flux thru a semi-circle of radius λ/2 is set equal to the flux quantum h/e, determining the needed source strength, LI0. From this, one can integrate the magnetic energy density over a sphere of radius λ/2 and finds it to be 1.0121 hc/λ. Pretty close. A B field collapses when the current ceases, but the photon evades this by creating a ɛ0E / t displacement current at center that fully supports the toroidal B assembly as it moves at c. This E=vxB arises because the photon moves at c. Stopped, a photon decays. At every point along the photon's path, an observer will note a transient oscillation of an E field. This sources the EM ``guiding wave'', carrying little or no energy and expanding at c. At the head of the photon, all these spherical guiding waves gather ``in-phase'' as a planar wavefront. This model speaks to all the many things we know about light. The photon is tiny, but its guiding wave is huge.

  5. Sounding rocket measurement of the absolute solar EUV flux utilizing a silicon photodiode

    NASA Technical Reports Server (NTRS)

    Ogawa, H. S.; Mcmullin, D.; Judge, D. L.; Canfield, L. R.

    1990-01-01

    A newly developed stable and high quantum efficiency silicon photodiode was used to obtain an accurate measurement of the integrated absolute magnitude of the solar extreme UV photon flux in the spectral region between 50 and 800 A. The adjusted daily 10.7-cm solar radio flux and sunspot number were 168.4 and 121, respectively. The unattenuated absolute value of the solar EUV flux at 1 AU in the specified wavelength region was 6.81 x 10 to the 10th photons/sq cm per s. Based on a nominal probable error of 7 percent for National Institute of Standards and Technology detector efficiency measurements in the 50- to 500-A region (5 percent on longer wavelength measurements between 500 and 1216 A), and based on experimental errors associated with the present rocket instrumentation and analysis, a conservative total error estimate of about 14 percent is assigned to the absolute integral solar flux obtained.

  6. Determination of absolute internal conversion coefficients using the SAGE spectrometer

    NASA Astrophysics Data System (ADS)

    Sorri, J.; Greenlees, P. T.; Papadakis, P.; Konki, J.; Cox, D. M.; Auranen, K.; Partanen, J.; Sandzelius, M.; Pakarinen, J.; Rahkila, P.; Uusitalo, J.; Herzberg, R.-D.; Smallcombe, J.; Davies, P. J.; Barton, C. J.; Jenkins, D. G.

    2016-03-01

    A non-reference based method to determine internal conversion coefficients using the SAGE spectrometer is carried out for transitions in the nuclei of 154Sm, 152Sm and 166Yb. The Normalised-Peak-to-Gamma method is in general an efficient tool to extract internal conversion coefficients. However, in many cases the required well-known reference transitions are not available. The data analysis steps required to determine absolute internal conversion coefficients with the SAGE spectrometer are presented. In addition, several background suppression methods are introduced and an example of how ancillary detectors can be used to select specific reaction products is given. The results obtained for ground-state band E2 transitions show that the absolute internal conversion coefficients can be extracted using the methods described with a reasonable accuracy. In some cases of less intense transitions only an upper limit for the internal conversion coefficient could be given.

  7. Absolute Measurements of Radiation Damage in Nanometer Thick Films

    PubMed Central

    Alizadeh, Elahe; Sanche, Léon

    2013-01-01

    We address the problem of absolute measurements of radiation damage in films of nanometer thicknesses. Thin films of DNA (~ 2–160nm) are deposited onto glass substrates and irradiated with varying doses of 1.5 keV X-rays under dry N2 at atmospheric pressure and room temperature. For each different thickness, the damage is assessed by measuring the loss of the supercoiled configuration as a function of incident photon fluence. From the exposure curves, the G-values are deduced, assuming that X-ray photons interacting with DNA, deposit all of their energy in the film. The results show that the G-value (i.e., damage per unit of deposited energy) increases with film thickness and reaches a plateau at 30±5 nm. This thickness dependence provides a correction factor to estimate the actual G-value for films with thicknesses below 30nm thickness. Thus, the absolute values of damage can be compared with that of films of any thickness under different experimental conditions. PMID:22562941

  8. Two-Photon Excitation of trans-Stilbene: Spectroscopy and Dynamics of Electronically Excited States above S1.

    PubMed

    Houk, Amanda L; Zheldakov, Igor L; Tommey, Tyler A; Elles, Christopher G

    2015-07-23

    The photoisomerization dynamics of trans-stilbene have been well studied in the lowest excited state, but much less is known about the behavior following excitation to higher-lying electronically excited states. This contribution reports a combined study of the spectroscopy and dynamics of two-photon accessible states above S1. Two-photon absorption (2PA) measurements using a broadband pump-probe technique reveal distinct bands near 5.1 and 6.4 eV. The 2PA bands have absolute cross sections of 40 ± 16 and 270 ± 110 GM, respectively, and a pump-probe polarization dependence that suggests both of the transitions access Ag-symmetry excited states. Separate transient absorption measurements probe the excited-state dynamics following two-photon excitation into each of the bands using intense pulses of 475 and 380 nm light, respectively. The initially excited states rapidly relax via internal conversion, leading to the formation of an S1 excited-state absorption band that is centered near 585 nm and evolves on a time scale of 1-2 ps due to intramolecular vibrational relaxation. The subsequent evolution of the S1 excited-state absorption is identical to the behavior following direct one-photon excitation of the lowest excited state at 4.0 eV. The complementary spectroscopy and dynamics measurements provide new benchmarks for computational studies of the electronic structure and dynamics of this model system on excited states above S1. Probing the dynamics of molecules in their higher-lying excited states is an important frontier in chemical reaction dynamics.

  9. Absolute configuration of isovouacapenol C

    PubMed Central

    Fun, Hoong-Kun; Yodsaoue, Orapun; Karalai, Chatchanok; Chantrapromma, Suchada

    2010-01-01

    The title compound, C27H34O5 {systematic name: (4aR,5R,6R,6aS,7R,11aS,11bR)-4a,6-dihy­droxy-4,4,7,11b-tetra­methyl-1,2,3,4,4a,5,6,6a,7,11,11a,11b-dodeca­hydro­phenanthro[3,2-b]furan-5-yl benzoate}, is a cassane furan­oditerpene, which was isolated from the roots of Caesalpinia pulcherrima. The three cyclo­hexane rings are trans fused: two of these are in chair conformations with the third in a twisted half-chair conformation, whereas the furan ring is almost planar (r.m.s. deviation = 0.003 Å). An intra­molecular C—H⋯O inter­action generates an S(6) ring. The absolute configurations of the stereogenic centres at positions 4a, 5, 6, 6a, 7, 11a and 11b are R, R, R, S, R, S and R, respectively. In the crystal, mol­ecules are linked into infinite chains along [010] by O—H⋯O hydrogen bonds. C⋯O [3.306 (2)–3.347 (2) Å] short contacts and C—H⋯π inter­actions also occur. PMID:21588364

  10. Novel photonic crystal cavities and related structures.

    SciTech Connect

    Luk, Ting Shan

    2007-11-01

    The key accomplishment of this project is to achieve a much more in-depth understanding of the thermal emission physics of metallic photonic crystal through theoretical modeling and experimental measurements. An improved transfer matrix technique was developed to enable incorporation of complex dielectric function. Together with microscopic theory describing emitter radiative and non-radiative relaxation dynamics, a non-equilibrium thermal emission model is developed. Finally, experimental methodology was developed to measure absolute emissivity of photonic crystal at high temperatures with accuracy of +/-2%. Accurate emissivity measurements allow us to validate the procedure to treat the effect of the photonic crystal substrate.

  11. Measurement of the absolute and differential cross sections for 7Li(γ, n0)6Li

    SciTech Connect

    W.A. Wurtz, R.E. Pywell, B.E. Norum, S. Kucuker, B.D. Sawatzky, H.R. Weller, M.W. Ahmed, S. Stave

    2011-10-01

    We have measured the cross section of the photoneutron reaction channel {sup 7}Li+{gamma}{yields}{sup 6}Li(g.s.)+n where the progeny nucleus is the ground state of {sup 6}Li. We obtained the absolute cross section at photon energies 10, 11, 12, 13, 15, 20, 25, 30, and 35 MeV and also the dependence of the cross section on polar angle for all but the highest photon energy. For the energies 10 to 15 MeV we were able to use linearly polarized photons to obtain the dependence of the cross section on the photon polarization.

  12. Frequency-domain analysis of absolute gravimeters

    NASA Astrophysics Data System (ADS)

    Svitlov, S.

    2012-12-01

    An absolute gravimeter is analysed as a linear time-invariant system in the frequency domain. Frequency responses of absolute gravimeters are derived analytically based on the propagation of the complex exponential signal through their linear measurement functions. Depending on the model of motion and the number of time-distance coordinates, an absolute gravimeter is considered as a second-order (three-level scheme) or third-order (multiple-level scheme) low-pass filter. It is shown that the behaviour of an atom absolute gravimeter in the frequency domain corresponds to that of the three-level corner-cube absolute gravimeter. Theoretical results are applied for evaluation of random and systematic measurement errors and optimization of an experiment. The developed theory agrees with known results of an absolute gravimeter analysis in the time and frequency domains and can be used for measurement uncertainty analyses, building of vibration-isolation systems and synthesis of digital filtering algorithms.

  13. Photon generator

    DOEpatents

    Srinivasan-Rao, Triveni

    2002-01-01

    A photon generator includes an electron gun for emitting an electron beam, a laser for emitting a laser beam, and an interaction ring wherein the laser beam repetitively collides with the electron beam for emitting a high energy photon beam therefrom in the exemplary form of x-rays. The interaction ring is a closed loop, sized and configured for circulating the electron beam with a period substantially equal to the period of the laser beam pulses for effecting repetitive collisions.

  14. Nonlocal hyperconcentration on entangled photons using photonic module system

    NASA Astrophysics Data System (ADS)

    Cao, Cong; Wang, Tie-Jun; Mi, Si-Chen; Zhang, Ru; Wang, Chuan

    2016-06-01

    Entanglement distribution will inevitably be affected by the channel and environment noise. Thus distillation of maximal entanglement nonlocally becomes a crucial goal in quantum information. Here we illustrate that maximal hyperentanglement on nonlocal photons could be distilled using the photonic module and cavity quantum electrodynamics, where the photons are simultaneously entangled in polarization and spatial-mode degrees of freedom. The construction of the photonic module in a photonic band-gap structure is presented, and the operation of the module is utilized to implement the photonic nondestructive parity checks on the two degrees of freedom. We first propose a hyperconcentration protocol using two identical partially hyperentangled initial states with unknown coefficients to distill a maximally hyperentangled state probabilistically, and further propose a protocol by the assistance of an ancillary single photon prepared according to the known coefficients of the initial state. In the two protocols, the total success probability can be improved greatly by introducing the iteration mechanism, and only one of the remote parties is required to perform the parity checks in each round of iteration. Estimates on the system requirements and recent experimental results indicate that our proposal is realizable with existing or near-further technologies.

