WorldWideScience

Sample records for focusung grating couplers

  1. An elastomeric grating coupler

    NARCIS (Netherlands)

    Kocabas, A.; Ay, F.; Dana, A.; Aydinli, A.

    2006-01-01

    We report on a novel nondestructive and reversible method for coupling free space light to planar optical waveguides. In this method, an elastomeric grating is used to produce an effective refractive index modulation on the surface of the optical waveguide. The external elastomeric grating binds to

  2. An elastomeric grating coupler

    Science.gov (United States)

    Kocabas, Askin; Ay, Feridun; Dâna, Aykutlu; Aydinli, Atilla

    2006-01-01

    We report on a novel nondestructive and reversible method for coupling free space light to planar optical waveguides. In this method, an elastomeric grating is used to produce an effective refractive index modulation on the surface of the optical waveguide. The external elastomeric grating binds to the surface of the waveguide with van der Waals forces and makes conformal contact without any applied pressure. As a demonstration of the feasibility of the approach, we use it to measure the refractive index of a silicon oxynitride film. This technique is nondestructive, reversible, low cost and can easily be applied to the characterization of optical materials for integrated optics.

  3. Field analysis of two-dimensional focusing grating couplers

    Science.gov (United States)

    Borsboom, P.-P.; Frankena, H. J.

    1995-05-01

    A different technique was developed by which several two-dimensional dielectric optical gratings, consisting 100 or more corrugations, were treated in a numerical reliable approach. The numerical examples that were presented were restricted to gratings made up of sequences of waveguide sections symmetric about the x = 0 plane. The newly developed method was effectively used to investigate the field produced by a two-dimensional focusing grating coupler. Focal-region fields were determined for three symmetrical gratings with 19, 50, and 124 corrugations. For focusing grating coupler with limited length, high-frequency intensity variations were noted in the focal region.

  4. High-refractive-index measurement with an elastomeric grating coupler

    NARCIS (Netherlands)

    Kocabas, Askin; Ay, Feridun; Dana, Aykutiu; Kiyat, Isa; Aydinli, Atilla

    2005-01-01

    An elastomeric grating coupler fabricated by the replica molding technique is used to measure the modal indices of a silicon-on-insulator (SOI) planar waveguide structure. Because of the van der Waals interaction between the grating mold and the waveguide, the elastomeric stamp makes conformal conta

  5. Apodized grating coupler using fully-etched nanostructures

    Science.gov (United States)

    Wu, Hua; Li, Chong; Li, Zhi-Yong; Guo, Xia

    2016-08-01

    A two-dimensional apodized grating coupler for interfacing between single-mode fiber and photonic circuit is demonstrated in order to bridge the mode gap between the grating coupler and optical fiber. The grating grooves of the grating couplers are realized by columns of fully etched nanostructures, which are utilized to digitally tailor the effective refractive index of each groove in order to obtain the Gaussian-like output diffractive mode and then enhance the coupling efficiency. Compared with that of the uniform grating coupler, the coupling efficiency of the apodized grating coupler is increased by 4.3% and 5.7%, respectively, for the nanoholes and nanorectangles as refractive index tunes layer. Project supported by the National Natural Science Foundation of China (Grant Nos. 61222501, 61335004, and 61505003), the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20111103110019), the Postdoctoral Science Foundation of Beijing Funded Project, China (Grant No. Q6002012201502), and the Science and Technology Research Project of Jiangxi Provincial Education Department, China (Grant No. GJJ150998).

  6. 3D Printed Terahertz Focusing Grating Couplers

    Science.gov (United States)

    Jahn, David; Weidenbach, Marcel; Lehr, Jannik; Becker, Leonard; Beltrán-Mejía, Felipe; Busch, Stefan F.; Balzer, Jan C.; Koch, Martin

    2017-02-01

    We have designed, constructed and characterized a grating that focuses electromagnetic radiation at specific frequencies out of a dielectric waveguide. A simple theoretical model predicts the focusing behaviour of these chirped gratings, along with numerical results that support our assumptions and improved the grating geometry. The leaky waveguide was 3D printed and characterized at 120 GHz demonstrating its potential for manipulating terahertz waves.

  7. Numerical Analysis on Transmission Characteristics of a Bragg Grating Assisted Mismatched Fiber Coupler

    Institute of Scientific and Technical Information of China (English)

    WEI Daoping; JIANG Zhong'ao; ZHAO Yucheng; JIAN Shuisheng

    2000-01-01

    Based on mode-coupled theory, a Bragg grating assisted mismatched fiber coupler is analyzed theoretically. At the same time, a detailed numerical analysis on transmission characteristics of the coupler is carried out when it considers the arcs of two fibers in the coupling region of the coupler or not, and the optimized design on the Bragg grating assisted mismatched fiber coupler for wavelength-division multiplexing/ demultiplexing is proposed.

  8. Laser Trimming for Adjustment of Grating Offset in Phase-Shifted Fiber Grating Coupler for All-Optical Switching Application

    Institute of Scientific and Technical Information of China (English)

    Hirohisa; Yokota; Yutaka; Sasaki

    2003-01-01

    We theoretically investigated laser trimming to adjust grating offset in phase-shifted fiber grating coupler (FGC) for all-optical switching application. It was clarified that the trimming made the extinction ratio higher in all-optical FGC switch.

  9. Stratified waveguide grating coupler for normal fiber incidence.

    Science.gov (United States)

    Wang, Bin; Jiang, Jianhua; Chambers, Diana M; Cai, Jingbo; Nordin, Gregory P

    2005-04-15

    We propose a new stratified waveguide grating coupler (SWGC) to couple light from a fiber at normal incidence into a planar waveguide. SWGCs are designed to operate in the strong coupling regime without intermediate optics between the fiber and the waveguide. Two-dimensional finite-difference time-domain simulation in conjunction with microgenetic algorithm optimization shows that approximately 72% coupling efficiency is possible for fiber (core size of 8.3 microm and delta=0.36%) to slab waveguide (1.2-microm core and delta=3.1%) coupling. We show that the phase-matching and Bragg conditions are simultaneously satisfied through the fundamental leaky mode.

  10. High-refractive-index measurement with an elastomeric grating coupler

    Science.gov (United States)

    Kocabas, Askin; Ay, Feridun; Dâna, Aykutlu; Kiyat, Isa; Aydinli, Atilla

    2005-12-01

    An elastomeric grating coupler fabricated by the replica molding technique is used to measure the modal indices of a silicon-on-insulator (SOI) planar waveguide structure. Because of the van der Waals interaction between the grating mold and the waveguide, the elastomeric stamp makes conformal contact with the waveguide surface, inducing a periodic index perturbation at the contact region. The phase of the incident light is changed to match the guided modes of the waveguide. The modal and bulk indices are obtained by measuring the coupling angles. This technique serves to measure the high refractive index with a precision better than 10-3 and allows the elastomeric stamp to be removed without damaging the surface of the waveguide.

  11. Grating-assisted vertical couplers for signal routing in multilayer integrated optical networks

    Science.gov (United States)

    Calò, Giovanna; Petruzzelli, Vincenzo

    2017-03-01

    Grating-assisted vertical couplers, which behave as add-drop filters, are proposed for wavelength routing of the signal among the different layers of on-chip multilayer optical networks. The device implements a 2×2 wavelength router which can be assembled into higher-order three-dimensional matrices. In particular, simple design criteria are found through a rapid and efficient optimization approach based on the mode analysis and demonstrated by the Finite Difference Time Domain (FDTD) simulations. The proposed numerical method is valid either for in-plane or for vertical grating-assisted couplers and it requires negligible computational effort. Different configurations of grating-assisted vertical couplers are designed and their spectral behavior is analyzed by the FDTD. The proposed devices achieve low values of the crosstalk between the different ports (below -20 dB) and of the input reflection (below -15 dB).

  12. Ultrahigh-efficiency apodized grating coupler using fully etched photonic crystals

    DEFF Research Database (Denmark)

    Ding, Yunhong; Ou, Haiyan; Peucheret, Christophe

    2013-01-01

    We present an efficient method to design apodized grating couplers with Gaussian output profiles for efficient coupling between standard single mode fibers and silicon chips. An apodized grating coupler using fully etched photonic crystal holes on the silicon-on-insulator platform is designed......, and fabricated in a single step of lithography and etching. An ultralow coupling loss of x2212;1.74x2009;x2009;dB (67% coupling efficiency) with a 3xA0;dB bandwidth of 60xA0;nm is experimentally measured....

  13. On-chip Mode Multiplexer Based on a Single Grating Coupler

    DEFF Research Database (Denmark)

    Ding, Yunhong; Ou, Haiyan; Xu, Jing;

    2012-01-01

    A two-mode multiplexer based on a single grating coupler is proposed and demonstrated on a silicon chip. The LP01 and LP11 modes of a few-mode fiber are excited from TE0 and TE1 silicon waveguide modes....

  14. Topology optimization of grating couplers for the efficient excitation of surface plasmons

    DEFF Research Database (Denmark)

    Andkjær, Jacob Anders; Sigmund, Ole; Nishiwaki, Shinji

    2010-01-01

    We propose a methodology for a systematic design of grating couplers for efficient excitation of surface plasmons at metal-dielectric interfaces. The methodology is based on a two-dimensional topology optimization formulation based on the H-polarized scalar Helmholtz equation and finite-element m...

  15. Grating couplers in silicon-on-insulator: The role of photonic guided resonances on lineshape and bandwidth

    Science.gov (United States)

    Passoni, M.; Gerace, D.; Carroll, L.; Andreani, L. C.

    2017-01-01

    Most grating couplers for silicon photonics are designed to match the approximately 10 μm mode-field diameter (MFD) of single-mode telecom fibres. In this letter, we analyse grating-coupler designs in the Silicon-on-Insulator (SOI) platform in a wide range of MFDs (4-100 μm) and related footprints, to give a physical understanding of the trends in efficiency and lineshape of the corresponding coupling spectra. We show that large-footprint grating couplers have an intrinsic Lorentzian lineshape that is determined by the quasi-guided photonic modes (or guided resonances) of the corresponding photonic crystal slab, while small-footprint grating couplers have a Gaussian lineshape resulting from the k-space broadening of the incident mode. The crossover between the two regimes is characterized by Voigt lineshapes. Multi-objective particle-swarm optimisation of selected small-footprint apodized grating-couplers is then used to locate the "Pareto fronts;" along which the highest coupling efficiency is achieved for a given bandwidth. This approach identifies several high-efficiency 220 nm SOI grating coupler designs with 1 dB bandwidths exceeding 100 nm. Such grating couplers are ideally suited for broadband photonic applications, such as wavelength-division multiplexing and environmental sensing, and are compatible with commercially available ultra-high numerical aperture fibres.

  16. Single etch grating couplers for mass fabrication with DUV lithography

    National Research Council Canada - National Science Library

    Halir, R; Zavargo-Peche, L; Xu, Dan-Xia; Cheben, Pavel; Ma, Rubin; Schmid, Jens Holger; Janz, Siegfried; Densmore, Adam; Ortega-Moñux, A; Molina-Fernández, Í; Fournier, M; Fédeli, J.-M

    2012-01-01

    ... efficiencies with a single etch step, thereby significantly reducing fabrication complexity. Here we demonstrate that such couplers can be fabricated on a large scale with ultra-violet lithography, achieving a 5 dB coupling efficiency at 1,550 nm...

  17. Direct synthesis of strong grating couplers for efficient integrated optical beam forming

    CERN Document Server

    Urošević, Stevan

    2014-01-01

    We describe a computational method for the direct synthesis of non-uniform optical grating coupler geometries on a photonic chip to form beams of arbitrary field distribution. The method is applied to grating couplers using high index contrast, typically encountered in silicon photonics for fiber-to-chip coupling and chip-based optical beam forming. We use a numerical synthesis approach to synthesize a non-uniform structure that emits a particular desired beam pattern, and explicitly take into account chirp generated by non-uniform gratings. Even for strong, short gratings, and for designs within the constraints of existing standard 45nm SOI-CMOS foundry process, mode overlaps exceeding 90% can be obtained. We discuss strengths and shortcomings of the approach and particular implementation. We demonstrate the method by synthesizing non-uniform grating coupler designs for efficient mode matching to optical fiber modes or single free-space beam modes with Gaussian magnitude and flat phase front and show that go...

  18. Fiber-chip grating coupler based on interleaved trenches with directionality exceeding 95.

    Science.gov (United States)

    Alonso-Ramos, C; Cheben, P; Ortega-Moñux, A; Schmid, J H; Xu, D-X; Molina-Fernández, I

    2014-09-15

    We propose a fiber-chip grating coupler that interleaves the standard full and shallow etch trenches in a 220 nm thick silicon layer to provide a directionality upward exceeding 95%. By adjusting the separation between the two sets of trenches, constructive interference is achieved in the upward direction independent of the bottom oxide thickness and without any bottom reflectors, overlays, or customized etch depths. We implement a transverse subwavelength structure in the first two grating periods to minimize back-reflections. The grating coupler has a calculated coupling efficiency of CE~-1.05 dB with a 1 dB bandwidth of 30 nm and minimum feature size of 100 nm, compatible with deep-UV lithography.

  19. Miniaturized Bragg-grating couplers for SiN-photonic crystal slabs.

    Science.gov (United States)

    Barth, Carlo; Wolters, Janik; Schell, Andreas W; Probst, Jürgen; Schoengen, Max; Löchel, Bernd; Kowarik, Stefan; Benson, Oliver

    2015-04-20

    We report on an experimental and theoretical investigation of an integrated Bragg-like grating coupler for near-vertical scattering of light from photonic crystal waveguides with an ultra-small footprint of a few lattice constants only. Using frequency-resolved measurements, we find the directional properties of the scattered radiation and prove that the coupler shows a good performance over the complete photonic bandgap. The results compare well to analytical considerations regarding 1d-scattering phenomena as well as to FDTD simulations.

  20. On-chip fluorescence excitation and collection by focusing grating couplers

    Science.gov (United States)

    Kerman, Sarp; Vercruysse, Dries; Claes, Tom; Ul Hasan, Mahmud; Neutens, Pieter; Mukund, Vignesh; Rottenberg, Xavier; Lagae, Liesbet; Van Dorpe, Pol

    2016-05-01

    Fluorescence detection is a commonly used technique to detect particles. Microscopes are used for the fluorescence detection of the micro-particles. However, the conventional microscopes are bulky. It is cumbersome to integrate all the equipment used for detection in one setup. They can be replaced by photonic chips for the detection of micro-particles such as cells. Most of the biological detection techniques require the utilization of the visible range of the spectrum. SiN as a waveguide material stands out for biological applications due to its transparency in the visible spectrum. Specifically designed grating couplers can be exploited to focus from inside SiN waveguides at a designated location above the chip. Those SiN focusing grating couplers can mimic microscope objectives for on-chip biological detection applications such as fluorescence and Raman spectroscopy. In this report, we present a 2D SiN focusing grating coupler. We study the effect of the grating design on the focus properties of visible light using finite-difference time-domain simulations.

  1. Suspended mid-infrared fiber-to-chip grating couplers for SiGe waveguides

    Science.gov (United States)

    Favreau, Julien; Durantin, Cédric; Fédéli, Jean-Marc; Boutami, Salim; Duan, Guang-Hua

    2016-03-01

    Silicon photonics has taken great importance owing to the applications in optical communications, ranging from short reach to long haul. Originally dedicated to telecom wavelengths, silicon photonics is heading toward circuits handling with a broader spectrum, especially in the short and mid-infrared (MIR) range. This trend is due to potential applications in chemical sensing, spectroscopy and defense in the 2-10 μm range. We previously reported the development of a MIR photonic platform based on buried SiGe/Si waveguide with propagation losses between 1 and 2 dB/cm. However the low index contrast of the platform makes the design of efficient grating couplers very challenging. In order to achieve a high fiber-to-chip efficiency, we propose a novel grating coupler structure, in which the grating is locally suspended in air. The grating has been designed with a FDTD software. To achieve high efficiency, suspended structure thicknesses have been jointly optimized with the grating parameters, namely the fill factor, the period and the grating etch depth. Using the Efficient Global Optimization (EGO) method we obtained a configuration where the fiber-to-waveguide efficiency is above 57 %. Moreover the optical transition between the suspended and the buried SiGe waveguide has been carefully designed by using an Eigenmode Expansion software. Transition efficiency as high as 86 % is achieved.

  2. Design, fabrication, and characterisation of fully etched TM grating coupler for photonic integrated system-in-package

    Science.gov (United States)

    Gili-de-Villasante, Oriol; Tcheg, Paul; Wang, Bei; Suna, Alpaslan; Giannoulis, Giannis; Lazarou, Ioannis; Apostolopoulos, Dimitrios; Avramopoulos, Hercules; Pleros, Nikos; Baus, Matthias; Karl, Matthias; Tekin, Tolga

    2012-06-01

    Grating couplers are the best solution for testing nano-photonic circuits. Their main benefit is that they allow access via an optical fiber from the top and therefore there is no need to dice the chip and prepare the facets crucially. In the PLATON project grating couplers were designed to couple TM mode into and out of the SOI waveguides. Simulations came up with a grating coupler layout capable of theoretical coupling losses lower than 3dB for 1550 nm in TM configuration. A fully etched grating structure was chosen for fabrication simplicity and the optimal filling factor was found. The structures were fabricated using proximity error correction (PEC) and show a uniform coupling efficiency for all couplers. Therefore they are well-suited for all applications which demand for stable fiber-to-chip coupling. The spectral response of the structures was measured from 1500 to 1580 nm with 2 nm step and measuring the fiber-tofiber losses of three straight waveguides equipped with three grating couplers with different gap widths. The optimal grating period exhibits adequate coupling losses of 3.23 dB per coupler at 1557 nm, being therefore the most promising design.

  3. Refractive index engineering with subwavelength gratings for efficient microphotonic couplers and planar waveguide multiplexers.

    Science.gov (United States)

    Cheben, Pavel; Bock, Przemek J; Schmid, Jens H; Lapointe, Jean; Janz, Siegfried; Xu, Dan-Xia; Densmore, Adam; Delâge, André; Lamontagne, Boris; Hall, Trevor J

    2010-08-01

    We use subwavelength gratings (SWGs) to engineer the refractive index in microphotonic waveguides, including practical components such as input couplers and multiplexer circuits. This technique allows for direct control of the mode confinement by changing the refractive index of a waveguide core over a range as broad as 1.6-3.5 by lithographic patterning. We demonstrate two experimental examples of refractive index engineering, namely, a microphotonic fiber-chip coupler with a coupling loss as small as -0.9dB and minimal wavelength dependence and a planar waveguide multiplexer with SWG nanostructure, which acts as a slab waveguide for light diffracted by the grating, while at the same time acting as a lateral cladding for the strip waveguide. This yields an operation bandwidth of 170nm for a device size of only approximately 160microm x100microm.

  4. Optical true time delay based on contradirectional couplers with single sidewall-modulated Bragg gratings

    Science.gov (United States)

    Wang, Xu; Liao, Shasha; Dong, Jianji

    2016-11-01

    We propose and demonstrate optical true time delay using tapered SOI contradirectional couplers with single sidewallmodulated Bragg gratings. The contradirectional couplers consist of two tapered rib waveguides with different width, and the Bragg gratings are modulated in the inner sidewall of the wider one. The optical signal is launched from the wide waveguide and coupled to the narrow waveguide through the Bragg gratings structure. Along the direction of light propagation, the waveguide width varies linearly, so the reflection wavelength is different at different positions. Therefore, linear delay line can be realized within the grating passband using the present structure. In the simulation, grating period is 310nm and grating number is 2400, corresponding to the grating length of 744μm. Using 2.5D FDTD simulation, the current structure can realize optical group delay of 20ps within bandwidth of 18nm. The proposed device is fabricated on a 220nm SOI chip with Electron Beam Lithography (EBL) and Inductively Coupled Plasma (ICP) etching. In the experiment, continuous light is modulated by 10GHz radio-frequency signal and travel through the chip, which is finally detected by the oscilloscope. By adjusting the wavelength of input light, group delay of different wavelength are recorded by the oscilloscope. The experimental results show that group delay of 28ps is realized within the bandwidth of 20nm. In the end, the drift of the reflection spectrum and delay lines under different temperature are analyzed. The reflection spectrum drifts 0.1nm/°C and causes redshift of the corresponding delay line.

  5. On-chip grating coupler array on the SOI platform for fan-in/fan-out of MCFs with low insertion loss and crosstalk

    DEFF Research Database (Denmark)

    Ding, Yunhong; Ye, Feihong; Peucheret, Christophe

    2015-01-01

    We report the design and fabrication of a compact multi-core fiber fan-in/fan-out using a grating coupler array on the SOI platform. The grating couplers are fully-etched, enabling the whole circuit to be fabricated in a single lithography and etching step. Thanks to the apodized design for the g......We report the design and fabrication of a compact multi-core fiber fan-in/fan-out using a grating coupler array on the SOI platform. The grating couplers are fully-etched, enabling the whole circuit to be fabricated in a single lithography and etching step. Thanks to the apodized design...

  6. An Efficient Large-Area Grating Coupler for Surface Plasmon Polaritons

    CERN Document Server

    Koev, Stephan T; Lezec, Henri J; Aksyuk, Vladimir A

    2011-01-01

    We report the design, fabrication and characterization of a periodic grating of shallow rectangular grooves in a metallic film with the goal of maximizing the coupling efficiency of an extended plane wave (PW) of visible or near-infrared light into a single surface plasmon polariton (SPP) mode on a flat metal surface. A PW-to-SPP power conversion factor > 45 % is demonstrated at a wavelength of 780 nm, which exceeds by an order of magnitude the experimental performance of SPP grating couplers reported to date at any wavelength. Conversion efficiency is maximized by matching the dissipative SPP losses along the grating surface to the local coupling strength. This critical coupling condition is experimentally achieved by tailoring the groove depth and width using a focused ion beam.

  7. Back-reflecting interferometeric sensor based on grating coupler on a planar waveguide

    CERN Document Server

    Demeter, Anat

    2015-01-01

    We present a one-port sensor based on a single diffraction grating delineated over a planar optical waveguide. Distinctly to previously reported devices, the grating here is used not only as I/O coupler, but also provides a built-in reference beam which is basically unaffected by the sensing process as manifested in changes of the effective refractive index of the waveguide. The sensing process causes two effects simultaneously: a change in the angle of the out-coupled beam and a change in the phase accumulated by that beam. Both changes can be determined by their conjunction with the reference beam back-diffracted directly by the grating. These two effects are expected to have despair sensitivities, the angle changing effect being coarse and the interferometric phase-change effect being highly sensitive. Sensing simultaneously at two different scales will translate into a large sensing dynamic range.

  8. Flip-chip assembly of VCSELs to silicon grating couplers via laser fabricated SU8 prisms.

    Science.gov (United States)

    Kaur, K S; Subramanian, A Z; Cardile, P; Verplancke, R; Van Kerrebrouck, J; Spiga, S; Meyer, R; Bauwelinck, J; Baets, R; Van Steenberge, G

    2015-11-02

    This article presents the flip-chip bonding of vertical-cavity surface-emitting lasers (VCSELs) to silicon grating couplers (GCs) via SU8 prisms. The SU8 prisms are defined on top of the GCs using non-uniform laser ablation process. The prisms enable perfectly vertical coupling from the bonded VCSELs to the GCs. The VCSELs are flip-chip bonded on top of the silicon GCs employing the laser-induced forward transfer (LIFT)-assisted thermocompression technique. An excess loss of transmission experiments performed on the bonded assemblies with clear eye openings up to 20 Gb/s are also presented.

