Sample records for step index fiber

  1. Dye-doped step-index polymer optical fiber for broadband optical amplification

    Microsoft Academic Search

    Gang Ding Peng; P. K. Chu; Zhengjun Xiong; Trevor W. Whitbread; Rod P. Chaplin

    1996-01-01

    We report the development of a novel and simple technique for fabricating polymer optical fibers of good optical quality for special device applications. This technique aims at polymer fibers doped with various functional organic materials. On the basis of the technique, step-index polymer optical fibers doped with laser dyes have been fabricated. High-gain and high-efficiency optical amplification has been achieved

  2. Large diameter step-index multimode fiber speckle reduction device based on time coherence theory

    NASA Astrophysics Data System (ADS)

    Lu, Chunlian; Fu, Hongyuan; Huang, Zhongjun; Sun, Weimin

    2012-11-01

    A fiber speckle reduction device designed and made based on time coherence theory was introduced in this paper according to the decisive influence of mode dispersion existed in signal transmission of large diameter step-index multimode fiber. Through the contrast experinent verification under different exposure time, the device can effectively suppress speckle noise of fiber and improve signal contrast. The device introduced in this paper will have a good application prospect in the fields of laser lighting monitoring system, multimode fiber property test system, laser mapping system, ect.

  3. Bi2O3-based highly nonlinear fiber with step index structure

    NASA Astrophysics Data System (ADS)

    Nagashima, Tatsuo; Hasegawa, Tomoharu; Ohara, Seiki; Sugimoto, Naoki; Taira, Kenji; Kikuchi, Kazuro

    2004-06-01

    Bismuth oxide based highly nonlinear fiber (Bi-NLF) enabled by glass composition and small core fiber design was successfully fabricated. There's much expectation for the development of high nonlinearity optical devices along with the large volumetric and speed increase of the information traffic in recent years. In order to achieve higher nonlinearity, it is necessary to enlarge the nonlinear refractive index n2 and make the effective core area Aeff smaller, as g is ?=2?n2/(?Aeff). Much effort has been put into the development of small-Aeff holey fiber, as its high nonlinearity and dispersion can be controlled to a certain extent. However, holey fiber has issues such as large propagation loss, high connection loss with silica single-mode-fiber (SMF) because of their particular structure, and higher fabrication cost. We performed the fabrication of a conventional step-index-type SMF with high nonlinearity and low propagation loss using Bi2O3-based glass. First, we fabricated Bi2O3-based glass with high refractive index of >2.2 at 1550 nm by a conventional melting method. This glass exhibited extreme thermal stability for fiber drawing. Then in order to make Aeff smaller, cladding glass composition was designed so that the difference with the refractive index of the core glass must be large. Finally the core diameter was controlled to satisfy the single mode condition, and fiber drawing was performed. Typical Aeff of this fiber is less than 5 um2. The nonlinearity g of the fiber can be estimated to be >600 W-1km-1, as large as the value reported in holey fibers using non-silica glass. Bi-NLF with step-index-type structure would become the best candidate for short length and highly nonlinear optical devices.

  4. Frequency response and bandwidth in low-numerical-aperture step-index plastic optical fibers.

    PubMed

    Savovi?, Svetislav; Drlja?a, Branko; Kova?evi?, Milan S; Djordjevich, Alexandar; Baji?, Jovan S; Stupar, Dragan Z; Stepniak, Grzegorz

    2014-10-20

    By experimental measurement and from a numerical solution to the time-dependent power flow equation, the frequency response, bandwidth, mode coupling, and mode-dependent attenuation are determined for a low-numerical-aperture (NA) plastic optical fiber. Frequency response and bandwidth are specified as a function of fiber length. Numerical results are verified against experimental measurements. Mode coupling and modal attenuation are found to differ substantially between two fiber varieties of the same type (both low-NA, step-index, and plastic), implying their preferential suitability that is application-specific. PMID:25402786

  5. Discrete Multitone Modulation for Maximizing Transmission Rate in Step-Index Plastic Optical Fibers

    Microsoft Academic Search

    S. C. Jeffrey Lee; Florian Breyer; Sebastian Randel; Roberto Gaudino; Gabriella Bosco; Andreas Bluschke; Michael Matthews; Philipp Rietzsch; Rainer Steglich; Henrie P. A. van den Boom; Antonius M. J. Koonen

    2009-01-01

    The use of standard 1-mm core-diameter step-index plastic optical fiber (SI-POF) has so far been mainly limited to distances of up to 100 m and bit-rates in the order of 100 Mbit\\/s. By use of digital signal processing, transmission performance of such optical links can be improved. Among the different technical solutions proposed, a promising one is based on the

  6. Plasmon resonances on gold nanowires directly drawn in a step-index fiber.

    PubMed

    Tyagi, H K; Lee, H W; Uebel, P; Schmidt, M A; Joly, N; Scharrer, M; Russell, P St J

    2010-08-01

    We report the successful production of high-quality gold wires, with diameters down to 260nm, by direct fiber drawing from a gold-filled fused-silica cane. The stack-and-draw technique makes it straightforward to incorporate a conventional step-index core, adjacent to the gold wire, in the cane. In the drawn fiber, strong coupling of light from the glass core to SPP resonances on the gold wire is observed at specific well-defined wavelengths. Such embedded wires have many potential applications, for example, as nanoscale electrodes, in nonlinear optical plasmonics, and as near-field scanning optical microscope tips. PMID:20680062

  7. Efficiency of various modulation types in Step Index Polymer Optical Fiber

    NASA Astrophysics Data System (ADS)

    Siuzdak, Jerzy; Stepniak, Grzegorz

    2014-11-01

    Efficiency of PAM, CAP/QAM and OFDM/DMT modulation for Step Index Polymer Optical Fiber channel is analyzed theoretically. It is shown that for the same transmitted optical power and same BER they offer similar data throughputs. However, when the light source has limited dynamics the crucial factor is the peak to average power ratio of the modulating signal. This is the greatest for OFDM/DMT and smaller for CAP and PAM. Consequently, the efficiency for PAM and CAP should be comparable whereas that of DMT - inferior. This conclusion was confirmed by experimental results.

  8. Design of mode scramblers for step-index and graded-index plastic optical fibers

    Microsoft Academic Search

    J. Arrue; G. Aldabaldetreku; G. Durana; J. Zubia; I. Garces; F. Jiménez

    2005-01-01

    We analyze the internal evolution of light power angular distribution in typical mode scrambling configurations by comparing the resultant far fields, obtained either experimentally or computationally, with the experimental equilibrium mode distribution (EMD) far field for the plastic optical fibers (POF) considered, so as to provide an insight that helps to adapt existing scramblers to new types of POF that

  9. Splicing Hollow-Core Photonic Bandgap Fibers to Step-Index Fibers Using an Arc Fusion Splicer

    E-print Network

    Washburn, Brian

    FiberSMF Fiber Fiber Splicer Electrodes Gap Optical Power Meter Axis 1550 nm Diode Laser PBG FiberSMF Fiber Fiber Splicer Electrodes Gap Optical Power Meter Axis 1550 nm Diode Laser Fig. 1. (a) Experimental) A micrograph showing the splice between the SMF and PBG fiber. Picture courtesy of the GaN Group at KSU Physics

  10. Experimental investigation of PAM, CAP and DMT modulations efficiency over a double-step-index polymer optical fiber

    NASA Astrophysics Data System (ADS)

    Stepniak, G.; Siuzdak, J.

    2014-08-01

    Investigated was the transmission over step index POF that is 50 m/100 m long with a red DVD laser as a source and a Si p-i-n commercial photo-detector. The maximum bit rates of three modulation formats: PAM, CAP and DMT were sought. Their constellation sizes and symbol rates were varied in order to maximize FEC limited throughputs for each modulation whereas the laser operating point and relevant optical powers were maintained constant for all the modulations. The maximum throughputs were similar for PAM and CAP, namely 3.3/2 Gbit/s for PAM, and 3.15/2.1 for CAP for 50/100 m fiber, respectively. The bit rates for DMT were 2.65/1.65 Gbit/s for the respective lengths of the fiber. We attribute the inferior performance of DMT to its high value of peak to average power ratio.

  11. High peak- and average-power pulse shaped fiber laser in the ns-regime applying step-index XLMA gain fibers

    NASA Astrophysics Data System (ADS)

    Dinger, R.; Grundmann, F.-P.; Hapke, C.; Ruppik, S.

    2014-03-01

    Pulsed fiber lasers and continuous-wave (cw) fiber lasers have become the tool of choice in more and more laser based industrial applications like metal cutting and welding mainly because of their robustness, compactness, high brightness, high efficiency and reasonable costs. However, to further increase the productivity with those laser types there is a great demand for even higher laser power specifications. In this context we demonstrate a pulsed high peak- and averagepower fiber laser in a Master Oscillator Power Amplifier (MOPA) configuration with selectable pulse durations between 1 ns and several hundred nanoseconds. To overcome fiber nonlinearities such as stimulated Raman scattering (SRS) and self-phase-modulation (SPM) flexible Ytterbium doped extra-large mode area (XLMA) step index fibers, prepared by novel powder-sinter technology, have been used as gain fibers. As an example, for 12 ns pulses with a repetition rate of 10 kHz, a pump power limited average laser output power of more than 400 W in combination with peak powers of more than 3.5 MW (close to self-focusing-threshold) has been achieved in stable operation. The potentials of this laser system have been further explored towards longer pulse durations in order to achieve even higher pulse energies by means of pulse shaping techniques. In addition, investigations have been conducted with reduced pulse energies and repetition rates up to 500 kHz and average powers of more than 500 W at nearly diffraction limited beam quality.

  12. Space-time block code based MIMO encoding for large core step index plastic optical fiber transmission systems.

    PubMed

    Raptis, Nikos; Grivas, Evangelos; Pikasis, Evangelos; Syvridis, Dimitris

    2011-05-23

    The performance of Space-Time Block Codes combined with Discrete MultiTone modulation applied in a Large Core Step-Index POF link is examined theoretically. A comparative study is performed considering several schemes that employ multiple transmitters/receivers and a fiber span of 100 m. The performance enhancement of the higher diversity order configurations is revealed by application of a Margin Adaptive Bit Loading technique that employs Chow's algorithm. Simulations results of the above schemes, in terms of Bit Error Rate as a function of the received Signal to Noise Ratio, are provided. An improvement of more than 6 dB for the required electrical SNR is observed for a 3 × 1 configuration, in order to achieve a 10(-3) BER value, as compared to a conventional Single Input Single output scheme. PMID:21643291

  13. High-power mid-infrared high repetition-rate supercontinuum source based on a chalcogenide step-index fiber.

    PubMed

    Kedenburg, Stefan; Steinle, Tobias; Mörz, Florian; Steinmann, Andy; Giessen, Harald

    2015-06-01

    We demonstrate a tunable and robust femtosecond supercontinuum source with a maximum output power of 550 mW and a maximum spectral width of up to 2.0 ?m, which can cover the mid-infrared region from 2.3 ?m up to 4.9 ?m by tuning the pump wavelength. As2S3 chalcogenide step-index fibers with core diameters of 7 and 9 ?m are pumped at different wavelengths from 2.5 ?m up to 4.1 ?m with femtosecond pulses by means of a post-amplified optical parametric oscillator pumped by an Yb:KGW laser. The spectral behavior of the supercontinuum is investigated by changing the pump wavelength, core diameter, fiber length, and pump power. Self-phase modulation is identified as the main broadening mechanism in the normal dispersion regime. This source promises to be an excellent laboratory tool for infrared spectroscopy owing to its high brilliance as demonstrated for the CS2-absorption bands around 3.5 ?m. PMID:26030585

  14. Simplified study of guided modes in plasma cladded step-index optical fiber

    NASA Astrophysics Data System (ADS)

    Mishra, A. K.; Singh, O. N.

    2015-06-01

    In this paper, the effect of plasma cladding on the modal dispersion characteristics of guided modes is explored. The dispersion relation of guided modes which is derived employing the usual boundary conditions, show a strong dependency on the operating frequency. The numerical aperture of plasma cladded light guide decreases on increasing the operating frequency which is quite contrary to conventional dielectric optical fibers. Our study further revealed that this decrease in numerical aperture is more prompt at lower frequency and hence, an unusual dispersion characteristic is displayed by hybrid modes. The transverse modes display the usual dispersion characteristics with only exceptions that these modes occur in pairs with approximately equal cutoff frequency. We hope that the study will be quite useful to investigate the behavior of high power laser beam propagating through air core or hollow fibers.

  15. Over 200 W average power tunable Raman amplifier based on fused silica step index fiber

    NASA Astrophysics Data System (ADS)

    Rekas, M.; Schmidt, O.; Zimer, H.; Schreiber, T.; Eberhardt, R.; Tünnermann, A.

    2012-06-01

    A high-power tunable Raman Amplifier is presented. The seed signal (varying from 1118 nm to 1130 nm in wavelength) was generated in a tunable Raman oscillator and fed into the Raman amplification stage. A conversion efficiency of up to 86 % was achieved and a maximum output power of over 200 W was measured. The Raman gain coefficient for the amplifier fiber was measured to be 0.76×10-14 m/W. Furthermore, the measured output power was compared with values obtained from simple mathematical model and a good agreement up to the highest output power of amplified signal was achieved.

  16. Fiber optic refractive index monitor

    DOEpatents

    Weiss, Jonathan David (Albuquerque, NM)

    2002-01-01

    A sensor for measuring the change in refractive index of a liquid uses the lowest critical angle of a normal fiber optic to achieve sensitivity when the index of the liquid is significantly less than the index of the fiber core. Another embodiment uses a liquid filled core to ensure that its index is approximately the same as the liquid being measured.

  17. Fiber optic phase stepping system for interferometry

    NASA Technical Reports Server (NTRS)

    Mercer, Carolyn R.; Beheim, Glenn

    1991-01-01

    A closed loop phase control system using an all-fiber optical configuration has been developed for use in phase-stepping interferometry. This system drives the relative phase of two interfering beams through a sequence of pi/2 rad increments so that the initial relative phase of these beams can be determined. This phase-stepping system uses optical fibers to provide spatially uniform phase steps from a flexible, easily aligned optical configuration. In addition, this system uses phase feedback to eliminate phase modulator errors and to compensate for phase drifts caused by environmental disturbances.

  18. Influence of measurement noise on the determination of the radial profile of the photoelastic coefficient in step-index optical fibers.

    PubMed

    Acheroy, Sophie; Merken, Patrick; Ottevaere, Heidi; Geernaert, Thomas; Thienpont, Hugo; Berghmans, Francis

    2013-12-10

    We discuss a measurement method that aims to determine the radial distribution of the photoelastic constant C in an optical fiber. This method uses the measurement of the retardance profile of a transversely illuminated fiber as a function of applied tensile load and requires the computation of the inverse Abel transform of this retardance profile. We focus on the influence of the measurement error on the obtained values for C. The results suggest that C may not be constant across the fiber and that the mean absolute value of C is slightly larger for glass fibers than for bulk fused silica. This can, for example, influence the accuracy with which one is able to predict the response of optical fiber sensors used for measuring mechanical loads. PMID:24513887

  19. Theory of biaxial graded-index optical fiber

    NASA Astrophysics Data System (ADS)

    Kawalko, Stephen F.

    1990-01-01

    A biaxial graded-index fiber with a homogeneous cladding is studied. Two methods, wave equation and matrix differential equation, of formulating the problem and their respective solutions are discussed. For the wave equation formulation of the problem it is shown that for the case of a diagonal permittivity tensor the longitudinal electric and magnetic fields satisfy a pair of coupled second-order differential equations. Also, a generalized dispersion relation is derived in terms of the solutions for the longitudinal electric and magnetic fields. For the case of a step-index fiber, either isotropic or uniaxial, these differential equations can be solved exactly in terms of Bessel functions. For the cases of an istropic graded-index and a uniaxial graded-index fiber, a solution using the Wentzel, Krammers and Brillouin (WKB) approximation technique is shown. Results for some particular permittivity profiles are presented. Also the WKB solutions is compared with the vector solution found by Kurtz and Streifer. For the matrix formulation it is shown that the tangential components of the electric and magnetic fields satisfy a system of four first-order differential equations which can be conveniently written in matrix form. For the special case of meridional modes, the system of equations splits into two systems of two equations. A general iterative technique, asymptotic partitioning of systems of equations, for solving systems of differential equations is presented. As a simple example, Bessel's differential equation is written in matrix form and is solved using this asymptotic technique. Low order solutions for particular examples of a biaxial and uniaxial graded-index fiber are presented. Finally numerical results obtained using the asymptotic technique are presented for particular examples of isotropic and uniaxial step-index fibers and isotropic, uniaxial and biaxial graded-index fibers.

  20. Pixelated high-index ring Bragg fibers.

    PubMed

    Baz, Assaad; Bouwmans, Géraud; Bigot, Laurent; Quiquempois, Yves

    2012-08-13

    A new type of Anti Resonant Reflecting Optical Waveguide (ARROW) fiber with a low refractive index contrast is reported. This waveguide is similar to a Bragg fiber for which the high index rings are replaced by discontinuous rings made of circular High Index Inclusions (HII). As compared to conventional Bragg fibers, such a new structure enables true Photonic BandGap (PBG) guidance and limits the number of cladding modes located within the high index regions, thus enhancing the guiding properties. A Mode Field Diameter (MFD) of 26 ?m is reported at a wavelength of 1400 nm. Single Mode (SM) behavior is also observed beyond 1400 nm for a 1 m-long fiber. PMID:23038519

  1. Speckle interferometry using fiber optic phase stepping

    NASA Technical Reports Server (NTRS)

    Mercer, Carolyn R.; Beheim, Glenn

    1989-01-01

    A system employing closed-loop phase-stepping is used to measure the out-of-plane deformation of a diffusely reflecting object. Optical fibers are used to provide reference and object beam illumination for a standard two-beam speckle interferometer, providing set-up flexibility and ease of alignment. Piezoelectric fiber-stretchers and a phase-measurement/servo system are used to provide highly accurate phase steps. Intensity data is captured with a charge-injection-device camera, and is converted into a phase map using a desktop computer. The closed-loop phase-stepping system provides 90 deg phase steps which are accurate to 0.02 deg, greatly improving this system relative to open-loop interferometers. The system is demonstrated on a speckle interferometer, measuring the rigid-body translation of a diffusely reflecting object with an accuracy + or - 10 deg, or roughly + or - 15 nanometers. This accuracy is achieved without the use of a pneumatically mounted optics table.

  2. Analysis and Design of Photonic Crystal Fibers Based on an Improved Effective-Index Method

    Microsoft Academic Search

    Hongbo Li; Arash Mafi; Axel Schülzgen; Li Li; Valery L. Temyanko; Nasser Peyghambarian; Jerome V. Moloney

    2007-01-01

    The modal characteristics of photonic crystal fibers (PCFs), with guiding cores consisting of one or seven missing airholes, are investigated with the finite element method and compared to those of step-index fibers (SIFs). To extend the applicability of the classical SIF theories to PCFs, the effective refractive index of photonic crystal cladding and the effective core radius of a PCF

  3. Fiber inline Michelson interferometer fabricated by one-step femtosecond laser micromachining for sensing applications

    NASA Astrophysics Data System (ADS)

    Yuan, Lei; Wu, Hongbin; Wang, Cong; Yu, Yingyu; Wang, Sumei; Xiao, Hai

    2013-12-01

    A fiber inline Michelson interferometer fiber optic sensor was presented for sensing applications, including high temperature performance and refractive index change. The sensor was fabricated using one-step femtosecond (fs) laser micromachining technique. A step structure at the tip of a single mode optical fiber was formed during the micromachining process. The device had a loss of 16 dB and an interference visibility exceeding 18 dB. The capability of this device for temperature sensing up to 1000 °C and refractive index sensing application in various concentrations of ethanol solution were all demonstrated.

  4. Surface plasmon resonance based fiber optic refractive index sensors

    NASA Astrophysics Data System (ADS)

    Hlubina, Petr; Kadulova, Miroslava; Ciprian, Dalibor

    2014-12-01

    Refractive index sensors based on surface plasmon resonance (SPR) in a thin metal film deposited on an unclad core of a multimode fiber are presented. The sensing element of the fiber optic SPR sensors is a bare core of a step-index optical fiber made of fused silica with a double-sided sputtered gold film. First, an in-line transmissionbased sensing scheme with the fiber optic SPR probe is used. Second, a reflection-based sensing scheme with a terminated fiber optic SPR probe is employed. The fiber optic SPR probes have different lengths and the thickness of the sputtered gold film is about 50 nm. Both sensing schemes utilize a wavelength interrogation method so that the refractive index of a liquid is sensed by measuring the position of the dip in the transmitted or reflected spectral intensity distribution. As an example, the aqueous solutions of ethanol with refractive indices in a range from 1.333 to 1.364 are measured. For the transmission-based sensing scheme a polarization-dependent response is revealed.

  5. Observation of images in graded-index multimode fiber 

    E-print Network

    Begum, Sultana

    1992-01-01

    of a multimode fiber. . . . . . . . . . 6 Optical spectrum of lasertmn laser Circuit diagram of temperature controller. . . . . Connection between temperature contmller and lasertron laser . Refractive index profile of a graded-index multimode...]. Reflection is affected by the lateral displacement of fiber 3 cores, core diameter, refractive-index difference, and refractive-index profile [2]. Under conditions that define multimode propagation in graded-index optical fiber, geometric optics and wave...

  6. Index guiding photonic liquid crystal fibers for application in fiber optic sensing setups

    Microsoft Academic Search

    Slawomir Ertman; Marzena M. Tefelska; Milosz S. Chychlowski; Dariusz Pysz; Ryszard Buczynski; Edward Nowinowski-Kruszelnicki; Roman Dabrowski; Tomasz R. Wolinski

    2011-01-01

    Photonic liquid crystal fibers (PLCFs) can be categorized in two principal groups: index guiding PLCFs and photonic bandgap PLCFs. In this paper we focus on index guiding PLCFs in which effective refractive index of the micro-structured cladding filled with liquid crystal is lower than refractive index of the fiber core. In such fibers broadband propagation of light is observed and

  7. Highly birefringent index-guiding photonic crystal fibers

    Microsoft Academic Search

    Theis P. Hansen; Jes Broeng; Stig E. B. Libori; Erik Knudsen; Anders Bjarklev; Jacob Riis Jensen; Harald Simonsen

    2001-01-01

    Photonic crystal fibers (PCFs) offer new possibilities of realizing highly birefringent fibers due to a higher intrinsic index contrast compared to conventional fibers. In this letter, we analyze theoretically the levels of birefringence that can be expected using relatively simple PCF designs. While extremely high degrees of birefringence may be obtained for the fibers, we demonstrate that careful design with

  8. Spatial Frequency Multiplexing of Fiber-Optic Interferometric Refractive Index Sensors Based on Graded-Index Multimode Fibers

    PubMed Central

    Liu, Li; Gong, Yuan; Wu, Yu; Zhao, Tian; Wu, Hui-Juan; Rao, Yun-Jiang

    2012-01-01

    Fiber-optic interferometric sensors based on graded-index multimode fibers have very high refractive-index sensitivity, as we previously demonstrated. In this paper, spatial-frequency multiplexing of this type of fiber-optic refractive index sensors is investigated. It is estimated that multiplexing of more than 10 such sensors is possible. In the multiplexing scheme, one of the sensors is used to investigate the refractive index and temperature responses. The fast Fourier transform (FFT) of the combined reflective spectra is analyzed. The intensity of the FFT spectra is linearly related with the refractive index and is not sensitive to the temperature.

  9. Recent developments in microstructured fiber Bragg grating refractive index sensors

    NASA Astrophysics Data System (ADS)

    Luo, Bin-Bin; Zhou, Xiao-jun; Zhao, Ming-fu; Zhong, Nianbing; Wang, Sao-fei

    2010-01-01

    Refractive index measurement by optical fiber sensors has proved to be effective in the research of biochemical and biomedical applications. The theoretical principles and technology underlying several microstructured fiber Bragg grating refractive index sensors developed over the past decade are classified and briefly summarized, and their future developments are considered.

  10. Fiber optic-based refractive index sensing at INESC Porto.

    PubMed

    Jorge, Pedro A S; Silva, Susana O; Gouveia, Carlos; Tafulo, Paula; Coelho, Luis; Caldas, Paulo; Viegas, Diana; Rego, Gaspar; Baptista, José M; Santos, José L; Frazão, Orlando

    2012-01-01

    A review of refractive index measurement based on different types of optical fiber sensor configurations and techniques is presented. It addresses the main developments in the area, with particular focus on results obtained at INESC Porto, Portugal. The optical fiber sensing structures studied include those based on Bragg and long period gratings, on micro-interferometers, on plasmonic effects in fibers and on multimode interference in a large spectrum of standard and microstructured optical fibers. PMID:22969405

  11. A step-defined sedentary lifestyle index: <5000 steps/day.

    PubMed

    Tudor-Locke, Catrine; Craig, Cora L; Thyfault, John P; Spence, John C

    2013-02-01

    Step counting (using pedometers or accelerometers) is widely accepted by researchers, practitioners, and the general public. Given the mounting evidence of the link between low steps/day and time spent in sedentary behaviours, how few steps/day some populations actually perform, and the growing interest in the potentially deleterious effects of excessive sedentary behaviours on health, an emerging question is "How many steps/day are too few?" This review examines the utility, appropriateness, and limitations of using a reoccurring candidate for a step-defined sedentary lifestyle index: <5000 steps/day. Adults taking <5000 steps/day are more likely to have a lower household income and be female, older, of African-American vs. European-American heritage, a current vs. never smoker, and (or) living with chronic disease and (or) disability. Little is known about how contextual factors (e.g., built environment) foster such low levels of step-defined physical activity. Unfavorable indicators of body composition and cardiometabolic risk have been consistently associated with taking <5000 steps/day. The acute transition (3-14 days) of healthy active young people from higher (>10?000) to lower (<5000 or as low as 1500) daily step counts induces reduced insulin sensitivity and glycemic control, increased adiposity, and other negative changes in health parameters. Although few alternative values have been considered, the continued use of <5000 steps/day as a step-defined sedentary lifestyle index for adults is appropriate for researchers and practitioners and for communicating with the general public. There is little evidence to advocate any specific value indicative of a step-defined sedentary lifestyle index in children and adolescents. PMID:23438219

  12. Self-similar propagation in a graded-index nonlinear-fiber amplifier with an external source

    SciTech Connect

    Raju, Thokala Soloman; Panigrahi, Prasanta K. [15647 Avenida Alcachofa, San Diego, California 92128 (United States); Indian Institute of Science Education and Research (IISER), Salt Lake, Kolkata 700106 (India)

    2010-04-15

    We present exact analytical solutions describing spatial bright, trigonometric, and kink-type of self-similar waves, as well as the trains of such waves to the nonlinear Schroedinger equation appropriately modified to model beam propagation in graded-index, nonlinear fiber amplifier with an external source. We show that this model is appropriate for the self-similar propagation in asymmetric twin-core fiber amplifier. The asymmetric twin-core fiber is composed of two adjoining, closely spaced, single mode fibers in which the active one is a graded-index nonlinear fiber and the passive one is a step-index fiber. We obtain these self-similar waves using a Moebius transformation. Our procedure is applicable both for self-focusing and self-defocusing Kerr nonlinearities.

  13. Theory of biaxial graded-index optical fiber

    NASA Technical Reports Server (NTRS)

    Kawalko, Stephen F.; Uslenghi, Piergiorgio L. E.

    1990-01-01

    The problem of wave propagation in a biaxial graded-index fiber with circular symmetry is considered. The problem is formulated in terms of four first-order differential equations for the tangential components of the electric and magnetic fields. A general solution method for solving systems of differential equations is presented. This solution method is then used to solve the system of equations for a particular example of a biaxial graded-index fiber. Numerical results for the propagation constant in the fiber are also given.

  14. Fiber-optic refractive index sensor based on surface plasmon resonance

    NASA Astrophysics Data System (ADS)

    Hlubina, Petr; Ciprian, Dalibor; Kadulova, Miroslava

    2015-01-01

    A fiber-optic refractive index sensor based on surface plasmon resonance (SPR) in a thin metal film deposited on an unclad core of a multimode fiber is presented. The sensing element of the SPR fiber-optic sensor is a bare core of a step-index optical fiber made of fused silica with a deposited gold film. First, a model of the SPR fiber-optic sensor based on the theory of attenuated total internal reflection is presented. The analysis is carried out in the frame of optics of multilayered media. The sensing scheme uses a wavelength interrogation method and the calculations are performed over a broad spectral range. Second, in a practical realization of the sensor with a double-sided sputtered gold film, a reflection-based sensing scheme to measure the refractive indices of liquids is considered. The refractive index of a liquid is sensed by measuring the position of the dip in the reflected spectral intensity distribution. As an example, the aqueous solutions of ethanol with refractive indices in a range from 1.333 to 1.364 are measured.

  15. Constant Refractive Index Multi-Core Fiber Laser

    SciTech Connect

    Beach, R J; Feit, M D; Brasure, L D; Payne, S A; Mead, R W; Hayden, J S; Krashkevich, D; Alunni, D A

    2002-03-18

    A scalable fiber laser approach is described based on phase-locking multiple gain cores in an antiguided structure. The waveguide is comprised of periodic sequences of gain- and no-gain-loaded segments having uniform index, within the cladding region. Initial experimental results are presented.

  16. Refractive index sensor based on a polymer fiber directional coupler for low index sensing.

    PubMed

    Lee, Kwang Jo; Liu, Xiaoqi; Vuillemin, Nelly; Lwin, Richard; Leon-Saval, Sergio G; Argyros, Alexander; Kuhlmey, Boris T

    2014-07-14

    We propose, numerically analyze and experimentally demonstrate a novel refractive index sensor specialized for low index sensing. The device is based on a directional coupler architecture implemented in a single microstructured polymer optical fiber incorporating two waveguides within it: a single-mode core and a satellite waveguide consisting of a hollow high-index ring. This hollow channel is filled with fluid and the refractive index of the fluid is detected through changes to the wavelength at which resonant coupling occurs between the two waveguides. The sensor design was optimized for both higher sensitivity and lower detection limit, with simulations and experiments demonstrating a sensitivity exceeding 1.4 × 10(3) nm per refractive index unit. Simulations indicate a detection limit of ~2 × 10(-6) refractive index units is achievable. We also numerically investigate the performance for refractive index changes localized at the surface of the holes, a case of particular importance for biosensing. PMID:25090565

  17. Sensitive liquid refractive index sensors using tapered optical fiber tips.

    PubMed

    Tai, Yi-Hsin; Wei, Pei-Kuen

    2010-04-01

    An optical fiber sensor based on the change of optical confinement in a subwavelength tip is presented. The optical spot is substantially increased when the environmental refractive index (RI) increases from 1.3 to 1.4. By measuring the intensity of low angular spectral components, an intensity sensitivity up to 8000% per RI unit is achieved. The fiber tip sensors take advantage of the small detection volume and real-time responses. We demonstrate the application of the nanofiber sensors for measuring concentrations of acids and evaporation rates of aqueous mixtures. PMID:20364178

  18. Control of Refractive Index Distribution for High-Bandwidth Graded Index Plastic Optical Fiber

    Microsoft Academic Search

    Makoto Asai; Kazuma Nehashi; Yasuhiro Koike

    2008-01-01

    The graded index plastic optical fiber (GI-POF) has been proposed as the transmission medium to realize high-speed information transmission. We have succeeded in fabricating a GI-POF by the coextrusion process, a method that allows continuous fabrication of GI-POF. Although it has been indicated that the refractive index distribution of GI-POF fabricated by this process is formed by Fick diffusion with

  19. Inline fiber interference-based refractive-index sensor

    NASA Astrophysics Data System (ADS)

    Gong, Zhenfeng; Zhang, Xinpu; Liu, Yun; Liu, Zigeng; Yu, Qingxu; Peng, Wei

    2014-11-01

    We report two fiber multiple-mode interferometers formed in photonic crystal fiber (PCF). The interference between the core and the cladding modes of a PCF is utilized. We use two methods to form a coupling point, and the cladding modes are excited from the fundamental core mode. One method is blowing compressed gas into the air holes and discharging at the coupling point; the air holes will expand due to gas expansion in the discharge process. Similarly, the other is discharging at the coupling point after the air is exhausted from the air holes, and the holes will contract during the process. By making another coupling point at a different location along the fiber, the proposed PCF interferometers are implemented. Experimental results show that the sensitivities of the two devices can achieve 1.54 and 1.45 nm for a 0.01 refractive index change.

  20. Phase-measuring fiber optic electronic speckle pattern interferometer: phase step calibration and phase drift minimization

    Microsoft Academic Search

    Charles Joenathan; Brij M. Khorana

    1992-01-01

    A phase-measuring fiber optic electronic speckle pattern interferometer (ESPI) was recently constructed and demonstrated. In this arrangement, phase stepping is introduced by stretching the fiber wrapped around a piezoelectric transducer. Calibration of the phase step is critical in phase measurement techniques for obtaining good phase plots. Methods used for calibrating the stretcher; are outlined and the drifts in the phase

  1. Organic Transistors on Fiber: A first step towards electronic textiles Josephine B. Lee and Vivek Subramanian

    E-print Network

    California at Irvine, University of

    Organic Transistors on Fiber: A first step towards electronic textiles Josephine B. Lee and Vivek a significant step towards the realization of electronics textiles. Fiber transistors exhibit mobilities of >10 with textile manufacturing, and is therefore a promising technology for scalable e-textile fabrication

  2. Interferometric fiber sensor using exposed core microstructured optical fiber for refractive index based biochemical sensing

    NASA Astrophysics Data System (ADS)

    Nguyen, Linh Viet; Warren-Smith, Stephen C.; Cooper, Alan; Monro, Tanya M.

    2014-05-01

    We proposed and experimentally demonstrated an in-fiber interferometric-type sensor by splicing an exposed core microstructured optical fiber (ECF) with lead-in and lead-out single mode fibers (SMFs) for refractive index-based biochemical sensing applications. Due to the multimode characteristic of the ECF, several modes can be excited at the lead-in splicing point and, after propagating through the ECF section, arrive at the lead-out splicing point with different phases forming a multi-arm interference pattern in the transmission spectrum of the device. Two dominant modes were found be consistently excited by maximizing the butt coupling between ECF and SMFs. The interference fringes shifts differently upon applying liquids of different refractive index on the exposed side of the ECF.

  3. Optically induced mode conversion in graded-index fibers using ultra-short laser pulses

    NASA Astrophysics Data System (ADS)

    Hellwig, Tim; Walbaum, Till; Fallnich, Carsten

    2013-09-01

    We propose the use of graded-index few-mode fibers for mode conversion by long-period gratings (LPG) transiently written by ultrashort laser pulses using the optical Kerr effect. The mode interaction is studied by numerically solving the multi-mode coupled nonlinear Schrödinger equations. We present highly efficient conversion of the LP01- into the LP11-mode preserving the pulse shape in contrast to previous results in step-index fibers. Furthermore, mode conversion using different wavelengths for inducing and probing the LPG is shown. Due to the flat phase-matching curve of the examined modes in the graded-index fiber, mode conversion can be observed for probe center wavelengths of 1,100 nm up to 1,800 nm with a write beam centered around 1,030 nm. Therefore, a complete separation of the probe from the write beam should be possible as well as the application of optically induced guided-mode conversion for all-optical modulation across a broad wavelength range.

  4. Refractive index profiling of a GRIN optical fiber using a modulated speckled sheet of light

    Microsoft Academic Search

    H. El-Ghandoor; E. Abd. El-Ghafar; R. Hassan

    1999-01-01

    A method for calculating the refractive index of GRIN optical fiber from its transverse interference pattern is presented.In this method the transverse interference fringe pattern through an optical fiber using a sheet of light is applied to get the refractive index profile of it. The optical fiber is not immersed in a matching liquid as used in different techniques [Barakat

  5. Photosensitivity in optical fibers: detection, characterization, and application to the fabrication of in-core fiber index gratings

    Microsoft Academic Search

    Bernard Malo; Francois Bilodeau; Derwyn C. Johnson; Iain M. Skinner; Kenneth O. Hill; Ted F. Morse; Arnd Kilian; Lawrence J. Reinhart; Kyunghwan Oh

    1991-01-01

    The irradiation of optical fibers by intense optical fields from visible or ultraviolet laser sources creates color centers within the glass fiber. Such laser light irradiation usually has the detrimental effect of increasing the transmission loss of the optical fibers particularly in the visible spectral region. A concomitant effect of the light irradiation is that the refractive index of the

  6. Reflectance Imaging by Graded-Index Short Multimode Fiber

    NASA Astrophysics Data System (ADS)

    Sato, Manabu; Kanno, Takahiro; Ishihara, Syoutarou; Suto, Hiroshi; Takahashi, Toshihiro; Nishidate, Izumi

    2013-05-01

    The imaging condition and magnifications were measured using a graded-index multimode fiber for optical communication with a diameter of 140 µm and a length of 5 mm. The field of view was about 80 µm and the test pattern of 4.38 µm period was recognized. Reducing the background noise with the polarizer reflectance images of the weed surface were measured to show the cell shapes. There are problems such as background, distortion, and nonuniformity of image quality; however, the feasibility for minimally invasive endoscope has been shown.

  7. Optimization of the Split-step Fourier Method in Modeling Optical Fiber Communications Systems

    E-print Network

    Maryland, Baltimore County, University of

    Optimization of the Split-step Fourier Method in Modeling Optical Fiber Communications Systems Oleg of different implementations of the split-step Fourier method for solving the nonlinear Schrödinger equation-order dispersion, the Raman 2 #12;effect, and filtering [2]. In this paper we focus on the split-step Fourier

  8. Interferometric fiber-optic gyroscope performance owing to temperature-induced index fluctuations in the fiber: effect on bias modulation

    NASA Astrophysics Data System (ADS)

    Knudsen, Sverre; Bløtekjær, Kjell

    1995-06-01

    An analysis of the noise floor owing to temperature-induced index fluctuations in the fiber of a dynamically biased interferometric fiber-optic gyroscope is presented. A comparison with shot noise indicates that, for a harmonic bias modulation, thermal noise in the fiber dominates for fiber lengths longer than \\similar 1 - 2km when practical source power levels are considered. The noise can be reduced or eliminated by the proper choice of modulation frequency or waveform.

  9. Two-dimensional scanning focused refractive-index microscopy and applications to refractive-index profiling of optical fibers

    NASA Astrophysics Data System (ADS)

    Wang, Xiaowan; Ye, Qing; Sun, Tengqian; Wang, Jin; Deng, Zhichao; Mei, Jianchun; Zhou, Wenyuan; Zhang, Chunping; Tian, Jianguo

    2015-01-01

    The refractive-index profile (RIP) of optical fibers is of fundamental significance in determining critical fiber properties. Here, we present the application of a two-dimensional (2-D) scanning focused refractive-index microscopy (SFRIM) to accurately obtain the 2-D RIP of a graded-index optical fiber. Some modifications are made to SFRIM for better 2-D measurement. Quantitative RIP of the fiber is obtained with derivative total reflection method. The refractive-index accuracy is 0.002. The measured result is in good agreement with theoretical expectation. This method is straightforward, simple, repeatable, and free from signal distortion. This technique is suitable for symmetric and asymmetric optical fibers. The results indicate that this technique can be applied to obtain the RIPs of a wide range of materials and has broad application prospect in many fields.

  10. Effect of dip in refractive index profile on fiber Raman gain amplifier performance

    NASA Astrophysics Data System (ADS)

    Pramanik, Sanchita; Sarkar, Somenath

    2014-10-01

    We have studied and reported the effect of practically possible linear dips in the inner core of a coaxial fiber Raman gain amplifier having step index inner and outer cores in the structure on the amplifier performance. In this work, we have used single pump wavelength of 1.465 ?m. A variation of dip depth beyond 0.25% of maximum refractive index and that of dip width beyond 25% of the inner core radius deteriorate the gain performance of characteristics of this amplifier significantly along with an appreciable shift of phase matching wavelength. Within these limits, the amplifier resembles closely the behavior of an ideal one. These prescribed limits of dip depth and dip width are also valid limits above which there will be valid ground in their effect to modulate Raman gain performance and dispersion. The present study should find wide attention of system designers.

  11. 1794 OPTICS LETTERS / Vol. 27, No. 20 / October 15, 2002 Gradient-index fiber-optic microprobes for minimally invasive

    E-print Network

    Schnitzer, Mark

    (LCI). The probes use novel fiber-optic gradient-index (GRIN) lenses fabricated by a recently developed the refractive-index gradient into GRIN fiber lenses using optical fiber production methods. Ge-doped GRIN1794 OPTICS LETTERS / Vol. 27, No. 20 / October 15, 2002 Gradient-index fiber-optic microprobes

  12. Characterization of fluids and fluid-fluid interaction by fiber optic refractive index sensor measurements

    NASA Astrophysics Data System (ADS)

    Schmidt-Hattenberger, C.; Weiner, M.; Liebscher, A.; Spangenberg, E.

    2009-04-01

    A fiber optic refractive index sensor is tested for continuous monitoring of fluid-fluid and fluid-gas interactions within the frame of laboratory investigations of CO2 storage, monitoring and safety technology research (COSMOS project, "Geotechnologien" program). The sensor bases on a Fabry-Perot white light interferometer technique, where the refractive index (RI) of the solution under investigation is measured by variation of the liquid-filled Fabry-Perot optical cavity length. Such sensor system is typically used for measuring and controlling oil composition and also fluid quality. The aim of this study is to test the application of the fiber optic refractive index sensor for monitoring the CO2 dissolution in formation fluids (brine, oil, gas) of CO2 storage sites. Monitoring and knowledge of quantity and especially rate of CO2 dissolution in the formation fluid is important for any assessment of long-term risks of CO2 storage sites. It is also a prerequisite for any precise reservoir modelling. As a first step we performed laboratory experiments in standard autoclaves on a variety of different fluids and fluid mixtures (technical alcohols, pure water, CO2, synthetic brines, natural formation brine from the Ketzin test site). The RI measurements are partly combined with default electrical conductivity and sonic velocity measurements. The fiber optic refractive index sensor system allows for RI measurements within the range 1.0000 to 1.7000 RI with a resolution of approximately 0.0001 RI. For simple binary fluid mixtures first results indicate linear relationships between refractive indices and fluid composition. Within the pressure range investigated (up to 60 bar) the data suggest only minor changes of RI with pressure. Further, planned experiments will focus on the determination of i) the temperature dependency of RI, ii) the combined effects of pressure and temperature on RI, and finally iii) the kinetics of CO2 dissolution in realistic formation fluids.

  13. PHOSPHITE STABILIZATION EFFECTS ON TWO-STEP MELT-SPUN FIBERS OF POLYLACTIDE. (R826733)

    EPA Science Inventory

    The effects of molecular weight stabilization on mechanical properties of polylactide (PLA) fibers are investigated. The textile-grade PLA contains a 98:02 ratio of L:D stereocenters and fibers are produced by the two step method, involving a primary quench and cold drawing. M...

  14. Split Step Fourier Method Based Pulse Propagation Model for Nonlinear Fiber Optics

    Microsoft Academic Search

    M. Y. Hamza; S. Tariq

    2007-01-01

    A pulse propagation model is essential to investigate various effects in nonlinear optical fiber communications. Split step Fourier method (SSFM) is an efficient technique to implement nonlinear Schrodinger equation (NLSE) which describes pulse propagation phenomenon in optical fiber. We report some simulation results obtained using our developed model based on SSFM. Our results are in well accordance with the standard

  15. Split-step spline method for modeling optical fiber communications systems

    Microsoft Academic Search

    Malin Premaratne

    2004-01-01

    Operator splitting techniques such as the split-step Fourier method or the split-step wavelet method have been successfully used for numerical simulation of uniformly time-sampled pulses along nonlinear optical fibers. In this letter, we extend the operator splitting technique to derive a novel numerical algorithm based on cubic B-splines for simulating propagation of nonuniformly sampled optical pulses along nonlinear optical fiber.

  16. Towards Silk Fiber Optics: Refractive Index Characterization, Fiber Spinning, and Spinneret Analysis

    NASA Astrophysics Data System (ADS)

    Spitzberg, Joshua David

    Of the many biologically derived materials, whose historical record of use by humans underscores an ex-vivo utility, silk is interesting for it's contemporary repurposing from textile to biocompatible substrate. And while even within this category silk is one of several materials studied for novel repurposing, it has the unique character of being evolutionarily developed specifically for fiber spinning in vivo. The work discussed here is inspired by taking what nature has given, to explore the in vitro spinning of silk towards biocompatible fiber optics applications. A common formulation of silk used in biomedical studies for re-forming it into the various structures begins with the silkworm cocoon, which is degummed and dissolved into an aqueous solution of its miscible protein, fibroin, and post-treated to fabricate solid structures. In the first aim, the optical refractive index (RI) of various post-treatment methods is discussed towards determining RI design techniques. The methods considered in this work for re-forming a solid fiber from the reconstituted silk fibroin (RSF) solution borrow from the industrial techniques of gel spinning, and dry-spinning. In the second aim, methods are applied to RSF and quality of the spun fibers discussed. A feature common to spinning techniques is passing the (silk) material through a spinneret of specific shape. In the third aim, fluid flow through a simplified native silkworm spinneret is modeled towards bio-inspired lessons in design. In chapter 1 the history, reconstitution, are discussed towards understanding the fabrication of several optical device examples. Chapter 2 then prefaces the experiments and measurements in fiber optics by reviewing electromagnetic theory of waveguide function, and loss factors, to be considered in actual device fabrication. Chapter 3 presents results and discussion for the first aim, understanding design principles for the refractive index of RSF. From this point, industrial fiber-spinning approaches are reviewed from a theoretical and methodological perspective in chapter 4. Thus, chapter 5 presents results for the second aim, efforts to apply these techniques using RSF. Chapter 6 discusses the third aim, understanding the design of the silkworm spinneret by an idealized model of natural and reconstituted silk fibroin flow. While the ultimate goal of a structurally and optically smooth and uniform fiber remains elusive, this work serves as a guide for future efforts.

  17. Fundamental-mode cutoff in a photonic crystal fiber with a depressed-index core.

    PubMed

    Mangan, B J; Arriaga, J; Birks, T A; Knight, J C; Russell, P S

    2001-10-01

    We report a photonic crystal fiber with a depressed-index core doped with fluorine. The effective index of the cladding matches that of the core at an antiguiding wavelength, below which the fiber does not guide light at all. PMID:18049637

  18. Optical properties of side-polished polarization maintaining fiber coupled with a high index planar waveguide

    Microsoft Academic Search

    Kwang Taek Kim; Dae Sung Yoon; Gyeong-il Kwoen

    2004-01-01

    We have investigated the behavior of an asymmetric directional coupler made of a side-polished polarization maintaining (PM) fiber covered with a high index planar waveguide (PWG). The effects of the modal birefringence of the side-polished PM fiber, the structural parameters of PWG and the deformation of the PM fiber on the transmission characteristics of the coupler has been measured and

  19. Extrinsic fiber-optic Fabry-Perot interferometer sensor for refractive index measurement of optical glass

    SciTech Connect

    Chen Jihuan; Zhao Jiarong; Huang Xuguang; Huang Zhenjian

    2010-10-10

    A simple fiber-optic sensor based on Fabry-Perot interference for refractive index measurement of optical glass is investigated both theoretically and experimentally. A broadband light source is coupled into an extrinsic fiber Fabry-Perot cavity formed by the surfaces of a sensing fiber end and the measured sample. The interference signals from the cavity are reflected back into the same fiber. The refractive index of the sample can be obtained by measuring the contrast of the interference fringes. The experimental data meet with the theoretical values very well. The proposed technique is a new method for glass refractive index measurement with a simple, solid, and compact structure.

  20. Characterization of the stress and refractive-index distributions in optical fibers and fiber-based devices

    NASA Astrophysics Data System (ADS)

    Hebenstreit, Florian

    2011-07-01

    Optical fiber technology continues to advance rapidly as a result of the increasing demands on communication systems and the expanding use of fiber-based sensing. New optical fiber types and fiber-based communications components are required to permit higher data rates, an increased number of channels, and more flexible installation requirements. Fiber-based sensors are continually being developed for a broad range of sensing applications, including environmental, medical, structural, industrial, and military. As optical fibers and fiber-based devices continue to advance, the need to understand their fundamental physical properties increases. The residual-stress distribution (RSD) and the refractive-index distribution (RID) play fundamental roles in the operation and performance of optical fibers. Custom RIDs are used to tailor the transmission properties of fibers used for long-distance transmission and to enable fiber-based devices such as long-period fiber gratings (LPFGs). The introduction and modification of RSDs enable specialty fibers, such as polarization-maintaining fiber, and contribute to the operation of fiber-based devices. Furthermore, the RSD and the RID are inherently linked through the photoelastic effect. Therefore, both the RSD and the RID need to be characterized because these fundamental properties are coupled and affect the fabrication, operation, and performance of fibers and fiber-based devices. To characterize effectively the physical properties of optical fibers, the RSD and the RID must be measured without perturbing or destroying the optical fiber. Furthermore, the techniques used must not be limited in detecting small variations and asymmetries in all directions through the fiber. Finally, the RSD and the RID must be characterized concurrently without moving the fiber to enable the analysis of the relationship between the RSD and the RID. Although many techniques exist for characterizing the residual stress and the refractive index in optical fibers, there is no existing methodology that meets all of these requirements. Therefore, the primary objective of the research presented in this thesis was to provide a methodology that is capable of characterizing concurrently the three-dimensional RSD and RID in optical fibers and fiber-based devices. This research represents a detailed study of the requirements for characterizing optical fibers and how these requirements are met through appropriate data analysis and experimental apparatus design and implementation. To validate the developed methodology, the secondary objective of this research was to characterize both unperturbed and modified optical fibers. The RSD and the RID were measured in a standard telecommunications-grade optical fiber, Corning SMF-28. The effects of cleaving this fiber were also analyzed and the longitudinal variations that result from cleaving were explored for the first time. The fabrication of carbon-dioxide-laser-induced (CO2 -laser-induced) LPFGs was also examined. These devices provide many of the functionalities required for fiber-based communications components as well as fiber-based sensors, and they offer relaxed fabrication requirements when compared to LPFGs fabricated by other methods. The developed methodology was used to perform the first measurements of the changes that occur in the RSD and the RID during LPFG fabrication. The analysis of these measurements ties together many of the existing theories of CO2-laser-induced LPFG fabrication to present a more coherent understanding of the processes that occur. In addition, new evidence provides detailed information on the functional form of the RSD and the RID in LPFGs. This information is crucial for the modeling of LPFG behavior, for the design of LPFGs for specific applications, for the tailoring of fabrication parameters to meet design requirements, and for understanding the limitations of LPFG fabrication in commercial optical fibers. Future areas of research concerning the improvement of the developed methodology, the need to characterize other fibers and f

  1. Evaluation of modal noise in graded-index silica and plastic optical fiber links for radio over multimode fiber systems.

    PubMed

    Matsuura, Motoharu; Furukawa, Rei; Matsumoto, Yuki; Inoue, Azusa; Koike, Yasuhiro

    2014-03-24

    We have evaluated and compared modal noise induced in a graded-index silica multimode fiber (GI-MMF) link and a graded-index plastic optical fiber (GI-POF) link with the misaligned fiber connections. In radio over fiber (RoF) systems using these optical fibers, modal noise appears as unwanted amplitude modulation in the received signal, and results in degradation of the RoF transmission performance. In this work, we have evaluated the modal noise induced in GI-MMFs and GI-POFs with its same core diameter of 50 ?m. Our results show that GI-POFs have an inherently higher tolerance to misaligned connection and less modal noise than GI-MMFs in terms of both the error-vector magnitude and the speckle pattern of the transmitted signals. PMID:24664004

  2. Refractive index insensitive temperature sensor based on coaxial waveguide fiber modal interferometer

    NASA Astrophysics Data System (ADS)

    Zhou, Ai; Xu, Quan; Zheng, Tuo; Yang, Jun; Yang, Yuanyuan; Yuan, Libo

    2013-09-01

    A refractive index insensitive temperature sensor based on coaxial dual-waveguide optical fiber was proposed and demonstrated. The coaxial fiber contains a central core along the fiber axis and an annular core between the inner/outer claddings. By inserting the coaxial fiber in between two single mode fibers through core-offset splicing, cladding modes are excited at the splice point and therefore a modal Mach-Zehnder interferometer is achieved. The effective refractive index of the inner cladding mode is independent of the external refractive index due to the existence of the annular core. Owing to the large thermo-optic coefficient difference between the coaxial fiber's core and cladding, the modal interferometer has high temperature sensitivity. Such an interferometer is extremely suitable for temperature measurement in wet or liquid environment.