  15. Photonic lanterns

    NASA Astrophysics Data System (ADS)

    Leon-Saval, Sergio G.; Argyros, Alexander; Bland-Hawthorn, Joss

    2013-12-01

    Multimode optical fibers have been primarily (and almost solely) used as "light pipes" in short distance telecommunications and in remote and astronomical spectroscopy. The modal properties of the multimode waveguides are rarely exploited and mostly discussed in the context of guiding light. Until recently, most photonic applications in the applied sciences have arisen from developments in telecommunications. However, the photonic lantern is one of several devices that arose to solve problems in astrophotonics and space photonics. Interestingly, these devices are now being explored for use in telecommunications and are likely to find commercial use in the next few years, particularly in the development of compact spectrographs. Photonic lanterns allow for a low-loss transformation of a multimode waveguide into a discrete number of single-mode waveguides and vice versa, thus enabling the use of single-mode photonic technologies in multimode systems. In this review, we will discuss the theory and function of the photonic lantern, along with several different variants of the technology. We will also discuss some of its applications in more detail. Furthermore, we foreshadow future applications of this technology to the field of nanophotonics.

  16. Production of photocurrent due to intermediate-to-conduction-band transitions: a demonstration of a key operating principle of the intermediate-band solar cell.

    PubMed

    Martí, A; Antolín, E; Stanley, C R; Farmer, C D; López, N; Díaz, P; Cánovas, E; Linares, P G; Luque, A

    2006-12-15

    We present intermediate-band solar cells manufactured using quantum dot technology that show for the first time the production of photocurrent when two sub-band-gap energy photons are absorbed simultaneously. One photon produces an optical transition from the intermediate-band to the conduction band while the second pumps an electron from the valence band to the intermediate-band. The detection of this two-photon absorption process is essential to verify the principles of operation of the intermediate-band solar cell. The phenomenon is the cornerstone physical principle that ultimately allows the production of photocurrent in a solar cell by below band gap photon absorption, without degradation of its output voltage. PMID:17280325

  17. A novel method for measurement of concentration using two dimensional photonic crystal structures

    NASA Astrophysics Data System (ADS)

    Palai, Gopinath; Tripathy, Sukanta Kumar

    2012-05-01

    A novel method to measure the concentration of sugar, sodium chloride and alcohol, in their aqueous solution by using two dimensional photonic crystal structures is presented. This measurement is very accurate as the principle is based on variation of photonic band gap with respect to concentration. Photonic band gap here is computed using plane wave expansion method.

  18. Chiral isothiocyanates - An approach to determination of the absolute configuration using circular dichroism measurement

    NASA Astrophysics Data System (ADS)

    Michalski, Oskar; Cież, Dariusz

    2013-04-01

    Chiral alkyl 2-isothiocyanates have been obtained from enantiopure, aliphatic amines. ECD measurements allowed us to correlate an absolute configuration at C-2 with a sign of the Cotton effect (CE) observed for n-π* transition at the longer-wavelength range of the spectrum. Chirooptical data calculated for all enantiomers were consistent with the measured CE values and indicated that the weak absorption band at 240 nm could give an important information concerning the stereochemistry of simple, chiral isothiocyanates. Optically active esters of 2-isothiocyanatocarboxylic acids, prepared from α-amino acids, showed two absorption bands located over 195 nm. The more intensive band near 200 nm and the weak absorption located at 250 nm were related to n-π* transitions in NCS group. TD DFT calculations carried out for methyl esters of 2-isothiocyanatocarboxylic acids showed the correlation between signs of CE determined for both absorption bands, and the absolute configuration on C-2.

  19. Laparoscopic gastric banding

    MedlinePlus

    ... adjustable gastric banding; Bariatric surgery - laparoscopic gastric banding; Obesity - gastric banding; Weight loss - gastric banding ... gastric banding is not a "quick fix" for obesity. It will greatly change your lifestyle. You must ...

  20. Absolute Income, Relative Income, and Happiness

    ERIC Educational Resources Information Center

    Ball, Richard; Chernova, Kateryna

    2008-01-01

    This paper uses data from the World Values Survey to investigate how an individual's self-reported happiness is related to (i) the level of her income in absolute terms, and (ii) the level of her income relative to other people in her country. The main findings are that (i) both absolute and relative income are positively and significantly…

  1. Investigating Absolute Value: A Real World Application

    ERIC Educational Resources Information Center

    Kidd, Margaret; Pagni, David

    2009-01-01

    Making connections between various representations is important in mathematics. In this article, the authors discuss the numeric, algebraic, and graphical representations of sums of absolute values of linear functions. The initial explanations are accessible to all students who have experience graphing and who understand that absolute value simply…

  2. Preschoolers' Success at Coding Absolute Size Values.

    ERIC Educational Resources Information Center

    Russell, James

    1980-01-01

    Forty-five 2-year-old and forty-five 3-year-old children coded relative and absolute sizes using 1.5-inch, 6-inch, and 18-inch cardboard squares. Results indicate that absolute coding is possible for children of this age. (Author/RH)

  3. Introducing the Mean Absolute Deviation "Effect" Size

    ERIC Educational Resources Information Center

    Gorard, Stephen

    2015-01-01

    This paper revisits the use of effect sizes in the analysis of experimental and similar results, and reminds readers of the relative advantages of the mean absolute deviation as a measure of variation, as opposed to the more complex standard deviation. The mean absolute deviation is easier to use and understand, and more tolerant of extreme…

  4. Estimating the absolute wealth of households

    PubMed Central

    Gerkey, Drew; Hadley, Craig

    2015-01-01

    Abstract Objective To estimate the absolute wealth of households using data from demographic and health surveys. Methods We developed a new metric, the absolute wealth estimate, based on the rank of each surveyed household according to its material assets and the assumed shape of the distribution of wealth among surveyed households. Using data from 156 demographic and health surveys in 66 countries, we calculated absolute wealth estimates for households. We validated the method by comparing the proportion of households defined as poor using our estimates with published World Bank poverty headcounts. We also compared the accuracy of absolute versus relative wealth estimates for the prediction of anthropometric measures. Findings The median absolute wealth estimates of 1 403 186 households were 2056 international dollars per capita (interquartile range: 723–6103). The proportion of poor households based on absolute wealth estimates were strongly correlated with World Bank estimates of populations living on less than 2.00 United States dollars per capita per day (R2 = 0.84). Absolute wealth estimates were better predictors of anthropometric measures than relative wealth indexes. Conclusion Absolute wealth estimates provide new opportunities for comparative research to assess the effects of economic resources on health and human capital, as well as the long-term health consequences of economic change and inequality. PMID:26170506

  5. Absolute optical metrology : nanometers to kilometers

    NASA Technical Reports Server (NTRS)

    Dubovitsky, Serge; Lay, O. P.; Peters, R. D.; Liebe, C. C.

    2005-01-01

    We provide and overview of the developments in the field of high-accuracy absolute optical metrology with emphasis on space-based applications. Specific work on the Modulation Sideband Technology for Absolute Ranging (MSTAR) sensor is described along with novel applications of the sensor.

  6. Passive polarization rotator based on silica photonic crystal fiber for 1.31-μm and 1.55-μm bands via adjusting the fiber length

    NASA Astrophysics Data System (ADS)

    Chen, Lei; Zhang, Wei-Gang; Wang, Li; Bai, Zhi-Yong; Zhang, Shan-Shan; Wang, Biao; Yan, Tie-Yi; Jonathan, Sieg

    2014-10-01

    A new polarization rotator based on the silica photonic crystal fiber is proposed. The proposed polarization rotator photonic crystal fiber (PR-PCF) possesses a triangle jigsaw-shape core region. The full-vector finite-element method is used to analyze the phenomenon of polarization conversion between the quasi-TE and quasi-TM modes. Numerical simulations show that the wavelengths of 1.31 μm and 1.55 μm are converted with a nearly 100% polarization conversion ratio with their matched coupling length and has a relatively strong realistic fabrication tolerance -100 nm on the y axis and 50 nm on the x axis. The full vectorial finite difference beam propagation method is used to confirm the performance of the proposed PR-PCF.

  7. Absolute instability of the Gaussian wake profile

    NASA Technical Reports Server (NTRS)

    Hultgren, Lennart S.; Aggarwal, Arun K.

    1987-01-01

    Linear parallel-flow stability theory has been used to investigate the effect of viscosity on the local absolute instability of a family of wake profiles with a Gaussian velocity distribution. The type of local instability, i.e., convective or absolute, is determined by the location of a branch-point singularity with zero group velocity of the complex dispersion relation for the instability waves. The effects of viscosity were found to be weak for values of the wake Reynolds number, based on the center-line velocity defect and the wake half-width, larger than about 400. Absolute instability occurs only for sufficiently large values of the center-line wake defect. The critical value of this parameter increases with decreasing wake Reynolds number, thereby indicating a shrinking region of absolute instability with decreasing wake Reynolds number. If backflow is not allowed, absolute instability does not occur for wake Reynolds numbers smaller than about 38.

  8. Quantum Logic with Cavity Photons From Single Atoms.

    PubMed

    Holleczek, Annemarie; Barter, Oliver; Rubenok, Allison; Dilley, Jerome; Nisbet-Jones, Peter B R; Langfahl-Klabes, Gunnar; Marshall, Graham D; Sparrow, Chris; O'Brien, Jeremy L; Poulios, Konstantinos; Kuhn, Axel; Matthews, Jonathan C F

    2016-07-01

    We demonstrate quantum logic using narrow linewidth photons that are produced with an a priori nonprobabilistic scheme from a single ^{87}Rb atom strongly coupled to a high-finesse cavity. We use a controlled-not gate integrated into a photonic chip to entangle these photons, and we observe nonclassical correlations between photon detection events separated by periods exceeding the travel time across the chip by 3 orders of magnitude. This enables quantum technology that will use the properties of both narrow-band single photon sources and integrated quantum photonics.

  9. Quantum Logic with Cavity Photons From Single Atoms.

    PubMed

    Holleczek, Annemarie; Barter, Oliver; Rubenok, Allison; Dilley, Jerome; Nisbet-Jones, Peter B R; Langfahl-Klabes, Gunnar; Marshall, Graham D; Sparrow, Chris; O'Brien, Jeremy L; Poulios, Konstantinos; Kuhn, Axel; Matthews, Jonathan C F

    2016-07-01

    We demonstrate quantum logic using narrow linewidth photons that are produced with an a priori nonprobabilistic scheme from a single ^{87}Rb atom strongly coupled to a high-finesse cavity. We use a controlled-not gate integrated into a photonic chip to entangle these photons, and we observe nonclassical correlations between photon detection events separated by periods exceeding the travel time across the chip by 3 orders of magnitude. This enables quantum technology that will use the properties of both narrow-band single photon sources and integrated quantum photonics. PMID:27447506

  10. Quantum Logic with Cavity Photons From Single Atoms

    NASA Astrophysics Data System (ADS)

    Holleczek, Annemarie; Barter, Oliver; Rubenok, Allison; Dilley, Jerome; Nisbet-Jones, Peter B. R.; Langfahl-Klabes, Gunnar; Marshall, Graham D.; Sparrow, Chris; O'Brien, Jeremy L.; Poulios, Konstantinos; Kuhn, Axel; Matthews, Jonathan C. F.