  9. Silica-Based Arrayed Waveguide Grating with Flattened Spectral Response Using a Multimode Interference Coupler

    Institute of Scientific and Technical Information of China (English)

    TANG Yan-Zhe; JIA Ke-Miao; LI Bai-Yang; YANG Jian-Yi; JIANG Xiao-Qing; WU Ya-Ming; WANG Yue-Lin

    2004-01-01

    @@ We designed and fabricated an arrayed waveguide grating based on silica-on-silicon materials with flattened spectral response by adding a multimode interference coupler in the input region. The theoretical analysis and calculation are given. The device has worked effectively and has been tested with the passband 0.43 nm at 1 dB,0.72nm at 3dB and 1.56nm at 20dB respectively, at a cost of power penalty of about 1.5dB. The crosstalk is less than -30 dB, owing to the high-resolution photomask and well-controlled fabrication processes.

  10. Highly efficient vertical fiber interfacing grating coupler with bilayer anti-reflection cladding and backside metal mirror

    Science.gov (United States)

    Zhang, Zanyun; Huang, Beiju; Zhang, Zan; Cheng, Chuantong; Liu, Hongwei; Li, Hongqiang; Chen, Hongda

    2017-05-01

    A highly efficient bidirectional grating coupler for perfectly vertical coupling is designed. With a Si3N4/SiO2 bilayer structure and a backside metal mirror acting as anti-reflection cladding (ARC) and substrate reflector respectively, the coupling efficiency can be greatly enhanced for a cost-effective uniform grating coupler. To maximize the grating coupling, all the grating parameters including the bilayer thicknesses are fully optimized using numerical simulation method. As a design trade-off between coupling efficiency (CE) and optical bandwidth (OB), CE of 88.3% (-0.54 dB) and 1-dB bandwidth of 61 nm can be obtained. In addition, this grating coupler shows strong fiber misalignment tolerance. With a 2 μm fiber misalignment, the coupling loss increases by less than 0.5 dB and the up-reflection loss increases by less than 2 dB. Also it is found that the splitting behavior of the grating is quite stable near the grating resonant wavelength. Such characteristics make this device very attractive for low-cost photonic packaging and Mach-Zehnder type device applications. In addition, two optimal designs are presented based on the Particle Swarm Optimization (PSO) method and genetic algorithm (GA). Numerical calculated results show that the coupling efficiency at center wavelength can be further improved compared to that of the balanced design. However, the optical bandwidth suffer at a expense. At last, Fourier analysis of the grating is carried out to analyze the optical field profile and frequency spectrum of the grating region. It is believed such a grating structure can provide flexible designs for different coupler requirements and applications.

  11. Efficient silicon PIC mode multiplexer using grating coupler array with aluminum mirror for few-mode fiber

    DEFF Research Database (Denmark)

    Ding, Yunhong; Yvind, Kresten

    2015-01-01

    We demonstrate a silicon PIC mode multiplexer using grating couplers. An aluminum mirror is introduced for coupling efficiency improvement. A highest coupling efficiency of –10.6 dB with 3.7 dB mode dependent coupling loss is achieved.......We demonstrate a silicon PIC mode multiplexer using grating couplers. An aluminum mirror is introduced for coupling efficiency improvement. A highest coupling efficiency of –10.6 dB with 3.7 dB mode dependent coupling loss is achieved....

  12. High-efficiency fully etched fiber-chip grating couplers with subwavelength structures for datacom and telecom applications

    Science.gov (United States)

    Benedikovic, Daniel; Cheben, Pavel; Schmid, Jens H.; Xu, Dan-Xia; Lapointe, Jean; Wang, Shurui; Janz, Siegfried; Halir, Robert; Ortega-Moñux, Alejandro; Dado, Milan

    2015-05-01

    Surface grating couplers are key components to couple light between planar waveguide circuits in silicon-on-insulator (SOI) platform and optical fibers. Here, we demonstrate by using simulations and experiments that a high coupling efficiency can be achieved for an arbitrary buried oxide thickness by judicious adjustment of the grating radiation angle. The coupler strength is engineered by subwavelength structures, which have pitch and feature sizes smaller than the wavelength of light propagating through it, thereby frustrating diffraction effects and behaving as a homogeneous media with an adjustable equivalent refractive index. This makes it possible to apodize the grating coupler with a preferred single etch fabrication process. The coupling efficiency of the grating coupler is optimized for operating with the transverse electric (TE) polarization state at the wavelengths near 1.3 µm and 1.55 µm, which are the bands relevant for datacom and telecom interconnects applications, respectively. The design and analysis of the grating coupler is carried out using two-dimensional (2-D) Fourier-eigenmode expansion method (F-EEM) and finite difference time domain (FDTD) method. The simulations show a peak fiber-chip coupling efficiency of ‒1:61 dB and ‒ 1:97 dB at 1.3 µm and 1.55 µm wavelengths, respectively, with a minimum feature size of 100 nm, compatible with 193 nm deep-ultraviolet (DUV) lithography. The measurements of our fabricated continuously apodized grating coupler demonstrate fiber-chip coupling efficiency of ‒ 2:16 dB at a wavelength near 1.55 µm with a 3 dB bandwidth of 64 nm. These results open promising prospects for low-cost and high-volume fabrication of surface grating couplers in SOI using 193 nm DUV lithography, which is now used in several silicon photonics foundries. It is also predicted that a coupling efficiency as high as ‒ 0:42 dB can be achieved for the coupler structure with a bottom dielectric mirror.

  13. Single-etch subwavelength engineered fiber-chip grating couplers for 1.3 µm datacom wavelength band.

    Science.gov (United States)

    Benedikovic, Daniel; Alonso-Ramos, Carlos; Cheben, Pavel; Schmid, Jens H; Wang, Shurui; Halir, Robert; Ortega-Moñux, Alejandro; Xu, Dan-Xia; Vivien, Laurent; Lapointe, Jean; Janz, Siegfried; Dado, Milan

    2016-06-13

    We report, for the first time, on the design and experimental demonstration of fiber-chip surface grating couplers based on subwavelength grating engineered nanostructure operating in the low fiber chromatic dispersion window (around 1.3 μm wavelengths), which is of great interest for short-reach data communication applications. Our coupler designs meet the minimum feature size requirements of large-volume deep-ultraviolet stepper lithography processes. The fiber-chip couplers are implemented in a standard 220-nm-thick silicon-on-insulator (SOI) platform and are fabricated by using a single etch process. Several types of couplers are presented, specifically the uniform, the apodized, and the focusing designs. The measured peak coupling efficiency is -2.5 dB (56%) near the central wavelength of 1.3 μm. In addition, by utilizing the technique of the backside substrate metallization underneath the grating couplers, the coupling efficiency of up to -0.5 dB (89%) is predicted by Finite Difference Time Domain (FDTD) calculations.

  14. Experimental demonstration of an apodized-imaging chip-fiber grating coupler for Si3N4 waveguides.

    Science.gov (United States)

    Chen, Yang; Domínguez Bucio, Thalia; Khokhar, Ali Z; Banakar, Mehdi; Grabska, Katarzyna; Gardes, Frederic Y; Halir, Robert; Molina-Fernández, Íñigo; Cheben, Pavel; He, Jian-Jun

    2017-09-15

    A silicon nitride waveguide is a promising platform for integrated photonics, particularly due to its low propagation loss compared to other complementary metal-oxide-semiconductor compatible waveguides, including silicon-on-insulator. Input/output coupling in such thin optical waveguides is a key issue for practical implementations. Fiber-to-chip grating couplers in silicon nitride usually exhibit low coupling efficiency because the moderate index contrast leads to weak radiation strengths and poor directionality. Here, we present the first, to the best of our knowledge, experimental demonstration of a recently proposed apodized-imaging fiber-to-chip grating coupler in silicon nitride that images an in-plane waveguide mode to an optical fiber placed at a specific distance above the chip. By employing amplitude and phase apodization, the diffracted optical field of the grating is matched to the fiber mode. High grating directionality is achieved by using staircase grating teeth, which produce a blazing effect. Experimental results demonstrate an apodized-imaging grating coupler with a record coupling efficiency of -1.5  dB and a 3 dB bandwidth of 60 nm in the C-band.

  15. A fiber-integrated optical component fabricated via photopolymerization: Mode-selective grating coupler

    Science.gov (United States)

    Sümer, Can; Dinleyici, M. Salih

    2013-11-01

    We demonstrate a mode-selective directional coupler based on a grating structure, which is fabricated by laser direct-writing on a photopolymer thin film. The device is implemented on the flat planar surface of the D-Fiber, enabling fiber integration, where an Acrylamide/Polyvinyl Alcohol based photopolymer material is used in the fabrication of the device. While the refractive index modulation properties of the polymer material are well known, surface relief and corrugation properties due to photopolymerization are investigated in this study. Theoretical model of the device is presented together with the optimization and simulation results of the final device; experimental results have been found to be in good agreement with simulations.

  16. Fabrication defects and grating couplers in III-nitride photonic crystal nanobeam lasers (Conference Presentation)

    Science.gov (United States)

    Rousseau, Ian; Sánchez Arribas, Irene; Carlin, Jean-François; Butté, Raphaël.; Grandjean, Nicolas

    2016-04-01

    We report a numerical and experimental investigation of fabrication tolerances and outcoupling in optically pumped III-nitride nanolasers operating near λ = 460 nm, in which feedback is provided by a one-dimensional photonic crystal nanobeam cavity and gain is supplied by a single InGaN/GaN quantum well. Using this platform, we and others previously demonstrated single-μW lasing thresholds due to the high βQ-product inherent to the nanobeam geometry (β is spontaneous emission coupling fraction into desired mode). In this work, we improved the fraction of emission emitted into our microscope's light cone by combining a redesigned photonic crystal cavity (c.f. [3]) with a cross-grating coupler with period approximately twice the photonic crystal lattice constant. The samples were fabricated in epitaxial III-nitride layers grown on (111) silicon substrates using metal organic vapor phase epitaxy. The photonic crystal and output couplers were patterned using a single electron beam lithography exposure and subsequently transferred to the underlying III-nitride layers using dry etching. The nanobeams were then suspended via vapor phase etching of silicon in XeF2. Scanning electron microscopy cross-sections revealed high-aspect ratio (>5), sub-70 nanometer diameter holes with near-vertical sidewalls. Fabrication-induced geometry errors were characterized by processing scanning electron micrographs with custom critical dimension software. Using UV micro-photoluminescence spectroscopy at room temperature, we measured the nanobeams' emission intensity, far-field profile, and quality factor. By comparing more than ten nominally identical nanobeams for each geometry with finite-difference time-domain simulations taking into account the geometrical deviations measured during fabrication, we characterized the role of fabrication-induced imperfections. Finally, we explored the trade-off between the quality factor and collected signal via lithographic variations of the output

  17. Generic Wavelength-routed Optical Router (GWOR) based on grating-assisted vertical couplers for multilayer optical networks

    Science.gov (United States)

    Calò, Giovanna; Petruzzelli, Vincenzo

    2016-05-01

    A Generic Wavelength-routed Optical Router (GWOR) based on grating-assisted vertical couplers is proposed to be used as 4×4 routing matrix in multilayer optical networks. The device exploits, as basic building blocks, four vertical grating-assisted couplers made of three vertically stacked waveguides. The central waveguide is patterned with a periodic Bragg grating that guarantees the wavelength routing of the signal at the Bragg wavelength. The design and the analysis of the grating-assisted vertical couplers, performed by two different numerical methods, the Bidirectional Beam Propagation Method based on the Method of Lines (MoL-BBPM) and the Finite Difference Time Domain (FDTD) method, are reported. Moreover, the GWOR matrix is analyzed, with a very limited computational effort, by suitably composing the numerically calculated transmittances of the 2×2 elementary building blocks. The proposed GWOR matrix achieves low values of the insertion loss (i.e. maximum insertion loss IL=0.2 dB) and crosstalk below -15 dB.

  18. Design and characterization of low-loss 2D grating couplers for silicon photonics integrated circuits

    Science.gov (United States)

    Lacava, C.; Carrol, L.; Bozzola, A.; Marchetti, R.; Minzioni, P.; Cristiani, I.; Fournier, M.; Bernabe, S.; Gerace, D.; Andreani, L. C.

    2016-03-01

    We present the characterization of Silicon-on-insulator (SOI) photonic-crystal based 2D grating-couplers (2D-GCs) fabricated by CEA-Leti in the frame of the FP7 Fabulous project, which is dedicated to the realization of devices and systems for low-cost and high-performance passives-optical-networks. On the analyzed samples different test structures are present, including 2D-GC connected to another 2D-GC by different waveguides (in a Mach-Zehnder like configuration), and 2D-GC connected to two separate 2D-GCs, so as to allow a complete assessment of different parameters. Measurements were carried out using a tunable laser source operating in the extended telecom bandwidth and a fiber-based polarization controlling system at the input of device-under-test. The measured data yielded an overall fiber-to-fiber loss of 7.5 dB for the structure composed by an input 2D-GC connected to two identical 2D-GCs. This value was obtained at the peak wavelength of the grating, and the 3-dB bandwidth of the 2D-GC was assessed to be 43 nm. Assuming that the waveguide losses are negligible, so as to make a worst-case analysis, the coupling efficiency of the single 2D-GC results to be equal to -3.75 dB, constituting, to the best of our knowledge, the lowest value ever reported for a fully CMOS compatible 2D-GC. It is worth noting that both the obtained values are in good agreement with those expected by the numerical simulations performed using full 3D analysis by Lumerical FDTD-solutions.

  19. Nanophotonic lab-on-a-chip platforms including novel bimodal interferometers, microfluidics and grating couplers.

    Science.gov (United States)

    Duval, Daphné; González-Guerrero, Ana Belén; Dante, Stefania; Osmond, Johann; Monge, Rosa; Fernández, Luis J; Zinoviev, Kirill E; Domínguez, Carlos; Lechuga, Laura M

    2012-05-08

    One of the main limitations for achieving truly lab-on-a-chip (LOC) devices for point-of-care diagnosis is the incorporation of the "on-chip" detection. Indeed, most of the state-of-the-art LOC devices usually require complex read-out instrumentation, losing the main advantages of portability and simplicity. In this context, we present our last advances towards the achievement of a portable and label-free LOC platform with highly sensitive "on-chip" detection by using nanophotonic biosensors. Bimodal waveguide interferometers fabricated by standard silicon processes have been integrated with sub-micronic grating couplers for efficient light in-coupling, showing a phase resolution of 6.6 × 10(-4)× 2π rad and a limit of detection of 3.3 × 10(-7) refractive index unit (RIU) in bulk. A 3D network of SU-8 polymer microfluidics monolithically assembled at the wafer-level was included, ensuring perfect sealing and compact packaging. To overcome some of the drawbacks inherent to interferometric read-outs, a novel all-optical wavelength modulation system has been implemented, providing a linear response and a direct read-out of the phase variation. Sensitivity, specificity and reproducibility of the wavelength modulated BiMW sensor has been demonstrated through the label-free immunodetection of the human hormone hTSH at picomolar level using a reliable biofunctionalization process.

  20. Capturing reflected cladding modes from a fiber Bragg grating with a double-clad fiber coupler.

    Science.gov (United States)

    Baiad, Mohamad Diaa; Gagné, Mathieu; Lemire-Renaud, Simon; De Montigny, Etienne; Madore, Wendy-Julie; Godbout, Nicolas; Boudoux, Caroline; Kashyap, Raman

    2013-03-25

    We present a novel measurement scheme using a double-clad fiber coupler (DCFC) and a fiber Bragg grating (FBG) to resolve cladding modes. Direct measurement of the optical spectra and power in the cladding modes is obtained through the use of a specially designed DCFC spliced to a highly reflective FBG written into slightly etched standard photosensitive single mode fiber to match the inner cladding diameter of the DCFC. The DCFC is made by tapering and fusing two double-clad fibers (DCF) together. The device is capable of capturing backward propagating low and high order cladding modes simply and efficiently. Also, we demonstrate the capability of such a device to measure the surrounding refractive index (SRI) with an extremely high sensitivity of 69.769 ± 0.035 μW/RIU and a resolution of 1.433 × 10(-5) ± 8 × 10(-9) RIU between 1.37 and 1.45 RIU. The device provides a large SRI operating range from 1.30 to 1.45 RIU with sufficient discrimination for all individual captured cladding modes. The proposed scheme can be adapted to many different types of bend, temperature, refractive index and other evanescent wave based sensors.

  1. A high-efficiency grating coupler between single-mode fiber and silicon-on-insulator waveguide

    Science.gov (United States)

    Liu, Rongrui; Wang, Yubing; Yin, Dongdong; Ye, Han; Yang, Xiaohong; Han, Qin

    2017-06-01

    We present the design of a diffractive grating structure and get the optimal parameters which can achieve more than 75% coupling efficiency (CE) between single-mode fiber and silicon-on-insulator (SOI) waveguide through 2D finite-different time-domain (FDTD) simulation. The proposed architecture has a uniform structure with no bottom reflection element or silicon overlay. The structure, including grating couplers, adiabatic tapers and interconnection waveguides can be fabricated on the SOI waveguide with only a single electron-beam lithography (ICP) step, which is CMOS-compatible. A relatively high coupling efficiency of 47.2% was obtained at a wavelength of 1562 nm. Project supported by the National Key Research and Development Program of China (No. 2016YFB0402404), the High-Tech Research and Development Program of China (Nos. 2013AA031401, 2015AA016902, 2015AA016904), and the National Natural Foundation of China (Nos. 61674136, 61435002, 61176053, 61274069)

  2. High-efficiency and wideband interlayer grating couplers in multilayer Si/SiO2/SiN platform for 3D integration of optical functionalities.

    Science.gov (United States)

    Sodagar, Majid; Pourabolghasem, Reza; Eftekhar, Ali A; Adibi, Ali

    2014-07-14

    We have designed interlayer grating couplers with single/double metallic reflectors for Si/SiO(2)/SiN multilayer material platform. Out-of-plane diffractive grating couplers separated by 1.6 μm thick buffer SiO(2) layer are vertically stacked against each other in Si and SiN layers. Geometrical optimization using genetic algorithm coupled with electromagnetic simulations using two-dimensional (2D) finite element method (FEM) results in coupler designs with high peak coupling efficiency of up to 89% for double- mirror and 64% for single-mirror structures at telecom wavelength. Also, 3-dB bandwidths of 40 nm and 50 nm are theoretically predicted for the two designs, respectively. We have fabricated the grating coupler structure with single mirror. Measured values for insertion loss and 3-dB bandwidth in the fabricated single-mirror coupler confirms the theoretical results. This opens up the possibility of low-loss 3D dense integration of optical functionalities in hybrid material platforms.

  3. Ultracompact and high efficient silicon-based polarization splitter-rotator using a partially-etched subwavelength grating coupler

    Science.gov (United States)

    Xu, Yin; Xiao, Jinbiao

    2016-06-01

    On-chip polarization manipulation is pivotal for silicon-on-insulator material platform to realize polarization-transparent circuits and polarization-division-multiplexing transmissions, where polarization splitters and rotators are fundamental components. In this work, we propose an ultracompact and high efficient silicon-based polarization splitter-rotator (PSR) using a partially-etched subwavelength grating (SWG) coupler. The proposed PSR consists of a taper-integrated SWG coupler combined with a partially-etched waveguide between the input and output strip waveguides to make the input transverse-electric (TE) mode couple and convert to the output transverse-magnetic (TM) mode at the cross port while the input TM mode confine well in the strip waveguide during propagation and directly output from the bar port with nearly neglected coupling. Moreover, to better separate input polarizations, an additional tapered waveguide extended from the partially-etched waveguide is also added. From results, an ultracompact PSR of only 8.2 μm in length is achieved, which is so far the reported shortest one. The polarization conversion loss and efficiency are 0.12 dB and 98.52%, respectively, together with the crosstalk and reflection loss of -31.41/-22.43 dB and -34.74/-33.13 dB for input TE/TM mode at wavelength of 1.55 μm. These attributes make the present device suitable for constructing on-chip compact photonic integrated circuits with polarization-independence.

  4. On-chip grating coupler array on the SOI platform for fan-in/fan-out of multi-core fibers with low insertion loss and crosstalk

    DEFF Research Database (Denmark)

    Ding, Yunhong; Ye, Feihong; Peucheret, Christophe

    2014-01-01

    We design and fabricate a compact multi-core fiber fan-in/fan-out using a fully-etched grating coupler array on the SOI platform. Lowest coupling loss of 6.8 dB with 3 dB bandwidth of 48 nm and crosstalk lower than ×32 dB are demonstrated.......We design and fabricate a compact multi-core fiber fan-in/fan-out using a fully-etched grating coupler array on the SOI platform. Lowest coupling loss of 6.8 dB with 3 dB bandwidth of 48 nm and crosstalk lower than ×32 dB are demonstrated....

  5. Application of a grating coupler for surface plasmon polariton excitation in a photoemission electron microscopy experiment

    DEFF Research Database (Denmark)

    Leißner, Till; Jauernik, Stephan; Lemke, Christoph;

    of the number of grating ridges and compare the PEEM results with analytic calculations. An increase in the coupling efficiency of > 3 is observed when increasing the number of ridges from 1 to 6. We observe, however, that a further addition of ridges is rather ineffective. This saturation behavior is assigned...... to the grazing incidence excitation geometry intrinsic to a conventional PEEM scheme and the limited propagation distance of the SPP modes at the gold-vacuum interface at the used wavelength....

  6. Broadband grating couplers for efficient thin film solar cells. Final report; Breitband-Gitterkoppler fuer effiziente Duennschichtsolarzellen. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Stutzmann, M.; Nebel, C.E.; Eisele, C.; Klein, S.; Carius, R.; Finger, F.; Schubert, M.

    2002-08-01

    Efficient thin film solar cells usually require a dedicated light trapping strategy in order to achieve an optimum absorption of the solar spectrum. At present, mainly statistically textured transparent conducting electrodes are used for this purpose (TCO layers, e.g. ZnO). One aim of this project was the preparation and characterization of microstructured periodic grating couplers for the efficient trapping of weakly absorbed light in silicon thin film cells. In addition, a preliminary investigation concerning the feasibility of thin SiGe-alloy films on glass as an alternative absorber layer for tandem solar cells was to be performed. Periodically structured TCO electrodes were prepared by holographic laser patterning. These electrode layers are transparent up to the UV spectral range and can be easily structured into sub-micron gratings using HCl etching. In cooperation with the Institute for Photovoltaics (IPV), the resulting light trapping structures were overgrown by amorphous silicon solar cells using PECVD. The electrical and optical properties of these solar cells with integrated grating couplers were investigated in a systematic way, with special emphasis on the possible enhancement of the internal electric field caused by the microstructure. In addition, the growth of amorphous and microcrystalline silicon solar cell structures by hot wire CVD on both, structured as well as unstructured substrates was studied at the IPV. A second part of the project was concerned with the deposition of ultrapure amorphous Si, SiGe, and Ge films on glass by evaporation in an ultra high vacuum, followed by laser recrystallization and hydrogen passivation. For this purpose, a dedicated UHV deposition system was built. The deposited films were recrystallized with a variety of different laser techniques in order to achieve a first optimization of crystallite sizes and electronic properties. Main results of the project: (i) Grating couplers indeed can provide an efficient and

  7. Ultra-low loss fully-etched grating couplers for perfectly vertical coupling compatible with DUV lithography tools

    Science.gov (United States)

    Dabos, G.; Pleros, N.; Tsiokos, D.