  3. High power fiber delivery for laser ignition applications.

    PubMed

    Yalin, Azer P

    2013-11-01

    The present contribution provides a concise review of high power fiber delivery research for laser ignition applications. The fiber delivery requirements are discussed in terms of exit energy, intensity, and beam quality. Past research using hollow core fibers, solid step-index fibers, and photonic crystal and bandgap fibers is summarized. Recent demonstrations of spark delivery using large clad step-index fibers and Kagome photonic bandgap fibers are highlighted. PMID:24514929

  4. Phosphite stabilization effects on two-step melt-spun fibers of polylactide

    Microsoft Academic Search

    John A Cicero; John R Dorgan; Steven F Dec; Daniel M Knauss

    2002-01-01

    The effects of molecular weight stabilization on mechanical properties of polylactide (PLA) fibers are investigated. The textile-grade PLA contains a 98:02 ratio of L:D stereocenters and fibers are produced by the two step method, involving a primary quench and cold drawing. Molecular weight loss, which is approximately 30% for unstabilized PLA, can be eliminated by the addition of small amounts

  5. Influence of the refractive index of liquids in the speckle pattern of multimode fibers

    NASA Astrophysics Data System (ADS)

    Galindez, Carlos; Lomer, Mauro; Rodriguez-Cobo, Luis; Lopez-Higuera, J. M.

    2012-10-01

    The distribution of the intensity of each speckle depends on the relative phases of modes in the multimode fiber, so they are extremely sensitive to external perturbations of the fiber. These perturbations can locally appear in the fiber without disrupting the entire optical assembly. If the refractive index of the outside medium of the fiber is changed, it can cause variations in the speckle pattern at the fiber output. Thus, by changing the refractive index of the outside medium the speckle pattern at the output fiber varies and its influence can be observed. In this paper we demonstrate the influence of the refractive index of liquids in the speckle pattern obtained by a multimode fiber. In order to obtain greater sensitivity of the experimental measurement, the fiber is bent in a U-shape and immersed in a liquid. The core and cladding are 240 microns and 250 microns, respectively. The intensity speckle field is then captured by a CCD camera in digital image format and processed by the computer with a Matlab program. The portion of fiber exposed to the disturbance of the liquid is located 2 meters before the exit of the fiber. The portion of the fiber in contact with the liquid is curved with a radius of 2 mm.

  6. Time efficiency of the electric tuning of index-guiding photonic liquid crystal fiber

    NASA Astrophysics Data System (ADS)

    Siarkowska, Agata; Ertman, Slawomir; Wolinski, Tomasz R.

    2012-05-01

    Properties of photonic crystal fibers (PCFs) filled with nematic liquid crystals (LC) can be easily tuned by using an external electric field. In this work we focus on electrical tuning of index-guiding photonic liquid crystal fibers (PLCF) based on fibers made from multi-component glasses with an enhanced value of the refractive index. The impact of an electric field on light propagation in index guiding PLCFs has been carefully studied and the effective tuning of phase birefringence has been observed experimentally. The dependence of time response on the modulation level will be presented. In the end we will show polarization controller made with two pair of electrodes.

  7. Multigigabit\\/s perfluorinated graded-index plastic-optical-fiber data links with butt-coupled single-mode InGaAs VCSEL

    Microsoft Academic Search

    Felix Mederer; Roland Jaeger; Peter Schnitzer; Heiko J. Unold; Max Kicherer; Karl J. Ebeling; Masaki Naritomi; Ryouta Yoshida

    1999-01-01

    Vertical-cavity surface-emitting lasers (VCSELs) with emission wavelengths in the range from 850 nm to 950 nm are highly attractive light sources for low-cost, high-speed data transmission over several hundred meters of perfluorinated graded-index plastic-optical fibers (GI- POFs). Multi-Gigabit\\/s data transmission over common PMA- based step-index POFs is generally limited to several meters predominantly due to dispersion. Here, we demonstrate 3

  8. High-index-core Bragg fibers: dispersion Juan A. Monsoriu

    E-print Network

    Fernández de Córdoba, Pedro

    in conventional photonic crystal fibers, surrounded by a multilayered cladding, which is formed by a set.V. Andrés, "Donor and acceptor guided modes in photonic crystal fibers," Opt. Lett. 25, 1328-1330 (2000). 3 crystal fibers," Opt. Lett. 25, pp. 790-792 (2000). 10. W.H. Reeves, J.C. Knight, P.St.J. Russell, and P

  9. Two-dimensional refractive index and stresses profiles of a homogenous bent optical fiber.

    PubMed

    Ramadan, W A; Wahba, H H; Shams El-Din, M A

    2014-11-01

    We present a significant contribution to the theory of determining the refractive index profile of a bent homogenous optical fiber. In this theory we consider two different processes controlling the index profile variations. The first is the linear index variation due to stress along the bent radius, and the second is the release of this stress on the fiber surface. This release process is considered to have radial dependence on the fiber radius. These considerations enable us to construct the index profile in two dimensions normal to the optical axis, considering the refraction of light rays traversing the fiber. This theory is applied to optical homogenous bent fiber with two bending radii when they are located orthogonal to the light path of the object arm in the holographic setup (like the Mach-Zehnder interferometer). Digital holographic phase shifting interferometry is employed in this study. The recorded phase shifted holograms have been combined, reconstructed, and processed to extract the phase map of the bent optical fiber. A comparison between the extracted optical phase differences and the calculated one indicates that the refractive index profile variation should include the above mentioned two processes, which are considered as a response for stress distribution across the fiber's cross section. The experimentally obtained refractive index profiles provide the stress induced birefringence profile. Thus we are able to present a realistic induced stress profile due to bending. PMID:25402912

  10. One-step Tape Casting of Composites via Slurry on Fiber

    NASA Technical Reports Server (NTRS)

    deGroh, Henry C., III

    2001-01-01

    A process by which metal matrix composites can be made was presented. The process involves putting a powder slurry on fibers to make a precursor green tape. These green tapes are cut, stacked and hot pressed to form the fully dense composite. A computer program was presented which enables complete quantification and control of the process. Once some easily obtained properties of the slurry and its behavior are determined (such as the shrinkage from the wet to green state, and the density of the green tape) modification of the fiber spacing and blade height give the maker precise control of fiber volume fraction, and fiber architecture in the composite. The process was shown to be accurate and flexible through the production of a wide variety of volume fraction fiber composites made from a wide variety of fibers and powders. The most time consuming step of the tape casting process (other than hot pressing) was winding the fiber on the drum. The tape casting techniques developed resulted in high quality metal matrix composites, with ultimate tensile strength in the range of 215 ksi (1477 MPa), a strain at failure of 1.15 percent, and in fatigue at room temperature 0 to 120 ksi, n = 0.3 Hz, a 4-ply Ti-24Al-11Nb/SCS-6, 32 vol% fiber tape cast composite lasted 202,205 cycles with a maximum strain on the 100th cycle of 0.43 percent.

  11. Nondestructive determination of refractive index profile of an optical fiber: backward light scattering method.

    PubMed

    Saekeang, C; Chu, P L

    1979-04-01

    A new nondestructive technique is presented for determining the refractive index profile of an optical fiber from its backscattered pattern arising from a normally incident laser beam to the fiber axis. The proposed method requires no sample preparation or index matching liquid. The principle of the method is to construct a deflection function from the measured pattern. The index profile can then be determined by the inversion of an Abel integral equation. Good agreement is obtained between the index profile determined by this technique and that measured by the near-field scanning technique. PMID:20208886

  12. A Refractive Index Sensor Based on the Resonant Coupling to Cladding Modes in a Fiber Loop

    PubMed Central

    Reyes, Mauricio; Monzón-Hernández, David; Martínez-Ríos, Alejandro; Silvestre, Enrique; Díez, Antonio; Cruz, José Luis; Andrés, Miguel V.

    2013-01-01

    We report an easy-to-build, compact, and low-cost optical fiber refractive index sensor. It consists of a single fiber loop whose transmission spectra exhibit a series of notches produced by the resonant coupling between the fundamental mode and the cladding modes in a uniformly bent fiber. The wavelength of the notches, distributed in a wavelength span from 1,400 to 1,700 nm, can be tuned by adjusting the diameter of the fiber loop and are sensitive to refractive index changes of the external medium. Sensitivities of 170 and 800 nm per refractive index unit for water solutions and for the refractive index interval 1.40–1.442, respectively, are demonstrated. We estimate a long range resolution of 3 × 10?4 and a short range resolution of 2 × 10?5 for water solutions. PMID:23979478

  13. Characterization of fluids and fluid-fluid interaction by fiber optic refractive index sensor measurements

    Microsoft Academic Search

    C. Schmidt-Hattenberger; M. Weiner; A. Liebscher; E. Spangenberg

    2009-01-01

    A fiber optic refractive index sensor is tested for continuous monitoring of fluid-fluid and fluid-gas interactions within the frame of laboratory investigations of CO2 storage, monitoring and safety technology research (COSMOS project, \\

  14. FRPRCS-9 Sydney, Australia Monday 13 Wednesday 15 July 2009 STEPPED ISOSTRESS METHOD FOR ARAMID FIBERS

    E-print Network

    Burgoyne, Chris

    FIBERS Ioannis P. GIANNOPOULOS 1 Chris J. BURGOYNE 2 1 PhD student, Department of Engineering, University Keywords: kevlar 49, technora, stepped isostress method, stress-rupture, accelerated testing, activation concentration, strain or stress. Among them, temperature and stress are the two most important factors for load

  15. Study on a new split-step Fourier algorithm for optical fiber transmission systems simulations

    Microsoft Academic Search

    T. T. Meirelles; A. A. Rieznik; H. L. Fragnito

    2005-01-01

    Recently we presented a new split-step Fourier algorithm to the simulation of optical-fiber transmission systems. To check it, we show here its efficiency to model a two first-order soliton collision, which is a situation of practical interest because of its sensitivity to numerical errors.

  16. Optical fiber refractive index sensor with reduced thermal sensitivity based on Superimposed Long-Period Gratings

    NASA Astrophysics Data System (ADS)

    Silva, G. E.; Caldas, P.; Santos, J. C.; Santos, J. L.

    2014-05-01

    In this paper, we report the development of a reduced temperature sensitivity optical fiber sensor for refractive index measurement based on Superimposed Long-Period Gratings (SLPG) inscribed by the electric arc technique in standard fiber. The reduced sensitivity to temperature is achieved by calculation of the difference between resonance wavelengths of two guided cladding modes.

  17. Sensors and Actuators B 123 (2007) 594605 Fiber optic sensing of liquid refractive index

    E-print Network

    2007-01-01

    with adsorbent material deposited by Sol­gel tech- nique to make it a sensor of chemicals that get adsorbed is immersed, to a high degree of precision and over a wide range of refractive index. The slope of sensor as highly sensitive RI sensing devices. Tapering of fiber and stripping of the fiber cladding have been used

  18. Interactions between fluid and fibers in a turbulent backward-facing step flow

    NASA Astrophysics Data System (ADS)

    Capone, Alessandro; Romano, Giovanni Paolo

    2015-05-01

    In this work, a turbulent backward-facing step flow at Reynolds number ReH = 17 520, laden with rod-like particles, is investigated by means of particle image velocimetry. Particle loadings tested are within 0.02% and 0.05% volume fractions; thus, the suspensions may be considered as dilute. The high spatial resolution allows the identification of fiber orientation within the flow, so that mutual interactions between phases can be investigated by considering flow modifications and phenomena related to preferential concentration and orientation of fibers. Fibers' concentration data show a moderate trend to accumulate at the channel centreline, whereas orientation data display a strong preferential orientation of fibers. Specifically, the local fibers' orientation is correlated to the flow field in terms of mean flow direction and plane of maximum shear. The occurrence of a symmetrical orientation profile with respect to the channel centre-line is reported as well as the tendency to recover such profile downstream of the step.

  19. Power attenuation in bent multimode step-index slab and fibre waveguides

    Microsoft Academic Search

    J. D. Love; C. Winkler

    1978-01-01

    A situation is analyzed in which a diffuse or Lambertian source illuminates the entire endface of an ideal multimode step-index waveguide. The guide is straight for a distance 'd' beyond which a bend of uniform radius is introduced. It is assumed that d is sufficiently large that all leaky rays have lost their power and essentially only bound rays remain

  20. Direct method of determination of the equivalent refractive index profile of the multimode optical fiber by measured impulse responses due to scanning output fiber end

    NASA Astrophysics Data System (ADS)

    Burdin, Vladimir A.; Bourdine, Anton V.; Praporshchikov, Denis E.

    2015-03-01

    This paper demonstrates the possibility of determining the equivalent, in terms of the coincidence of differential mode delay diagram, refractive index profile of the multimode optical fiber by direct method and responses to pulse action, which are measured at the output through single-mode optical fiber. As an example, by using the measured data of the refractive index profile of the sample of multimode optical fiber and based on Gaussian approximation model impulse responses at the output of a short length single mode fiber, which was jointed with multimode fiber, were calculated. Multimode and single mode fibers were jointed with axial misalignment. Responses to impulse action were calculated for several values of axial misalignment of single-mode and multimode fiber. From the responses by the direct method the equivalent refractive index profile was determined. Comparison of the results of calculations of the differential-mode delay diagram for the investigated and the equivalent refractive index profiles showed their good agreement.

  1. High power fiber optic laser beam delivery

    Microsoft Academic Search

    K. H. Leong; B. V. Hunter

    1996-01-01

    Fiber-optic beam delivery is commonly used on industrial laser systems. This article examines the conditions for the optimal propagation of high power beams through optical fibers. Beam quality effects by step and gradient index fibers of different lengths are considered. The differences between the diverging beam from a fiber and the beam at focus and on the fiber face are

  2. Spectral and spatial characterization of perfluorinated graded-index polymer optical fibers for the distribution of optical wireless communication cells.

    PubMed

    Hajjar, Hani Al; Montero, David S; Lallana, Pedro C; Vázquez, Carmen; Fracasso, Bruno

    2015-02-10

    In this paper, the characterization of a perfluorinated graded-index polymer optical fiber (PF-GIPOF) for a high-bitrate indoor optical wireless system is reported. PF-GIPOF is used here to interconnect different optical wireless access points that distribute optical free-space high-bitrate wireless communication cells. The PF-GIPOF channel is first studied in terms of transmission attenuation and frequency response and, in a second step, the spatial power profile distribution at the fiber output is analyzed. Both characterizations are performed under varying restricted mode launch conditions, enabling us to assess the transmission channel performance subject to potential connectorization errors within an environment where the end users may intervene by themselves on the home network infrastructure. PMID:25968032

  3. An automatic step adjustment method for average power analysis technique used in fiber amplifiers

    NASA Astrophysics Data System (ADS)

    Liu, Xue-Ming

    2006-04-01

    An automatic step adjustment (ASA) method for average power analysis (APA) technique used in fiber amplifiers is proposed in this paper for the first time. In comparison with the traditional APA technique, the proposed method has suggested two unique merits such as a higher order accuracy and an ASA mechanism, so that it can significantly shorten the computing time and improve the solution accuracy. A test example demonstrates that, by comparing to the APA technique, the proposed method increases the computing speed by more than a hundredfold under the same errors. By computing the model equations of erbium-doped fiber amplifiers, the numerical results show that our method can improve the solution accuracy by over two orders of magnitude at the same amplifying section number. The proposed method has the capacity to rapidly and effectively compute the model equations of fiber Raman amplifiers and semiconductor lasers.

  4. An integral split-step fourier method for digital back propagation to compensate fiber nonlinearity

    NASA Astrophysics Data System (ADS)

    Yang, Jie; Yu, Song; Li, Minliang; Chen, Zhixiao; Han, Yi; Gu, Wanyi

    2014-02-01

    In optical fiber transmission systems, the split-step Fourier method (SSFM) has been widely used in digital back propagation (DBP) to compensate fiber nonlinearity. In this paper, by using the Lagrange's Integral Mean Value Theorem (LIMVT), we derive an analytical expression to calculate the optimal value of the nonlinearity calculation position (NLCP) for different systems and we propose an integral SSFM (I-SSFM) based on the expression. The I-SSFM can be performed more accurately and efficiently without parameter optimization. Simulations of various transmission links show that the I-SSFM outperforms the conventional asymmetric SSFM (A-SSFM) and the symmetric SSFM (S-SSFM) significantly, especially when we employ less amount of steps to ensure computation efficiency. The computation effort of the I-SSFM reaches as low as 50% of that of the S-SSFM.

  5. Photonic crystal fiber devices

    Microsoft Academic Search

    Tim A. Birks; George Kakarantzas; Philip S. Russell; Dominic F. Murphy

    2003-01-01

    Photonic crystal fibers (PCFs) have been receiving increasing attention over the past few years. They are single material fibers that use an array of air holes in the cladding to confine light to a core, instead of the more usual refractive index step within the solid material of a conventional fiber. As PCFs become more well-understood mainstream structures, the need

  6. Reflection based Extraordinary Optical Transmission Fiber Optic Probe for Refractive Index Sensing.

    PubMed

    Lan, Xinwei; Cheng, Baokai; Yang, Qingbo; Huang, Jie; Wang, Hanzheng; Ma, Yinfa; Shi, Honglan; Xiao, Hai

    2014-03-31

    Fiber optic probes for chemical sensing based on the extraordinary optical transmission (EOT) phenomenon are designed and fabricated by perforating subwavelength hole arrays on the gold film coated optical fiber endface. The device exhibits a red shift in response to the surrounding refractive index increases with high sensitivity, enabling a reflection-based refractive index sensor with a compact and simple configuration. By choosing the period of hole arrays, the sensor can be designed to operate in the near infrared telecommunication wavelength range, where the abundant source and detectors are available for easy instrumentation. The new sensor probe is demonstrated for refractive index measurement using refractive index matching fluids. The sensitivity reaches 573 nm/RIU in the 1.333~1.430 refractive index range. PMID:24574579

  7. Fiber inline Michelson interferometer fabricated by CO2 laser irradiation for refractive index sensing

    NASA Astrophysics Data System (ADS)

    Wu, Hongbin; Yuan, Lei; Zhao, Longjiang; Cao, Zhitao; Wang, Peng

    2014-03-01

    A compact Michelson interferometer (MI) in a single-mode fiber (SMF) is successfully formed by CO2 laser irradiation to measure refractive index (RI) values. The fiber inline MI mainly consists of two parts: one is the waist region in fiber formed by CO2 laser irradiation and the other one is the fiber tip end facet with pure gold sputter coating. Based on the MI theory, the interference signal is generate between the core mode and the cladding mode excited by the core mode at the waist region. Reflective spectra at two different interference lengths of 5mm and 15mm are given and the calculated lengths based on theory are well verified. After the measurements of matching liquids with seven different refractive indices, the RI sensitivity of the MI sample is tested of -197.3+/-19.1nm/RIU (refractive index unit), which suggests well potential application in RI sensing.

  8. Prediction of Macrobending and Splice Losses for Photonic Crystal Fibers based on the Effective Index Method

    E-print Network

    G. S. Kliros; J. Konstantinidis; C. Thraskias

    2007-05-20

    An index-guiding photonic crystal fiber (PCF) with an array of air holes surrounding the silica core region has special characteristics compared to conventional single-mode fibers (SMFs). Using the effective index method and the Gaussian beam propagation theory, the macro-bending and splice losses for PCFs are investigated. The wavelength dependence of the cladding index of the PCF has been taken properly into account. We obtain the effective spot size for different configurations of PCFs, which is used for computing the splice losses. The Gaussian approximation for the fundamental modal field leads to simple closed-form expressions for the splice losses produced by transverse, longitudinal and angular offsets. Calculations of macro-bending losses are based on antenna theory for bend standard fibers.

  9. Higher-Order Modal Dispersion in Graded-Index Multimode Fiber

    Microsoft Academic Search

    Mahdieh B. Shemirani; Joseph M. Kahn

    2009-01-01

    Previously, we proposed a field-coupling model for propagation in graded-index multimode fiber (MMF), analogous to the principal states model for polarization-mode dispersion (PMD) in single-mode fiber. That model was based on the concept of first-order principal modes, which have well-defined group delays that depend on the strength of the mode coupling. That first-order model predicts a linear relationship between the

  10. A Multi-D-Shaped Optical Fiber for Refractive Index Sensing

    PubMed Central

    Chen, Chien-Hsing; Tsao, Tzu-Chein; Tang, Jaw-Luen; Wu, Wei-Te

    2010-01-01

    A novel class of multi-D-shaped optical fiber suited for refractive index measurements is presented. The multi-D-shaped optical fiber was constructed by forming several D-sections in a multimode optical fiber at localized regions with femtosecond laser pulses. The total number of D-shaped zones fabricated could range from three to seven. Each D-shaped zone covered a sensor volume of 100 ?m depth, 250 ?m width, and 1 mm length. The mean roughness of the core surface obtained by the AFM images was 231.7 nm, which is relatively smooth. Results of the tensile test indicated that the fibers have sufficient mechanical strength to resist damage from further processing. The multi-D-shaped optical fiber as a high sensitive refractive-index sensor to detect changes in the surrounding refractive index was studied. The results for different concentrations of sucrose solution show that a resolution of 1.27 × 10?3–3.13 × 10?4 RIU is achieved for refractive indices in the range of 1.333 to 1.403, suggesting that the multi-D-shaped fibers are attractive for chemical, biological, and biochemical sensing with aqueous solutions. PMID:22399908

  11. Elliptical-core two mode fiber sensors and devices incorporating photoinduced refractive index gratings

    NASA Technical Reports Server (NTRS)

    Greene, Jonathan A.; Miller, Mark S.; Starr, Suzanne E.; Fogg, Brian R.; Murphy, Kent A.; Claus, Richard O.; Vengsarkar, Ashish M.

    1991-01-01

    Results of experiments performed using germanium-doped, elliptical core, two-mode optical fibers whose sensitivity to strain was spatially varied through the use of chirped, refractive-index gratings permanently induced into the core using Argon-ion laser light are presented. This type of distributed sensor falls into the class of eighted-fiber sensors which, through a variety of means, weight the strain sensitivity of a fiber according to a specified spatial profile. We describe results of a weighted-fiber vibration mode filter which successfully enhances the particular vibration mode whose spatial profile corresponds to the profile of the grating chirp. We report on the high temperature survivability of such grating-based sensors and discuss the possibility of multiplexing more than one sensor within a single fiber.

  12. Improvement in refractive index sensitivity by means of internally curved long period fiber gratings

    NASA Astrophysics Data System (ADS)

    Chiavaioli, F.; Trono, C.; Baldini, F.

    2014-05-01

    A novel configuration of long period fiber grating (LPFG), based on a specially designed refractive index (RI) profile, was manufactured and studied. The internally manufactured geometric structure is characterized by grating planes tilted at increasing angles, as moving away from the center of symmetry of the structure towards its both edges. This structure reproduces the bending of an optical fiber and improves the RI sensitivity of an LPG to the external surrounding medium. A three-fold enhancement in the RI sensitivity was experimentally proved, thus giving a further contribution towards the development of more sensitive RI sensors based on optical fiber LPGs.

  13. Design of a long working distance graded index fiber lens with a low NA for fiber-optic probe in OCT application

    NASA Astrophysics Data System (ADS)

    Sun, Xiaoguang; Li, Jie

    2014-02-01

    A fiber-optic probe for optical coherence tomography (OCT) applications typically includes a short section of graded index (GRIN) fiber fused onto a single-mode (SM) fiber. The GRIN fiber acts as a lens to focus the output of the SM fiber and to collect the reflected light from the sample. In this paper we will use the beam propagation method (BPM) to analyze the output beam characteristics such as beam radius and working distance, and then compare these with the measured results. With this tool we can design a GRIN fiber lens to achieve a long working distance without degrading the system performance.

  14. Accurate Modeling of Fiber OPAs with Nonlinear Ellipse Rotation Terms in the Split-Step Fourier Method

    Microsoft Academic Search

    M. E. Marhic; L. G. Kazovsky; A. A. Rieznik; H. L. Fragnito

    We improve the accuracy of the split-step Fourier method by exactly treating nonlinear ellipse rotation terms. Results obtained this way for two-pump OPAs are significantly different from those obtained by neglecting ellipse rotation terms ? 2006 Optical Society of America OCIS codes: (060.2320) Fiber optics amplifiers and oscillators; (190.4370) Nonlinear optics, fibers

  15. Optical Fiber Refractive Index Sensor for Chloride Ion Monitoring

    Microsoft Academic Search

    Cathy Chung Chun Lam; Rajesh Mandamparambil; Tong Sun; Kenneth T. V. Grattan; Sreejith V. Nanukuttan; Su E. Taylor; P. A. Muhammed Basheer

    2009-01-01

    The development of a reflective, gold-coated long-period grating-based sensor for the measurement of chloride ions in solution is discussed. The sensor scheme is based around a long-period fiber grating (LPG)-based Michelson interferometer where the sensor was calibrated and evaluated in the laboratory using sodium chloride solutions, over a wide range of concentrations, from 0.01 to 4.00 M. The grating response

  16. Numerical analysis of refractive index sensitivity of long-period gratings in photonic crystal fiber

    Microsoft Academic Search

    Yinian Zhu; Zonghu He; Ji?í Ka?ka; Henry Du

    2008-01-01

    The modal coupling properties and resonance spectral response of long-period gratings (LPGs) in index-guiding photonic crystal fiber (PCF) are numerically investigated with respect to its sensitivity to changes in the index of refraction of the measurand in the PCF air channels using a full-vectorial mode solver combined with frequency-domain method. We show that the shift of wavelength resonance of a

  17. Experimental demonstration of the frequency shift of bandgaps in photonic crystal fibers due to refractive index scaling

    Microsoft Academic Search

    G. Antonopoulos; F. Benabid; T. A. Birks; D. M. Bird; J. C. Knight; P. St. J. Russell

    2006-01-01

    Experimental demonstration of the frequency shift of photonic bandgaps due to refractive index scaling using D2O-filled hollow-core photonic crystal fibers is presented. The results confirm a simple scaling law for bandgaps in fibers in which the low-index medium is varied.

  18. Successful IEEE 802.11n 2-channel MIMO transmission over standard graded index multimode fiber in passband

    Microsoft Academic Search

    Lukasz Maksymiuk; Jerzy Siuzdak

    2012-01-01

    We present a successful transmission of an IEEE 802.11n 2×2 Multiple Input — Multiple Output radio signal over standard graded index multimode fiber at several kilometers length. For the first time commercially available Access Points were used in the MIMO over multimode fiber experiment. Transmission was carried above the baseband of the multimode fiber (in passband), the electrical carrier was

  19. Ultra-weak FBG and its refractive index distribution in the drawing optical fiber.

    PubMed

    Guo, Huiyong; Liu, Fang; Yuan, Yinquan; Yu, Haihu; Yang, Minghong

    2015-02-23

    For the online writing of ultra-weak fiber Bragg gratings (FBGs) in the drawing optical fibers, the effects of the intensity profile, pulse fluctuation and pulse width of the excimer laser, as well as the transverse and longitudinal vibrations of the optical fiber have been investigated. Firstly, using Lorentz-Loren equation, Gladstone-Dale mixing rule and continuity equation, we have derived the refractive index (RI) fluctuation along the optical fiber and the RI distribution in the FBG, they are linear with the gradient of longitudinal vibration velocity. Then, we have prepared huge amounts of ultra-weak FBGs in the non-moving optical fiber and obtained their reflection spectra, the measured reflection spectra shows that the intensity profile and pulse fluctuation of the excimer laser, as well as the transverse vibration of the optical fiber are little responsible for the inconsistency of ultra-weak FBGs. Finally, the effect of the longitudinal vibration of the optical fiber on the inconsistency of ultra-weak FBGs has been discussed, and the vibration equations of the drawing optical fiber are given in the appendix. PMID:25836517

  20. Fiber optic liquid crystalline hydrostatic pressure sensor with gradient-index rod lenses

    Microsoft Academic Search

    Tomasz R. Wolinski; Leszek R. Staronski; Aleksandra Jarmolik; Andrzej W. Domanski

    1994-01-01

    A further development of the fiber optic hydrostatic pressure sensor with a liquid crystal film acting as a sensing element is presented. To enhance the amount of the optical signal entering the liquid crystal optrode gradient index (GRIN) rod lenses have been used in the pressure environment. The paper discusses the effect of stress induced birefringence in a GRIN lens,

  1. Refractive Index Sensing in an All-Solid Twin-Core Photonic Bandgap Fiber

    Microsoft Academic Search

    Wu Yuan; Graham E. Town; Ole Bang

    2010-01-01

    We describe a highly sensitive refractive index sensor based on a twin-core coupler in an all-solid photonic bandgap guiding optical fiber. A single hole acts as a microfluidic channel for the analyte, which modifies the coupling between the cores, and avoids the need for selective filling. By operating in the bandgap guiding regime the proposed sensor is capable of measuring

  2. Ultrasensitive refractive index sensor based on twin-core photonic bandgap fibers

    Microsoft Academic Search

    Wu Yuan; Graham E. Town; Ole Bang

    2009-01-01

    We have theoretically investigated twin-core all-solid photonic bandgap fibers (PBGFs) for evanescent wave sensing of refractive index within one single microfluidic analyte channel centered between the two cores. The sensor can achieve ultrahigh sensitivity by detecting the change in transmission. We find novel features in the sensing characteristics: the sensitivity is higher at the short wavelength edge of a bandgap

  3. Etching Bragg gratings in Panda fibers for the temperature-independent refractive index sensing.

    PubMed

    Li, Jie; Wang, Hao; Sun, Li-Peng; Huang, Yunyun; Jin, Long; Guan, Bai-Ou

    2014-12-29

    We demonstrate the evolution of the Bragg gratings inscribed in Panda fibers with chemical etching. The resonance wavelengths can blueshift with cladding reduction similar to the conventional counterparts. But the wavelength separation between the two polarizations is co-determined by the stress and the asymmetric shape effects. The fast and slow axes of the fiber can be reversed with each other and zero birefringence can be achieved by chemical etching the structure. When the stress-applying parts of the fiber are removed, the finalizing grating can be exploited for the temperature-independent refractive index sensing, since the modes corresponding to the two polarizations exhibit the dissimilar responses to the external refractive index change but the same response to temperature. Our device is featured with easy achievement, spectral controllability, and relative robustness. PMID:25607160

  4. Walk Ratio (Step Length/Cadence) as a Summary Index of Neuromotor Control of Gait: Application to Multiple Sclerosis

    ERIC Educational Resources Information Center

    Rota, Viviana; Perucca, Laura; Simone, Anna; Tesio, Luigi

    2011-01-01

    In healthy adults, the step length/cadence ratio [walk ratio (WR) in mm/(steps/min) and normalized for height] is known to be constant around 6.5 mm/(step/min). It is a speed-independent index of the overall neuromotor gait control, in as much as it reflects energy expenditure, balance, between-step variability, and attentional demand. The speed…

  5. Optical properties of side-polished polarization maintaining fiber coupled with a high index planar waveguide

    NASA Astrophysics Data System (ADS)

    Kim, Kwang Taek; Yoon, Dae Sung; Kwoen, Gyeong-il

    2004-01-01

    We have investigated the behavior of an asymmetric directional coupler made of a side-polished polarization maintaining (PM) fiber covered with a high index planar waveguide (PWG). The effects of the modal birefringence of the side-polished PM fiber, the structural parameters of PWG and the deformation of the PM fiber on the transmission characteristics of the coupler has been measured and explained. Experimental results show that the coincidence of resonance wavelengths for transverse electric and transverse magnetic polarizations can be achieved through proper control of device parameters. Furthermore, the fabricated devices revealed a superior immunity to deformation of PM fibers. The device fabrication procedure, particularly, alignment of the birefringence axis with PWG is described in detail.

  6. Measurement of resonant and nonresonant induced refractive index changes in Yb-doped fiber grating amplifier.

    PubMed

    Shapira, Y P; Oscar, D; Spektor, B; Smulakovsky, V; Horowitz, M

    2015-02-15

    We have measured the refractive index change (RIC) induced in a fiber Bragg grating (FBG) written in a Yb-doped fiber amplifier (YB-FBG) because of the amplifier pumping. The measurement was performed by exploiting the high sensitivity of the YD-FBG transmission to the RIC. We have separated between electronic and thermal contributions to the RIC based on the difference between the time-scales of the two effects. Because of high UV-induced loss in FBGs, the thermal contribution to the RIC is increased, in comparison with previously published work, where no grating was written in the fiber amplifier. The measurement method allows us to find the sign of each contribution to the RIC, and it requires only a few centimeters of fiber. Optimal pumping scheme for reducing the RIC in a YB-FBG is studied. PMID:25680141

  7. High sensitivity refractive index sensor based on adiabatic tapered optical fiber deposited with nanofilm by ALD.

    PubMed

    Zhu, Shan; Pang, Fufei; Huang, Sujuan; Zou, Fang; Dong, Yanhua; Wang, Tingyun

    2015-06-01

    Atomic layer deposition (ALD) technology is introduced to fabricate a high sensitivity refractive index sensor based on an adiabatic tapered optical fiber. Different thickness of Al2O3 nanofilm is coated around fiber taper precisely and uniformly under different deposition cycles. Attributed to the high refractive index of the Al2O3 nanofilm, an asymmetry Fabry-Perot like interferometer is constructed along the fiber taper. Based on the ray-optic analysis, total internal reflection happens on the nanofilm-surrounding interface. With the ambient refractive index changing, the phase delay induced by the Goos-Hänchen shift is changed. Correspondingly, the transmission resonant spectrum shifts, which can be utilized for realizing high sensitivity sensor. The high sensitivity sensor with 6008 nm/RIU is demonstrated by depositing 3000 layers Al2O3 nanofilm as the ambient refractive index is close to 1.33. This high sensitivity refractive index sensor is expected to have wide applications in biochemical sensors. PMID:26072758

  8. Mismatch Consideration in Circular Core Mono-mode Graded Index Fiber of Triangular Refractive Index Profile Excitation via Hemispherical Microlens on the Fiber Tip

    NASA Astrophysics Data System (ADS)

    Bose, Ashima; Gangopadhyay, Sankar; Saha, Subhas Chandra

    2012-12-01

    We report what, as per our knowledge, is the first theoretical investigation of the excitation efficiency in presence of possible transverse and angular misalignments in case of single-mode circular core triangular refractive index profile fiber excitation by laser diode via hemispherical microlens on the fiber tip. The present analysis takes into consideration limited aperture allowable by the hemispherical lens. Using ABCD matrix for refraction of paraxial rays by a hemispherical microlens, we prescribe analytical expressions for the coupling efficiencies in presence of the said mismatches. The evaluation of the concerned efficiencies and associated losses will require little computations. The results found will be extremely useful in the field of optimum launch optics involving such coupler.

  9. Refractive index sensitivity of nano-film coated long-period fiber gratings.

    PubMed

    Zou, Fang; Liu, Yunqi; Deng, Chuanlu; Dong, Yanhua; Zhu, Shan; Wang, Tingyun

    2015-01-26

    We demonstrate the fabrication of long-period fiber gratings (LPFGs) coated with high index nano-film using the atomic layer deposition (ALD) technology. Higher index sensitivity can be achieved in the transition region of the coated LPFGs. For the LPFG coated by nano-film with a thickness of 100 nm, the high index sensitivity of 3000 nm/RIU and the expanded index sensitive range are obtained. The grating contrast of the over-coupled LPFGs and conventional LPFGs are measured and the over-coupled gratings are found to have a higher contrast in the transition region. The cladding modes transition is observed experimentally with increasing surrounding index using an infrared camera. The theoretical model of the hybrid modes in four-layer cylindrical waveguide is proposed for numerical simulation. The experimental results are well consistent with theoretical analysis. PMID:25835871

  10. Use of optical fibers in spectrophotometry

    NASA Technical Reports Server (NTRS)

    Ramsey, Lawrence W.

    1988-01-01

    The use of single or small numbers of fiber optic fibers in astronomical spectroscopy with the goal of greater spectrophotometric and radial velocity accuracy is discussed. The properties of multimode step index fibers which are most important for this application are outlined, as are laboratory tests of currently available fibers.

  11. Dietary fiber intake, dietary glycemic index and load, and body mass index: a cross-sectional study of 3931 Japanese women aged 18–20 years

    Microsoft Academic Search

    K Murakami; S Sasaki; H Okubo; Y Takahashi; Y Hosoi; M Itabashi

    2007-01-01

    Objective:Few observational studies have investigated dietary fiber intake and dietary glycemic index (GI) and glycemic load (GL) simultaneously in relation to obesity, particularly in non-Western populations. We examined the associations between dietary fiber intake and dietary GI and GL, and body mass index (BMI) in young Japanese women.Design:Cross-sectional study.Subjects:A total of 3931 female Japanese dietetic students aged 18–20 years from

  12. Enhanced refractive index sensor using a combination of a long period fiber grating and a small core singlemode fiber structure

    NASA Astrophysics Data System (ADS)

    Wu, Qiang; Chan, Hai Ping; Yuan, Jinhui; Ma, Youqiao; Yang, Minwei; Semenova, Yuliya; Yan, Binbin; Wang, Pengfei; Yu, Chongxiu; Farrell, Gerald

    2013-09-01

    An enhanced refractive index (RI) sensor based on a combination of a long period fiber grating (LPG) and a small core singlemode fiber (SCSMF) structure is proposed and developed. Since the LPG and SCSMF transmission spectra experience a blue and a red shift respectively as the surrounding RI (SRI) increases, the sensitivity is improved by measuring the separation between the resonant wavelengths of the LPG and SCSMF structures. Experimental results show that the sensor has a sensitivity of 1028 nm/SRI unit in the SRI range from 1.422 to 1.429, which is higher than individual sensitivities of either structure alone used in the experiment. Experimental results agree well with simulation results.

  13. Fiber optic liquid crystalline hydrostatic pressure sensor with gradient-index rod lenses

    NASA Astrophysics Data System (ADS)

    Wolinski, Tomasz R.; Staronski, Leszek R.; Jarmolik, Aleksandra; Domanski, Andrzej W.

    1994-11-01

    A further development of the fiber optic hydrostatic pressure sensor with a liquid crystal film acting as a sensing element is presented. To enhance the amount of the optical signal entering the liquid crystal optrode gradient index (GRIN) rod lenses have been used in the pressure environment. The paper discusses the effect of stress induced birefringence in a GRIN lens, its influence on defocusing phenomena under pressure and the optimized configuration of the fiber optic liquid crystal sensor preset for a required range of pressure.

  14. Spectral behavior in thinned long period gratings: effects of fiber diameter on refractive index sensitivity.

    PubMed

    Iadicicco, Agostino; Campopiano, Stefania; Giordano, Michele; Cusano, Andrea

    2007-10-01

    We report the experimental investigation of the sensitivity characteristics to the surrounding refractive index (SRI) in thinned long period gratings (LPGs) for a wide range of fiber diameters and different low-orders cladding modes. Wet chemical etching combined with microscopic and spectral analysis allow us to experimentally retrieve the SRI sensitivity characteristics of thinned LPGs. The obtained results allow us to identify accurately the dependence of the sensitivity characteristics on the fiber radius, taking into account the SRI range and the order mode. This provides a useful tool to identify the thinned structure able to fulfill the sensitivity requirements by maintaining an acceptable robustness level. PMID:17906722

  15. Fabrication quality analysis of a fiber optic refractive index sensor created by CO2 laser machining.

    PubMed

    Chen, Chien-Hsing; Yeh, Bo-Kuan; Tang, Jaw-Luen; Wu, Wei-Te

    2013-01-01

    This study investigates the CO2 laser-stripped partial cladding of silica-based optic fibers with a core diameter of 400 ?m, which enables them to sense the refractive index of the surrounding environment. However, inappropriate treatments during the machining process can generate a number of defects in the optic fiber sensors. Therefore, the quality of optic fiber sensors fabricated using CO2 laser machining must be analyzed. The results show that analysis of the fiber core size after machining can provide preliminary defect detection, and qualitative analysis of the optical transmission defects can be used to identify imperfections that are difficult to observe through size analysis. To more precisely and quantitatively detect fabrication defects, we included a tensile test and numerical aperture measurements in this study. After a series of quality inspections, we proposed improvements to the existing CO2 laser machining parameters, namely, a vertical scanning pathway, 4 W of power, and a feed rate of 9.45 cm/s. Using these improved parameters, we created optical fiber sensors with a core diameter of approximately 400 ?m, no obvious optical transmission defects, a numerical aperture of 0.52 ± 0.019, a 0.886 Weibull modulus, and a 1.186 Weibull-shaped parameter. Finally, we used the optical fiber sensor fabricated using the improved parameters to measure the refractive indices of various solutions. The results show that a refractive-index resolution of 1.8 × 10(-4) RIU (linear fitting R2 = 0.954) was achieved for sucrose solutions with refractive indices ranging between 1.333 and 1.383. We also adopted the particle plasmon resonance sensing scheme using the fabricated optical fibers. The results provided additional information, specifically, a superior sensor resolution of 5.73 × 10(-5) RIU, and greater linearity at R2 = 0.999. PMID:23535636

  16. Fabrication Quality Analysis of a Fiber Optic Refractive Index Sensor Created by CO2 Laser Machining

    PubMed Central

    Chen, Chien-Hsing; Yeh, Bo-Kuan; Tang, Jaw-Luen; Wu, Wei-Te

    2013-01-01

    This study investigates the CO2 laser-stripped partial cladding of silica-based optic fibers with a core diameter of 400 ?m, which enables them to sense the refractive index of the surrounding environment. However, inappropriate treatments during the machining process can generate a number of defects in the optic fiber sensors. Therefore, the quality of optic fiber sensors fabricated using CO2 laser machining must be analyzed. The results show that analysis of the fiber core size after machining can provide preliminary defect detection, and qualitative analysis of the optical transmission defects can be used to identify imperfections that are difficult to observe through size analysis. To more precisely and quantitatively detect fabrication defects, we included a tensile test and numerical aperture measurements in this study. After a series of quality inspections, we proposed improvements to the existing CO2 laser machining parameters, namely, a vertical scanning pathway, 4 W of power, and a feed rate of 9.45 cm/s. Using these improved parameters, we created optical fiber sensors with a core diameter of approximately 400 ?m, no obvious optical transmission defects, a numerical aperture of 0.52 ± 0.019, a 0.886 Weibull modulus, and a 1.186 Weibull-shaped parameter. Finally, we used the optical fiber sensor fabricated using the improved parameters to measure the refractive indices of various solutions. The results show that a refractive-index resolution of 1.8 × 10?4 RIU (linear fitting R2 = 0.954) was achieved for sucrose solutions with refractive indices ranging between 1.333 and 1.383. We also adopted the particle plasmon resonance sensing scheme using the fabricated optical fibers. The results provided additional information, specifically, a superior sensor resolution of 5.73 × 10?5 RIU, and greater linearity at R2 = 0.999. PMID:23535636

  17. Fiber optic based multiparametric spectroscopy in vivo: Toward a new quantitative tissue vitality index

    NASA Astrophysics Data System (ADS)

    Kutai-Asis, Hofit; Barbiro-Michaely, Efrat; Deutsch, Assaf; Mayevsky, Avraham

    2006-02-01

    In our previous publication (Mayevsky et al SPIE 5326: 98-105, 2004) we described a multiparametric fiber optic system enabling the evaluation of 4 physiological parameters as indicators of tissue vitality. Since the correlation between the various parameters may differ in various pathophysiological conditions there is a need for an objective quantitative index that will integrate the relative changes measured in real time by the multiparametric monitoring system into a single number-vitality index. Such an approach to calculate tissue vitality index is critical for the possibility to use such an instrument in clinical environments. In the current presentation we are reporting our preliminary results indicating that calculation of an objective tissue vitality index is feasible. We used an intuitive empirical approach based on the comparison between the calculated index by the computer and the subjective evaluation made by an expert in the field of physiological monitoring. We used the in vivo brain of rats as an animal model in our current studies. The rats were exposed to anoxia, ischemia and cortical spreading depression and the responses were recorded in real time. At the end of the monitoring session the results were analyzed and the tissue vitality index was calculated offline. Mitochondrial NADH, tissue blood flow and oxy-hemoglobin were used to calculate the vitality index of the brain in vivo, where each parameter received a different weight, in each experiment type based on their significance. It was found that the mitochondrial NADH response was the main factor affected the calculated vitality index.

  18. Design of photonic crystal fiber long-period grating refractive index sensor

    NASA Astrophysics Data System (ADS)

    Kanka, Jiri; Zhu, Yinian; He, Zonghu; Du, Henry

    2009-05-01

    Numerical optimization of photonic crystal fiber (PCF) structures for refractive index sensors based on long period gratings inscribed in PCFs has been performed. The optimization procedure employs the Nelder-Mead downhill simplex algorithm. This direct-search method attempts to minimize a scalar-valued nonlinear function of N real variables (called the objective function) using only function values, without any derivative information. An inverse design approach utilizes the objective function constructed using desired sensing characteristics. For the modal analysis of the PCF structure a fully-vectorial solver based on the finite element method is called by the objective function. The dispersion optimization of PCFs is aimed at achieving a high sensitivity of measurement of refractive index of analytes infiltrated into the air holes for the refractive index and probe wavelength ranges of interest. We have restricted our work to the index-guiding solid-core PCF structures with hexagonally arrayed air holes.

  19. High-bandwidth graded-index polymer optical fiber with high-temperature stability

    Microsoft Academic Search

    Takaaki Ishigure; Masataka Sato; Atsushi Kondo; Yasuhiro Koike

    2002-01-01

    A newly developed graded-index polymer optical fiber (GI-POF) with high-temperature and high-humidity stability was proposed. As it was found that the high numerical aperture and high glass transition temperature (Tg) at the core center of the GI-POF were key issues to achieve both high-temperature and humidity stability, a partially fluorinated polymer material was adopted to obtain both characteristics in the

  20. Design of photonic crystal fiber long-period grating refractive index sensor

    Microsoft Academic Search

    Jiri Kanka; Yinian Zhu; Zonghu He; Henry Du

    2009-01-01

    Numerical optimization of photonic crystal fiber (PCF) structures for refractive index sensors based on long period gratings inscribed in PCFs has been performed. The optimization procedure employs the Nelder-Mead downhill simplex algorithm. This direct-search method attempts to minimize a scalar-valued nonlinear function of N real variables (called the objective function) using only function values, without any derivative information. An inverse

  1. Electrostrictive contribution to the intensity-dependent refractive index of optical fibers

    Microsoft Academic Search

    Eric L. Buckland; Robert W. Boyd

    1996-01-01

    We show that electrostriction contributes significantly to self-action effects in optical fibers, adding 19% to the nonlinear refractive index for fields that vary slowly compared with the ,1-ns time scale of the acoustic response. Electrostriction also modifies the tensor nature of the nonlinear-optical response. The electrostrictive nonlinearity is the origin of the observed difference between measurements of n2 with cw

  2. Analysis on the saturation of refractive index modulation in fiber Bragg gratings (FBGs) written by partially coherent UV beams.

    PubMed

    Mahakud, Ramakanta; Prakash, Om; Nakhe, Shankar V; Dixit, Sudhir Kumar

    2012-04-20

    We present an analysis on the saturation of refractive index modulation of fiber Bragg gratings written in nonhydrogenated Ge-B co-doped single-mode photosensitive optical fiber by partially coherent pulsed UV beams. The UV beams of different spatial coherence properties were generated by second harmonic conversion of high repetition rate, high average power copper vapor laser (CVL) oscillators with different optical resonators. It is observed that for UV beams of higher spatial coherence, the fiber Bragg grating reflectivity growth was faster and saturation of refractive index modulation was higher. The experimental results are explained with the help of a physical model based on exponential decay of defect centers per unit volume on UV absorption in the fiber core. The subsequent increase in the refractive index was attributed to the structural modification and densification of the fiber core. PMID:22534886

  3. Further analysis of focusing performance of an ultra-small gradient-index fiber probe

    NASA Astrophysics Data System (ADS)

    Wang, Chi; Bi, Shubo; Xia, Xueqin; Yu, Yingjie

    2014-01-01

    In order to optimize ultra-small gradient-index (GRIN) fiber probes and provide a theoretical prediction for the fabrication of such probes with high performance, focusing performance of the GRIN fiber probe is further analyzed based on the optical characteristic parameters. According to the optical model of the GRIN fiber probe and its mathematical expressions of characteristic parameters, the three-dimensional (3-D) function diagram is used for analyzing the impact of the lengths of probe components on the characteristic parameters. Partial derivatives of the mathematical expressions of characteristics are derived to analyze the mutation of focusing performance caused by the different lengths of probe components. According to the analytical results, our predictions suggest that focusing performance could be reflected through the 3-D function diagram between the characteristic parameters and the continuous change of the lengths of probe components. In addition, mutation occurs in the focusing performance of the GRIN fiber probe when the length of probe components changes. The research results are of practical guiding significance for the fabrication of GRIN fiber probes requiring specific optical focusing performance.

  4. 10 Gbit\\/s short-reach transmission over 35 m large-core graded-index polymer optical fiber

    Microsoft Academic Search

    Roman Kruglov; Sven Loquai; Christian-Alexander Bunge; Olaf Ziemann; Bernhard Schmauss; Juri Vinogradov

    2011-01-01

    In the paper we demonstrate robust 10 Gbit\\/s short-reach transmission over 35 m of 1- mm core-diameter graded-index polymer optical fiber with very low cost components and DMT modulation. With this scheme reliable high-speed short-reach interconnects are feasible that can be easily combined to fiber ribbons. OCIS codes: (060.2330) Fiber optics communications; (200.4650) Optical interconnects

  5. Principal Modes in Graded-Index Multimode Fiber in Presence of Spatial and Polarization-Mode Coupling

    Microsoft Academic Search

    Mahdieh B. Shemirani; Wei Mao; Rahul Alex Panicker; Joseph M. Kahn

    2009-01-01

    Power-coupling models are inherently unable to describe certain mode coupling effects in multimode fiber (MMF) when using coherent sources at high bit rates, such as polarization dependence of the impulse response. We develop a field-coupling model for propagation in graded-index MMF, analogous to the principal-states model for polarization-mode dispersion in single-mode fiber. Our model allows computation of the fiber impulse

  6. Highly Sensitive Monolithic Silicon Photonic Crystal Fiber Tip Sensor for Simultaneous Measurement of Refractive Index and Temperature

    Microsoft Academic Search

    Il Woong Jung; Bryan Park; J. Provine; Roger T. Howe; Olav Solgaard

    2011-01-01

    Fiber optic sensors have applications in the measure- ment of a wide range of physical properties such as temperature, pressure, and refractive index. These sensors are immune to elec- tromagnetic interference, made of high temperature dielectric ma- terials and hence can be deployed in harsh environments where conventional electronics would fail. Photonic crystal (PC) fiber tip sensors are highly sensitive

  7. Speckle In Optical Fibers

    NASA Astrophysics Data System (ADS)

    Rawson, Eric G.; Goodman, Joseph W.

    1980-12-01

    With a sufficiently narrow source spectrum, and either fiber movement or source frequency shift, a changing speckle pattern exists at a multimode optical fiber output plane which results in signal power fluctuations known as "modal noise." For the case of a step-index optical fiber, we report the measurement and analysis of the speckle spatial frequency distribution as a function of fiber parameters, and the correlation of two speckle patterns as a function of source frequency difference. We show how knowledge of the frequency correlation function and the source spectrum can be used to determine the speckle contrast. Again for a step-index fiber, we report the analysis and measurement of the probability density function of the optical power received by a detector at the end of a fiber as a function of the speckle's contrast and including the possibility of spatial filtration of the speckle, as might occur at a misaligned connector.

  8. TCF-MMF-TCF fiber structure based interferometer for refractive index sensing

    NASA Astrophysics Data System (ADS)

    Fu, Haiwei; Li, Huidong; Shao, Min; Zhao, Na; Liu, Yinggang; Li, Yan; Yan, Xu; Liu, Qinpeng

    2015-06-01

    A liquid refractive index (RI) sensor based on in-fiber Mach-Zehnder interferometer (MZI) by sandwiching multi-mode fiber (MMF) between two short sections of thinned core fiber (TCF) is proposed in this paper. The first section of TCF excites the high-order modes and the second section TCF couples the core mode and high-order modes into lead-out SMF to form intermodal interference. The sensor with MMF length of 20 mm and TCFs length of 1 mm was fabricated. The transmission spectrum variation of the sensor with respect to surrounding refractive index (SRI) has been studied by experiment. The results show that the central wavelength of dips/peaks shifting had a good linearity with SRI. The RI sensitivity of the sensor is 130.00 nm/RIU over the RI range of 1.3333-1.4182. The RI sensitivity increase to 433.60 nm/RIU after etching the MMF cladding of the sensor. The sensor keeps low dependence on temperature before and after etching.