    2016-07-01

    We demonstrate quantum logic using narrow linewidth photons that are produced with an a priori nonprobabilistic scheme from a single 87Rb atom strongly coupled to a high-finesse cavity. We use a controlled-not gate integrated into a photonic chip to entangle these photons, and we observe nonclassical correlations between photon detection events separated by periods exceeding the travel time across the chip by 3 orders of magnitude. This enables quantum technology that will use the properties of both narrow-band single photon sources and integrated quantum photonics.

  11. Dynamic frequency-domain interferometer for absolute distance measurements with high resolution

    SciTech Connect

    Weng, Jidong; Liu, Shenggang; Ma, Heli; Tao, Tianjiong; Wang, Xiang; Liu, Cangli; Tan, Hua

    2014-11-15

    A unique dynamic frequency-domain interferometer for absolute distance measurement has been developed recently. This paper presents the working principle of the new interferometric system, which uses a photonic crystal fiber to transmit the wide-spectrum light beams and a high-speed streak camera or frame camera to record the interference stripes. Preliminary measurements of harmonic vibrations of a speaker, driven by a radio, and the changes in the tip clearance of a rotating gear wheel show that this new type of interferometer has the ability to perform absolute distance measurements both with high time- and distance-resolution.

  12. Vesicle Photonics

    SciTech Connect

    Vasdekis, Andreas E.; Scott, E. A.; Roke, Sylvie; Hubbell, J. A.; Psaltis, D.

    2013-04-03

    Thin membranes, under appropriate boundary conditions, can self-assemble into vesicles, nanoscale bubbles that encapsulate and hence protect or transport molecular payloads. In this paper, we review the types and applications of light fields interacting with vesicles. By encapsulating light-emitting molecules (e.g. dyes, fluorescent proteins, or quantum dots), vesicles can act as particles and imaging agents. Vesicle imaging can take place also under second harmonic generation from vesicle membrane, as well as employing mass spectrometry. Light fields can also be employed to transport vesicles using optical tweezers (photon momentum) or directly pertrurbe the stability of vesicles and hence trigger the delivery of the encapsulated payload (photon energy).

  13. Photons Revisited

    NASA Astrophysics Data System (ADS)

    Batic, Matej; Begalli, Marcia; Han, Min Cheol; Hauf, Steffen; Hoff, Gabriela; Kim, Chan Hyeong; Kim, Han Sung; Grazia Pia, Maria; Saracco, Paolo; Weidenspointner, Georg

    2014-06-01

    A systematic review of methods and data for the Monte Carlo simulation of photon interactions is in progress: it concerns a wide set of theoretical modeling approaches and data libraries available for this purpose. Models and data libraries are assessed quantitatively with respect to an extensive collection of experimental measurements documented in the literature to determine their accuracy; this evaluation exploits rigorous statistical analysis methods. The computational performance of the associated modeling algorithms is evaluated as well. An overview of the assessment of photon interaction models and results of the experimental validation are presented.

  14. Green photonics

    NASA Astrophysics Data System (ADS)

    Quan, Frederic

    2012-02-01

    Photonics, the broad merger of electronics with the optical sciences, encompasses such a wide swath of technology that its impact is almost universal in our everyday lives. This is a broad overview of some aspects of the industry and their contribution to the ‘green’ or environmental movement. The rationale for energy conservation is briefly discussed and the impact of photonics on our everyday lives and certain industries is described. Some opinions from industry are presented along with market estimates. References are provided to some of the most recent research in these areas.

  15. Frequency-bin entangled photons

    SciTech Connect

    Olislager, L.; Emplit, P.; Nguyen, A. T.; Massar, S.; Merolla, J.-M.; Huy, K. Phan

    2010-07-15

    A monochromatic laser pumping a parametric down-conversion crystal generates frequency-entangled photon pairs. We study this experimentally by addressing such frequency-entangled photons at telecommunication wavelengths (around 1550 nm) with fiber-optics components such as electro-optic phase modulators and narrow-band frequency filters. The theory underlying our approach uses the notion of frequency-bin entanglement. Our results show that the phase modulators address coherently up to eleven frequency bins, leading to an interference pattern which can violate by more than five standard deviations a Bell inequality adapted to our setup.

  16. STANDARDIZING TYPE Ia SUPERNOVA ABSOLUTE MAGNITUDES USING GAUSSIAN PROCESS DATA REGRESSION

    SciTech Connect

    Kim, A. G.; Aldering, G.; Aragon, C.; Bailey, S.; Childress, M.; Fakhouri, H. K.; Nordin, J.; Thomas, R. C.; Antilogus, P.; Bongard, S.; Canto, A.; Cellier-Holzem, F.; Guy, J.; Baltay, C.; Buton, C.; Kerschhaggl, M.; Kowalski, M.; Chotard, N.; Copin, Y.; Gangler, E.; and others

    2013-04-01

    We present a novel class of models for Type Ia supernova time-evolving spectral energy distributions (SEDs) and absolute magnitudes: they are each modeled as stochastic functions described by Gaussian processes. The values of the SED and absolute magnitudes are defined through well-defined regression prescriptions, so that data directly inform the models. As a proof of concept, we implement a model for synthetic photometry built from the spectrophotometric time series from the Nearby Supernova Factory. Absolute magnitudes at peak B brightness are calibrated to 0.13 mag in the g band and to as low as 0.09 mag in the z = 0.25 blueshifted i band, where the dispersion includes contributions from measurement uncertainties and peculiar velocities. The methodology can be applied to spectrophotometric time series of supernovae that span a range of redshifts to simultaneously standardize supernovae together with fitting cosmological parameters.

  17. A simple perturbative tool to calculate plasmonic photonic bandstructures

    NASA Astrophysics Data System (ADS)

    Mohammed, Faris; Quandt, Alexander

    2016-06-01

    We use first order perturbation theory to study the effect of surface plasmon polaritons on the photonic band structure of plasmonic photonic crystals. Our results are based on a simple numerical tool that we have developed to extend the standard frequency domain methods to compute the photonic band structure of plasmonic photonic crystals. For a two-dimensional honeycomb photonic crystal with a lattice constant of 500 nm placed on an aluminium substrate, we show that the band gap for TM modes is enhanced by 13%. Thus a slight variation in the effective dielectric function results in a plasmonic band structure that is not scale-invariant, which is reminiscent of the inherent non-linear properties of the effective dielectric constant.

  18. Strongly-Refractive One-Dimensional Photonic Crystal Prisms

    NASA Technical Reports Server (NTRS)

    Ting, David Z. (Inventor)

    2004-01-01

    One-dimensional (1D) photonic crystal prisms can separate a beam of polychromatic electromagnetic waves into constituent wavelength components and can utilize unconventional refraction properties for wavelength dispersion over significant portions of an entire photonic band rather than just near the band edges outside the photonic band gaps. Using a ID photonic crystal simplifies the design and fabrication process and allows the use of larger feature sizes. The prism geometry broadens the useful wavelength range, enables better optical transmission, and exhibits angular dependence on wavelength with reduced non-linearity. The properties of the 1 D photonic crystal prism can be tuned by varying design parameters such as incidence angle, exit surface angle, and layer widths. The ID photonic crystal prism can be fabricated in a planar process, and can be used as optical integrated circuit elements.

  19. Topological Photonic States

    NASA Astrophysics Data System (ADS)

    He, Cheng; Lin, Liang; Sun, Xiao-Chen; Liu, Xiao-Ping; Lu, Ming-Hui; Chen, Yan-Feng

    2014-01-01

    As exotic phenomena in optics, topological states in photonic crystals have drawn much attention due to their fundamental significance and great potential applications. Because of the broken time-reversal symmetry under the influence of an external magnetic field, the photonic crystals composed of magneto-optical materials will lead to the degeneracy lifting and show particular topological characters of energy bands. The upper and lower bulk bands have nonzero integer topological numbers. The gapless edge states can be realized to connect two bulk states. This topological photonic states originated from the topological property can be analogous to the integer quantum Hall effect in an electronic system. The gapless edge state only possesses a single sign of gradient in the whole Brillouin zone, and thus the group velocity is only in one direction leading to the one-way energy flow, which is robust to disorder and impurity due to the nontrivial topological nature of the corresponding electromagnetic states. Furthermore, this one-way edge state would cross the Brillouin center with nonzero group velocity, where the negative-zero-positive phase velocity can be used to realize some interesting phenomena such as tunneling and backward phase propagation. On the other hand, under the protection of time-reversal symmetry, a pair of gapless edge states can also be constructed by using magnetic-electric coupling meta-materials, exhibiting Fermion-like spin helix topological edge states, which can be regarded as an optical counterpart of topological insulator originating from the spin-orbit coupling. The aim of this article is to have a comprehensive review of recent research literatures published in this emerging field of photonic topological phenomena. Photonic topological states and their related phenomena are presented and analyzed, including the chiral edge states, polarization dependent transportation, unidirectional waveguide and nonreciprocal optical transmission, all

  20. Cross sections and band strengths for the N2O/+/ /A 2Sigma+ to X 2Pi/ system produced by vacuum ultraviolet radiation

    NASA Technical Reports Server (NTRS)

    Lee, L. C.; Judge, D. L.

    1974-01-01

    Analysis of cross sections that have been obtained for the production of the N2O(+) (A 2Sigma+ to X 2Pi) fluorescence, using vacuum ultraviolet radiation between 462 and 755 A. The fluorescence spectra produced using incident photons of 715.6- and 754.9-A wavelengths are presented, as well as the relative fluorescence cross sections for the individual observed bands of the above-mentioned N2O(+) system. Finally, absolute cross sections for the production of the N2O(+) (A 2Sigma+ to X 2Pi) system are presented, as well as band strengths for the A 2Sigma+(0,0,0) to X 2Pi(n1,n2,0) fluorescence.