    2016-03-01

    Hybrid integration of VCSELs onto silicon-on-insulator (SOI) substrates has emerged as an attractive approach for bridging the gap between cost-effective and energy-efficient directly modulated laser sources and silicon-based PICs by leveraging flip-chip (FC) bonding techniques and silicon grating couplers (GCs). In this context, silicon GCs, should comply with the process requirements imposed by the complimentary-metal-oxide-semiconductor manufacturing tools addressing in parallel the challenges originating from the perfectly vertical incidence. Firstly, fully etched GCs compatible with deep-ultraviolet lithography tools offering high coupling efficiencies are imperatively needed to maintain low fabrication cost. Secondly, GC's tolerance to VCSEL bonding misalignment errors is a prerequisite for practical deployment. Finally, a major challenge originating from the perfectly vertical coupling scheme is the minimization of the direct back-reflection to the VCSEL's outgoing facet which may destabilize its operation. Motivated from the above challenges, we used numerical simulation tools to design an ultra-low loss, bidirectional VCSEL-to-SOI optical coupling scheme for either TE or TM polarization, based on low-cost fully etched GCs with a Si-layer of 340 nm without employing bottom reflectors or optimizing the buried-oxide layer. Comprehensive 2D Finite-Difference-Time- Domain simulations have been performed. The reported GC layout remains fully compatible with the back-end-of-line (BEOL) stack associated with the 3D integration technology exploiting all the inter-metal-dielectric (IMD) layers of the CMOS fab. Simulation results predicted for the first time in fully etched structures a coupling efficiency of as low as -0.87 dB at 1548 nm and -1.47 dB at 1560 nm with a minimum direct back-reflection of -27.4 dB and -14.2 dB for TE and TM polarization, respectively.

  8. An analysis of the surface-normal coupling efficiency of a metal grating coupler embedded in a Scotch tape optical waveguide

    Science.gov (United States)

    Barrios, Carlos Angulo; Canalejas-Tejero, Víctor

    2017-01-01

    The coupling efficiency at normal incidence of recently demonstrated aluminum grating couplers integrated in flexible Scotch tape waveguides has been analyzed theoretically and experimentally. Finite difference time domain (FDTD) and rigorously coupled wave analysis (RCWA) methods have been used to optimize the dimensions (duty cycle and metal thickness) of Scotch tape-embedded 1D Al gratings for maximum coupling at 635 nm wavelength. Good dimension and tape refractive index tolerances are predicted. FDTD simulations reveal the incident beam width and impinging position (alignment) values that avoid rediffraction and thus maximize the coupling efficiency. A 1D Al diffraction grating integrated into a Scotch tape optical waveguide has been fabricated and characterized. The fabrication process, based on pattern transfer, has been optimized to allow complete Al grating transfer onto the Scotch tape waveguide. A maximum coupling efficiency of 20% for TM-polarized normal incidence has been measured, which is in good agreement with the theoretical predictions. The measured coupling efficiency is further increased up to 28% for TM polarization under oblique incidence. Temperature dependence measurements have been also achieved and related to the simulations results and fabrication procedure.

  9. Surface plasmon resonance sensor interrogation with a double-clad fiber coupler and cladding modes excited by a tilted fiber Bragg grating.

    Science.gov (United States)

    Baiad, Mohamad Diaa; Gagné, Mathieu; Madore, Wendy-Julie; De Montigny, Etienne; Godbout, Nicolas; Boudoux, Caroline; Kashyap, Raman

    2013-11-15

    We present a novel optical fiber surface plasmon resonance (SPR) sensor scheme using reflected guided cladding modes captured by a double-clad fiber coupler and excited in a gold-coated fiber with a tilted Bragg grating. This new interrogation approach, based on the reflection spectrum, provides an improvement in the operating range of the device over previous techniques. The device allows detection of SPR in the reflected guided cladding modes and also in the transmitted spectrum, allowing comparison with standard techniques. The sensor has a large operating range from 1.335 to 1.432 RIU, and a sensitivity of 510.5 nm/RIU. The device shows strong dependence on the polarization state of the guided core mode which can be used to turn the SPR on or off.

  10. Preparation Of Planar Optical SiO2-TiO2 And LiNbO3 Waveguides With A Dip Coating Method And An Embossing Technique For Fabricating Grating Couplers And Channel Waveguides

    Science.gov (United States)

    Tiefenthaler, K.; Briguet, V.; Buser, E.; Horisberger, M.; Lukosz, W.

    1983-11-01

    Planar monomode and multimode Si02-Ti02 waveguides were prepared with a dip coating method from Liquicoat solutions supplied by E. MERCK. By varying the Si02:Ti02 mixture ratio the value of the refractive index nF of the waveguiding films on Pyrex glass substrates can be chosen to lie between nF-1.6 and nF =1.36 First results on the preparation of LiNb03 waveguides are also presented. Thicknesses, refractive indices and losses of the waveguides were determined at the blue-green Ar laser wavelengths and at the He-Ne laser wavelengths λ=632.8 nm and λ=1.153 μm. With an embossing technique we fabricated surface relief gratings on Si02-Ti02 wave-guides. We used them successfully as input grating couplers. We propose to use this emboss-ing technique to fabricate channel waveguides and other integrated optical components in inorganic hard waveguiding materials such as Si02-Ti02.

  11. Refractive index engineering of high performance coupler for compact photonic integrated circuits

    Science.gov (United States)

    Liu, Lu; Zhou, Zhiping

    2017-04-01

    High performance couplers are highly desired in many applications, but the design is limited by nearly unchangeable material refractive index. To tackle this issue, refractive index engineering method is investigated, which can be realized by subwavelength grating. Subwavelength gratings are periodical structures with pitches small enough to locally synthesize the refractive index of photonic waveguides, which allows direct control of optical profile as well as easier fabrication process. This review provides an introduction to the basics of subwavelength structures and pay special attention to the design strategies of some representative examples of subwavelength grating devices, including: edge couplers, fiber-chip grating couplers, directional couplers and multimode interference couplers. Benefited from the subwavelength grating which can engineer the refractive index as well as birefringence and dispersion, these devices show better performance when compared to their conventional counterparts.

  12. Wavelength-conserving grating router for intermediate wavelength density

    Science.gov (United States)

    Deri, Robert J.; Patel, Rajesh R.; Bond, Steven W.; Bennett, Cory V.

    2007-03-20

    A wavelength router to be used for fiber optical networking router is based on a diffraction grating which utilizes only N wavelengths to interconnect N inputs to N outputs. The basic approach is to augment the grating with additional couplers or wavelength selective elements so than N-1 of the 2N-1 outputs are combined with other N outputs (leaving only N outputs). One embodiment uses directional couplers as combiners. Another embodiment uses wavelength-selective couplers. Another embodiment uses a pair of diffraction gratings to maintain parallel propagation of all optical beams. Also, beam combining can be implemented either by using retroflection back through the grating pair or by using couplers.

  13. Optical grating coupler biosensor and biomedical applications

    OpenAIRE

    Diéguez Moure, Lorena

    2012-01-01

    Esta tesis consiste en el diseño, fabricación y test de un Biosensor Óptico basado en redes de difracción y sus aplicaciones en biomedicina. Los biosensores ópticos son dispositivos que detectan interacciones biomoleculares específicas mediante un transductor óptico. Exhiben alta sensibilidad, alta estabilidad mecánica, son inmunes a las interferencias electromagnéticas y permiten medidas no destructivas. En los Biosensores Ópticos por Onda Evanescente un modo guiado se propaga a lo larg...

  14. Omnidirectional spin-wave nanograting coupler.

    Science.gov (United States)

    Yu, Haiming; Duerr, G; Huber, R; Bahr, M; Schwarze, T; Brandl, F; Grundler, D

    2013-01-01

    Magnonics as an emerging nanotechnology offers functionalities beyond current semiconductor technology. Spin waves used in cellular nonlinear networks are expected to speed up technologically, demanding tasks such as image processing and speech recognition at low power consumption. However, efficient coupling to microelectronics poses a vital challenge. Previously developed techniques for spin-wave excitation (for example, by using parametric pumping in a cavity) may not allow for the relevant downscaling or provide only individual point-like sources. Here we demonstrate that a grating coupler of periodically nanostructured magnets provokes multidirectional emission of short-wavelength spin waves with giantly enhanced amplitude compared with a bare microwave antenna. Exploring the dependence on ferromagnetic materials, lattice constants and the applied magnetic field, we find the magnonic grating coupler to be more versatile compared with gratings in photonics and plasmonics. Our results allow one to convert, in particular, straight microwave antennas into omnidirectional emitters for short-wavelength spin waves, which are key to cellular nonlinear networks and integrated magnonics.

  15. Analytical and numerical study on grating depth effects in grating coupled waveguide sensors

    DEFF Research Database (Denmark)

    Horvath, R.; Wilcox, L.C.; Pedersen, H.C.;

    2005-01-01

    The in-coupling process for grating-coupled planar optical waveguide sensors is investigated in the case of TE waves. A simple analytical model based on the Rayleigh-Fourier-Kiselev method is applied to take into account the depth of the grating coupler, which is usually neglected in the modeling...

  16. Linear atomic quantum coupler

    CERN Document Server

    El-Orany, Faisal A A

    2009-01-01

    In this paper, we develop the notion of the linear atomic quantum coupler. This device consists of two modes propagating into two waveguides, each of them includes a localized and/or a trapped atom. These waveguides are placed close enough to allow exchanging energy between them via evanescent waves. Each mode interacts with the atom in the same waveguide in the standard way, i.e. as the Jaynes-Cummings model (JCM), and with the atom-mode in the second waveguide via evanescent wave. We present the Hamiltonian for the system and deduce the exact form for the wavefunction. We investigate the atomic inversions and the second-order correlation function. In contrast to the conventional linear coupler, the atomic quantum coupler is able to generate nonclassical effects. The atomic inversions can exhibit long revival-collapse phenomenon as well as subsidiary revivals based on the competition among the switching mechanisms in the system. Finally, under certain conditions, the system can yield the results of the two-m...

  17. Broadband terahertz fiber directional coupler

    DEFF Research Database (Denmark)

    Nielsen, Kristian; Rasmussen, Henrik K.; Jepsen, Peter Uhd

    2010-01-01

    We present the design of a short broadband fiber directional coupler for terahertz (THz) radiation and demonstrate a 3 dB coupler with a bandwidth of 0:6 THz centered at 1:4 THz. The broadband coupling is achieved by mechanically downdoping the cores of a dual-core photonic crystal fiber...

  18. Multimode waveguide based directional coupler

    Science.gov (United States)

    Ahmed, Rajib; Rifat, Ahmmed A.; Sabouri, Aydin; Al-Qattan, Bader; Essa, Khamis; Butt, Haider

    2016-07-01

    The Silicon-on-Insulator (SOI) based platform overcomes limitations of the previous copper and fiber based technologies. Due to its high index difference, SOI waveguide (WG) and directional couplers (DC) are widely used for high speed optical networks and hybrid Electro-Optical inter-connections; TE00-TE01, TE00-TE00 and TM00-TM00 SOI direction couplers are designed with symmetrical and asymmetrical configurations to couple with TE00, TE01 and TM00 in a multi-mode semi-triangular ring-resonator configuration which will be applicable for multi-analyte sensing. Couplers are designed with effective index method and their structural parameters are optimized with consideration to coupler length, wavelength and polarization dependence. Lastly, performance of the couplers are analyzed in terms of cross-talk, mode overlap factor, coupling length and coupling efficiency.

  19. Surface-relief and polarization gratings for solar concentrators.

    Science.gov (United States)

    de Jong, Ties M; de Boer, Dick K G; Bastiaansen, Cees W M

    2011-08-01

    Transmission gratings that combine a large diffraction angle with a high diffraction efficiency and a low angular and wavelength dispersion could be used to collect sunlight in a light guide. In this paper we compare the diffractive properties of polarization gratings and classical surface-relief gratings and explore their possible use in solar concentrators. It is found that polarization gratings and surface-relief gratings have qualitatively comparable diffraction characteristics when their thickness parameters are within the same regime. Relatively large grating periods result in high diffraction efficiencies over a wide range of incident angles. For small grating periods the efficiency and the angular acceptance are decreased. Surface-relief gratings are preferred over polarization gratings as in-couplers for solar concentrators.

  20. Analysis of Nonlinear Directional Couplers

    Institute of Scientific and Technical Information of China (English)

    M. Liu P. Shum; N. Q. Ngo

    2003-01-01

    @@ 1 Introduction Since the coupled-mode theory in cylindrical optical-fiber systems was proposed in 1972, the optical coupling between parallel optical waveguides has been a matter of scientific concern. Two-core fiber couplers, especially, have been studied extensively since the success of producing a two-core fiber functioning as a directional coupler in 1980. The wavelength and polarization selectivity of two-core fibers can find many applications. The nonlinear properties of the two-core fiber coupler were also inspected with the realization of an ultrafast all-optical switch.

  1. Fused-Polished Fiber Couplers

    Institute of Scientific and Technical Information of China (English)

    Sien; Chi; Shiao-Min; Tseng

    2003-01-01

    We report on fused-polished fiber couplers with a new fabrication method. This structure so fabricated is promising while achieving high-performance all-fiber WDM devices. Potential advantages and prospects of our works are presented.

  2. Femtosecond laser fabrication of birefringent directional couplers as polarization beam splitters in fused silica.

    Science.gov (United States)

    Fernandes, Luís A; Grenier, Jason R; Herman, Peter R; Aitchison, J Stewart; Marques, Paulo V S

    2011-06-20

    Integrated polarization beam splitters based on birefringent directional couplers are demonstrated. The devices are fabricated in bulk fused silica glass by femtosecond laser writing (300 fs, 150 nJ at 500 kHz, 522 nm). The birefringence was measured from the spectral splitting of the Bragg grating resonances associated with the vertically and horizontally polarized modes. Polarization splitting directional couplers were designed and demonstrated with 0.5 dB/cm propagation losses and -19 dB and -24 dB extinction ratios for the polarization splitting.

  3. 30 CFR 75.805 - Couplers.

    Science.gov (United States)

    2010-07-01

    ... the ground conductor in the cable. The coupler shall be constructed so that the ground check continuity conductor shall be broken first and the ground conductors shall be broken last when the coupler...

  4. Wireless power transfer magnetic couplers

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Hunter; Gilchrist, Aaron; Sealy, Kylee

    2016-01-19

    A magnetic coupler is disclosed for wireless power transfer systems. A ferrimagnetic component is capable of guiding a magnetic field. A wire coil is wrapped around at least a portion of the ferrimagnetic component. A screen is capable of blocking leakage magnetic fields. The screen may be positioned to cover at least one side of the ferrimagnetic component and the coil. A distance across the screen may be at least six times an air gap distance between the ferrimagnetic component and a receiving magnetic coupler.

  5. Power coupler for the ILC crab cavity

    Energy Technology Data Exchange (ETDEWEB)

    Burt, G.; Dexter, A.; Jenkins, R.; /Lancaster U.; Beard, C.; Goudket, P.; McIntosh, P.A.; /Daresbury; Bellantoni, Leo; /Fermilab

    2007-06-01

    The ILC crab cavity will require the design of an appropriate power coupler. The beam-loading in dipole mode cavities is considerably more variable than accelerating cavities, hence simulations have been performed to establish the required external Q. Simulations of a suitable coupler were then performed and were verified using a normal conducting prototype with variable coupler tips.

  6. The LINAC4 Power Coupler

    CERN Document Server

    Gerigk, F; Montesinos, E; Riffaud, B; Ugena Tirado, P; Wegner, R

    2011-01-01

    Linac4 is employing three types of accelerating structures after the RFQ: a Drift Tube Linac (DTL), a Cell- Coupled DTL (CCDTL), and a Pi-Mode Structure (PIMS) to accelerate the beam up to 160 MeV at 352.2MHz. The structures are designed for a peak power of approximately 1 MW per power coupler, which is transported via rectangular waveguides from the klystron gallery to the RF cavities. The coupler itself consists of two parts: a ceramic window, which separates the cavity vacuum from the air in the waveguides, and a Tuner-adjustablewaveguide Coupler (TaCo), which couples the RF power through an iris to the cavity. In the frame of the Linac4 R&D both devices have been significantly improvedwith respect to their commonly used design. On the coupler side, the waveguide short circuit with its matched length has been replaced by a fixedlength /4 short circuit. The RF matching is done by a simple piston tuner, which allows a quick matching to different cavity quality factors. In the window part, which usually c...

  7. Soliton switching in directional couplers

    NARCIS (Netherlands)

    Valkering, T.P.; Hoekstra, Hugo; de Boer, Pieter-Tjerk

    1999-01-01

    The mechanism of pulse switching is investigated analytically and numerically for a family of initial conditions with a solitonlike pulse in one channel and no signal on the other channel of the coupler. This investigation is performed directly in the coupled nonlinear Schroedinger equations that

  8. Optical dipole mirror for cold atoms based on a metallic diffraction grating

    DEFF Research Database (Denmark)

    Kawalec, Tomasz; Bartoszek-Bober, Dobroslawa; Panas, Roman

    We report on the realization of a plasmonic dipole mirror for cold atoms based on a metallic grating coupler. A cloud of atoms is reflected by the repulsive potential generated by surface plasmon polaritons (SPPs) excited on a reflection gold grating by a 780 nm laser beam. Experimentally...

  9. Optical dipole mirror for cold atoms based on a metallic diffraction grating

    DEFF Research Database (Denmark)

    Kawalec, Tomasz; Bartoszek-Bober, Dobroslawa; Panas, Roman

    2014-01-01

    We report on the realization of a plasmonic dipole mirror for cold atoms based on a metallic grating coupler. A cloud of atoms is reflected by the repulsive potential generated by surface plasmon polaritons (SPPs) excited on a reflection gold grating by a 780 nm laser beam. Experimentally...

  10. Experimental demonstration of ultra-wideband and high-efficiency terahertz spoof surface plasmon polaritons coupler

    Science.gov (United States)

    Tang, Heng-He; Ma, Tian-Jun; Liu, Pu-Kun

    2016-05-01

    Spoof surface plasmon polaritons (SSPPs) are promising for subwavelength waveguiding in the terahertz (THz) frequency range. However, they cannot be efficiently excited from spatial propagating or guided waves due to the mismatched momenta. In this paper, a THz coupler is designed to smoothly bridge SSPPs and guided (or propagating) waves. By using a tapered parallel-plate waveguide, the incident energies are efficiently compressed and coupled into a subwavelength gap. Then, the momenta differences are mitigated with a graded grating. The numerical simulations show that the relative bandwidth of the coupler reaches up to 127%, and the maximum coupling efficiency is 99%. More importantly, experiment results in the 0.22 THz-0.33 THz frequency range are also presented to verify the good performance of the coupler. The work provides a technical support for terahertz waveguiding.

  11. Grating-assisted silicon-on-insulator racetrack resonator reflector.

    Science.gov (United States)

    Boeck, Robert; Caverley, Michael; Chrostowski, Lukas; Jaeger, Nicolas A F

    2015-10-05

    We experimentally demonstrate a grating-assisted silicon-on-insulator (SOI) racetrack resonator reflector with a reflect port suppression of 10.3 dB and no free spectral range. We use contra-directional grating couplers within the coupling regions of the racetrack resonator to enable suppression of all but one of the peaks within the reflect port spectrum as well as all but one of the notches within the through port spectrum.

  12. Field analysis of two-dimensional focusing grating

    NARCIS (Netherlands)

    Borsboom, P.P.; Frankena, H.J.

    1995-01-01

    The method that we have developed [P-P. Borsboom, Ph.D. dissertation (Delft University of Technology, Delft, The Netherlands); P-P. Borsboom and H. J. Frankena, J. Opt. Soc. Am. A 12, 1134–1141 (1995)] is successfully applied to a two-dimensional focusing grating coupler. The field in the focal regi

  13. A linear atomic quantum coupler

    Energy Technology Data Exchange (ETDEWEB)

    El-Orany, Faisal A A [Department of Mathematics and computer Science, Faculty of Science, Suez Canal University 41522, Ismailia (Egypt); Wahiddin, M R B, E-mail: el_orany@hotmail.co, E-mail: faisal.orany@mimos.m, E-mail: mridza@mimos.m [Cyberspace Security Laboratory, MIMOS Berhad, Technology Park Malaysia, 57000 Kuala Lumpur (Malaysia)

    2010-04-28

    In this paper we develop the notion of the linear atomic quantum coupler. This device consists of two modes propagating into two waveguides, each of which includes a localized atom. These waveguides are placed close enough to allow exchange of energy between them via evanescent waves. Each mode interacts with the atom in the same waveguide in the standard way as the Jaynes-Cummings model (JCM) and with the atom-mode system in the second waveguide via the evanescent wave. We present the Hamiltonian for this system and deduce its wavefunction. We investigate the atomic inversions and the second-order correlation function. In contrast to the conventional coupler the atomic quantum coupler is able to generate nonclassical effects. The atomic inversions can exhibit a long revival-collapse phenomenon as well as subsidiary revivals based on the competition among the switching mechanisms in the system. Finally, under certain conditions the system can yield the results of the two-mode JCM.

  14. C-Coupler1: a Chinese community coupler for Earth System Modelling

    Directory of Open Access Journals (Sweden)

    L. Liu

    2014-06-01

    Full Text Available Coupler is a fundamental software tool for Earth System Modelling. Targeting the requirements of 3-D coupling, high-level sharing, common model software platform and better parallel performance, we started to design and develop a community coupler (C-Coupler from 2010 in China, and finished the first version (C-Coupler1 recently. The C-Coupler1 is a parallel 3-D coupler that achieves the same (bit-identical result with any number of processes. Guided by the general design of the C-Coupler, the C-Coupler1 enables various component models and various coupled model versions to be integrated on the same common model software platform to achieve a~higher-level sharing, where the component models and the coupler can keep the same code version in various model versions for simulation. Moreover, it provides the C-Coupler platform, a uniform runtime environment for operating various kinds of model simulations in the same manner. Now the C-Coupler1 is ready for Earth System Modelling, and it is publicly available. In China, there are more and more model groups using the C-Coupler1 for the development and application of models.

  15. Integrated asymmetric vertical coupler pressure sensors

    Science.gov (United States)

    Kiyat, Isa; Kocabas, Askin; Akcag, Imran; Aydinli, Atilla

    2004-08-01

    Design and analysis of a novel pressure sensor based on a silicon-on-insulator asymmetric integrated vertical coupler is presented. The coupler is composed of a single mode low index waveguide and a thin silicon slab. Wavelength selective optical modulation of asymmetric vertical coupler is examined in detail. Its potential for sensing applications is highlighted as an integrated optical pressure sensor which can be realized by standard silicon micro-fabrication. Sensitivity of transmission of such couplers on refractive index change of silicon slab ensures that they are good candidates for applications requiring high sensitivities.

  16. LHC Crab Cavity Coupler Test Boxes

    CERN Document Server

    Mitchell, James; Burt, Graeme; Calaga, Rama; Macpherson, Alick; Montesinos, Eric; Silva, Subashini; Tutte, Adam; Xiao, Binping

    2016-01-01

    The LHC double quarter wave (DQW) crab cavities have two different types of Higher Order Mode (HOM) couplers in addition to a fundamental power coupler (FPC). The FPC requires conditioning, so to achieve this we have designed a radio-frequency (RF) quarter wave resonator to provide high transmission between two opposing FPCs. For the HOM couplers we must ensure that the stop-band filter is positioned at the cavity frequency and that peak transmission occurs at the same frequencies as the strongest HOMs. We have designed two test boxes which preserve the cavity spectral response in order to test the couplers.

  17. RF Power and HOM Coupler Tutorial

    Energy Technology Data Exchange (ETDEWEB)

    Rusnak, B

    2003-10-28

    Radio frequency (RF) couplers are used on superconducting cavities to deliver RF power for creating accelerating fields and to remove unwanted higher-order mode power for reducing emittance growth and cryogenic load. RF couplers in superconducting applications present a number of interdisciplinary design challenges that need to be addressed, since poor performance in these devices can profoundly impact accelerator operations and the overall success of a major facility. This paper will focus on critical design issues for fundamental and higher order mode (HOM) power couplers, highlight a sampling of reliability-related problems observed in couplers, and discuss some design strategies for improving performance.