  9. Effects of Dantrolene on Steps of Excitation-Contraction Coupling in Mammalian Skeletal Muscle Fibers

    PubMed Central

    Szentesi, Péter; Collet, Claude; Sárközi, Sándor; Szegedi, Csaba; Jona, István; Jacquemond, Vincent; Kovács, László; Csernoch, László

    2001-01-01

    The effects of the muscle relaxant dantrolene on steps of excitation-contraction coupling were studied on fast twitch muscles of rodents. To identify the site of action of the drug, single fibers for voltage-clamp measurements, heavy SR vesicles for calcium efflux studies and solubilized SR calcium release channels/RYRs for lipid bilayer studies were isolated. Using the double Vaseline-gap or the silicone-clamp technique, dantrolene was found to suppress the depolarization-induced elevation in intracellular calcium concentration ([Ca2+]i) by inhibiting the release of calcium from the SR. The suppression of [Ca2+]i was dose-dependent, with no effect at or below 1 ?M and a 53 ± 8% (mean ± SEM, n = 9, cut fibers) attenuation at 0 mV with 25 ?M of extracellularly applied dantrolene. The drug was not found to be more effective if injected than if applied extracellularly. Calculating the SR calcium release revealed an equal suppression of the steady (53 ± 8%) and of the early peak component (46 ± 6%). The drug did not interfere with the activation of the voltage sensor in as much as the voltage dependence of both intramembrane charge movements and the L-type calcium currents (ICa) were left, essentially, unaltered. However, the inactivation of ICa was slowed fourfold, and the conductance was reduced from 200 ± 16 to 143 ± 8 SF?1 (n = 10). Dantrolene was found to inhibit thymol-stimulated calcium efflux from heavy SR vesicles by 44 ± 10% (n = 3) at 12 ?M. On the other hand, dantrolene failed to affect the isolated RYR incorporated into lipid bilayers. The channel displayed a constant open probability for as long as 30–50 min after the application of the drug. These data locate the binding site for dantrolene to be on the SR membrane, but be distinct from the purified RYR itself. PMID:11585849

  10. Optical fiber sensor based on capillary wall for highly-sensitive refractive index measurement

    NASA Astrophysics Data System (ADS)

    Liu, Yun; Peng, Wei; Zhang, Xinpu; Qian, Siyu

    2014-05-01

    This paper reports a temperature-compensated fiber-optic refractive index (RI) sensor for high sensitivity measurement. The sensor includes a piece of fused-silica capillary (FSC) and a fiber Bragg grating (FBG), both of which are sandwiched by single-mode fibers (SMFs). When light from the lead-in SMF enters into the wall of the FSC that acts as a RI sensing element, multiple modes are excited and interfere to form fringes collected by the lead-out SMF. The FBG is fabricated adjunct to the FSC to compensate its temperature sensitivity. The FSC based sensor prototype is fabricated and sealed in a flow cell to test its performance. Experimental results show that the sensor is highly sensitive to RI, and the sensitivity in the tested RI range from 1.33 to 1.35 is 698.52 nm/RIU and from 1.35 to 1.37 is 1061.78 nm/RIU. The temperature sensitivity of the FSC is -0.173 nm/°C, which is compensated by the FBG. This capillary wall based sensor can be further developed as a miniaturized fiber optic biosensor for biochemical application.

  11. Investigation of refractive index distribution in different photonic crystal fiber elements

    NASA Astrophysics Data System (ADS)

    Jaroszewicz, Leszek R.; Kujawi?ska, Ma?gorzata; Stasiewicz, Karol; Mar?, Pawe?; Nasi?owski, Tomasz; Murawski, Micha?; Szyma?ski, Micha?; Siwicki, Bart?omiej; Krauze, Wojciech

    2011-09-01

    The paper presents the last data regarding new elements based on photonic crystal fibers such as the low-loss patch cord with a single mode fiber, the fused coupler, the asymmetric coupler for an active fiber power pump. Their fundamental optical characteristics including wavelength depending loss as a coupling ratio are presented in this paper as well as their inner structure (cross section) obtained by SEM. However, the use of SEM for the investigation of the inner element structure is destructive, thus in the last part of the paper we present the tomographic in-line determination of geometry and refractive index distribution changes along the investigated photonic structure. The analysis of different approaches to the photonic crystal fiber data capture with a sufficient optical resolution is given. The data obtained from the Mach-Zehnder interferometer with different laser sources as well as from the in-line digital holographic setup are presented and compared. The further enhancement required for the digital in-line holography is discussed.

  12. Experimental analysis of distributed pump absorption and refractive index changes in Yb-doped fibers using acousto-optic interaction.

    PubMed

    Alcusa-Sáez, E P; Díez, A; Andrés, M V

    2015-03-01

    In-fiber acousto-optic interaction is used to characterize the refractive index changes at the C band in a single-mode ytterbium-doped optical fiber under 980 nm pumping. The transmission notch created by the acoustic-induced coupling between the core mode and a cladding mode shifts to longer wavelengths when the pump is delivered to the fiber. The electronic contribution to the refractive index change is quantified from the wavelength shift. Using a time-resolved acousto-optic method, we investigate the distribution of pump absorption, and the resulting refractive index change profile, along sections of ytterbium-doped fiber exceeding 1 m long under different pump power levels. PMID:25723408

  13. Single mode tapered fiber-optic interferometer based refractive index sensor and its application to protein sensing.

    PubMed

    Yadav, T K; Narayanaswamy, R; Abu Bakar, M H; Kamil, Y Mustapha; Mahdi, M A

    2014-09-22

    We demonstrate refractive index sensors based on single mode tapered fiber and its application as a biosensor. We utilize this tapered fiber optic biosensor, operating at 1550 nm, for the detection of protein (gelatin) concentration in water. The sensor is based on the spectroscopy of mode coupling based on core modes-fiber cladding modes excited by the fundamental core mode of an optical fiber when it transitions into tapered regions from untapered regions. The changes are determined from the wavelength shift of the transmission spectrum. The proposed fiber sensor has sensitivity of refractive index around 1500 nm/RIU and for protein concentration detection, its highest sensitivity is 2.42141 nm/%W/V. PMID:25321749

  14. Miniaturized two-photon microscope based on a flexible coherent fiber bundle and a gradient-index lens objective.

    PubMed

    Göbel, Werner; Kerr, Jason N D; Nimmerjahn, Axel; Helmchen, Fritjof

    2004-11-01

    We present a miniature, flexible two-photon microscope consisting of a fused coherent optical fiber bundle with 30,000 cores and a gradient-index lens objective. The laser focus of a standard two-photon laser-scanning microscope was scanned over the entrance surface of the fiber bundle, resulting in sequential coupling into individual cores. Fluorescent light was detected through the fiber bundle. Micrometer-sized fluorescent beads and pollen grains were readily resolved. In addition, fluorescently labeled blood vessels were imaged through the fiber bundle in rat brain in vivo. PMID:15584281

  15. Birefringent microfiber-based fiber loop mirrors for tunable filters and refractive index sensors

    NASA Astrophysics Data System (ADS)

    Jin, Wa; Xuan, Haifeng; Jin, Wei

    2013-05-01

    Highly birefringent (Hi-Bi) microfiber-based fiber loop mirrors (FLMs) were studied for tunable comb filters and refractive index (RI) sensors. RI sensitivity of up to 15,441 nm/RIU was experimentally demonstrated for the RI sensors and, for the tunable filter a thermal tuning coefficient of ~-2.35nm/°C was obtained for temperature from 20 to 90°C when it was immersed into water. The use of two cascaded Hi-Bi micro-tapers within a Sagnac loop allows more flexibility in controlling the transmission/reflection spectraums of the FLM. The length of the tapered Hi-Bi microfibers is on the order of centimeters, two orders of magnitude shorter than the conventional Hi-Bi fiber-based devices.

  16. Label free detection of DNA hybridization by refractive index tapered fiber biosensor

    NASA Astrophysics Data System (ADS)

    Zibaii, M. I.; Latifi, H.; Ghanati, E.; Gholami, M.; Hosseini, S. M.

    2010-04-01

    We demonstrate a simple refractive index sensor (RI) sensing system based on a biconical tapered optical fiber (BTOF), which is fabricated by heat pulling method, utilizing a CO2 laser. In this work we explore the application of these sensors for the detection of label free single stranded DNA (ssDNA) in real time. During the experiment, the target ssDNA did not need to be labeled with a fluorescent tag, which is expensive and complicated. The change in output optical transmission of the tapered fiber was recorded for Poly-L-Lysine (PLL) coating, ssDNA probe immobilization and hybridization. The result indicated that due to the hybridization with the complementary target ssDNA on the tapered surface, the RI of surrounding medium changes which leads to changes in the characteristics of the tapered region and change in the output power of the sensor.

  17. Loss properties due to Rayleigh scattering in different types of fiber

    Microsoft Academic Search

    Wang Zhi; Ren Guobin; Lou Shuqin; Jian Shuisheng

    2003-01-01

    The effects of fiber structure on Rayleigh scattering were investigated in detail. Some step-index fibers such as GeO2- and F-doped silica-based fibers and total-internal-reflection photonic crystal fiber are examined. The Rayleigh scattering loss (RSL) depends on the fiber materials and index profiles, and different types of fiber have different dependencies on those parameters because of the different optical power confinement

  18. Phase stepping and heterodyning in a fiber-based speckle shearing interferometer

    Microsoft Academic Search

    Jesus D. Valera; Julian D. Jones; David P. Towers; Clive H. Buckberry

    1995-01-01

    An optical, fiber-based, speckle shearing interferometer is described. The instrument uses a highly birefringent optical fiber to illuminate a test object with equal intensities of light guided by the orthogonal polarization eigenstates of the fiber. A Wollaston prism is used to obtain two sheared images with adjustable shear. Optical phase changes between the sheared images are readily achieved, without mechanical

  19. All fiber chirped-pulse amplification system based on compression in air-guiding photonic bandgap fiber

    Microsoft Academic Search

    J. Limpert; T. Schreiber; S. Nolte; H. Zellmer; A. Tünnermann

    2003-01-01

    We report on the experimental demonstration of an all fiber CPA system based on a step-index fiber stretcher and an air-guiding photonic crystal fiber compressor. The ultrafast fiber laser system producing an average power of 6.0 W with 100-fs pulses at 73 MHz, what corresponds to a peak power out of the compressor fiber of 0.82 MW. This completely fiber

  20. Note: Optical fiber milled by focused ion beam and its application for Fabry-Pérot refractive index sensor

    NASA Astrophysics Data System (ADS)

    Yuan, Wu; Wang, Fei; Savenko, Alexey; Petersen, Dirch Hjorth; Bang, Ole

    2011-07-01

    We introduce a highly compact fiber-optic Fabry-Pérot refractive index sensor integrated with a fluid channel that is fabricated directly near the tip of a 32 ?m in diameter single-mode fiber taper. The focused ion beam technique is used to efficiently mill the microcavity from the fiber side and finely polish the end facets of the cavity with a high spatial resolution. It is found that a fringe visibility of over 15 dB can be achieved and that the sensor has a sensitivity of ˜1731 nm/RIU (refractive index units) and a detection limit of ˜5.78 × 10-6 RIU. This miniature integrated all-in-fiber optofludic sensor may find use in minimal-invasive biomedical applications.

  1. Sex, body mass index, and dietary fiber intake influence the human gut microbiome.

    PubMed

    Dominianni, Christine; Sinha, Rashmi; Goedert, James J; Pei, Zhiheng; Yang, Liying; Hayes, Richard B; Ahn, Jiyoung

    2015-01-01

    Increasing evidence suggests that the composition of the human gut microbiome is important in the etiology of human diseases; however, the personal factors that influence the gut microbiome composition are poorly characterized. Animal models point to sex hormone-related differentials in microbiome composition. In this study, we investigated the relationship of sex, body mass index (BMI) and dietary fiber intake with the gut microbiome in 82 humans. We sequenced fecal 16S rRNA genes by 454 FLX technology, then clustered and classified the reads to microbial genomes using the QIIME pipeline. Relationships of sex, BMI, and fiber intake with overall gut microbiome composition and specific taxon abundances were assessed by permutational MANOVA and multivariate logistic regression, respectively. We found that sex was associated with the gut microbiome composition overall (p=0.001). The gut microbiome in women was characterized by a lower abundance of Bacteroidetes (p=0.03). BMI (>25 kg/m2 vs. <25 kg/m2) was associated with the gut microbiome composition overall (p=0.05), and this relationship was strong in women (p=0.03) but not in men (p=0.29). Fiber from beans and from fruits and vegetables were associated, respectively, with greater abundance of Actinobacteria (p=0.006 and false discovery rate adjusted q=0.05) and Clostridia (p=0.009 and false discovery rate adjusted q=0.09). Our findings suggest that sex, BMI, and dietary fiber contribute to shaping the gut microbiome in humans. Better understanding of these relationships may have significant implications for gastrointestinal health and disease prevention. PMID:25874569

  2. Development of a graded index microlens based fiber optical trap and its characterization using principal component analysis

    PubMed Central

    Nylk, J.; Kristensen, M. V. G.; Mazilu, M.; Thayil, A. K.; Mitchell, C. A.; Campbell, E. C.; Powis, S. J.; Gunn-Moore, F. J.; Dholakia, K.

    2015-01-01

    We demonstrate a miniaturized single beam fiber optical trapping probe based on a high numerical aperture graded index (GRIN) micro-objective lens. This enables optical trapping at a distance of 200?m from the probe tip. The fiber trapping probe is characterized experimentally using power spectral density analysis and an original approach based on principal component analysis for accurate particle tracking. Its use for biomedical microscopy is demonstrated through optically mediated immunological synapse formation. PMID:25909032

  3. Long-period gratings in photonic crystal fibers for sensing of external refractive index change and macro-bending

    Microsoft Academic Search

    Zonghu He; Yinian Zhu; Ryan T. Bise; Henry Du

    2006-01-01

    Long-period gratings (LPGs) have been fabricated in endlessly single mode photonic crystal fibers (ESM-PCFs) utilizing focused CO2 laser irradiation and residual stress relaxation technique. The responses of the ESM-PCF-LPGs to external refractive index and applied bending curvature have been investigated. As compared with the conventional fiber-based LPGs inscribed under the same condition, the ESM-PCF-LPGs exhibit higher sensitivity to external refractive

  4. High index-contrast all-solid photonic crystal fibers by pressure-assisted melt infiltration of silica matrices

    Microsoft Academic Search

    Ning da; Lothar Wondraczek; Markus A. Schmidt; Nicolai Granzow; Philip St. J. Russell

    2010-01-01

    All-solid photonic crystal fibers (PCFs) are created by pressure-assisted filling of low-melting-point chalcogenide and tellurite glasses into silica matrix fibers with channel diameters as small as 200nm. Overcoming to a large extent the problem of viscosity and, thus, process incompatibility of silica and non-silicate optical glasses, the technique provides a unique way of producing waveguiding devices with high core-cladding index-contrast,

  5. An efficient scheme of split-step Fourier method for fiber optic communication systems

    NASA Astrophysics Data System (ADS)

    Shao, Jing; Liang, Xiaojun; Kumar, Shiva

    2014-09-01

    Nonlinear Schrödinger equation (NLSE) is solved using different split-step Fourier methods (SSFM). The uniform step size distribution is traditionally utilized and the efficiency of the scheme can be improved by using the adaptive step sizes. One scheme of using the adaptive step size is the local error method, which updates the step size based on the local error of the current step. In this paper, a novel scheme which combines the minimum area mismatch (MAM) and the local error method is proposed. The MAM method can be used to find the optimal step size distribution based on minimizing the area mismatch between the ideal effective nonlinear coefficient curve and its stepwise approximation. The local error is a criterion to choose the total number of steps per span. The simulation results show that the proposed scheme outperforms the schemes using uniform step size and adaptive step size.

  6. Ultrasensitive refractive index sensor based on a Mach-Zehnder interferometer created in twin-core fiber.

    PubMed

    Li, Zhengyong; Liao, Changrui; Wang, Yiping; Dong, Xiaopeng; Liu, Shen; Yang, Kaiming; Wang, Qiao; Zhou, Jiangtao

    2014-09-01

    We proposed and experimentally demonstrated a twin-core fiber (TCF)-based Mach-Zehnder interferometer (MZI) to develop an ultrasensitive refractive index (RI) sensor. This fiber MZI was constructed by splicing a short section of TCF between two sections of single mode fibers. A microchannel was drilled through one core of the TCF by means of femtosecond laser micromachining to create one arm of the proposed interferometer, and the other core worked as the second arm. Such a fiber interferometer exhibits an ultrahigh RI sensitivity of -10981??nm/RIU and a low temperature cross-sensitivity of 3.96×10(-6)??RIU/°C. Moreover, the ultra-compact device size and all-fiber configuration make it very suitable for highly sensitive RI sensing at precise location. PMID:25166054

  7. Split-step Fourier transform method in modeling of pulse propagation in dispersive nonlinear optical fibers

    Microsoft Academic Search

    M. Aleshams; A. Zarifkar; M. H. Sheikhi

    2005-01-01

    The propagation of pulses in optical fibers is described by the generalized nonlinear Schrodinger equation (GNLSE), which takes into account the fiber losses, nonlinear effects, and higher-order chromatic dispersion. The GNLSE is a partial differential equation, whose order depends on the nonlinear and dispersion effects. As this equation is not amenable to analytical solution, the use of numerical integration techniques

  8. Detection of external refractive index change with high sensitivity using long-period gratings in photonic crystal fiber

    Microsoft Academic Search

    Yinian Zhu; Zonghu He; Henry Du

    2008-01-01

    We report that the proposed long-period gratings (LPGs), which were fabricated in an endlessly single-mode photonic crystal fiber (ESM-PCF) via point-by-point residual stress relaxation utilizing focused CO2 laser irradiation, exhibit a high sensitivity to variations in the external refractive index, with an identified shifting of attenuation band as large as 4.4pm for 1×10?5 change in the surrounding refractive index over

  9. Analysis of graded-index optical fibers by the spectral parameter power series method

    NASA Astrophysics Data System (ADS)

    Castillo-Pérez, Raúl; Kravchenko, Vladislav V.; Torba, Sergii M.

    2015-02-01

    The spectral parameter power series (SPPS) method is a recently introduced technique (Kravchenko 2008 Complex Var. Elliptic Equ. 53 775–89, Kravchenko and Porter 2010 Math. Methods Appl. Sci. 33 459–68) for solving linear differential equations and related spectral problems. In this work we develop an approach based on the SPPS for analysis of graded-index optical fibers. The characteristic equation of the eigenvalue problem for calculation of guided modes is obtained in an analytical form in terms of SPPS. Truncation of the series and consideration in this way of the approximate characteristic equation gives us a simple and efficient numerical method for solving the problem. Comparison with the results obtained by other available techniques reveals clear advantages for the SPPS approach, in particular, with regards to accuracy. Based on the solution of the eigenvalue problem, parameters describing the dispersion are analyzed as well.

  10. Adaptive higher-order split-step Fourier algorithm for simulating lightwave propagation in optical fiber

    Microsoft Academic Search

    Xueming Liu

    2009-01-01

    In this paper, we propose an adaptive step-size control algorithm for solving nonlinear Schrödinger’s equations. The proposed algorithm has a fourth-order local accuracy and is a system-independent rule for adjusting the step sizes. This algorithm has two potential advantages, an automatic step adjustment mechanism and higher-order accuracy. A test example shows that, by comparing to the fixed step-size method and

  11. Low-complexity logarithmic step-size-based filtered digital backward propagation algorithm for compensating fiber transmission impairments

    NASA Astrophysics Data System (ADS)

    Asif, Rameez; Lin, Chien-Yu; Holtmannspoetter, Michael; Schmauss, Bernhard

    2012-01-01

    We have investigated a new method to reduce the complexity of the digital backward propagation algorithm (DBP). A logarithmic step-size based split-step Fourier method (SSFM) is investigated in this paper to compensate fiber transmission impairments i.e. chromatic dispersion (CD) and non-linearities (NL) in dual-polarization quadrature phase shift keying (DP-QPSK) system. The algorithm is numerically investigated for coherently-detected multiple channel DP-QPSK system over 2000km (25 spans) standard single mode fiber (SMF-28) with un-compensated transmission link. The algorithm is numerically evaluated for: (a) 20 channel 56Gbit/s (14GBaud) with 25GHz channel spacing; (b) 10 channel 112Gbit/s (28GBaud) with 50GHz channel spacing and (c) 5 channel 224Gbit/s (56GBaud) with 100GHz channel spacing. Each simulation configuration has the bandwidth occupancy of 500GHz and a total transmission capacity of 1.12Tbit/s. The logarithmic DBP algorithm (L-DBP) shows efficient results as compared to the conventional DBP method based on modified SSFM (M-DBP). The results depict efficient mitigation of CD and NL, therefore improving the non-linear threshold point (NLT) upto 4dB. Furthermore by implementing a low-pass-filter (LPF) in each SSFM step, the required number of DBP stages to compensate fiber transmission impairments can be significantly reduced (multi-span DBP) by 75% as compared to L-DBP and by 50% as compared to M-DBP. The results delineate improved system performance of logarithmic step size based filtered DBP (FL-DBP) both in terms of efficiency and complexity which will be helpful in future deployment of DBP algorithm with real-time signal processing modules for non-linear compensation.

  12. Determining Properties of Fabricated Index-Guiding Photonic Crystal Fibers Using SEM Micrograph and Mode Convergence Algorithm

    Microsoft Academic Search

    Partha Roy Chaudhuri; Sourabh Roy

    2008-01-01

    We develop a method for modeling properties of fabricated (realistic) air-silica photonic crystal fibers (PCFs). Our approach involves extracting the transverse refractive index (RI) profile of the drawn PCF from its scanning electron micrograph on which is operated a precise and fast mode-analysis recipe based on a finite difference (FD) field convergence scheme. From the digitized scaled RI distribution, we

  13. Accurate mode characterization of graded-index multimode fibers for the application of mode-noise analysis

    NASA Astrophysics Data System (ADS)

    Liu, Yueai; Rahman, B. M. A.; Ning, Ya Nong; Grattan, K. T. V.

    1995-03-01

    Guided modes in graded-index multimode optical fibers are accurately analyzed with the vector H-field finite-element method, aided by the use of the WKB method. As a result, exact mode-propagation constants and the corresponding modal eigenfield distributions are provided for the study of the modal noise that is due to the mode-coupling effect.

  14. Partial power recovery of bend-induced loss using a hybrid index-guiding photonic crystal fiber

    E-print Network

    Vlachos, Kyriakos G.

    Partial power recovery of bend-induced loss using a hybrid index-guiding photonic crystal fiber, National Hellenic Research Foundation, 48 Vas. Constantinou Ave., 16635, Athens, Greece Photonic crystal of wavelengths. References [1] T. A. Birks, J. C. Knight, and P. St.J. Russell, "Endlessly single-mode photonic

  15. Single-step method for fiber-optic probe-based full-range spectral domain optical coherence tomography.

    PubMed

    Min, Eun Jung; Shin, Jun Geun; Lee, Jae Hwi; Yasuno, Yoshiaki; Lee, Byeong Ha

    2013-07-20

    We propose a single-step method appropriated for a fiber-optic probe-based full-range spectral domain optical coherence tomography (OCT). The fiber-optic probe was scanned over a sample with a magnetically driven actuator. In the reference arm, a phase shift of ?/2 was applied during two neighbor axial scanning, from which the complex spectral interferogram was directly reconstructed. Since the complex-conjugate-free OCT image is obtained by doing just one Fourier transform on the complex interferogram, obtaining the full-range image is simple in algorithm and effective in computation time. Some full-range images of biological samples created with the proposed method are presented and the processing time is analyzed. PMID:23872759

  16. Long period fiber grating based refractive index sensor with enhanced sensitivity using Michelson interferometric arrangement

    NASA Astrophysics Data System (ADS)

    Singh, Amit

    2015-06-01

    The long period fiber grating (LPFG) is widely used as a sensor due to its high sensitivity and resolution. However, the broad bandwidth of the attenuation bands formed by the mode coupling between the fundamental core mode and the cladding modes constitutes a difficulty when the device is used as a conventional sensor. To overcome this limitation, a Michelson interferometer-type sensor configuration has been developed, using an LPFG grating pair formed by coating a mirror at the distal end of the LPFG. This sensor configuration is more convenient to use and is able to overcome the limitations of the single LPFG based sensor as the shifts in the attenuation bands being more easily detectable due to the formation of the sharp spectral fringe pattern in the LPFG based Michelson interferometer. In this work, I studied the LPFG based Michelson interferometer as the refractive index sensor and discussed the sensitivity enhancement of the LPFG based Michelson interferometer as a refractive index sensor by employing higher order cladding modes and by reducing the cladding radius. The results demonstrated the HE17 mode with a cladding radius of 62.5 ?m, in the range of surrounding refractive index (SRI) of 1-1.45, and its resonant peak showed a wavelength shift of 26.99 nm/RIU. When the cladding region was further reduced to 24 ?m, the resonant peak showed a wavelength shift of 569.88 nm/RIU, resulting in a sensitivity enhancement of nearly 21 times. However, as the cladding region was etched further, then the HE17 order cladding mode and higher mode would be cut off. Therefore, the implementation of high sensitivity for SRI sensing with the reduced cladding in the LPFG based Michelson interferometer is dependent on the proper combination of the cladding radius and cladding mode order.

  17. New approach to the measurement of the nonlinear refractive index of short (<25 m) lengths of silica and erbium-doped fibers

    Microsoft Academic Search

    Hernando Garcia; Anthony M. Johnson; Ferdinand A. Oguama; Sudhir Trivedi

    2003-01-01

    The nonlinear refractive index n2 of silica fiber (24 m) and erbium-doped fiber (10 m) is measured to within an accuracy of 5% by use of time-delayed photorefractive beam coupling of intense 53-ps, 1.064-mum pulses that experience self-phase modulation in the fibers. The resultant induced grating autocorrelation response yields a value of n2\\/Aeff and a calibration standard for the fiber.

  18. Enhanced interferometric methods for investigation of refractive index distribution changes along tapering structure in photonic crystal fibers

    NASA Astrophysics Data System (ADS)

    Jaroszewicz, Leszek R.; Kujawi?ska, Ma?gorzata; Stasiewicz, Karol; Siwicki, Bart?omiej; Wójcik, S?awomir; Mar?, Pawe?

    2010-09-01

    The paper presents the analysis and enhancements of interferometric methods which may provide better quality projections for tomographic, in-line determination of geometry and refractive index distribution changes along classical as well as photonic crystal fiber tapering structure. The method and system provides high optical resolution and sensitivity for determination of refractive index changes. It also provides the possibility of investigation of structures with and without circular symmetry of refractive index distribution. In the paper the interferometric tomography method in Mach-Zehnder interferometer configuration is applied and the measurements of classical and photonics crystal fibers are presented. The analysis of future use of in-line digital holographic method coupled with a variety of techniques for enhanced phase reconstruction is performed.

  19. Refractive-index insensitive long-period fiber gratings point-by-point inscribed by CO2 laser for fiber sensors and lasers

    NASA Astrophysics Data System (ADS)

    Han, Qun; Lan, Xinwei; Huang, Jie; Wei, Tao; Gao, Zhan; Xiao, Hai

    2012-02-01

    This paper reports a long-period fiber gratings(LPFG) fabricated on a double-clad fiber (DCF) by the CO2 laser point-by-point technique. The LPFG is tested by measuring temperature and refractive index (RI) of different liquids. The results show that the LPFG inscribed on the DCF has no measurable sensitivity to external RI but has a high sensitivity for temperature. The measured temperature sensitivity is ~0.11 nm/oC, about 10 times higher than that of conventional FBGs. Such LPFGs can be used as a modulator in fiber lasers or temperature/strain sensors in applications where the surrounding RI is prone to variation, such as simultaneous measurement of the temperature and RI of chemical reactions.

  20. Influence of the nature of optical fibers in materials treatment by Nd:YAG lasers

    Microsoft Academic Search

    F. Lemoine; J. M. Jouvard; H. Andrzejewski; D. F. Grevey

    1996-01-01

    Of great interest in the use of Nd:YAG lasers is the possibility of transporting the beam inside an optical fiber. Pointed out in this work is the lower degradation of the beam quality using an optical fiber rather than using mirrors. The influence of the nature of the fiber (graded- and step-index fiber) on the focal point diameter, the position.

  1. Understanding High-Power Fiber-Optic Laser Beam Delivery

    Microsoft Academic Search

    Boyd V. Hunter; Keng H. Leong; Carl B. Miller; James F. Golden; Robert D. Glesias; Patrick J. Laverty

    ABSTRACT Fiber-optic beam,delivery is commonly,used on industrial laser systems. This article examines the conditions for the optimal propagation of high power beams through optical fibers. Beam quality effects by step and gradient index fibers of different lengths are considered. The differences between the diverging beam from a fiber and the beam at focus and on the fiber face are illustrated.

  2. Lensed plastic optical fiber employing concave end filled with high-index resin

    Microsoft Academic Search

    Hajime Sakata; Aya Imada

    2002-01-01

    We propose an optical coupling scheme that uses a fiber-end lens to achieve efficient coupling of the plastic optical fiber with a light source and with a detector. Transparent resin filled in the concave end of the fiber is fixed by surface tension to form a biconvex lens that is automatically positioned relative to the fiber core. A simple ray-matrix

  3. Improved Optical Fiber Chemical Sensors

    NASA Technical Reports Server (NTRS)

    Egalon, Claudio O.; Rogowski, Robert S.

    1994-01-01

    Calculations, based on exact theory of optical fiber, have shown how to increase optical efficiency sensitivity of active-core, step-index-profile optical-fiber fluorosensor. Calculations result of efforts to improve efficiency of optical-fiber chemical sensor of previous concept described in "Making Optical-Fiber Chemical Sensors More Sensitive" (LAR-14525). Optical fiber chemical detector of enhanced sensitivity made in several configurations. Portion of fluorescence or chemiluminescence generated in core, and launched directly into bound electromagnetic modes that propagate along core to photodetector.

  4. Volatile profile of cashew apple juice fibers from different production steps.

    PubMed

    Nobre, Ana Carolina de Oliveira; de Almeida, Áfia Suely Santos da Silva; Lemos, Ana Paula Dajtenko; Magalhães, Hilton César Rodrigues; Garruti, Deborah Dos Santos

    2015-01-01

    This study aimed to determine the volatile profile of cashew apple fibers to verify which compounds are still present after successive washings and thus might be responsible for the undesirable remaining cashew-like aroma present in this co-product, which is used to formulate food products like vegetarian burgers and cereal bars. Fibers were obtained from cashew apple juice processing and washed five times in an expeller press. Compounds were analyzed by the headspace solid-phase micro extraction technique (HS-SPME) and gas chromatography-mass spectrometry (GC-MS), using a DB-5 column. Sensory analysis was also performed to compare the intensity of the cashew-like aroma of the fibers with the original juice. Altogether, 80 compounds were detected, being esters and terpenes the major chemical classes. Among the identified substances, 14 were classified as odoriferous in the literature, constituting the matrix used in the Principal Component Analysis (PCA). Odoriferous esters were substantially reduced, but many compounds were extracted by the strength used in the expeller press and remained until the last wash. Among them are the odoriferous compounds ethyl octanoate, ?-dodecalactone, (E)-2-decenal, copaene, and caryophyllene that may contribute for the mild but still perceptible cashew apple aroma in the fibers that have been pressed and washed five times. Development of a deodorization process should include reduction of pressing force and stop at the second wash, to save water and energy, thus reducing operational costs and contributing to process sustainability. PMID:26023940

  5. Achieving comparable global accuracy in the split-step Fourier simulation of optical fiber communication channel

    Microsoft Academic Search

    Qun Zhang; Liudong Xing; Michael Cheng; Imn Hayee

    2005-01-01

    Optical communication system design is a challenging task because there is no general analytical solution for the nonlinear and dispersive fiber channel. Although there has been progress in analytical channel models such as Volterra series model and other variants of the perturbation model, numerical simulations are still extensively used in channel characterization, equalization and system design. In this paper, the

  6. First steps in developing a multimetric macroinvertebrate index for the Ohio River

    USGS Publications Warehouse

    Applegate, J.M.; Baumann, P.C.; Emery, E.B.; Wooten, M.S.

    2007-01-01

    The causes of degradation of aquatic systems are often complex and stem from a variety of human influences. Comprehensive, multimetric biological indices have been developed to quantify this degradation and its effect on aquatic communities, and measure subsequent recovery from anthropogenic stressors. Traditionally, such indices have concentrated on small-to medium-sized streams. Recently, however, the Ohio River Fish Index (ORFIn) was created to assess biotic integrity in the Ohio River. The goal of the present project was to begin developing a companion Ohio River multimetric index using benthic macroinvertebrates. Hester-Dendy multiplate samplers were used to evaluate benthic macroinvertebrate assemblages in relation to a gradient of water quality disturbance, represented by varying distances downstream of industrial and municipal wastewater outfalls in the Ohio River. In August 1999 and 2000, samplers were set every 100 m downstream of outfalls (12 outfalls in 1999, 22 in 2000) for 300-1000 m, as well as at upstream reference sites. Candidate metrics (n = 55) were examined to determine which have potential to detect changes in water quality downstream of outfalls. These individual measures of community structure were plotted against distance downstream of each outfall to determine their response to water quality disturbance. Values at reference and outfall sites were also compared. Metrics that are ecologically relevant and showed a response to outfall disturbance were identified as potentially valuable in a multimetric index. Multiple box plots of index scores indicated greater response to outfall disturbance during periods of low-flow, and longitudinal river-wide trends. Evaluation of other types of anthropogenic disturbance, as well as continued analysis of the effects of chemical water quality on macroinvertebrate communities in future years will facilitate further development of a multimetric benthic macroinvertebrate index to evaluate biotic integrity in the Ohio River. Copyright ?? 2007 John Wiley & Sons, Ltd.

  7. Temperature and index insensitive strain sensor based on a photonic crystal fiber in line Mach-Zehnder interferometer

    NASA Astrophysics Data System (ADS)

    Zheng, Jiarong; Yan, Peiguang; Yu, Yongqin; Ou, Zhilong; Wang, Jishun; Chen, Xue; Du, Chenlin

    2013-06-01

    Mach-Zehnder interferometer strain sensors made from pieces of photonic crystal fiber spliced to standard single mode fibers are fabricated with different lengths. High strain sensitivity of 2.1 pm/?? at 1550 nm is achieved with the length of 45 mm. The interference is induced by the core mode and the high order core mode due to the special air hole structure of PCF, which is independent of the surrounding refractive index. The temperature sensitivity (˜13.24 pm/°C) is relatively low. This structure is good in avoiding cross sensitivity in strain measurement and is fabricated with a simple process and low cost.

  8. A high-quality Mach-Zehnder interferometer fiber sensor by femtosecond laser one-step processing.

    PubMed

    Zhao, Longjiang; Jiang, Lan; Wang, Sumei; Xiao, Hai; Lu, Yongfeng; Tsai, Hai-Lung

    2011-01-01

    During new fiber sensor development experiments, an easy-to-fabricate simple sensing structure with a trench and partially ablated fiber core is fabricated by using an 800 nm 35 fs 1 kHz laser. It is demonstrated that the structure forms a Mach-Zehnder interferometer (MZI) with the interference between the laser light passing through the air in the trench cavity and that in the remained fiber core. The fringe visibilities are all more than 25 dB. The transmission spectra vary with the femtosecond (fs) laser ablation scanning cycle. The free spectral range (FSR) decreases as the trench length increases. The MZI structure is of very high fabrication and sensing repeatability. The sensing mechanism is theoretically discussed, which is in agreement with experiments. The test sensitivity for acetone vapor is about 10(4) nm/RIU, and the temperature sensitivity is 51.5 pm/°C at 200 ? 875 °C with a step of 25 °C. PMID:22346567

  9. Optimization of the split-step Fourier method in modeling optical-fiber communications systems

    Microsoft Academic Search

    Oleg V. Sinkin; Ronald Holzlöhner; John Zweck; Curtis R. Menyuk

    2003-01-01

    We studied the efficiency of different implementations of the split-step Fourier method for solving the nonlinear Schrödinger equation that employ different step-size selection criteria. We compared the performance of the different implementations for a variety of pulse formats and systems, including higher order solitons, collisions of soliton pulses, a single-channel periodically stationary dispersion-managed soliton system, and chirped return to zero

  10. High power fiber optic laser beam delivery.

    SciTech Connect

    Leong, K. H.; Hunter, B. V.; Technology Development

    1996-05-01

    Fiber-optic beam delivery is commonly used on industrial laser systems. This article examines the conditions for the optimal propagation of high power beams through optical fibers. Beam quality effects by step and gradient index fibers of different lengths are considered. The differences between the diverging beam from a fiber and the beam at focus and on the fiber face are illustrated. Estimates are provided of the worst-case beam quality to be expected from fibers. Guidelines are also provided for the selection of beam delivery components based on the limitations of the optical system and the tasks to be performed.

  11. SPR based fiber optic sensor for refractive index sensing with enhanced detection accuracy and figure of merit in visible region

    NASA Astrophysics Data System (ADS)

    Mishra, Akhilesh K.; Mishra, Satyendra K.; Gupta, Banshi D.

    2015-06-01

    We, theoretically, propose a surface plasmon resonance (SPR) based indium tin oxide (ITO)-silver (Ag) coated fiber optic sensing probe for refractive index sensing in visible regime of the electromagnetic spectrum. A comparative study of ITO+Ag coated probe with Ag coated probe and with ITO coated probe using their respective optimized film thicknesses is carried out. We show that the proposed probe is endowed with the better sensitivity characteristic of ITO and better detection accuracy (DA) characteristic of Ag, and can sense change in refractive index with enhanced DA and figure of merit (FOM) in the visible region.

  12. Numerical and experimental investigation of long-period gratings in photonic crystal fiber for refractive index sensing of gas media.

    PubMed

    Tian, Fei; He, Zonghu; Du, Henry

    2012-02-01

    We have used the finite-difference frequency-domain (FDFD) method to simulate the core mode to cladding mode couplings in long-period gratings (LPGs) in photonic crystal fiber (PCF). Four sets of LPG-PCF have been fabricated with respective periodicities of 590, 540, 515, and 490 ?m, resulting in corresponding resonance wavelengths (RWs) of 1241, 1399, 1494, and 1579 nm. We show both theoretically and experimentally that the longer the RW, the more sensitive the LPG-PCF is to the index change in Ar. We demonstrate a robust sensitivity of 517 nm per refractive index unit using the LPG-PCF at 1579 nm RW. PMID:22297359

  13. Polymer optical fiber tapering without the use of external heat source and its application to refractive index sensing

    NASA Astrophysics Data System (ADS)

    Ujihara, Hiroki; Hayashi, Neisei; Minakawa, Kazunari; Tabaru, Marie; Mizuno, Yosuke; Nakamura, Kentaro

    2015-07-01

    We perform a pilot trial of the highly convenient taper fabrication of perfluorinated graded-index polymer optical fibers. Instead of conventional external heating, we utilize internal heating caused by high-power propagating light (500 mW in this experiment). An approximately 4-mm-long section of a polymer fiber is tapered, and the outer diameter of the ?2-mm-long waist around its midpoint is approximately 200 µm, which is quite uniform with a standard deviation of 4.3 µm. The polymer fiber taper fabricated by this technique is shown to be capable of generating evanescent waves and thus measuring the refractive indices of liquids from 1.333 to 1.410.

  14. Phase-stepping fiber-optic projected fringe system for surface topography measurements

    NASA Technical Reports Server (NTRS)

    Mercer, Carolyn R. (inventor); Beheim, Glenn (inventor)

    1992-01-01

    A projected fringe interferometer for measuring the topography of an object is presented. The interferometer periodically steps the phase angle between a pair of light beams emanating from a common source. The steps are pi/2 radians (90 deg) apart, and at each step a video image of the fringes is recorded and stored. Photodetectors measure either the phase and theta of the beams or 2(theta). Either of the measures can be used to control one of the light beams so that the 90 deg theta is accurately maintained. A camera, a computer, a phase controller, and a phase modulator established closed-loop control of theta. Measuring the phase map of a flat surface establishes a calibration reference.

  15. Carbohydrate Intake, Glycemic Index, Glycemic Load, and Dietary Fiber in Relation to Risk of Stroke in Women

    Microsoft Academic Search

    Kyungwon Oh; Frank B. Hu; Eunyoung Cho; Kathryn M. Rexrode; Meir J. Stampfer; JoAnn E. Manson; Simin Liu; Walter C. Willett

    2005-01-01

    The associations of dietary carbohydrate, glycemic index, and glycemic load with stroke risk were examined among 78,779 US women who were free of cardiovascular disease and diabetes in 1980 and completed a food frequency questionnaire. During an 18-year follow-up, 1,020 stroke cases were documented (including 515 ischemic and 279 hemorrhagic). In analyses adjusting for nondietary risk factors and cereal fiber,

  16. Content analysis of uterine cervix images: initial steps towards content based indexing and retrieval of cervigrams

    NASA Astrophysics Data System (ADS)

    Gordon, Shiri; Zimmerman, Gali; Long, Rodney; Antani, Sameer; Jeronimo, Jose; Greenspan, Hayit

    2006-03-01

    This work is motivated by the need for visual information extraction and management in the growing field of medical image archives. In particular the work focuses on a unique medical repository of digital cervicographic images ("Cervigrams") collected by the National Cancer Institute (NCI) in a longitudinal multi-year study carried out in Guanacaste, Costa Rica. NCI together with the National Library of Medicine (NLM) is developing a unique Web-based database of the digitized cervix images to study the evolution of lesions related to cervical cancer. Such a database requires specific tools that can analyze the cervigram content and represent it in a way that can be efficiently searched and compared. We present a multi-step scheme for segmenting and labeling regions of medical and anatomical interest within the cervigram, utilizing statistical tools and adequate features. The multi-step structure is motivated by the large diversity of the images within the database. The algorithm identifies the cervix region within the image. It than separates the cervix region into three main tissue types: the columnar epithelium (CE), the squamous epithelium (SE), and the acetowhite (AW), which is visible for a short time following the application of acetic acid. The algorithm is developed and tested on a subset of 120 cervigrams that were manually labeled by NCI experts. Initial segmentation results are presented and evaluated.

  17. A quarter-wave phase-stepping algorithm for fiber-optic electronic speckle pattern interferometry using zero-crossing triggers

    Microsoft Academic Search

    Hyoung-Jun Park; Minho Song

    2006-01-01

    An efficient phase-stepping method for the use in fiber-optic electronic speckle pattern interferometry is proposed. A fiber-optic Michelson interferometer is phase-modulated, and the zero-crossing points of a back-reflected interference signal, that have consecutive pi phase difference, are used to trigger the charged-coupled device camera to capture specklegrams with pi\\/2 phase difference. A phase error of less than 3 mrad with

  18. Modified split-step Fourier method for the numerical simulation of soliton amplification in erbium-doped fibers with forward-propagating noise

    Microsoft Academic Search

    J. R. Costa; C. R. Paiva; A. M. Barbosa

    2001-01-01

    Using a modified version of the split-step Fourier method, we analyze the effect of noise on soliton propagation inside erbium-doped fiber amplifiers. In fact, noise from forward-propagating amplified spontaneous emission, associated with a Markov immigration process, is included in the analysis of soliton amplification. Moreover, this algorithm accounts for the real spectral gain profile of the fiber amplifier. The frequency

  19. MIMO equalization with adaptive step size for few-mode fiber transmission systems.

    PubMed

    van Uden, Roy G H; Okonkwo, Chigo M; Sleiffer, Vincent A J M; de Waardt, Hugo; Koonen, Antonius M J

    2014-01-13

    Optical multiple-input multiple-output (MIMO) transmission systems generally employ minimum mean squared error time or frequency domain equalizers. Using an experimental 3-mode dual polarization coherent transmission setup, we show that the convergence time of the MMSE time domain equalizer (TDE) and frequency domain equalizer (FDE) can be reduced by approximately 50% and 30%, respectively. The criterion used to estimate the system convergence time is the time it takes for the MIMO equalizer to reach an average output error which is within a margin of 5% of the average output error after 50,000 symbols. The convergence reduction difference between the TDE and FDE is attributed to the limited maximum step size for stable convergence of the frequency domain equalizer. The adaptive step size requires a small overhead in the form of a lookup table. It is highlighted that the convergence time reduction is achieved without sacrificing optical signal-to-noise ratio performance. PMID:24514973

  20. Modal dispersion, pulse broadening and maximum transmission rate in GRIN optical fibers encompass a central dip in the core index profile

    NASA Astrophysics Data System (ADS)

    El-Diasty, Fouad; El-Hennawi, H. A.; El-Ghandoor, H.; Soliman, Mona A.

    2013-12-01

    Intermodal and intramodal dispersions signify one of the problems in graded-index multi-mode optical fibers (GRIN) used for LAN communication systems and for sensing applications. A central index dip (depression) in the profile of core refractive-index may occur due to the CVD fabrication processes. The index dip may also be intentionally designed to broaden the fundamental mode field profile toward a plateau-like distribution, which have advantages for fiber-source connections, fiber amplifiers and self-imaging applications. Effect of core central index dip on the propagation parameters of GRIN fiber, such as intermodal dispersion, intramodal dispersion and root-mean-square broadening, is investigated. The conventional methods usually study optical signal propagation in optical fiber in terms of mode characteristics and the number of modes, but in this work multiple-beam Fizeau interferometry is proposed as an inductive but alternative methodology to afford a radial approach to determine dispersion, pulse broadening and maximum transmission rate in GRIN optical fiber having a central index dip.

  1. Ambient refractive index-independent bending vector sensor based on seven-core photonic crystal fiber using lateral offset splicing.

    PubMed

    Ou, Zhilong; Yu, Yongqin; Yan, Peiguang; Wang, Jishun; Huang, Quandong; Chen, Xue; Du, Chenlin; Wei, Huifeng

    2013-10-01

    A novel, simple, and compact optical fiber directional bending vector sensor based on Mach-Zehnder interferometer (MZI) is proposed and experimentally demonstrated. The device consists of a piece of seven-core photonic crystal fiber (PCF) sandwiched between two single mode fibers (SMFs) with a lateral offset splicing joint that covering two cores of PCF. Bending sensitivity of the seven-core PCF based MZI is changed by an axial rotation angle, which shows its capacity for recognizing positive and negative directions. Within a curvature range of -7.05 m-1 to 7.05 m-1, the calculated bending sensitivities of two resonant central wavelengths with opposite fiber orientations are 1.232 nm/m-1 and 1.174 nm/m-1, respectively. This novel MZI is formed by invoking interference between the LP01-like supermode and other higher order supermodes in the core, which leads to insensitive to ambient refractive index (ARI). We have also investigated the transmission characteristics of the sensor with the temperature change. PMID:24104292

  2. High Sensitive Temperature Sensor Using a Liquid-core Optical Fiber with Small Refractive Index Difference Between Core and Cladding Materials

    PubMed Central

    Xu, Yonghao; Chen, Xianfeng; Zhu, Yu

    2008-01-01

    An intensive temperature sensor based on a liquid-core optical fiber has been demonstrated for the measuring the temperature of the environment. The core of fiber is filled with a mixture of toluene and chloroform in order to make the refractive index of the liquid-core and the cladding of the fiber close. The experiment shows that a temperature sensitivity of about 5 dB/K and a tunable temperature range (from 20 °C to 60 °C) can be achieved. Based on the dielectric-clad liquid core fiber model, a simulation was carried out and the calculated results were in good accord with the experimental measurement.

  3. New phospho-tellurite glasses with optimization of transition temperature and refractive index for hybrid microstructured optical fibers

    NASA Astrophysics Data System (ADS)

    Duan, Zhongchao; Tong, Hoang Tuan; Liao, Meisong; Cheng, Tonglei; Erwan, Motillon; Suzuki, Takenobu; Ohishi, Yasutake

    2013-10-01

    The glass formation and compositional dependences of glass thermal properties and optical properties were investigated in TeO2-ZnO-Na2O-P2O5 system. The refractive index at 1.55 ?m and glass transition temperature varied in a wide range from 1.513 to 2.036 and from 265 °C to 376 °C by controlling of the TeO2/P2O5 and ZnO/Na2O content, respectively. These properties enable phospho-tellurite glasses with large freedom in designing and fabrication of hybrid microstructured optical fiber. The structures of glasses were investigated by Raman spectra to understand their dependence of structure on composition. Using the present glasses, some hybrid microstructured optical fibers with various dispersion profiles were designed.

  4. Optimized graded index two-mode optical fiber with low DMD, large A(eff) and low bending loss.

    PubMed

    Sato, Kiminori; Maruyama, Ryo; Kuwaki, Nobuo; Matsuo, Shoichiro; Ohashi, Masaharu

    2013-07-15

    An optimized two-mode optical fiber (TMF) with the graded index (GI) profile is designed and fabricated. We clarify an appropriate region of GI-TMF satisfying DMD = 0 ps/km, the large effective area A(eff), and the low bending loss for LP(11) at 1550 nm. According to our fiber design, GI-TMF is successfully fabricated to have the large effective area A(eff) of 150 ?m(2) for LP(01) mode, and low DMD below 36 ps/km including zero in the C-band. We expect that our design GI-TMF is suitable for MDM and can reduce MIMO-DSP complexity. PMID:23938473

  5. Fiber optics: A brief introduction

    SciTech Connect

    Gruchalla, M.E.

    1989-01-01

    A basic introduction into the principles of fiber optics is presented. A review of both the underlying physical principles and the individual elements of typical fiber-optic systems are presented. The optical phenomenon of total internal reflection is reviewed. The basic construction of the optical fiber is presented. Both step-index and graded-index fiber designs are reviewed. Multimode and single-mode fiber constructions are considered and typical performance parameters given. Typical optical-fiber bandwidth and loss characteristics are compared to various common coaxial cables, waveguides, and air transmission. The constructions of optical-fiber cables are reviewed. Both loose-tube and tightly-buffered designs are considered. Several optical connection approaches are presented. Photographs of several representative optical connectors are included. Light Emitting Diode and Laser Diode emitters for fiber-optic applications are reviewed, and some advantages and shortcomings of each are considered. The phenomenon of modal noise is briefly explained. Both PIN and Avalanche photodetectors are reviewed and their performance parameters compared. Methods of data transmission over optical fiber are introduced. Principles of Wavelength, Frequency, and Time Division Multiplexing are briefly presented. The technology of fiber-optic sensors is briefly reviewed with basic principles introduced. The performance of a fiber-optic strain sensor is included as a practical example. 7 refs., 10 figs.

  6. A Reliable Split-Step Fourier Method for the Propagation Equation of Ultra-Fast Pulses in Single-Mode Optical Fibers

    SciTech Connect

    Deiterding, Ralf [ORNL; Glowinski, R. [University of Houston, Houston; Oliver, Hilde [ORNL; Poole, Stephen W [ORNL

    2013-01-01

    The extension to the split-step Fourier method (SSFM) for Schrodinger-type pulse propagation equations that we propose in this article is designed with the accurate simulation of pulses in the femto-second regime in single-mode communication fibers in mind. We show that via an appropriate operator splitting scheme, Kerr nonlinearity and the self-steepening and stimulated Raman scattering terms can be combined into a single sub-step consisting of an inhomogeneous quasilinear first-order hyperbolic system for the real-valued quantities intensity and phase. First- and second-order accurate shock-capturing upwind schemes have been developed specifically for this nonlinear sub-step, which enables the accurate and oscillation-free simulation of signals under the influence of Raman scattering and extreme self-steepening with the SSFM. Benchmark computations of ultra-fast Gaussian pulses in fibers with strong nonlinearity demonstrate the superior approximation properties of the proposed approach.

  7. Nonlinear pulse reshaping in a designed erbium-doped fiber amplifier with a multicladded index profile

    NASA Astrophysics Data System (ADS)

    Bose, Navonil; Ghosh, Dipankar; Mukherjee, Sampad; Basu, Mousumi

    2013-08-01

    A multicladded normally dispersive erbium-doped fiber amplifier (ND-EDFA) is designed for a short length to operate at the wavelength of 1550 nm with a dispersion of -6.5 ps/km nm and parabolic pulse generation through the proposed fiber is studied. The proposed ND-EDFA shows a flattened gain spectrum in C-band. The nonlinear Schrödinger equation is solved numerically in presence of fiber gain, nonlinearity, and dispersion to investigate the pulse propagation through the proposed fiber. While continuous wave (CW) sources are considered, parabolic self-similar pulses with structure factor of 0.072 are created at suitable values of optimum fiber length when input pulse properties and fiber parameters are optimized accordingly. Side by side with a low repetition rate laser source, the pulse propagation equation is controlled by the gain dispersion term and dipole relaxation time, such that the evolution of Gaussian pulses may lead to nonparabolic regime. The effects of pulse parameters like power level, pulse width, and dipole relaxation time on the propagation of input Gaussian pulses through the so-designed ND-EDFA are investigated. Our results depict that the pulses with same input energy reshape into exactly parabolic shape for CW laser source or nonparabolic profile for a laser source with low repetition rate.

  8. New approach to the measurement of the nonlinear refractive index of short (<25 m) lengths of silica and erbium-doped fibers

    NASA Astrophysics Data System (ADS)

    Garcia, Hernando; Johnson, Anthony M.; Oguama, Ferdinand A.; Trivedi, Sudhir

    2003-10-01

    The nonlinear refractive index n2 of silica fiber (24 m) and erbium-doped fiber (10 m) is measured to within an accuracy of 5% by use of time-delayed photorefractive beam coupling of intense 53-ps, 1.064-?m pulses that experience self-phase modulation in the fibers. The resultant induced grating autocorrelation response yields a value of n2/Aeff and a calibration standard for the fiber. A phase shift of the order of 0.19? can be detected and is limited only by laser amplitude fluctuations. A unique advantage of this technique is its ability to measure n2 accurately in short lengths (z <= 25 m) of fiber, whereas other approaches typically use much longer lengths of fiber (z >= 100 m).