  1. Absolute doubly differential bremsstrahlung cross sections from rare gas atoms

    NASA Astrophysics Data System (ADS)

    Portillo, Salvador

    The absolute doubly differential bremsstrahlung cross section has been measured for 28 and 50 keV electrons incident on the rare gases Xe, Kr, Ar and Ne. The cross sections are differential with respect to energy and photon emission. A SiLi solid state detector measured data at 90° with respect to the beam line. A thorough analysis of the experimental systematic error yielded a high degree of confidence in the experimental data. The absolute bremsstrahlung doubly differential cross sections provided for a rigorous test of the normal bremsstrahlung theory, tabulated by Kissel, Quarles and Pratt1 (KQP) and of the SA theory2 that includes the contribution from polarization bremsstrahlung. To test the theories a comparison of the overall magnitude of the cross section as well as comparison of the photon energy dependence was carried out. The KQP theoretical values underestimated the magnitude of the cross section for all targets and for both energies. The SA values were in excellent agreement with the 28 keV data. For the 50keV data the fit was also very good. However, there were energy regions where there was a small discrepancy between the theory and the data. This suggests that the Polarization Bremsstrahlung (PB) mechanism does contribute to the overall spectrum and is detectable in this parameter space. 1Kissel, L., Quarles, C. A., Pratt, R. H., Atom. Data Nucl. Data Tables 28, 381 (1983). 2Avdonina N. B., Pratt, R. H., J. Phys. B: At. Mol. Opt. Phys. 32 4261 (1999).

  2. Mechanically tunable photonic crystal lens

    NASA Astrophysics Data System (ADS)

    Cui, Y.; Tamma, V. A.; Lee, J.-B.; Park, W.

    2010-08-01

    We designed, fabricated and characterized MEMS-enabled mechanically-tunable photonic crystal lens comprised of 2D photonic crystal and symmetrical electro-thermal actuators. The 2D photonic crystal was made of a honeycomb-lattice of 340 nm thick, 260 nm diameter high-index silicon rods embedded in low-index 10 μm thick SU-8 cladding. Silicon input waveguide and deflection block were also fabricated for light in-coupling and monitoring of focused spot size, respectively. When actuated, the electro-thermal actuators induced mechanical strain which changed the lattice constant of the photonic crystal and consequently modified the photonic band structure. This in turn modified the focal-length of the photonic crystal lens. The fabricated device was characterized using a tunable laser (1400~1602 nm) and an infrared camera during actuation. At the wavelength of 1450 nm, the lateral light spot size observed at the deflection block gradually decreased 40%, as applied current increased from 0 to 0.7 A, indicating changes in focal length in response to the mechanical stretching.

  3. The 2ν{sub 3} Raman overtone of sulfur hexafluoride: Absolute spectra, pressure effects, and polarizability properties

    SciTech Connect

    Chrysos, M. Rachet, F.; Kremer, D.

    2014-03-28

    Of the six normal vibrations of SF{sub 6}, ν{sub 3} has a key role in the mechanisms of radiative forcing. This vibration, though inactive in Raman, shows up through the transition 2ν{sub 3} allowing for a complementary view on the asymmetric stretch of the molecule. Here, we look back into this topic, which has already caught some interest in the past but with some points been left out. We make a systematic incoherent-light-scattering analysis of the overtone with the use of different gas pressures and polarization orientations for the incident beam. Absolute-scale isotropic and anisotropic spectra are reported along with natural and pressure-induced widths and shifts, and other spectral features such as the peaks corresponding to the (experimentally indistinguishable) interfering channels E{sub g} and F{sub 2g} hitherto seen solely as two-photon IR-absorption features. We make the first-ever prediction of the SF{sub 6} polarizability second derivative with respect to the ν{sub 3}-mode coordinate and we develop a heuristic argument to explain why the superposition of the three degenerate stretching motions that are related to the ν{sub 3} mode cannot but generate a polarized Raman band.

  4. Photon-photon collisions via relativisitic mirrors

    SciTech Connect

    Koga, James K.

    2012-07-11

    Photon-photon scattering at low energies has been predicted theoretically for many years. However, due to the extremely small cross section there has been no experimental confirmation of this. Due to the rapid increase in laser irradiances and projected peak irradiances in planned facilities regimes could be reached where photon-photon scattering could be experimentally observed. We will first review basic aspects of photon-photon collisions concentrating on the calculation of the photon-photon scattering cross section. Then we will discuss the possibilities for observing these phenomena in ultra-high irradiance laser-plasma interactions involving relativistic mirrors.

  5. Absolute magnitudes of trans-neptunian objects

    NASA Astrophysics Data System (ADS)

    Duffard, R.; Alvarez-candal, A.; Pinilla-Alonso, N.; Ortiz, J. L.; Morales, N.; Santos-Sanz, P.; Thirouin, A.

    2015-10-01

    Accurate measurements of diameters of trans- Neptunian objects are extremely complicated to obtain. Radiomatric techniques applied to thermal measurements can provide good results, but precise absolute magnitudes are needed to constrain diameters and albedos. Our objective is to measure accurate absolute magnitudes for a sample of trans- Neptunian objects, many of which have been observed, and modelled, by the "TNOs are cool" team, one of Herschel Space Observatory key projects grantes with ~ 400 hours of observing time. We observed 56 objects in filters V and R, if possible. These data, along with data available in the literature, was used to obtain phase curves and to measure absolute magnitudes by assuming a linear trend of the phase curves and considering magnitude variability due to rotational light-curve. In total we obtained 234 new magnitudes for the 56 objects, 6 of them with no reported previous measurements. Including the data from the literature we report a total of 109 absolute magnitudes.

  6. A New Gimmick for Assigning Absolute Configuration.

    ERIC Educational Resources Information Center

    Ayorinde, F. O.

    1983-01-01

    A five-step procedure is provided to help students in making the assignment absolute configuration less bothersome. Examples for both single (2-butanol) and multi-chiral carbon (3-chloro-2-butanol) molecules are included. (JN)

  7. The Simplicity Argument and Absolute Morality

    ERIC Educational Resources Information Center

    Mijuskovic, Ben

    1975-01-01

    In this paper the author has maintained that there is a similarity of thought to be found in the writings of Cudworth, Emerson, and Husserl in his investigation of an absolute system of morality. (Author/RK)

  8. Photon Collider Physics with Real Photon Beams

    SciTech Connect

    Gronberg, J; Asztalos, S

    2005-11-03

    Photon-photon interactions have been an important probe into fundamental particle physics. Until recently, the only way to produce photon-photon collisions was parasitically in the collision of charged particles. Recent advances in short-pulse laser technology have made it possible to consider producing high intensity, tightly focused beams of real photons through Compton scattering. A linear e{sup +}e{sup -} collider could thus be transformed into a photon-photon collider with the addition of high power lasers. In this paper they show that it is possible to make a competitive photon-photon collider experiment using the currently mothballed Stanford Linear Collider. This would produce photon-photon collisions in the GeV energy range which would allow the discovery and study of exotic heavy mesons with spin states of zero and two.

  9. Intermediate Band Solar Cell with Extreme Broadband Spectrum Quantum Efficiency

    NASA Astrophysics Data System (ADS)

    Datas, A.; López, E.; Ramiro, I.; Antolín, E.; Martí, A.; Luque, A.; Tamaki, R.; Shoji, Y.; Sogabe, T.; Okada, Y.

    2015-04-01

    We report, for the first time, about an intermediate band solar cell implemented with InAs/AlGaAs quantum dots whose photoresponse expands from 250 to ˜6000 nm . To our knowledge, this is the broadest quantum efficiency reported to date for a solar cell and demonstrates that the intermediate band solar cell is capable of producing photocurrent when illuminated with photons whose energy equals the energy of the lowest band gap. We show experimental evidences indicating that this result is in agreement with the theory of the intermediate band solar cell, according to which the generation recombination between the intermediate band and the valence band makes this photocurrent detectable.

  10. Waveguide circuits in three-dimensional photonic crystals

    SciTech Connect

    Biswas, Rana; Christensen, C.; Muehlmeier, J.; Tuttle, G.; Ho, K.-M.

    2008-04-07

    Waveguide circuits in three-dimensional photonic crystals with complete photonic band gaps are simulated with finite difference time domain (FDTD) simulations, and compared with measurements on microwave scale photonic crystals. The transmission through waveguide bends critically depends on the photonic crystal architecture in the bend region. We have found experimentally and theoretically, a new waveguide bend configuration consisting of overlapping rods in the bend region, that performs better than the simple waveguide bend of terminated rods, especially in the higher frequency portion of the band. Efficient beam splitters with this junction geometry are also simulated.

  11. A multi-functional superconductor single-photon detector at telecommunication wavelength

    NASA Astrophysics Data System (ADS)

    Zhang, Labao; Gu, Min; Jia, Tao; Qiu, Jian; Kang, Lin; Sun, Guozhu; Chen, Jian; Jin, Biaobin; Xu, Weiwei; Wu, Peiheng

    2014-06-01

    A multi-functional single-photon detector was demonstrated to resolve photon states by multiple superconductor single photon detectors (SSPDs) system with improved readout settings. The photon number and space distribution were resolved simultaneously by the presented system, which inherits the merits of SSPD, such as wide-response band, high repetition rate and working stability. Experimentally, four photons were resolved and the photon distribution over three pixels was figured out according to the amplitudes of output pulses at the telecommunication wavelength. The extension of this proposal to incorporate more elements for resolving more photons and revealing photons spatial distribution over larger scale is also discussed.

  12. Radiating dipoles in photonic crystals

    PubMed

    Busch; Vats; John; Sanders

    2000-09-01

    The radiation dynamics of a dipole antenna embedded in a photonic crystal are modeled by an initially excited harmonic oscillator coupled to a non-Markovian bath of harmonic oscillators representing the colored electromagnetic vacuum within the crystal. Realistic coupling constants based on the natural modes of the photonic crystal, i.e., Bloch waves and their associated dispersion relation, are derived. For simple model systems, well-known results such as decay times and emission spectra are reproduced. This approach enables direct incorporation of realistic band structure computations into studies of radiative emission from atoms and molecules within photonic crystals. We therefore provide a predictive and interpretative tool for experiments in both the microwave and optical regimes.

  13. Bernauer's bands.

    PubMed

    Shtukenberg, Alexander; Gunn, Erica; Gazzano, Massimo; Freudenthal, John; Camp, Eric; Sours, Ryan; Rosseeva, Elena; Kahr, Bart

    2011-06-01

    Ferdinand Bernauer proposed in his monograph, "Gedrillte" Kristalle (1929), that a great number of simple, crystalline substances grow from solution or from the melt as polycrystalline spherulites with helically twisting radii that give rise to distinct bull's-eye patterns of concentric optical bands between crossed polarizers. The idea that many common molecular crystals can be induced to grow as mesoscale helices is a remarkable proposition poorly grounded in theories of polycrystalline pattern formation. Recent reinvestigation of one of the systems Bernauer described revealed that rhythmic precipitation in the absence of helical twisting accounted for modulated optical properties [Gunn, E. et al. J. Am. Chem. Soc. 2006, 128, 14234-14235]. Herein, the Bernauer hypothesis is re-examined in detail for three substances described in "Gedrillte" Kristalle, potassium dichromate, hippuric acid, and tetraphenyl lead, using contemporary methods of analysis not available to Bernauer, including micro-focus X-ray diffraction, electron microscopy, and Mueller matrix imaging polarimetry. Potassium dichromate is shown to fall in the class of rhythmic precipitates of undistorted crystallites, while hippuric acid spherulites are well described as helical fibrils. Tetraphenyl lead spherulites grow by twisting and rhythmic precipitation. The behavior of tetraphenyl lead is likely typical of many substances in "Gedrillte" Kristalle. Rhythmic precipitation and helical twisting often coexist, complicating optical analyses and presenting Bernauer with difficulties in the characterization and classification of the objects of his interest.