  18. Integrated Optical Asymmetric Coupler Pressure Sensor

    Science.gov (United States)

    Kiyat, Isa; Kocabas, Coskun; Aydinli, Atilla

    2004-05-01

    Analysis of a novel pressure sensor based on a silicon-on-insulator (SOI) asymmetric vertical coupler is presented. The integrated optical component is a coupler composed of a single mode (SM) low index waveguide and a thin silicon slab. High sensitivities of about 0.14 rad.kPa-1 should be achieved.

  19. High Power Co-Axial Coupler

    Energy Technology Data Exchange (ETDEWEB)

    Neubauer, M. [Muons, Inc.; Dudas, A. [Muons, Inc.; Rimmer, Robert A. [JLAB; Guo, Jiquan [JLAB; Williams, R. Scott [JLAB

    2013-12-01

    A very high power Coax RF Coupler (MW-Level) is very desirable for a number of accelerator and commercial applications. For example, the development of such a coupler operating at 1.5 GHz may permit the construction of a higher-luminosity version of the Electron-Ion Collider (EIC) being planned at JLab. Muons, Inc. is currently funded by a DOE STTR grant to develop a 1.5-GHz high-power doublewindowcoax coupler with JLab (about 150 kW). Excellent progress has been made on this R&D project, so we propose an extension of this development to build a very high power coax coupler (MW level peak power and a max duty factor of about 4%). The dimensions of the current coax coupler will be scaled up to provide higher power capability.

  20. Miniature mechanical transfer optical coupler

    Science.gov (United States)

    Abel, Philip; Watterson, Carl

    2011-02-15

    A miniature mechanical transfer (MT) optical coupler ("MMTOC") for optically connecting a first plurality of optical fibers with at least one other plurality of optical fibers. The MMTOC may comprise a beam splitting element, a plurality of collimating lenses, and a plurality of alignment elements. The MMTOC may optically couple a first plurality of fibers disposed in a plurality of ferrules of a first MT connector with a second plurality of fibers disposed in a plurality of ferrules of a second MT connector and a third plurality of fibers disposed in a plurality of ferrules of a third MT connector. The beam splitting element may allow a portion of each beam of light from the first plurality of fibers to pass through to the second plurality of fibers and simultaneously reflect another portion of each beam of light from the first plurality of fibers to the third plurality of fibers.

  1. Overview of recent HOM coupler development

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, B. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-09-13

    Higher Order Mode (HOM) damping is important for SRF applications, especially for high-intensity machines. A good HOM damping design will help to reduce power load to the cryogenic system and to reduce the risk of beam breakup. The design of HOM damping, including antenna/loop HOM couplers, beam pipe HOM absorbers and waveguide HOM couplers, is to solve a multi-physics problem that involves RF, thermal, mechanical, and beam-cavity interaction issues. In this talk, the author provides an overview on the latest advances of the HOM couplers for high-intensity SRF applications.

  2. Vacuum fiber-fiber coupler

    Science.gov (United States)

    Heinrici, Axel; Bjelajac, Goran; Jonkers, Jeroen; Jakobs, Stefan; Olschok, Simon; Reisgen, Uwe

    2017-02-01

    Research and development carried out by the ISF Welding and Joining Institute of RWTH Aachen University has proven that combining high power laser and low vacuum atmosphere provides a welding performance and quality, which is comparable to electron beam welding. The developed welding machines are still using a beam forming which takes place outside the vacuum and the focusing laser beam has to be introduced to the vacuum via a suitable window. This inflexible design spoils much of the flexibility of modern laser welding. With the target to bring a compact, lightweight flying optics with flexible laser transport fibers into vacuum chambers, a high power fiber-fiber coupler has been adapted by II-VI HIGHYAG that includes a reliable vacuum interface. The vacuum-fiber-fiber coupler (V-FFC) is tested with up to 16 kW sustained laser power and the design is flexible in terms of a wide variety of laser fiber plug systems and vacuum flanges. All that is needed to implement the V-FFC towards an existing or planned vacuum chamber is an aperture of at least 100 mm (4 inch) diameter with any type of vacuum or pressure flange. The V-FFC has a state-of-the-art safety interface which allows for fast fiber breakage detection for both fibers (as supported by fibers) by electric wire breakage and short circuit detection. Moreover, the System also provides connectors for cooling and electric signals for the laser beam optics inside the vacuum. The V-FFC has all necessary adjustment options for coupling the laser radiation to the receiving fiber.

  3. PALM: a Parallel Dynamic Coupler

    Science.gov (United States)

    Thevenin, A.; Morel, T.

    2008-12-01

    In order to efficiently represent complex systems, numerical modeling has to rely on many physical models at a time: an ocean model coupled with an atmospheric model is at the basis of climate modeling. The continuity of the solution is granted only if these models can constantly exchange information. PALM is a coupler allowing the concurrent execution and the intercommunication of programs not having been especially designed for that. With PALM, the dynamic coupling approach is introduced: a coupled component can be launched and can release computers' resources upon termination at any moment during the simulation. In order to exploit as much as possible computers' possibilities, the PALM coupler handles two levels of parallelism. The first level concerns the components themselves. While managing the resources, PALM allocates the number of processes which are necessary to any coupled component. These models can be parallel programs based on domain decomposition with MPI or applications multithreaded with OpenMP. The second level of parallelism is a task parallelism: one can define a coupling algorithm allowing two or more programs to be executed in parallel. PALM applications are implemented via a Graphical User Interface called PrePALM. In this GUI, the programmer initially defines the coupling algorithm then he describes the actual communications between the models. PALM offers a very high flexibility for testing different coupling techniques and for reaching the best load balance in a high performance computer. The transformation of computational independent code is almost straightforward. The other qualities of PALM are its easy set-up, its flexibility, its performances, the simple updates and evolutions of the coupled application and the many side services and functions that it offers.

  4. Grating Loaded Cantilevers for Displacement Measurements

    Science.gov (United States)

    Karademir, Ertugrul; Olcum, Selim; Atalar, Abdullah; Aydinli, Atilla

    2010-03-01

    A cantilever with a grating coupler engraved on its tip is used for measuring displacement. The coupled light in the cantilever is guided to a single mode optical waveguide defined at the base of the cantilever. The grating period is 550 nm and is fabricated on a SOI wafer using nanoimprint lithography. The waveguide and the cantilever are defined by an RIE and cantilevers released by KOH and HF solutions. Light with 1550 nm wavelength, is directed onto the grating coupler and detected at the cleaved end of the SOI waveguide. The angle of incidence is controlled by a motorized rotary stage. Light couples into the waveguide at a characteristic angle with a full width at half maximum of approximately 6.9 mrads translating into a Q factor of 87.5. The displacement sensitivity is measured by driving the cantilever with a frequency controlled piezoelectric element. The modulation of the light at the waveguide output is lock-in detected by a biased infrared detector. The resulting 43%mrad-1 sensitivity can be increased with further optimization.

  5. A Tandem Coupler for Terahertz Integrated Circuits

    Science.gov (United States)

    Reck, Theodore J.; Deal, William; Chattopadhyay, Goutam

    2013-01-01

    A coplanar waveguide 3 dB quadrature coupler operating from 500 to 700 GHz is designed, fabricated and measured. On-wafer measurements demonstrate an amplitude balance of +/-2 dB and phase balance of +/-20 deg.

  6. Wide wavelength-tuning of a double-clad Yb3+-doped fiber laser based on a fiber Bragg grating array

    NARCIS (Netherlands)

    Alvarez-Chavez, J.A.; Martinez-Rios, A.; Torres-Gomez, I.; Offerhaus, H.L.

    2007-01-01

    We report wide wavelength tuning in a double-clad ytterbium-doped fiber laser. The laser cavity consists of an array of broadband high-reflection fiber Bragg gratings and a bulk grating as output coupler and wavelength selection element. The proposed fiber laser configuration combines low intra-cavi

  7. An ultrafast nanotip electron gun triggered by grating-coupled surface plasmons

    Science.gov (United States)

    Schröder, Benjamin; Sivis, Murat; Bormann, Reiner; Schäfer, Sascha; Ropers, Claus

    2015-12-01

    We demonstrate multiphoton photoelectron emission from gold nanotips induced by nanofocusing surface plasmons, resonantly excited on the tip shaft by a grating coupler. The tip is integrated into an electron gun assembly, which facilitates control over the spatial emission sites and allows us to disentangle direct grating emission from plasmon-triggered apex emission. The nanoscale source size of this electron gun concept enables highly coherent electron pulses with applications in ultrafast electron imaging and diffraction.

  8. An ultrafast nanotip electron gun triggered by grating-coupled surface plasmons

    Energy Technology Data Exchange (ETDEWEB)

    Schröder, Benjamin; Sivis, Murat; Bormann, Reiner; Schäfer, Sascha; Ropers, Claus, E-mail: cropers@gwdg.de [4th Physical Institute - Solids and Nanostructures, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen (Germany)

    2015-12-07

    We demonstrate multiphoton photoelectron emission from gold nanotips induced by nanofocusing surface plasmons, resonantly excited on the tip shaft by a grating coupler. The tip is integrated into an electron gun assembly, which facilitates control over the spatial emission sites and allows us to disentangle direct grating emission from plasmon-triggered apex emission. The nanoscale source size of this electron gun concept enables highly coherent electron pulses with applications in ultrafast electron imaging and diffraction.

  9. Field analysis of two-dimensional focusing grating

    OpenAIRE

    Borsboom, P.P.; Frankena, H.J.

    1995-01-01

    The method that we have developed [P-P. Borsboom, Ph.D. dissertation (Delft University of Technology, Delft, The Netherlands); P-P. Borsboom and H. J. Frankena, J. Opt. Soc. Am. A 12, 1134–1141 (1995)] is successfully applied to a two-dimensional focusing grating coupler. The field in the focal region has been determined for symmetrical chirped gratings consisting of as many as 124 corrugations. The intensity distribution in the focal region agrees well with the approximate predictions of geo...

  10. Coupler induced monopole component and its minimization in deflecting cavities

    Directory of Open Access Journals (Sweden)

    P. K. Ambattu

    2013-06-01

    Full Text Available Deflecting cavities are used in particle accelerators for the manipulation of charged particles by deflecting or crabbing (rotating them. For short deflectors, the effect of the power coupler on the deflecting field can become significant. The particular power coupler type can introduce multipole rf field components and coupler-specific wakefields. Coupler types that would normally be considered like standard on-cell coupler, waveguide coupler, or mode-launcher coupler could have one or two rf feeds. The major advantage of a dual-feed coupler is the absence of monopole and quadrupole rf field components in the deflecting structure. However, a dual-feed coupler is mechanically more complex than a typical single-feed coupler and needs a splitter. For most applications, deflecting structures are placed in regions where there is small space hence reducing the size of the structure is very desirable. This paper investigates the multipole field components of the deflecting mode in single-feed couplers and ways to overcome the effect of the monopole component on the beam. Significant advances in performance have been demonstrated. Additionally, a novel coupler design is introduced which has no monopole field component to the deflecting mode and is more compact than the conventional dual-feed coupler.

  11. Optical dipole mirror for cold atoms based on a metallic diffraction grating

    DEFF Research Database (Denmark)

    Kawalec, Tomasz; Bartoszek-Bober, Dobroslawa; Panas, Roman

    2014-01-01

    and numerically determined mirror efficiencies are close to 100%. The intensity of SPPs above a real grating coupler and the atomic trajectories, as well as the momentum dispersion of the atom cloud being reflected, are computed. A suggestion is given as to how the plasmonic mirror might serve as an optical atom...

  12. High power couplers for Project X

    Energy Technology Data Exchange (ETDEWEB)

    Kazakov, S.; Champion, M.S.; Yakovlev, V.P.; Kramp, M.; Pronitchev, O.; Orlov, Y.; /Fermilab

    2011-03-01

    Project X, a multi-megawatt proton source under development at Fermi National Accelerator Laboratory. The key element of the project is a superconducting (SC) 3GV continuous wave (CW) proton linac. The linac includes 5 types of SC accelerating cavities of two frequencies.(325 and 650MHz) The cavities consume up to 30 kW average RF power and need proper main couplers. Requirements and approach to the coupler design are discussed in the report. New cost effective schemes are described. Results of electrodynamics and thermal simulations are presented.

  13. Coupler design for an L-band electron linac

    Institute of Scientific and Technical Information of China (English)

    ZHAO Wei; TANG Xiao; SHI Rong-Jian; HOU Mi

    2012-01-01

    The RF coupler is a key component for an accelerating structure which is the most important component for a linac.In order to feed microwave power into the accelerating cavities effectively,the coupler has to be well matched with the feeding waveguide.In this paper,an electron linac coupler was designed,constructed and tested.A numerical simulation method based on the Kyhl's method was employed to search for the optimal dimensions of the coupler.The frequency and the coupling coefficient as a function of the coupler dimensions were also calculated.The results fitted the Kyhl's method simulation results well and gave tolerances of the coupler.The coupler was brazed to the accelerating cavities and it was cold-tested and hot-tested.The experimental results were consistent with the numerical simulation results.

  14. Transverse emittance dilution due to coupler kicks in linear accelerators

    Directory of Open Access Journals (Sweden)

    Brandon Buckley

    2007-11-01

    Full Text Available One of the main concerns in the design of low emittance linear accelerators (linacs is the preservation of beam emittance. Here we discuss one possible source of emittance dilution, the coupler kick, due to transverse electromagnetic fields in the accelerating cavities of the linac caused by the power coupler geometry. In addition to emittance growth, the coupler kick also produces orbit distortions. It is common wisdom that emittance growth from coupler kicks can be strongly reduced by using two couplers per cavity mounted opposite each other or by having the couplers of successive cavities alternate from above to below the beam pipe so as to cancel each individual kick. While this is correct, including two couplers per cavity or alternating the coupler location requires large technical changes and increased cost for superconducting cryomodules where cryogenic pipes are arranged parallel to a string of several cavities. We therefore analyze consequences of alternate coupler placements. We show here that alternating the coupler location from above to below compensates the emittance growth as well as the orbit distortions. For sufficiently large Q values, alternating the coupler location from before to after the cavity leads to a cancellation of the orbit distortion but not of the emittance growth, whereas alternating the coupler location from before and above to behind and below the cavity cancels the emittance growth but not the orbit distortion. We show that cancellations hold for sufficiently large Q values. These compensations hold even when each cavity is individually detuned, e.g., by microphonics. Another effective method for reducing coupler kicks that is studied is the optimization of the phase of the coupler kick so as to minimize the effects on emittance from each coupler. This technique is independent of the coupler geometry but relies on operating on crest. A final technique studied is symmetrization of the cavity geometry in the

  15. Structural Analysis of Taper-Threaded Rebar Couplers

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Seok Jae [Univ. of Ulsan, Ulsan (Korea, Republic of); Kwon, Hyuk Mo; Seo, Sang Hwan [Sammi Precision Co. Ltd., Ulsan (Korea, Republic of)

    2014-05-15

    A number of rebar couplers were developed by the leading companies. The information about the products is available from the company website. However, the theory on the taper-threaded coupler is not available. In this paper, the mechanics of the taper-thread was developed to understand the effect of the tightening torque. Structural analysis of our own newly developed rebar coupler was done to improve the strength of the coupler. The taper-threaded rebar coupler was analyzed. The tightening of the rebar into the coupler developed a circumferential stress in the coupler. The circumferential stress depends on the coefficient of friction as well as the tightening torque. The circumferential stress is less than the allowable stress 20 kgf/mm{sup 2} of the material for the coefficient of friction greater than 0.1. The tightening of the rebar into the coupler and the subsequent tensioning was simulated using CATIA. Linear elastic analysis considering contact was done. The tightening of the taper-threaded rebar developed a uniform stress distribution in both standard coupler and position coupler. On the other hand, the tightening of the nut in the axial direction developed a non-uniform stress distribution. Similarly the tensioning also developed a non-uniform stress distribution.

  16. Single-mode fiber linearly tapered planar waveguide tunable coupler

    Science.gov (United States)

    Das, Alok K.; Hussain, Anwar

    1997-09-01

    We developed a simple system of tunable fiber film coupler using a linearly tapered thin-film planar waveguide (PWG) evanescently coupled by a single-mode distributed fiber half-coupler. We investigate the characteristics of the coupler theoretically and experimentally taking into consideration the refractive index ( n f ) of nonuniform films, the magnitude of nonuniformity ( m ) of the films, and the source wavelength ( ). The thickness variation of the nonuniform film is along the direction of propagation of optical power. Tapered and plano concave thin films of a mix of oils as well as a plano concave poly(methyl methacrylate) film were fabricated to serve as nonuniform PWG s. Similar to single-mode fiber with a uniform thickness PWG coupler, such a coupler also provides light modulation with a change of n f . However, position shifting of a half-coupler in a tapered PWG structure along the direction of propagation exhibits the variation of fiber throughput power. This action serves as a simple system for a tunable fiber film coupler. Wavelength-dependent throughput fiber power for such a coupler also behaves as a filter. The center wavelength can be controlled by shifting the position of the half-coupler. A coupling fiber as a half-coupler can be used for efficient coupling. We performed a theoretical analysis of the structure using Marcuse s model and observed good agreement with the experimental results.

  17. Coupler rotation behaviour and its effect on heavy haul trains

    Science.gov (United States)

    Xu, Z. Q.; Ma, W. H.; Wu, Q.; Luo, S. H.

    2013-12-01

    When a locomotive coupler rotates at an angle, the lateral component of the coupler force has an adverse effect on the locomotive's safety, particularly in heavy haul trains. In this paper, a model of a head-mid configuration, a 20,000-t heavy haul train is developed to analyse the rotation behaviour of the locomotive's coupler system and its effect on the dynamic behaviour of such a train's middle locomotive when operating on tangent and curved tracks. The train model includes detailed coupler and draft gear with which to consider the hysteretic characteristics of the rubber draft gear model, the friction characteristics of the coupler knuckles, and the alignment-control characteristics of the coupler shoulder. The results indicate that the coupler's rotation behaviour differs between the tangent and curved tracks, significantly affecting the locomotive's running performance under the braking condition. A larger coupler rotation angle generates a larger lateral component, which increases the wheelset's lateral force and the derailment coefficient. Decreasing the maximum coupler free angle can improve the locomotive's operational performance and safety. Based on these results, the recommended maximum coupler free angle is 4°.

  18. HOM Couplers for CERN SPL Cavities

    CERN Document Server

    Papke, Kai; Van Rienen, U

    2013-01-01

    Higher-Order-Modes (HOMs) may affect beam stability and refrigeration requirements of superconducting proton linacs such as the SPL, which is studied at CERN as the driver for future neutrino facilities. In order to limit beam-induced HOM effects, CERN considers the use of HOM couplers on the cut-off tubes of the 5-cell superconducting cavities. These couplers consist of resonant antennas shaped as loops or probes, which are designed to couple to modes of a specific frequency range. In this paper the design process is presented and a comparison is made between various design options for the medium and high-beta SPL cavities, both operating at 704.4 MHz. The RF characteristics and thermal behaviour of the various designs are discussed.

  19. Optical gears in a nanophotonic directional coupler

    CERN Document Server

    Zhang, Fengchun; Zhang, Heran; Zhang, Yong; Huang, Xu-Guang; Jia, Baohua; Liu, Songhao

    2016-01-01

    Gears are rotating machines, meshing with each other by teeth to transmit torque. Interestingly, the rotating directions of two meshing gears are opposite, clockwise and counterclockwise. Although this opposite handedness motion has been widely investigated in machinery science, the analogue behavior of photons remains undiscovered. Here, we present a simple nanophotonic directional coupler structure which can generate two meshing gears of angular momentum (AM) of light, optical gears. Due to the abrupt phase shift effect and birefringence effect, the AM states of photons vary with the propagation distance in two adjacent waveguides of the coupler. Thus, by the choice of coupling length, it is able to obtain two light beams with opposite handedness of AM, confirming the appearance of optical gears. The full control in the handedness of output beams is achieved via tuning the relative phase between two orthogonal modes at the input ports. Optical gears thus offer the possibility of exploring light-matter inter...

  20. MICROSTRIP COUPLER DESIGN USING BAT ALGORITHM

    Directory of Open Access Journals (Sweden)

    EzgiDeniz Ulker

    2014-01-01

    Full Text Available Evolutionary and swarm algorithms have found many applications in design problems since todays computing power enables these algorithms to find solutions to complicated design problems very fast. Newly proposed hybridalgorithm, bat algorithm, has been applied for the design of microwave microstrip couplers for the first time. Simulation results indicate that the bat algorithm is a very fast algorithm and it produces very reliable results.

  1. Mid-IR fused fiber couplers

    Science.gov (United States)

    Stevens, G.; Woodbridge, T.

    2016-03-01

    We present results from our recent efforts on developing single-mode fused couplers in ZBLAN fibre. We have developed a custom fusion workstation for working with lower melting temperature fibres, such as ZBLAN and chalcogenide fibres. Our workstation uses a precisely controlled electrical heater designed to operate at temperatures between 100 - 250°C as our heat source. The heated region of the fibers was also placed in an inert atmosphere to avoid the formation of microcrystal inclusions during fusion. We firstly developed a process for pulling adiabatic tapers in 6/125 μm ZBLAN fibre. The tapers were measured actively during manufacture using a 2000 nm source. The process was automated so that the heater temperature and motor speed automatically adjusted to pull the taper at constant tension. This process was then further developed so that we could fuse and draw two parallel 6/125 μm ZBLAN fibres, forming a single-mode coupler. Low ratio couplers (1-10%) that could be used as power monitors were manufactured that had an excess loss of 0.76 dB. We have also manufactured 50/50 splitters and wavelength division multiplexers (WDMs). However, the excess loss of these devices was typically 2 - 3 dB. The increased losses were due to localised necking and surface defects forming as the tapers were pulled further to achieve a greater coupling ratio. Initial experiments with chalcogenide fibre have shown that our process can be readily adapted for chalcogenide fibres. A 5% coupler with 1.5 dB insertion loss was manufactured using commercial of the shelf (COTS) fibres.

  2. Low Cost Star Couplers For Automotive Applications

    Science.gov (United States)

    Sriram, S.; Boiarski, A. A.

    1989-02-01

    Within the next 5 to 10 years optical fibers are expected to be used in automobile local area networks. For this application, both glass and plastic fibers have the potential to play a significant role. Under the hood, where the operating temperatures tend to be too high for plastic fibers, glass based fibers are likely to be used. Glass based fibers are also intended for use in fiber optic sensors, for example, in engine control systems. However, in general, the preferred fiber material is plastic due to economic considerations. In the case of optical fibers for a network within the passenger compartment, plastic optical fibers are adequate and several prototype systems have already been built and demonstrated. The principal reasons for considering the use of optical fibers are discussed in several papers (1-3). A key component in an optical fiber network is a star coupler. This paper will deal with the fabrication and test results of a prototype 7x7 transmissive star coupler developed at Battelle. The optical fiber diameter chosen for the development of the star coupler is a 1 mm diameter fiber manufactured by Mitsubishi (ESKA-40). Currently both 750 and 1000 micron diameter fibers are under consideration for the automobile but the technology reported here is capable of accommodating either fiber. The final choice of the fiber type will depend on several economic factors which are yet unknown.