  9. Fabrication of double cladding structure in optical multimode fibers using plasma channeling excited by a high-intensity femtosecond laser

    Microsoft Academic Search

    Sung-Hak Cho; Hiroshi Kumagai; Katsumi Midorikawa; Minoru Obara

    1999-01-01

    Refractive index modification in multimode optical fibers was first demonstrated using the plasma channeling excited by a high-intensity femtosecond (110 fs) Ti: sapphire laser (?p=790 nm). The refractive index modification induced in a pure silica multimode step-index fiber with a 100\\/110 ?m core\\/cladding diameter reached a length of approximately 9?10 mm from the input surface of the optical fiber with

  10. Numerical analysis and experimental investigation of highly sensitive photonic crystal fiber long-period grating refractive index sensor

    NASA Astrophysics Data System (ADS)

    He, Zonghu; Zhu, Yinian; Ka?ka, Ji?í; Du, Henry

    2007-09-01

    In this paper, we present the numerical analyses of modal coupling properties and resonance spectral response of longperiod gratings (LPGs) in solid-core photonic crystal fibers (PCFs) with respect to their sensitivity to refractive indices of measurands in the air channels using a full-vectoral mode solver combined with frequency-domain method. The calculated results show that the wavelength resonance of a PCF-LPG can be extremely sensitive to the refractive index change. The PCF-LPG refractive index sensors, inscribed by residual stress relaxation using a scanning CO II laser, are also experimentally investigated in terms of resonance shift with the PCF-LPG structure filled with sodium chloride (NaCl) solutions at concentrations ranging from 0-26% (w/w). The spectral features were greatly improved by inscribing the LPG structure in PCF prefilled with water. The PCF-LPG sensors are shown to be able to detect the change of ~10 -7 refractive index unit (RIU) in the index range of 1.33 to 1.35, in a good agreement with the numerical simulation.

  11. Dispersion optimization of photonic crystal fiber long-period gratings for a high-sensitivity refractive index sensing

    NASA Astrophysics Data System (ADS)

    Kanka, Jiri

    2011-05-01

    Photonic crystal fiber long-period gratings (PCF-LPGs) operating near the phase-matching turning point to achieve high sensitivity to the refractive index of gas and liquid analytes infiltrated into cladding air holes are designed by numerical optimization. The vectorial finite element method is employed for the modal analysis of an index-guiding PCF and the calculation of the phase matching curves. The geometrical parameters of PCF (pitch and diameter of air holes arranged in a periodic triangular array) are optimized by using the down-hill simplex technique to engineer the dispersion of modes coupled by a LPG to obtain the turning point in the phase-matching curve at a desired wavelength for a given analyte refractive index. The resonant wavelength is subsequently extremely sensitive to the analyte refractive index, however, its large shifts can be detected with a substantially reduced resolution because the resonance dip in the LPG transmission spectrum is very broad. On the other hand, the broad resonance provides a broadband operation of a PCF-LPG sensor and its high sensitivity to the refractive index can still be achieved by relying on changes in the coupling strength (and consequently in the transmission loss) rather than in the resonant wavelength of LPG. We consider coupling between the fundamental core mode and the first-order symmetric cladding mode. We also explore an alternative approach based on coupling between the fundamental core mode and the fundamental space-filling mode instead of the individual cladding mode. The PCF-LPG structure optimized for refractive-index sensing is also assessed for label-free biosensing.

  12. Effects of phosphor distribution and step-index remote configuration on the performance of white light-emitting diodes.

    PubMed

    Chiang, Chung-Hao; Tsai, Hung-Yi; Zhan, Ting-Shi; Lin, Han-Yu; Fang, Ying-Chien; Chu, Sheng-Yuan

    2015-06-15

    Phosphor-converted white light-emitting diodes (pc-WLEDs) are fabricated by combining CaSi2O2N2:Eu2+ and Ca2Si5N8:Eu2+ phosphors with a blue chip. Experimental results demonstrate that placing the red phosphor layer above the yellow one (Y down/R up) yields the highest luminous efficiency, making it the preferable phosphor distribution for pc-WLEDs rather than Y up/R down. This finding suggests that the extent of overlap between the emission spectrum of short-emission-wavelength phosphors and the excitation spectrum of long-emission-wavelength phosphors and their luminous efficacy of radiation should be taken into account simultaneously when studying the optical characteristics of pc-WLEDs. Compared to common pc-WLEDs with silicone gel as the remote layer, the proposed step-index remote configuration exhibits superior luminous efficiency because of reduced total internal reflection and Fresnel loss. PMID:26076273

  13. Fiber

    MedlinePLUS

    ... broccoli, spinach, and artichokes legumes (split peas, soy, lentils, etc.) almonds Look for the fiber content of ... salsa, taco sauce, and cheese for dinner. Add lentils or whole-grain barley to your favorite soups. ...

  14. Distinct docking and stabilization steps of the Pseudopilus conformational transition path suggest rotational assembly of type IV pilus-like fibers.

    PubMed

    Nivaskumar, Mangayarkarasi; Bouvier, Guillaume; Campos, Manuel; Nadeau, Nathalie; Yu, Xiong; Egelman, Edward H; Nilges, Michael; Francetic, Olivera

    2014-05-01

    The closely related bacterial type II secretion (T2S) and type IV pilus (T4P) systems are sophisticated machines that assemble dynamic fibers promoting protein transport, motility, or adhesion. Despite their essential role in virulence, the molecular mechanisms underlying helical fiber assembly remain unknown. Here, we use electron microscopy and flexible modeling to study conformational changes of PulG pili assembled by the Klebsiella oxytoca T2SS. Neural network analysis of 3,900 pilus models suggested a transition path toward low-energy conformations driven by progressive increase in fiber helical twist. Detailed predictions of interprotomer contacts along this path were tested by site-directed mutagenesis, pilus assembly, and protein secretion analyses. We demonstrate that electrostatic interactions between adjacent protomers (P-P+1) in the membrane drive pseudopilin docking, while P-P+3 and P-P+4 contacts determine downstream fiber stabilization steps. These results support a model of a spool-like assembly mechanism for fibers of the T2SS-T4P superfamily. PMID:24685147

  15. Distinct docking and stabilization steps of the pseudopilus conformational transition path suggest rotational assembly of type IV pilus-like fibers

    PubMed Central

    Nivaskumar, Mangayarkarasi; Bouvier, Guillaume; Campos, Manuel; Nadeau, Nathalie; Yu, Xiong; Egelman, Edward H.; Nilges, Michael; Francetic, Olivera

    2014-01-01

    SUMMARY The closely related bacterial type II secretion (T2S) and type IV pilus (T4P) systems are sophisticated machines that assemble dynamic fibers promoting protein transport, motility or adhesion. Despite their essential role in virulence, the molecular mechanisms underlying helical fiber assembly remain unknown. Here we use electron microscopy and flexible modeling to study conformational changes of PulG pili assembled by the Klebsiella oxytoca T2SS. Neural network analysis of 3900 pilus models suggested a transition path towards low-energy conformations driven by progressive increase in fiber helical twist. Detailed predictions of inter-protomer contacts along this path were tested by site-directed mutagenesis, pilus assembly and protein secretion analyses. We demonstrate that electrostatic interactions between adjacent protomers (P-P+1) in the membrane drive pseudopilin docking, while P-P+3 and P-P+4 contacts determine downstream fiber stabilization steps. These results support a new model of a spool-like assembly mechanism for fibers of the T2SS-T4P superfamily. PMID:24685147

  16. Refractive-Index Sensing With Inline Core-Cladding Intermodal Interferometer Based on Silicon Nitride Nano-Coated Photonic Crystal Fiber

    Microsoft Academic Search

    Mateusz Smietana; Daniel Brabant; Wojtek J. Bock; Predrag Mikulic; Tinko Eftimov

    2012-01-01

    This paper presents a modification of the refractive-index (RI) response of an intermodal interferometer based on photonic crystal fiber (PCF) using a thin plasma-deposited silicon nitride (SiN $_{\\\\rm x}$) overlay with a high refractive index. We show that the film overlay can effectively change the distribution of the cladding modes and thus tune the RI sensitivity of the interferometer. Thanks

  17. Long Period Gratings in Random Hole Optical Fibers for Refractive Index Sensing

    PubMed Central

    Wang, Ke; Pickrell, Gary

    2011-01-01

    We have demonstrated the fabrication of long period gratings in random hole optical fibers. The long period gratings are fabricated by a point-by-point technique using a CO2 laser. The gratings with a periodicity of 450 ?m are fabricated and a maximum coupling efficiency of ?9.81 dB has been achieved. Sensing of different refractive indices in the surrounding mediums is demonstrated by applying standard liquids with refractive indices from 1.400 to 1.440 to the long period grating. PMID:22319368

  18. Long period gratings in random hole optical fibers for refractive index sensing.

    PubMed

    Wang, Ke; Pickrell, Gary

    2011-01-01

    We have demonstrated the fabrication of long period gratings in random hole optical fibers. The long period gratings are fabricated by a point-by-point technique using a CO(2) laser. The gratings with a periodicity of 450 ?m are fabricated and a maximum coupling efficiency of -9.81 dB has been achieved. Sensing of different refractive indices in the surrounding mediums is demonstrated by applying standard liquids with refractive indices from 1.400 to 1.440 to the long period grating. PMID:22319368

  19. Record 5.3 Gbit\\/s transmission over 50m 1mm core diameter graded-index plastic optical fiber

    Microsoft Academic Search

    D. Visani; C. M. Okonkwo; S. Loquai; H. Yang; Y. Shi; H. P. A. van den Boom; A. M. H. Ditewig; G. Tartarini; B. Schmauss; S. Randel; A. M. J. Koonen; E. Tangdiongga

    2010-01-01

    We report multi-Gbit\\/s capacity in 1-mm diameter graded index plastic optical fiber exploiting low-cost eye safe compliant transceivers. Transmission rates between 5.3 and 7.6 Gbit\\/s are achieved for lengths between 10 and 50 m using DMT.

  20. Making Optical-Fiber Chemical Detectors More Sensitive

    NASA Technical Reports Server (NTRS)

    Rogowski, Robert S.; Egalon, Claudio O.

    1993-01-01

    Calculations based on exact theory of optical fiber shown how to increase optical efficiency and sensitivity of active-cladding step-index-profile optical-fiber fluorosensor using evanescent wave coupling. Optical-fiber fluorosensor contains molecules fluorescing when illuminated by suitable light in presence of analyte. Fluorescence coupled into and launched along core by evanescent-wave interaction. Efficiency increases with difference in refractive indices.

  1. Refractive index sensing characteristics of dual resonance long period gratings in bare and metal-coated D-shaped fibers.

    PubMed

    Mani Tripathi, Saurabh; Marin, Emmanuel; Kumar, Arun; Meunier, Jean-Pierre

    2009-11-01

    We present a theoretical study of the ambient refractive index sensing characteristics of long period gratings in bare and metal-coated D-shaped fibers. An equivalent rectangular core waveguide method based on the first-order perturbation theory has been used to study the modal behavior of the waveguide. Power coupling corresponding to dual resonance in both cases has been investigated, and an optimum metal thickness giving maximum sensitivity has been found to exist. The study shows that the dual resonances can be shifted to lower wavelengths by increasing (decreasing) the metal thickness (core to flat surface separation). Further, an optimum combination of metal thickness and core to flat surface separation, corresponding to maximum sensitivity, has been presented for different cladding modes and their relative performance has been discussed. It has been shown theoretically that detection of refractive index changes as small as 1.67x10(-7) RIU in the ambient region is possible using the optimized parameters. The study should find application in realizing highly sensitive biochemical sensors. PMID:19881646

  2. Substrate temperature effect on the refractive index and a two-step film method to detect small inhomogeneities in optical films

    Microsoft Academic Search

    Fachun Lai; Ming Li; Kang Chen; Haiqian Wang; Yizhou Song; Yousong Jiang

    2005-01-01

    Nb2O5 films were deposited by a reactive magnetron sputtering technique. The average refractive index was found to increase with the rise of substrate temperature. Modulated interference transmittance spectra were observed in the two-step films, which were prepared by stopping the deposition process in the middle of the designed sputtering time, and then, after a full cooling down to room temperature,

  3. Single-mode microstructured optical fiber for the middle infrared.

    PubMed

    Butvina, Leonid N; Sereda, Olesya V; Dianov, Eugeny M; Lichkova, Ninel V; Zagorodnev, Vladimir N

    2007-02-15

    Microstructured crystalline optical fiber from silver halides is described. Both experimental and theoretical evidences are presented to establish that the fiber is effectively single mode at wavelength 10.6 micro m with numerical aperture NA=0.16 and optical losses of approximately 2 dB/m. Crystalline microstructured optical fibers offer key advantages over step-index optical fibers from silver halide crystals. The wide transmission range of wavelengths 2-20 micro m provides great potential for applications in spectroscopy and for the development of a range of new crystalline-based nonlinear optical fibers. PMID:17356644

  4. Thulium fiber laser and application development

    NASA Astrophysics Data System (ADS)

    Shah, Lawrence; Gaida, Christian; Gebhardt, Martin; Sincore, Alex; Bradford, Joshua D.; Gehlich, Nils; Mingareev, Ilya; Richardson, Martin

    2014-06-01

    Within the past 10 years, thulium (Tm)-doped fiber lasers have emerged as a flexible platform offering high average power as well as high peak power. Many of the benefits and limitations of Tm:fiber lasers are similar to those for ytterbium (Yb)-doped fiber lasers, however the ~2 µm emission wavelength posses unique challenges in terms of laser development as well as several benefits for applications. In this presentation, we will review the progress of laser development in CW, nanosecond, picosecond, and femtosecond regimes. As a review of our efforts in the development of power amplifiers, we will compare large mode area (LMA) stepindex and photonic crystal fiber (PCF) architectures. In our research, we have found Tm-doped step index LMA fibers to offer relatively high efficiency and average powers at the expense of fundamental mode quality. By comparison, Tm-doped PCFs provide the largest mode area and quasi diffraction-limited beam quality however they are approximately half as efficient as step-index fibers. In terms of defense related applications, the most prominent use of Tm:fiber lasers is to pump nonlinear conversion to the mid-IR such as supercontinuum generation and optical parametric oscillators/amplifiers (OPO/A). We have recently demonstrated Tm:fiber pumped OPOs which generate ~28 kW peak power in the mid-IR. In addition, we will show that Tm:fiber lasers also offer interesting capabilities in the processing of semiconductors.

  5. Photonic bandgap fibers

    Microsoft Academic Search

    S. E. Barkou; J. Broeng; A. Bjarklev

    1999-01-01

    Photonic bandgap fibers are described using a new Kagome cladding structure. These fibers may potentially guide light in low-index regions. Such fibers offer new dispersion properties, and large design flexibility

  6. Symmetrized Split-Step Fourier Scheme to Control Global Simulation Accuracy in Fiber-Optic Communication Systems

    Microsoft Academic Search

    Qun Zhang; M. Imran Hayee

    2008-01-01

    Analytical expressions involving both system parameters and step-size are proposed to represent the local simulation error for the symmetrized split-step Fourier (SSSF) simulation method. This analytical expression can be used for a step-size selection rule to achieve comparable local simulation accuracy for SSSF simulations. This can lead to computational savings since there is no waste of computation in each simulation

  7. Optimal Design of Dispersion Filter for Time-Domain Split-Step Simulation of Pulse Propagation in Optical Fiber

    Microsoft Academic Search

    Yang Zhu; David V. Plant

    2012-01-01

    The nonlinear Schrödinger equation can be solved by split-step methods, where in each step, linear dispersion and nonlinear effects are treated separately. This paper considers the optimal design of an FIR filter as the time-domain implementation for the linear part. The objective is to minimize the integral of the squared error between the FIR frequency response and the desired dispersion

  8. Sol-gel preparation of hydrophobic silica antireflective coatings with low refractive index by base/acid two-step catalysis.

    PubMed

    Cai, Shuang; Zhang, Yulu; Zhang, Hongli; Yan, Hongwei; Lv, Haibing; Jiang, Bo

    2014-07-23

    Hydrophobic antireflective coatings with a low refractive index were prepared via a base/acid-catalyzed two-step sol-gel process using tetraethylorthosilicate (TEOS) and methyltriethoxysilane (MTES) as precursors, respectively. The base-catalyzed hydrolysis of TEOS leads to the formation of a sol with spherical silica particles in the first step. In the second step, the acid-catalyzed MTES hydrolysis and condensation occur at the surface of the initial base-catalyzed spherical silica particles, which enlarge the silica particle size from 12.9 to 35.0 nm. By a dip-coating process, this hybrid sol gives an antireflective coating with a refractive index of about 1.15. Moreover, the water contact angles of the resulted coatings increase from 22.4 to 108.7° with the increases of MTES content, which affords the coatings an excellent hydrophobicity. A "core-shell" particle growth mechanism of the hybrid sol was proposed and the relationship between the microstructure of silica sols and the properties of AR coatings was investigated. PMID:24979297

  9. An adaptive Fourier Bessel split-step method and variational techniques applied to nonlinear propagation in negative index materials

    Microsoft Academic Search

    P. P. Banerjee; G. Nehmetallah

    2006-01-01

    Starting from a simple dispersion relation that models negative index materials, we derive and develop the underlying partial differential equation for wave propagation in such a medium. In the first part we study the linear characteristics of wave and beam propagation in NIMs. In the second part we heuristically perform a nonlinear extension of the linear partial differential equation by

  10. From zero dispersion to group index matching: How tapering fibers offers the best of both worlds for visible supercontinuum generation

    NASA Astrophysics Data System (ADS)

    Stone, J. M.; Knight, J. C.

    2012-09-01

    We provide an experimental study of the nonlinear optical effects which can be enhanced in order to produce visible supercontinua in photonic crystal fibers. We examine individual uniform fibers and discuss the physical origins of the resulting supercontinua. We then examine tapered supercontinuum fibers which exploit the advantages of our individual uniform fibers at different points along the length of the taper. We demonstrate reproducible control of taper shape.

  11. Excitation of Single-mode Circular Core Parabolic Index Fiber by Laser Diode via Upside Down Tapered Hemispherical Microlens on the Tip of the Fiber: Estimation of Coupling Efficiency by Application of ABCD Matrix Formalism

    NASA Astrophysics Data System (ADS)

    Das, Bishuddhananda; Maiti, Anup Kumar; Gangopadhyay, Sankar

    2014-06-01

    The ABCD matrix prescribed for a upside down tapered hemispherical microlens end drawn from a parabolic index circular core fiber is used to formulate analytical expression of coupling efficiency of excitation of this optical device by a laser diode. In our analysis, we assume Gaussian field distribution for both the source and the fiber. For maximum coupling efficiency, the lens transmitted spot size of the source should match with the fiber spot size. In our investigations, we employ two different laser diodes emitting wavelengths 1.3 ?m and 1.5 ?m respectively. It is found that the wavelength 1.5 ?m is more efficient in the context of present coupling optics. Our formalism predicts the concerned coupling optics excellently and the execution of our formalism requires little computations. This simple but accurate technique is expected to benefit the system designers and packagers concerned with optimum launch optics.

  12. Simultaneous measurement of external refractive index and temperature based on long-period-grating-inscribed Sagnac interferometer and fiber Bragg grating

    NASA Astrophysics Data System (ADS)

    Gao, Peng; Chen, Xiuyan; Feng, Wenjiang

    2012-10-01

    A compact Sagnac interferometer with a long-period grating (LPG) inscribed in a polarization-maintaining fiber (PMF-LPG) and a fiber Bragg grating (FBG) is proposed. The PMF-LPG is intrinsically sensitive to the external refractive index (ERI) and temperature, whereas the FBG is only sensitive to temperature. Simultaneous measurement of the ERI and temperature can be achieved by detecting wavelength shifts in the interference patterns of the Sagnac interferometer and the FBG. Because a Sagnac interference structure is used, a high ERI sensitivity of -21.07 nm/refractive index unit in measurement range 1.33-1.43 is obtained, which is about three times higher than for the normal LPG ERI sensor.

  13. Numerical analysis of GeO2-concentration effects in arc-induced long-period fiber gratings under external refractive-index changes

    NASA Astrophysics Data System (ADS)

    Guzman-Ramos, Valentin; Ceballos-Herrera, Daniel E.; Selvas-Aguilar, Romeo

    2014-03-01

    We present a numerical analysis of the response of arc-induced long-period fiber gratings (LPFGs) under ambient refractive-index changes using standard fibers with SiO2 as cladding material and different GeO2 concentration in the SiO2-GeO2 doped core. We obtain that the LPFG-sensitivity is increased using lower GeO2 concentrations and it follows a parabolic behavior. Also, we identify two linear regimes using an external index of 1.37: for GeO2 concentrations between 2 and 3.5 mol %, the LPFG-sensitivity changes with a rate of 3.614 nm per mole fraction of GeO2, while for higher concentrations the sensitivity changes with a rate of 1.39 nm/mol %. Additionally, for fibers with 2 mol% of GeO2, the sensitivity calculated is comparable to this obtained in previous works using corrugated and tapered LPFGs in SMF28 fibers. These results are of interest for the design of improved LPFG-sensors.

  14. Effect of temperature on optical fiber transmission. [for spacecraft communication

    NASA Technical Reports Server (NTRS)

    Yeung, W. F.; Johnston, A. R.

    1978-01-01

    Results are presented concerning the effects of temperature on the transmission properties of various optical fibers including a silicone plastic clad, an acrylic plastic clad, and CVD step-index fibers both with and without polyurethane jackets. Results are presented for the normalized transmitted power vs temperature, the index of refraction vs temperature, and induced attenuation coefficients vs temperature. The data show that the intrinsic transmission of a CVD fiber is independent of temperature over the -110 to +150 C range. Plastic clad fused silica fibers are subject to transmission losses at lower temperatures due to changes in the optical index of the cladding polymer. Acrylic-clad and plastic-clad silica fibers also show transmission losses at lower temperatures, but to lesser extents.

  15. Enhanced atom guiding in metal-coated, hollow-core optical fibers

    Microsoft Academic Search

    Herschel S. Pilloff

    1997-01-01

    A new-type of atom guiding structure has been analyzed. It consists of a hollow-core optical fiber (step index) which is not clad, but instead has a metal coating on its outer lateral surface. It will be shown that this structure produces the maximum evanescent field in the hollow region of the fiber and guiding can be accomplished with lower power

  16. Real-Time implementation of a 1.25-Gbit\\/s DMT transmitter for robust and Low-cost LED-based plastic optical fiber applications

    Microsoft Academic Search

    Sian Lee; F. Breyer; D. Cardenas; S. Randel; T. Koonen

    2009-01-01

    Real-time implementation of a DMT transmitter in FPGA is demonstrated for low-cost, standard 1-mm step-index plastic optical fiber applications based on commercial resonant-cavity LED and large-diameter (540 mum) photodiode.

  17. Fabrication of single-mode waveguide structure in optical multimode fluoride fibers using self-channeled plasma filaments excited by a femtosecond laser

    Microsoft Academic Search

    S.-H. Cho; H. Kumagai; K. Midorikawa

    2003-01-01

    A permanent structure of a single-mode waveguide in optical multimode fluoride fibers was first fabricated using a self-channeled plasma filament excited by a femtosecond (110-fs) Ti:sapphire laser (? p=800 nm). The photoinduced refractive-index modification in a multimode step-index fluoride glass (ZBLAN) fiber with a 100\\/110-µm core\\/cladding diameter reached a length of approximately 12–15 mm from the input surface of the optical fiber,

  18. Very high intensity fiber transmission systems

    SciTech Connect

    Setchell, R.E.

    1995-12-31

    Various applications are currently motivating interest in the transmission of very high laser intensities through optical fibers. As intensities within a fiber are increased, however, laser breakdown or laser-induced fiber damage will eventually occur and interrupt fiber transmission. For a number of years we have been studying these effects during the transmission of Q-switched, Nd/YAG laser pulses through step-index, multimode, fused-silica fiber. We have found that fiber transmission is often limited by a plasma-forming breakdown occurring at the fiber entrance face. This breakdown results in subtle surface modifications that can leave the surface more resistant to further breakdown or damage events. Catastrophic fiber damage can also occur as a result of a number of different mechanisms, with damage appearing at fiber end faces, within the initial ``entry`` segment of the fiber path, and at other internal sites due to effects related to the particular fiber routing. An overview of these past observations is presented, and issues requiring further study are identified.

  19. Mode size converter between high-index-contrast waveguide and cleaved single mode fiber using SiON as intermediate material.

    PubMed

    Jia, Lianxi; Song, Junfeng; Liow, Tsung-Yang; Luo, Xianshu; Tu, Xiaoguang; Fang, Qing; Koh, Sing-Chee; Yu, Mingbin; Lo, Guoqiang

    2014-09-22

    High-index-contrast (HIC) waveguide such as Si and Si3N4 has small mode size enabling compact integration. However, the coupling loss with single mode fiber is also remarkable owning to the mode mismatching. Therefore, mode size converter, as the interface between HIC waveguide and optical fiber, takes an important role in the field of integrated optics. The material with refractive index (RI) between HIC waveguide and optical fiber can be used as a bridge to reduce the mode mismatching loss. In this letter, we employ silicon oxynitride (SiON) with RI about 1.50 as the intermediate material and optimize the structure of the SiON waveguide to match with cleaved single mode fiber and HIC waveguide separately. Combined with inverse taper and suspended structure, the mismatching loss is reduced and the dependence to the dimension of the structure is also released. The coupling loss is 1.2 and 1.4 dB/facet for TE and TM mode, respectively, with 3 dB alignment tolerance of ± 3.5 ?m for Si(3)N(4) waveguide with just 200 nm-wide tip. While for Si waveguide, a critical dimension of 150 nm is applied due to the higher index contrast than Si(3)N(4) waveguide. Similar alignment tolerance is realized with coupling loss about 1.8 and 2.1 dB/facet for TE and TM mode. The polarization dependence loss (PDL) for both platforms is within 0.5 dB. PMID:25321831

  20. Is the Kidney Donor Risk Index a step forward in the assessment of deceased donor kidney quality?

    PubMed

    Lee, Alison P K; Abramowicz, Daniel

    2015-08-01

    The allocation of deceased donor kidneys has become more complex because of the increasing spectrum of donors and recipients age and comorbidities. Several scoring systems have been proposed to evaluate the donor quality of deceased donor kidneys, based on clinical, pathological or combined parameters to predict the risk of renal allograft failure. Nonetheless, besides the dichotomous extended criteria donor (ECD) score, none of the others have been used in clinical practice because of numerous reasons, ranging from lack of robust validation to the technical challenges associated with the evaluation of donor biopsies. Recently, the Kidney Donor Risk Index (KDRI) and Profile Index (KDPI) were introduced in the USA as a refined version of the ECD score. This scoring system is based on 10 donor factors, therefore providing a finely granulated evaluation of donor quality without the need of a kidney biopsy.Here, we review the advantages and drawbacks of the main scoring systems, and we describe the components of the KDRI and KDPI. It is an easily accessible online tool, based solely on donor factors readily available at the moment of the donor offer. Importantly, the KDPI has also been made part of the 'longevity matching' allocation in the USA, where the best kidneys are allocated to the recipients with the longest predicted post-transplant survival. The KDRI should provide us with a robust qualitative evaluation of deceased donor quality, and therefore will probably play a role in deceased donor kidney allocation policies across Europe in the near future. Hopefully, the KDRI and the KDPI should help transplant programmes to better allocate the scarce resource of deceased donor kidneys. PMID:25282158

  1. Glycemic index, glycemic load, dietary carbohydrate, and dietary fiber intake and risk of liver and biliary tract cancers in Western Europeans

    PubMed Central

    Fedirko, V.; Lukanova, A.; Bamia, C.; Trichopolou, A.; Trepo, E.; Nöthlings, U.; Schlesinger, S.; Aleksandrova, K.; Boffetta, P.; Tjønneland, A.; Johnsen, N. F.; Overvad, K.; Fagherazzi, G.; Racine, A.; Boutron-Ruault, M. C.; Grote, V.; Kaaks, R.; Boeing, H.; Naska, A.; Adarakis, G.; Valanou, E.; Palli, D.; Sieri, S.; Tumino, R.; Vineis, P.; Panico, S.; Bueno-de-Mesquita, H. B(as).; Siersema, P. D.; Peeters, P. H.; Weiderpass, E.; Skeie, G.; Engeset, D.; Quirós, J. R.; Zamora-Ros, R.; Sánchez, M. J.; Amiano, P.; Huerta, J. M.; Barricarte, A.; Johansen, D.; Lindkvist, B.; Sund, M.; Werner, M.; Crowe, F.; Khaw, K. T.; Ferrari, P.; Romieu, I.; Chuang, S. C.; Riboli, E.; Jenab, M.

    2013-01-01

    Background The type and quantity of dietary carbohydrate as quantified by glycemic index (GI) and glycemic load (GL), and dietary fiber may influence the risk of liver and biliary tract cancers, but convincing evidence is lacking. Patients and methods The association between dietary GI/GL and carbohydrate intake with hepatocellular carcinoma (HCC; N = 191), intrahepatic bile duct (IBD; N = 66), and biliary tract (N = 236) cancer risk was investigated in 477 206 participants of the European Prospective Investigation into Cancer and Nutrition cohort. Dietary intake was assessed by country-specific, validated dietary questionnaires. Hazard ratios and 95% confidence intervals were estimated from proportional hazard models. HBV/HCV status was measured in a nested case–control subset. Results Higher dietary GI, GL, or increased intake of total carbohydrate was not associated with liver or biliary tract cancer risk. For HCC, divergent risk estimates were observed for total sugar = 1.43 (1.17–1.74) per 50 g/day, total starch = 0.70 (0.55–0.90) per 50 g/day, and total dietary fiber = 0.70 (0.52–0.93) per 10 g/day. The findings for dietary fiber were confirmed among HBV/HCV-free participants [0.48 (0.23–1.01)]. Similar associations were observed for IBD [dietary fiber = 0.59 (0.37–0.99) per 10 g/day], but not biliary tract cancer. Conclusions Findings suggest that higher consumption of dietary fiber and lower consumption of total sugars are associated with lower HCC risk. In addition, high dietary fiber intake could be associated with lower IBD cancer risk. PMID:23123507

  2. Studies of plastic optical fibers for applications in high-speed communication networks

    Microsoft Academic Search

    Gang Jiang

    1998-01-01

    In this thesis, we report the results of our experimental and theoretical studies of the optical properties of large core step index (SI) plastic optical fibers (POF) and graded index (GI) POFs. A set of criteria and analyses of physical parameters are developed in context to the major issues of POF applications in short-distance communication systems. Analyses are presented to

  3. Phase-shift formed in a tapered long period fiber grating and its application to simultaneous measurements of temperature and refractive-index

    NASA Astrophysics Data System (ADS)

    Hishiki, Keisuke; Li, Hongpu

    2013-09-01

    A novel approach to calibrate a phase-shift formed in a long-period fiber grating (LPG) is proposed and successfully demonstrated, which is based on the use of either a power- or a wavelength-interrogation technique to the loss-peak existed in the transmission spectrum of the phase-shifted LPG. Moreover, in this study, by tapering a LPG with CO2 laser, phase-shift is successfully created at central part of the LPG. Finally, base on the use of this kind of phase-shifted LPG, a simultaneous measurement for the temperature and the surrounding refractive index has been proposed and experimentally demonstrated.

  4. Low-loss hybrid fiber with zero dispersion wavelength shifted to 1 ?m

    NASA Astrophysics Data System (ADS)

    Aleshkina, Svetlana S.; Likhachev, Mikhail E.; Senatorov, Andrei K.; Bubnov, Mikhail M.; Salaganskii, Mikhail Yu.; Guryanov, Alexei N.

    2014-03-01

    We propose a novel cylindrically symmetric hybrid fiber design that allows combining properties of the both fibers guiding light due to total internal reflection (low optical losses) and photonic bandgap fibers (anomalous dispersion at 1 ?m). Refractive index profile of these fibers consist of the only few layers: low-index core (ncore-nsilica>0) surrounded with one or more high-index ring layers (nhigh-ncore>0), a depressed layer (ndepress-nsilica<0) and silica cladding. Operating mode is one of the high-order modes (depending on high-index ring layers number) with intensity maximum at fiber axis. Because the other modes (including the fundamental mode LP01) are guided in the high-index ring layer(s) the hybrid mode can be easily excited by splicing hybrid fiber and standard single-mode (?~1?m) step-index fiber with appropriate mode field diameter. Moreover method of achievement of asymptotically singlemode regime of light propagation (suppression of the high-index ring layer modes) has been proposed. The main idea of it is doping narrow strong absorbing layer where hybrid mode has intensity of electric field closed to zero. Furthermore we have considered possibility to increase anomalous dispersion of the hybrid fiber (up to 100 ps/nm km) by usage more complicated refractive index profile with two high-index ring layers. In this work we have fabricated the technologically simplest hybrid fiber with the only one high-index layer. The hybrid LP02 core mode had dispersion of 13 ps/(nm km) and optical loss of about 6 dB/km. Propagation of chirped pulses through the fabricated hybrid fiber allowed us to compress them from 8ps to 330fs.

  5. High-brightness power delivery for fiber laser pumping: simulation and measurement of low-NA fiber guiding

    NASA Astrophysics Data System (ADS)

    Yanson, Dan; Levy, Moshe; Peleg, Ophir; Rappaport, Noam; Shamay, Moshe; Dahan, Nir; Klumel, Genady; Berk, Yuri; Baskin, Ilya

    2015-02-01

    Fiber laser manufacturers demand high-brightness laser diode pumps delivering optical pump energy in both a compact fiber core and narrow angular content. A pump delivery fiber of a 105 ?m core and 0.22 numerical aperture (NA) is typically used, where the fiber NA is under-filled to ease the launch of laser diode emission into the fiber and make the fiber tolerant to bending. At SCD, we have developed multi-emitter fiber-coupled pump modules that deliver 50 W output from a 105 ?m, 0.15 NA fiber at 915, 950 and 976 nm wavelengths enabling low-NA power delivery to a customer's fiber laser network. In this work, we address the challenges of coupling and propagating high optical powers from laser diode sources in weakly guiding step-index multimode fibers. We present simulations of light propagation inside the low-NA multimode fiber for different launch conditions and fiber bend diameters using a ray-racing tool and demonstrate how these affect the injection of light into cladding-bounded modes. The mode filling at launch and source NA directly limit the bend radius at which the fiber can be coiled. Experimentally, we measure the fiber bend loss using our 50 W fiber-coupled module and establish a critical bend diameter in agreement with our simulation results. We also employ thermal imaging to investigate fiber heating caused by macro-bends and angled cleaving. The low mode filling of the 0.15 NA fiber by our brightness-enhanced laser diodes allows it to be coiled with diameters down to 70 mm at full operating power despite the low NA and further eliminates the need for mode-stripping at fiber combiners and splices downstream from our pump modules.

  6. Radiation Effects and Propagation in Optical Fibers and Components

    Microsoft Academic Search

    Subhash Ganpatrao Gedam

    1987-01-01

    The power series expansion method was used to solve the wave equation in step-index optical fiber. The cut off frequencies were calculated using 200 coefficients. The cutoff frequencies of TM modes were found to differ from those of TE modes. This difference, which is the error due to the approximations made, was calculated as a function of the relative refractive

  7. Simulation-guided design and fabrication of long-period gratings in photonic crystal fiber as refractive index transduction platform for multi-parameter sensing

    NASA Astrophysics Data System (ADS)

    He, Zonghu

    2011-12-01

    Fiber optic sensing technology based on conventional, all-solid optical fiber has been broadly used for chemical and biological sensing and detection. The advent of photonic crystal fiber (PCF) offers transformative opportunities due to its unique waveguiding and microstructural features. Incorporating long period gratings (LPG) in PCF has the potential to further catapult LPG-PCF based sensing technology in terms of greatly improved sensing capabilities and significantly expanded field of applications. This doctoral dissertation aims to synergistically integrate LPG and index guiding PCF as refractive index transduction platform to explore its potential for multi-parameter sensing and measurements. The phase matching conditions, core mode to cladding mode coupling, and power overlap were theoretically simulated to aid in the design and fabrication of the LPG-PCF platform using CO2 laser. For sensing of aqueous solutions, we developed a novel means of LPG fabrication while maintaining a steady liquid flow in the PCF air channels. This approach greatly improves the quality and reproducibility of the fabrication process. More importantly, it helps preserve the general resonance coupling condition when an aqueous analyte solution is probed. We have theoretically predicted and experimentally achieved a sensitivity of ˜10-7 refractive index unit using our fabricated LPG-PCF platform due to the strong overlap between the cladding mode evanescent field and the analyte within the PCF air channels. For label-free biosensing, we integrated the LPG-PCF with a home-build microfluidic flow cell that can be optically coupled with the sensing platform while allowing continuous flow of the reagents. As a result, we have demonstrated the ability to monitor a series of surface binding events in situ. Our LPG-PCF is able to consistently detect monolayer biomolecular binding events with a measured resonance wavelength shift of about 0.75 nm per nanometer thick layer formed. Overall, theoretically and experimentally, we have shown that LPG-PCF represents a powerful refractive index transduction platform that can be used for sensing and measurements of multiple parameters. We have clearly shown that LPG-PCF has the potential to be a viable alternative to the surface plasmon resonance-based commercial refractometers for affinity-based biological measurements.

  8. Fiber Optics

    NSDL National Science Digital Library

    SFGate: SBC and Microsofthttp://sfgate.com/cgi-bin/article.cgi?file=/c/a/2004/06/23/MNGVR7AI711.DTLSBC Communications Inc.http://www.sbc.com/gen/press-room?pid=5838How Stuff Works: How Fiber Optics Workhttp://electronics.howstuffworks.com/fiber-optic.htmFiber Optic Reference Guide: A Brief Historyhttp://www.fiber-optics.info/fiber-history.htmPC World: Has Your Broadband Had Its Fiber?http://www.pcworld.com/news/article/0,aid,117684,00.aspTelephony Onlinehttp://telephonyonline.com/ar/telecom_breaking_meg_barrier/index.htmThis article from SFGate reports on the recent negotiations between SBC and Microsoft (1) and the implications of the new technology for Internet and television access. This website from SBC (2) provides video footage and background information on their initiative called Project Lightspeed. This initiative is based largely on fiber technology, which is described further on this website from How Stuff Works (3). This website (4) provides a brief history of fiber optics technology along with links to sections on the applications of fiber optics and more basics on transmission. This article from PC World (5) discusses how fiber optics became a viable option. This article from Telephony Online 6)reviews some of the challenges that remain.

  9. Highly photosensitive polymethyl methacrylate microstructured polymer optical fiber with doped core.

    PubMed

    Sáez-Rodríguez, D; Nielsen, K; Rasmussen, H K; Bang, O; Webb, D J

    2013-10-01

    In this Letter, we report the fabrication of a highly photosensitive, microstructured polymer optical fiber using benzyl dimethyl ketal as a dopant, as well as the inscription of a fiber Bragg grating in the fiber. A refractive index change in the core of at least 3.2×10(-4) has been achieved, providing a grating with a strong transmission rejection of -23 dB with an inscription time of only 13 min. The fabrication method has a big advantage compared to doping step index fiber since it enables doping of the fiber without using extra dopants to compensate for the index reduction in the core introduced by the photosensitive agent. PMID:24081048

  10. Redox-active ionic-liquid-assisted one-step general method for preparing gold nanoparticle thin films: applications in refractive index sensing and catalysis.

    PubMed

    Dinda, Enakshi; Rashid, Md Harunar; Biswas, Mrinmoy; Mandal, Tarun K

    2010-11-16

    We describe a general one-step facile method for depositing gold nanoparticle (GNP) thin films onto any type of substrates by the in situ reduction of AuCl(3) using a newly designed redox-active ionic liquid (IL), tetrabutylphosphonium citrate ([TBP][Ci]). Various substrates such as positively charged glass, negatively charged glass/quartz, neutral hydrophobic glass, polypropylene, polystyrene, plain paper, and cellophane paper are successfully coated with a thin film of GNPs. This IL ([TBP][Ci]) is prepared by the simple neutralization of tetrabutylphosphonium hydroxide with citric acid. We also demonstrate that the [TBP][Ci] ionic liquid can be successfully used to generate GNPs in an aqueous colloidal suspension in situ. The deposited GNP thin films on various surfaces are made up of mostly discrete spherical GNPs that are well distributed throughout the film, as confirmed by field-emission scanning electron microscopy. However, it seems that some GNPs are arranged to form arrays depending on the nature of surface. We also characterize these GNP thin films via UV-vis spectroscopy and X-ray diffractometry. The as-formed GNP thin films show excellent stability toward solvent washing. We demonstrate that the thin film of GNPs on a glass/quartz surface can be successfully used as a refractive index (RI) sensor for different polar and nonpolar organic solvents. The as-formed GNP thin films on different surfaces show excellent catalytic activity in the borohydride reduction of p-nitrophenol. PMID:20942449

  11. Mid-infrared supercontinuum covering the 1.4–13.3??m molecular fingerprint region using ultra-high NA chalcogenide step-index fibre

    NASA Astrophysics Data System (ADS)

    Petersen, Christian Rosenberg; Møller, Uffe; Kubat, Irnis; Zhou, Binbin; Dupont, Sune; Ramsay, Jacob; Benson, Trevor; Sujecki, Slawomir; Abdel-Moneim, Nabil; Tang, Zhuoqi; Furniss, David; Seddon, Angela; Bang, Ole

    2014-11-01

    The mid-infrared spectral region is of great technical and scientific interest because most molecules display fundamental vibrational absorptions in this region, leaving distinctive spectral fingerprints. To date, the limitations of mid-infrared light sources such as thermal emitters, low-power laser diodes, quantum cascade lasers and synchrotron radiation have precluded mid-infrared applications where the spatial coherence, broad bandwidth, high brightness and portability of a supercontinuum laser are all required. Here, we demonstrate experimentally that launching intense ultra-short pulses with a central wavelength of either 4.5??m or 6.3??m into short pieces of ultra-high numerical-aperture step-index chalcogenide glass optical fibre generates a mid-infrared supercontinuum spanning 1.5??m to 11.7??m and 1.4??m to 13.3??m, respectively. This is the first experimental demonstration to truly reveal the potential of fibres to emit across the mid-infrared molecular ‘fingerprint region’, which is of key importance for applications such as early cancer diagnostics, gas sensing and food quality control.

  12. Improved deep UV fiber for medical and spectroscopy applications

    NASA Astrophysics Data System (ADS)

    Khalilov, Valery; Shannon, John; Timmerman, Richard; Geshell, Dale

    2015-03-01

    An effort to demonstrate long term transmission stability in a high -OH synthetic fused silica step index multimode optical fiber optimized for Deep-UV operation, designated as FDP, was successfully completed at Polymicro Technologies. The development achieved significant improvement in long term stability for the 214 and 265nm absorption bands typically associated with solarization effects in fused silica. The improvements were applied to fiber core sizes from 67 to 100µm, a common size range for bundle applications used in medical and spectroscopy. Results of UV degradation measurements for the fiber with minimum 70 hour exposures are presented along with a description of the test protocols.

  13. Glycemic Index, Glycemic Load, and Cereal Fiber Intake and Risk of Type 2 Diabetes in US Black Women

    Microsoft Academic Search

    Supriya Krishnan; Lynn Rosenberg; Martha Singer; Frank B. Hu; Luc Djousse ´; L. Adrienne Cupples; Julie R. Palmer

    2007-01-01

    associated with the risk of diabetes: the IRR for the high- est quintile relative to the lowest was 1.23 (95% confi- dence interval (CI), 1.05-1.44). Cereal fiber intake was inversely associated with risk of diabetes, with an IRR of 0.82 (95% CI, 0.70-0.96) for the highest vs lowest quin- tiles of intake. Stronger associations were seen among women with a

  14. Numerical analysis and experimental investigation of highly sensitive photonic crystal fiber long-period grating refractive index sensor

    Microsoft Academic Search

    Zonghu He; Yinian Zhu; Jirí Kanka; Henry Du

    2007-01-01

    In this paper, we present the numerical analyses of modal coupling properties and resonance spectral response of longperiod gratings (LPGs) in solid-core photonic crystal fibers (PCFs) with respect to their sensitivity to refractive indices of measurands in the air channels using a full-vectoral mode solver combined with frequency-domain method. The calculated results show that the wavelength resonance of a PCF-LPG

  15. Depression of the glycemic index by high levels of ?-glucan fiber in two functional foods tested in type 2 diabetes

    Microsoft Academic Search

    AL Jenkins; DJA Jenkins; U Zdravkovic; P Würsch; V Vuksan

    2002-01-01

    Objectives: To determine the extent to which ?-glucan reduces the glycemic index (GI) of oat products and whether high levels of ?-glucan impair palatability.Design: The study design was an open-label, randomized cross-over study with six treatment segments.Setting: Free-living outpatients.Subjects: Sixteen volunteers with type 2 diabetes (10 men, six women, 61±2 y, body mass index 29±2 kg\\/m2, HbA1c 7.4±0.4%) were recruited

  16. On the application of optical-fiber image scramblers to astronomical spectroscopy

    NASA Astrophysics Data System (ADS)

    Heacox, W. D.

    1986-07-01

    Single, step-index optical fibers, when properly employed, can function as optically efficient image scramblers. Their use as optical feeds for astronomical slit spectrographs can reduce zonal error levels in those instruments by orders of magnitude. As a consequence, the application of optical-fiber couplers to new and existing spectrographs may greatly increase the wavelength metric quality of conventional astronomical spectroscopy. The optical efficiencies of fiber couplers of a few tens of meters in length can be comparable to those of typical coudé mirror trains in the visible portions of the spectrum. Elements of the design of fiber couplers are illustrated by discussion of a currently operational instrument.

  17. Mode mixing in fiber optic oximeter

    NASA Astrophysics Data System (ADS)

    Amirkhanian, Varoujan D.; Lee, Wylie I.

    1990-07-01

    Most catheter based oximeters use optical fiber to deliver two M more colors of light to the blood and collect the reflected lights with another optical fiber. Oxygen saturation of the blood is calculated from intensity of the returned lights. The coupling efficiency of this type of two-fiber sensor depends on the separation of fibers, the numerical aperture (NA) of the fibers, and the launching condition of lights from LED's to the transmission fiber. A micro-optical integrator was designed to combine outputs from two LED's into a multimode step-index fiber pig-tail through a high NA microball lens. The mismatch in the modes of propagation between red and IR lights was corrected by looping and sine-wave bending the fiber before it was coupled to an NA limiting GRIN lens, which also serves as an exit window. A far-field scan of two lights shows these two lights have spatial overlap of 92% or better. The overlap at the tip of the catheter, after it was coupled to the mode mixing pig-tail, is better than 98%. The addition of this simple method of mode-mixing has improved the overlap by nearly 30% and has substantially improved the accuracy of the oximeter, especially when in vitro calibration is used before taking the measurement in blood.

  18. Efficient and short-range light coupling to index-matched liquid-filled hole in a solid-core photonic crystal fiber.

    PubMed

    Gerosa, Rodrigo M; Spadoti, Danilo H; de Matos, Christiano J S; Menezes, Leonardo de S; Franco, Marcos A R

    2011-11-21

    A photonic crystal fiber (PCF) with a section of one of the holes next to the solid core filled with an index-matched liquid is studied. Liquid filling alters the core geometry, which locally comprises the original silica core, the liquid channel and the silica around it. It is demonstrated that when light reaches the filled section, it periodically and efficiently couples to the liquid, via the excitation of a number of modes of the composite core, with coupling lengths ranging from tens to hundreds of microns. The resulting modal-interference-modulated spectrum shows temperature sensitivity as high as 5.35 nm/°C. The proposed waveguide geometry presents itself as an interesting way to pump and/or to probe liquid media within the fiber, combining advantages usually found separately in liquid-filled hollow-core PCFs (high light-liquid overlap) and in solid-core PCFs (low insertion losses). Therefore, pumping and luminescence guiding with a PCF filled with a Rhodamine solution is also demonstrated. PMID:22109496

  19. Slow-light in photonic crystal waveguides/fibers: dispersion tailoring schemes for obtaining a high group index with wide band and low GVD

    NASA Astrophysics Data System (ADS)

    Ren, Liyong; Liang, Jian; Liu, Yu; Ju, Haijuan; Yun, Maojin; Ma, Chengju; Han, Xu; Lin, Xiao; Tomita, Yasuo

    2012-03-01

    Phenomenon of slow light has long been a hot research topic due to its promising and potential applications in communication networks, signal processing, optical sensors and nonlinear interactions. Particularly, photonic crystal devices, being capable of supporting slow-light propagation, are much attractive owing to its room-temperature operation and tunable dispersion features. Among them, photonic crystal waveguides (PCWs) are specially used in compact devices, while photonic band-gap fibers (PBGFs) are usually used in short-distance propagation and high sensitive interferometers. In this paper, dispersion tailoring schemes for obtaining a high group index with the wide band and low group velocity dispersion (GVD) are reviewed in both PCWs and PBGFs. For the same purpose, we propose schemes for the slow-pulse propagation in PCWs based on the air-hole shifting method and in PBGFs based on the microfluid infiltration method, respectively. Simulation results using 2D plane wave expansion method and finite-difference timedomain (FDTD) method are given. Pulse distortion and design optimization are also discussed in some detail with the consideration of the practical fabrication errors. Slow-light pulse propagation in photonic crystal fiber is also demonstrated in the experiment based on stimulated Brillouin scattering.

  20. Fiber Optics

    NSDL National Science Digital Library

    Optical fibers transmit light signals and are widely used in the telecommunications industry to transmit data over long distances. Light travels through the core material of an optical fiber by essentially repeatedly bouncing off the cladding material that surrounds the core. Understanding refraction and how light behaves at the boundary of two different materials is the basis for understanding how fiber optic lines work. In particular, total internal reflection occurs when light travels in a material with a higher index of refraction toward a material with a lower index of refraction and the angle of incidence is greater than the critical angle.In this lesson, students investigate through experimentation, discussion, and video the phenomenon of total internal reflection and its relationship to fiber optics. Students also watch a video about dispersion and discuss the implications for fiber optics.Note: This is the second of two optics lesson plans. You may want to precede this lesson with The Index of Refraction Lesson Plan.

  1. Cutting with high-power Nd:YAG lasers and fiber for beam delivery

    NASA Astrophysics Data System (ADS)

    Haferkamp, Heinz; Homburg, Andreas

    1994-09-01

    Investigations have been carried out comparing thermal cutting using Nd:YAG and CO2 lasers. Analysis of the investigation results have led to conclusions concerning process efficiency, as referring to better absorption of laser radiation on metal-based materials at shorter wavelength behavior, as well as the influence of using an optical fiber for beam delivery on the processing results. The transmission properties of silica fibers with graded index and step index profile were investigated, when using a high power Nd:YAG laser. The beam parameters behind the two different fiber types related to the input parameters and the fiber geometry were theoretically and experimentally analyzed. The advantages and disadvantages for laser cutting with these fiber types are discussed with respect to physical properties and applicability.

  2. Photosensitivity and Hydroxyl in Hydrogenated Silica Fibers

    NASA Astrophysics Data System (ADS)

    Tan, Gu; Lin, Xiang-zhi; Liu, Hong-du; Fu, Li-bin; E, Pun Y. B.; P, Chung S.

    1998-09-01

    Optical loss spectra and refractive index changes have been measured in the hydrogenated standard telecommunication fiber and photosensitive fiber. The index changes due to ultraviolet exposure were found to be closely related with the OH formation in both types of fibers. A direct photolytical model is proposed to explain the effect of hydrogen loading on the enhancement of the photosensitivity in silica fibers.

  3. Index des mots-cls Keywords index

    E-print Network

    Boyer, Edmond

    Index des mots-clés Keywords index A Abies, 823 Abies alba, 265 acacia, 93 Acacia cyanophylla Lindl. grandis, 445 E. tereticornis, 445 early fire, 185 earlywood, 511 ecology, 823 ecophysiology, 823 grandis, 675 F Fagus sylvatica L., 761 fertility, 233 fiber, property, 491 fibre biometry, 283 finite

  4. High energy particle tracking using scintillating fibers and solid state photomultipliers

    SciTech Connect

    Petroff, M.D.; Atac, M.

    1989-01-01

    The Solid State Photomultiplier (SSPM) recently developed at the Rockwell International Science Center, coupled with fast scintillating fibers can have a rate capacity of 10/sup 8/ tracks per second per cm/sup 2/ of fiber cross section in systems for tracking of high energy ionizing particles. Relative to other approaches the SSPM can provide substantial improvements in spatial and temporal tracking accuracy. Results of preliminary experiments with 0.225 /times/ 0.225 mm/sup 2/ cross section step-index-of-refraction fiber exposed to electrons from a beta source are presented. The experiments involved pulse height analysis of SSPM photon detection pulses induced by coincident scintillations in two adjacent fibers traversed by the same electron. The data for two different scintillating fibers tested indicate that meter long fibers of this type, optimally coupled to SSPMs, will be effective in detecting minimum ionizing particles. 4 refs., 3 figs., 1 tab.

  5. 1052 IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. QE-18, NO. 7 , JULY 1982 Aer and a step-index multimode fiber, was investigated. As a

    E-print Network

    Rocca, Jorge J.

    and confine the electron beam. The elec- tron beam is produced by a glow discharge electron gun, and has) (b) Fig. 1. (d) Laser output power of the Zn 11 blue lines as a function of electron beam discharge. Uchida, "Self-sustained intensity oscillationof a laser diodeintroduced by a delayedelectrical feedback

  6. Few-mode fiber for optical MIMO transmission with low-computational complexity

    NASA Astrophysics Data System (ADS)

    Sakamoto, T.; Mori, T.; Yamamoto, T.; Yamamoto, F.