  14. Absolute calibration of a charge-coupled device camera with twin beams

    SciTech Connect

    Meda, A.; Ruo-Berchera, I. Degiovanni, I. P.; Brida, G.; Rastello, M. L.; Genovese, M.

    2014-09-08

    We report on the absolute calibration of a Charge-Coupled Device (CCD) camera by exploiting quantum correlation. This method exploits a certain number of spatial pairwise quantum correlated modes produced by spontaneous parametric-down-conversion. We develop a measurement model accounting for all the uncertainty contributions, and we reach the relative uncertainty of 0.3% in low photon flux regime. This represents a significant step forward for the characterization of (scientific) CCDs used in mesoscopic light regime.

  15. Microalgae photonics

    NASA Astrophysics Data System (ADS)

    Floume, Timmy; Coquil, Thomas; Sylvestre, Julien

    2011-05-01

    Due to their metabolic flexibility and fast growth rate, microscopic aquatic phototrophs like algae have a potential to become industrial photochemical converters. Algae photosynthesis could enable the large scale production of clean and renewable liquid fuels and chemicals with major environmental, economic and societal benefits. Capital and operational costs are the main issues to address through optical, process and biochemical engineering improvements. In this perspective, a variety of photonic approaches have been proposed - we introduce them here and describe their potential, limitations and compatibility with separate biotechnology and engineering progresses. We show that only sunlight-based approaches are economically realistic. One of photonics' main goals in the algae field is to dilute light to overcome photosaturation effects that impact upon cultures exposed to full sunlight. Among other approaches, we introduce a widely-compatible broadband spectral adaptation technique called AlgoSun® that uses luminescence to optimize sunlight spectrum in view of the bioconverter's requirements.

  16. Energy bands and gaps near an impurity

    NASA Astrophysics Data System (ADS)

    Mihóková, E.; Schulman, L. S.

    2016-10-01

    It has been suggested that in the neighborhood of a certain kind of defect in a crystal there is a bend in the electronic band. We confirm that this is indeed possible using the Kronig-Penney model. Our calculations also have implications for photonic crystals.

  17. Thermoreflectance investigation of Th band structure

    SciTech Connect

    Colavita, E.; Paolucci, G.; Rosei, R.

    1982-06-15

    Thermoreflectance measurements have been carried out on thorium bulk samples at about 140 K in the 0.5--5-eV photon energy range. The data are interpreted within the framework of existing energy-band calculations. Several critical-point transitions and a Fermi-surface transition have been clearly identified and located in the Brillouin zone.

  18. Photon detectors

    SciTech Connect

    Va`vra, J.

    1995-10-01

    J. Seguinot and T. Ypsilantis have recently described the theory and history of Ring Imaging Cherenkov (RICH) detectors. In this paper, I will expand on these excellent review papers, by covering the various photon detector designs in greater detail, and by including discussion of mistakes made, and detector problems encountered, along the way. Photon detectors are among the most difficult devices used in physics experiments, because they must achieve high efficiency for photon transport and for the detection of single photo-electrons. For gaseous devices, this requires the correct choice of gas gain in order to prevent breakdown and wire aging, together with the use of low noise electronics having the maximum possible amplification. In addition, the detector must be constructed of materials which resist corrosion due to photosensitive materials such as, the detector enclosure must be tightly sealed in order to prevent oxygen leaks, etc. The most critical step is the selection of the photocathode material. Typically, a choice must be made between a solid (CsI) or gaseous photocathode (TMAE, TEA). A conservative approach favors a gaseous photocathode, since it is continuously being replaced by flushing, and permits the photon detectors to be easily serviced (the air sensitive photocathode can be removed at any time). In addition, it can be argued that we now know how to handle TMAE, which, as is generally accepted, is the best photocathode material available as far as quantum efficiency is concerned. However, it is a very fragile molecule, and therefore its use may result in relatively fast wire aging. A possible alternative is TEA, which, in the early days, was rejected because it requires expensive CaF{sub 2} windows, which could be contaminated easily in the region of 8.3 eV and thus lose their UV transmission.

  19. Suppression of thermal carrier escape and efficient photo-carrier generation by two-step photon absorption in InAs quantum dot intermediate-band solar cells using a dot-in-well structure

    SciTech Connect

    Asahi, S.; Teranishi, H.; Kasamatsu, N.; Kada, T.; Kaizu, T.; Kita, T.

    2014-08-14

    We investigated the effects of an increase in the barrier height on the enhancement of the efficiency of two-step photo-excitation in InAs quantum dot (QD) solar cells with a dot-in-well structure. Thermal carrier escape of electrons pumped in QD states was drastically reduced by sandwiching InAs/GaAs QDs with a high potential barrier of Al{sub 0.3}Ga{sub 0.7}As. The thermal activation energy increased with the introduction of the barrier. The high potential barrier caused suppression of thermal carrier escape and helped realize a high electron density in the QD states. We observed efficient two-step photon absorption as a result of the high occupancy of the QD states at room temperature.

  20. Cloud Height Retrieval with Oxygen A and B Bands for the Deep Space Climate Observatory (DSCOVR) Mission

    NASA Technical Reports Server (NTRS)

    Yang, Yuekui; Marshak, Alexander; Mao, Jianping; Lyapustin, Alexei; Herman, Jay

    2012-01-01

    Planned to fly in 2014, the Deep Space Climate Observatory (DSCOVR) would see the whole sunlit half of the Earth from the L 1 Lagrangian point and would provide simultaneous data on cloud and aerosol properties with its Earth Polychromatic Imaging Camera (EPIC). EPIC images the Earth on a 2Kx2K CCD array, which gives a horizontal resolution of about 10 km at nadir. A filter-wheel provides consecutive images in 10 spectral channels ranging from the UV to the near-IR, including the oxygen A and B bands. This paper presents a study of retrieving cloud height with EPIC's oxygen A and B bands. As the first step, we analyzed the effect of cloud optical and geometrical properties, sun-view geometry, and surface type on the cloud height determination. Second, we developed two cloud height retrieval algorithms that are based on the Mixed Lambertian-Equivalent Reflectivity (MLER) concept: one utilizes the absolute radiances at the Oxygen A and B bands and the other uses the radiance ratios between the absorption and reference channels of the two bands. Third, we applied the algorithms to the simulated EPIC data and to the data from SCanning Imaging Absorption SpectroMeter for Atmospheric CartograpHY (SCIAMACHY) observations. Results show that oxygen A and B bands complement each other: A band is better suited for retrievals over ocean, while B band is better over vegetated land due to a much darker surface. Improvements to the MLER model, including corrections to surface contribution and photon path inside clouds, will also be discussed.

  1. Butterfly wing color: A photonic crystal demonstration

    NASA Astrophysics Data System (ADS)

    Proietti Zaccaria, Remo

    2016-01-01

    We have theoretically modeled the optical behavior of a natural occurring photonic crystal, as defined by the geometrical characteristics of the Teinopalpus Imperialis butterfly. In particular, following a genetic algorithm approach, we demonstrate how its wings follow a triclinic crystal geometry with a tetrahedron unit base. By performing both photonic band analysis and transmission/reflection simulations, we are able to explain the characteristic colors emerging by the butterfly wings, thus confirming their crystal form.

  2. Jasminum flexile flower absolute from India--a detailed comparison with three other jasmine absolutes.

    PubMed

    Braun, Norbert A; Kohlenberg, Birgit; Sim, Sherina; Meier, Manfred; Hammerschmidt, Franz-Josef

    2009-09-01

    Jasminum flexile flower absolute from the south of India and the corresponding vacuum headspace (VHS) sample of the absolute were analyzed using GC and GC-MS. Three other commercially available Indian jasmine absolutes from the species: J. sambac, J. officinale subsp. grandiflorum, and J. auriculatum and the respective VHS samples were used for comparison purposes. One hundred and twenty-one compounds were characterized in J. flexile flower absolute, with methyl linolate, benzyl salicylate, benzyl benzoate, (2E,6E)-farnesol, and benzyl acetate as the main constituents. A detailed olfactory evaluation was also performed.

  3. Universal Cosmic Absolute and Modern Science

    NASA Astrophysics Data System (ADS)

    Kostro, Ludwik

    The official Sciences, especially all natural sciences, respect in their researches the principle of methodic naturalism i.e. they consider all phenomena as entirely natural and therefore in their scientific explanations they do never adduce or cite supernatural entities and forces. The purpose of this paper is to show that Modern Science has its own self-existent, self-acting, and self-sufficient Natural All-in Being or Omni-Being i.e. the entire Nature as a Whole that justifies the scientific methodic naturalism. Since this Natural All-in Being is one and only It should be considered as the own scientifically justified Natural Absolute of Science and should be called, in my opinion, the Universal Cosmic Absolute of Modern Science. It will be also shown that the Universal Cosmic Absolute is ontologically enormously stratified and is in its ultimate i.e. in its most fundamental stratum trans-reistic and trans-personal. It means that in its basic stratum. It is neither a Thing or a Person although It contains in Itself all things and persons with all other sentient and conscious individuals as well, On the turn of the 20th century the Science has begun to look for a theory of everything, for a final theory, for a master theory. In my opinion the natural Universal Cosmic Absolute will constitute in such a theory the radical all penetrating Ultimate Basic Reality and will substitute step by step the traditional supernatural personal Absolute.

  4. Absolute photoionization cross-section of the methyl radical.

    SciTech Connect

    Taatjes, C. A.; Osborn, D. L.; Selby, T.; Meloni, G.; Fan, H.; Pratt, S. T.; Chemical Sciences and Engineering Division; SNL

    2008-01-01

    The absolute photoionization cross-section of the methyl radical has been measured using two completely independent methods. The CH{sub 3} photoionization cross-section was determined relative to that of acetone and methyl vinyl ketone at photon energies of 10.2 and 11.0 eV by using a pulsed laser-photolysis/time-resolved synchrotron photoionization mass spectrometry method. The time-resolved depletion of the acetone or methyl vinyl ketone precursor and the production of methyl radicals following 193 nm photolysis are monitored simultaneously by using time-resolved synchrotron photoionization mass spectrometry. Comparison of the initial methyl signal with the decrease in precursor signal, in combination with previously measured absolute photoionization cross-sections of the precursors, yields the absolute photoionization cross-section of the methyl radical; {sigma}{sub CH}(10.2 eV) = (5.7 {+-} 0.9) x 10{sup -18} cm{sup 2} and {sigma}{sub CH{sub 3}}(11.0 eV) = (6.0 {+-} 2.0) x 10{sup -18} cm{sup 2}. The photoionization cross-section for vinyl radical determined by photolysis of methyl vinyl ketone is in good agreement with previous measurements. The methyl radical photoionization cross-section was also independently measured relative to that of the iodine atom by comparison of ionization signals from CH{sub 3} and I fragments following 266 nm photolysis of methyl iodide in a molecular-beam ion-imaging apparatus. These measurements gave a cross-section of (5.4 {+-} 2.0) x 10{sup -18} cm{sup 2} at 10.460 eV, (5.5 {+-} 2.0) x 10{sup -18} cm{sup 2} at 10.466 eV, and (4.9 {+-} 2.0) x 10{sup -18} cm{sup 2} at 10.471 eV. The measurements allow relative photoionization efficiency spectra of methyl radical to be placed on an absolute scale and will facilitate quantitative measurements of methyl concentrations by photoionization mass spectrometry.