  3. Sub-wavelength grating structure on the planar waveguide (Conference Presentation)

    Science.gov (United States)

    Qing-Song, Zhu; Sheng-Hui, Chen

    2016-10-01

    Making progress in recent years, with the technology of the grating, the grating period can be reduced to shrink the size of the light coupler on a waveguide. The working wavelength of the light coupler can be in the range from the near-infrared to visible. In this study , we used E-gun evaporation system with ion-beam-assisted deposition system to fabricate bottom cladding (SiO2), guiding layer (Ta2O5) and Distributed Bragg Reflector(DBR) of the waveguide on the silicon substrate. Electron-beam lithography is used to make sub-wavelength gratings and reflector grating on the planar waveguide which is a coupling device on the guiding layer. The best fabrication parameters were analyzed to deposit the film. The exposure and development times also influenced to fabricate the grating quality. The purpose is to reduce the device size and enhance coupling efficiency which maintain normal incidence of the light . We designed and developed the device using the Finite-Difference Time-Domain (FDTD) method. The grating period, depth, fill factor, film thickness, Distributed Bragg Reflector(DBR) numbers and reflector grating period have been discussed to enhance coupling efficiency and maintained normal incidence of the light. According to the simulation results, when the wavelength is 1300 nm, the coupling grating period is 720 nm and the Ta2O5 film is 460 nm with 360 nm of reflector grating period and 2 layers of Distributed Bragg Reflector, which had the optimum coupling efficiency and normal incidence angle. In the measurement, We successfully measured the TE wave coupling efficiency of the photoresist grating coupling device.

  4. RF Processing of the Couplers for the SNS Superconducting Cavities

    Energy Technology Data Exchange (ETDEWEB)

    Y.Kang; I.E. Campisi; D. Stout; A. Vassioutchenko; M. Stirbet; M. Drury; T. Powers

    2005-07-10

    All eighty-one fundamental power couplers for the 805 MHz superconducting cavities of the SNS linac have been RF conditioned and installed in the cryomodules successfully. The couplers were RF processed at JLAB or at the SNS in ORNL: more than forty couplers have been RF conditioned in the SNS RF Test Facility (RFTF) after the first forty couplers were conditioned at JLAB. The couplers were conditioned up to 650 kW forward power at 8% duty cycle in traveling and standing waves. They were installed on the cavities in the cryomodules and then assembled with the airside waveguide transitions. The couplers have been high power RF tested with satisfactory accelerating field gradients in the cooled cavities.

  5. Silica-on-silicon optical couplers and coupler based optical filters

    DEFF Research Database (Denmark)

    Leick, Lasse

    2002-01-01

    This work concerns modeling and chracterization of non ampligying silica-on-silicon optical components for wavelength division mulitplexed networks. Emphasis is placed on optical couplers and how they can be used as building blocks for devices with a larger complexity. It has been investigated how...... mode interference couplers have superior proces tolerance. The measured characteristics of mulit mode interference couplers deviate from the simulations, showing an unexpected imbalance and large polarization sensitivity. This can be explained by a sligthly non-uniform index distribution across...... penalty. The dispersion can be removed by adding a three-stage all-pass filter on the input arm. The above mentioned silica-on-silicon components have been fabricated using a conventional method where the waveguides are defined and fabricated using cleanroom processing. Waveguides can also be fabricated...

  6. Coaxial HOM coupler for the 500 MHz RF damped cavity

    CERN Document Server

    Koseki, T; Takahashi, T; Kamiya, Yu; Satoh, K; Ogata, H

    2001-01-01

    We have developed a new higher-order modes (HOMs) coupler of coaxial waveguide type for the 500 MHz damped cavity. An SiC ceramics is adopted as microwave absorber. Two prototype models of the HOM coupler have been fabricated and tested. The detailed design of the coupler is described in this paper. The results of RF characteristics measurement and high power conditioning are also presented.

  7. Optimization of unipolar magnetic couplers for EV wireless power chargers

    Science.gov (United States)

    Zeng, H.; Liu, Z. Z.; Chen, H. X.; Zhou, B.; Hei, T.

    2016-08-01

    In order to improve the coupling coefficient of EV wireless power chargers, it's important to optimize the magnetic couplers. To improve the coupling coefficient, the relationship between coupling coefficient and efficiency is derived, and the expression of coupling coefficient based on magnetic circuit is deduced, which provide the basis for optimizing the couplers. By 3D FEM simulation, the optimal core structure and coils are designed for unipolar circular couplers. Experiments are designed to verify the correctness of the optimization results, and compared with previous coupler, the transmission efficiency is improved and weight is reduced.

  8. Crosstalk comparison of lattice-form optical interleaver with different coupler structures

    Science.gov (United States)

    Wan, Zhujun; Luo, Fengguang; Luo, Zhixiang

    2009-05-01

    Lattice circuit made from a cascade of couplers and delay-lines is a popular approach for optical interleaver based on planar lightwave circuit (PLC) technology. Different coupler structures can be employed in the lattice circuit, including 1-stage directional couplers (DCs), 4-stage DCs, and 2-stage multimode interference (MMI) couplers. We fabricated optical interleavers with above three coupler structures, respectively. The experimental results prove that the latter two coupler structures can help to reduce crosstalk, which meets the simulation results well.

  9. Optical Fiber Bragg Grating Michelson Interferometer

    Institute of Scientific and Technical Information of China (English)

    JIANG Yi; JIANG Tian-fu; LIU Li

    2006-01-01

    A new Michelson interferometer based on fiber Bragg grating(FBG) is demonstrated. FBGs are used as reflectors, and the laser is replaced by a broadband source as input light in this interferometer. To demodulate the signals, a 3×3 coupler is used as a splitter. By combining with software demodulation, the outer inter ference can be obtained from the outputs of the interferometer. This kind of in terferometer can also be wavelength-multiplexed easily by composing a series Michelson interferometer. The experiment results show that the clear interference fringe can be obtained by adjusting the path difference to make it less than interference length of FBG. The signals are also demodulated.

  10. Conceptual SPL RF Main Power Coupler design

    CERN Document Server

    Montesinos, Eric

    2011-01-01

    While the upgrade plans of the LHC injectors had to be reduced in scope in 2010, the Superconducting Proton Linac (SPL) remains a fundamental element of plans for a possible future neutrino facility. Prototyping work is therefore continuing at CERN and the current focus is on the test of a first four cavity SPL-like cryomodule with full power. This report summarizes the parameters for the Main Power Coupler design as discussed and approved within the ‘Review of SPL RF power couplers’, held at CERN in March 2010.

  11. Acoustic Coupler for the Acquisition of Coronary Artery Murmurs

    DEFF Research Database (Denmark)

    Zimmermann, Niels Henrik; Schmidt, Samuel; Hansen, John

    The weak murmurs originating from stenosis in the coronary arteries can only be acquired with a dedicated coupler and system design. The aim of the study was to design and evaluate such a coupler. The suggested design is based on the use of a high quality microphone, coupled to the chest through...... that the sensor is suitable for recording of coronary murmurs....

  12. Zeno effect and switching of solitons in nonlinear couplers

    DEFF Research Database (Denmark)

    Abdullaev, F Kh; Konotop, V V; Ögren, Magnus;

    2011-01-01

    The Zeno effect is investigated for soliton type pulses in a nonlinear directional coupler with dissipation. The effect consists in increase of the coupler transparency with increase of the dissipative losses in one of the arms. It is shown that localized dissipation can lead to switching...

  13. Design of shape memory alloy pipe couplers: modeling and experiments

    Science.gov (United States)

    Tabesh, Majid; Atli, Kadri C.; Rohmer, John; Franco, Brian E.; Karaman, Ibrahim; Boyd, James G.; Lagoudas, Dimitris C.

    2012-04-01

    Shape memory alloy (SMA) pipe couplers use the shape memory effect to apply a contact pressure onto the surface of the pipes to be coupled. In the current research, a SMA pipe coupler is designed, fabricated and tested. The thermally induced contact pressure depends on several factors such as the dimensions and properties of the coupler-pipe system. Two alloy systems are considered: commercially-available NiTiNb couplers and in-house developed NiTi couplers. The coupling pressure is measured using strain gages mounted on the internal surface of an elastic ring. An axisymmetric finite element model including SMA constitutive equations is also developed, and the finite element results are compared with the experimental results.

  14. Cost effective all-optical fractional OFDM receiver using an arrayed waveguide grating

    Science.gov (United States)

    Nagashima, T.; Cincotti, G.; Murakawa, T.; Shimizu, S.; Hasegawa, M.; Hattori, K.; Okuno, M.; Mino, S.; Himeno, A.; Wada, N.; Uenohara, H.; Konishi, T.

    2016-12-01

    We experimentally demonstrate the feasibility of implementing a cost effective all-optical fractional orthogonal frequency division multiplexing (AO-FrOFDM) receiver using an arrayed waveguide grating (AWG). The all-optical fractional Fourier transform at the receiver is implemented by modifying the second slab coupler from a conventional all-optical discrete Fourier transform AWG. The open eye diagrams obtained from the experimental results indicate that 12 × 10 Gbit/s DBPSK AO-FrOFDM signals were successfully demultiplexed.

  15. All-reflective Michelson, Sagnac, and Fabry-Perot interferometers based on grating beam splitters.

    Science.gov (United States)

    Sun, K X; Byer, R L

    1998-04-15

    All-reflective Michelson, Sagnac, and Fabry-Perot interferometers based on grating beam splitters are experimentally demonstrated at a wavelength of 1064 nm. A 1200-groove/mm grating diffracting 0 and -1 orders with an efficiency of 48.2% for each order was used as a near-50/50 beam splitter. The all-reflective Sagnac and Michelson interferometers were formed by reintroducing both of the diffracted beams back to the grating. The Fabry-Perot interferometer was formed in a Littrow configuration by using a 1700-groove/mm grating with a blazing efficiency of 91% as a cavity coupler. These interferometers encompass all the fundamental configurations of all-reflective laser interferometric gravitational-wave detectors, promising improved wave-front quality by avoiding volume thermal effects in transmissive optics under high-power laser illumination.

  16. Design of a Label-Free, Distributed Bragg Grating Resonator Based Dielectric Waveguide Biosensor

    Directory of Open Access Journals (Sweden)

    Florian Kehl

    2015-01-01

    Full Text Available In this work, we present a resonant, dielectric waveguide device based on distributed Bragg gratings for label-free biosensing applications. The refractive index sensitive optical transducer aims at improving the performance of planar waveguide grating sensor systems with limited Q-factor and dynamic range by combing the advantages of resonant cavities, such as a multitude of resonance peaks with high finesse, with the manageable complexity of waveguide grating couplers. The general sensor concept is introduced and supported by theoretical considerations as well as numerical simulations based on Coupled Mode Theory. In contrast to a single Bragg grating reflector, the presented Fabry-Pérot type distributed Bragg resonator exhibits an extended measurement range as well as relaxed fabrication tolerances. The resulting, relatively simple sensor structure can be fabricated with standard lithographic means and is independent of expensive light-sources and/or detectors, making an affordable but sensitive device, potentially suitable for point-of-care applications.

  17. A flat microwave photonic filter based on M-Z modulatorand fiber Bragg grating

    Institute of Scientific and Technical Information of China (English)

    QI Chun-hui; PEI Li; NING Ti-gang; GUO Lan; WU Shu-qiang; ZHAO Rui-feng; RUAN Yi

    2009-01-01

    A new multiple-taps and flat microwave photonic filter, which is composed of fiber Bragg grating, M-Z modulator and erbium-doped fiber, is put forward. The flat band-pass or flat band-stop response can be realized by adjusting the coupler's factor and the reflectivity of the fiber Bragg grating or the gain of the erbium-doped fiber. The free spectral range of the filter can be tuned by controlling the length of the erbium-doped fiber. The potential and feasibility of the proposed filtering structures have been demonstrated by simulation.

  18. High temperature superconducting axial field magnetic coupler: realization and test

    Science.gov (United States)

    Belguerras, L.; Mezani, S.; Lubin, T.; Lévêque, J.; Rezzoug, A.

    2015-09-01

    Contactless torque transmission through a large airgap is required in some industrial applications in which hermetic isolation is necessary. This torque transmission usually uses magnetic couplers, whose dimension strongly depends on the airgap flux density. The use of high temperature superconducting (HTS) coils to create a strong magnetic field may constitute a solution to reduce the size of the coupler. It is also possible to use this coupler to replace a torque tube in transmitting the torque produced by a HTS motor to its load. This paper presents the detailed construction and tests of an axial field HTS magnetic coupler. Pancake coils have been manufactured from BSCCO tape and used in one rotor of the coupler. The second rotor is mainly composed of NdFeB permanent magnets. Several tests have been carried out showing that the constructed coupler is working properly. A 3D finite element (FE) model of the studied coupler has been developed. Airgap magnetic field and torque measurements have been carried out and compared to the FE results. It has been shown that the measured and the computed quantities are in satisfactory agreement.

  19. An RF input coupler for a superconducting single cell cavity

    Energy Technology Data Exchange (ETDEWEB)

    Fechner, B.; Ouchi, Nobuo; Kusano, Joichi; Mizumoto, Motoharu; Mukugi, Ken [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Krawczyk, F.

    1999-03-01

    Japan Atomic Energy Research Institute proposes a high intensity proton accelerator for the Neutron Science Project. A superconducting linac is a main option for the high energy part of the accelerator. Design and development work for the superconducting accelerating cavities (resonant frequency of 600 MHz) is in progress. Superconducting cavities have an advantage of very high accelerating efficiency because RF wall loss is very small and much of the RF power fed to the cavity is consumed for the beam acceleration. On the other hand, an RF input coupler for the superconducting cavity has to be matched to the beam loading. Therefore, estimation of coupling coefficient or external quality factor (Qext) of the RF input coupler is important for the design of the couplers. In this work, Qext`s were calculated by the electromagnetic analysis code (MAFIA) and were compared with those by the measurements. A {beta} (ratio of the particle velocity to the light velocity) = 0.5 single-cell cavity with either axial coupler or side coupler was used in this work. In the experiments, a model cavity made by copper is applied. Both 2- and 3-dimensional calculations were performed in the axial coupler geometry and the results were compared. The agreements between calculated and measured values are good and this method for calculation of Qext is confirmed to be proper for the design of the RF input couplers. (author)

  20. History of grating images

    Science.gov (United States)

    Iwata, Fujio

    2001-06-01

    Toppan Printing Co., Ltd. originated the name of 'grating image'. It means an image that consists of diffraction grating dots that look similar to the halftone dots of conventional printing. We proposed this new display method using simple gratings in order to enhance the visual effects when illumination is made by a fluorescent lamp. We considered the use of simple gratings as elemental dots, and used a number of elemental dots to display a 2D image. This method produces an effect something like the halftone dots of printing. The grating image technology grows from its starting to become able to produce 3D images and a 3D-video system using an electron beam grating-writing system.

  1. Optimized Ultrawideband and Uniplanar Minkowski Fractal Branch Line Coupler

    Directory of Open Access Journals (Sweden)

    Mohammad Jahanbakht

    2012-01-01

    Full Text Available The non-Euclidean Minkowski fractal geometry is used in design, optimization, and fabrication of an ultrawideband (UWB branch line coupler. Self-similarities of the fractal geometries make them act like an infinite length in a finite area. This property creates a smaller design with broader bandwidth. The designed 3 dB microstrip coupler has a single layer and uniplanar platform with quite easy fabrication process. This optimized 180° coupler also shows a perfect isolation and insertion loss over the UWB frequency range of 3.1–10.6 GHz.

  2. Grating image technology

    Science.gov (United States)

    Iwata, Fujio

    1995-07-01

    The word 'grating image' was first named by Toppan Printing Company, Ltd. It means that an image consists of grating dots. In 1988, we presented this new technology at the Optical Security Systems Symposium, in Switzerland. Then it was improved and applied in display application. Recently, it was further applied in 3D video systems. In this report, the development history and the recent situations of grating image technology are described.

  3. Tunable continuous-wave dual-wavelength laser by external-cavity superluminescent diode with a volume Bragg grating and a diffraction grating

    Science.gov (United States)

    Zheng, Yujin; Kurita, Takashi; Sekine, Takashi; Kato, Yoshinori; Kawashima, Toshiyuki

    2016-10-01

    We demonstrate the tunable continuous-wave dual-wavelength laser based on a double external-cavity superluminescent diode (SLD). The double external cavity consisted of a volume Bragg grating (VBG) and a diffraction grating bracketing the SLD's two facets. The VBG was used as an output coupler to enable the external-cavity SLD to achieve a stable wavelength. A narrow bandwidth of 0.25 nm was achieved in single-wavelength operation. The diffraction grating served as an end mirror to create another tunable wavelength external cavity for the SLD. A wavelength tuning range of 23 nm was achieved. The laser output of the double external-cavity SLD had a tunable spectral separation with dual-wavelengths from +6.42 to -16.94 nm. An output power of up to 37.7 mW was achieved with a frequency difference of 7.1 THz.

  4. Generalized Analytical Solutions for Nonlinear Positive-Negative Index Couplers

    Directory of Open Access Journals (Sweden)

    Zh. Kudyshev

    2012-01-01

    Full Text Available We find and analyze a generalized analytical solution for nonlinear wave propagation in waveguide couplers with opposite signs of the linear refractive index, nonzero phase mismatch between the channels, and arbitrary nonlinear coefficients.

  5. Unconsumed precursors and couplers after formation of oxidative hair dyes

    DEFF Research Database (Denmark)

    Rastogi, Suresh Chandra; Søsted, Heidi; Johansen, Jeanne Duus

    2006-01-01

    Contact allergy to hair dye ingredients, especially precursors and couplers, is a well-known entity among consumers having hair colouring done at home or at a hairdresser. The aim of the present investigation was to estimate consumer exposure to some selected precursors (p-phenylenediamine, toluene......-2,5-diamine) and couplers (3-aminophenol, 4-aminophenol, resorcinol) of oxidative hair dyes during and after hair dyeing. Concentrations of unconsumed precursors and couplers in 8 hair dye formulations for non-professional use were investigated, under the conditions reflecting hair dyeing. Oxidative...... hair dye formation in the absence of hair was investigated using 6 products, and 2 products were used for experimental hair dyeing. In both presence and absence of hair, significant amounts of unconsumed precursors and couplers remained in the hair dye formulations after final colour development. Thus...

  6. New design of 2-D photonic crystal waveguide couplers

    Institute of Scientific and Technical Information of China (English)

    ZHONG Zhi-rong; ZHANG Li-hua; YANG Hong-qin; JIANG Yun-kun

    2006-01-01

    @@ Based on couple wave equation and finite-difference time-domain (FDTD) algorithm,the strong couple characteristic of 2-D photonic crystal couplers is calculated.Theoretical analysis and numerical simulated results indicate that the energy in a 2-D photonic crystal coupler can not be totally transferred between two wave-guides.Compared with the result of weak coupling theory,our result is more accurate.

  7. Bragg gratings in Topas

    DEFF Research Database (Denmark)

    Zhang, C.; Webb, D.J.; Kalli, K.

    We report for the first time fibre Bragg grating inscription in microstructured optical fibre fabricated from Topas® cyclic olefin copolymer. The temperature sensitivity of the grating was studied revealing a positive Bragg wavelength shift of approximately 0.8 nmK-1,the largest sensitivity yet...

  8. Structure analysis of optical fiber coupler with infrared spectrometry

    Institute of Scientific and Technical Information of China (English)

    段吉安; 帅词俊; 苗健宇; 钟掘

    2004-01-01

    To obtain excellent performance optical fiber couplers, the structural difference of SiO2 in couplers with different manufacturing techniques was investigated. With 740-FT-IR infrared spectrometric analyzer, the infrared absorption spectrum of SiO2 in couplers at different drawing velocities was measured, and two characteristic peaks in the wavenumber range of 650 - 2000 cm-1 were observed. One characteristic peak is at about 943 cm-1 , which is attributed to Si-O Si bond asymmetric stretching vibration, the other is at about 773 cm-1 , which is attributed to Si-O-Si bond symmetric stretching vibration. From the infrared spectrum, it is found that the intensity and wavenumber of the characteristic peaks are related to the manufacturing technique of couplers. The characteristic peak at about 943 cm-1 becomes steeper when increasing the drawing velocity. At the drawing velocity of 150 μm/s, the distance between the two characteristic peaks is maximum, and then the optical fiber coupler has excellent performance, indicating that the performance of the optical fiber coupler has a close relationship with the wavenumber of the two characteristic peaks.

  9. Power coupler kick of the TRIUMF ICM capture cavities

    Science.gov (United States)

    Yan, Fang; E. Laxdal, R.; Zvyagintsev, V.; Yu., Chao; C., Gong; Koscielniak, S.

    2011-06-01

    The TRIUMF Injector CryoModule (ICM) adapted two superconducting single cavities as the capture section for the low injecting energy of 100 keV electrons. Coupler kick induced beam deflection and projected emittance growth are one of the prime concerns of the beam stability, especially at low energies. In low energy applications, the electron velocity changes rapidly inside the cavity, which makes the numerical analysis much more complicated. The commonly used theoretical formulas of the direct integral or the Panofsky-Wenzel theorem is not suitable for the kick calculation of β < 1 electrons. Despite that, the above mentioned kick calculation method doesn't consider injecting electron energy, the beam offset due to the coupler kick may not be negligible because of the low injection energy even if the kick is optimized. Thus the beam dynamics code TRACK is used here for the simulation of the power coupler kick perturbation. The coupler kick can be compensated for by a judicious choice of the coupler position in successive cavities from upstream to downstream. The simulation shows that because of the adiabatic damping by the following superconducting 9-cell cavity, even for the worst orbit distortion case after two capture cavities, the kick is still acceptable at the exit of the ICM after reaching 10 MeV. This paper presents the analysis of the transverse kick and the projected emittance growth induced by the coupler for β < 1 electrons. The simulated results of the TRIUMF ICM capture cavities are described and presented.

  10. Power coupler kick of the TRIUMF ICM capture cavities

    Institute of Scientific and Technical Information of China (English)

    YAN Fang; R.E. Laxdal; V. Zvyagintsev; Yu. Chao; C. Gong; S. Koscielniak

    2011-01-01

    The TRIUMF Injector CryoModule (ICM) adapted two superconducting single cavities as the capture section for the low injecting energy of 100 keV electrons. Coupler kick induced beam deflection and projected emittance growth are one of the prime concerns of the beam stability, especially at low energies. In low energy applications, the electron velocity changes rapidly inside the cavity, which makes the numerical analysis much more complicated. The commonly used theoretical formulas of the direct integral or the Panofsky- Wenzel theorem is not suitable for the kick calculation of β <1 electrons. Despite that, the above mentioned kick calculation method doesn't consider injecting electron energy, the beam offset due to the coupler kick may not be negligible because of the low injection energy even if the kick is optimized. Thus the beam dynamics code TRACK is used here for the simulation of the power coupler kick perturbation. The coupler kick can be compensated for by a judicious choice of the coupler position in successive cavities from upstream to downstream. The simulation shows that because of the adiabatic damping by the following superconducting 9-cell cavity, even for the worst orbit distortion case after two capture cavities, the kick is still acceptable at the exit of the ICM after reaching 10 MeV. This paper presents the analysis of the transverse kick and the projected emittance growth induced by the coupler for β <1 electrons. The simulated results of the TRIUMF ICM capture cavities are described and presented.

  11. Spherical grating spectrometers

    Science.gov (United States)

    O'Donoghue, Darragh; Clemens, J. Christopher

    2014-07-01

    We describe designs for spectrometers employing convex dispersers. The Offner spectrometer was the first such instrument; it has almost exclusively been employed on satellite platforms, and has had little impact on ground-based instruments. We have learned how to fabricate curved Volume Phase Holographic (VPH) gratings and, in contrast to the planar gratings of traditional spectrometers, describe how such devices can be used in optical/infrared spectrometers designed specifically for curved diffraction gratings. Volume Phase Holographic gratings are highly efficient compared to conventional surface relief gratings; they have become the disperser of choice in optical / NIR spectrometers. The advantage of spectrometers with curved VPH dispersers is the very small number of optical elements used (the simplest comprising a grating and a spherical mirror), as well as illumination of mirrors off axis, resulting in greater efficiency and reduction in size. We describe a "Half Offner" spectrometer, an even simpler version of the Offner spectrometer. We present an entirely novel design, the Spherical Transmission Grating Spectrometer (STGS), and discuss exemplary applications, including a design for a double-beam spectrometer without any requirement for a dichroic. This paradigm change in spectrometer design offers an alternative to all-refractive astronomical spectrometer designs, using expensive, fragile lens elements fabricated from CaF2 or even more exotic materials. The unobscured mirror layout avoids a major drawback of the previous generation of catadioptric spectrometer designs. We describe laboratory measurements of the efficiency and image quality of a curved VPH grating in a STGS design, demonstrating, simultaneously, efficiency comparable to planar VPH gratings along with good image quality. The stage is now set for construction of a prototype instrument with impressive performance.