    2013-01-01

    This paper introduces our recent results on mode-division multiplexing transmission with MIMO processing. We have been studying coherent optical MIMO transmission systems and developing few-mode fibers to reduce the complexity of MIMO processing, for example, by using multi-step index fibers to control the differential mode delay (DMD) of the fibers and to compensate for the total DMD. We also investigated a transmission system using reduced-complexity MIMO processing. Finally, we review our latest 2×2 WDM-MIMO transmission experiments with low MIMO processing complexity.

  7. Two-step lateral taper spot-size converter for efficient fiber coupling to InP-based photonic integrated circuits

    Microsoft Academic Search

    Fang Wu; Valery I. Tolstikhin; Adam S. Densmore; Serge Grabtchak

    2004-01-01

    Spot-size converters (SSC) are an important building block of InP-based photonic integrated circuits since it allows a standard single-mode fiber with a large and symmetric mode spot to be efficiently coupled with large displacement tolerance to a semiconductor waveguide with a small and asymmetric mode spot. Having an on-chip SSC is practically advantageous since such an element greatly simplifies the

  8. Algorithm for estimation of material dispersion of fused silica glass optical fibers

    NASA Astrophysics Data System (ADS)

    Burdin, Vladimir A.

    2015-03-01

    The simple algorithm for taking into account the material dispersion in the calculations of the dispersion characteristics of optical fibers is introduced. In contrast to known solutions based on an approximation of dependencies of Sellmeier coefficients from the impurity concentration the proposed version of algorithm is based on the linear approximation of dependencies of the refractive index of the impurity concentration. The offered algorithm for calculating of the spectral characteristics of chromatic dispersion was tested on the examples of optical fibers with step-index profile. As examples it was considered the optical fiber with a pure silica glass as cladding material and a GeO2 doped silica glass as material of core and the optical fiber with fluorine doped silica glass as cladding material and pure silica glass as material of core. The comparison of the experimental data with the theoretical curves obtained using known methods and the theoretical curves obtained using proposed algorithms are presented.

  9. 4.7 Gbit\\/s transmission over 50m long 1mm diameter multi-core plastic optical fiber

    Microsoft Academic Search

    H. Yang; E. Tangdiongga; SCJ Lee; CM Okonkwo; Boom van den HPA; S. Randel; AMJ Koonen

    2010-01-01

    We report, for the first time, 4.7 Gbit\\/s transmission over 50 m long 1 mm diameter multi-core step-index plastic optical fiber, employing discrete multitone techniques and low-cost optical transceiver. A spectral efficiency of 13 bit\\/s\\/Hz is demonstrated.

  10. Study of lanthanum aluminum silicate glasses for passive and active optical fibers

    NASA Astrophysics Data System (ADS)

    Schuster, K.; Litzkendorf, D.; Grimm, S.; Kobelke, J.; Schwuchow, A.; Ludwig, A.; Leich, M.; Jetschke, S.; Dellith, J.; Auguste, J.-L.; Leparmentier, S.; Humbert, G.; Werner, G.

    2013-03-01

    We report on SiO2-Al2O3-La2O3 glasses - with and without Yb2O3 - suitable for nonlinear and fiber laser applications. We also present successful supercontinuum generation and fiber laser operation around 1060 nm in step-index fibers. We have optimized the glass compositions in terms of thermal and optical requirements for both a high La2O3 (24 mol%) and Yb2O3(6 mol%) concentration. The aluminum concentration was adjusted to about 21 mol% Al2O3 to increase the solubility of lanthanum and ytterbium in the glass beyond possible MCVD based techniques. The glasses have been characterized by dilatometrical methods to find transition temperatures from 860 to 880°C and thermal expansion coefficients between 4.1 and 7.0 × 10-6 K-1. Structured step index fibers with a SiO2-Al2O3-La2O3 core and silica cladding have been realized showing a fiber loss minimum of about 500 dB/km at 1200 nm wavelength. The chromatic dispersion could be adjusted to shift the zero dispersion wavelength (ZDW) close to the pump wavelength of 1550 nm in a supercontinuum generation setup. First fiber laser experiments show an efficiency of about 41 % with a remarkably reduced photodarkening compared to MCVD based fibers.

  11. An all-fiber vacuum sensor based on thermo-optics' effect in vanadium-doped fiber

    NASA Astrophysics Data System (ADS)

    Matjasec, Ziga; Donlagic, Denis

    2014-05-01

    This paper introduces an all-optical, fiber-optics vacuum sensor, which takes advantage of the thermo-optic effect within vanadium-co-doped fiber. This sensor utilizes a 980 nm pump-diode and a short section of highly absorbing vanadiumco- doped fiber produced by the flash vaporization process. The 980 nm source operates in pulse mode therefore the vanadium-co-doped fiber is periodically heated and self-cooled. The 980 nm pump-light is fully absorbed within the codoped fiber's core and relaxed as a heat, which changes the fiber's core refractive index. The heat-transfer between the heated fiber and surrounding gas depends on the gas pressure. Further, the doped-fiber is inserted into a Fabry-Perot interferometer which forms, in combination with a DFB laser diode at 1550 nm, a high coherence interferometer for optical path-length measurement. The time constant and absolute modulated optical path of the step response can be directly correlated with the gas pressure. The time constant is independent of the pump-diode's optical power, while the absolute modulated optical path also depends on the pump-diode's output of optical power and should thus be compensated. The vacuum sensor allows for a remote and fully dielectric measurement of the gas pressure and can be used in various industrial applications.

  12. Infrared photonic crystal fiber

    Microsoft Academic Search

    E. Rave; K. Roodenko; A. Katzir

    2003-01-01

    An infrared photonic crystal fiber has been made by multiple extrusions of silver halide (AgClxBr1-x) crystalline materials. The core of the fiber consisted of pure AgBr, and the cladding area included fiberoptic elements made of AgCl (with lower refractive index). Fibers of outer diameter 1 mm and length of the order of 1 m were flexible and transparent in the

  13. Drawing robust infrared optical fibers from preforms produced by efficient multimaterial stacked coextrusion

    NASA Astrophysics Data System (ADS)

    Tao, Guangming; Abouraddy, Ayman F.

    2014-03-01

    The utilization of infrared chalcogenide glass (ChG) fibers has long been hampered by the unfavorable mechanical characteristics typical of these glasses. Furthermore, the usual pathways to producing such fibers necessitate large-scale synthesis of high-purity glass, which represents a challenge in an academic environment, and thus presents an obstacle to the transfer of research results from academia to industry. Here we present our recent progress on multimaterial coextrusion technology that allows for high-efficiency disc-to-fiber manufacturing. A one-step extrusion from two glass discs (10-mm-diameter and 3-mm-thick) and a thermoplastic disc results in a robust step-index preform that is thermally drawn in an ambient atmosphere into continuous lengths of fiber with core diameters on the order of tens of micrometers. These results offer an alternative methodology that overcomes many of the traditional obstacles while potentially reducing the production cost.

  14. Efficient modeling of optical waveguides and fibers with chemical sensing applications

    NASA Astrophysics Data System (ADS)

    Weisshaar, Andreas; Remley, Kate A.

    1996-08-01

    The impedance boundary method of moments (IBMOM) for planar optical waveguides is reviewed. An extension of the IBMOM for optical fibers with truncated graded index profile is described. Results for a step index fiber show that virtually exact solutions for the modal field profile and propagation constant can be obtained with only three Legendre expansion functions. The IBMOM is applied in the design and analysis of an evanescent field optical waveguide chemical sensor which utilizes an antiresonant reflecting optical waveguide (ARROW) structure and is implemented as a Mach-Zehnder interferometer. The ARROW structure allows the use of a 5 micrometer wide guiding region for efficient coupling into a single mode optical fiber. The ARROW sensor is designed for a sensitivity of 180 degrees/cm phase change for a change of 0.05 in refractive index.

  15. High peak power amplification in large-core all-solid Yb fibers with an index-elevated pump clad and a low numerical aperture core

    NASA Astrophysics Data System (ADS)

    Leich, M.; He, W.; Grimm, S.; Kobelke, J.; Zhu, Y.; Müller, B.; Bierlich, J.; Bartelt, H.; Jäger, M.

    2015-03-01

    We report on the development of large-core Yb-doped fibers with up to 100 ?m core diameter and present first experimental results for high peak power amplification. The material for core and pump cladding was fabricated by Powder Sinter Technology. Using a high Al concentration we achieved a numerical aperture (NA) of 0.21 of the pump cladding and a core NA below 0.1. The rod-type fiber exhibits high pump absorption. Using a 0.55 m short fiber sample as the main amplifier in a 3-stage ns pulsed fiber Master Oscillator Power Amplifier system we achieved 3 ns output pulses with 360 kW peak power and 2 mJ pulse energy. We observed suppressed Stimulated Raman Scattering with respect to the signal pulses, which offers the possibility of further power scaling of such fiber amplifier systems.

  16. High-power monolithic fiber amplifiers based on advanced photonic crystal fiber designs

    NASA Astrophysics Data System (ADS)

    Sipes, Donald L.; Tafoya, Jason D.; Schulz, Daniel S.; Alkeskjold, Thomas Tanggaard; Weirich, Johannes; Olausson, Christina B.

    2014-03-01

    We report on the development and performance of a fully monolithic PCF amplifier that has achieved over 400 W with near diffraction limited beam quality with an approximately 1GHz phase modulated input. The key components for these amplifiers are an advanced PCF fiber design that combines segmented acoustically tailored (SAT) fiber that is gain tailored, a novel multi fiber-coupled laser diode stack and a monolithic 6+1x1 large fiber pump/signal multiplexer. The precisely aligned 2-D laser diode emitter array found in laser diode stacks is utilized by way of a simple in-line imaging process with no mirror reflections to process a 2-D array of 380-450 elements into 3 400/440?m 0.22NA pump delivery fibers. The fiber combiner is an etched air taper design that transforms low numerical aperture (NA), large diameter pump radiation into a high NA, small diameter format for pump injection into an air-clad large mode area PCF, while maintaining a constant core size through the taper for efficient signal coupling and throughput. The fiber combiner has 6 400/440/0.22 core/clad/NA pump delivery fibers and a 25/440 PM step-index signal delivery fiber on the input side and a 40/525 PM undoped PCF on the output side. The etched air taper transforms the six 400/440 ?m 0.22 NA pump fibers to the 525 ?m 0.55 NA core of the PCF fiber with a measured pump combining efficiency of over 95% with a low brightness drop. The combiner also operates as a stepwise mode converter via a 30 ?m intermediate core region in the combiner between the 20 ?m core of the input fiber and the 40 ?m fiber core of the PCF with a measured signal efficiency of 60% to 70% while maintaining polarization with a measured PER of 20 dB. These devices were integrated in to a monolithic fiber amplifier with high efficiency and near diffraction limited beam quality.

  17. Temperature and strain characterization of long period gratings in air guiding fiber

    NASA Astrophysics Data System (ADS)

    Iadicicco, Agostino; Cutolo, Antonello; Cusano, Andrea; Campopiano, Stefania

    2013-05-01

    This paper reports on the fabrication of Long Period Gratings (LPGs) in hollow-core air-silica photonic bandgap fibers by using pressure assisted Electrode Arc Discharge (EAD) technique. In particular, the fabrication procedure relies on the combined use of EAD step, to locally heat the HC fiber, and of a static pressure (slightly higher than the external one) inside the fiber holes, to modify the holes. This procedure permits to preserve the holey structure of the host fiber avoiding any hole collapsing and it enables a local effective refractive index change due to the size and shape modifications of core and cladding holes. Periodically repeated EAD treatments permit the fabrication of LPGs based devices in hollow core optical fibers enabling new functionalities hitherto not possible. Here, the experimental fabrication of LPG prototypes with different periods and lengths are discussed. And, the HC-LPGs sensitivity to environmental parameters such as strain and temperature are investigated.

  18. Fiber bundle phase conjugate mirror

    DOEpatents

    Ward, Benjamin G.

    2012-05-01

    An improved method and apparatus for passively conjugating the phases of a distorted wavefronts resulting from optical phase mismatch between elements of a fiber laser array are disclosed. A method for passively conjugating a distorted wavefront comprises the steps of: multiplexing a plurality of probe fibers and a bundle pump fiber in a fiber bundle array; passing the multiplexed output from the fiber bundle array through a collimating lens and into one portion of a non-linear medium; passing the output from a pump collection fiber through a focusing lens and into another portion of the non-linear medium so that the output from the pump collection fiber mixes with the multiplexed output from the fiber bundle; adjusting one or more degrees of freedom of one or more of the fiber bundle array, the collimating lens, the focusing lens, the non-linear medium, or the pump collection fiber to produce a standing wave in the non-linear medium.

  19. Robust multimaterial tellurium-based chalcogenide glass fibers for mid-wave and long-wave infrared transmission.

    PubMed

    Tao, Guangming; Shabahang, Soroush; Ren, He; Khalilzadeh-Rezaie, Farnood; Peale, Robert E; Yang, Zhiyong; Wang, Xunsi; Abouraddy, Ayman F

    2014-07-01

    We describe an approach for producing robust multimaterial chalcogenide glass fibers for mid-wave and long-wave mid-infrared transmission. By combining the traditional rod-in-tube process with multimaterial coextrusion, we prepare a hybrid glass-polymer preform that is drawn continuously into a robust step-index fiber with a built-in, thermally compatible polymer jacket. Using tellurium-based chalcogenides, the fibers have a transparency window covering the 3-12 ?m spectral range, making them particularly attractive for delivering quantum cascade laser light and in space applications. PMID:24978794

  20. Step Into Cyberspace

    NSDL National Science Digital Library

    2014-05-28

    In this activity, learners discover that they can modify a regular piece of paper so that it's large enough for them to walk through! Learners follow a cutting pattern on the printout, unfold it, and step through the paper. This activity may be extended with the challenge to recreate this cutting pattern on an index card.

  1. Picosecond Yb-doped single-trench fiber amplifier with diffraction limited output

    NASA Astrophysics Data System (ADS)

    Jain, Deepak; Gorman, Philip; Codemard, Christophe; Jung, Yongmin; Zervas, Michalis N.; Sahu, Jayanta K.

    2015-03-01

    We propose a novel fiber design single-trench fiber (STF) for large mode area fiber laser and amplifier. Fiber offers cylindrical symmetry and also offer higher refractive index of core compared to cladding. This avoids the need of stack and draw process and refractive index compensation of core doped with index raising rare earth and co-dopants ions, which are an indispensable condition in most of other fiber designs. That is why, this fiber design can be fabricated with conventional modified chemical vapour deposition process in conjunction with solution doping process, which can dramatically reduce the fabrication cost, hence suitable for mass production. Fiber offers very high loss (>10dB/m) and low power fraction in core (<50%) to the higher order modes for low loss of fundamental mode (<0.1dB/m) and high power fraction in core (>80%) thanks to the resonant coupling between core and ring modes. We fabricated a preform for 30?m core STF using MCVD process in conjunction with solution doping process in a single step, without using any micro-structuration and pixilation of core. Experiments ensure the robust single mode behaviour irrespective of launching condition of input beam. Furthermore, this fiber used in three stages MOPA provides 80kW peak pulses with repetition rate of 500 kHz, average power up to 10W, with M2 ~ 1.14. Moreover, all solid structure ensures easy cleaving and splicing. In nutshell, an ultra-low cost, monolithic, compact, and an effective single mode fiber amplifier device can be achieved using single-trench fiber.

  2. High index contrast platform for silicon photonics

    E-print Network

    Akiyama, Shoji, 1972-

    2004-01-01

    This thesis focuses on silicon-based high index contrast (HIC) photonics. In addition to mature fiber optics or low index contrast (LIC) platform, which is often referred to as Planar Lightwave Cirrcuit (PLC) or Silica ...

  3. Recent Results From the EU POF-PLUS Project: Multi-Gigabit Transmission Over 1 mm Core Diameter Plastic Optical Fibers

    Microsoft Academic Search

    C. M. Okonkwo; E. Tangdiongga; H. Yang; D. Visani; S. Loquai; R. Kruglov; B. Charbonnier; M. Ouzzif; I. Greiss; O. Ziemann; R. Gaudino; A. M. J. Koonen

    2011-01-01

    Recent activity to achieve multi-gigabit transmission over 1 mm core diameter graded-index and step-index plastic optical fibers for distances up to 50 meters is reported in this paper. By employing a simple intensity-modulated direct-detec- tion system with pulse amplitude or digital multi-tone modulation techniques, low-cost transceivers and easy to install large-core POFs, it is demonstrated that multi-gigabit transmission up to

  4. Comparison of nonlinear coefficient of optical fibers at 1550 nm

    Microsoft Academic Search

    V. L. Da Silva; Yanming Liu; A. J. Antos; G. E. Berkey; M. A. Newhouse

    1996-01-01

    Summary form only given. In this paper we report on measurements of the nonlinear coefficient (nonlinear refractive index\\/effective area) of different fibers of interest in transmission systems at 1550 nm: large-effective area fiber dispersion-shifted fiber (LEAF), dispersion-compensation fiber (DCF), and standard dispersion fibers.

  5. Large-aperture, tapered fiber-coupled, 10-kHz particle-image velocimetry.

    PubMed

    Hsu, Paul S; Roy, Sukesh; Jiang, Naibo; Gord, James R

    2013-02-11

    We demonstrate the design and implementation of a fiber-optic beam-delivery system using a large-aperture, tapered step-index fiber for high-speed particle-image velocimetry (PIV) in turbulent combustion flows. The tapered fiber in conjunction with a diffractive-optical-element (DOE) fiber-optic coupler significantly increases the damage threshold of the fiber, enabling fiber-optic beam delivery of sufficient nanosecond, 532-nm, laser pulse energy for high-speed PIV measurements. The fiber successfully transmits 1-kHz and 10-kHz laser pulses with energies of 5.3 mJ and 2 mJ, respectively, for more than 25 min without any indication of damage. It is experimentally demonstrated that the tapered fiber possesses the high coupling efficiency (~80%) and moderate beam quality for PIV. Additionally, the nearly uniform output-beam profile exiting the fiber is ideal for PIV applications. Comparative PIV measurements are made using a conventionally (bulk-optic) delivered light sheet, and a similar order of measurement accuracy is obtained with and without fiber coupling. Effective use of fiber-coupled, 10-kHz PIV is demonstrated for instantaneous 2D velocity-field measurements in turbulent reacting flows. Proof-of-concept measurements show significant promise for the performance of fiber-coupled, high-speed PIV using a tapered optical fiber in harsh laser-diagnostic environments such as those encountered in gas-turbine test beds and the cylinder of a combustion engine. PMID:23481818

  6. Ge-codoped laser fibers for mitigating Stimulated Brillouin Scattering in high power fiber amplifiers

    Microsoft Academic Search

    Xin Chen; Ming-Jun Li; Anping Liu

    2010-01-01

    Rare-earth doped fibers for high power fiber amplifiers normally have a small refractive index difference between the core and inner cladding, but have a larger core diameter than conventional telecom fibers. We take advantage of this feature as well as the difference between the optical and acoustic waveguides and proposed several fiber designs to mitigate Stimulated Brillouin Scattering (SBS) to

  7. Calculating a Biodiversity Index

    NSDL National Science Digital Library

    In this Biodiversity Counts activity, students learn how scientists calculate a biodiversity index using a page from the phone book as their data source. The printable five-page PDF handout includes a series of inquiry-based questions to get students thinking about what they already know about biodiversity and how living and non-living things are connected, step-by-step directions for calculating a biodiversity index, and a worksheet that includes brainstorming questions and areas for recording answers.

  8. Specially designed long period grating with internal geometric bending for enhanced refractive index sensitivity

    NASA Astrophysics Data System (ADS)

    Chiavaioli, F.; Trono, C.; Baldini, F.

    2013-06-01

    We propose a long period grating (LPG) characterized by specially designed refractive index (RI) profile in which each grating plane is tilted at increasing angles, as moving away from the center of symmetry of the structure towards its both edges. This internally manufactured geometric structure, which basically simulates the bending of an optical fiber, increases the RI sensitivity of an LPG to the external medium. We experimentally demonstrate a three-fold improvement in the RI sensitivity, thus providing the basis for another step forward in the field of RI sensors based on optical fiber gratings.

  9. Tapered GRIN fiber microsensor.

    PubMed

    Beltrán-Mejía, Felipe; Biazoli, Claudecir R; Cordeiro, Cristiano M B

    2014-12-15

    The sensitivity of an optical fiber microsensor based on inter-modal interference can be considerably improved by tapering a short extension of the multimode fiber. In the case of Graded Index fibers with a parabolic refractive index profile, a meridional ray exhibits a sinusoidal path. When these fibers are tapered, the period of the propagated beam decrease down-taper and increase up-taper. We take advantage of this modulation -along with the enhanced overlap between the evanescent field and the external medium- to substantially increase the sensitivity of these devices by tuning the sensor's maximum sensitivity wavelength. Moreover, the extension of this device is reduced by one order of magnitude, making it more propitious for reduced space applications. Numerical and experimental results demonstrate the success and feasibility of this approach. PMID:25606989

  10. The optimal fiber volume fraction and fiber-matrix property compatibility in fiber reinforced composites

    NASA Technical Reports Server (NTRS)

    Pan, Ning

    1992-01-01

    Although the question of minimum or critical fiber volume fraction beyond which a composite can then be strengthened due to addition of fibers has been dealt with by several investigators for both continuous and short fiber composites, a study of maximum or optimal fiber volume fraction at which the composite reaches its highest strength has not been reported yet. The present analysis has investigated this issue for short fiber case based on the well-known shear lag (the elastic stress transfer) theory as the first step. Using the relationships obtained, the minimum spacing between fibers is determined upon which the maximum fiber volume fraction can be calculated, depending on the fiber packing forms within the composites. The effects on the value of this maximum fiber volume fraction due to such factors as fiber and matrix properties, fiber aspect ratio and fiber packing forms are discussed. Furthermore, combined with the previous analysis on the minimum fiber volume fraction, this maximum fiber volume fraction can be used to examine the property compatibility of fiber and matrix in forming a composite. This is deemed to be useful for composite design. Finally some examples are provided to illustrate the results.

  11. Congenital fiber type disproportion myopathy caused by LMNA mutations.

    PubMed

    Kajino, Sachiko; Ishihara, Kayo; Goto, Kanako; Ishigaki, Keiko; Noguchi, Satoru; Nonaka, Ikuya; Osawa, Makiko; Nishino, Ichizo; Hayashi, Yukiko K

    2014-05-15

    A boy, who had shown muscle weakness and hypotonia from early childhood and fiber type disproportion (FTD) with no dystrophic changes on muscle biopsy, was initially diagnosed as having congenital fiber type disproportion (CFTD). Subsequently, he developed cardiac conduction blocks. We reconsidered the diagnosis as possible LMNA-myopathy and found a heterozygous mutation in the LMNA gene. This encouraged us to search for LMNA mutations on 80 patients who met the diagnostic criteria of CFTD with unknown cause. Two patients including the above index case had heterozygous in-frame deletion mutations of c.367_369delAAG and c.99_101delGGA in LMNA, respectively. Four of 23 muscular dystrophy patients with LMNA mutation also showed fiber type disproportion (FTD). Importantly, all FTD associated with LMNA-myopathy were caused by hypertrophy of type 2 fibers as compared with age-matched controls, whereas CFTD with mutations in ACTA1 or TPM3 showed selective type 1 fiber atrophy but no type 2 fiber hypertrophy. Although FTD is not a constant pathological feature of LMNA-myopathy, we should consider the possibility of LMNA-myopathy whenever a diagnosis of CFTD is made and take steps to prevent cardiac insufficiency. PMID:24642510

  12. Advanced components for multi-kW fiber lasers

    NASA Astrophysics Data System (ADS)

    Sipes, Donald L., Jr.; Tafoya, Jason D.; Schulz, Daniel S.; Ward, Benjamin G.; Carlson, Chad G.

    2012-02-01

    We report on the development and performance of a key components that enable the construction of multi-kW fiber amplifiers for government and industrial applications that are both reliable and highly affordable. The usefulness of these components span the range from single frequency near diffraction limited kW class fiber lasers to multimode wide linewidth fiber lasers for welding and cutting applications. The key components for these amplifiers are a novel multi fiber-coupled laser diode stack and a monolithic 6+1x1 large fiber pump/signal multiplexer. The precisely aligned 2-D laser diode emitter array found in laser diode stacks is utilized by way of a simple in-line imaging process with no mirror reflections to process a 2-D array of 380-450 elements into 3 400/440?m 0.22NA pump delivery fibers. The fiber combiner is an etched air taper design that transforms low numerical aperture (NA), large diameter pump radiation into a high NA, small diameter format for pump injection into an air-clad large mode area PCF, while maintaining a constant core size through the taper for efficient signal coupling and throughput. The fiber combiner has 6 400/440/0.22 core/clad/NA pump delivery fibers and a 20/440 PM step-index signal delivery fiber on the input side and a 40/525 PM undoped PCF on the output side. The etched air taper transforms the six 400/440 ?m 0.22 NA pump fibers to the 500 ?m 0.55 NA core of the PCF fiber with a measured pump combining efficiency of 92% with zero brightness drop. The combiner also operates as a stepwise mode converter via a 30 ?m intermediate core region in the combiner between the 20 ?m core of the input fiber and the 40 ?m fiber core of the PCF with a measured signal efficiency of 90% while maintaining polarization with a measured PER of 20 dB. We report the signal coupling efficiency and power handling capability as well.

  13. Scaling Fiber Lasers to Large Mode Area: An Investigation of Passive Mode-Locking Using a Multi-Mode Fiber

    PubMed Central

    Ding, Edwin; Lefrancois, Simon; Kutz, Jose Nathan; Wise, Frank W.

    2011-01-01

    The mode-locking of dissipative soliton fiber lasers using large mode area fiber supporting multiple transverse modes is studied experimentally and theoretically. The averaged mode-locking dynamics in a multi-mode fiber are studied using a distributed model. The co-propagation of multiple transverse modes is governed by a system of coupled Ginzburg–Landau equations. Simulations show that stable and robust mode-locked pulses can be produced. However, the mode-locking can be destabilized by excessive higher-order mode content. Experiments using large core step-index fiber, photonic crystal fiber, and chirally-coupled core fiber show that mode-locking can be significantly disturbed in the presence of higher-order modes, resulting in lower maximum single-pulse energies. In practice, spatial mode content must be carefully controlled to achieve full pulse energy scaling. This paper demonstrates that mode-locking performance is very sensitive to the presence of multiple waveguide modes when compared to systems such as amplifiers and continuous-wave lasers. PMID:21731106

  14. Scaling Fiber Lasers to Large Mode Area: An Investigation of Passive Mode-Locking Using a Multi-Mode Fiber.

    PubMed

    Ding, Edwin; Lefrancois, Simon; Kutz, Jose Nathan; Wise, Frank W

    2011-01-01

    The mode-locking of dissipative soliton fiber lasers using large mode area fiber supporting multiple transverse modes is studied experimentally and theoretically. The averaged mode-locking dynamics in a multi-mode fiber are studied using a distributed model. The co-propagation of multiple transverse modes is governed by a system of coupled Ginzburg-Landau equations. Simulations show that stable and robust mode-locked pulses can be produced. However, the mode-locking can be destabilized by excessive higher-order mode content. Experiments using large core step-index fiber, photonic crystal fiber, and chirally-coupled core fiber show that mode-locking can be significantly disturbed in the presence of higher-order modes, resulting in lower maximum single-pulse energies. In practice, spatial mode content must be carefully controlled to achieve full pulse energy scaling. This paper demonstrates that mode-locking performance is very sensitive to the presence of multiple waveguide modes when compared to systems such as amplifiers and continuous-wave lasers. PMID:21731106

  15. Dispersion tailoring in single mode optical fiber by doping silver nanoparticle

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Rik; Bhadra, Shyamal K.

    2013-05-01

    We propose an optical fiber which has very low dispersion loss (typically ~ 6.7 ps2/km at 1,550 nm) that can be achieved by doping Ag nanoparticle into the core glass. At low absorption loss approximation, dispersion free propagation can be achieved up to 64 km for a 20 ps pulse. Enhanced third order nonlinearity due to the presence of Ag nanoparticle (typically ~ 3.82 × 10-20 W/m2) compensates for long length dispersion broadening that is not possible in conventional fused silica step index fiber.

  16. Single mode fiber array for planet detection using a visible nulling interferometer

    NASA Technical Reports Server (NTRS)

    Liu, Duncan; Levine, B. Martin; Shao, Michael; Aguayo, Franciso

    2005-01-01

    We report the design, fabrication, and testing of a coherent large mode field diameter fiber array to be used as a spatial filter in a planet finding visible nulling interferometer. The array is a key component of a space instrument for visible-light detection and spectroscopy of Earth like extrasolar planets. In this concept, a nulling interferometer is synthesized from a pupil image of a single aperture which is then spatially filtered by a coherent array of single mode fibers to suppress the residual scattered star light. The use of the fiber array preserves spatial information between the star and planet. The fiber array uses a custom commercial large mode field or low NA step-index single mode fiber to relax alignment tolerances. A matching custom micro lens array is used to couple light into the fibers, and to recollimate the light out of the fiber array. The use of large mode field diameter fiber makes the fabrication of a large spatial filter array with 300 to 1000 elements feasible.

  17. Dispersion Compensating Fibers

    NASA Astrophysics Data System (ADS)

    Grüner-Nielsen, Lars; Knudsen, Stig Nissen; Edvold, Bent; Veng, Torben; Magnussen, Dorte; Larsen, C. Christian; Damsgaard, Hans

    2000-04-01

    The basic principles for use of dispersion compensating fibers (DCF) are reviewed, including definition of figure of merit and condition for dispersion slope compensation. The main design features of a triple-cladding index profile design are examined theoretically and experimentally. Production results are presented for three types of DCF. It is shown that polarization-mode dispersion can be reduced by introducing oscillatory twist into the fiber. The splice loss between DCF and standard fibers is shown to be reducible by use of a special intermediate fiber. Two methods for measuring the nonlinear effective area of DCF are compared and good agreement is found. Measurement results for the nonlinear refractive index n2 are reported. The nonlinear coefficient n2/ Aeff of DCF is found to be a factor of 5 higher than that on standard single-made fibers. The macrobending resistance of DCF is examined and found to be comparable with that of standard fibers. The microbending resistance of DCF is found to be better than that of standard fibers. Finally, positive results from a cabling experiment with DCF are reported.

  18. Study of in fiber Mach-Zehnder interferometer based on two spaced 3-dB long period gratings surrounded by a refractive index higher than that of silica

    NASA Astrophysics Data System (ADS)

    Duhem, O.; Henninot, J. F.; Douay, M.

    2000-06-01

    The paper deals with the response of a Mach-Zehnder interferometer composed by two 3-dB long period gratings (LPG) with different external refractive indices higher than that of silica (leaky configuration). A rough analysis of the cladding propagation arising in leaky configuration has allowed us to establish a model that is sufficient to describe the interferometer couplings evolution at the resonance. In particular, we have shown that the interferometer sensitivity depends strongly on its phase-shift ? ? and is optimized for ? ? equal to ? [2?] or 3?/4 [2?]. An experimental study was undertaken and allowed us to validate our model. Finally, a comparison with a single LPG demonstrated an increased sensitivity to the external index, suggesting the conception of a new fiber sensor operating with external refractive indices higher than that of silica.

  19. Genetics of Cotton Fiber Elongation

    E-print Network

    Ng, Eng Hwa

    2013-05-29

    ability GxE Genotype by environment interaction HVI High volume instrument Mic Micronaire (HVI) SCA Specific combining ability Str-H Fiber strength (HVI) Str-S Fiber strength (Stelometer) UHML Upper-half mean length (HVI) UI Uniformity index... OF TABLES ....................................................................................................... viii CHAPTER I INTRODUCTION .................................................................................. 1 CHAPTER II LITERATURE REVIEW...

  20. Effects of accelerated aging on fiber damage thresholds

    NASA Astrophysics Data System (ADS)

    Setchell, Robert E.

    1999-04-01

    Laser-induced damage mechanisms that can occur during high- intensity fiber transmission have been under study for a number of years. Our particular interest in laser initiation of explosives has led us to examine damage processes associated with the transmission of Q-switched, Nd:YAG pulses at 1.06 micrometers through step-index, multimode, fused silica fiber. Laser breakdown at the fiber entrance face is often the first process to limit fiber transmission, but catastrophic damage can also occur at either fiber end face, within the initial 'entry' segment of the fiber, and at other internal sites along the fiber path. Past studies have examined how these various damage mechanisms depend upon fiber end-face preparation, fiber fixturing and routing, laser characteristics, and laser-to-fiber injection optics. In some applications of interest, however, a fiber transmission system may spend years in storage before it is used. Consequently, an important additional issue for these applications is whether or not there are aging processes that can result in lower damage thresholds over time. Fiber end-face contamination would certainly lower breakdown and damage thresholds at these surfaces, but careful design of hermetic seals in connectors and other end-face fixtures can minimize this possibility. A more subtle possibility would be a process for the slow growth of internal defects that could lead to lower thresholds for internal damage. In the current study, two approaches to stimulating the growth of internal defects were used in an attempt to produce observable changes in internal damage threshold. In the first approach, test fibers were subjected to a very high tensile stress for a time sufficient for some fraction to fail from static fatigue. In the second approach, test fibers were subjected to a combination of high tensile stress and large, cyclic temperature variations. Both of these approaches were rather arbitrary due to the lack of an established growth mechanism for internal defects. Damage characteristics obtained from fibers subjected to each of these aging environments were compared to results from fresh fibers tested under identical conditions. A surprising result was that internal damage was not observed in any of the tested fibers. Only breakdown at the fiber entrance face and catastrophic damage at both end faces were observed. Fiber end faces were not sealed during the accelerated aging environments, and thresholds at these faces were significantly lower in the aged fibers. However, most fibers transmitted relatively high pulse energies before damaging, and a large fraction never damaged before we reached the limits of our test laser. The absence of any observable affect on internal damage thresholds is encouraging, but the current results do not rule out the possibility that some other approach to accelerated aging could reveal a growth mechanism for internal defects.

  1. Effects of Accelerated Aging on Fiber Damage Thresholds

    SciTech Connect

    Setchell, R.E.

    1999-02-15

    Laser-induced damage mechanisms that can occur during high-intensity fiber transmission have been under study for a number of years. Our particular interest in laser initiation of explosives has led us to examine damage processes associated with the transmission of Q-switched, Nd:YAG pulses at 1.06 {micro}m through step-index, multimode, fused silica fiber. Laser breakdown at the fiber entrance face is often the first process to limit fiber transmission but catastrophic damage can also occur at either fiber end face, within the initial entry segment of the fiber, and at other internal sites along the fiber path. Past studies have examined how these various damage mechanisms depend upon fiber end-face preparation, fiber fixturing and routing, laser characteristics, and laser-to-fiber injection optics. In some applications of interest, however, a fiber transmission system may spend years in storage before it is used. Consequently, an important additional issue for these applications is whether or not there are aging processes that can result in lower damage thresholds over time. Fiber end-face contamination would certainly lower breakdown and damage thresholds at these surfaces, but careful design of hermetic seals in connectors and other end-face fixtures can minimize this possibility. A more subtle possibility would be a process for the slow growth of internal defects that could lead to lower thresholds for internal damage. In the current study, two approaches to stimulating the growth of internal defects were used in an attempt to produce observable changes in internal damage thresholds. In the first approach test fibers were subjected to a very high tensile stress for a time sufficient for some fraction to fail from static fatigue. In the second approach, test fibers were subjected to a combination of high tensile stress and large, cyclic temperature variations. Both of these approaches were rather arbitrary due to the lack of an established growth mechanism for internal defects. Damage characteristics obtained from fibers subjected to each of these aging environments were compared to results from fresh fibers tested under identical conditions. A surprising result was that internal damage was not observed in any of the tested fibers. Only breakdown at the fiber entrance face and catastrophic damage at both end faces were observed. Fiber end faces were not sealed during the accelerated aging environments, and thresholds at these faces were significantly lower in the aged fibers. However, most fibers transmitted relatively high pulse energies before damaging, and a large fraction never damaged before we reached the limits of our test laser. The absence of any observable affect on internal damage thresholds is encouraging, but the current results do not rule out the possibility that some other approach to accelerated aging could reveal a growth mechanism for internal defects.

  2. Lignin-based Carbon Fibers: Effect of Synthetic Polymer Blending on Fiber Properties

    Microsoft Academic Search

    S. Kubo; J. F. Kadla

    2005-01-01

    Carbon fibers have been produced from hardwood lignin\\/synthetic polymer blend fibers. Hardwood kraft lignin was thermally blended with two recyclable polymers, poly(ethylene terephthalate) (PET) and polypropylene (PP). Both systems were easily spun into fibers. A thermostabilization step was utilized prior to carbonization to prevent fusion of individual fibers. For the lignin-based carbon fibers, careful control of heating rate was required.

  3. A New Type of Motor: Pneumatic Step Motor.

    PubMed

    Stoianovici, Dan; Patriciu, Alexandru; Petrisor, Doru; Mazilu, Dumitru; Kavoussi, Louis

    2007-02-01

    This paper presents a new type of pneumatic motor, a pneumatic step motor (PneuStep). Directional rotary motion of discrete displacement is achieved by sequentially pressurizing the three ports of the motor. Pulsed pressure waves are generated by a remote pneumatic distributor. The motor assembly includes a motor, gearhead, and incremental position encoder in a compact, central bore construction. A special electronic driver is used to control the new motor with electric stepper indexers and standard motion control cards. The motor accepts open-loop step operation as well as closed-loop control with position feedback from the enclosed sensor. A special control feature is implemented to adapt classic control algorithms to the new motor, and is experimentally validated. The speed performance of the motor degrades with the length of the pneumatic hoses between the distributor and motor. Experimental results are presented to reveal this behavior and set the expectation level. Nevertheless, the stepper achieves easily controllable precise motion unlike other pneumatic motors. The motor was designed to be compatible with magnetic resonance medical imaging equipment, for actuating an image-guided intervention robot, for medical applications. For this reason, the motors were entirely made of nonmagnetic and dielectric materials such as plastics, ceramics, and rubbers. Encoding was performed with fiber optics, so that the motors are electricity free, exclusively using pressure and light. PneuStep is readily applicable to other pneumatic or hydraulic precision-motion applications. PMID:21528106

  4. A New Type of Motor: Pneumatic Step Motor

    PubMed Central

    Stoianovici, Dan; Patriciu, Alexandru; Petrisor, Doru; Mazilu, Dumitru; Kavoussi, Louis

    2011-01-01

    This paper presents a new type of pneumatic motor, a pneumatic step motor (PneuStep). Directional rotary motion of discrete displacement is achieved by sequentially pressurizing the three ports of the motor. Pulsed pressure waves are generated by a remote pneumatic distributor. The motor assembly includes a motor, gearhead, and incremental position encoder in a compact, central bore construction. A special electronic driver is used to control the new motor with electric stepper indexers and standard motion control cards. The motor accepts open-loop step operation as well as closed-loop control with position feedback from the enclosed sensor. A special control feature is implemented to adapt classic control algorithms to the new motor, and is experimentally validated. The speed performance of the motor degrades with the length of the pneumatic hoses between the distributor and motor. Experimental results are presented to reveal this behavior and set the expectation level. Nevertheless, the stepper achieves easily controllable precise motion unlike other pneumatic motors. The motor was designed to be compatible with magnetic resonance medical imaging equipment, for actuating an image-guided intervention robot, for medical applications. For this reason, the motors were entirely made of nonmagnetic and dielectric materials such as plastics, ceramics, and rubbers. Encoding was performed with fiber optics, so that the motors are electricity free, exclusively using pressure and light. PneuStep is readily applicable to other pneumatic or hydraulic precision-motion applications. PMID:21528106

  5. Activated carbon fibers and engineered forms from renewable resources

    DOEpatents

    Baker, Frederick S

    2013-02-19

    A method of producing activated carbon fibers (ACFs) includes the steps of providing a natural carbonaceous precursor fiber material, blending the carbonaceous precursor material with a chemical activation agent to form chemical agent-impregnated precursor fibers, spinning the chemical agent-impregnated precursor material into fibers, and thermally treating the chemical agent-impregnated precursor fibers. The carbonaceous precursor material is both carbonized and activated to form ACFs in a single step. The method produces ACFs exclusive of a step to isolate an intermediate carbon fiber.

  6. Fiber coupled waveguide grating structures

    NASA Astrophysics Data System (ADS)

    Feng, Shengfei; Zhang, Xinping; Wang, Hao; Xin, Mudi; Lu, Zhenzhen

    2010-03-01

    Fabrication and characterization of the miniature device of waveguide grating-structures (WGS) on the end facet of an optical fiber are demonstrated. A layer of ZnO between the fiber and the grating structures serves as the waveguide. The fiber is used to direct the excitation light to the WGS and to carry the signal response back to the detection system. The narrow-band waveguide resonance mode tunable in the visible spectrum can be measured through the fiber in both the transmission and reflection. This nanodevice may be suitable as long-range sensors for the detection of refractive-index changes in nontransparent or toxic liquids.

  7. Vector Finite Element Modeling of the Full-Wave Maxwell Equations to Evaluate Power Loss in Bent Optical Fibers

    SciTech Connect

    Koning, J; Rieben, R; Rodrigue, G

    2004-12-09

    We measure the loss of power incurred by the bending of a single mode step-indexed optical fiber using vector finite element modeling of the full-wave Maxwell equations in the optical regime. We demonstrate fewer grid elements can be used to model light transmission in longer fiber lengths by using high-order basis functions in conjunction with a high order energy conserving time integration method. The power in the core is measured at several points to determine the percentage loss. We also demonstrate the effect of bending on the light polarization.

  8. A multicore optical fiber for distributed sensing

    NASA Astrophysics Data System (ADS)

    Sun, Xiaoguang; Li, Jie; Burgess, David T.; Hines, Mike; Zhu, Beyuan

    2014-06-01

    With advancements in optical fiber technology, the incorporation of multiple sensing functionalities within a single fiber structure opens the possibility to deploy dielectric, fully distributed, long-length optical sensors in an extremely small cross section. To illustrate the concept, we designed and manufactured a multicore optical fiber with three graded-index (GI) multimode (MM) cores and one single mode (SM) core. The fiber was coated with both a silicone primary layer and an ETFE buffer for high temperature applications. The fiber properties such as geometry, crosstalk and attenuation are described. A method for coupling the signal from the individual cores into separate optical fibers is also presented.

  9. Effect of pulses from a high-power ytterbium fiber laser on a material with a nonuniform refractive index. I. Irradiation of yttrium oxide targets

    NASA Astrophysics Data System (ADS)

    Osipov, V. V.; Lisenkov, V. V.; Platonov, V. V.; Orlov, A. N.; Podkin, A. V.; Savvin, I. A.

    2014-05-01

    The irradiation of Nd:Y2O3 targets with an absorption coefficient of 13-1.7 × 103 cm-1 using laser pulses with a duration of 0.1-3.5 ms and peak power of 200-700 W at a power density of (0.2-1.3) × 106 W/cm2 is studied. A relatively large spread of the delay times of laser plume, spike emission of the laser plume, cleavage of the front surface of the target, and greater ejection of substance from the crater in comparison with the effect of the CO2-laser radiation with almost the same power are demonstrated. A numerical model of the effect of radiation on a target with a nonuniform refractive index is proposed to interpret the destruction of dielectric material (cleavage of the front surface) and the large spread of the delay times of the plume.

  10. Optimal Strength Design for Fiber-Metal Laminates and Fiber-reinforced Plastic Laminates

    Microsoft Academic Search

    Wenjie Peng; Jianqiao Chen; Junhong Wei; Wenqiong Tu

    2011-01-01

    Optimal strength design of fiber-reinforced plastic (FRP) laminates and fiber-metal laminates (FML) is studied in this article. An optimization approach that integrates the particle swarm optimization algorithm and a general finite element code ANSYS was developed. ANSYS is utilized to obtain the failure index as fitness function and the optimum fitness is obtained by altering the fiber orientations. The strength

  11. Delivery of an ultrashort spatially focused pulse to the other end of a multimode fiber using digital phase conjugation

    NASA Astrophysics Data System (ADS)

    Morales Delgado, Edgar E.; Papadopoulos, Ioannis N.; Farahi, Salma; Psaltis, Demetri; Moser, Christophe

    2015-03-01

    Multimode optical fibers potentially allow the transmission of larger amounts of information than their single mode counterparts because of their high number of supported modes. However, propagation of a light pulse through a multimode fiber suffers from spatial distortions due to the superposition of the various exited modes and from time broadening due to modal dispersion. We present a method based on digital phase conjugation to selectively excite in a multimode fiber specific optical fiber modes that follow similar optical paths as they travel through the fiber. The excited modes interfere constructively at the fiber output generating an ultrashort spatially focused pulse. The excitation of a limited number of modes following similar optical paths limits modal dispersion, allowing the transmission of the ultrashort pulse. We have experimentally demonstrated the delivery of a focused spot of pulse width equal to 500 fs through a 30 cm, 200 micrometer core step-index multimode fiber. The results of this study show that two-photon imaging capability can be added to ultra-thin lensless endoscopy using commercial multimode fibers.

  12. A reliable, sensitive and fast optical fiber hydrogen sensor based on surface plasmon resonance.

    PubMed

    Perrotton, Cédric; Westerwaal, Ruud J; Javahiraly, Nicolas; Slaman, Martin; Schreuders, Herman; Dam, Bernard; Meyrueis, Patrick

    2013-01-14

    We report for the first time on the experimental response of a Surface Plasmon Resonance fiber optic sensor based on wavelength modulation for hydrogen sensing. This approach of measuring the hydrogen concentration makes the sensor insensitive to intensity fluctuations. The intrinsic fiber sensor developed provides remote sensing and enables the possibility of multi-points sensing. The sensor consists of a multilayer of 35 nm Au/180 nm SiO2/Pd deposited on a step- index multimode fiber core. The sensitivity and selectivity of the sensor are optimal at a Pd thickness of 3.75 nm. The sensor is sensitive to a hydrogen concentration ranging between 0.5 and 4% H2 in Ar, with a response time less than 15 s. PMID:23388931

  13. Fiber-optic sensors based on fluctuation oscillations of waveguide micro-optomechanical resonance structures

    NASA Astrophysics Data System (ADS)

    Egorov, F. A.

    2013-11-01

    The characteristics of fiber-optic oscillation frequency sensors of deformation and temperature that employ the thermal fluctuation resonant oscillations in the SMS(M) fiber structures (sensitive elements that represent oscillation systems with distributed parameters based on series-connected single- and multimode step-index fibers) are developed and studied. The measurements of the fluctuation oscillations are based on the amplitude-phase modulation of the optical wave in the multimode oscillating section due to variations in the path-length difference and tunneling of interfering beams. Accuracies of temperature and relative deformation measurements of ±2°C and ±10-5, respectively, are demonstrated. The estimation of the ultimate measurement sensitivity of the resonance frequency is based on the approximate calculation of the Allan variance that shows a possibility of the above sensors with temperature and deformation threshold sensitivities of 0.001°C and 10-8, respectively.

  14. Stepped nozzle

    DOEpatents

    Sutton, George P. (Danville, CA)

    1998-01-01

    An insert which allows a supersonic nozzle of a rocket propulsion system to operate at two or more different nozzle area ratios. This provides an improved vehicle flight performance or increased payload. The insert has significant advantages over existing devices for increasing nozzle area ratios. The insert is temporarily fastened by a simple retaining mechanism to the aft end of the diverging segment of the nozzle and provides for a multi-step variation of nozzle area ratio. When mounted in place, the insert provides the nozzle with a low nozzle area ratio. During flight, the retaining mechanism is released and the insert ejected thereby providing a high nozzle area ratio in the diverging nozzle segment.

  15. Stepped nozzle

    DOEpatents

    Sutton, G.P.

    1998-07-14

    An insert is described which allows a supersonic nozzle of a rocket propulsion system to operate at two or more different nozzle area ratios. This provides an improved vehicle flight performance or increased payload. The insert has significant advantages over existing devices for increasing nozzle area ratios. The insert is temporarily fastened by a simple retaining mechanism to the aft end of the diverging segment of the nozzle and provides for a multi-step variation of nozzle area ratio. When mounted in place, the insert provides the nozzle with a low nozzle area ratio. During flight, the retaining mechanism is released and the insert ejected thereby providing a high nozzle area ratio in the diverging nozzle segment. 5 figs.

  16. Tunable random fiber laser

    SciTech Connect

    Babin, S. A.; Podivilov, E. V. [Institute of Automation and Electrometry, SB RAS, Novosibirsk 630090 (Russian Federation); El-Taher, A. E.; Harper, P.; Turitsyn, S. K. [Photonics Research Group, Aston University, Birmingham, B4 7ET (United Kingdom)

    2011-08-15

    An optical fiber is treated as a natural one-dimensional random system where lasing is possible due to a combination of Rayleigh scattering by refractive index inhomogeneities and distributed amplification through the Raman effect. We present such a random fiber laser that is tunable over a broad wavelength range with uniquely flat output power and high efficiency, which outperforms traditional lasers of the same category. Outstanding characteristics defined by deep underlying physics and the simplicity of the scheme make the demonstrated laser a very attractive light source both for fundamental science and practical applications.

  17. Chiral fiber optical isolator

    NASA Astrophysics Data System (ADS)

    Kopp, Victor I.; Zhang, Guoyin; Zhang, Sheng; Genack, Azriel Z.; Neugroschl, Dan

    2009-02-01

    We propose an in-fiber chiral optical isolator based on chiral fiber polarizer technology and calculate its performance by incorporating the magnetic field into the scattering matrix. The design will be implemented in a special preform, which is passed through a miniature heat zone as it is drawn and twisted. The birefringence of the fiber is controlled by adjusted the diameter of a dual-core optical fiber. By adjusting the twist, the fiber can convert linear to circular polarization and reject one component of circular polarization. In the novel central portion of the isolator, the fiber diameter is large. The effective birefringence of the circular central core with high Verdet constant embedded in an outer core of slightly smaller index of refraction is small. The central potion is a non-reciprocal polarization converter which passes forward traveling left circularly polarized (LCP) light as LCP, while converting backward propagating LCP to right circularly polarized (RCP) light. Both polarizations of light traveling backwards are scattered out of the isolator. Since it is an all-glass structure, we anticipate that the isolator will be able to handle several watts of power and will be environmentally robust.

  18. Resonantly pumped amplification in a Tm-doped large mode-area photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Sincore, Alex; Shah, Lawrence; Wysmolek, Mateusz; Ryan, Robert; Abdulfattah, Ali; Richardson, Martin

    2015-03-01

    Ultra-large mode area thulium-doped photonic crystal fibers (Tm:PCF) have enabled the highest peak powers in 2 micron fiber laser systems to date. However, Tm:PCFs are limited by slope efficiencies of <50% when pumped with 790 nm laser diodes. A well-known alternative is pumping at 1550 nm with erbium/ytterbium-doped fiber (Er/Yb:fiber) lasers for efficiencies approaching ~70%. However, these 1550 nm pump lasers are also relatively inefficient themselves. A recently demonstrated and more attractive approach to enable slope efficiencies over 90% in thuliumdoped step-index fibers is resonant pumping (or in-band pumping). This utilizes a high power thulium fiber laser operating at a shorter wavelength as the pump. In this manuscript, we describe an initial demonstration of resonant pumping in Tm:PCF. While the extracted power was still in the exponential regime due to pump power limitations, slope efficiencies in excess of ~64 have been observed, and there is still room for improvement. These initial results show promise for applying resonant pumping in Tm:PCF to improve efficiencies and facilitate high power scaling in ultralarge mode area systems.

  19. Physiologically responsive, mechanically adaptive polymer optical fibers for optogenetics.

    PubMed

    Jorfi, Mehdi; Voirin, Guy; Foster, E Johan; Weder, Christoph

    2014-05-15

    The capability to deliver light to specific locations within the brain using optogenetic tools has opened up new possibilities in the field of neural interfacing. In this context, optical fibers are commonly inserted into the brain to activate or mute neurons using photosensitive proteins. While chronic optogenetic stimulation studies are just beginning to emerge, knowledge gathered in connection with electrophysiological implants suggests that the mechanical mismatch of conventional optical fibers and the cortical tissue may be a significant contributor to neuroinflammatory response. Here, we present the design and fabrication of physiologically responsive, mechanically adaptive optical fibers made of poly(vinyl alcohol) (PVA) that may mitigate this problem. Produced by a one-step wet-spinning process, the fibers display a tensile storage modulus E' of ?7000??MPa in the dry state at 25°C and can thus readily be inserted into cortical tissue. Exposure to water causes a drastic reduction of E' to ?35??MPa on account of modest swelling with the water. The optical properties at 470 and 590 were comparable with losses of 0.7±0.04??dB/cm at 470 nm and 0.6±0.1??dB/cm at 590 nm in the dry state and 1.1±0.1??dB/cm at 470 nm and 0.9±0.3??dB/cm at 590 nm in the wet state. The dry end of a partially switched fiber with a length of 10 cm was coupled with a light-emitting diode with an output of 10.1 mW to deliver light with a power density of >500??mW/cm2 from the wet end, which is more than sufficient to stimulate neurons in vivo. Thus, even without a low-refractive index cladding, the physiologically responsive, mechanically adaptive optical fibers presented here appear to be a very useful new tool for future optogenetic studies. PMID:24978225

  20. FLAX FIBERS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Flax (Linum usitatissimum L.) is a versatile plant, supplying both fiber and seed for industrial uses. The long, strong fibers processed for linen are prized for comfort and appearance in textiles, while shorter fibers are used in textile blends and for specialty paper, reinforced composites, and a...