  5. Structural characterization of thin film photonic crystals

    SciTech Connect

    Subramania, G.; Biswas, R.; Constant, K.; Sigalas, M. M.; Ho, K. M.

    2001-06-15

    We quantitatively analyze the structure of thin film inverse-opal photonic crystals composed of ordered arrays of air pores in a background of titania. Ordering of the sphere template and introduction of the titania background were performed simultaneously in the thin film photonic crystals. Nondestructive optical measurements of backfilling with high refractive index liquids, angle-resolved reflectivity, and optical spectroscopy were combined with band-structure calculations. The analysis reveals a thin film photonic crystal structure with a very high filling fraction (92{endash}94%) of air and a substantial compression along the c axis ({similar_to}22{endash}25%).

  6. Photonic crystal technology for terahertz system integration

    NASA Astrophysics Data System (ADS)

    Fujita, Masayuki; Nagatsuma, Tadao

    2016-04-01

    Developing terahertz integration technology is essential for practical use of terahertz electromagnetic waves (0.1-10 THz) in various applications including broadband wireless communication, spectroscopic sensing, and nondestructive imaging. In this paper, we present our recent challenges towards terahertz system integration based on photonic crystal technology such as the development of terahertz transceivers. We use photonic-crystal slabs consisting of a twodimensional lattice of air holes formed in a silicon slab to develop low loss compact terahertz components in planar structures. The demonstration of ultralow loss (< 0.1 dB/cm) waveguides and integrated transceiver devices in the 0.3 THz band shows the potential for the application of photonic crystals to terahertz integration technology. Improving the coupling efficiency between the photonic crystal waveguide and resonant tunneling diode is important to take full advantage of the ultralow loss photonic crystal waveguides.

  7. Pleiades Absolute Calibration : Inflight Calibration Sites and Methodology

    NASA Astrophysics Data System (ADS)

    Lachérade, S.; Fourest, S.; Gamet, P.; Lebègue, L.

    2012-07-01

    In-flight calibration of space sensors once in orbit is a decisive step to be able to fulfil the mission objectives. This article presents the methods of the in-flight absolute calibration processed during the commissioning phase. Four In-flight calibration methods are used: absolute calibration, cross-calibration with reference sensors such as PARASOL or MERIS, multi-temporal monitoring and inter-bands calibration. These algorithms are based on acquisitions over natural targets such as African deserts, Antarctic sites, La Crau (Automatic calibration station) and Oceans (Calibration over molecular scattering) or also new extra-terrestrial sites such as the Moon and selected stars. After an overview of the instrument and a description of the calibration sites, it is pointed out how each method is able to address one or several aspects of the calibration. We focus on how these methods complete each other in their operational use, and how they help building a coherent set of information that addresses all aspects of in-orbit calibration. Finally, we present the perspectives that the high level of agility of PLEIADES offers for the improvement of its calibration and a better characterization of the calibration sites.

  8. Quantum theory allows for absolute maximal contextuality

    NASA Astrophysics Data System (ADS)

    Amaral, Barbara; Cunha, Marcelo Terra; Cabello, Adán

    2015-12-01

    Contextuality is a fundamental feature of quantum theory and a necessary resource for quantum computation and communication. It is therefore important to investigate how large contextuality can be in quantum theory. Linear contextuality witnesses can be expressed as a sum S of n probabilities, and the independence number α and the Tsirelson-like number ϑ of the corresponding exclusivity graph are, respectively, the maximum of S for noncontextual theories and for the theory under consideration. A theory allows for absolute maximal contextuality if it has scenarios in which ϑ /α approaches n . Here we show that quantum theory allows for absolute maximal contextuality despite what is suggested by the examination of the quantum violations of Bell and noncontextuality inequalities considered in the past. Our proof is not constructive and does not single out explicit scenarios. Nevertheless, we identify scenarios in which quantum theory allows for almost-absolute-maximal contextuality.

  9. Absolute calibration in vivo measurement systems

    SciTech Connect

    Kruchten, D.A.; Hickman, D.P.

    1991-02-01

    Lawrence Livermore National Laboratory (LLNL) is currently investigating a new method for obtaining absolute calibration factors for radiation measurement systems used to measure internally deposited radionuclides in vivo. Absolute calibration of in vivo measurement systems will eliminate the need to generate a series of human surrogate structures (i.e., phantoms) for calibrating in vivo measurement systems. The absolute calibration of in vivo measurement systems utilizes magnetic resonance imaging (MRI) to define physiological structure, size, and composition. The MRI image provides a digitized representation of the physiological structure, which allows for any mathematical distribution of radionuclides within the body. Using Monte Carlo transport codes, the emission spectrum from the body is predicted. The in vivo measurement equipment is calibrated using the Monte Carlo code and adjusting for the intrinsic properties of the detection system. The calibration factors are verified using measurements of existing phantoms and previously obtained measurements of human volunteers. 8 refs.

  10. Stimulus probability effects in absolute identification.

    PubMed

    Kent, Christopher; Lamberts, Koen

    2016-05-01

    This study investigated the effect of stimulus presentation probability on accuracy and response times in an absolute identification task. Three schedules of presentation were used to investigate the interaction between presentation probability and stimulus position within the set. Data from individual participants indicated strong effects of presentation probability on both proportion correct and response times. The effects were moderated by the ubiquitous stimulus position effect. The accuracy and response time data were predicted by an exemplar-based model of perceptual cognition (Kent & Lamberts, 2005). The bow in discriminability was also attenuated when presentation probability for middle items was relatively high, an effect that will constrain future model development. The study provides evidence for item-specific learning in absolute identification. Implications for other theories of absolute identification are discussed. (PsycINFO Database Record

  11. Quantitative standards for absolute linguistic universals.

    PubMed

    Piantadosi, Steven T; Gibson, Edward

    2014-01-01

    Absolute linguistic universals are often justified by cross-linguistic analysis: If all observed languages exhibit a property, the property is taken to be a likely universal, perhaps specified in the cognitive or linguistic systems of language learners and users. In many cases, these patterns are then taken to motivate linguistic theory. Here, we show that cross-linguistic analysis will very rarely be able to statistically justify absolute, inviolable patterns in language. We formalize two statistical methods--frequentist and Bayesian--and show that in both it is possible to find strict linguistic universals, but that the numbers of independent languages necessary to do so is generally unachievable. This suggests that methods other than typological statistics are necessary to establish absolute properties of human language, and thus that many of the purported universals in linguistics have not received sufficient empirical justification.

  12. Absolute photoacoustic thermometry in deep tissue.

    PubMed

    Yao, Junjie; Ke, Haixin; Tai, Stephen; Zhou, Yong; Wang, Lihong V

    2013-12-15

    Photoacoustic thermography is a promising tool for temperature measurement in deep tissue. Here we propose an absolute temperature measurement method based on the dual temperature dependences of the Grüneisen parameter and the speed of sound in tissue. By taking ratiometric measurements at two adjacent temperatures, we can eliminate the factors that are temperature irrelevant but difficult to correct for in deep tissue. To validate our method, absolute temperatures of blood-filled tubes embedded ~9 mm deep in chicken tissue were measured in a biologically relevant range from 28°C to 46°C. The temperature measurement accuracy was ~0.6°C. The results suggest that our method can be potentially used for absolute temperature monitoring in deep tissue during thermotherapy.

  13. Molecular iodine absolute frequencies. Final report

    SciTech Connect

    Sansonetti, C.J.

    1990-06-25

    Fifty specified lines of {sup 127}I{sub 2} were studied by Doppler-free frequency modulation spectroscopy. For each line the classification of the molecular transition was determined, hyperfine components were identified, and one well-resolved component was selected for precise determination of its absolute frequency. In 3 cases, a nearby alternate line was selected for measurement because no well-resolved component was found for the specified line. Absolute frequency determinations were made with an estimated uncertainty of 1.1 MHz by locking a dye laser to the selected hyperfine component and measuring its wave number with a high-precision Fabry-Perot wavemeter. For each line results of the absolute measurement, the line classification, and a Doppler-free spectrum are given.

  14. Slab photonic crystals with dimer colloid bases

    SciTech Connect

    Riley, Erin K.; Liddell Watson, Chekesha M.

    2014-06-14

    The photonic band gap properties for centered rectangular monolayers of asymmetric dimers are reported. Colloids in suspension have been organized into the phase under confinement. The theoretical model is inspired by the range of asymmetric dimers synthesized via seeded emulsion polymerization and explores, in particular, the band structures as a function of degree of lobe symmetry and degree of lobe fusion. These parameters are varied incrementally from spheres to lobe-tangent dimers over morphologies yielding physically realizable particles. The work addresses the relative scarcity of theoretical studies on photonic crystal slabs with vertical variation that is consistent with colloidal self-assembly. Odd, even and polarization independent gaps in the guided modes are determined for direct slab structures. A wide range of lobe symmetry and degree of lobe fusion combinations having Brillouin zones with moderate to high isotropy support gaps between odd mode band indices 3-4 and even mode band indices 1-2 and 2-3.

  15. Photon Calorimeter

    DOEpatents

    Chow, Tze-Show

    1989-01-01

    A photon calorimeter (20, 40) is provided that comprises a laminar substrate (10, 22, 42) that is uniform in density and homogeneous in atomic composition. A plasma-sprayed coating (28, 48, 52), that is generally uniform in density and homogeneous in atomic composition within the proximity of planes that are parallel to the surfaces of the substrate, is applied to either one or both sides of the laminar substrate. The plasma-sprayed coatings may be very efficiently spectrally tailored in atomic number. Thermocouple measuring junctions (30, 50, 54) are positioned within the plasma-sprayed coatings. The calorimeter is rugged, inexpensive, and equilibrates in temperature very rapidly.