  12. Application of a grating coupler for surface plasmon polariton excitation in a photoemission electron microscopy experiment

    DEFF Research Database (Denmark)

    Leißner, Till; Jauernik, Stephan; Lemke, Christoph

    Surface plasmon polariton (SPP) excitation at a gold-vacuum interface via 800 nm light pulses mediated by a periodic array of gold ridges is probed at high lateral resolution by means of photoemission electron microscopy (PEEM). We directly monitor and quantify the coupling properties as a function...

  13. Optical refractive index biosensor using evanescently coupled lateral Bragg gratings on silicon-on-insulator

    Science.gov (United States)

    Mendez-Astudillo, Manuel; Takahisa, Hiroki; Okayama, Hideaki; Nakajima, Hirochika

    2016-08-01

    In this paper, we present a compact silicon-on-insulator optical biosensor based on lateral Bragg gratings evanescently coupled to a waveguide. The device is fabricated by electron-beam lithography and dry-etched in a single step with inductive coupled plasma reactive ion etching (ICP-RIE). Fully etched grating couplers are used to couple the light in and out of the chip, while lateral Bragg gratings are used as the sensing element of the device. A sensitivity of 22 nm/RIU is obtained by exposing the device to deionized water with different NaCl concentrations with a footprint area of 15 × 4 µm2 that allows for densely multiplexed solutions.

  14. Prepolymer-based waveguiding thin films for the holographic recording of dry-developing refractive-index gratings

    Science.gov (United States)

    Driemeier, W.

    1990-04-01

    A new concept is presented for the easy preparation of polymer systems which are characterized by a persistent photoinduced refractive-index change. These organic materials are based upon highly viscous prepolymers, reactive multifunctional thinners and uv-photoinitiators used in very high concentrations of max. 25%. Waveguiding thin films are applied for the optical recording of refractive-index gratings. The index modulation is enhanced by a dry development at 20-50°C up to 1.0×10 -2. A holographically produced grating coupler reaches efficiencies of 33% for an incident HeNe laser beam.

  15. Preliminary Investigation of an SOI-based Arrayed Waveguide Grating Demodulation Integration Microsystem

    Science.gov (United States)

    Li, Hongqiang; Zhou, Wenqian; Liu, Yu; Dong, Xiaye; Zhang, Cheng; Miao, Changyun; Zhang, Meiling; Li, Enbang; Tang, Chunxiao

    2014-01-01

    An arrayed waveguide grating (AWG) demodulation integration microsystem is investigated in this study. The system consists of a C-band on-chip LED, a 2 × 2 silicon nanowire-based coupler, a fiber Bragg grating (FBG) array, a 1 × 8 AWG, and a photoelectric detector array. The coupler and AWG are made from silicon-on-insulator wafers using electron beam exposure and response-coupled plasma technology. Experimental results show that the excess loss in the MMI coupler with a footprint of 6 × 100 μm2 is 0.5423 dB. The 1 × 8 AWG with a footprint of 267 × 381 μm2 and a waveguide width of 0.4 μm exhibits a central channel loss of −3.18 dB, insertion loss non-uniformity of −1.34 dB, and crosstalk level of −23.1 dB. The entire system is preliminarily tested. Wavelength measurement precision is observed to reach 0.001 nm. The wavelength sensitivity of each FBG is between 0.04 and 0.06 nm/dB. PMID:24797561

  16. Influence of load by high power on the optical coupler

    Science.gov (United States)

    Bednarek, Lukas; Poboril, Radek; Vanderka, Ales; Hajek, Lukas; Nedoma, Jan; Vasinek, Vladimir

    2016-12-01

    Nowadays, aging of the optical components is a very current topic. Therefore, some investigations are focused on this area, so that the aging of the optical components is accelerated by thermal, high power and gamma load. This paper deals by findings of the influence of the load by laser with high optical power on the transmission parameters of the optical coupler. The investigated coupler has one input and eight outputs (1x8). Load by laser with high optical power is realized using a fiber laser with a cascade configuration EDFA amplifiers. The output power of the amplifier is approximately 250 mW. Duration of the load is moving from 104 hours to 139 hours. After each load, input power and output powers of all branches are measured. Following parameters of the optical coupler are calculated using formulas: the insertion losses of the individual branches, split ratio, total losses, homogeneity of the losses and cross-talk between different branches. All measurements are performed at wavelengths 1310 nm and 1550 nm. Individual optical powers are measured 20 times, due to the exclusion of statistical error of the measurement. After measuring, the coupler is connected to the amplifier for next cycle of the load. The paper contains an evaluation of the results of the coupler before and after four cycles of the burden.

  17. Gratings in polymeric waveguides

    Science.gov (United States)

    Mishakov, G.; Sokolov, V.; Kocabas, A.; Aydinli, A.

    2007-04-01

    Laser-induced formation of polymer Bragg grating filters for Dense Wavelength Division Multiplexing (DWDM) applications is discussed. Acrylate monomers halogenated with both fluorine and chlorine, which possess absorption losses less than 0.25 dB/cm and wide choice of refractive indices (from 1.3 to 1.5) in the 1.5 μm telecom wavelength region were used. The monomers are highly intermixable thus permitting to adjust the refractive index of the composition within +/-0.0001. Moreover they are photocurable under UV exposure and exhibit high contrast in polymerization. These properties make halogenated acrylates very promising for fabricating polymeric waveguides and photonic circuits. Single-mode polymer waveguides were fabricated on silicon wafers using resistless contact lithography. Submicron index gratings have been written in polymer waveguides using holographic exposure with He-Cd laser beam (325 nm) through a phase mask. Both uniform and apodized gratings have been fabricated. The gratings are stable and are not erased by uniform UV exposure. The waveguide gratings possess narrowband reflection spectra in the 1.5 μm wavelength region of 0.4 nm width, nearly rectangular shape of the stopband and reflectivity R > 99%. The fabricated Bragg grating filters can be used for multiplexing/demultiplexing optical signals in high-speed DWDM optical fiber networks.

  18. Multipitched Diffraction Gratings for Surface Plasmon Resonance-Enhanced Infrared Reflection Absorption Spectroscopy.

    Science.gov (United States)

    Petefish, Joseph W; Hillier, Andrew C

    2015-11-03

    We demonstrate the application of metal-coated diffraction gratings possessing multiple simultaneous pitch values for surface enhanced infrared absorption (SEIRA) spectroscopy. SEIRA increases the magnitude of vibrational signals in infrared measurements by one of several mechanisms, most frequently involving the enhanced electric field associated with surface plasmon resonance (SPR). While the majority of SEIRA applications to date have employed nanoparticle-based plasmonic systems, recent advances have shown how various metals and structures lead to similar signal enhancement. Recently, diffraction grating couplers have been demonstrated as a highly tunable platform for SEIRA. Indeed, gratings are an experimentally advantageous platform due to the inherently tunable nature of surface plasmon excitation at these surfaces since both the grating pitch and incident angle can be used to modify the spectral location of the plasmon resonance. In this work, we use laser interference lithography (LIL) to fabricate gratings possessing multiple pitch values by subjecting photoresist-coated glass slides to repetitive exposures at varying orientations. After metal coating, these gratings produced multiple, simultaneous plasmon peaks associated with the multipitched surface, as identified by infrared reflectance measurements. These plasmon peaks could then be coupled to vibrational modes in thin films to provide localized enhancement of infrared signals. We demonstrate the flexibility and tunability of this platform for signal enhancement. It is anticipated that, with further refinement, this approach might be used as a general platform for broadband enhancement of infrared spectroscopy.

  19. Ultrawide Bandwidth 180°-Hybrid-Coupler in Planar Technology

    Directory of Open Access Journals (Sweden)

    Steffen Scherr

    2014-01-01

    Full Text Available A new concept of an ultrawide bandwidth 180°-hybrid-coupler is presented. The ultrawideband design approach is based on the excitation of a coplanar waveguide (CPW mode and a coupled slot line (CSL mode in the same double slotted planar waveguide. The coupler is suitable for realization in planar printed circuit board technology. For verification of the new concept a prototype was designed for the frequency range from 3 GHz to 11 GHz, built, and measured. The measurement results presented in this paper show a good agreement between simulation and measurement and demonstrate the very broadband performance of the new device. The demonstrated coupler with a size of 40 mm × 55 mm exhibits a fractional bandwidth of 114% centered at 7 GHz with a maximum amplitude imbalance of 0.8 dB and a maximum phase imbalance of 5°.

  20. Thin-ribbon tapered coupler for dielectric waveguides

    Science.gov (United States)

    Yeh, C.; Otoshi, T. Y.; Shimabukuro, F. I.

    1994-05-01

    A recent discovery shows that a high-dielectric constant, low-loss, solid material can be made into a ribbon-like waveguide structure to yield an attenuation constant of less than 0.02 dB/m for single-mode guidance of millimeter/submillimeter waves. One of the crucial components that must be invented in order to guarantee the low-loss utilization of this dielectric-waveguide guiding system is the excitation coupler. The traditional tapered-to-a-point coupler for a dielectric rod waveguide fails when the dielectric constant of the dielectric waveguide is large. This article presents a new way to design a low-loss coupler for a high- or low-dielectric constant dielectric waveguide for millimeter or submillimeter waves.

  1. Modeling seawater salinity and temperature sensing based on directional coupler assembled by polyimide-coated micro/nanofibers.

    Science.gov (United States)

    Wang, Shanshan; Liao, Yipeng; Yang, Hongjuan; Wang, Xin; Wang, Jing

    2015-12-01

    The salinity and temperature of seawater are important parameters in oceanography. Based on the directional coupler assembled by polyimide-coated micro/nanofibers, optical sensors with high sensitivity for simultaneous salinity and temperature sensing in seawater are proposed. Dependences of sensitivities on wavelength, salinity, and temperature are investigated theoretically, with which performances of such sensor under general sea conditions can be evaluated. Results show that salinity and temperature sensitivities can reach levels of nm/‰ and nm/°C, which are much higher than those of fiber Bragg gratings, knot resonators, and photonic crystal fibers. Other considerations for system design such as the length of the coupling area, the diameter difference between two fibers, and the thickness of polyimide coatings are also discussed. Sensors proposed here suggest a simple approach to realize high-sensitivity micro/nanofiber optical sensing of salinity and temperature in seawater simultaneously and may find applications in developing miniature sensors used in seawater.

  2. Simultaneous measurement of both magnetic field strength and temperature with a microfiber coupler based fiber laser sensor

    Science.gov (United States)

    Wei, Fangfang; Mallik, Arun Kumar; Liu, Dejun; Han, Wei; Lian, Xiaokang; Farrell, Gerald; Wu, Qiang; Peng, Gang-Ding; Semenova, Yuliya

    2017-04-01

    In this paper we propose and investigate a novel magnetic field sensor based of a ring erbium-doped fiber laser combined with a fiber Bragg grating and a Sagnac loop containing a microfiber coupler and magnetic fluid. In addition to the magnetic field sensing capability, the proposed structure can simultaneously provide temperature information. Thanks to the dual-ring structure of the MFC-Sagnac loop and the FBG-assisted resonant cavity, the output has two distinct laser peaks. Experimentally demonstrated magnetic field sensitivity of one of the laser peaks is 15 pm/mT in the magnetic field range from 0 to 100 mT. The spectral position of the second laser peak is independent on the magnetic field but shifts towards long wavelengths with a sensitivity of 13 pm/°C.

  3. Transmission and Distribution of Optical Field in Prism Coupler

    Energy Technology Data Exchange (ETDEWEB)

    Huang, C Q; Chen, M [College of Physics and Electronics Information, Hunan Institute of Science and Technology, Yueyang 414006 (China); Liu, J; Wan, Z M; Luo, Z M [College of Information and Communication Engineering, Hunan Institute of Science and Technology, Yueyang 414006 (China); Tian, P, E-mail: namecqh@yahoo.com.cn [College of Optoelectronic Science and Engineering, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, 430074 (China)

    2011-02-01

    Transmission and distribution characteristics of optical field in prism coupler are studies, and the phase matching function of prism coupler is deduced based on coupled wave theory. It is shown that the stable light field distribution and mode pattern are determined by its own geometric and dielectric parameters, but have nothing to do with the categories of incident light sources. It is also found that the coupling effect would generate between waveguides through evanescent field. Our numerical simulation is based on the finite difference time domain method with perfectly matched layer absorbing boundary condition. The simulation program is compiled in MATLAB. The simulation results are analyzed carefully.

  4. Artificial Neural Network Model for Optical Fiber Direction Coupler Design

    Institute of Scientific and Technical Information of China (English)

    李九生; 鲍振武

    2004-01-01

    A new approach to the design of the optical fiber direction coupler by using neural network is proposed. To train the artificial neural network,the coupling length is defined as the input sample, and the coupling ratio is defined as the output sample. Compared with the numerical value calculation of the theoretical formula, the error of the neural network model output is 1% less.Then, through the model, to design a broadband or a single wavelength optical fiber direction coupler becomes easy. The method is proved to be reliable, accurate and time-saving. So it is promising in the field of both investigation and application.

  5. Hollow-core tapered coupler for large inner diameter hollow-core optical fibers

    Institute of Scientific and Technical Information of China (English)

    Guiyao Zhou(周桂耀); Zhiyun Hou(侯峙云); Lantian Hou(侯蓝田); Jigang Liu(刘继刚)

    2003-01-01

    A novel hollow-core tapered coupler has been theoretically designed and fabricated by fiber drawing machine. The coupler's inner wall is coated with a polycrystalline GeO2 film. The coupling loss of hollow-core tapered coupler is about 0.2 dB. Hollow-core tapered coupler reduces the transmission loss of hollow-core optical fiber (HCOF) by 0.5 dB/m, therefore the coupler is suitable for coupling high power CO2 laser in industrial application.

  6. Impedance matching vertical optical waveguide couplers for dense high index contrast circuits.

    Science.gov (United States)

    Sun, Rong; Beals, Mark; Pomerene, Andrew; Cheng, Jing; Hong, Ching-Yin; Kimerling, Lionel; Michel, Jurgen

    2008-08-04

    We designed and demonstrated a compact, high-index contrast (HIC) vertical waveguide coupler for TE single mode operation with the lowest coupling loss of 0.20 dB +/- 0.05 dB at 1550 nm. Our vertical coupler consists of a pair of vertically overlapping inverse taper structures made of SOI and amorphous silicon. The vertical coupler can suppress power oscillation observed in regular directional couplers and guarantees vertical optical impedance matching with great tolerance for fabrication and refractive index variations of the waveguide materials. The coupler furthermore shows excellent broadband coupling efficiencies between 1460 nm and 1570 nm.

  7. A HIGH POWER RF COUPLER DESIGN FOR MUON COOLING RF CAVITIES.

    Energy Technology Data Exchange (ETDEWEB)

    CORLETT,J.; LI,DERUN; RIMMER,R.; HOLTKAMP,N.; MORETTI,A.; KIRK,H.G.

    1999-03-29

    We present a high power RF coupler design for an interleaved {pi}/2 805 MHz standing wave accelerating structure proposed for an muon cooling experiment at FNAL. The coupler, in its simplest form, is a rectangular waveguide directly connected to an accelerating Cell through an open slot on the cavity side-wall or end-plates. Two of such couplers are needed to feed the interleaved cavities. Current high power RF test requires the coupler to be at critical coupling. Numerical simulations on the coupler designs using MAFIA will be presented.

  8. Effect of technological parameters on optical performance of fiber coupler

    Institute of Scientific and Technical Information of China (English)

    SHUAI Ci-jun; DUAN Ji-an; ZHONG Jue

    2007-01-01

    To find out the influence of technological parameters on optical performance of fused optical fiber device, the fiber coupler was served as subject investigated by using the fused biconical taper machining as experimental setup. Fused fiber coupler's optical performances such as insertion loss, excess loss, directivity and uniformity were tested with the optical test system that was constituted of tunable laser and optical spectrum analyzer. Especially the relationship between optical performance and drawing speed was investigated. The experimental results show that the optical performance is closely related to process conditions. At fused temperature of 1 200℃, there exists a drawing speed of 150 μm/s, which makes the device's performance optimum. Out of this speed region, the optical performance drops quickly. At drawing speed of 200 tm/s, the excess loss is relatively small when the fused temperature is above 1 200℃. So the technological parameters have close relationship with optical performance of the coupler, and the good performance coupler can't get until the drawing speed and fused temperature match accurately.

  9. Cancellation of RF Coupler-Induced Emittance Due to Astigmatism

    Energy Technology Data Exchange (ETDEWEB)

    Dowell, David H.; /SLAC

    2016-12-11

    It is well-known that the electron beam quality required for applications such as FEL’s and ultra-fast electron diffraction can be degraded by the asymmetric fields introduced by the RF couplers of superconducting linacs. This effect is especially troublesome in the injector where the low energy beam from the gun is captured into the first high gradient accelerator section. Unfortunately modifying the established cavity design is expensive and time consuming, especially considering that only one or two sections are needed for an injector. Instead, it is important to analyze the coupler fields to understand their characteristics and help find less costly solutions for their cancellation and mitigation. This paper finds the RF coupler-induced emittance for short bunches is mostly due to the transverse spatial sloping or tilt of the field, rather than the field’s time-dependence. It is shown that the distorting effects of the coupler can be canceled with a static (DC) quadrupole lens rotated about the z-axis.

  10. Synthesis and analysis of coupler curves with combined planar cam ...

    African Journals Online (AJOL)

    user

    works are done on the synthesis of coupler curves or path generation using four bar mechanism. The present work ..... Sadler, J.P., and Yang, Z. 1990. Optimal design of cam-linkage mechanisms for dynamic-force characteristics. Journal of.

  11. 1×2 demultiplexer for a light waveguide communications system based on a holographic grating

    Science.gov (United States)

    Ren, Xuechang; Zhang, Xiangsu; Wang, Canhui; Liu, Shou

    2009-05-01

    2-channel multiplexer/demultiplexer (Muxer/Demuxer) is a key component for bidirectional data traffics applied for optical communication. Up to date various types of Muxer/Demuxer have been proposed and demonstrated. A grating coupler diffracts light into substrates or waveguides, along which light beam propagates by total internal reflection. In addition, one can exploit the dispersive and filtering characteristics of gratings, for dropping or separating one or several wavelengths from one another. When a laser beam containing two wavelengths is striking the surface of the grating with an incident angle within certain range, four diffracted beams will be generated. If two diffracted beams, corresponding to different wavelengths, meet the condition of total internal reflection, they will propagate inside the glass substrate (performs as a waveguide). While the third one cannot meet total reflection condition, and the last one should become the evanescent wave. Therefore it can separate two signals and couple signals to different waveguides. These functions are suited for WDM application and directional couplers. For convenience sake, the visible lights at 458nm and 633nm were used as the incident laser beams. To give a simple sample for 1×2 demultiplexing system, a holographic grating was recorded, with the period around 441nm which was chose discretionally within the certain range. The primary experimental results indicate that the two-wavelength signal can be separated and coupled into the respective waveguide as long as the grating is recorded and operated complying with the certain condition. The average insertion loss and crosstalk of the device were presented in this paper.

  12. Ultra-High Temperature Gratings

    Institute of Scientific and Technical Information of China (English)

    John Canning; Somnath Bandyopadhyay; Michael Stevenson; Kevin Cook

    2008-01-01

    Regenerated gratings seeded by type-Ⅰ gratings are shown to withstand temperatures beyond 1000 ℃. The method of regeneration offers a new approach to increasing temperature resistance of stable fibre Bragg and other gratings. These ultra-high temperature (UHT) gratings extend the applicability of silicate based components to high temperature applications such as monitoring of smelters and vehicle and aircraft engines to high power fibre lasers.

  13. Integral Method for Gratings

    CERN Document Server

    Maystre, Daniel

    2014-01-01

    The chapter contains a detailed presentation of the surface integral theory for modelling light diffraction by surface-relief diffraction gratings having a one-dimensional periodicity. Several different approaches are presented, leading either to a single integral equation, or to a system of coupled integral equations. Special attention is paid to the singularities of the kernels, and to different techniques to accelerate the convergence of the numerical computations. The theory is applied to gratings having different profiles with or without edges, to real metal and dielectrics, and to perfectly conducting substrates.

  14. Circular Fibonacci gratings.

    Science.gov (United States)

    Gao, Nan; Zhang, Yuchao; Xie, Changqing

    2011-11-01

    We introduce circular Fibonacci gratings (CFGs) that combine the concept of circular gratings and Fibonacci structures. Theoretical analysis shows that the diffraction pattern of CFGs is composed of fractal distributions of impulse rings. Numerical simulations are performed with two-dimensional fast Fourier transform to reveal the fractal behavior of the diffraction rings. Experimental results are also presented and agree well with the numerical results. The fractal nature of the diffraction field should be of great theoretical interest, and shows potential to be further developed into practical applications, such as in laser measurement with wideband illumination.

  15. A coaxial HOM coupler for a superconducting RF cavity and its low-power measurement results

    Institute of Scientific and Technical Information of China (English)

    SUN An; TANG Ya-Zhe; ZHANG Li-Ping; LI Ying-Min; Han-Sung Kim

    2011-01-01

    A resonant buildup of beam-induced fields in a superconducting radio frequency(RF)cavity may make a beam unstable or a superconducting RF cavity quench. Higher-order mode(HOM)couplers are used for damping higher-order modes to avoid such a resonant buildup. A coaxial HOM coupler based on the TTF (TESLA Test Facility)HOM coupler has been designed for the superconducting RF cavities at the Proton Engineering Frontier Project(PEFP)in order to overcome notch frequency shift and feed-through tip melting issues. In order to confirm the HOM coupler design and finalize its structural dimensions, two prototype HOM couplers have been fabricated and tested. Low-power testing and measurement of the HOM couplers has shown that the HOM coupler has good filter properties and can fully meet the damping requirements of the PEFP low-beta superconducting RF linac.

  16. Grating-coupled silicon-on-sapphire integrated slot waveguides operating at mid-infrared wavelengths.

    Science.gov (United States)

    Zou, Yi; Subbaraman, Harish; Chakravarty, Swapnajit; Xu, Xiaochuan; Hosseini, Amir; Lai, Wei-Cheng; Wray, Parker; Chen, Ray T

    2014-05-15

    We demonstrate subwavelength bidirectional grating (SWG) coupled slot waveguide fabricated in silicon-on-sapphire for transverse electric polarized wave operation at 3.4 μm wavelength. Coupling efficiency of 29% for SWG coupler is experimentally achieved. Propagation loss of 11  dB/cm has been experimentally obtained for slot waveguides. Two-step taper mode converters with an insertion loss of 0.13 dB are used to gradually convert the strip waveguide mode into slot waveguide mode.

  17. Compact wavelength add-drop multiplexers using Bragg gratings in coupled dielectric-loaded plasmonic waveguides

    CERN Document Server

    Biagi, Giulio; Radko, Ilya P; Rubahn, Horst-Günter; Pedersen, Kjeld; Bozhevolnyi, Sergey I

    2016-01-01

    We report a novel design of a compact wavelength add-drop multiplexer utilizing dielectric-loaded surface plasmon-polariton waveguides (DLSPPWs). The DLSPPW-based configuration exploits routing properties of directional couplers and filtering abilities of Bragg gratings. We present practical realization of a 20-$\\mu$m-long device operating at telecom wavelengths that can reroute optical signals separated by approximately 70 nm in the wavelength band. We characterize the performance of the fabricated structures using scanning near-field optical microscopy as well as leakage-radiation microscopy and support our findings with numerical simulations.