  1. Heterostructured photonic crystal fiber

    Microsoft Academic Search

    M. Yan; P. Shum; X. Yu

    2005-01-01

    We introduce heterostructured photonic crystal fibers whose cladding and core are two lattice-matched photonic crystals (PCs). Confined modes, particularly those due to photonic bandgaps (PBGs) possessed by cladding PC, can be quickly predicted by studying cladding PBG regions and space-filling modes of the core PC. We theoretically demonstrate that PBG-guided modes can be either index-guided or antiguided locally in the

  2. Carbon Fibers Conductivity Studies

    NASA Technical Reports Server (NTRS)

    Yang, C. Y.; Butkus, A. M.

    1980-01-01

    In an attempt to understand the process of electrical conduction in polyacrylonitrile (PAN)-based carbon fibers, calculations were carried out on cluster models of the fiber consisting of carbon, nitrogen, and hydrogen atoms using the modified intermediate neglect of differential overlap (MINDO) molecular orbital (MO) method. The models were developed based on the assumption that PAN carbon fibers obtained with heat treatment temperatures (HTT) below 1000 C retain nitrogen in a graphite-like lattice. For clusters modeling an edge nitrogen site, analysis of the occupied MO's indicated an electron distribution similar to that of graphite. A similar analysis for the somewhat less stable interior nitrogen site revealed a partially localized II electron distribution around the nitrogen atom. The differences in bonding trends and structural stability between edge and interior nitrogen clusters led to a two-step process proposed for nitrogen evolution with increasing HTT.

  3. Microstructured fibers for sensing applications

    NASA Astrophysics Data System (ADS)

    Petrovich, M. N.; van Brakel, A.; Poletti, F.; Mukasa, K.; Austin, E.; Finazzi, V.; Petropoulos, P.; O'Driscoll, E.; Watson, M.; DelMonte, T.; Monro, T. M.; Dakin, J. P.; Richardson, D. J.

    2005-11-01

    Microstructured fibers (MOFs) are among the most innovative developments in optical fiber technology in recent years. These fibers contain arrays of tiny air holes that run along their length and define the waveguiding properties. Optical confinement and guidance in MOFs can be obtained either through modified total internal reflection, or photonic bandgap effects; correspondingly, they are classified into index-guiding Holey Fibers (HFs) and Photonic Bandgap Fibers (PBGFs). MOFs offer great flexibility in terms of fiber design and, by virtue of the large refractive index contrast between glass/air and the possibility to make wavelength-scale features, offer a range of unique properties. In this paper we review the current status of air/silica MOF design and fabrication and discuss the attractions of this technology within the field of sensors, including prospects for further development. We focus on two primary areas, which we believe to be of particular significance. Firstly, we discuss the use of fibers offering large evanescent fields, or, alternatively, guidance in an air core, to provide long interaction lengths for detection of trace chemicals in gas or liquid samples; an improved fibre design is presented and prospects for practical implementation in sensor systems are also analysed. Secondly, we discuss the application of photonic bandgap fibre technology for obtaining fibres operating beyond silica's transparency window, and in particular in the 3?m wavelength region.

  4. Ultrasensitive fiber optic sensors and their applications

    Microsoft Academic Search

    SungHyun Nam; Jon Lee; Shizhuo Yin; Karl Reichard; Paul Ruffin; Qing Wang

    2005-01-01

    In this paper, a brief review on ultrasensitive fiber optic sensors and their applications, done recently at Penn State, is presented. Our discussions will mainly focus on two types of highly sensitive fiber optic sensors. One type is based on the combination of single resonant band long period gratings (LPGs) with the second refractive index matched polymer cladding layer. The

  5. Fiber optic level sensor for cryogens

    NASA Technical Reports Server (NTRS)

    Sharma, M.

    1981-01-01

    Sensor is useful in cryogenic environments where liquids of very low index of refraction are encountered. It is "yes/no" indication of whether liquid is in contact with sensor. Sharp bends in fiber alter distribution of light among propagation modes. This amplifies change in light output observed when sensor contacts liquid, without requiring long fiber that would increse insertion loss.

  6. Hollow fiber liquid phase microextraction as a preconcentration and clean-up step after pressurized hot water extraction for the determination of non-steroidal anti-inflammatory drugs in sewage sludge

    Microsoft Academic Search

    Abolfazl Saleh; Estelle Larsson; Yadollah Yamini; Jan Åke Jönsson

    2011-01-01

    A method for the quantitative determination of non-steroidal anti-inflammatory drugs (NSAIDs) in sewage sludge was developed and validated. The target compounds were extracted using pressurized hot water extraction (PHWE) and then purified and preconcentrated by three-phase hollow fiber liquid phase microextraction (HF-LPME) followed by LC–ESI-MS analysis. The PHWE was optimized with regard to the pH of solvent as well as

  7. High-Temperature Resistance Fiber Bragg Grating Temperature Sensor Fabrication

    Microsoft Academic Search

    Bowei Zhang; Mojtaba Kahrizi

    2007-01-01

    Fiber Bragg grating (FBG) temperature sensor and sensor arrays were applied widespread particularly in harsh environments. Although FBGs are often referring to permanent refractive index modulation in the fiber core, exposure to high-temperature environments usually results in the bleach of the refractive index modulation. The maximum temperature reported for the conventional FBG temperature sensor is around 600 degC due to

  8. Distributed fiber optical HC leakage and pH sensing techniques for implementation into smart structures

    NASA Astrophysics Data System (ADS)

    Buerck, Jochen M.; Vogel, Bernhard H.; Roth, Siegmar; Ebrahimi, Sasan; Kraemer, Karl

    2004-07-01

    Interaction of target molecules with the evanescent wave of light guided in optical fibers is among the most promising sensing schemes for building up smart chemical sensor technologies. If the technique of optical time domain reflectometry (OTDR) is combined with silicone-clad quartz glass fibers distributed chemical sensing is possible. Hydrocarbon (HC) detection and location is done by automated identification of the position of the corresponding step drop (light loss) in the backscatter signal induced by local refractive index increase in the silicone cladding due to a penetrating HC compound. A commercially available mini-OTDR was adapted to sensing fibers of up to nearly 2-kilometer length and location of typical HC fuels could be demonstrated. The instrument is applicable for fuel leakage monitoring in large technical installations such as tanks or pipelines with spatial resolution down to 1 m. A similar technique using measurements in the Vis spectral range is being developed for health monitoring of large structures, e.g., for early detection of corrosion caused by water ingress and pH changes in reinforced concrete. Here, a pH indicator dye and a phase transfer reagent are immobilized in the originally hydrophobic fiber cladding, leading to a pH induced absorption increase and a step drop signal in the backscatter curve. The configuration of the distributed sensing cables, the instrumental setups, and examples for HC and pH sensing are presented.

  9. Analysis of the backscattering method for testing optical fiber cables

    Microsoft Academic Search

    E.-G. Neumann

    1980-01-01

    The backscattering method for measuring the attenuation of optical glass fiber waveguides and the insertion loss of fiber connections is analysed for a fiber of arbitrary refractive index profile taking into account the different attenuation for the transmitted and the backscattered light as well as the anisotropy of the Rayleigh scattering. The results of the analysis are applied to discuss

  10. Transmission measurements of hollow-core THz Bragg fibers

    E-print Network

    Skorobogatiy, Maksim

    Transmission measurements of hollow-core THz Bragg fibers Alexandre Dupuis,* Karen Stoeffler, Bora 135293); published March 23, 2011 We report on the terahertz (THz) spectral characteristics of hollow-core THz Bragg fibers. Two types of high-index contrast Bragg fibers were fabricated: one based

  11. Adaptive Receiver Structures for Fiber Communication Systems Employing Polarization

    E-print Network

    Gesbert, David

    components from their mixtures at the end of the fiber channel. This is in fact the focus of this article the algorithmic com- plexity in a fairly low level that is suitable for implementation in optical fiber. Index Terms-- Blind Signal Processing, PMD, PDM, Fiber Optic. I. INTRODUCTION CEntral to the research

  12. Hollow multilayer photonic bandgap fibers for NIR applications

    E-print Network

    Bayindir, Mehmet

    -gap fibers," Science 301, 1702-1704 (2003). 8. F. Benadid, J. C. Knight, G. Antonopoulos, P. St. J. Russell, "Stimulated raman scattering in hydrogen-filled hollow-core photonic crystal fiber," Science 298, 399, "Photonic crystal fibers: effective-index and bandgap guidance," in Photonic Crystals and Light Localization

  13. "Photonic lantern" spectral filters in multi-core Fiber.

    PubMed

    Birks, T A; Mangan, B J; Díez, A; Cruz, J L; Murphy, D F

    2012-06-18

    Fiber Bragg gratings are written across all 120 single-mode cores of a multi-core optical Fiber. The Fiber is interfaced to multimode ports by tapering it within a depressed-index glass jacket. The result is a compact multimode "photonic lantern" filter with astrophotonic applications. The tapered structure is also an effective mode scrambler. PMID:22714465

  14. Supercontinuum Generation in Optical Fibers

    NASA Astrophysics Data System (ADS)

    Dudley, J. M.; Taylor, J. R.

    2010-04-01

    1. Introduction and history J. R. Taylor; 2. Supercontinuum generation in microstructure fiber - an historical note J. K. Ranka; 3. Nonlinear fiber optics overview J. C. Travers, M. H. Frosz and J. M. Dudley; 4. Fiber supercontinuum generation overview J. M. Dudley; 5. Silica fibers for supercontinuum generation J. C. Knight and W. Wadsworth; 6. Supercontinuum generation and nonlinearity in soft glass fibers J. H. V. Price and D. J. Richardson; 7. Increasing the blue-shift of a picosecond pumped supercontinuum M. H. Frosz, P. M. Moselund, P. D. Rasmussen, C. L. Thomsen and O. Bang; 8. Continuous wave supercontinuum generation J. C. Travers; 9. Theory of supercontinuum and interactions of solitons with dispersive waves D. V. Skryabin and A. V. Gorbach; 10. Interaction of four-wave mixing and stimulated Raman scattering in optical fibers S. Coen, S. G. Murdoch and F. Vanholsbeeck; 11. Nonlinear optics in emerging waveguides: revised fundamentals and implications S. V. Afshar, M. Turner and T. M. Monro; 12. Supercontinuum generation in dispersion varying fibers G. Genty; 13. Supercontinuum generation in chalcogenide glass waveguides Dong-Il Yeom, M. R. E. Lamont, B. Luther Davies and B. J. Eggleton; 14. Supercontinuum generation for carrier-envelope phase stabilization of mode-locked lasers S. T. Cundiff; 15. Biophotonics applications of supercontinuum generation C. Dunsby and P. M. W. French; 16. Fiber sources of tailored supercontinuum in nonlinear microspectroscopy and imaging A. M. Zheltikov; Index.

  15. Low cost fiber optic sensing of sugar solution

    NASA Astrophysics Data System (ADS)

    Muthuraju, M. E.; Patlolla, Anurag Reddy; Vadakkapattu Canthadai, Badrinath; Pachava, Vengalrao

    2015-03-01

    The demand for highly sensitive and reliable sensors to assess the refractive index of liquid get many applications in chemical and biomedical areas. Indeed, the physical parameters such as concentration, pressure and density, etc., can be found using the refractive index of liquid. In contrast to the conventional refractometer for measurement, optical fiber sensor has several advantages like remote sensing, small in size, low cost, immune to EMI etc., In this paper we have discussed determination of refractive index of sugar solution using optical fiber. An intensity modulated low cost plastic fiber optic refractive index sensor has been designed for the study. The sensor is based on principle of change in angle of reflected light caused by refractive index change of the medium surrounding the fiber. The experimental results obtained for the sugar solution of different refractive indices prove that the fiber optic sensor is cable of measuring the refractive indices as well as the concentrations.

  16. Chemical composition fiber gratings in a high mixed gamma neutron radiation field

    Microsoft Academic Search

    A. Fernandez Fernandez; B. Brichard; F. Berghmans; H. El Rabii; M. Fokine; M. Popov

    2006-01-01

    Fiber Bragg gratings are all-fiber wavelength-selective refractive index structures manufactured through UV exposure of optical fibers. Their applications range from WDM all-fiber filters, dispersion compensators and fiber laser resonators for optical telecommunication applications to different types of point or distributed optical fiber sensors for a large variety of applications. The nuclear industry is considering the use of photonic technology for

  17. Two kinds of novel tunable Thulium-doped fiber laser

    NASA Astrophysics Data System (ADS)

    Ma, Xiaowei; Chen, Daru; Feng, Gaofeng; Yang, Junyong

    2014-11-01

    Two kinds of tunable Thulium-doped fiber laser (TDFL) respectively using a Sagnac loop mirror and a novel tunable multimode interference (MMI) fiber filter are experimentally demonstrated. The TDFL with the Sagnac loop mirror made by a 145.5-cm polarization-maintaining fiber (PMF) can operate with stable dual-wavelength lasing or tunable single-wavelength lasing around 1860nm. Both stable dual-wavelength and tunable single-wavelength lasing are achieved by adjusting a polarization controller in the Sagnac loop mirror. The TDFL with a novel tunable MMI fiber filter formed by splicing a segment of a special no-core fiber that is an all silica fiber without fiber core to single mode fibers can achieve tuning range from 1813.52 nm to 1858.70 nm. The no-core fiber with a large diameter of 200 ?m is gradually vertically covered by refractive index matching liquid, which leads to a wavelength tuning of the transmission peak of the MMI fiber filter. The relationship between the refractive index of the refractive index matching liquid and the peak wavelength shift of the MMI fiber filter is also discussed. Using the MMI fiber filter, a Thulium-doped fiber laser with a tuning range of 45.18 nm is demonstrated.

  18. Dietary Fiber and Weight Gain

    Microsoft Academic Search

    Robert J. L. Waugh

    2010-01-01

    To the Editor: The study by Dr Ludwig and colleagues 1 pro- vides evidence that a high intake of low-fiber foods is a key me- diator of the epidemic of obesity in the United States. The au- thors plausibly suggest that this effect is primarily attributable to the often high glycemic index of such foods. A secondary but no less

  19. Tunable photonic band gap fiber

    Microsoft Academic Search

    R. T. Bise; R. S. Windeler; K. S. Kranz; C. Kerbage; B. J. Eggleton; D. J. Trevor

    2002-01-01

    The ability to change the photonic band gap structure continuously and reversibly by modifying the index thermally allows the band gap features to be sensitively tuned, allowing for a thorough investigation of the various band gap guiding properties. Furthermore, it may be possible to use this type of band gap fiber as a tunable filter. Investigations of the dispersion properties

  20. Single-mode fiber optic in electronic speckle pattern interferometry

    Microsoft Academic Search

    Wei Liu; Yushan Tan; Xianglin Wang; Haitao Wang; Lijun Jiang

    1993-01-01

    A new technique has been developed for applying fiber optics to electronic speckle pattern interferometry (ESPI) to measure unbonded faults in the carbon\\/epoxy honeycomb composite. The fiberized ESPI system we designed is introduced in detail. This paper also develops the theoretical and experimental approach of singlemode fiber optics phase-step ESPI. This approach produces a significant improvement in fringe contrast and

  1. Multiplexed displacement fiber sensor using thin core fiber exciter

    NASA Astrophysics Data System (ADS)

    Chen, Zhen; Hefferman, Gerald; Wei, Tao

    2015-06-01

    This letter reports a multiplexed optical displacement sensor using a thin core fiber (TCF) exciter. The TCF exciter is followed by a stripped single mode optical fiber. A small section of buffer is used as the movable component along the single mode fiber. Ultra-weak cladding mode reflection (< - 75 dB) was employed to probe the refractive index discontinuity between the air and buffer coating boundary. The position change of the movable buffer segment results in a delay change of the cladding mode reflection. Thus, it is a measure of the displacement of the buffer segment with respect to the glass fiber. The insertion loss of one sensor was measured to be less than 3 dB. A linear relationship was evaluated between the measurement position and absolute position of the moving actuator. Multiplexed capability was demonstrated and no cross talk was found between the sensors.

  2. Thermal degradation of short polyester fiber-polyurethane elastomer composite

    Microsoft Academic Search

    F. Suhara; S. K. N. Kutty; G. B. Nando

    1998-01-01

    The thermal degradation of short polyester fiber reinforced polyurethane composites with and without different bonding agents has been studied by thermogravimetric analysis. It was found that degradation of the polyurethane takes place in two steps and that of the composites takes place in three steps. With the incorporation of 30 phr of fiber in the matrix, the onset of degradation

  3. High-Bandwidth Plastic Optical Fiber for Fiber to the Display

    Microsoft Academic Search

    Yasuhiro Koike; Takaaki Ishigure

    2006-01-01

    Novel photonics polymer devices for broadband technologies are described, focusing on the high-bandwidth graded-index plastic optical fiber (GI POF). Based on these photonics polymer device technologies, the concept of \\

  4. Unique dispersion properties of photonic crystal fibers

    Microsoft Academic Search

    Knnimasa Saitoh; Masanori Koshiba

    2003-01-01

    In conventional photonic crystal fibers (PCFs), the cladding structure is usually formed by air holes with the same diameter arrayed in a regular triangular lattice. However, in index-guiding PCFs, the periodicity in the cladding region is not essential to confine the guiding light into the high-index core region. In this paper, we report that it is possible to control chromatic

  5. Characterizing germania concentration and structure in fiber soot using multiphoton microscopy and spectroscopy technology

    NASA Astrophysics Data System (ADS)

    Chen, Minghan; Li, Ming-Jun; Liu, Anping

    2015-02-01

    Germania doping is commonly used in the core of optical fiber due to its advantages compared to other materials such as superior transparency in near-infrared telecommunication wavelength region. During fiber preform manufacturing using the outside vapor deposition (OVD) process, Ge is doped into a silica soot preform by chemical vapor deposition. Since the Ge doping concentration profile is directly correlated with the fiber refractive index profile, its characterization is critical for the fiber industry. Electron probe micro-analyzer (EPMA) is a conventional analysis method for characterizing the Ge concentration profile. However, it requires extensive sample preparation and lengthy measurement. In this paper, a multiphoton microscopy technique is utilized to measure the Ge doping profile based on the multiphoton fluorescence intensity of the soot layers. Two samples, one with ramped and another with stepped Ge doping profiles were prepared for measurements. Measured results show that the technique is capable of distinguishing ramped and stepped Ge doping profiles with good accuracy. In the ramped soot sample, a sharp increment of doping level was observed in about 2 mm range from soot edge followed by a relative slow gradient doping accretion. As for the stepped doping sample, step sizes ranging from around 1 mm (at soot edge) to 3 mm (at soot center) were observed. All the measured profiles are in close agreement with that of the EPMA measurements. In addition, both multiphoton fluorescence (around 420 nm) and sharp second harmonic generations (at 532 nm) were observed, which indicates the co-existence of crystal and amorphous GeO2.

  6. On the possible use of optical fiber Bragg gratings as strain sensors for geodynamical monitoring

    Microsoft Academic Search

    Pietro Ferraro; Giuseppe De Natale

    2002-01-01

    Optical fiber sensors can be used to measure many different parameters including strain, temperature, pressure, displacement, electrical field, refractive index, rotation, position and vibrations. Among a variety of fiber sensors, fiber Bragg gratings (FBG) have numerous advantages over other optical fiber sensors. One of the major advantages of this type of sensors is attributed to wavelength-encoded information given by the

  7. DIETARY FIBER

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This chapter explores the role of dietary fiber in human diets, health, and medicine. Dietary fiber contributes to human health by maintenance of normal gastrointestinal tract function. The polysaccharides and lignin present in cell walls of plant-derived foods are the primary source of dietary fibe...

  8. Banana fiber-reinforced biodegradable soy protein composites

    Microsoft Academic Search

    Rakesh Kumar; Veena Choudhary; Saroj Mishra; Ik Varma

    2008-01-01

    Banana fiber, a waste product of banana cultivation, has been used to prepare banana fiber reinforced soy protein composites.\\u000a Alkali modified banana fibers were characterized in terms of density, denier and crystallinity index. Fourier transformed\\u000a infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) were also performed\\u000a on the fibers. Soy protein composites were prepared by incorporating different

  9. Interferometric Fiber Optic Sensors

    PubMed Central

    Lee, Byeong Ha; Kim, Young Ho; Park, Kwan Seob; Eom, Joo Beom; Kim, Myoung Jin; Rho, Byung Sup; Choi, Hae Young

    2012-01-01

    Fiber optic interferometers to sense various physical parameters including temperature, strain, pressure, and refractive index have been widely investigated. They can be categorized into four types: Fabry-Perot, Mach-Zehnder, Michelson, and Sagnac. In this paper, each type of interferometric sensor is reviewed in terms of operating principles, fabrication methods, and application fields. Some specific examples of recently reported interferometeric sensor technologies are presented in detail to show their large potential in practical applications. Some of the simple to fabricate but exceedingly effective Fabry-Perot interferometers, implemented in both extrinsic and intrinsic structures, are discussed. Also, a wide variety of Mach-Zehnder and Michelson interferometric sensors based on photonic crystal fibers are introduced along with their remarkable sensing performances. Finally, the simultaneous multi-parameter sensing capability of a pair of long period fiber grating (LPG) is presented in two types of structures; one is the Mach-Zehnder interferometer formed in a double cladding fiber and the other is the highly sensitive Sagnac interferometer cascaded with an LPG pair. PMID:22736961

  10. All-fiber Passively Q-switched Laser Based on Tm3+-doped Tellurite Fiber

    E-print Network

    Kuan, Pei-Wen; Li, Kefeng; Zhang, Lei; Fan, Xiaokang; Hasan, Tawfique; Wang, Fengqiu; Hu, Lili

    2014-12-24

    developments of saturable absorber (SA) materials, passively Q-switched pulse lasers have been realized by utilizing CNTs [7] , graphene [8], SESAMs [9], Cr2+:ZnSe crystals [10], metal dichalcogenides [11], rare-earth doped fibers [12], etc. By virtue... [15, 16]. A high repetition rate mode-locking operation was also achieved in the silicate fiber [17]. Nevertheless, hardly any passive Q-switched lasers using multi-component glass fibers have been demonstrated. High refractive index, high rare...

  11. Integrated fiber optic backscatter system for photon correlation spectroscopy

    NASA Astrophysics Data System (ADS)

    Dhadwal, Harbans S.; Khan, Romel R.; Suh, Kwang

    1995-04-01

    Design and fabrication of an integrated backscatter fiber optic probe is described in this paper. A short section of a gradient index optical fiber is fusion spliced to two separate monomode optical fibers; the two fibers are mounted into a stainless steel face plate. One fiber is used to transmit either a focussed or collimated laser beam to the scattering region. The second fiber collects and guides the laser light scattered at a predefined scattering angle to a photomultiplier. Subsequent photon correlation and analysis yields size information of the scattering species.

  12. A novel dispersion compensating fiber with multiple windows based on hybrid photonic crystal fiber

    Microsoft Academic Search

    Ying Liu; Yuquan Li; Rong Wang; Jingyuan Wang; Yang Su; Xiaogang Xie

    2011-01-01

    A novel dispersion compensating fiber with multiple windows is firstly proposed. The proposed DCF is based on hybrid photonic crystal fiber. This type of DCF gets a multiple negative dispersion windows by the coupling between the hybrid guiding mode in the edge of each band-gap and the index guiding mode in the cladding deficit area. This is very different from

  13. Estimation of ovular fiber production in cotton

    DOEpatents

    Van`t Hof, J.

    1998-09-01

    The present invention is a method for rendering cotton fiber cells that are post-anthesis and pre-harvest available for analysis of their physical properties. The method includes the steps of hydrolyzing cotton fiber cells and separating cotton fiber cells from cotton ovules thereby rendering the cells available for analysis. The analysis of the fiber cells is through any suitable means, e.g., visual inspection. Visual inspection of the cells can be accomplished by placing the cells under an instrument for detection, such as microscope or other means. 4 figs.

  14. Optimization and Application of Reflective LSPR Optical Fiber Biosensors Based on Silver Nanoparticles.

    PubMed

    Chen, Jiangping; Shi, Se; Su, Rongxin; Qi, Wei; Huang, Renliang; Wang, Mengfan; Wang, Libing; He, Zhimin

    2015-01-01

    In this study, we developed a reflective localized surface plasmon resonance (LSPR) optical fiber sensor, based on silver nanoparticles (Ag NPs). To enhance the sensitivity of the LSPR optical sensor, two key parameters were optimized, the length of the sensing area and the coating time of the Ag NPs. A sensing length of 1.5 cm and a 1-h coating time proved to be suitable conditions to produce highly sensitive sensors for biosensing. The optimized sensor has a high refractive index sensitivity of 387 nm/RIU, which is much higher than that of other reported individual silver nanoparticles in solutions. Moreover, the sensor was further modified with antigen to act as a biosensor. Distinctive wavelength shifts were found after each surface modification step. In addition, the reflective LSPR optical fiber sensor has high reproducibility and stability. PMID:26016910

  15. Simulation of the coherent MDM transmission using principal modes of the optical fiber as signal carriers

    NASA Astrophysics Data System (ADS)

    Lyubopytov, Vladimir S.; Zakirov, Robert A.; Vinogradova, Irina L.; Sultanov, Albert K.

    2015-03-01

    In this paper we demonstrate computer simulation results obtained for the coherent mode division multiplexed (MDM) 5x5 QPSK transmission using principal modes (PMs) of the stepped-index few-mode fiber (FMF) as a basis of independent signal carriers. The output signal recovering and the fiber propagation matrix determination are considered to be carried out in optical domain by means of reconfigurable multibranch diffractive optical elements (DOEs). Both the cases of Gaussian and Nyquist raised-cosine pulse shaping are considered for optical signal modulation. The simulation results show, that the transmission in the basis of PMs in strong coupling regime allows the reliability of the coherent MDM system to be fundamentally improved. As a result, utilization of the optical signal processing for MDM transmission could minimize substantially the DSP circuit complexity required for the real-time recovering of the transmitted signal.

  16. Self-Organized Coherence In Fiber Laser Arrays

    Microsoft Academic Search

    M. L. Minden; Hans Bruesselbach; J. L. Rogers; G. J. Dunning; D. L. Hammon; A. J. Solis; L. Vaughan

    Self-organized coherence between fiber lasers has been reported both via all-fiber 2x2 directional coupler trees and in spatially multi-core fibers. We have taken this a major step forward, coupling together a number of independent fiber lasers to obtain a spatially and spectrally coherent far field, with no active length, polarization, or amplitude control. The near field output comes from a

  17. Ultra-short pulsed fiber ring laser using photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Ma, Shaozhen; Li, Wenbo; Hu, Hongyu; Dutta, Niloy K.

    2012-06-01

    A fiber ring laser which generates ~ 570 ps wide pulse train at 40 GHz has been demonstrated using a photonic crystal fiber as a nonlinear optical loop mirror (NOLM). Theoretical simulation of the NOLM transmission has been carried out using the split-step Fourier method.

  18. In-Line Fiber Optic Interferometric Sensors in Single-Mode Fibers

    PubMed Central

    Zhu, Tao; Wu, Di; Liu, Min; Duan, De-Wen

    2012-01-01

    In-line fiber optic interferometers have attracted intensive attention for their potential sensing applications in refractive index, temperature, pressure and strain measurement, etc. Typical in-line fiber-optic interferometers are of two types: Fabry-Perot interferometers and core-cladding-mode interferometers. It's known that the in-line fiber optic interferometers based on single-mode fibers can exhibit compact structures, easy fabrication and low cost. In this paper, we review two kinds of typical in-line fiber optic interferometers formed in single-mode fibers fabricated with different post-processing techniques. Also, some recently reported specific technologies for fabricating such fiber optic interferometers are presented. PMID:23112608

  19. Immigration Index

    NSDL National Science Digital Library

    Striving to become the "immigration resource directory on the net," the Immigration Index is a newly launched Website dedicated to news and information about immigration worldwide. Along with breaking headlines from a variety of news sources about immigration-related issues such as asylum, migration, trafficking and women, and much more, the site contains a fully annotated collection of links to immigration materials all around the World Wide Web. Only a month old, some of the categories in the Index's hierarchy still need some filling in. In time, however, the Immigration Index promises to become an invaluable resource for interested parties.

  20. 2 step/multi step equations

    NSDL National Science Digital Library

    Mr. Elmer

    2010-10-27

    There is practice modeling 2 step and multi-step equations with manipulatives. There is also a couple of videos demonstrating 2 step equations. There is a great resource at Illuminations.nctm.org 2 step equation model There are questions, instructions, and extensions to the lesson. Either show the given worksheet (PDF) or pass it out. Read the opening paragraph and discuss the situation. Ask why Mr. Roberts wouldn't want to open the crates. Follow the directions, showing the inverse operations on ...

  1. Overview Of Fiber Optic Research At Brown University

    NASA Astrophysics Data System (ADS)

    Morse, Ted F.

    1990-02-01

    Research in the Laboratory for Lightwave Technology is focused on novel applications of specially designed optical fibers. Emphasis is placed on new techniques of dopant incorporation, using both MCVD (Modified Chemical Vapor Deposition) and OVD (Outside Vapor Deposition) to fabricate fibers that are primarily for non-telecommunications applications. The topics pursued are fibers for fiber lasers, nonlinear effects in fibers, in particular, second harmonic generation, fiber devices for the measurement of electric field, new techniques for the fabrication of bulk-glass gradient index lenses, fiber designs for embedded fibers for sensor elements of future "smart skin" composites, the poling of glasses to induce anisotropy or possibly optical activity, and finally, fiber designs for N x N fused taper couplers.

  2. Interference phenomena in fraunhofer holograms and in their reconstructions of tapered glass fibers.

    PubMed

    Lomas, G M

    1969-10-01

    Fraunhofer holograms and their reconstructions show interference fringes when applied to tapered glass fibers, which do not occur with opaque fibers. The fringes are shown to be quantitatively related to fiber profile. The phase lag of fiber transmitted light is recorded as identifiable hologram fringes by interference with fiber-diffracted light. This also results in fringes in the reconstructed image. One fringe of both types, for a fiber refractive index n, represents a diameter change lambda/(n-1). Shape changes along a fiber not directly resolved by the optics are measurable. Profile measurement of attenuating glass fibers in the continuous filament process is described. PMID:20072569

  3. Modal noise impact in radio over fiber multimode fiber links.

    PubMed

    Gasulla, I; Capmany, J

    2008-01-01

    A novel analysis is given on the statistics of modal noise for a graded-index multimode fiber (MMF) link excited by an analog intensity modulated laser diode. We present the speckle contrast as a function of the power spectrum of the modulated source and the transfer function of the MMF which behaves as an imperfect transversal microwave photonic filter. The theoretical results confirm that the modal noise is directly connected with the coherence properties of the optical source and show that the performance of high-frequency Radio Over Fiber (ROF) transmission through MMF links for short and middle reach distances is not substantially degraded by modal noise. PMID:18521139

  4. Concentric core optical fiber with multiple-mode signal transmission

    DOEpatents

    Muhs, Jeffrey D. (Lenoir City, TN)

    1997-01-01

    A concentric core optical fiber provides for the simultaneous but independent transmission of signals over a single optical fiber. The concentric optical fiber is constructed of a single-mode or multimode inner optical fiber defined by a core and a cladding of a lower index of refraction than the core and an outer optical fiber defined by additional cladding concentrically disposed around the cladding and of an index of refraction lower than the first mentioned cladding whereby the latter functions as the core of the outer optical fiber. By employing such an optical fiber construction with a single-mode inner core or optical fiber, highly sensitive interferometric and stable less sensitive amplitude based sensors can be placed along the same length of a concentric core optical fiber. Also, by employing the concentric core optical fiber secure telecommunications can be achieved via the inner optical fiber since an intrusion of the concentric optical fiber will first cause a variation in the light being transmitted through the outer optical fiber and this variation of light being used to trigger a suitable alarm indicative of the intrusion.

  5. Concentric core optical fiber with multiple-mode signal transmission

    DOEpatents

    Muhs, J.D.

    1997-05-06

    A concentric core optical fiber provides for the simultaneous but independent transmission of signals over a single optical fiber. The concentric optical fiber is constructed of a single-mode or multimode inner optical fiber defined by a core and a cladding of a lower index of refraction than the core and an outer optical fiber defined by additional cladding concentrically disposed around the cladding and of an index of refraction lower than the first mentioned cladding whereby the latter functions as the core of the outer optical fiber. By employing such an optical fiber construction with a single-mode inner core or optical fiber, highly sensitive interferometric and stable less sensitive amplitude based sensors can be placed along the same length of a concentric core optical fiber. Also, by employing the concentric core optical fiber secure telecommunications can be achieved via the inner optical fiber since an intrusion of the concentric optical fiber will first cause a variation in the light being transmitted through the outer optical fiber and this variation of light being used to trigger a suitable alarm indicative of the intrusion. 3 figs.

  6. Multi-kW single fiber laser based on an extra large mode area fiber design

    NASA Astrophysics Data System (ADS)

    Langner, Andreas; Such, Mario; Schötz, Gerhard; Just, Florian; Leich, Martin; Schwuchow, Anka; Grimm, Stephan; Zimer, Hagen; Kozak, Marcin; Wedel, Björn; Rehmann, Georg; Bachert, Charley; Krause, Volker

    2012-02-01

    The quality of Yb-doped fused bulk silica produced by sintering of Yb-doped fused silica granulates has improved greatly in the past five years [1 - 4]. In particular, the refractive index and doping level homogeneity of such materials are excellent and we achieved excellent background fiber attenuation of the active core material down to about 20 dB/km at 1200 nm. The improvement of the Yb-doped fused bulk silica has enabled the development of multi-kW fiber laser systems based on a single extra large multimode laser fiber (XLMA fiber). When a single active fiber is used in combination with the XLMA multimode fiber of 1200 ?m diameter simple and robust high power fiber laser setups without complex fiber coupling and fiber combiner systems become possible. In this papper, we will discuss in detail the development of the core material based on Yb-doped bulk silica and the characterization of Yb-doped fibers with different core compositions. We will also report on the excellent performance of a 4 kW fiber laser based on a single XLMA-fiber and show the first experimental welding results of steel sheets achieved with such a laser.

  7. All-fiber and fiber compatible acousto-optic modulators with potential biomedical applications

    NASA Astrophysics Data System (ADS)

    Abdulhalim, I.; Gannot, Israel; Pannell, C. N.

    2006-02-01

    All-fiber acousto-optic (AO) devices such as frequency shifters, phase, intensity and polarization modulators, tunable filters and multiplexers have been developed in the last decade mostly for their importance in fiber optic communication systems. However they can equally have potential uses in bio sensing and fiber based biomedical systems. We present the design, construction and performance of a number of all-fiber and fiber compatible acousto-optic modulators that particularly phase and polarization modulators and will address their potential uses in biomedicine. Among these components and devices, an all-fibre phase modulator acts on the phase of optical fields that propagate down the fibre core. To enhance the phase modulation, the acoustic energy is focused into the fiber core using an acoustic lens. Another high efficiency birefringence (or polarization) modulator was demonstrated that is designed to operate at the acoustic resonance frequency of the fiber. Fiber compatible devices were built using gradient index (GRIN) lenses that can couple the light into a fiber or between two fibers. Diffraction based and polarization GRIN modulators were demonstrated and AOMs of in-fiber gratings as well as ones made from glasses that exhibit large AO figure of merit. As a high frequency polarization, phase, intensity or wavelength modulators these devices have a great potential for use in polarimetric imaging, scanning of a fiber-optic OCT system, tuning the wavelengths in miniature hyperspectral imaging systems and sensors or for frequency-domain OCT.

  8. Rapid Quantification of 3D Collagen Fiber Alignment and Fiber Intersection Correlations with High Sensitivity

    PubMed Central

    Sun, Meng; Bloom, Alexander B.; Zaman, Muhammad H.

    2015-01-01

    Metastatic cancers aggressively reorganize collagen in their microenvironment. For example, radially orientated collagen fibers have been observed surrounding tumor cell clusters in vivo. The degree of fiber alignment, as a consequence of this remodeling, has often been difficult to quantify. In this paper, we present an easy to implement algorithm for accurate detection of collagen fiber orientation in a rapid pixel-wise manner. This algorithm quantifies the alignment of both computer generated and actual collagen fiber networks of varying degrees of alignment within 5°°. We also present an alternative easy method to calculate the alignment index directly from the standard deviation of fiber orientation. Using this quantitative method for determining collagen alignment, we demonstrate that the number of collagen fiber intersections has a negative correlation with the degree of fiber alignment. This decrease in intersections of aligned fibers could explain why cells move more rapidly along aligned fibers than unaligned fibers, as previously reported. Overall, our paper provides an easier, more quantitative and quicker way to quantify fiber orientation and alignment, and presents a platform in studying effects of matrix and cellular properties on fiber alignment in complex 3D environments. PMID:26158674

  9. Analysis of mode transitions in a long-period fiber grating with a nano-overlay of diamond-like carbon

    NASA Astrophysics Data System (ADS)

    Brabant, D.; Koba, M.; Smietana, Mateusz; Bock, Wojtek J.

    2014-09-01

    This work presents optimization analysis of the sensitivity to variations of the external refractive index (RI) of long-period fiber grating (LPFG) coated with a nano-overlay of diamond-like carbon (DLC) material. Through numerical simulations, we have shown that both the dual-resonance and mode transition phenomena can be simultaneously exploited to substantially increase the sensitivity to variations of the external RI. The tuning of the DLC layer thickness to displace the dual-resonance band into a more suitable region of the spectrum is also reported. To perform this analysis, we implemented a novel pseudo-heuristic simulation model based on a 4-layer step-index fiber layer model and coupled mode theory. The dispersion dependence on the DLC overlay thickness was modeled from experimental data. LPFG parameters were fitted to an experimental transmission spectrum. The simulation model and the obtain results provides guidance for the fabrication of the device.

  10. Pragmatic Approach to Subject Indexing: A New Concept.

    ERIC Educational Resources Information Center

    Dutta, S.; Sinha, P. K.

    1984-01-01

    Describes adoption at Sorghum and Millets Information Center (India) of Pragmatic Approach to Subject Index (PASI), computer-manipulative indexing procedure in which key words are arranged in meaningful sequence. Indexing problems, search for suitable system, PASI indexing steps, and computerization are discussed. Thirteen references and…

  11. Stepping motor controller

    DOEpatents

    Bourret, Steven C. (Los Alamos, NM); Swansen, James E. (Los Alamos, NM)

    1984-01-01

    A stepping motor is microprocessingly controlled by digital circuitry which monitors the output of a shaft encoder adjustably secured to the stepping motor and generates a subsequent stepping pulse only after the preceding step has occurred and a fixed delay has expired. The fixed delay is variable on a real-time basis to provide for smooth and controlled deceleration.

  12. Fireblocking Fibers

    NASA Technical Reports Server (NTRS)

    1986-01-01

    PBI was originally developed for space suits. In 1980, the need for an alternative to asbestos and stricter government anti-pollution standards led to commercialization of the fire blocking fiber. PBI is used for auto racing driver suits and aircraft seat covers. The fiber does not burn in air, is durable and easily maintained. It has been specified by a number of airliners and is manufactured by Hoechst-Celanese Corporation.

  13. UK Index

    NSDL National Science Digital Library

    The UK Index provides a searchable index of resources in or about the United Kingdom. The Quick Reference section offers links to News Resources in the UK such as the BBC, weather information, UK record charts, and UK related USENET newsgroups. The Foreign & Commonwealth Office provides good advice for travelers. The search engine allows the selection of categories such as arts or business to restrict the search to pages included in one category or a combination of categories.

  14. Experimental investigations of an all-fiber multireflector spectral filter for optical communications 

    E-print Network

    Lee, Jong-Seo

    2004-09-30

    . Then four polishing steps with increasingly finer grit were applied to produce high-quality polished end surfaces on each fiber section. Finally, a dielectric mirror was deposited on one end of each fiber section by magnetron sputtering. After...

  15. Inverse Variation: Step By Step Lesson

    NSDL National Science Digital Library

    2012-01-01

    This step by step lesson from the Math Ops website explains inverse variation. Students can read the text or follow along as it is read out loud. The lesson includes nine slides which explain what an inverse variation equation is, and include several real world examples of this type of mathematical model.

  16. A novel optical fiber biochemical sensor based on long period grating

    NASA Astrophysics Data System (ADS)

    Mao, Xianhui; Liao, Yanbiao; Zhang, Min; Lai, Shurong; Yin, Haibo

    2007-09-01

    In this paper, our present work, which aimed at investigating a novel optical fiber biochemical sensor based on long period grating (LPG), is introduced. Biochemical sensor is one of the most attractive fields of sensor research, especially with the development and occurrence of all kinds of novel theory and technology such as LPG. When there is a refraction index periodic perturbation, the guiding mode and cladding mode in LPG couple with each other. This make the LPG is sensitive to the ambient refractive index. This means it can be a novel bio-chemical sensor when it is applied in the fields of biochemistry. After investigating the principle of coupling in LPG, where the formulas of resonance wave length and band width are induced by 3-layer step index model, we developed an optical fiber biochemical sensor. The structure of its probe is designed by coating some function films whose thickness is between several tens and several hundreds nanometers on the cladding of optical fiber. Experiments of monitoring the saline separateness process of Bovine Serum Albumin (BSA) and Mice-Immunoglobulin G (M-IgG) by using the developed LPG sensor have been done. The monitoring indicated that for the BSA, the saline separateness occurs when the saturation is between 50% and 60%, for the M-IgG, the percentage is between 30%-40%. Besides the monitoring, the experiments could also analyze the effects of protein type (different molecule structure), protein consistency and saline saturation to saline separateness. The experimental results show that the optical fiber biochemical sensor based on LPG has many advantages such as simple structure, high sensitivity and miniature. It has a promising future in many research fields and application fields.

  17. OTDR characterization of the minimum reflection signature from PMMA fiber splices

    NASA Astrophysics Data System (ADS)

    Lawson, Christopher M.; Michael, Robert R., Jr.; Salazar, Roberto A.; Harmony, David W.; Finn, Gregory M.

    1993-02-01

    Optical time domain reflectometry (OTDR) measurements have been performed to characterize the minimum reflection signature from PMMA plastic fiber splices. The dominant splice reflection sources due to inexact index matching and fiber core misalignment were carefully examined. A clearly detectable intrinsic OTDR reflection signature was observed with all tested fibers. The measured reflectivities varied from -54 to -27 dB. The characteristics of this signature were mapped out vs. experimental variables such as fiber surface roughness, polishing procedure, fiber-fiber alignment, and index matching characteristics.

  18. Longitudinal strain sensing with photonic crystal fibers and fiber Bragg gratings

    NASA Astrophysics Data System (ADS)

    Tenderenda, T.; Murawski, M.; Szymanski, M.; Szostkiewicz, L.; Becker, M.; Rothhardt, M.; Bartelt, H.; Mergo, P.; Poturaj, Kl; Makara, M.; Skorupski, K.; Marc, P.; Jaroszewicz, L. R.; Nasilowski, T.

    2014-03-01

    Photonic crystal fibers (PCF), sometimes also referred to as microstructured fibers (MSF), have been a subject of extensive research for over a decade. This is mainly due to the fact that by changing the geometry and distribution of the air holes the fiber properties can be significantly modified and tailored to specific applications. In this paper we present the results of a numerical analysis of the influence of the air-hole distribution on the sensitivity of the propagated modes' effective refractive index to externally applied longitudinal strain. We propose an optimal strain sensitive fiber design, with a number of fibers drawn and experimentally evaluated to confirm the theoretical results. Furthermore as the direct measurement of the effective refractive index change may be complex and challenging in field environment, we propose to use fiber Bragg gratings (FBG) in our sensing set-up. As the Bragg wavelength is a function of the effective refractive index, the external strain changes can be monitored through the Bragg wavelength shift with a simple optical spectrometer. Moreover, since the PCF is also optimized for low-loss splicing with standard single mode fiber, our novel sensor head can be used with standard off-the-shelf components in complex multiplexed sensing arrays, with the measured signal transmitted to and from the sensor head by standard telecom fibers, which significantly reduces costs.

  19. 2568 JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 23, NO. 8, AUGUST 2005 Long-Period Fiber Grating Fabrication by

    E-print Network

    Nikogosyan, David N.

    . The thermal studies of the recorded gratings were also conducted. Index Terms--Laser excitation, optical fiber laser (244 nm) [4]. Such UV laser irradiation leads to a refractive-index change in the Ge- doped fiber2568 JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 23, NO. 8, AUGUST 2005 Long-Period Fiber Grating

  20. New optical W-fiber Panda for fiber optic gyroscope sensitive coil

    Microsoft Academic Search

    A. M. Kurbatov; R. A. Kurbatov

    2010-01-01

    Based on refractive index W-profile, two kinds of single-mode fibers are proposed: polarizing (bend type) and linear polarization\\u000a maintaining (PM-fiber) with low losses (up to 0.35 dB\\/km). The polarizing W-fiber allows one to combine the dichroism in wide\\u000a spectral range with opportunity to have almost any desirable mode field diameter (MFD). The PM-fiber low losses are essentially\\u000a determined by fundamental

  1. Fluoride glass fibers: applications and prospects

    NASA Astrophysics Data System (ADS)

    Poulain, Marcel

    1998-09-01

    Fluoride glass fibers have been intensively developed for the last 20 years. A major effort was devoted to the fabrication of low loss fibers for repeaterless long haul telecommunications. This step which ended in the late eighties provided the basic technology for the manufacturing of multimode and single mode fibers with minimum losses below 10 dB/km. Such fibers area now used for various passive applications requiring the handling of IR signal. In this respect, fluoride fibers are complementary to silica fibers when wavelength exceeds 2 micrometers . Some practical set ups are operating for IR imaging, remote spectroscopy and thermometry. Special fibers such as polarization maintaining fibers have been developed for interferometric astronomy, which could also apply to sensors. UV transmission has still to be developed. Laser power delivery is another field of application for these fibers. YAG:Er laser at 2.9 micrometers attracts a growing interest for medical applications, ophthalmology and dentistry, while prospects for CO laser are positive. Active fibers are based on rare earth doped single mode fibers. They lead to the definition of numerous new laser lines and emphasized the potential of up conversion for the generation of visible light using IR pumping laser diodes. High power output has been achieved in the blue and the red light, which open prospects for compact and all solid state fiber lasers for a wide range of applications, from displays to medical uses. Optical amplification makes another field of R and D centered on telecommunication needs. Pr3+ doped fluoride fibers have been used for the 1.3 micrometers band, and Er based fluoride fiber amplifiers exhibit wider and flatter gain than those made from silica. Optical amplification may be implemented at other wavelengths for more general purposes.

  2. Artificially disordered birefringent optical fibers.

    PubMed

    Herath, S; Puente, N P; Chaikina, E I; Yamilov, A

    2012-02-13

    We develop and experimentally verify a theory of evolution of polarization in artificially-disordered multi-mode optical fibers. Starting with a microscopic model of photo-induced index change, we obtain the first and second order statistics of the dielectric tensor in a Ge-doped fiber, where a volume disorder is intentionally inscribed via UV radiation transmitted through a diffuser. A hybrid coupled-power & coupled-mode theory is developed to describe the transient process of de-polarization of light launched into such a fiber. After certain characteristic distance, the power is predicted to be equally distributed over all co-propagating modes of the fiber regardless of their polarization. Polarization-resolved experiments, confirm the predicted evolution of the state of polarization. Complete mode mixing in a segment of fiber as short as ? 10cm after 3.6dB insertion loss is experimentally observed. Equal excitation of all modes in such a multi-mode fiber creates the conditions to maximize the information capacity of the system under e.g. multiple-input-multiple-output (MIMO) transmission setup. PMID:22418121

  3. Mode-dependent characteristics of Rayleigh backscattering in weakly-coupled few-mode fiber

    NASA Astrophysics Data System (ADS)

    Yu, Dawei; Fu, Songnian; Tang, Ming; Liu, Deming

    2015-07-01

    We theoretically investigate the mode-dependent characteristics of Rayleigh backscattering arising in weakly-coupled few-mode fibers (FMFs). Based on the theory of Lorentz reciprocity and surface wave excitation, we derive a general analytical equation of excitation efficiency and power distribution of Rayleigh backscattering light among backward propagation modes under the condition of impulse response. Thus, we are able to characterize the Rayleigh backscattering of weakly-coupled FMF with arbitrary refractive index profile. As for the weakly-coupled FMF with a step-index profile, the power distribution ratio of individual modes in the Rayleigh backscattering light is mainly determined by the forward propagation mode. In particular, the backscattering mode with the same profile as the forward propagation one has the highest excitation efficiency. The FMF parameters have influence on the total backscattering power, but little effect on the mode power distribution ratio.

  4. Fibrillogenesis in continuously spun synthetic collagen fiber.

    PubMed

    Caves, Jeffrey M; Kumar, Vivek A; Wen, Jing; Cui, Wanxing; Martinez, Adam; Apkarian, Robert; Coats, Julie E; Berland, Keith; Chaikof, Elliot L

    2010-04-01

    The universal structural role of collagen fiber networks has motivated the development of collagen gels, films, coatings, injectables, and other formulations. However, reported synthetic collagen fiber fabrication schemes have either culminated in short, discontinuous fiber segments at unsuitably low production rates, or have incompletely replicated the internal fibrillar structure that dictates fiber mechanical and biological properties. We report a continuous extrusion system with an off-line phosphate buffer incubation step for the manufacture of synthetic collagen fiber. Fiber with a cross-section of 53+ or - 14 by 21 + or - 3 microm and an ultimate tensile strength of 94 + or - 19 MPa was continuously produced at 60 m/hr from an ultrafiltered monomeric collagen solution. The effect of collagen solution concentration, flow rate, and spinneret size on fiber size was investigated. The fiber was further characterized by microdifferential scanning calorimetry, transmission electron microscopy (TEM), second harmonic generation (SHG) analysis, and in a subcutaneous murine implant model. Calorimetry demonstrated stabilization of the collagen triple helical structure, while TEM and SHG revealed a dense, axially aligned D-periodic fibril structure throughout the fiber cross-section. Implantation of glutaraldehyde crosslinked and noncrosslinked fiber in the subcutaneous tissue of mice demonstrated limited inflammatory response and biodegradation after a 6-week implant period. PMID:20024969

  5. Fibrillogenesis in Continuously Spun Synthetic Collagen Fiber

    PubMed Central

    Caves, Jeffrey M.; Kumar, Vivek A.; Wen, Jing; Cui, Wanxing; Martinez, Adam; Apkarian, Robert; Coats, Julie E.; Berland, Keith; Chaikof, Elliot L.

    2013-01-01

    The universal structural role of collagen fiber networks has motivated the development of collagen gels, films, coatings, injectables, and other formulations. However, reported synthetic collagen fiber fabrication schemes have either culminated in short, discontinuous fiber segments at unsuitably low production rates, or have incompletely replicated the internal fibrillar structure that dictates fiber mechanical and biological properties. We report a continuous extrusion system with an off-line phosphate buffer incubation step for the manufacture of synthetic collagen fiber. Fiber with a cross-section of 53±14 by 21±3 µm and an ultimate tensile strength of 94±19 MPa was continuously produced at 60 m/hr from an ultrafiltered monomeric collagen solution. The effect of collagen solution concentration, flow rate, and spinneret size on fiber size was investigated. The fiber was further characterized by microdifferential scanning calorimetry, transmission electron microscopy (TEM), second harmonic generation (SHG) analysis, and in a subcutaneous murine implant model. Calorimetry demonstrated stabilization of the collagen triple helical structure, while TEM and SHG revealed a dense, axially aligned D-periodic fibril structure throughout the fiber cross-section. Implantation of glutaraldehyde crosslinked and non-crosslinked fiber in the subcutaneous tissue of mice demonstrated limited inflammatory response and biodegradation after a 6-week implant period. PMID:20024969

  6. Engineering a resonant nanocoating for an optical refractive index sensor

    NASA Astrophysics Data System (ADS)

    Bialiayeu, A.; Ianoul, A.; Albert, J.

    2014-03-01

    We proposing to boost the performance of refractive index sensors based on the tilted fiber Bragg grating (TFBG) structure by resonant coupling of small spherical nanoparticles to the TFBG resonances. The optimal choice of nanoparticle parameters is discussed.