  16. Photon calorimeter

    DOEpatents

    Chow, Tze-Show

    1988-04-22

    A photon calorimeter is provided that comprises a laminar substrate that is uniform in density and homogeneous in atomic composition. A plasma-sprayed coating, that is generally uniform in density and homogeneous in atomic composition within the proximity of planes that are parallel to the surfaces of the substrate, is applied to either one or both sides of the laminar substrate. The plasma-sprayed coatings may be very efficiently spectrally tailored in atomic number. Thermocouple measuring junctions, are positioned within the plasma-sprayed coatings. The calorimeter is rugged, inexpensive, and equilibrates in temperature very rapidly. 4 figs.

  17. Updated Absolute Flux Calibration of the COS FUV Modes

    NASA Astrophysics Data System (ADS)

    Massa, D.; Ely, J.; Osten, R.; Penton, S.; Aloisi, A.; Bostroem, A.; Roman-Duval, J.; Proffitt, C.

    2014-03-01

    We present newly derived point source absolute flux calibrations for the COS FUV modes at both the original and second lifetime positions. The analysis includes observa- tions through the Primary Science Aperture (PSA) of the standard stars WD0308-565, GD71, WD1057+729 and WD0947+857 obtained as part of two calibration programs. Data were were obtained for all of the gratings at all of the original CENWAVE settings at both the original and second lifetime positions and for the G130M CENWAVE = 1222 at the second lifetime position. Data were also obtained with the FUVB segment for the G130M CENWAVE = 1055 and 1096 setting at the second lifetime position. We also present the derivation of L-flats that were used in processing the data and show that the internal consistency of the primary standards is 1%. The accuracy of the absolute flux calibrations over the UV are estimated to be 1-2% for the medium resolution gratings, and 2-3% over most of the wavelength range of the G140L grating, although the uncertainty can be as large as 5% or more at some G140L wavelengths. We note that these errors are all relative to the optical flux near the V band and small additional errors may be present due to inaccuracies in the V band calibration. In addition, these error estimates are for the time at which the flux calibration data were obtained; the accuracy of the flux calibration at other times can be affected by errors in the time dependent sensitivity (TDS) correction.

  18. Doppler-free two-photon excitation spectroscopy and the Zeeman effects of the S1 1B1u(v21=1) <-- S0 1Ag(v=0) band of naphthalene-d8.

    PubMed

    Okubo, Mitsushi; Wang, Jinguo; Baba, Masaaki; Misono, Masatoshi; Kasahara, Shunji; Katô, Hajime

    2005-04-01

    Doppler-free two-photon excitation spectrum and the Zeeman effect of the S1 1B1u(v21=1) <-- S0 1Ag(v=0) transition of naphthalene-d8 have been measured. 908 lines of Q(Ka)Q(J)KaKc transition of J=0-41, Ka=0-20 were assigned, and the molecular constants of the S1 1B1u(v21=1) state were determined. Perturbations were observed, and those were identified as originating from Coriolis interaction. No perturbation originating from an interaction with triplet state was observed. The Zeeman splittings from lines of a given J were observed to increase with Kc, and those of the Kc=J levels increased linearly with J. The Zeeman effects are shown to be originating from the magnetic moment of the S1 1B1u state, which is along the c axis and is induced by mixing of the S2 1B3u state to the S1 1B1u state by J-L coupling. Rotationally resolved levels were found not to be mixed with a triplet state from the Zeeman spectra. Accordingly, it is concluded that nonradiative decay of an isolated naphthalene excited to low rovibronic levels in the S1 1B1u state does not occur through the intersystem mixing. This is at variance with generally accepted understanding of the pathways of the nonradiative decay.

  19. Photonic states deep into the waveguide cutoff frequency of metallic mesh photonic crystal filters

    NASA Astrophysics Data System (ADS)

    Sang, Hong-Yi; Li, Zhi-Yuan; Gu, Ben-Yuan

    2005-02-01

    We examine the optical properties of three-dimensional metallic photonic crystals made from a periodic stacking of thin metallic mesh layers separated by homogeneous dielectric films by means of a combination of the plane-wave-based transfer-matrix method and analytical modal solution approach. Although each metallic mesh layer can serve as a frequency-selective surface and involves an intrinsic long-wavelength waveguide cutoff to electromagnetic waves, pass bands and new band gaps can exist far below the cutoff frequency due to the global coupling effect among different mesh layers. The results for the transmission spectra and photonic band structures are in good agreement with existing experimental measurements. It is found that the position of the pass bands and band gaps strongly depends on the thickness and composite of the separation layer between the adjacent metallic mesh layers.

  20. Photonic crystal surface-emitting lasers enabled by an accidental Dirac point

    SciTech Connect

    Chua, Song Liang; Lu, Ling; Soljacic, Marin

    2014-12-02

    A photonic-crystal surface-emitting laser (PCSEL) includes a gain medium electromagnetically coupled to a photonic crystal whose energy band structure exhibits a Dirac cone of linear dispersion at the center of the photonic crystal's Brillouin zone. This Dirac cone's vertex is called a Dirac point; because it is at the Brillouin zone center, it is called an accidental Dirac point. Tuning the photonic crystal's band structure (e.g., by changing the photonic crystal's dimensions or refractive index) to exhibit an accidental Dirac point increases the photonic crystal's mode spacing by orders of magnitudes and reduces or eliminates the photonic crystal's distributed in-plane feedback. Thus, the photonic crystal can act as a resonator that supports single-mode output from the PCSEL over a larger area than is possible with conventional PCSELs, which have quadratic band edge dispersion. Because output power generally scales with output area, this increase in output area results in higher possible output powers.

  1. Absolute Stability And Hyperstability In Hilbert Space

    NASA Technical Reports Server (NTRS)

    Wen, John Ting-Yung

    1989-01-01

    Theorems on stabilities of feedback control systems proved. Paper presents recent developments regarding theorems of absolute stability and hyperstability of feedforward-and-feedback control system. Theorems applied in analysis of nonlinear, adaptive, and robust control. Extended to provide sufficient conditions for stability in system including nonlinear feedback subsystem and linear time-invariant (LTI) feedforward subsystem, state space of which is Hilbert space, and input and output spaces having finite numbers of dimensions. (In case of absolute stability, feedback subsystem memoryless and possibly time varying. For hyperstability, feedback system dynamical system.)

  2. Octonacci photonic quasicrystals

    NASA Astrophysics Data System (ADS)

    Brandão, E. R.; Costa, C. H.; Vasconcelos, M. S.; Anselmo, D. H. A. L.; Mello, V. D.

    2015-08-01

    We study theoretically the transmission spectra in one-dimensional photonic quasicrystals, made up of SiO2(A) and TiO2(B) materials, organized following the Octonacci sequence, where the nth-stage of the multilayer Sn is given by the rule Sn =Sn-1Sn-2Sn-1 , for n ⩾ 3 and with S1 = A and S2 = B . The expression for transmittance was obtained by employing a theoretical calculation based on the transfer-matrix method. For normally incident waves, we observe that, for a same generation, the transmission spectra for transverse electric (TE) and transverse magnetic (TM) waves are equal, at least qualitatively, and they present a scaling property where a self-similar behavior is obtained, as an evidence that these spectra are fractals. The spectra show regions where the omnidirectional band gaps emerges for specific generations of Octonacci photonic structure, except to TM waves. For TE waves, we note that all of them have almost the same width, for different generations. We also report the localization of modes as a consequence of the quasiperiodicity of the heterostructure.

  3. Magneto-photonic crystals for optical sensing applications

    NASA Astrophysics Data System (ADS)

    Dissanayake, Neluka

    Among the optical structures investigated for optical sensing purpose, a significant amount of research has been conducted on photonic crystal based sensors. A particular advantage of photonic crystal based sensors is that they show superior sensitivity for ultra-small volume sensing. In this study we investigate polarization changes in response to the changes in the cover index of magneto-optic active photonic band gap structures. One-dimensional photonic-band gap structures fabricated on iron garnet materials yield large polarization rotations at the band gap edges. The enhanced polarization effects serve as an excellent tool for chemical sensing showing high degree of sensitivity for photonic crystal cover refractive index changes. The one dimensional waveguide photonic crystals are fabricated on single-layer bismuth-substituted rare earth iron garnet films ((Bi, Y, Lu)3(Fe, Ga)5O12 ) grown by liquid phase epitaxy on gadolinium gallium garnet substrates. Band gaps have been observed where Bragg scattering conditions links forward-going fundamental waveguide modes to backscattered high-order waveguide modes. Large near-band-edge polarization rotations which increase progressively with backscattered-mode order have been experimentally demonstrated for multiple samples with different composition, film thickness and fabrication parameters. Experimental findings are supported by theoretical analysis of Bloch modes polarization states showing that large near stop-band edge rotations are induced by the magneto-photonic crystal. Theoretical and experimental analysis conducted on polarization rotation sensitivity to waveguide photonic crystal cover refractive index changes shows a monotonic enhancement of the rotation with cover index. The sensor is further developed for selective chemical sensing by employing Polypyrrole as the photonic crystal cover layer. Polypyrrole is one of the extensively studied conducting polymers for selective analyte detection. Successful

  4. Direct detection of a single photon by humans.

    PubMed

    Tinsley, Jonathan N; Molodtsov, Maxim I; Prevedel, Robert; Wartmann, David; Espigulé-Pons, Jofre; Lauwers, Mattias; Vaziri, Alipasha

    2016-01-01

    Despite investigations for over 70 years, the absolute limits of human vision have remained unclear. Rod cells respond to individual photons, yet whether a single-photon incident on the eye can be perceived by a human subject has remained a fundamental open question. Here we report that humans can detect a single-photon incident on the cornea with a probability significantly above chance. This was achieved by implementing a combination of a psychophysics procedure with a quantum light source that can generate single-photon states of light. We further discover that the probability of reporting a single photon is modulated by the presence of an earlier photon, suggesting a priming process that temporarily enhances the effective gain of the visual system on the timescale of seconds. PMID:27434854

  5. Direct detection of a single photon by humans

    PubMed Central

    Tinsley, Jonathan N.; Molodtsov, Maxim I.; Prevedel, Robert; Wartmann, David; Espigulé-Pons, Jofre; Lauwers, Mattias; Vaziri, Alipasha

    2016-01-01

    Despite investigations for over 70 years, the absolute limits of human vision have remained unclear. Rod cells respond to individual photons, yet whether a single-photon incident on the eye can be perceived by a human subject has remained a fundamental open question. Here we report that humans can detect a single-photon incident on the cornea with a probability significantly above chance. This was achieved by implementing a combination of a psychophysics procedure with a quantum light source that can generate single-photon states of light. We further discover that the probability of reporting a single photon is modulated by the presence of an earlier photon, suggesting a priming process that temporarily enhances the effective gain of the visual system on the timescale of seconds. PMID:27434854

  6. Bose-Einstein condensation of photons in a 'white-wall' photon box

    NASA Astrophysics Data System (ADS)

    Klärs, Jan; Schmitt, Julian; Vewinger, Frank; Weitz, Martin

    2011-01-01

    Bose-Einstein condensation, the macroscopic ground state occupation of a system of bosonic particles below a critical temperature, has been observed in cold atomic gases and solid-state physics quasiparticles. In contrast, photons do not show this phase transition usually, because in Planck's blackbody radiation the particle number is not conserved and at low temperature the photons disappear in the walls of the system. Here we report on the realization of a photon Bose-Einstein condensate in a dye-filled optical microcavity, which acts as a "white-wall" photon box. The cavity mirrors provide a trapping potential and a non-vanishing effective photon mass, making the system formally equivalent to a two-dimensional gas of trapped massive bosons. Thermalization of the photon gas is reached in a number conserving way by multiple scattering off the dye molecules. Signatures for a BEC upon increased photon density are: a spectral distribution that shows Bose-Einstein distributed photon energies with a macroscopically populated peak on top of a broad thermal wing, the observed threshold of the phase transition showing the predicted absolute value and scaling with resonator geometry, and condensation appearing at the trap centre even for a spatially displaced pump spot.