  18. Distributed acoustic sensing system using an identical weak fiber Bragg grating array

    Science.gov (United States)

    Liu, Sheng; Han, Xinying; Wen, Hongqiao

    2016-10-01

    We propose and experimentally demonstrate a distributed acoustic sensing system using an identical weak fiber Bragg grating array. Phase, frequency and location information of vibration can be demodulated by using a path-match interferometry method. 3×3 coupler demodulation technique is employed to eliminate signal fading in interferometer. Experiments on detecting acoustic wave generated by PZT show that the system is capable of measuring vibrations of up to 1000 Hz over 1.6 km with 2.5m spatial resolution.

  19. Broad-area and MOPA lasers with integrated grating components for beam shaping and novel functions

    Science.gov (United States)

    Suhara, Toshiaki; Uemukai, Masahiro; Shimada, Naoyuki; Larsson, Anders

    2003-07-01

    The work of the authors' group on monolithic integrated in-plane semiconductor lasers using grating components are reviewed and the recent development is reported. The grating components provide not only feedback for lasing but also novel functions such as output beam shaping and wavelength tuning. The design and fabrication of the grating components in semiconductor waveguide are outlined, and the area-selective quantum-well disordering by impurity-free vacancy diffusion is described as an effective technique to reduce the absorption loss in the passive waveguide. Then, device description, design, fabrication and experimental results of integrated master oscillator power amplifier (MOPA) lasers, high-power tunable extended-cavity lasers, and a broad-area angled-grating distributed Bragg reflector (DBR) lasers using InGaAs/AlGaAs GRIN-SCH-SQW structures are presented. All the lasers have integrated beam forming grating coupler, and allow implementation of compact and stable lensless modules that emit a collimated output beam.

  20. Sensored fiber reinforced polymer grate

    Energy Technology Data Exchange (ETDEWEB)

    Ross, Michael P.; Mack, Thomas Kimball

    2017-08-01

    Various technologies described herein pertain to a sensored grate that can be utilized for various security fencing applications. The sensored grate includes a grate framework and an embedded optical fiber. The grate framework is formed of a molded polymer such as, for instance, molded fiber reinforced polymer. Further, the grate framework includes a set of elongated elements, where the elongated elements are spaced to define apertures through the grate framework. The optical fiber is embedded in the elongated elements of the grate framework. Moreover, bending or breaking of one or more of the elongated elements can be detected based on a change in a characteristic of input light provided to the optical fiber compared to output light received from the optical fiber.

  1. Study of a single longitudinal fiber ring laser with a π phase-shifted fiber Bragg grating

    Science.gov (United States)

    Wang, Weitao; Song, Zhiqiang; Qi, Haifeng; Zhang, Xiaolei; Ni, Jiasheng; Guo, Jian; Wang, Chang; Peng, Gangding

    2017-08-01

    A single-longitudinal-mode fiber laser is presented, which is composed of a ring cavity laser and a π phase-shifted fiber Bragg grating. The ring cavity structure can reduce the spatial hole burning, but the mode hopping and competition are still existing due to the long fiber ring cavity length. The π phase-shifted fiber Bragg grating has very narrow transmittance spectrum width as a band-pass filter. Combined with a wavelength-matching fiber Bragg grating, it is able to efficiently suppress the mode hopping and competition in the ring cavity. The single longitudinal mode lasing is verified using a scanning F-P interferometer. Its frequency noise is measured by the self-homodyne technology with a 3×3 optical fiber coupler. The calculated linewidth from the frequency noise is about 21 kHz when the measurement time is 0.2 s.

  2. Study of WDM polymer planar curved waveguide couplers

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A wavelength division multiplexer based on curved polymer planar waveguide is proposed. According to the coupled mode theory and the waveguide structure, the performance of the curved waveguide coupler (CWC) is analyzed. The results show that CWC can accommodate wider multiplexing bandwidth than parallel straight waveguide coupler (SWC) due to the compensation effect of the effective coupling length. The two variables, curvature radius and minimum spacing, increase the design flexibility of the waveguide device. A 4-channel wavelength division multiplexing (WDM) system based on CWC is designed. The deviation of the center wavelength, due to the errors of curvature radius and minimum spacing during fabrication process, is investigated. The smaller the curvature radius and the minimum spacing are, the larger the central wavelength deviation caused by the error of the curvature radius and the minimum spacing is, which provides some useful theoretical basis for the design and the fabrication of polymer waveguide devices.

  3. Optical mode switch based on multimode interference couplers

    Science.gov (United States)

    Xiao, Huifu; Deng, Lin; Zhao, Guolin; Liu, Zilong; Meng, Yinghao; Guo, Xiaonan; Liu, Guipeng; Liu, Su; Ding, Jianfeng; Tian, Yonghui

    2017-02-01

    In this paper, we propose an optical mode switch based on two cascaded multimode interference (MMI) couplers. After a fundamental mode divided into two equal-power fundamental modes in the first MMI coupler, the thermo-optic effect is employed to modulate the phase of the two fundamental modes before directed to the next MMI for the purpose of mode switching. By adjusting the electric signals applied to the modulation arms, the proposed device can implement mode switching in three states: (a) one first-order and two fundamental modes simultaneously output, (b) one first-order mode output, and (c) two fundamental modes output. As a result, the simulated excess losses are -0.29 dB, -0.10 dB, and -0.63 dB, respectively.

  4. Power Coupler Simulations for the Linac4 Drift Tube Linac

    CERN Document Server

    De Michele, G; Ramberger, S

    2011-01-01

    The power coupler is a crucial element in the design of an RF cavity. Power from an RF source is transported towards the cavity by a waveguide and transferred into the cavity by means of a power coupler that is adapted to both the transport mode in the waveguide and the principal resonant mode in the cavity. In the case of Linac4, a rectangular half-height waveguide (WG) WR2300 is used and the connection from this WG to the cavity is achieved by iris coupling through an interconnecting waveguide (IWG) in the tank wall. In this note simulations and measurements on a prototype and studies on Tank1 of the Linac4 Drift Tube Linac (DTL) are discussed in order to define the dimensions of this IWG such that it optimises the power transfer into the cavity.

  5. Nonideal effects in quantum field-effect directional coupler

    Institute of Scientific and Technical Information of China (English)

    Xie Yue-E; Yan Xiao-Hong; Chen Yuan-Ping

    2006-01-01

    The nonideal effects in a quantum field-effect directional coupler where two quantum wires are coupled through a finite potential barrier are studied by adopting the lattice Green function method. The results show that the electron energy distribution, asymmetric geometry and finite temperature all have obvious influence on the electron transfer of the coupler. Only for the electrons with energies in a certain region, can the complete periodic transfer between two quantum wires take place. The conductance of these electrons as a function of the barrier length and potential height exhibits a fine periodic or quasi-periodic pattern. For the electrons with energies beyond the region, however, the complete periodic transfer does not hold any more since many irregular oscillations are superimposed on the conductance profile. In addition, the finite temperature and asymmetric geometry both can reduce the electron transfer efficiency.

  6. Compact dipole nanoantenna coupler to plasmonic slot waveguide

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Malureanu, Radu; Biagi, Giulio;

    2012-01-01

    Optical nanoantennas can be used for coupling radiation to or from waveguides in analogy to micro- and radio-wave systems. In this letter we provide a systematic description of the design approaches for a coupler to a plasmonic slot waveguide in the telecom range around 1.55 µm with realistic...... excitation from a lensed optical fiber. We show that the best coupling efficiency of 26% can be achieved by utilizing a dipole antenna with side and bottom reflectors, and such coupling efficiency is 185 times larger than for the bare waveguide. The nanoantenna coupler provides a compact interface between...... an optical fiber and a plasmonic slot waveguide for future optical integrated circuits....

  7. Resonant terahertz absorption by plasmons in grating-gate GaN HEMT structures

    Science.gov (United States)

    Muravjov, A. V.; Veksler, D. B.; Hu, X.; Gaska, R.; Pala, N.; Saxena, H.; Peale, R. E.; Shur, M. S.

    2009-05-01

    Pronounced resonant absorption and frequency dispersion associated with an excitation of collective 2D plasmons have been observed in terahertz (0.5-4THz) transmission spectra of grating-gate 2D electron gas AlGaN/GaN HEMT (high electron mobility transistor) structures at cryogenic temperatures. The resonance frequencies correspond to plasmons with wavevectors equal to the reciprocal-lattice vectors of the metal grating, which serves both as a gate electrode for the HEMT and a coupler between plasmons and incident terahertz radiation. The resonances are tunable by changing the applied gate voltage, which controls 2D electron gas concentration in the channel. The effect can be used for resonant detection of terahertz radiation and for "on-chip" terahertz spectroscopy.

  8. HOM Coupler Notch Filter Tuning for the European XFEL Cavities

    OpenAIRE

    Sulimov, Alexey

    2015-01-01

    The notch filter (NF) tuning prevents the extraction of fundamental mode (1.3 GHz) RF power through Higher Order Modes (HOM) couplers. The procedure of NF tuning was optimized at the beginning of serial European XFEL cavities production. It allows keeping the filter more stable against temperature and pressure changes during cavity cool down. Some statistics of NF condition during cavities and modules cold tests is presented.

  9. Hybrid silicon plasmonic organic directional coupler-based modulator

    Science.gov (United States)

    Abdelatty, M. Y.; Zaki, A. O.; Swillam, M. A.

    2017-01-01

    An optical directional coupler (ODC)-based hybrid plasmonic waveguide is designed and demonstrated with a power splitting mechanism that can be tuned by applying an external electric field. The tuning mechanism takes the advantage of electro-optic properties of the embedded polymer layer. The ODC operates under 1550 nm telecommunication wavelength. A finite element method with a perfect matching layer, absorbing boundary condition, is taken up to simulate and analyze the ODC.

  10. The Asymmetric Active Coupler: Stable Nonlinear Supermodes and Directed Transport

    CERN Document Server

    Kominis, Yannis; Flach, Sergej

    2016-01-01

    We consider the asymmetric active coupler (AAC) consisting of two coupled dissimilar waveguides with gain and loss. We show that under generic conditions, not restricted by parity-time symmetry, there exist finite-power, constant-intensity nonlinear supermodes (NS), resulting from the balance between gain, loss, nonlinearity, coupling and dissimilarity. The system is shown to possess nonreciprocal dynamics enabling directed power transport and optical isolation functionality.

  11. High Strain-Rate Testing of Mechanical Couplers

    Science.gov (United States)

    2009-09-01

    tensile strength equal to or greater than that of the control bar but did not achieve the ductility of the control bar. Specimen UHC 9 failed close to...than the Grade 60 bar, but only slightly so at the rapid rate. Upset head system The upset head coupler ( UHC ) system performed very well under the...average performance of the UHC system under the intermediate strain-rate loading condition produced 99% of the dynamic ultimate strength, 61% of the

  12. Efficient Coupler for a Bessel Beam Dispersive Element

    Science.gov (United States)

    Savchenkov, Anatoliy; Iltchenko, Vladimir; Matsko, Andrey; Le, Thanh; Yu, nan; Maleki, Lute

    2008-01-01

    A document discusses overcoming efficient optical coupling to high orbital momentum modes by slightly bending the taper dispersive element. This little shape distortion is not enough to scramble the modes, but it allows the use of regular, free-beam prism coupling, fiber coupling, or planar fiber on-chip coupling with, ultimately, 100 percent efficiency. The Bessel-beam waveguide is bent near the contact with the coupler, or a curved coupler is used. In this case, every Bessel-beam mode can be successfully coupled to a collimated Gaussian beam. Recently developed Bessel-beam waveguides allow long optical delay and very high dispersion. Delay values may vary from nanoseconds to microseconds, and dispersion promises to be at 100 s/nm. Optical setup consisted of a red laser, an anamorphic prism pair, two prism couplers, and a bent, single-mode fiber attached to prisms. The coupling rate increased substantially and corresponded to the value determined by the anamorphic prism pair.

  13. State of the Art Power Couplers for Superconducting RF Cavities

    Energy Technology Data Exchange (ETDEWEB)

    Isidoro Campisi

    2002-08-01

    Simulations are now routinely performed that allow the prediction of electromagnetic, multipacting, thermal, and mechanical properties of couplers. From these studies, better designs have been conceived which can minimize potential problems ahead of construction. Judicious use of materials and the implementation of clean practices and of careful conditioning have gradually increased the power levels at which couplers can safely operate. Machine operation at hundreds of kilowatts has been achieved in CW at KEK and Cornell, and in a pulsed mode at the TESLA Test Facility (TTF). Test stand operations in CW at the megawatt level (Accelerator for the Production of Tritium) and in pulse mode at a peak power of 2 MW (Spallation Neutron Source, TTF version II) have been achieved. The recent progress indicates that the understanding of the behavior of fundamental power couplers is rapidly increasing and that optimal designs are being developed which will allow in the future to attain routine attainment of the megawatt power levels necessary for high-beam-power machines under construction and under study.

  14. Comparison of sound transmission in human ears and coupler loaded by audiometric earphones

    DEFF Research Database (Denmark)

    Ciric, Dejan; Hammershøi, Dorte

    2005-01-01

    earphones, which is related to coupling of these earphones to human ears and to the coupler. This is done by measurements of the transfer functions from input voltage of the earphone terminals to the entrance of the ear canal in two situations: open, and blocked. Similar measurements were carried out......The thresholds of hearing are usually determined using audiometric earphones. They are calibrated by means of a standardized acoustical coupler. In order to have determined thresholds independent of the earphone type, the coupler should approximate the average human ear closely. Nevertheless...... in the coupler, but since the "ear canal entrance" is not well-defined for the coupler, the mentioned measurements were done at different depths in the coupler. The sound transmission and coupling were described in terms of the pressure division at the entrance of the ear canal and the transmissions in human...

  15. Inexpensive 3dB coupler for POF communication by injection-molding production

    Science.gov (United States)

    Haupt, M.; Fischer, U. H. P.

    2011-01-01

    POFs (polymer optical fibers) gradually replace traditional communication media such as copper and glass within short distance communication systems. Primarily, this is due to their cost-effectiveness and easy handling. POFs are used in various fields of optical communication, e.g. the automotive sector or in-house communication. So far, however, only a few key components for a POF communication network are available. Even basic components, such as splices and couplers, are fabricated manually. Therefore, these circumstances result in high costs and fluctuations in components' performance. Available couplers have high insertion losses due to their manufacturing method. This can only be compensated by higher power budgets. In order to produce couplers with higher performances new fabrication methods are indispensable. A cheap and effective way to produce couplers for POF communication systems is injection molding. The paper gives an overview of couplers available on market, compares their performances, and shows a way to produce couplers by means of injection molding.

  16. Density controlled nanophotonic waveguide gratings for efficient on-chip out-coupling in the near field (Conference Presentation)

    Science.gov (United States)

    Vercruysse, Dries; Mukund, Vignesh; Jansen, Roelof; Stahl, Richard; Van Dorpe, Pol; Lagae, Liesbet; Rottenberg, Xavier

    2016-05-01

    Waveguide optics takes up a prominent role in the progressing miniaturization of optical devices. Chip integrated photonic waveguides especially allow for complex routing schemes of light across a chip. In/out-coupling diffraction gratings form an essential tool in waveguide systems, as they facilitate the interaction between the waveguide system and the near or far-field.[1,2] Ideally, these gratings would couple out all light in the waveguide into a beam with a predefined polarization and, phase and intensity profile. As such they should be able to produce any functional beam that is typically prepared by free space optics. Yet, in practice there is typically a design trade-off between beam quality and out-coupling efficiency.[2] Light in the waveguide has to travel laterally through the grating to be coupled out. The light therefore decays exponentially over the grating, causing much more light to be coupled out at the start of the grating than at the end. This asymmetry results in a warped out-coupling intensity that heavily influences the light beam's intensity profile. Especially when the grating is addressing points in the near field, as is the case for focusing waveguide grating couplers, this effect can be highly disruptive. In this work we present a grating constructed from a field of sub-wavelength scatterers, rather than full grating lines. By tuning the position and the density of the scatterers, the phase and the intensity of the out-coupled light can be set precisely over large grating areas. An iterative design algorithm is developed that carefully tunes the density so as to control the light intensity in the waveguide and the amount of out-coupled light. Using FDTD simulations we show that these gratings can efficiently couple out light into a nearly diffraction limited spot with an even angular intensity. We verify this experimentally by fabricating these gratings in the SiN/SiO2 system using e-beam lithography. In addition, we also show that

  17. Circuital Model for Post Coupler Stabilization in a Drift Tube Linac

    CERN Document Server

    Grespan, F; Ramberger, S; Vretenar, M

    2010-01-01

    Linac4 Drift Tube Linac (DTL) cavities will be equipped with Post Couplers (PCs) for field stabilization. The study presented in this paper starts with the analysis of 2D and 3D simulations of post couplers in order to develop an equivalent circuit model which can explain the post coupler stabilization working principle and define a tuning strategy for DTL cavities. Simulations and equivalent circuit results have been verified by measurements on the Linac4 DTL prototypes at CERN.

  18. Ultra-low-loss inverted taper coupler for silicon-on-insulator ridge waveguide

    DEFF Research Database (Denmark)

    Pu, Minhao; Liu, Liu; Ou, Haiyan;

    2010-01-01

    An ultra-low-loss coupler for interfacing a silicon-on-insulator ridge waveguide and a single-mode fiber in both polarizations is presented. The inverted taper coupler, embedded in a polymer waveguide, is optimized for both the transverse-magnetic and transverse-electric modes through tapering...... the width of the silicon-on-insulator waveguide from 450 nm down to less than 15 nm applying a thermal oxidation process. Two inverted taper couplers are integrated with a 3-mm long silicon-on-insulator ridge waveguide in the fabricated sample. The measured coupling losses of the inverted taper coupler...

  19. Simulation of the RF Coupler for TRIUMF ISAC-II Superconducting Quarter Wave Resonators

    CERN Document Server

    Zvyagintsev, V

    2004-01-01

    The inductive RF coupler for the TRIUMF ISAC-II 106 MHz superconducting accelerating quarter wave resonators was used as a basis for the simulation model of stationary transmission processes of RF power and thermal fluxes. Electromagnetic simulation of the coupler was done with ANSOFT HFSS code. Transmission line theory was used for electromagnetic wave calculations along the drive line to the Coupler. An analogy between electric and thermal processes allows the thermal calculations to be expressed in terms of electrical circuits. The data obtained from the simulation are compared to measured values on the RF coupler.

  20. High power conditioning of the input coupler for BEPCⅡ superconducting cavity

    Institute of Scientific and Technical Information of China (English)

    PAN Wei-Min; HUANG Tong-Ming; MA Qiang; WANG Guang-Wei; SUN Yi; SHA Peng; LI Zhong-Quan; LIN Hai-Ying; XU Bo

    2008-01-01

    High power conditioning of the input coupler for BEPCⅡ supercOnducting cavity has been performed.After room temperature conditioning,the RF power of 150 kW with continuous wave at standing wave mode passed through the coupler without any problem.Meanwhile,a series of methods have also been studied to improve the performance of the coupler during the beam operation.Up to now,the input coupler can feed a RF power up to 100 kW stably with high current of 250 mA at 2.5 GeV.

  1. Vibration measurements based on demodulating the phase of a fiber 3dB-coupler Michelson interferometer

    Science.gov (United States)

    Li, Min; Xie, Fang; Ren, Junyu

    2009-11-01

    A fiber interferometric vibration measurement system which is based on demodulating the phase of a fiber Michelson interferometer which is made with a fiber 3dB-coupler is presented. In the work, the system employed the characteristics of fiber Brag gratings (FBGs) to interleave two fiber Michelson interferometers which share almost the same part of the main optical path. One of the fiber interferometers is used to stabilize the system, employing an electronic feedback loop to drive a piezoelectric actuator to tune the optical path of the reference beam in order to keep the interferometer in quadrature state. By this way, the low frequency drifts in the phase of the interferometric signals which are resulted from environmental disturbances are compensated for. The other one is used to perform the measurement task. By employing the characteristics of 3dB-coupler, the interferometric signals from the two outputs of the 3dB-couper are 180º out of phase. The two interferometric signals are input into an electronic processor and convert into currents, which are linear to the power of the optical interferometric light. The signals are collected by NI USB-5132 acquisition card and processed by a program in a personal computer. The measurement system is configured with fiber and fiber components which are integrated together. As the cutoff frequency of the feedback loop is 1.5Hz, the measurement system is capable of measuring vibration with frequencies bigger than 1.5Hz and the amplitude of the measured vibration is not limited.

  2. Low crosstalk Arrayed Waveguide Grating with Cascaded Waveguide Grating Filter

    Energy Technology Data Exchange (ETDEWEB)

    Deng Yang; Liu Yuan; Gao Dingshan, E-mail: dsgao@mail.hust.edu.cn [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2011-02-01

    We propose a highly compact and low crosstalk arrayed waveguide grating (AWG) with cascaded waveguide grating (CWGF). The side lobes of the silicon nanowire AWG, which are normally introduced by fabrication errors, can be effectively suppressed by the CWGF. And the crosstalk can be improved about 15dB.

  3. Stretchable diffraction gratings for spectrometry

    NARCIS (Netherlands)

    Simonov, A.N.; Grabarnik, S.; Vdovine, G.V

    2007-01-01

    We have investigated the possibility of using transparent stretchable diffraction gratings for spectrometric applications. The gratings were fabricated by replication of a triangular-groove master into a transparent viscoelastic. The sample length, and hence the spatial period, can be reversibly cha

  4. Picosecond Holographic-Grating Spectroscopy

    NARCIS (Netherlands)

    Duppen, K.

    1987-01-01

    Interfering light waves produce an optical interference pattern in any medium that interacts with light. This modulation of some physical parameter of the system acts as a classical holographic grating for optical radiation. When such a grating is produced through interaction of pulsed light waves w

  5. Grating-based red lasers

    Science.gov (United States)

    Pezeshki, Bardia; Hagberg, Mats; Zelinski, Michael; Zou, Sarah; Kolev, Emil I.

    1999-04-01

    We have demonstrated a number of high power and single- frequency lasers at 635 - 680 nm by incorporating a grating reflector within the device, including DBRs, tunable DBRs, monolithic MOPAs, DFBs, and angled-grating DFBs. The DBR laser, with an unpumped grating as the rear reflector, is the simplest single-frequency structure, with about 20 mW output power. The device can be tuned about 3 nm by injecting current in the rear grating. Higher output power can be obtained by combining the DBR with a flared amplifier to form a monolithic MOPA with over 250 mW CW output power. Unlike DBR structures, the DFBs have a grating throughout their gain region, and therefore show no mode hops. Wavelengths as short as 634 nm and output powers as high as 90 mW have been obtained with DFBs. An angle-grating DFB is a broad area device where the angled grating forces lasing in a single spatial and longitudinal mode. More than 400 mW in single-frequency power has been obtained at 660 nm from such a structure. In general, grating-based red lasers are useful for interferometry, spectroscopy, and fiber-coupling applications.

  6. Slow plasmons in grating cavities

    Science.gov (United States)

    Aydinli, Atilla; Karademir, Ertugrul; Balci, Sinan; Kocabas, Coskun

    2016-03-01

    Recent research on surface plasmon polaritons and their applications have brought forward a wealth of information and continues to be of interest to many. In this report, we concentrate on propagating surface plasmon polaritons (SPPs) and their interaction with matter. Using grating based metallic structures, it is possible to control the electrodynamics of propagating SPPs. Biharmonic gratings loaded with periodic Si stripes allow excitation of SPPs that are localized inside the band gap with grating coupling. The cavity state is formed due to periodic effective index modulation obtained by one harmonic of the grating and loaded Si stripes. More complicated grating structures such as metallic Moiré surfaces have also been shown to form a localized state inside the band gap when excited with Kretschmann configuration.