  7. Exposed-core chalcogenide microstructured optical fibers for chemical sensing

    NASA Astrophysics Data System (ADS)

    Troles, Johann; Toupin, Perrine; Brilland, Laurent; Boussard-Plédel, Catherine; Bureau, Bruno; Cui, Shuo; Mechin, David; Adam, Jean-Luc

    2013-05-01

    Chemical bonds of most of the molecules vibrate at a frequency corresponding to the near or mid infrared field. It is thus of a great interest to develop sensitive and portable devices for the detection of specific chemicals and biomolecules for various applications in health, the environment, national security and so on. Optical fibers define practical sensing tools. Chalcogenide glasses are known for their transparency in the infrared optical range and their ability to be drawn as fibers. They are consequently good candidates to be used in biological/chemical sensing. For that matter, in the past decade, chalcogenide glass fibers have been successfully implemented in evanescent wave spectroscopy experiments, for the detection of bio-chemical species in various fields of applications including microbiology and medicine, water pollution and CO2 detection. Different types of fiber can be used: single index fibers or microstructured fibers. Besides, in recent years a new configuration of microstructured fibers has been developed: microstructured exposed-core fibers. This design consists of an optical fiber with a suspended micron-scale core that is partially exposed to the external environment. This configuration has been chosen to elaborate, using the molding method, a chalcogenide fiber for chemical species detection. The sensitivity of this fiber to detect molecules such as propan-2-ol and acetone has been compared with those of single index fibers. Although evanescent wave absorption is inversely proportional to the fiber diameter, the result shows that an exposed-core fiber is much more sensitive than a single index fiber having a twice smaller external diameter.

  8. Miniature fiber optic surface plasmon resonance biosensors

    NASA Astrophysics Data System (ADS)

    Slavik, Radan; Brynda, Eduard; Homola, Jiri; Ctyroky, Jiri

    1999-01-01

    A novel design of surface plasmon resonance fiber optic sensor is reported which leads to a compact, highly miniaturized sensing element with excellent sensitivity. The sensing device is based on a side-polished single-mode optical fiber with a thin metal overlayer supporting surface plasmon waves. The strength of interaction between a fiber mode and a surface plasmon wave depends strongly on the refractive index near the sensing surface. Therefore, refractive index changes associated with biospecific interaction between antibodies immobilized on the sensor and antigen molecules can be monitored by measuring light intensity variations. Detection of horse radish peroxidase (HRP) of the concentration of 100 ng/ml has been accomplished using the fiber optic sensor with a matrix of monoclonal antibodies against HRP immobilized on the sensor surface.

  9. Photonic lantern with cladding-removable fibers

    NASA Astrophysics Data System (ADS)

    Sun, Weimin; Yan, Qi; Bi, Yao; Yu, Haijiao; Liu, Xiaoqi; Xue, Jiuling; Tian, He; Liu, Yongjun

    2014-07-01

    Recently, spectral measurement becomes an important tool in astronomy to find exoplanets etc. The fibers are used to transfer light from the focal plate to spectrometers. To get high-resolution spectrum, the input slits of the spectrometers should be as narrow as possible. In opposite, the light spots from the fibers are circle, which diameters are clearly wider than the width of the spectrometer slits. To reduce the energy loss of the fiber-guide star light, many kinds of image slicers were designed and fabricated to transform light spot from circle to linear. Some different setup of fiber slicers are introduced by different research groups around the world. The photonic lanterns are candidates of fiber slicers. Photonic lantern includes three parts: inserted fibers, preform or tubing, taped part of the preform or tubing. Usually the optical fields concentrate in the former-core area, so the light spots are not uniform from the tapered end of the lantern. We designed, fabricated and tested a special kind of photonic lantern. The special fibers consist polymer cladding and doped high-index core. The polymer cladding could be easily removed using acetone bath, while the fiber core remains in good condition. We inserted the pure high-index cores into a pure silica tubing and tapered it. During the tapering process, the gaps between the inserted fibers disappeared. Finally we can get a uniform tapered multimode fiber end. The simulation results show that the longer the taper is, the lower the loss is. The shape of the taper should be controlled carefully. A large-zone moving-flame taper machine was fabricated to make the special photonic lantern. Three samples of photonic lanterns were fabricated and tested. The lanterns with cladding-removable fibers guide light uniform in the tapered ends that means these lanterns could collect more light from those ends.

  10. Jung Index

    NSDL National Science Digital Library

    1999-01-01

    Compiled by Matthew Clapp of the University of Georgia, the Jung Index is a collection of more than 300 online resources about and related to the life and work of Carl Jung, the Swiss psychologist and psychiatrist who founded analytic psychology. Resources are indexed into ten major topic areas and include sections such as Research Resources, Jungian Psychology, and Psychoanalysis, among others. A What's New? section, a What's Cool? section, and the JungNet Newsletter keep frequent visitors up to date on the latest and greatest resources in analytic psychology. In addition, the site provides a glossary of Jungian terms, a gallery of Jungian images, and a moderated forum for Jungian discussion.

  11. New Developments in Elastic Fibers

    Microsoft Academic Search

    Jinlian Hu; Jing Lu; Yong Zhu

    2008-01-01

    This paper reviews the developments of essential elastic fibers. The elastic fibers include extensible polymer fibers with low or high elasticity and reversibility which consists of the polyurethane elastic fiber, polyester?ether elastic fiber, polyester elastic fiber, olefin based elastic fiber like XLA, hard elastic fiber, bio?component fiber, and the shape memory fibers. The emphasis of the review is on the

  12. Dietary Carbohydrates, Fiber, and Breast Cancer Risk

    Microsoft Academic Search

    Michelle D. Holmes; Simin Liu; Susan E. Hankinson; Graham A. Colditz; David J. Hunter; Walter C. Willett

    2004-01-01

    Dietary fiber, fiber fractions, carbohydrate, glycemic index, and glycemic load were prospectively assessed five times over 18 years with a validated food frequency questionnaire in relation to breast cancer risk among 88,678 women (aged 34-59 years at baseline) in the Nurses' Health Study. Incident breast cancer occurred in 4,092 of these women between 1980 and 1998. The authors observed no

  13. Photonic band gap guidance in optical fibers

    PubMed

    Knight; Broeng; Birks; Russell

    1998-11-20

    A fundamentally different type of optical waveguide structure is demonstrated, in which light is confined to the vicinity of a low-index region by a two-dimensional photonic band gap crystal. The waveguide consists of an extra air hole in an otherwise regular honeycomb pattern of holes running down the length of a fine silica glass fiber. Optical fibers based on this waveguide mechanism support guided modes with extraordinary properties. PMID:9822375

  14. Endlessly single-mode photonic crystal fiber.

    PubMed

    Birks, T A; Knight, J C; Russell, P S

    1997-07-01

    We made an all-silica optical fiber by embedding a central core in a two-dimensional photonic crystal with a micrometer-spaced hexagonal array of air holes. An effective-index model confirms that such a fiber can be single mode for any wavelength. Its useful single-mode range within the transparency window of silica, although wide, is ultimately bounded by a bend-loss edge at short wavelengths as well as at long wavelengths. PMID:18185719

  15. Adaptive control in optical fibers

    SciTech Connect

    Omenetto, F. G. (Fiorenzo G.)

    2002-01-01

    Adpative control in combination with ultrafast pulse shaping provides a compelling approach to defeat dispersion, distortion and harness nonlinear phenomena on the femtosecond timescale. Ultrafast pulses propagating in optical fibers generate a number of linear and nonlinear effects which affect the pulse during its travel. The main causes stem from the dependence of the index of refraction on frequency (given that short pulses have a large bandwidth) and from the so-called self-action effects which involve the dependence of the index of refraction on the pulse intensity (which is high given that the pulse energy is confined to a very short amount of time).

  16. Intrinsic Fabry-Perot optical fiber sensors and their multiplexing

    DOEpatents

    Wang, Anbo (Blacksburg, VA)

    2007-12-11

    An intrinsic Fabry-Perot optical sensor includes a thin film sandwiched between two fiber ends. When light is launched into the fiber, two reflections are generated at the two fiber/thin film interfaces due to a difference in refractive indices between the fibers and the film, giving rise to the sensor output. In another embodiment, a portion of the cladding of a fiber is removed, creating two parallel surfaces. Part of the evanescent fields of light propagating in the fiber is reflected at each of the surfaces, giving rise to the sensor output. In a third embodiment, the refractive index of a small portion of a fiber is changed through exposure to a laser beam or other radiation. Interference between reflections at the ends of the small portion give rise to the sensor output. Multiple sensors along a single fiber are multiplexed using an optical time domain reflectometry method.

  17. Photovoltaic fibers

    NASA Astrophysics Data System (ADS)

    Gaudiana, Russell; Eckert, Robert; Cardone, John; Ryan, James; Montello, Alan

    2006-08-01

    It was realized early in the history of Konarka that the ability to produce fibers that generate power from solar energy could be applied to a wide variety of applications where fabrics are utilized currently. These applications include personal items such as jackets, shirts and hats, to architectural uses such as awnings, tents, large covers for cars, trucks and even doomed stadiums, to indoor furnishings such as window blinds, shades and drapes. They may also be used as small fabric patches or fiber bundles for powering or recharging batteries in small sensors. Power generating fabrics for clothing is of particular interest to the military where they would be used in uniforms and body armor where portable power is vital to field operations. In strong sunlight these power generating fabrics could be used as a primary source of energy, or they can be used in either direct sunlight or low light conditions to recharge batteries. Early in 2002, Konarka performed a series of proof-of-concept experiments to demonstrate the feasibility of building a photovoltaic cell using dye-sensitized titania and electrolyte on a metal wire core. The approach taken was based on the sequential coating processes used in making fiber optics, namely, a fiber core, e.g., a metal wire serving as the primary electrode, is passed through a series of vertically aligned coating cups. Each of the cups contains a coating fluid that has a specific function in the photocell. A second wire, used as the counter electrode, is brought into the process prior to entering the final coating cup. The latter contains a photopolymerizable, transparent cladding which hardens when passed through a UV chamber. Upon exiting the UV chamber, the finished PV fiber is spooled. Two hundred of foot lengths of PV fiber have been made using this process. When the fiber is exposed to visible radiation, it generates electrical power. The best efficiency exhibited by these fibers is 6% with an average value in the 4-5 % range.

  18. Consumption of total fiber and types of fiber are associated with a lower prevalence of obesity and abdominal adiposity in US adults. NHANES 1999-2006.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this cross-sectional study, an inverse association was found between intakes of total dietary fiber and five types of fiber with Body Mass Index, waist circumference, and percent obese, and with increased waist circumference. Intake of vegetable fiber was not associated with any of the weight mea...

  19. Solving Single Step Equations

    NSDL National Science Digital Library

    Ms. Reddish

    2011-09-30

    This is to practice and review single step equations. Have fun. Complete the following two sites. Follow the directions given for each site. One-Step Equations Add/Subtract One-Step Equations Mult/Division When you have finished the sites above, enter equation buster and work through level one. Equation buster ...

  20. A Step Circuit Program.

    ERIC Educational Resources Information Center

    Herman, Susan

    1995-01-01

    Aerobics instructors can use step aerobics to motivate students. One creative method is to add the step to the circuit workout. By incorporating the step, aerobic instructors can accommodate various fitness levels. The article explains necessary equipment and procedures, describing sample stations for cardiorespiratory fitness, muscular strength,…

  1. Population Index

    NSDL National Science Digital Library

    Two excellent bibliographic resources for population studies are the "Population Index" from the Office of Population Research at Princeton University, and "Population Organizations: Finder's Guide" from the Center for Demography and Ecology at the University of Wisconsin-Madison. "Population Index" is a quarterly publication that has been available since 1935. It "covers all fields of interest to demographers, including fertility, mortality, population size and growth, migration, nuptiality and the family, research methodology, projections and predictions, historical demography, and demographic and economic interrelations. Input is derived from original publications including monographs, journal articles, other serial publications, working papers, doctoral dissertations, machine-readable data files, and relevant acquisitions lists and bibliographies." About 3,500 citations are produced annually. Full text for the Index is available at the "Population Index" Web site for 1986-present (Vol. 52-present). Indexes can be searched by author, subject matter, geographical region, or publication year. There is now an experimental free text search capability for the 1994-present issues. "Population Organizations: Finder's Guide" is a no frills "practical tool for population professionals who need a single source for the quick location of organizations that publish and distribute or post population or family planning documents." It contains hundreds of citations, providing organization addresses, phone and FAX numbers, and Internet addresses when available. The Guide is updated every six months and is maintained by Ruth Sandor, Director of the Library of the Center for Demography and Ecology. Office of Population Research, Princeton University: http://opr.princeton.edu/ "Population Organizations: Finder's Guide": gopher://cde2.ssc.wisc.edu:70/00/addazlis gopher to: cde2.ssc.wisc.edu select: Population Organizations: Finder's Guide Center for Demography and Ecology, University of Wisconsin-Madison: http://www.ssc.wisc.edu/cde/

  2. Diamond chemical vapor deposition on optical fibers for fluorescence waveguiding

    E-print Network

    J. R. Rabeau; S. T. Huntington; A. D. Greentree; S. Prawer

    2004-11-10

    A technique has been developed for depositing diamond crystals on the endfaces of optical fibers and capturing the fluorescence generated by optically active defects in the diamond into the fiber. This letter details the diamond growth on optical fibers and transmission of fluorescence through the fiber from the nitrogen-vacancy (N-V) color center in diamond. Control of the concentration of defects incorporated during the chemical vapor deposition (CVD) growth process is also demonstrated. These are the first critical steps in developing a fiber coupled single photon source based on optically active defect centers in diamond.

  3. Programmable optic-fiber delay line

    E-print Network

    Fang, Shin-Puu

    1991-01-01

    delay times. Journal model is IEEE Journal of Lighhoave Technology. Substrate Modulated Single Mode Laser Diode Fiber Reels Q L=Lp Lt=2 Lp O Switch L2 =2 Lp 2 Ls =2 Lp Photodector 2X1 Coupler 1(a) Delayed Signal Out Inputs Outputs Straight...B per switch). In Figure 2 is illustrated a design for an all-fiber switch made with two 50:50 single-mode directional couplers which form a Mach-Zender interferometer. A heater is provided for one of the two fiber arms to change the refractive index...

  4. Nonadiabatic tapered optical fiber for biosensor applications

    NASA Astrophysics Data System (ADS)

    Latifi, Hamid; Zibaii, Mohammad I.; Hosseini, Seyed M.; Jorge, Pedro

    2012-12-01

    A brief review on biconical tapered fiber sensors for biosensing applications is presented. A variety of configurations and formats of this sensor have been devised for label free biosensing based on measuring small refractive index changes. The biconical nonadiabatic tapered optical fiber offers a number of favorable properties for optical sensing, which have been exploited in several biosensing applications, including cell, protein, and DNA sensors. The types of these sensors present a low-cost fiber biosensor featuring a miniature sensing probe, label-free direct detection, and high sensitivity.

  5. Ultrasensitive fiber optic sensors and their applications

    NASA Astrophysics Data System (ADS)

    Nam, SungHyun; Lee, Jon; Yin, Shizhuo; Reichard, Karl; Ruffin, Paul; Wang, Qing

    2005-03-01

    In this paper, a brief review on ultrasensitive fiber optic sensors and their applications, done recently at Penn State, is presented. Our discussions will mainly focus on two types of highly sensitive fiber optic sensors. One type is based on the combination of single resonant band long period gratings (LPGs) with the second refractive index matched polymer cladding layer. The other one is based on the LPGs fabricated in photonic nanostructured fibers and waveguides. It is found that a significantly increased sensitivity (two order plus) can be achieved by harnessing these approaches, which will benefit a variety of applications, in particular, low concentration chemical/biological agents detection.

  6. Optical fibers for high-resolution in vivo microendoscopic fluorescence imaging

    NASA Astrophysics Data System (ADS)

    Oh, Gyungseok; Chung, Euiheon; Yun, Seok H.

    2013-12-01

    Optical fiber-based high-resolution fluorescence imaging techniques have promising applications in clinical practice and preclinical research using animals. Here we review the instrumentation and applications of microendoscopy based on various types of optical fibers. Single-mode fibers and double-clad fibers have been widely used for delivering light from light sources to tissues and collecting light from tissues to photodetectors. Coherent fiber bundles, cylindrical graded-index lenses, and multi-mode fibers have been employed in both beam-scanning and non-scanning microscopy. With continuing advances of optical fiber technologies, further innovations in optical microendoscopy are expected.

  7. Fiber optic sensors focus on smart systems

    Microsoft Academic Search

    Raymond M. Measures; Kexing Liu

    1992-01-01

    Materials with structurally integrated fiber-optic sensors, the first step toward smart structures, which continuously monitor their own vibration, internal strain and deformation, temperature, and structural integrity are described. It is shown that the Fabry-Perot fiber-optic strain sensor has capabilities that far exceed those of conventional foil strain gauges, which holds the promise of responding to acoustic emission signals while simultaneously

  8. JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 28, NO. 4, FEBRUARY 15, 2010 1 Fiber-Wireless Networks and

    E-print Network

    Bakaul, Masuduzzaman

    fuelled by the maturing and more reliable digital and RF circuit fabrica- tion and miniaturization. Index Terms--Fiber-wireless, microwave photonics, op- tical-wireless integration, radio-over-fiber. I

  9. Integrated fiber optic probe for dynamic light scattering

    NASA Technical Reports Server (NTRS)

    Dhadwal, Harbans S.; Khan, Romel R.; Suh, Kwang

    1993-01-01

    An integrated fiber optic probe, comprising a monomode optical fiber fusion spliced to a short length of a graded-index multimode fiber, is fabricated for use as a coherent receiver in dynamic light scattering. The multimode fiber is cleaved to provide a gradient-index fiber lens with a focal length of 125 microns and an f-number close to unity. An integrated fiber receiver is used to measure the intensity-intensity autocorrelation data from a 0.05 percent by weight concentration of an aqueous suspension of polystyrene latex spheres. Analysis of 100 independent data sets indicates that the particle size can be recovered with an accuracy of +/- 1 percent.

  10. Optimization of fiber shapes in biocomposites

    NASA Astrophysics Data System (ADS)

    Zhou, Yan

    Fibers can be used to improve the mechanical properties of acrylic bone cement. However, debonding of the fibers from the matrix due to the poor fiber/matrix interface is a major failure mechanism for such reinforcements. Optimization of the fiber shape can improve load transfer between the fibers and the matrix, thereby providing improved overall mechanical performance. The goals of this study include: (1) Develop an analytical model to evaluate the effects of fiber end geometry on the pullout load and stress distribution; (2) Determine the optimal fiber morphology for maximum stress transfer in composites using optimization and finite element modeling; (3) Fabricate the fibers with optimal morphology determined by the previous step; (4) Manufacture composites reinforced with the optimized fibers and demonstrate improved mechanical properties experimentally. Analytical solutions were derived to predict the effects of the enlarged end shape on the pullout load and stress distribution. It is shown that the shape of the enlarged end has a significant influence on the stress distribution of the short fiber. A procedure for structural shape optimization of short fibers was developed. The effects of the interfacial bond and fiber orientation were investigated to obtain the optimal fiber shape. The general optimal fiber shape is a variable diameter fiber (VDF). Due to the mechanical interlock, the VDF can both bridge matrix cracks effectively and improve the composite mechanical properties. Ceramic VDFs were successfully fabricated. Static and fatigue tests were carried out on the VDF reinforced composites. Conventional straight fiber (CSF) reinforced bone cement was also tested for comparison purposes. Results demonstrated that both the stiffness and the fatigue life of VDF reinforced bone cement are significantly improved compared with the unreinforced cement. Also, the fatigue life of VDF reinforced bone cement was significantly longer than that of CSF reinforced cement. This study shows the feasibility of a novel fiber (VDFs) technology for reinforced polymers. This fiber family significantly improves the fatigue life of bone cement at a very high level of reliability. VDFs could potentially avoid implant loosening due to the mantle fracture of bone cement and delay the need for revision surgery.

  11. Advanced CSS Layouts: Step by Step

    NSDL National Science Digital Library

    King, Andy.

    Most Web sites are designed with HTML tables, which can be an arduous task. Making sites that are accessible and standards-compliant requires a separation of markup and content, and CSS is the best way to accomplish this. This Web page by Rogelio Vizcaino Lizaola and Andy King offers a step-by-step CSS layout tutorial on how to create WebReference table-like layouts (that behave well with small window sizes and large fonts), while avoiding some of the bugs and problems discovered in other implementations. Target browsers include all of the generation five and greater browsers on both Windows and Macintosh platforms.

  12. Evaluation of Small Form Factor Fiber Optic Interconnects for the NASA Electronics Parts and Packaging Program (NEPP)

    NASA Technical Reports Server (NTRS)

    Ott, Melanie; Thomes, W. Joe; Blair, Diana; Chuska, Rick; Switzer, Rob

    2010-01-01

    The Diamond AVIM optical fiber connector has been used for over a decade in flight environments. AVIM which stands for Aviation Intermediate Maintenance is always referenced as a fiber optic connector type from the DIN (Deutsches Institut fur Normung) family of optical fiber connectors. The newly available Mini AVIM and DMI (Definition Multimedia Interface) connectors also by Diamond provide similar features as the high performance AVIM with the added benefits of being small form factor for board mount and internal box use where long connectors and strain relief can not be accommodated. Transceiver, fiber laser technology and receiver optic technology based on small sized constraints will benefit the most by the reduction in connector form factor. It is for this reason that the Mini AVIM is being evaluated for multimode and single mode optical fiber use in both fiber based and cable based packaging configurations. In a fiber based termination, there are no cable materials to bond to the connector. The only bonding that is conducted is the mounting of the fiber with epoxy to the connector ferrules (which are called DMI ferrules). In a cable configuration, the compatibility of the connector subcomponents along with the upjacketing materials of the cable around the fiber needs to be considered carefully for termination fabrication. Cabled terminations will show greater insertion loss and high probability of failures during thermal cycling testing. This is due to the stressing of the combination of materials that each have different Coefficients of Thermal Expansion (CTE's) and that are bonded together to the connector subcomponents. As the materials flex during thermal excursions, forces are applied to the termination and can make the system fail if the grouping of materials (per their CTE's) are not compatible and this includes cable materials, epoxies, ferrule and connector body components. For this evaluation, multimode 100 micron core step index fiber was used for the fiber terminated condition, and single mode SMF-28 upjacketed with W.L. Gore Flexlite was used for the cabled configuration. For background purposes, a comparison is presented here for information purposes between the high performance AVIM connector features and the Mini AVIM small form factor connectors. Basic connector features are described here.

  13. Monolithic silicon photonic crystal slab fiber tip sensor

    Microsoft Academic Search

    Il Woong Jung; Bryan Park; J. Provine; Roger T. Howe; Olav Solgaard

    2009-01-01

    We demonstrate that monolithic photonic crystals (PCs) confined to the facet, or tip, of single-mode optical fibers can be designed as highly sensitive refractive index point sensors. Monolithic photonic-crystal slabs are fabricated on silicon wafers and subsequently released and micro-assembled on the tip of optical fibers. The PC slab's reflection spectrum is modulated by the refractive index of the environment

  14. Evaluation of the performance of polypropylene fibers on soil stabilization

    E-print Network

    Sangineni, Srinivas Meherji

    1992-01-01

    -term reactions. Immediate reactions improve workability, reduce shrink-swell, reduce the plasticity index of soil, and increase shear strength. Long-term reactions increase shear, tensile, and flexural strengths, make the material more brittle, and increase... and No Polypropylene Fibers (12). 35 Figure 7 Energy Absorbed in Instrumented Impact Testing of Polypropylene Fiber-Reinforced Concrete Beams as a Function of Fiber Volume Fraction and Size (25). 39 Figure 8. Moisture-Density Curves for Sand, Without Cement...

  15. A two-mode fiber optic-bending sensor 

    E-print Network

    Covington, Charles Eric

    1993-01-01

    It is shown that a small slope in the refractive index profile of an optical fiber causes the two lowest order spatial modes to travel different distances from the geometrical center of the fiber. This effect increases by orders of magnitude...

  16. Photonic bandgap fiber-based Surface Plasmon Resonance sensors.

    PubMed

    Gauvreau, Bertrand; Hassani, Alireza; Fassi Fehri, Majid; Kabashin, Andrei; Skorobogatiy, Maksim A

    2007-09-01

    The concept of photonic bandgap fiber-based surface plasmon resonance sensor operating with low refractive index analytes is developed. Plasmon wave on the surface of a thin metal film embedded into a fiber microstructure is excited by a leaky Gaussian-like core mode of a fiber. We demonstrate that by judicious design of the photonic crystal reflector, the effective refractive index of the core mode can be made considerably smaller than that of the core material, thus enabling efficient phase matching with a plasmon, high sensitivity, and high coupling efficiency from an external Gaussian source, at any wavelength of choice from the visible to near-IR. To our knowledge, this is not achievable by any other traditional sensor design. Moreover, unlike the case of total internal reflection waveguide-based sensors, there is no limitation on the upper value of the waveguide core refractive index, therefore, any optical materials can be used in fabrication of photonic bandgap fiber-based sensors. Based on numerical simulations, we finally present designs using various types of photonic bandgap fibers, including solid and hollow core Bragg fibers, as well as honeycomb photonic crystal fibers. Amplitude and spectrum based methodologies for the detection of changes in the analyte refractive index are discussed. Furthermore, sensitivity enhancement of a degenerate double plasmon peak excitation is demonstrated for the case of a honeycomb fiber. Sensor resolutions in the range 7 * 10(-6) -5 * 10(-5) RIU were demonstrated for an aqueous analyte. PMID:19547499

  17. Stimulated Raman scattering in an ethanol core microstructured optical fiber

    E-print Network

    Paris-Sud XI, Université de

    -Filled Hollow-Core Photonic Crystal Fiber" Science, 298, 399 (2002) 17. F. Benabid, F. Couny, J. C. Knight, T. A crystal fiber with the core filled with a low refractive index nonlinear liquid. This new architecture,P.J. Roberts, P. S.J. Russell, D.M. Atkin, T.J. Shepherd, "Full 2-D photonic bandgaps in silica/air structures

  18. Silicone polymer waveguide bridge for Si to glass optical fibers

    NASA Astrophysics Data System (ADS)

    Kruse, Kevin L.; Riegel, Nicholas J.; Middlebrook, Christopher T.

    2015-03-01

    Multimode step index polymer waveguides achieve high-speed, (<10 Gb/s) low bit-error-rates for onboard and embedded circuit applications. Using several multimode waveguides in parallel enables overall capacity to reach beyond 100 Gb/s, but the intrinsic bandwidth limitations due to intermodal dispersion limit the data transmission rates within multimode waveguides. Single mode waveguides, where intermodal dispersion is not present, have the potential to further improve data transmission rates. Single mode waveguide size is significantly less than their multimode counterparts allowing for greater density of channels leading to higher bandwidth capacity per layer. Challenges in implementation of embedded single mode waveguides within printed circuit boards involves mass production fabrication techniques to create precision dimensional waveguides, precision alignment tolerances necessary to launch a mode, and effective coupling between adjoining waveguides and devices. An emerging need in which single mode waveguides can be utilized is providing low loss fan out techniques and coupling between on-chip transceiver devices containing Si waveguide structures to traditional single mode optical fiber. A polymer waveguide bridge for Si to glass optical fibers can be implemented using silicone polymers at 1310 nm. Fabricated and measured prototype devices with modeling and simulation analysis are reported for a 12 member 1-D tapered PWG. Recommendations and designs are generated with performance factors such as numerical aperture and alignment tolerances.

  19. Temperature-independent polymer optical fiber evanescent wave sensor.

    PubMed

    Zhong, Nianbing; Liao, Qiang; Zhu, Xun; Zhao, Mingfu; Huang, Yun; Chen, Rong

    2015-01-01

    Although the numerous advantages of polymer optical fibers have been exploited in the fields of sensors and telecommunications, such fibers still experience a critical problem: the temperature dependency. Therefore, we explored the temperature-independent operation of a polymer fiber-optic evanescent wave sensor immersed in distilled water. We investigated variations in the surface morphology, deformation trajectory, refractive index, and weight of the fiber-sensing region with varying water temperature. We also examined the spectral transmission and transmitted light intensity of fibers subjected to a heating-cooling treatment. We observed that the light-transmission modes and sensitivity of the sensor were affected by changes in the surface morphology, diameter, and refractive index of the sensing region caused by changes in temperature. The transmitted light intensity of the sensor was maintained at a constant level after five cycles of the heating-cooling treatment, after which the fibers exhibited a smooth surface, low refractive index, and large fiber diameter. Consequently, we utilized the heating-cooling-treated fiber to realize a temperature-independent, U-shaped polymer fiber-optic evanescent wave sensor. The temperature independence was evaluated using glucose solutions in the range of 10 to 70?°C. The fabricated sensor showed significant temperature independence and high degree of consistency in measuring solutions. PMID:26112908

  20. Temperature-independent polymer optical fiber evanescent wave sensor

    PubMed Central

    Zhong, Nianbing; Liao, Qiang; Zhu, Xun; Zhao, Mingfu; Huang, Yun; Chen, Rong

    2015-01-01

    Although the numerous advantages of polymer optical fibers have been exploited in the fields of sensors and telecommunications, such fibers still experience a critical problem: the temperature dependency. Therefore, we explored the temperature-independent operation of a polymer fiber-optic evanescent wave sensor immersed in distilled water. We investigated variations in the surface morphology, deformation trajectory, refractive index, and weight of the fiber-sensing region with varying water temperature. We also examined the spectral transmission and transmitted light intensity of fibers subjected to a heating-cooling treatment. We observed that the light-transmission modes and sensitivity of the sensor were affected by changes in the surface morphology, diameter, and refractive index of the sensing region caused by changes in temperature. The transmitted light intensity of the sensor was maintained at a constant level after five cycles of the heating-cooling treatment, after which the fibers exhibited a smooth surface, low refractive index, and large fiber diameter. Consequently, we utilized the heating-cooling-treated fiber to realize a temperature-independent, U-shaped polymer fiber-optic evanescent wave sensor. The temperature independence was evaluated using glucose solutions in the range of 10 to 70?°C. The fabricated sensor showed significant temperature independence and high degree of consistency in measuring solutions. PMID:26112908

  1. Thermooptically tunable side-polished fiber comb filter and its application

    Microsoft Academic Search

    Kyung-Rak Sohn; Jae-Won Song

    2002-01-01

    Tunable side-polished fiber comb filters based on the thermooptic effect of a polymer layer inserted between a side-polished fiber and an overlay waveguide are presented. The thermal electrodes formed on a polymer layer control the refractive index of one and its index variation induces the shift in coupling wavelength by the phase change of an evanescent field at the overlay

  2. Optical Home Network based on an NxN Multimode Fiber Architecture and CWDM Technology

    E-print Network

    Paris-Sud XI, Université de

    Optical Home Network based on an NxN Multimode Fiber Architecture and CWDM Technology F. Richard(1 these applications. Considering the large bandwidth which will be then required, optical fiber appears to be the only (CWDM) technology is mature. In this paper, we focus on silica graded index multimode fiber (MMF

  3. TESLA Report No. 2000-26 September 2000 Fiber Optic Radiation Sensing Systems

    E-print Network

    TESLA Report No. 2000-26 September 2000 Fiber Optic Radiation Sensing Systems for TESLA by H, Germany F. Wulf Hahn-Meitner-Institut HMI, Germany #12;Fiber Optic Radiation Sensing Systems for TESLA of refractive index at high radiation doses 4 3. Fiber optic dosimeter types for different TESLA sections 4 3

  4. Simultaneous generation of spectrally distinct third harmonic in photonic crystal fibers

    Microsoft Academic Search

    F. G. Omenetto; M. D. Moores; D. H. Reitze; J. C. Knight; W. J. Wadsworth; P.St.J. Russell; A. J. Taylor

    2001-01-01

    Summary form only given. Recently, photonic crystal fibers have attracted considerable interest for their unique structure and optical properties. These fibers contain an ordered array of air holes which form a low-index cladding around a solid silica core. Other examples include fibers with hollow cores where light is guided by a photonic bandgap effect. Understanding the propagation of fs pulses

  5. Investigation of long-period fiber gratings induced by high-intensity femtosecond UV laser pulses

    E-print Network

    Nikogosyan, David N.

    Investigation of long-period fiber gratings induced by high-intensity femtosecond UV laser pulses,5]. Such UV laser irradiation led to a refractive index change in the Ge-doped fiber core via a single changes in the fiber core induced by thermal heating, were developed. They include the use of a CO2 laser

  6. Phase and amplitude control of a multimode LMA fiber beam by use of digital holography

    E-print Network

    Boyer, Edmond

    in a self-aligned gradient- index Brillouin cavity for high-power multimode fiber amplifiers," Opt. Lett. 31Phase and amplitude control of a multimode LMA fiber beam by use of digital holography M. Paurisse1 of a multimode LMA fiber supporting 4 modes is demonstrated by digital holography in both continuous and ns

  7. Bent-fiber intermodal interference based dual-channel fiber optic refractometer.

    PubMed

    Zhang, Xinpu; Peng, Wei

    2015-03-23

    We present a novel dual-channel fiber optic interferometer based on intermodal interference from single-mode fiber (SMF) bending. This dual-channel interferometer has simple structure, consisting of two bare fiber semicircular bending regions with different bending radiuses connected by a section of straight fiber. A dual-channel interferometer with bending radiuses of 4 mm and 4.3 mm is fabricated and refractive index (RI) sensing is realized by measuring the wavelength shift of the resonance dips in the transmission spectrum of the dual-channel interferometer. In the RI range of 1.3403 to 1.3726, the corresponding RI sensitivities for these two channels are 207 and 245 nm/RIU (refractive index unit) and the RI resolutions are about 6.57 × 10?? RIU and 5.55 × 10?? RIU, respectively. PMID:25837098

  8. Indexing and Querying Avishek Anand

    E-print Network

    Nejdl, Wolfgang

    Indexing and Querying Avishek Anand #12;Avishek Anand Inverted Indexing basics revisited Indexing Static Collections Dictionaries Forward Index Inverted Index Organisation Scalable Indexing Indexing Dynamic Collections Inverted Index Construction and Maintenance 2 #12;Avishek Anand

  9. Accurate numerical simulation of short fiber optical parametric amplifiers.

    PubMed

    Marhic, M E; Rieznik, A A; Kalogerakis, G; Braimiotis, C; Fragnito, H L; Kazovsky, L G

    2008-03-17

    We improve the accuracy of numerical simulations for short fiber optical parametric amplifiers (OPAs). Instead of using the usual coarse-step method, we adopt a model for birefringence and dispersion which uses fine-step variations of the parameters. We also improve the split-step Fourier method by exactly treating the nonlinear ellipse rotation terms. We find that results obtained this way for two-pump OPAs can be significantly different from those obtained by using the usual coarse-step fiber model, and/or neglecting ellipse rotation terms. PMID:18542454

  10. Fiber optic cable connector

    Microsoft Academic Search

    J. E. Ludman; J. L. Horner; H. J. Caulfield

    1986-01-01

    A fiber optic cable connector for coupling together a pair of optical fibers having a pair of fixtures, each of the fixtures securing therein a respective optical fiber and having magnification lens optically aligned with the end of the optical fiber. The lens and fibers are so positioned relative to each other so as to focus a magnified or enlarged

  11. Microbend fiber-optic temperature sensor

    DOEpatents

    Weiss, J.D.

    1995-05-30

    A temperature sensor is made of optical fiber into which quasi-sinusoidal microbends have been permanently introduced. In particular, the present invention includes a graded-index optical fiber directing steady light through a section of the optical fiber containing a plurality of permanent microbends. The microbend section of the optical fiber is contained in a thermally expansive sheath, attached to a thermally expansive structure, or attached to a bimetallic element undergoing temperature changes and being monitored. The microbend section is secured to the thermally expansive sheath which allows the amplitude of the microbends to decrease with temperature. The resultant increase in the optical fiber`s transmission thus allows temperature to be measured. The plural microbend section of the optical fiber is secured to the thermally expansive structure only at its ends and the microbends themselves are completely unconstrained laterally by any bonding agent to obtain maximum longitudinal temperature sensitivity. Although the permanent microbends reduce the transmission capabilities of fiber optics, the present invention utilizes this phenomenon as a transduction mechanism which is optimized to measure temperature. 5 figs.

  12. Impact of fiber core diameter on dispersion and multiplexing in multimode-fiber links.

    PubMed

    Appaiah, Kumar; Vishwanath, Sriram; Bank, Seth R

    2014-07-14

    Large-core silica multimode fibers, whose core diameters are generally 50 ?m or 62.5 ?m, form the bulk of short and medium haul optical fiber links in existence today, owing to their low cost and ease of deployment. However, modal dispersion significantly limits the maximum data rates that they support. Recently, the ability to multiplex several streams of data through optical fibers has spawned the development of few-mode multimode fibers. These fibers possess the low-dispersion characteristics of single-mode fibers and the ability to multiplex several data streams using multiple-input multiple-output (MIMO) techniques and mode-specific filtering to increase data rates. While fibers with larger core diameters possess a larger number of spatial modes, they do not support data rates as high as few-mode fibers. In this paper, we describe a simulation based approach to characterize the tradeoffs between fiber diameter, achievable data rates and alignment tolerances of coherent links that employ graded-index multimode fibers (MMFs) of various dimensions, using the information theoretic outage capacity as the metric. The simulations used fibers' intermodal coupling characteristics to measure its multiplexing abilities and dispersion limitations with mode-specific filters and launch and detection spatial filter arrays. The simulations indicate that the bandwidth-length product achievable over few-mode fibers with MIMO techniques can exceed 250 Gb/s-km, while heavy mode spreading and limited mode selectivity limits the bandwidth-length product to under 25 Gb/s-km in fibers core diameters larger than 50 ?m. PMID:25090530

  13. Continuous, linearly intermixed fiber tows and composite molded article thereform

    NASA Technical Reports Server (NTRS)

    McMahon, Paul E. (Inventor); Chung, Tai-Shung (Inventor); Ying, Lincoln (Inventor)

    2000-01-01

    The instant invention involves a process used in preparing fibrous tows which may be formed into polymeric plastic composites. The process involves the steps of (a) forming a carbon fiber tow; (b) forming a thermoplastic polymeric fiber tow; (c) intermixing the two tows; and (d) withdrawing the intermixed tow for further use.

  14. Responses of microstructure optical fibers to strain and pressure

    NASA Astrophysics Data System (ADS)

    Jin, W.; Pang, M.

    2010-11-01

    The phase/birefringence sensitivities of the fundamental mode of air-silica microstructure optical fibers to strain and pressure are investigated. Theoretical models are built for both hollow-core photonic bandgap fibers and solid-core highly non-linear photonic crystal fibers to study the effects of axial strain, lateral pressure, and acoustic pressure on the fiber length and the effective refractive indexes of the fundamental mode. Numerical simulation shows that the phase/birefringence sensitivity to pressure of a hollow-core photonic bandgap fiber depends strongly on the thickness of the outer solid-silica layer and the air-filling ratio of the microstructure inner-cladding, and the normalized phase sensitivity to acoustic pressure can be 35 dB higher than that of the conventional single mode fiber. Potential applications of the microstructure optical fibers for high sensitivity hydrophones and novel polarization controllers are discussed.

  15. The association of fiber quality parameters and lint yield components of the F3 derived F4 progeny of two upland cotton populations 

    E-print Network

    Basal, Huseyin

    1996-01-01

    was positively correlated with fiber uniformity index, strength, LP, S/B, L/S, and L/SA, and negatively associated with length, F/S and F/SA. Fiber length was positively associated with fiber uniformity index, strength, SA/S, L/S, and negatively associated...

  16. Nucleation at macroscopic steps

    NASA Astrophysics Data System (ADS)

    Mederos, L.; Quintana, A.; Navascués, G.

    1984-11-01

    The classical heterogeneous nucleation theory is used to study nucleation at macroscopic steps. Line tension effects are included to give a correct description of the phenomena within the known limits of the theory. A criterion of preferential nucleation at steps (decoration criterion) is given. The expected behavior of the system for low macroscopic contact angles is found.

  17. Clustering of financial time series with application to index and enhanced index tracking portfolio

    Microsoft Academic Search

    Christian Dose; Silvano Cincotti

    2005-01-01

    A stochastic-optimization technique based on time series cluster analysis is described for index tracking and enhanced index tracking problems. Our methodology solves the problem in two steps, i.e., by first selecting a subset of stocks and then setting the weight of each stock as a result of an optimization process (asset allocation). Present formulation takes into account constraints on the

  18. STEP Experiment Requirements

    NASA Technical Reports Server (NTRS)

    Brumfield, M. L. (compiler)

    1984-01-01

    A plan to develop a space technology experiments platform (STEP) was examined. NASA Langley Research Center held a STEP Experiment Requirements Workshop on June 29 and 30 and July 1, 1983, at which experiment proposers were invited to present more detailed information on their experiment concept and requirements. A feasibility and preliminary definition study was conducted and the preliminary definition of STEP capabilities and experiment concepts and expected requirements for support services are presented. The preliminary definition of STEP capabilities based on detailed review of potential experiment requirements is investigated. Topics discussed include: Shuttle on-orbit dynamics; effects of the space environment on damping materials; erectable beam experiment; technology for development of very large solar array deployers; thermal energy management process experiment; photovoltaic concentrater pointing dynamics and plasma interactions; vibration isolation technology; flight tests of a synthetic aperture radar antenna with use of STEP.

  19. Tunable Fabry-Perot filter in cobalt doped fiber formed by optically heated fiber Bragg gratings pair

    NASA Astrophysics Data System (ADS)

    Li, Ying; Zhou, Bin; Zhang, Liang; He, Sailing

    2015-06-01

    In this paper, a tunable fiber Fabry-Perot (F-P) filter by all-optical heating is proposed. Two high reflective fiber Bragg gratings (FBG) fabricated in cobalt doped single mode fiber form the F-P cavity. The cobalt-doped fiber used here is an active fiber, and it transforms optical power from a control laser into heat effectively due to the nonradiative processes. The generated heat raises the refraction index of the fiber and enlarges the F-P cavity's length, realizing the all-optical tuning characteristics. By adjusting the power of the control laser, the resonant wavelength of our proposed fiber F-P filter can be high precisely controlled. The cavity length of the filter is carefully designed to make sure the longitude mode spacing is comparable to the grating bandwidth, making it single mode operating.

  20. Two-mode photonic crystal fibers

    Microsoft Academic Search

    Wei Jin; Zhi Wang; Jian Ju

    2005-01-01

    Index-guiding photonic crystal fibers with appropriate structural parameters support the fundamental and second order modes over a practically infinite wavelength range. The polarization principal axes and mode field patterns of the modes can be made stable by having different size air-holes along the orthogonal directions. The potential applications of such two-mode PCFs are discussed.

  1. Chalcogenide glass hollow core photonic crystal fibers

    Microsoft Academic Search

    Frédéric Désévédavy; Gilles Renversez; Johann Troles; Patrick Houizot; Laurent Brilland; Ion Vasilief; Quentin Coulombier; Nicholas Traynor; Frédéric Smektala; Jean-Luc Adam

    2010-01-01

    We report the first hollow core photonic crystal fibers (HC PCF) in chalcogenide glass. To design the required HC PCF profiles for such high index glass, we use both band diagram analysis to define the required photonic bandgap and numerical simulations of finite size HC PCFs to compute the guiding losses. The material losses have also been taken into account

  2. Fiber exposure reassessed with the new indices

    SciTech Connect

    Schneider, T.; Skotte, J. (Danish National Institute of Occupational Health, Copenhagen (Netherland))

    1990-02-01

    The concentration of airborne fibers longer than 5 microns, thinner than 3 microns, and with an aspect ratio exceeding 3 as counted by phase contrast optical microscopy is the most widely used fiber exposure index. Recently, more adequate, specific exposure indices for asbestosis, lung cancer, and mesothelioma risk have been suggested by Lippmann. The consequences of using these indices are examined on the basis of calculations for a broad range of theoretical and published size distributions. Optical microscopy appears to be a good predictor of the exposure indices for asbestosis and for lung cancer after scaling. Only fibers longer than about 3 microns need to be counted in a transmission electron microscope. The lung cancer index still cannot explain the large differences of risk among chrysotile exposures. Both the mesothelioma exposure index and the ratio mesothelioma to lung cancer index ranks in order of increasing risk: wollastonite, glass and mineral wool, amosite, glass microfibers, chrysotile, and crocidolite. Amosite is thus not ranked according to epidemiological evidence. Detailed size information should be made available so that the size criteria can be adjusted. It may still prove necessary to use fiber type specific concentration limits.

  3. Ribbon Fiber Laser-Theory and Experiment

    SciTech Connect

    Beach, R J; Feit, M D; Brasure, L D; Payne, S A

    2002-05-10

    A scalable fiber laser approach is described based on phase-locking multiple gain cores in an antiguided structure. The waveguide is comprised of periodic sequences of gain- and no-gain-loaded segments having uniform index, within the cladding region. Initial experimental results are presented.

  4. Improved retroreflection method for measuring the refractive index of liquids.

    PubMed

    Shao, Duo; Tian, Linghao; Chen, Jingfei; Chen, Xianfeng

    2010-06-01

    We propose a new method for measuring the refractive index of liquids with high precision; the method is based on use of the optical fiber end face. As an example, we investigated the refractive index of sugar solution under varying conditions tens of times. The results show that this method has the advantage of higher stability and repeatability. The concentration and the temperature-dependent refractive index of the sugar solution is also experimentally studied. PMID:20517374

  5. Gene-rich islands for fiber development in the cotton genome

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cotton fiber is an economically important seed trichome and the world's leading natural fiber used in the manufacture of textiles. As a step towards elucidating the genomic organization and distribution of gene networks responsible for cotton fiber development, we investigated the distribution of f...

  6. Manufacturing studies of fiber optic embedment in polymer-matrix composites

    Microsoft Academic Search

    A. Peter Jardine; John S. Madsen; Thomas M. Donnellan; Raymond J. Meilunas; A. G. Tobin

    1993-01-01

    Optical fibers were embedded into graphite-epoxy polymer matrix composites using a variety of geometries and insertion techniques to evaluate different manufacturing methods for embedding sensors in composite materials. Fiber durability during processing and post- processing handling was examined. In general, it was found that the fibers survived the processing step, even when efforts were made to induce failure. Handling during

  7. Production of fibrous activated carbons from natural cellulose (jute, coconut) fibers for water treatment applications

    Microsoft Academic Search

    Ngoc Hoa Phan; Sebastien Rio; Catherine Faur; Laurence Le Coq; Pierre Le Cloirec; Thanh Hong Nguyen

    2006-01-01

    Different fibrous activated carbons were prepared from natural precursors (jute and coconut fibers) by physical and chemical activation. Physical activation consisted of the thermal treatment of raw fibers at 950°C in an inert atmosphere followed by an activation step with CO2 at the same temperature. In chemical activation, the raw fibers were impregnated in a solution of phosphoric acid and

  8. Proposal and testing for a fiber-optic-based measurement of flow vorticity

    E-print Network

    Tong, Penger

    channel is an important first step for the development of a two-channel fiber-optic vorticity probe, whichProposal and testing for a fiber-optic-based measurement of flow vorticity Shenghong Yao, Penger Tong, and Bruce J. Ackerson A fiber-optic arrangement is devised to measure the velocity difference, v

  9. Multimaterial acoustic fibers

    E-print Network

    Chocat, Noémie

    2012-01-01

    The emergence of multimaterial fibers that combine a multiplicity of solid materials with disparate electrical, optical, and mechanical properties into a single fiber presents new opportunities for extending fiber applications ...

  10. A birefringence study of changes in myosin orientation during relaxation of skinned muscle fibers induced by photolytic ATP release.

    PubMed Central

    Peckham, M; Ferenczi, M A; Irving, M

    1994-01-01

    The birefringence of isolated skinned fibers from rabbit psoas muscle was measured continuously during relaxation from rigor produced by photolysis of caged ATP at sarcomere length 2.8-2.9 microns, ionic strength 0.1 M, 15 degrees C. Birefringence, the difference in refractive index between light components polarized parallel and perpendicular to the fiber axis, depends on the average degree of alignment of the myosin head domain with the fiber axis. After ATP release birefringence increased by 5.8 +/- 0.7% (mean +/- SE, n = 6) with two temporal components. A small fast component had an amplitude of 0.9 +/- 0.2% and rate constant of 63 s-1. By the completion of this component, the instantaneous stiffness had decreased to about half the rigor value, and the force response to a step stretch showed a rapid (approximately 1000 s-1) recovery phase. Subsequently a large slow birefringence component with rate constant 5.1 s-1 accompanied isometric force relaxation. Inorganic phosphate (10 mM) did not affect the fast birefringence component but accelerated the slow component and force relaxation. The fast birefringence component was probably caused by formation of myosin.ATP or myosin.ADP.Pi states that are weakly bound to actin. The average myosin head orientation at the end of this component is slightly more parallel to the fiber axis than in rigor. PMID:7811926

  11. Fiber optic sensor reliability issues in structural health monitoring

    NASA Astrophysics Data System (ADS)

    Xu, Zhihong; Bassam, Asadollah; Jia, Hongqiang; Tennant, Adam; Ansari, Farhad

    2005-05-01

    Reliability is an important aspect of any sensor, and especially in terms of long term monitoring of structures. Some issues pertaining to the reliability of optical fiber sensors in civil structures are discussed in this article. The strength and fatigue properties of optical fibers influence their performance, and life span. Lessons learnt from the reliability of optical fibers in the telecommunication industry are useful for assessment of reliability in optical fiber sensors. However, optical fiber sensors go through additional manufacturing steps, handling processes, and in general operate under environmental conditions and stress levels different from the telecommunication lines. In general, optical fiber sensors in structures are subjected to fatigue loading under high stresses. Other reliability concerns pertain to the effects of the packaging, installation issues at the construction site. These issues along with some of the results acquired from fatigue tests on fiber optic Bragg gratings and long gauge interferometric sensors are discussed in this article.

  12. Small-core chalcogenide microstructured fibers for the infrared

    SciTech Connect

    Desevedavy, Frederic; Renversez, Gilles; Brilland, Laurent; Houizot, Patrick; Troles, Johann; Coulombier, Quentin; Smektala, Frederic; Traynor, Nicholas; Adam, Jean-Luc

    2008-11-10

    We report several small-core chalcogenide microstructured fibers fabricated by the 'Stack and Draw' technique from Ge15Sb20S65 glass with regular profiles. Mode field diameters and losses have been measured at 1.55 {mu}m. For one of the presented fibers, the pitch is 2.5 {mu}m, three times smaller than that already obtained in our previous work, and the corresponding mode field diameter is now as small as 3.5 {mu}m. This fiber, obtained using a two step 'Stack and Draw' technique, is single-mode at 1.55 {mu}m from a practical point of view. We also report the first measurement of the attenuation between 1 and 3.5 {mu}m of a chalcogenide microstructured fiber. Experimental data concerning fiber attenuation and mode field diameter are compared with calculations. Finally, the origin of fiber attenuation and the nonlinearity of the fibers are discussed.

  13. Noise performance comparison of 1.5 microm correlated photon pair generation in different fibers.

    PubMed

    Zhou, Qiang; Zhang, Wei; Cheng, Jie-rong; Huang, Yi-dong; Peng, Jiang-de

    2010-08-01

    In this paper, the noise performances of 1.5 microm correlated photon pair generation based on spontaneous four wave-mixing in three types of fibers, i.e., dispersion shifted fiber, traditional highly nonlinear fiber and highly nonlinear microstructure fiber are investigated experimentally. Result of the comparison shows that highly nonlinear microstructure fiber has the lowest Raman noise photon generation rate among the three types of fibers while correlated photon pair generation rate is the same. Theoretical analysis indicates that the noise performance is determined by the nonlinear index and Raman response of the material in fiber core. The Raman response rises with increasing doping level, while, for the nonlinear index, the impact of doping level is weak. As a result, highly nonlinear microstructure fiber with pure silica core has the best noise performance and great potential in practical sources of correlated photon pairs and heralded single photons. PMID:20721100

  14. Fiber-optic humidity sensor based on an air-gap long period fiber grating

    NASA Astrophysics Data System (ADS)

    Fu, Ming-Yue; Lin, Guei-Ru; Liu, Wen-Fung; Wu, ChengWen

    2011-01-01

    In this paper, we propose a novel high-sensitivity fiber-optic humidity sensor based on a calcium chloride thin film to be coated on an air-gap long-period grating fabricated (AG-LPG) by combining the fiber side-polishing and fiber etching methods. When the surrounding refractive index of the air-gap long-period grating is changed by a change in humidity, the grating resonant wavelength is considered varied. Experimental results indicate that humidity can be detected by this sensing mechanism and has a high sensitivity of about 1.36 nm/1%RH.

  15. Fiber distributed feedback laser

    NASA Technical Reports Server (NTRS)

    Elachi, C.; Evans, G. A.; Yeh, C. (inventors)

    1976-01-01

    Utilizing round optical fibers as communication channels in optical communication networks presents the problem of obtaining a high efficiency coupling between the optical fiber and the laser. A laser is made an integral part of the optical fiber channel by either diffusing active material into the optical fiber or surrounding the optical fiber with the active material. Oscillation within the active medium to produce lasing action is established by grating the optical fiber so that distributed feedback occurs.