  7. Absolute Points for Multiple Assignment Problems

    ERIC Educational Resources Information Center

    Adlakha, V.; Kowalski, K.

    2006-01-01

    An algorithm is presented to solve multiple assignment problems in which a cost is incurred only when an assignment is made at a given cell. The proposed method recursively searches for single/group absolute points to identify cells that must be loaded in any optimal solution. Unlike other methods, the first solution is the optimal solution. The…

  8. Absolute partial photoionization cross sections of ozone.

    SciTech Connect

    Berkowitz, J.; Chemistry

    2008-04-01

    Despite the current concerns about ozone, absolute partial photoionization cross sections for this molecule in the vacuum ultraviolet (valence) region have been unavailable. By eclectic re-evaluation of old/new data and plausible assumptions, such cross sections have been assembled to fill this void.

  9. Stimulus Probability Effects in Absolute Identification

    ERIC Educational Resources Information Center

    Kent, Christopher; Lamberts, Koen

    2016-01-01

    This study investigated the effect of stimulus presentation probability on accuracy and response times in an absolute identification task. Three schedules of presentation were used to investigate the interaction between presentation probability and stimulus position within the set. Data from individual participants indicated strong effects of…

  10. Teaching Absolute Value Inequalities to Mature Students

    ERIC Educational Resources Information Center

    Sierpinska, Anna; Bobos, Georgeana; Pruncut, Andreea

    2011-01-01

    This paper gives an account of a teaching experiment on absolute value inequalities, whose aim was to identify characteristics of an approach that would realize the potential of the topic to develop theoretical thinking in students enrolled in prerequisite mathematics courses at a large, urban North American university. The potential is…

  11. Solving Absolute Value Equations Algebraically and Geometrically

    ERIC Educational Resources Information Center

    Shiyuan, Wei

    2005-01-01

    The way in which students can improve their comprehension by understanding the geometrical meaning of algebraic equations or solving algebraic equation geometrically is described. Students can experiment with the conditions of the absolute value equation presented, for an interesting way to form an overall understanding of the concept.

  12. Increasing Capacity: Practice Effects in Absolute Identification

    ERIC Educational Resources Information Center

    Dodds, Pennie; Donkin, Christopher; Brown, Scott D.; Heathcote, Andrew

    2011-01-01

    In most of the long history of the study of absolute identification--since Miller's (1956) seminal article--a severe limit on performance has been observed, and this limit has resisted improvement even by extensive practice. In a startling result, Rouder, Morey, Cowan, and Pfaltz (2004) found substantially improved performance with practice in the…

  13. On Relative and Absolute Conviction in Mathematics

    ERIC Educational Resources Information Center

    Weber, Keith; Mejia-Ramos, Juan Pablo

    2015-01-01

    Conviction is a central construct in mathematics education research on justification and proof. In this paper, we claim that it is important to distinguish between absolute conviction and relative conviction. We argue that researchers in mathematics education frequently have not done so and this has lead to researchers making unwarranted claims…

  14. Reciprocity theorem and perturbation theory for photonic crystal waveguides.

    PubMed

    Michaelis, D; Peschel, U; Wächter, C; Bräuer, A

    2003-12-01

    Starting from Maxwell's equations we derive a reciprocity theorem for photonic crystal waveguides. A set of strongly coupled discrete equations results, which can be applied to the simulation of perturbed photonic crystal waveguides. As an example we analytically study the influence of the dispersion of a two level system on the band structure of a photonic crystal waveguide. In particular, the formation of polariton gaps is discussed.

  15. Optical limiter based on two-dimensional nonlinear photonic crystals

    NASA Astrophysics Data System (ADS)

    Belabbas, Amirouche; Lazoul, Mohamed

    2016-04-01

    The aim behind this work is to investigate the capabilities of nonlinear photonic crystals to achieve ultra-fast optical limiters based on third order nonlinear effects. The purpose is to combine the actions of nonlinear effects with the properties of photonic crystals in order to activate the photonic band according to the magnitude of the nonlinear effects, themselves a function of incident laser power. We are interested in designing an optical limiter based nonlinear photonic crystal operating around 1064 nm and its second harmonic at 532 nm. Indeed, a very powerful solid-state laser that can blind or destroy optical sensors and is widely available and easy to handle. In this work, we perform design and optimization by numerical simulations to determine the better structure for the nonlinear photonic crystal to achieve compact and efficient integrated optical limiter. The approach consists to analyze the band structures in Kerr-nonlinear two-dimensional photonic crystals as a function of the optical intensity. We confirm that these bands are dynamically red-shifted with regard to the bands observed in linear photonic crystals or in the case of weak nonlinear effects. The implemented approach will help to understand such phenomena as intensitydriven optical limiting with Kerr-nonlinear photonic crystals.

  16. [Recent advancement of photonic-crystal-based analytical chemistry].

    PubMed

    Chen, Yun; Guo, Zhenpeng; Wang, Jinyi; Chen, Yi

    2014-04-01

    Photonic crystals are a type of novel materials with ordered structure, nanopores/channels and optical band gap. They have hence important applications in physics, chemistry, biological science and engineering fields. This review summarizes the recent advancement of photonic crystals in analytical chemistry applications, with focus on sensing and separating fields happening in the nearest 5 years.

  17. Jets and Photons

    NASA Astrophysics Data System (ADS)

    Ellis, Stephen D.; Roy, Tuhin S.; Scholtz, Jakub

    2013-03-01

    This Letter applies the concept of “jets,” as constructed from calorimeter cell four-vectors, to jets composed (primarily) of photons (or leptons). Thus jets become a superset of both traditional objects such as QCD jets, photons, and electrons, and more unconventional objects such as photon jets and electron jets, defined as collinear photons and electrons, respectively. Since standard objects such as single photons become a subset of jets in this approach, standard jet substructure techniques are incorporated into the photon finder toolbox. Using a (reasonably) realistic calorimeter model we demonstrate that, for a single photon identification efficiency of 80% or above, the use of jet substructure techniques reduces the number of QCD jets faking photons by factors of 2.5 to 4. Depending on the topology of the photon jets, the substructure variables reduce the number of photon jets faking single photons by factors of 10 to 103 at a single photon identification efficiency of 80%.

  18. Laparoscopic gastric banding - discharge

    MedlinePlus

    ... laparoscopic gastric banding - discharge; Obesity gastric banding discharge; Weight loss - gastric banding discharge ... as your body gets used to your weight loss and your weight becomes stable. Weight loss may be slower after ...

  19. Using Correlated Photons to Suppress Background Noise

    NASA Technical Reports Server (NTRS)

    Jackson, Deborah; Hockney, George; Dowling, Jonathan

    2003-01-01

    A proposed method of suppressing the effect of background noise in an optical communication system would exploit the transmission and reception of correlated photons at the receiver. The method would not afford any advantage in a system in which performance is limited by shot noise. However, if the performance of the system is limited by background noise (e.g., sunlight in the case of a free-space optical communication system or incoherently scattered in-band photons in the case of a fiber-optic communication system), then the proposed method could offer an advantage: the proposed method would make it possible to achieve a signal-to-noise ratio (S/N) significantly greater than that of an otherwise equivalent background- noise-limited optical communication system based on the classical transmission and reception of uncorrelated photons. The figure schematically depicts a classical optical-communication system and a system according to the proposed method. In the classical system, a modulated laser beam is transmitted along an optical path to a receiver, the optics of which include a narrow-band-pass filter that suppresses some of the background noise. A photodetector in the receiver detects the laser-beam and background photons, most or all of which are uncorrelated. In the proposed system, correlated photons would be generated at the transmitter by making a modulated laser beam pass through a nonlinear parametric down-conversion crystal. The sum of frequencies of the correlated photons in each pair would equal the frequency of the incident photon from which they were generated. As in the classical system, the correlated photons would travel along an optical path to a receiver, where they would be band-pass filtered and detected. Unlike in the classical system, the photodetector in the receiver in this system would be one that intrinsically favors the detection of pairs of correlated photons over the detection of uncorrelated photons. Even though there would be no

  20. Preparation and formation mechanism of three-dimensionally ordered macroporous (3DOM) MgO, MgSO{sub 4}, CaCO{sub 3}, and SrCO{sub 3}, and photonic stop band properties of 3DOM CaCO{sub 3}

    SciTech Connect

    Sadakane, Masahiro; Kato, Rika; Murayama, Toru; Ueda, Wataru

    2011-08-15

    Three-dimensionally ordered macroporous (3DOM) magnesium (Mg) oxide (MgO), MgSO{sub 4}, calcium (Ca) carbonate (CaCO{sub 3}), and strontium (Sr) carbonate (SrCO{sub 3}) were prepared using a colloidal crystal of polymer spheres as a template. Ethanol or ethanol-water solution of metal salts (acetate or nitrate) and citric acid was infiltrated into the void of the colloidal crystal template of a monodispersed poly(methyl methacrylate) (PMMA) sphere. Heating of this PMMA-metal salt-citric acid composite produced the desired well-ordered 3DOM materials with a high pore fraction, which was confirmed by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and ultraviolet-visible (UV-vis) diffuse reflectance spectra. The presence of citric acid is crucial for production of the 3DOM structures. Reaction of citric acid with metal salt produces metal citrate solid in the void of PMMA spheres, which is necessary to maintain the 3DOM structure during the calcination process. 3DOM CaCO{sub 3} shows opalescent colors because of it's photonic stop band properties. - Graphical abstract: Well-ordered 3-dimensionally ordered macroporous MgO, MgSO{sub 4}, CaCO{sub 3}, and SrCO{sub 3} materials were obtained in a high pore fraction. Highlights: > An easy preparation method of 3D ordered macroporous (3DOM) MgO, MgSO{sub 4}, CaCO{sub 3}, and SrCO{sub 3} materials. > Their structural characterization. > Their formation mechanism. > Photonic properties of 3DOM CaCO{sub 3}.