  16. Designing the Structure of Carbon Fibers for Optimal Mechanical Properties

    SciTech Connect

    Ozcan, Soydan [ORNL; Vautard, Frederic [ORNL; Naskar, Amit K [ORNL

    2014-01-01

    Carbon fiber manufacturing follows generic processing steps: formation of thermoplastic fibers, stabilization, and carbonization. The final structures and end properties of the carbon fiber can differ significantly depending on the precursor chemistry and the associated processing sciences. Polyacrylonitrile (PAN) and mesophase pitch are the predominant precursors used in the production of carbon fibers. PAN-based carbon fibers consist of nanocrystalline graphitic domains typically 1.5 5 nm in size surrounded by amorphous carbon; in contrast, pitch-based carbon fibers are 10 50 nm crystallites with the graphitic (002) planes mostly aligned parallel to the fiber axis. It has been seen that the skin core structure of PAN-based carbon fibers plays a significant role in their mechanical properties. Designing a more homogenous carbon fiber microstructure by controlling the starting polymer and process parameters results in a different set of tensile strengths and elastic moduli. In this study the microstructural defect distribution (0.1 200 nm), measured by small-angle X-ray scattering, was shown to be directly related to the tensile strength of the carbon fibers. Here the formation of carbon structures from various polymer precursors is reviewed. Such a comprehensive understanding offers the opportunity to design carbon fiber microstructures with improved properties and to ultimately create new types of carbon fibers from alternative precursors at reduced cost.

  17. Modal analysis of optical fibers with symmetrically distributed nonuniform cores

    Microsoft Academic Search

    Naoto Kishi; K. Tayama; E. Yamashita

    1996-01-01

    This paper describes the modal analysis of optical fibers with symmetrically distributed multiple cores. Each core has an identical, axially symmetrical, and nonuniform refractive index profile. Group theoretical approach is applied to treat the symmetry of the waveguide structure. The point-matching method combined with the staircase-approximation method is used to take into account complex boundary conditions and complex refractive index

  18. Name: Department: GID #: Index #

    E-print Network

    Maxwell, Bruce D.

    Name: Department: GID #: Index #: (Current Index used to pay salary) In order to participate % of salary from my grant fund(s): % Index #: Beginning (mo./yr.): % Index #: Ending (mo./yr.): % Index #: % Index #: Total % (must have a minimum of 10% FTE to participate in the program) Do you have sufficient

  19. The Numerical Analysis of Soliton Propagation with Plit-Step Fourier Transform Method

    Microsoft Academic Search

    Z B Wang; H Y Yang; Z Q Li

    2006-01-01

    It is very important for practicability and system designing to study on the optical soliton transform and evolution with numerical simulation. In this paper, the split-step Fourier transform method (SSFM) is particularly introduced and the simulation is also given. The Matlab language is used to simulate the soliton propagation in the optical fiber. The influence of optical fiber waste is

  20. All propagation modes of large-core multimode optical fibers with an arbitrary core profile

    Microsoft Academic Search

    Masashi Eguchi; Suguru Horinouchi

    2004-01-01

    Plastic optical fibers are typical large-core multimode optical fibers. High-bandwidth graded-index plastic optical fibers, which support a great number of propagation modes compared with conventional silica-glass multimode optical fibers, were developed in the 1990s. However, because they support a great number of propagation modes, their modal analyses have been limited to the WKB analysis. We obtain all the propagation modes

  1. Sensing Features of Long Period Gratings in Hollow Core Fibers

    PubMed Central

    Iadicicco, Agostino; Campopiano, Stefania

    2015-01-01

    We report on the investigation of the sensing features of the Long-Period fiber Gratings (LPGs) fabricated in hollow core photonic crystal fibers (HC-PCFs) by the pressure assisted Electric Arc Discharge (EAD) technique. In particular, the characterization of the LPG in terms of shift in resonant wavelengths and changes in attenuation band depth to the environmental parameters: strain, temperature, curvature, refractive index and pressure is presented. The achieved results show that LPGs in HC-PCFs represent a novel high performance sensing platform for measurements of different physical parameters including strain, temperature and, especially, for measurements of environmental pressure. The pressure sensitivity enhancement is about four times greater if we compare LPGs in HC and standard fibers. Moreover, differently from LPGs in standard fibers, these LPGs realized in innovative fibers, i.e., the HC-PCFs, are not sensitive to surrounding refractive index. PMID:25855037

  2. Sensing features of long period gratings in hollow core fibers.

    PubMed

    Iadicicco, Agostino; Campopiano, Stefania

    2015-01-01

    We report on the investigation of the sensing features of the Long-Period fiber Gratings (LPGs) fabricated in hollow core photonic crystal fibers (HC-PCFs) by the pressure assisted Electric Arc Discharge (EAD) technique. In particular, the characterization of the LPG in terms of shift in resonant wavelengths and changes in attenuation band depth to the environmental parameters: strain, temperature, curvature, refractive index and pressure is presented. The achieved results show that LPGs in HC-PCFs represent a novel high performance sensing platform for measurements of different physical parameters including strain, temperature and, especially, for measurements of environmental pressure. The pressure sensitivity enhancement is about four times greater if we compare LPGs in HC and standard fibers. Moreover, differently from LPGs in standard fibers, these LPGs realized in innovative fibers, i.e., the HC-PCFs, are not sensitive to surrounding refractive index. PMID:25855037

  3. Chemical Sensing Using Fiber Cavity Ring-Down Spectroscopy

    PubMed Central

    Waechter, Helen; Litman, Jessica; Cheung, Adrienne H.; Barnes, Jack A.; Loock, Hans-Peter

    2010-01-01

    Waveguide-based cavity ring-down spectroscopy (CRD) can be used for quantitative measurements of chemical concentrations in small amounts of liquid, in gases or in films. The change in ring-down time can be correlated to analyte concentration when using fiber optic sensing elements that change their attenuation in dependence of either sample absorption or refractive index. Two types of fiber cavities, i.e., fiber loops and fiber strands containing reflective elements, are distinguished. Both types of cavities were coupled to a variety of chemical sensor elements, which are discussed and compared. PMID:22294895

  4. Rapid fabrication of microhole array structured optical fibers.

    PubMed

    Yang, Rui; Yu, Yong-Sen; Chen, Chao; Chen, Qi-Dai; Sun, Hong-Bo

    2011-10-01

    A microhole array in a common single-mode fiber is fabricated by selective chemical etching of femtosecond-laser-induced fiber Bragg grating (FBG), which has a laser-modified region extending from the fiber core to the cladding-air boundary due to laser self-focusing. The shape and size of the orderly microhole on the fiber surface are controlled via changing conditions of FBG fabrication and chemical etching. A simultaneous sensing for surrounding refractive index and temperature is demonstrated by this microhole array FBG through measurement of the transmission power change and Bragg resonant wavelength shift. PMID:21964128

  5. FOA Lecture 22: Mode Power Distribution in Multimode Fibers

    NSDL National Science Digital Library

    This is Lecture 22 in the Fiber Optics Association's lecture series on multimode fibers. In this lecture, the presenter briefly reviews modes in graded-index multimode fibers then shows how you can actually see the modes by using visible laser light from a VFL (visual fault locator.) The presenter will also show the effect of a mandrel wrap on the fiber, allowing you to actually see how the higher order modes are removed by the mandrel wrap. Running time for the lecture is 8:29. Flash is required to view the video.

  6. Modeling of transient modal instability in fiber amplifiers.

    PubMed

    Ward, Benjamin G

    2013-05-20

    A model of transient modal instability in fiber amplifiers is presented. This model combines an optical beam propagation method that incorporates laser gain through local solution of the rate equations and refractive index perturbations caused by the thermo-optic effect with a time-dependent thermal solver with a quantum defect heating source term. This model predicts modal instability a fiber amplifier operating at 241, 270, and 287 Watts of output power characterized by power coupling to un-seeded modes, the presence of stable and unstable regions within the fiber, and rapid intensity variations along the fiber. The instability becomes more severe as the power is increased. PMID:23736426

  7. Over an octave cascaded Raman scattering in short highly germanium-doped silica fiber.

    PubMed

    Yin, Ke; Zhang, Bin; Yang, Weiqiang; Chen, Hongwei; Hou, Jing

    2013-07-01

    In this paper, we report on cascaded Raman scattering (RS) in a highly germanium-doped silica fiber (HGDF) pumped by a picosecond pulsed master oscillator power amplifier (MOPA) system at 1064 nm in the normal dispersion regime. Benefited by the higher Raman gain of germanium (GeO2) than silica in the core, the length of the HGDF is only several meters. The broadest output spectrum comprises of 10 orders Raman stokes waves and eventually evolves into a supercontinuum (SC) spanning from 1000 to beyond 2100 nm with an output average power up to Watt scale. To the best of our knowledge, this is the first time to obtain such a broad cascaded RS spectrum in a short length of GeO2-doped step index silica fiber. We also numerically investigate the propagation of picosecond pulses in this HGDF based on the generalized nonlinear Schrödinger equation (GNLSE) which includes most of the dispersive and nonlinear effects, and the simulation results are in fairly good agreement with our experiments. It is believed that the numerical approach adopted in this paper is very beneficial for designing customized cascaded Raman fiber lasers before experimental implementations. PMID:23842385

  8. Supercontinuum Generation in Photonic Crystal Fibers Possessing High Birefringence and Large Optical Nonlinearity

    E-print Network

    Sharma, Mohit; Konar, S

    2015-01-01

    This paper presents the design of an index guided highly birefringent photonic crystal fiber which promises to yield very large birefringence ~3.33 X 10^(-2) at 1550 nm and ~1.75 X 10^(-2) at 1064 nm as well as large effective nonlinearity ~80 W^(-1)km^(-1). Optical supercontinuum generation in the proposed fiber using a 1064 nm pump source with peak power of 1kW has been also presented. Finite difference time domain method (FDTD) has been employed to examine the optical properties such as fiber birefringence, mode field, V-parameter, walk-off and optical nonlinearity, while the Split-step Fourier method is used to solve the nonlinear Schrodinger equation felicitating the study of supercontinuum generation. Simulation results indicate that horizontal input pulse yields superior continuum in comparison to that of the vertically polarized input. However, the broadening of the continuum is about 1450 nm in case of horizontally polarized input light whereas it is approximately 2350 nm for vertically polarized.

  9. Does topology drive fiber polymerization?

    PubMed

    Huang, Lihong; Hsiao, Joe Ping-Lin; Powierza, Camilla; Taylor, Russell M; Lord, Susan T

    2014-12-16

    We have developed new procedures to examine the early steps in fibrin polymerization. First, we isolated fibrinogen monomers from plasma fibrinogen by gel filtration. Polymerization of fibrinogen monomers differed from that of plasma fibrinogen. The formation of protofibrils was slower and the transformation of protofibrils to fibers faster for the fibrinogen monomers. Second, we used formaldehyde to terminate the polymerization reactions. The formaldehyde-fixed products obtained at each time point were examined by dynamic light scattering and transmission electron microscopy (TEM). The data showed the formaldehyde-fixed products were stable and representative of the reaction intermediates. TEM images showed monomers, short oligomers, protofibrils, and thin fibers. The amount and length of these species varied with time. Short oligomers were less than 5% of the molecules at all times. Third, we developed models that recapitulate the TEM images. Fibrin monomer models were assembled into protofibrils, and protofibrils were assembled into two-strand fibers using Chimera software. Monomers were based on fibrinogen crystal structures, and the end-to-end interactions between monomers were based on D-dimer crystal structures. Protofibrils assembled from S-shaped monomers through asymmetric D:D interactions were ordered helical structures. Fibers were modeled by duplicating a protofibril and rotating the duplicate 120° around its long axis. No specific interactions were presumed. The two protofibrils simply twisted around one another to form a fiber. This model suggests that the conformation of the protofibril per se promotes the assembly into fibers. These findings introduce a novel mechanism for fibrin assembly that may be relevant to other biopolymers. PMID:25419972

  10. Model of an axially strained weakly guiding optical fiber modal pattern

    NASA Technical Reports Server (NTRS)

    Egalon, Claudio O.; Rogowski, Robert S.

    1992-01-01

    Axial strain can be determined by monitoring the modal pattern variation of an optical fiber. The results of a numerical model developed to calculate the modal pattern variation at the end of a weakly guiding optical fiber under axial strain is presented. Whenever an optical fiber is under stress, the optical path length, the index of refraction, and the propagation constants of each fiber mode change. In consequence, the modal phase term for the fields and the fiber output pattern are also modified. For multimode fibers, very complicated patterns result. The predicted patterns are presented, and an expression for the phase variation with strain is derived.

  11. Generation of Cerenkov radiation at 850 nm in higher-order-mode fiber

    PubMed Central

    Cheng, Ji; Lee, Jennifer H.; Wang, Ke; Xu, Chris; Jespersen, Kim G.; Garmund, Martin; Grüner-Nielsen, Lars; Jakobsen, Dan

    2011-01-01

    We demonstrate generation of Cerenkov radiation at 850 nm in a higher-order-mode (HOM) fiber. The LP02 mode in this solid, silica-based fiber has anomalous dispersion from 690 nm to 810 nm. Cerenkov radiation with 3 nJ pulse energy is generated in this module, exhibiting 60% energy conversion efficiency from the input. The HOM fiber provides a valuable fiber platform for nonlinear wavelength conversion with pulse energies in-between index-guided silica-core photonic crystal fibers and air-core photonic bandgap fibers. PMID:21643129

  12. Placing Fiber Optic Cables in Multioccupied Ducts

    Microsoft Academic Search

    P. Grimado; A. Colucci

    1986-01-01

    Placing fiber optic cable (FOC) in duct containing copper cable can save millions of construction dollars. This paper describes techniques used successfully in rodding duct over copper cables in actual field installations-a necessary and most critical step preparatory to the actual placement of the FOC. In addition, a mathematical model useful in planning and predicting expected FOC pulling tensions for

  13. Stepping Motor Control System

    E-print Network

    Larson, Noble G.

    This paper describes a hardware system designed to facilitate position and velocity control of a group of eight stepping motors using a PDP-11. The system includes motor driver cards and other interface cards in addition ...

  14. Detailed numerical investigation of the interaction of longitudinal acoustic waves with fiber Bragg gratings in suspended-core fibers

    NASA Astrophysics Data System (ADS)

    Silva, Ricardo E.; Hartung, Alexander; Rothhardt, Manfred; Pohl, Alexandre A. P.; Bartelt, Hartmut

    2015-06-01

    The interaction between longitudinal acoustic waves and fiber Bragg gratings in suspended-core optical fibers is numerically investigated. The fiber core size and the air hole size are varied, and the mechanical and grating properties are simulated by means of the finite element method and the transfer matrix method, respectively. Changes of the effective index, confinement factor, silica area, strain and wavelength shift induced by the acoustic wave are evaluated, and the resultant side lobe reflectivity is estimated. A side lobe reflectivity increase of 66% compared to standard fibers is estimated, which allows reducing the modulation index or the grating length in as much as 75%. Besides, the larger reduction of the required acoustic power for achieving the acousto-optic modulation points out to more efficient modulator devices in suspended-core fibers.

  15. Simultaneous measurement of temperature and strain by combining a fiber Bragg grating and the pigtail fiber covered with epoxy resin.

    PubMed

    Wu, Xiaowei; Xue, Hongchao; Meng, Hongyun; Shen, Wei; Wang, Wei; Tan, Chunhua; Huang, Xuguang

    2011-06-01

    A fiber sensor for simultaneous measurement of temperature and strain based on a fiber Bragg grating (FBG) with the pigtail fiber covered with epoxy resin is presented. The side mode suppression ratio of the FBG will vary with the temperature due to the Fresnel reflection from the interface between the pigtail fiber and the epoxy resin whose refractive index is sensitive to the temperature. The sensor is also capable of simultaneous measurement temperature and strain by combining the Bragg wavelength shift characteristics as the temperature and strain of the FBG. PMID:21721721

  16. Viscoelasticity of stepped interfaces

    NASA Astrophysics Data System (ADS)

    Skirlo, S. A.; Demkowicz, M. J.

    2013-10-01

    Using molecular dynamics modeling, we show that interfaces in sputter deposited Cu-Nb superlattices exhibit time-dependent elasticity, i.e., viscoelasticity, under shear loading. In the high temperature and small strain rate limit, the interfacial shear modulus approaches a value proportional to the density of steps in the interface. It may therefore be possible to tailor the low-frequency shear moduli of interfaces by controlling their step densities.

  17. Nanofibers from Melt Blown Fiber-in-Fiber Polymer Blends

    NASA Astrophysics Data System (ADS)

    Wang, Zaifei; Zuo, Feng; Tan, Dawud; Jeung, Soondeuk; Macosko, Christopher; Bates, Frank; Cummins Filtration Collaboration; Department of Chemical Engineering and Materials Science, University of Minnesota Twin Cities Team

    2014-03-01

    Nanofibers were generated by melt blowing three sets of polymer blends each comprised of pairs of immiscible components. Blends containing minority phases of poly(ethylene-co-chlorotrifluoroethylene) (PECTFE) in poly(butylene terephthalate) (PBT), PECTFE in poly(styrene) (PS), and PBT in PS, were melt blown into long (>100 microns) fibers with average diameters of several microns. Electron microscope revealed that melt blowing transformed the initial spherical dispersions into a nanofibers-in-fiber morphology. Macroscopic mats of nonwoven PBT and PECTFE nanofibers, with average diameters as small as 70 nm, were isolated by selectively removing the majority phase with a solvent. This method provides a potentially inexpensive, high throughput, one step route to scalable quantities of polymeric nanofibers. Cummins Filtration

  18. Design of large mode area, mode selection fiber

    NASA Astrophysics Data System (ADS)

    Jin, Liang; Xu, Li; Zhang, He; Zou, Yonggang; Ding, Ye; Ma, Xiaohui

    2014-12-01

    The paper study on the effect of index distribution on the mode field and calculated the mode distribution in various index profiles. A single mode gaussian hybrid multicore fiber with 19 hexagonally arranged high index quartz rods is designed and investigated. Theoretical and simulative results are presented and compared to the conventional large mode area double clad fiber, the fundamental mode (FM) area can be reached 694.28 ?m2, the confinement loss of FM and high order modes (HOMs) are 0.186 dB/m and 1.48 dB/m respectively with the bending radius of 20 cm at 1.064 ?m wavelength, moreover, the index distribution can resistant the mode field distortion, which caused by fiber bending. So the FM delivery can be formed and the beam quality can be improved.

  19. Biorefining of wood: combined production of ethanol and xylanase from waste fiber sludge

    Microsoft Academic Search

    Adnan Cavka; Björn Alriksson; Shaunita H. Rose; Willem H. van Zyl; Leif J. Jönsson

    The possibility to utilize fiber sludge, waste fibers from pulp mills and lignocellulose-based biorefineries, for combined\\u000a production of liquid biofuel and biocatalysts was investigated. Without pretreatment, fiber sludge was hydrolyzed enzymatically\\u000a to monosaccharides, mainly glucose and xylose. In the first of two sequential fermentation steps, the fiber sludge hydrolysate\\u000a was fermented to cellulosic ethanol with the yeast Saccharomyces cerevisiae. Although

  20. Experimental and Numerical Investigation of Single Frequency Amplifier with Photonic Bandgap Fiber at 1178 nm

    NASA Astrophysics Data System (ADS)

    Wang, Jian-Hua; Cui, Shu-Zhen; Hu, Jin-Meng; Cao, Fen; Fang, Yong; Lu, Hui-Ling

    2014-06-01

    A single frequency photonic bandgap fiber amplifier at 1178 nm is investigated experimentally and numerically. With a pump power of 81 W, a single frequency 1178 nm fiber laser of 10.3 W is obtained with a 3W seed laser and a 20 m gain fiber. Numerical simulation is conducted with a rate equation model taking amplified spontaneous emission and stimulated Brillouin scattering (SBS) into consideration. Temperature distribution along the fiber is applied for SBS suppression, more than 50 W single frequency fiber laser at 1178 nm is predicted theoretically with a 5W seed laser and a 40 m long gain fiber with five temperature steps.

  1. Fiber Optics Introduction

    E-print Network

    La Rosa, Andres H.

    .pdf · http://www.sff.net/people/Jeff.Hecht/history.htm · http://www.timbercon.com/History-of-Fiber-OpticsFiber Optics #12;Introduction · History of Fiber Optics · Types and Structure of Fibers · Loss Mechanisms and Applications · Linearly Polarized Mode Solutions #12;History · 1790's- Optical telegraph

  2. Infrared fiber optics

    Microsoft Academic Search

    J. A. Harrington; R. Turk; M. Henderson; J. Myer

    1979-01-01

    This interim technical report summarizes the first year's research efforts to fabricate optical communications fibers that are transmissive between 1 and 12 micrometers. The ultimate objective of this program is to prepare infrared transmitting fibers with losses less than 5 dB\\/km. In preparing infrared transparent fibers with these losses, we are emphasizing the extrusion into fiber of very pure KCl

  3. Eliptically polarizing optical fiber

    Microsoft Academic Search

    Ian M. Bassett; Margareta Bjarme; Daryl Chan; Ian G. Clarke; Justin Digweed; Tom Ryan; Andrew Michie; Danny W. Wong

    1999-01-01

    Elliptically polarizing optical fiber has been fabricated. Measurements show an extinction of the lossy mode relative to the transmitted mode of around 10 dB\\/m. The preform is spun during drawing and the ellipticity of the transmitted polarization state is as expected from the measured beat length of the unspun fiber and the pitch length of the spun fiber. This fiber

  4. Microstructured Polymer Optical Fibers

    Microsoft Academic Search

    Alexander Argyros

    2009-01-01

    The fabrication, materials, properties and applications of microstructured polymer optical fibers are reviewed. Microstructured polymer optical fibers formed the basis of extensive work on the physics of microstructured fibers, and an outline of the contribution to the wider field of microstructured fibers is also presented.

  5. Structural diagnostics using optical fiber sensors

    NASA Astrophysics Data System (ADS)

    Surace, Giuseppe; Chiaradia, Agostino

    1997-11-01

    After establishing the basis for assessing the structural implications of introducing a widespread sensor architecture in laminated composite materials in order to precisely identify and locate damage, the paper addresses the problem of structural diagnostics with a discussion of the development of several optical sensors. The research project will first investigate a passive optical fiber impact sensor to be implemented in the matrix of a composite material used in aeronautic and automotive applications. The senor's operating principle is based on the changes in propagation conditions occurring in a fiber subjected to transverse compression: under these circumstances, structural microdistortions produce local energy losses and hence a reduction in the optical power which propagates in the fiber and can be measured at its opposite end. As optical power losses also take place as a result of micro-bending of the optical fiber's longitudinal axis, a preliminary feasibility study will measure power attenuation versus fiber curve radius as the first step in the development of an optical fiber delamination sensor which locates separations between the layers of a composite material, i.e. debonding of sandwich panel core faces. Finally, an active impact sensor will be developed which uses optical fiber's sensitivity to pressure changes to detect the pressure gradient caused by an approaching vehicle or obstacle. The automotive industry will be able to make strategic use of these sensors, for example by installing them on vehicle sides to active the side airbag in the event of impact or collision.

  6. Advanced specialty fiber designs for fiber lasers

    NASA Astrophysics Data System (ADS)

    Dong, Liang; McKay, Hugh A.; Thomas, B. K.; Fu, Libin; Suzuki, Shigeru; Ohta, Michiharu; Marcinkeivicius, Andrius

    2011-02-01

    Progress in advanced specialty fibers is the foundation to further breakthroughs in fiber lasers. Recently, we have been working to advance several areas of developments in specialty fibers and would like to review these efforts here. The first topic is in the further development of all-glass large core leakage channel fibers (LCF) for robust and practical solutions for power scaling. The second area is the development of wide band air-core fibers with an innovative square lattice cladding and the demonstration of a factor of two improvements in bandgap over conventional hexagonal lattice. These air-core fibers are critical for fiber delivery solution of both CW and pulsed fiber lasers in the future. The last topic is a new development in design and simulation of SBS gains in optical fibers by incorporating leaky acoustic modes. These leaky acoustic modes have been mostly overlooked so far. It is essential that they are considered in SBS simulations in fibers, because they are normal solutions to the acoustic waveguide equations and have similar loss to guided acoustic modes where the acoustic mode loss is dominated by material loss. This leads to much improved resolution of SBS gain spectrum in fibers and to new design insights to the limit of SBS suppression based on anti-guide acoustic waveguide designs.

  7. Recent advances in the design of photonic bandgap and hybrid fibers: from LMA to HNL fibers

    NASA Astrophysics Data System (ADS)

    Quiquempois, Yves; Baz, Assaad; Vanvincq, Olivier; Valentin, Constance; Bigot, Laurent; Bouwmans, Géraud; Kudlinski, Alexandre; Mussot, Arnaud; Calvet, Pierre; Hugonnot, Emmanuel; Douay, Marc

    2012-10-01

    Solid-Core Photonic BandGap Fibers (SC-PBGF) belongs to the family of microstructured optical fibers whereby the cladding is made of high refractive index inclusions as compared to that of the fiber core. In such fibers, light is confined to the core by an anti-resonant mechanism and several high transmission windows separated by high loss regions compose the transmission spectrum. Guiding mechanism is then identical to the one observed in Hollow-Core PBGF (HC-PBGF) except that a solid core can be exploited. Such PBGFs have proven to be good candidates for single-mode high power delivery and for controlling the spectral extension of supercontinuum generation. Mixing different types of resonators in the cladding or mixing PBG with modifed-Total Internal Reection (m-TIR) mechanism also lead to original and more exible fiber designs. Recent developments in the design and realization of Large Mode Area (LMA) and Highly NonLinear (HNL) fibers are presented, including single-mode ring-structured Bragg _bers, LMA fibers exhibiting a fundamental mode with a flat-top profile, and hybrid fibers for supercontinuum generation or frequency conversion.

  8. Fiber optic connector

    DOEpatents

    Rajic, Slobodan (Knoxville, TN); Muhs, Jeffrey D. (Lenior City, TN)

    1996-01-01

    A fiber optic connector and method for connecting composite materials within which optical fibers are imbedded. The fiber optic connector includes a capillary tube for receiving optical fibers at opposing ends. The method involves inserting a first optical fiber into the capillary tube and imbedding the unit in the end of a softened composite material. The capillary tube is injected with a coupling medium which subsequently solidifies. The composite material is machined to a desired configuration. An external optical fiber is then inserted into the capillary tube after fluidizing the coupling medium, whereby the optical fibers are coupled.

  9. Fiber optic temperature sensor

    NASA Technical Reports Server (NTRS)

    Sawatari, Takeo (Inventor); Gaubis, Philip A. (Inventor); Mattes, Brenton L. (Inventor); Charnetski, Clark J. (Inventor)

    1999-01-01

    A fiber optic temperature sensor uses a light source which transmits light through an optical fiber to a sensor head at the opposite end of the optical fiber from the light source. The sensor head has a housing coupled to the end of the optical fiber. A metallic reflective surface is coupled to the housing adjacent the end of the optical fiber to form a gap having a predetermined length between the reflective surface and the optical fiber. A detection system is also coupled to the optical fiber which determines the temperature at the sensor head from an interference pattern of light which is reflected from the reflective surface.

  10. Fiber optic temperature sensor

    NASA Technical Reports Server (NTRS)

    Sawatari, Takeo (Inventor); Gaubis, Philip A. (Inventor)

    2000-01-01

    A fiber optic temperature sensor uses a light source which transmits light through an optical fiber to a sensor head at the opposite end of the optical fiber from the light source. The sensor head has a housing coupled to the end of the optical fiber. A metallic reflective surface is coupled to the housing adjacent the end of the optical fiber to form a gap having a predetermined length between the reflective surface and the optical fiber. A detection system is also coupled to the optical fiber which determines the temperature at the sensor head from an interference pattern of light which is reflected from the reflective surface.

  11. Computing discharge using the index velocity method

    USGS Publications Warehouse

    Levesque, Victor A.; Oberg, Kevin A.

    2012-01-01

    Application of the index velocity method for computing continuous records of discharge has become increasingly common, especially since the introduction of low-cost acoustic Doppler velocity meters (ADVMs) in 1997. Presently (2011), the index velocity method is being used to compute discharge records for approximately 470 gaging stations operated and maintained by the U.S. Geological Survey. The purpose of this report is to document and describe techniques for computing discharge records using the index velocity method. Computing discharge using the index velocity method differs from the traditional stage-discharge method by separating velocity and area into two ratings—the index velocity rating and the stage-area rating. The outputs from each of these ratings, mean channel velocity (V) and cross-sectional area (A), are then multiplied together to compute a discharge. For the index velocity method, V is a function of such parameters as streamwise velocity, stage, cross-stream velocity, and velocity head, and A is a function of stage and cross-section shape. The index velocity method can be used at locations where stage-discharge methods are used, but it is especially appropriate when more than one specific discharge can be measured for a specific stage. After the ADVM is selected, installed, and configured, the stage-area rating and the index velocity rating must be developed. A standard cross section is identified and surveyed in order to develop the stage-area rating. The standard cross section should be surveyed every year for the first 3 years of operation and thereafter at a lesser frequency, depending on the susceptibility of the cross section to change. Periodic measurements of discharge are used to calibrate and validate the index rating for the range of conditions experienced at the gaging station. Data from discharge measurements, ADVMs, and stage sensors are compiled for index-rating analysis. Index ratings are developed by means of regression techniques in which the mean cross-sectional velocity for the standard section is related to the measured index velocity. Most ratings are simple-linear regressions, but more complex ratings may be necessary in some cases. Once the rating is established, validation measurements should be made periodically. Over time, validation measurements may provide additional definition to the rating or result in the creation of a new rating. The computation of discharge is the last step in the index velocity method, and in some ways it is the most straight-forward step. This step differs little from the steps used to compute discharge records for stage-discharge gaging stations. The ratings are entered into database software used for records computation, and continuous records of discharge are computed.

  12. Miniature temperature sensor with germania-core optical fiber.

    PubMed

    Yang, Jingyi; Zheng, Yangzi; Chen, Li Han; Chan, Chi Chiu; Dong, Xinyong; Shum, Perry Ping; Su, Haibin

    2015-07-13

    A miniature all-fiber temperature sensor is demonstrated by using a Michelson interferometer formed with a short length of Germania-core, silica-cladding optical fiber (Ge-fiber) fusion-spliced to a conventional single-mode fiber (SMF). Thanks to the large differential refractive index of the Ge-fiber sensing element, a reasonably small free spectral range (FSR) of 18.6 nm is achieved even with an as short as 0.9 mm Ge-fiber that may help us increase the measurement accuracy especially in point sensing applications and, at the same time, keep large measurement temperature range without overlapping reading problem. Experimental results show that high sensitivity of 89.0 pm/°C is achieved and the highest measurement temperature is up to 500°C. PMID:26191830

  13. DIDA: Distributed Indexing Dispatched Alignment.

    PubMed

    Mohamadi, Hamid; Vandervalk, Benjamin P; Raymond, Anthony; Jackman, Shaun D; Chu, Justin; Breshears, Clay P; Birol, Inanc

    2015-01-01

    One essential application in bioinformatics that is affected by the high-throughput sequencing data deluge is the sequence alignment problem, where nucleotide or amino acid sequences are queried against targets to find regions of close similarity. When queries are too many and/or targets are too large, the alignment process becomes computationally challenging. This is usually addressed by preprocessing techniques, where the queries and/or targets are indexed for easy access while searching for matches. When the target is static, such as in an established reference genome, the cost of indexing is amortized by reusing the generated index. However, when the targets are non-static, such as contigs in the intermediate steps of a de novo assembly process, a new index must be computed for each run. To address such scalability problems, we present DIDA, a novel framework that distributes the indexing and alignment tasks into smaller subtasks over a cluster of compute nodes. It provides a workflow beyond the common practice of embarrassingly parallel implementations. DIDA is a cost-effective, scalable and modular framework for the sequence alignment problem in terms of memory usage and runtime. It can be employed in large-scale alignments to draft genomes and intermediate stages of de novo assembly runs. The DIDA source code, sample files and user manual are available through http://www.bcgsc.ca/platform/bioinfo/software/dida. The software is released under the British Columbia Cancer Agency License (BCCA), and is free for academic use. PMID:25923767

  14. Fiber optic monitoring device

    DOEpatents

    Samborsky, James K. (605 Groves Blvd., N. Augusta, SC 29841)

    1993-01-01

    A device for the purpose of monitoring light transmissions in optical fibers comprises a fiber optic tap that optically diverts a fraction of a transmitted optical signal without disrupting the integrity of the signal. The diverted signal is carried, preferably by the fiber optic tap, to a lens or lens system that disperses the light over a solid angle that facilitates viewing. The dispersed light indicates whether or not the monitored optical fiber or system of optical fibers is currently transmitting optical information.

  15. development index (HDI)

    E-print Network

    HDI rank a Human development index (HDI) value Life expectancy at birth (years) Adult literacy rate per capita (PPP US$) Life expectancy index Education index GDP index GDP per capita (PPP US$) rank development index (HDI) value Life expectancy at birth (years) Adult literacy rate (% aged 15 and above) Com

  16. Toughness of fiber reinforced shotcrete

    SciTech Connect

    Morgan, D.R. [AGRA Earth and Environmental Ltd., Burnaby, British Columbia (Canada); Chen, L. [Univ. of British Columbia, Vancouver, British Columbia (Canada); Beaupre, D. [Univ. Laval, Quebec City, Quebec (Canada)

    1995-12-31

    Fibers are added to shotcrete to improve energy absorption and impact resistance, to provide crack resistance and crack control, and to provide apparent ductility, i.e., an ability to continue to carry load after the shotcrete matrix has cracked. In order to be able to quantify the benefits of fiber addition, a variety of different toughness measuring systems have been developed in different countries. Most commonly used are flexural toughness systems which determine load vs. deflection responses and relate the area under the curve to some absolute or dimensionless index energy parameter. In North America the ASTM C1018 test method is most commonly used. In Japan the JSCE-SF4 test procedure is used. A variety of procedures have been used in Europe, but the template approach of the Norwegian Guidelines NBP No. 7, seems to be finding favor. This paper briefly assesses the relative advantages and disadvantages of the various methods of characterizing toughness. It then provides recommendations for a new procedure which uses the ASTM C1018 test method for generating the flexural load vs. deflection curve, but analyzes the data using a modified version of the Norwegian template approach. The load vs. deflection curve is directly compared against four residual strength curves and the fiber reinforced shotcrete assigned one of four toughness performance levels. It is believed that this new procedure should provide suitable within and between laboratory reproducibility and be more suitable for purposes of differentiating between different fiber types and addition rates and specifying toughness for fiber reinforced shotcrete products than any of the existing methods.

  17. Long-period grating and its cascaded counterpart in photonic crystal fiber for gas phase measurement.

    PubMed

    Tian, Fei; Kanka, Jiri; Du, Henry

    2012-09-10

    Regular and cascaded long period gratings (LPG, C-LPG) of periods ranging from 460 to 590 ?m were inscribed in an endlessly single mode photonic crystal fiber (PCF) using CO(2) laser for sensing measurements of helium, argon and acetylene. High index sensitivities in excess of 1700 nm/RIU were achieved in both grating schemes with a period of 460 ?m. The sharp interference fringes in the transmission spectrum of C-PCF-LPG afforded not only greatly enhanced sensing resolution, but also accuracy when the phase-shift of the fringe pattern is determined through spectral processing. Comparative numerical and experimental studies indicated LP(01) to LP(03) mode coupling as the principal coupling step for both PCF-LPG and C-PCF-LPG with emergence of multi-mode coupling at shorter grating periods or longer resonance wavelengths. PMID:23037218

  18. 5394 JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 27, NO. 23, DECEMBER 1, 2009 Adaptive Receiver Structures for Fiber

    E-print Network

    Erdogan, Alper Tunga

    of the fiber channel. This is in fact the focus of this article where a receiver algorithm is based that is suitable for implementation in optical fiber communication receivers. The performance of these algorithms are illustrated through some simulation examples. Index Terms--Blind signal processing, PDM, PMD, fiber optic. I

  19. 254 JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 28, NO. 3, FEBRUARY 1, 2010 Ultrafast and Precise Interrogation of Fiber Bragg

    E-print Network

    Yao, Jianping

    of fiber Bragg grating (FBG) sensors is proposed and experimentally demonstrated. The wave- length is then verified by a numerical simulation. An FBG-based strain sensor interrogated based on the developed. Index Terms--Femtosecond fiber laser, fiber Bragg grating (FBG), higher order dispersion, real

  20. Simulating flexible fiber suspensions using a scalable immersed boundary algorithm

    NASA Astrophysics Data System (ADS)

    Wiens, Jeffrey K.; Stockie, John M.

    2015-06-01

    We present an approach for numerically simulating the dynamics of flexible fibers in a three-dimensional shear flow using a scalable immersed boundary (IB) algorithm based on Guermond and Minev's pseudo-compressible fluid solver. The fibers are treated as one-dimensional Kirchhoff rods that resist stretching, bending, and twisting, within the generalized IB framework. We perform a careful numerical comparison against experiments on single fibers performed by S. G. Mason and co-workers, who categorized the fiber dynamics into several distinct orbit classes. We show that the orbit class may be determined using a single dimensionless parameter for low Reynolds flows. Lastly, we simulate dilute suspensions containing up to hundreds of fibers using a distributed- memory computer cluster. These simulations serve as a stepping stone for studying more complex suspension dynamics including non-dilute suspensions and aggregation of fibers (also known as flocculation).

  1. Germania-based core optical fibers

    Microsoft Academic Search

    Evgeny M. Dianov; Valery M. Mashinsky

    2005-01-01

    Germania-glass-based core silica glass cladding single-mode fibers (?n up to 0.143) with a minimum loss of 20 dB\\/km at 1.9 ?m were fabricated by the modified chemical vapor deposition (MCVD) method. The fibers exhibit strong photorefractivity with the type-IIa-induced refractive-index modulation of 2×10-3. The Raman gain of 300 to 59 dB\\/(km·W) was determined at 1.07 to 1.6 ?m, respectively, in

  2. Effect of pulses from a high-power ytterbium fiber laser on a material with a nonuniform refractive index. II. Production and parameters of Nd:Y2O3 nanopowders

    NASA Astrophysics Data System (ADS)

    Osipov, V. V.; Lisenkov, V. V.; Platonov, V. V.; Orlov, A. N.; Podkin, A. V.; Savvin, I. A.

    2014-05-01

    The laser ablation of the Nd:Y2O3 target with substantially nonuniform refractive index leads to the formation of a needle-shaped surface with a needle height of 6-8 mm. An increase in the displacement velocity of the laser beam on the surface to 80 cm/s and an increase in the diameter of the laser spot at the central part of the beam waist to 430 ?m lead to a more uniform relief of the target surface and an increase in the nanopowder yield and production rate to 22% and 23 g/h, respectively. In addition, an excess of the mole content of the low-melting Nd2O3 in the powder decreases from 174 to 11% in comparison with the target. At an air pressure in the evaporation chamber of 0.8 bar, the mean sizes of nanoparticles (13-14 nm) are virtually independent of the displacement velocity of the beam on the surface (7-81 cm/s) and the rate of air flow above the target (13-70 m/s) in spite of significantly different nanopowder production rates.

  3. Seeding Steps Droplet Location

    E-print Network

    Georgiev, Atanas

    Seeding Steps Droplet Location Sample Seeding Run Crystal Detection Design and Fabrication seeding and crystal mounting Prototype Microrobotic Streak Seeding System Robotic Protein Crystal Streak Seeding Using Silicon Microtools Atanas Georgiev1, Peter Allen1, William Edstrom2, John Hunt2, Ting Song3

  4. Discrete step wavemeter

    Microsoft Academic Search

    Carl Aleksoff; Hao Yu

    2010-01-01

    Tunable lasers are used in optical metrology, but their intrinsic tuning accuracy is sometimes inadequate and an external wavemeter is then required to measure the wavelength more accurately. In this paper, we present the design of a discrete step wavemeter to measure the wavelength of the light from a tunable laser during the operation of a multi-wavelength interferometric shape measuring

  5. CONVERGING RCC STEPPED SPILLWAYS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To meet current dam safety requirements, roller compacted concrete (RCC) stepped spillways has become a popular choice is dam rehabilitation. In many cases, urbanization has changed the hazard classification of these aging watershed structures, and land rights are often not obtainable for widening ...

  6. Fast split-step wavelet collocation method for WDM system parameter optimization

    Microsoft Academic Search

    Tristan Kremp; Wolfgang Freude

    2005-01-01

    To meet rapidly increasing bandwidth requirements, extensive numerical simulations are an important optimization step for optical networks. Using a basis of cardinal functions with compact support, a new split-step wavelet collocation method (SSWCM) was developed as a general solver for the nonlinear Schrödinger equation describing pulse propagation in nonlinear optical fibers. With N as the number of discretization points, this

  7. Extended-length fiber optic carbon dioxide monitoring

    NASA Astrophysics Data System (ADS)

    Delgado-Alonso, Jesus; Lieberman, Robert A.

    2013-05-01

    This paper discusses the design and performance of fiber optic distributed intrinsic sensors for dissolved carbon dioxide, based on the use optical fibers fabricated so that their entire lengths are chemically sensitive. These fibers use a polymer-clad, silica-core structure where the cladding undergoes a large, reversible, change in optical absorbance in the presence of CO2. The local "cladding loss" induced by this change is thus a direct indication of the carbon dioxide concentration in any section of the fiber. To create these fibers, have developed a carbon dioxide-permeable polymer material that adheres well to glass, is physically robust, has a refractive index lower than fused silica, and acts as excellent hosts for a unique colorimetric indicator system that respond to CO2. We have used this proprietary material to produce carbon-dioxide sensitive fibers up to 50 meters long, using commercial optical fiber fabrication techniques. The sensors have shown a measurement range of dissolved CO2 of 0 to 1,450 mg/l (0 to 100% CO2 saturation), limit of detection of 0.3 mg/l and precision of 1.0 mg/l in the 0 to 50 mg/l dissolved CO2 range, when a 5 meter-long sensor fiber segment is used. Maximum fiber length, minimum detectable concentration, and spatial resolution can be adjusted by adjusting indicator concentration and fiber design.

  8. Polarizing 50?m core Yb-doped photonic bandgap fiber

    NASA Astrophysics Data System (ADS)

    Kong, Fanting; Gu, Guancheng; Hawkins, Thomas W.; Parsons, Joshua; Jones, Maxwell; Dunn, Christopher; Kalichevsky-Dong, Monica T.; Pulford, Benjamin; Dajani, Iyad; Saitoh, Kunimasa; Palese, Stephen P.; Cheung, Eric; Dong, Liang

    2015-03-01

    Polarizing optical fibers are important components for building compact fiber lasers with linearly polarized laser output. Conventional single-mode optical fibers with birefringence can only preserve the polarization when the incident beam is launched properly. Recent reports demonstrate that the birefringence in photonic bandgap fibers (PBFs) can provide single-polarization operation near the edge of transmission band by shifting the transmission band for the light with orthogonal polarizations. Here, we demonstrate a 50?m core Yb-doped polarizing photonic bandgap fiber (PBF) for single-polarization operation throughout the entire transmission band from 1010nm to 1170nm with a polarization extinction ratio (PER) of >5dB/m, which is >15dB/m near the short wavelength edge of the transmission band. The polarizing effect is due to the differential polarization transmission loss presented in this fiber, which is benefited from the fiber birefringence of 3.2x10-4, obtained by incorporating low-index boron-doped rods on either side of the core. The achievement is based on the fact that light at fast axis has lower effective mode index which is closer to the modes in the photonic cladding and thus to be easily coupled into cladding. A 2.6m long straight fiber was tested in a laser configuration without any polarizers to achieve single polarized laser output with a PER value of 21dB at 1026nm lasing wavelength.

  9. Bringing Nanotechnology into Fiber Opticsinto Fiber Optics

    E-print Network

    Skorobogatiy, Maksim

    .photonics.phys.polymtl.ca Canada Research Chair in Micro and Nano Photonics É l P l h i d M é lÉcole Polytechnique de Montréal www, almost no light escapes sideways http://en.wikipedia.org/wiki/Optical_Fiber #12;Fiber drawing Fiber-based) 1. Distributed sensing (T, P, ...) over 1m-1km X 1m-1km areas without any point sensors 2

  10. Trapping efficiency of fluorescent optical fibers

    NASA Astrophysics Data System (ADS)

    Weiss, Jonathan D.

    2015-02-01

    Fluorescent optical fibers are used in nuclear detection and other forms of fiber-optic sensors. The trapping efficiency of a fluorescent optical fiber is defined by the optical energy trapped (or guided) by the fiber divided by the total energy emitted within it by the fluorescers that dope the fiber core. This characteristic is clearly important in determining the size of signals from these devices. A calculation of the trapping efficiency has been performed under the assumption that the fluorescence radiation is emitted isotropically by the individual fluorescers that are uniformly distributed throughout the core and are equally likely to be excited by particles or shorter-wavelength light. At the price of increased complexity, nothing in the analysis precludes the lifting of these restrictions. What is included in this analysis is the contribution of skew rays, which, to the author's knowledge, is not presented elsewhere. A very simple expression for the trapping efficiency as a function of the cladding-to-core index ratio is derived. Also important in determining signal size is the transmission loss of the fluorescence radiation to either end of the fiber from the point of its generation. However, as it is a separate matter, it is not discussed here.

  11. Electrospun nanofiber scaffolds with gradations in fiber organization.

    PubMed

    Khandalavala, Karl; Jiang, Jiang; Shuler, Franklin D; Xie, Jingwei

    2015-01-01

    The goal of this protocol is to report a simple method for generating nanofiber scaffolds with gradations in fiber organization and test their possible applications in controlling cell morphology/orientation. Nanofiber organization is controlled with a new fabrication apparatus that enables the gradual decrease of fiber organization in a scaffold. Changing the alignment of fibers is achieved through decreasing deposition time of random electrospun fibers on a uniaxially aligned fiber mat. By covering the collector with a moving barrier/mask, along the same axis as fiber deposition, the organizational structure is easily controlled. For tissue engineering purposes, adipose-derived stem cells can be seeded to these scaffolds. Stem cells undergo morphological changes as a result of their position on the varied organizational structure, and can potentially differentiate into different cell types depending on their locations. Additionally, the graded organization of fibers enhances the biomimicry of nanofiber scaffolds so they more closely resemble the natural orientations of collagen nanofibers at tendon-to-bone insertion site compared to traditional scaffolds. Through nanoencapsulation, the gradated fibers also afford the possibility to construct chemical gradients in fiber scaffolds, and thereby further strengthen their potential applications in fast screening of cell-materials interaction and interfacial tissue regeneration. This technique enables the production of continuous gradient scaffolds, but it also can potentially produce fibers in discrete steps by controlling the movement of the moving barrier/mask in a discrete fashion. PMID:25938562

  12. Edgbaston Campus Map Index to buildings by zone

    E-print Network

    Miall, Chris

    Edgbaston Campus Map Index to buildings by zone Yellow Zone Y1 Old Gymnasium Y2 Haworth Building Y3 entrance Steps Public car park Hospital average walk time from Chancellor's Court Bus stops Library Museum

  13. Fiber optics in adverse environments

    SciTech Connect

    Lyous, P.B.

    1982-01-01

    Radiation effects in optical fibers are considered, taking into account recent progress in the investigation of radiation resistant optical fibers, radiation damage in optical fibers, radiation-induced transient absorption in optical fibers, X-ray-induced transient attenuation at low temperatures in polymer clad silica (PCS) fibers, optical fiber composition and radiation hardness, the response of irradiated optical waveguides at low temperatures, and the effect of ionizing radiation on fiber-optic waveguides. Other topics explored are related to environmental effects on components of fiber optic systems, and radiation detection systems using optical fibers. Fiber optic systems in adverse environments are also discussed, giving attention to the survivability of Army fiber optics systems, space application of fiber optics systems, fiber optic wavelength multiplexing for civil aviation applications, a new fiber optic data bus topology, fiber optics for aircraft engine/inlet control, and application of fiber optics in high voltage substations.

  14. Ceramic fiber reinforced filter

    DOEpatents

    Stinton, David P. (Knoxville, TN); McLaughlin, Jerry C. (Oak Ridge, TN); Lowden, Richard A. (Powell, TN)

    1991-01-01

    A filter for removing particulate matter from high temperature flowing fluids, and in particular gases, that is reinforced with ceramic fibers. The filter has a ceramic base fiber material in the form of a fabric, felt, paper of the like, with the refractory fibers thereof coated with a thin layer of a protective and bonding refractory applied by chemical vapor deposition techniques. This coating causes each fiber to be physically joined to adjoining fibers so as to prevent movement of the fibers during use and to increase the strength and toughness of the composite filter. Further, the coating can be selected to minimize any reactions between the constituents of the fluids and the fibers. A description is given of the formation of a composite filter using a felt preform of commercial silicon carbide fibers together with the coating of these fibers with pure silicon carbide. Filter efficiency approaching 100% has been demonstrated with these filters. The fiber base material is alternately made from aluminosilicate fibers, zirconia fibers and alumina fibers. Coating with Al.sub.2 O.sub.3 is also described. Advanced configurations for the composite filter are suggested.

  15. Tapered fiber optic sensor for potassium detection in distilled water

    NASA Astrophysics Data System (ADS)

    Yasin, M.; Pujiyanto, .; Apsari, R.; Tanjung, M.

    2015-01-01

    A simple sensor is proposed and demonstrated using a silica tapered fiber for sensing different concentration of potassium in de-ionized water. The tapered fiber is fabricated using a flame brushing technique to achieve a waist diameter and length of 10 ?m and 80 mm, respectively. For a concentration change from 0 to 50 %, the ouput signal of the sensor decreases exponentially from -10.04 dBm to -11.11 dBm with linearity of more than 92%. The increment of potassium concentration increases the refractive index of the solution, which in turn reduces the index difference between core and cladding of the tapered fiber and thus allows more light to be leaked out from the fiber. This new potassium monitoring system provides numerous advantages such as simplicity of design and low cost of production.

  16. Broadband excitation and collection in fiber-optic nonlinear endomicroscopy

    NASA Astrophysics Data System (ADS)

    Prakash Ghimire, Navin; Bao, Hongchun; Gu, Min

    2013-08-01

    Broadband excitation and collection in a fiber-optic nonlinear endomicroscope are realized by using a single hollow-core double-clad photonic crystal fiber and a gradient index lens. Femtosecond pulses with central wavelengths in the range of 750-850 nm can be directly delivered through the core of the fiber for nonlinear excitation without pre-chirping. A gradient index lens with numerical aperture 0.8 designed to operate over the near-infrared wavelength range is used for focusing the laser beam from the fiber for nonlinear excitation and for collecting the fluorescent signal from the sample. This compact system is suitable to perform nonlinear imaging of multiple fluorophors in the wavelength range of 750-850 nm.

  17. Optical characteristics of a hybrid fiber grating based on a surface long-period grating incorporating a fiber Bragg grating

    NASA Astrophysics Data System (ADS)

    Kim, Hyun-Joo; Jun, Na-Ram; Han, Young-Geun

    2012-11-01

    A hybrid grating based on a surface long-period grating (SLPG) incorporating a fiber Bragg grating (FBG) was proposed, and its optical characteristics were experimentally investigated by changing the external temperature and the ambient refractive index. For the fabrication of the hybrid grating, a FBG was firstly fabricated by using a beam scanning technique with a frequency-doubled Ar+ laser; then, some portion of the cladding region without the FBG was removed by using a side polishing technique. The SLPG was formed on a flat surface of the side-polished fiber (D-shaped fiber) by using a standard contact lithography technique. The transmission spectrum of the hybrid grating was superimposed on those for the SLPG and the FBG. Variations in the external refractive index and the temperature modified the transmission characteristics of the proposed hybrid grating. The ambient index sensitivity of the resonant peak induced by the SLPG was measured to be 810.7 nm/RIU while the resonant peak generated by the FBG was kept constant as the ambient index changed in the index range from 1.30 to 1.45. The temperature sensitivities of two resonant peaks for the SLPG and the FBG were measured to be -0.52 nm/°C and 0.01 nm/°C, respectively. Accordingly, we expect discrimination between two concurrent sensitivities, such as the external refractive index and the temperature sensitivities, to be possible when the hybrid fiber grating is implemented.

  18. Design optimization of a dual-core dispersion-compensating fiber with a high figure of merit and a large effective area for dense wavelength-division multiplexed transmission through standard G.655 fibers

    Microsoft Academic Search

    Kamna Pande; Bishnu P. Pal

    2003-01-01

    We report design optimization in terms of index-profile parameters of a dual-core dispersion-slope-compensating fiber suitable for broadband dispersion compensation in standard G.655 and G.655b single-mode fibers over the C and L bands of fiber amplifiers and additionally over the S band for the G.655b fibers. It takes into account profiles that can be achieved with state-of-the-art fabrication techniques such as

  19. Nucleic acid indexing

    DOEpatents

    Guilfoyle, Richard A. (Madison, WI); Guo, Zhen (Bellevue, WA)

    1999-01-01

    A restriction site indexing method for selectively amplifying any fragment generated by a Class II restriction enzyme includes adaptors specific to fragment ends containing adaptor indexing sequences complementary to fragment indexing sequences near the termini of fragments generated by Class II enzyme cleavage. A method for combinatorial indexing facilitates amplification of restriction fragments whose sequence is not known.

  20. Nucleic acid indexing

    DOEpatents

    Guilfoyle, Richard A. (Madison, WI); Guo, Zhen (Bellevue, WA)

    2001-01-01

    A restriction site indexing method for selectively amplifying any fragment generated by a Class II restriction enzyme includes adaptors specific to fragment ends containing adaptor indexing sequences complementary to fragment indexing sequences near the termini of fragments generated by Class II enzyme cleavage. A method for combinatorial indexing facilitates amplification of restriction fragments whose sequence is not known.