  7. Near-field probing of photonic crystal directional couplers

    DEFF Research Database (Denmark)

    Volkov, V. S.; Bozhevolnyi, S. I.; Borel, Peter Ingo

    2006-01-01

    . By comparing the near-field optical images recorded in and after the directional coupler area, the features of light distribution are analyzed. Finally, the scanning near-field optical microscope observations are found to be in agreement with the transmission measurements conducted with the same sample.......We report the design, fabrication and characterization of a photonic crystal directional with a size of ~20 x 20 mm2 fabricated in silicon-on-insulator material. Using a scanning near-field optical microscope we demonstrate a high coupling efficiency for TM polarized light at telecom wavelengths...

  8. Directional Nanoslit-Bump Coupler for Surface Plasmon Polaritons

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yong-Liang; ZHAO De-Yin; ZHOU Chuan-Hong; JIANG Xun-Ya

    2008-01-01

    We investigate a p-polarized plane wave transmitted through a metallic slit-bump nanostructure using the finite difference time domain simulation.It is found that narrow bumps with suitable separation can diffract surface plasmons into highly directional collimating beams,The number and directionality of the beams can be controlled by adjusting the geometry parameters of the nanostructure.The structure with optimized parameters may be interesting for practical applications as directional nanoslit SPP-light coupler in integrated photonic devices.

  9. Fabrication of optical filters based on polymer asymmetric Bragg couplers.

    Science.gov (United States)

    Chuang, Wei-Ching; Lee, An-Chen; Chao, Ching-Kong; Ho, Chi-Ting

    2009-09-28

    In this work, we successfully developed a process to fabricate dual-channel polymeric waveguide filters based on an asymmetric Bragg coupler (ABC) using holographic interference techniques, soft lithography, and micro molding. At the cross- and self-reflection Bragg wavelengths, the transmission dips of approximately -16.4 and -11.5 dB relative to the 3 dB background insertion loss and the 3 dB transmission bandwidths of approximately 0.6 and 0.5 nm were obtained from an ABC-based filter. The transmission spectrum overlaps when the effective index difference between two single waveguides is less than 0.002.

  10. Acoustic coupler for acquisition of coronary artery murmurs

    DEFF Research Database (Denmark)

    Zimmermann, Niels Henrik; Schmidt, Samuel; Hansen, John;

    2011-01-01

    in a clinical trial including 463 patients referred for elective coronary angiography. The preliminary results show, that it was possible to record heart sound in the diastolic period with a sound pressure level approximately 30 dB above the noise floor of the microphone and recording system in the frequency......The aim of the study was to design and evaluate a coupler/ microphone system for recording weak murmurs from stenoses in the coronar artery. The suggested design is based on the use of a high quality microphone, coupled to the chest through a small air cavity. Since the determination of the exact...

  11. Experimental Characterisation of Moreno Cross Slot Couplers for Blass Matrix Design

    Directory of Open Access Journals (Sweden)

    K. Jery Varghese

    1998-10-01

    Full Text Available This paper presents the experimental characterisation of Moreno cross-slot coupler which is the basic building block of multiple beam forming network (Blass matrix. The lack of exact theory of such coupler requires extensive experimental evaluation. A novel test jig has been designed, fabricated and tested for this purpose. The experimental results for different scattering parameters are presented.

  12. Ultra-low loss nano-taper coupler for Silicon-on-Insulator ridge waveguide

    DEFF Research Database (Denmark)

    Pu, Minhao; Liu, Liu; Ou, Haiyan;

    2010-01-01

    A nano-taper coupler is optimized specially for the transverse-magnetic mode for interfacing light between a silicon-on-insulator ridge waveguide and a single-mode fiber. An ultra-low coupling loss of ~0.36dB is achieved for the nano-taper coupler....

  13. Raman probes based on optically-poled double-clad fiber and coupler

    DEFF Research Database (Denmark)

    Brunetti, Anna Chiara; Margulis, Walter; Rottwitt, Karsten

    2012-01-01

    of a sample of dimethyl sulfoxide (DMSO), when illuminating the waveguide with 1064nm laser light. The Raman signal is collected in the inner cladding, from which it is retrieved with either a bulk dichroic mirror or a double-clad fiber coupler. The coupler allows for a substantial reduction of the fiber...

  14. Low insertion loss SOI microring resonator integrated with nano-taper couplers

    DEFF Research Database (Denmark)

    Pu, Minhao; Frandsen, Lars Hagedorn; Ou, Haiyan;

    2009-01-01

    We demonstrate a microring resonator working at TM mode integrated with nano-taper couplers with 3.6dB total insertion loss. The measured insertion loss of the nano-taper coupler was only 1.3dB for TM mode....

  15. Gain characteristics of quantum dot fiber amplifier based on asymmetric tapered fiber coupler

    DEFF Research Database (Denmark)

    Guo, Hairun; Pang, Fufei; Zeng, Xianglong

    2013-01-01

    We theoretically analyzed the gain characteristics of an integrated semiconductor quantum dot (QD) fiber amplifier (SQDFA) by using a 2×2 tapered fiber coupler with a PbS QD-coated layer. The asymmetric structure of the fiber coupler is designed to have a maximum working bandwidth around 1550-nm...

  16. Hybrid Optical Comb Filter with Multi-Port Fiber Coupler for DWDM Optical Network

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Optical comb filters based on multi-port fused fiber couplers are proposed and numerically analyzed, 3-arm MZI composed by 1×7 fiber splitter and 3×3 fiber coupler, and 2-stage cascaded FIR type MZI interleave filter.

  17. Nonlinear modal propagation analysis method in multimode interference coupler for operation development

    Science.gov (United States)

    Tajaldini, Mehdi; Mat Jafri, Mohd Zubir Mat

    2013-05-01

    In this study, we propose a novel approach that is called nonlinear modal propagation analysis method (NMPA) in MMI coupler via the enhances of nonlinear wave propagation in terms of guided modes interferences in nonlinear regimes, such that the modal fields are measurable at any point of coupler and output facets. Then, the ultra-short MMI coupler is optimized as a building block in micro ring resonator to investigate the method efficiency against the already used method. Modeling results demonstrate more efficiency and accuracy in shorter lengths of multimode interference coupler. Therefore, NMPA can be used as a method to study the compact dimension coupler and for developing the performance in applications. Furthermore, the possibility of access tothe all-optical switching is assumed due to one continuous MMI for proof of the development of performances in nonlinear regimes.

  18. Note: Compact optical fiber coupler for diamond anvil high pressure cells

    Science.gov (United States)

    Pugh, E.

    2013-10-01

    A compact optical fiber coupler has been developed to allow transmission of light through an optical fiber to and from the high pressure region of a diamond anvil high pressure cell. Despite its small size the coupler has focusing adjustments and optics, which allows the light to be focused precisely on the sample within the pressure cell. The coupler is suitable for a wide range of optical measurements and particularly for high pressure measurements at low temperatures in cryostats with no optical windows. The use of the coupler to determine the pressure in a diamond anvil cell at 1.2 K using the ruby fluorescence spectra of ruby is demonstrated. The small size of the coupler and its construction out of nonmagnetic beryllium copper makes it suitable for use in high magnetic fields and for magnetization experiments.

  19. Experimental study of nonlinear switching characteristics of conventional 2 × 2 fused tapered couplers

    Institute of Scientific and Technical Information of China (English)

    Feng Liu; Qing Ye; Aiping Luo; Jianrong Qiu; Congshan Zhu; Ronghui Qu; Zujie Fang

    2005-01-01

    The nonlinear switching characteristics of fused fiber directional couplers were studied experimentally. By using femtosecond laser pulses with pulse width of 100 fs and wavelength of about 1550 nm from a system of Ti:sapphire laser and optical parametric amplifier (OPA), the nonlinear switching properties of a null coupler and a 100% coupler were measured. The experimental results were coincident with the simulations based on nonlinear propagation equations in fiber by using super-mode theory. Nonlinear loss in fiber was also measured to get the injected power at the coupler. After deducting the nonlinear loss and input efficiency, the nonlinear switching critical peak powers for a 100% and a null fused couplers were calculated to be 9410 and 9440 W, respectively. The nonlinear loss parameter PN in an expression of αNL = αP/PN was obtained to be PN = 0.23 W.

  20. Stop band characteristics of a TESLA cavity coaxial-type HOM coupler

    Institute of Scientific and Technical Information of China (English)

    WANG Er-Dong; WANG Fang; ZHANG Bao-Cheng; S.Noguchi; K.Watanabe; ZHAO Kui

    2009-01-01

    A TTF-type coaxial higher order modes (HOM) coupler has been used in a TESLA 9 cell cavity. It is impossible to measure the stop band characteristics of the HOM coupler with the cavity. A measurement device for the coaxial transmission line type for the HOM coupler has been designed at Peking University. Experimentally it was shown that the average voltage standing wave ratio of the coaxial transmission line is smaller than 1.08. The experimental results of the stop band characteristics of the TTF-type HOM coupler have been fitted for the simulation. This paper describes the design of the measurement device and discusses the experimental and simulation results of stop band characteristics of the HOM coupler.

  1. Temperature Dependence of Characteristics for Multimode Interference Based 3-dB Coupler in SOI

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The temperature dependence of characteristics for multimode interference(MMI) based 3-dB coupler in silicon-on-insulator is analyzed, which originates from the relatively high thermo-optic coefficient of silicon. For restricted interference 3-dB MMI coupler, the output power uniformity is ideally 0 at room temperature and becomes 0.32dB when temperature rises up to 550K.For symmetric interference 3-dB MMI coupler, the power uniformity keeps ideally 0 due to its intrinsic symmetric interference mechanism. With the temperature rising, the excess loss of the both devices increases. The performance deterioration due to temperature variety is more obvious to restricted interference MMI 3-dB coupler, comparing with that of symmetric interference MMI 3-dB coupler.

  2. MINIATURIZED MICROSTRIP BRANCH-LINE COUPLER WITH GOOD HARMONIC SUPPRESSION PERFORMANCE

    Institute of Scientific and Technical Information of China (English)

    Yang Guo; Li Bo; Kang Wei; Ge Sheng

    2012-01-01

    This paper presents a miniaturized microstrip branch-line coupler with good harmonic suppression performance.The proposed coupler consists of four branch-line sections,each of which is loaded by open-circuit stubs both at the center and the two ends.This type of loading can realize size reduction and harmonic suppression.As an example,a proposed branch-line coupler operating at 1.0 GHz is designed,fabricated and measured.The results show that the proposed branch-line coupler occupies 67% size of a conventional one and has better than 20 dB suppression from 1.9 to 5.8 GHz.Furthermore,the high slop of the transition band ensures good selectivity of the coupler.

  3. Stabilizing mechanism and running behavior of couplers on heavy haul trains

    Science.gov (United States)

    Xu, Ziqiang; Wu, Qing; Luo, Shihui; Ma, Weihua; Dong, Xiaoqing

    2014-11-01

    Published studies in regard to coupler systems have been mainly focused on the manufacturing process or coupler strength issues. With the ever increasing of tonnage and length of heavy haul trains, lateral in-train forces generated by longitudinal in-train forces and coupler rotations have become a more and more significant safety issue for heavy haul train operations. Derailments caused by excessive lateral in-train forces are frequently reported. This article studies two typical coupler systems used on heavy haul locomotives. Their structures and stabilizing mechanism are analyzed before the corresponding models are developed. Coupler systems models are featured by two distinct stabilizing mechanism models and draft gear models with hysteresis considered. A model set which consists of four locomotives and three coupler systems is developed to study the rotational behavior of different coupler systems and their implications for locomotive dynamics. Simulated results indicate that when the locomotives are equipped with the type B coupler system, locomotives can meet the dynamics standard on tangent tracks; while the dynamics performance on curved tracks is very poor. The maximum longitudinal in-train force for locomotives equipped with the type B coupler system is 2000 kN. Simulations revealed a distinct trend for the type A coupler system. Locomotive dynamics are poorer for the type A case when locomotives are running on tangent tracks, while the dynamics are better for the type A case when locomotives are running on curved tracks. Theoretical studies and simulations carried out in this article suggest that a combination of the two types of stabilizing mechanism can result in a good design which can significantly decrease the relevant derailments.

  4. Stabilizing Mechanism and Running Behavior of Couplers on Heavy Haul Trains

    Institute of Scientific and Technical Information of China (English)

    XU Ziqiang; WU Qing; LUO Shihui; MA Weihua; DONG Xiaoqing

    2014-01-01

    Published studies in regard to coupler systems have been mainly focused on the manufacturing process or coupler strength issues. With the ever increasing of tonnage and length of heavy haul trains, lateral in-train forces generated by longitudinal in-train forces and coupler rotations have become a more and more significant safety issue for heavy haul train operations. Derailments caused by excessive lateral in-train forces are frequently reported. This article studies two typical coupler systems used on heavy haul locomotives. Their structures and stabilizing mechanism are analyzed before the corresponding models are developed. Coupler systems models are featured by two distinct stabilizing mechanism models and draft gear models with hysteresis considered. A model set which consists of four locomotives and three coupler systems is developed to study the rotational behavior of different coupler systems and their implications for locomotive dynamics. Simulated results indicate that when the locomotives are equipped with the type B coupler system, locomotives can meet the dynamics standard on tangent tracks; while the dynamics performance on curved tracks is very poor. The maximum longitudinal in-train force for locomotives equipped with the type B coupler system is 2000 kN. Simulations revealed a distinct trend for the type A coupler system. Locomotive dynamics are poorer for the type A case when locomotives are running on tangent tracks, while the dynamics are better for the type A case when locomotives are running on curved tracks. Theoretical studies and simulations carried out in this article suggest that a combination of the two types of stabilizing mechanism can result in a good design which can significantly decrease the relevant derailments.

  5. RF coupler for high-power CW FEL photoinjector

    Energy Technology Data Exchange (ETDEWEB)

    Kurennoy, S. (Sergey); Young, L. M. (Lloyd M.)

    2003-01-01

    A high-current emittance-compensated RF photoinjector is a key enabling technology for a high-power CW FEL. The design presently under way is a 100-mA 2.5-cell {pi}-mode, 700-MHz, normal conducting demonstration CW RF photoinjector. This photoinjector will be capable of accelerating 3 nC per bunch with an emittance at the wiggler less than 10 mm-mrad. The paper presents results for the RF coupling from ridged wave guides to hte photoinjector RF cavity. The LEDA and SNS couplers inspired this 'dog-bone' design. Electromagnetic modeling of the coupler-cavity system has been performed using both 2-D and 3-D frequency-domain calculations, and a novel time-domain approach with MicroWave Studio. These simulations were used to adjust the coupling coefficient and calculate the power-loss distribution on the coupling slot. The cooling of this slot is a rather challenging thermal management project.

  6. Switchable Bragg gratings

    DEFF Research Database (Denmark)

    Marckmann, Carl Johan

    2003-01-01

    The subject of this ph.d. thesis was the development of an electrically switchable Bragg grating made in an optical waveguide using thermal poling to be applied within optical telecommunication systems. The planar waveguides used in this thesis were fabricated at the Micro- and Nanotechnology....... This result is very useful in the production of telecommunication devices since polarization independence of the second-order nonlinearity is wanted. In order to increase the second-order nonlinearity, it was found that the introduction of a high refractive index trapping layer was favorable. During...... the thesis, the thermal poling induced second-order nonlinearity was increased by approximately 64% making a silica based optical switch possible. Finally, a possible explanation to the very high, but short-lived, poling results obtained by some groups was discovered....

  7. Optical Fiber Grating based Sensors

    DEFF Research Database (Denmark)

    Michelsen, Susanne

    2003-01-01

    In this thesis differenct optical fiber gratings are used for sensor purposes. If a fiber with a core concentricity error (CCE) is used, a directional dependent bend sensor can be produced. The CCE direction can be determined by means of diffraction. This makes it possible to produce long......-period gratings in a fiber with a CCE direction parallel or perpendicular to the writing direction. The maximal bending sensitivity is independent on the writing direction, but the detailed bending response is different in the two cases. A temperature and strain sensor, based on a long-period grating and two...

  8. Measuring the performance of the coaxial HOM coupler on a 2-cell TESLA-shape copper cavity

    Institute of Scientific and Technical Information of China (English)

    WANG Fang; WANG Er-Dong; ZHANG Bao-Cheng; ZHAO Kui

    2009-01-01

    Coaxial High Order Mode (HOM) couplers have been fabricated at Peking University and their RF performance has been measured on a test device consisting of a coaxial transmission line and a 2-cellTESLA-shape copper cavity. The test results on the 2-cell TESLA-shape copper cavity with HOM couplers indicate that the coupler can cut off the fundamental mode TM010 and absorb HOMs effectively after a careful adjustment. The optimal angle of the HOM coupler with the beam tube is found. The initial test results of HOM couplers are presented in this paper.

  9. Extreme Silica Optical Fibre Gratings

    Directory of Open Access Journals (Sweden)

    Kevin Cook

    2008-10-01

    Full Text Available A regenerated optical fibre Bragg grating that survives temperature cycling up to 1,295°C is demonstrated. A model based on seeded crystallisation or amorphisation is proposed.

  10. Hollow-core grating fiber

    Science.gov (United States)

    Barillé, R.; Tajalli, P.; Roy, P.; Ahmadi-kandjani, S.; Kucharski, S.; Ortyl, E.

    2012-02-01

    We propose a new type of hollow-core fiber where the propagation is ensured by a photoinduced self-pattern acting as a surface relief grating (SRG). The SRG is written by launching a suitable laser beam with proper polarization in a capillary glass fiber with the inner surface previously coated with an azopolymer thin film. Such a grating acts as a wavelength/angle dependant reflective mirror and enhances the confinement and the propagation of the light.

  11. MEMS Bragg grating force sensor

    DEFF Research Database (Denmark)

    Reck, Kasper; Thomsen, Erik Vilain; Hansen, Ole

    2011-01-01

    We present modeling, design, fabrication and characterization of a new type of all-optical frequency modulated MEMS force sensor based on a mechanically amplified double clamped waveguide beam structure with integrated Bragg grating. The sensor is ideally suited for force measurements in harsh...... environments and for remote and distributed sensing and has a measured sensitivity of -14 nm/N, which is several times higher than what is obtained in conventional fiber Bragg grating force sensors. © 2011 Optical Society of America....

  12. Analysis and Design of Three-Line Microstrip Couplers on Anisotropic Substrates

    Science.gov (United States)

    Yu, Lukang

    The behavior of guided modes and their associated properties of three-line microstrip couplers on anisotropic substrates are investigated in this dissertation. The wave propagation on these lines is described by three normal modes modified by the mutual coupling between the lines under the quasi-TEM assumption. The conditions for the equalization of the mode impedances and phase velocities, and the matching and isolation of the coupler ports are derived using the normal-mode characteristics and six-port scattering parameters. The use of dielectric anisotropy is suggested as a means to improve the coupler directivity degraded by the structural inhomogeneity. Analytical results based on the coupled-mode formulation are summarized. The Green's function for the microstrip configuration is derived to transform an anisotropic problem into an isotropic problem. The normal-mode characteristics of the coupler are determined from the structural capacitances. Effects due to strip -thickness, loss and dispersion are dealt with. The design equations for symmetrical lines are derived. The existence of an ideal six-port directional coupler is proved and the singular behavior of the normal-mode parameters occurring at the critical point of coupling-coefficient equalization is examined. Typical applications of three-line microstrip couplers in microwave integrated circuits are discussed with simulation results. Experimental results of a coupler fabricated on an Epsilam-10 substrate are presented for the verification of the theoretical findings.

  13. Stretchable diffraction gratings for spectrometry.

    Science.gov (United States)

    Simonov, Aleksey N; Grabarnik, Semen; Vdovin, Gleb

    2007-07-23

    We have investigated the possibility of using transparent stretchable diffraction gratings for spectrometric applications. The gratings were fabricated by replication of a triangular-groove master into a transparent viscoelastic. The sample length, and hence the spatial period, can be reversibly changed by mechanical stretching. When used in a monochromator with two slits, the stretchable grating permits scanning the spectral components over the output slit, converting the monochromator into a scanning spectrometer. The spectral resolution of such a spectrometer was found to be limited mainly by the wave-front aberrations due to the grating deformation. A model relating the deformation-induced aberrations in different diffraction orders is presented. In the experiments, a 12-mm long viscoelastic grating with a spatial frequency of 600 line pairs/mm provided a full-width at half-maximum resolution of up to ~1.2 nm in the 580-680 nm spectral range when slowly stretched by a micrometer screw and ~3 nm when repeatedly stretched by a voice coil at 15 Hz. Comparison of aberrations in transmitted and diffracted beams measured by a Shack- Hartmann wave-front sensor showed that astigmatisms caused by stretch-dependent wedge deformation are the main factors limiting the resolution of the viscoelastic-grating-based spectrometer.

  14. HF power couplers for pulsed superconducting cavity resonators; Coupleurs de puissance HF pour cavites supraconductrices en mode pulse

    Energy Technology Data Exchange (ETDEWEB)

    Jenhani, Hassen [Laboratoire de l' Accelerateur Lineaire, IN2P3-CNRS et Universite de Paris-Sud, BP 34, F-91898 Orsay Cedex (France)

    2006-11-15

    Recent years have seen an impressive improvement in the accelerating gradients obtained in superconducting cavities. Consequently, such cavities have become attractive candidates for large superconducting linear accelerator projects such as the European XFEL and the International Linear Collider (ILC). As a result, there is a strong interest in reducing RF conditioning time and improving the performance of the input power couplers for these cavities. The so-called TTF-III input power coupler, adopted for the XFEL superconducting RF cavities are complex components. In order to better understand the behavior of this component we have performed a series of experiments on a number of such couplers. Initially, we developed a fully automated RF high power test stand for coupler conditioning procedure. Following this, we performed a series of coupler conditioning tests. This has allowed the study of the coupler behavior during processing. A number of experiments were carried out to evaluate the in-situ baking effect on the conditioning time. Some of the conditioned couplers were sent to DESY in order to be tested on 9-cells TESLA cavities under cryogenic conditions. These tests have shown that the couplers in no way limit the cavity performance, even up to gradients of 35 MV/m. The main objective of our coupler studies was the reduction of their conditioning time, which represents one of the most important criteria in the choice of coupler for high energy linacs. Excellent progress in reducing the conditioning time has been demonstrated by making appropriate modifications to the conditioning procedure. Furthermore, special attention was paid to electron generation processes in the couplers, via multipacting. Simulations of this process were made on both the TTF-III coupler and on a new coupler prototype, TTF-V. Experiments aimed at suppressing multipacting were also successfully achieved by using a DC bias on the inner conductor of the co-axial coupler. (author)

  15. Optical trimer: A theoretical physics approach to waveguide couplers

    CERN Document Server

    Stoffel, A; Rodríguez-Lara, B M

    2016-01-01

    We study electromagnetic field propagation through an ideal, passive, triangular three-waveguide coupler using a symmetry based approach to take advantage of the underlying $SU(3)$ symmetry. The planar version of this platform has proven valuable in photonic circuit design providing optical sampling, filtering, modulating, multiplexing, and switching. We show that a group-theory approach can readily provide a starting point for design optimization of the triangular version. Our analysis is presented as a practical tutorial on the use of group theory to study photonic lattices for those not familiar with abstract algebra methods. In particular, we study the equilateral trimer to show the relation of pearl-necklace arrays with the Discrete Fourier Transform due to their cyclic group symmetry, and the isosceles trimer to show its relation with the golden ratio and its ability to provide stable output at a single waveguide. We also study the propagation dependent case of an equilateral trimer that linearly increa...

  16. Single-mode fibre coupler as refractometer sensor

    Indian Academy of Sciences (India)

    Pabitra Nath; Mridul Buragohain

    2012-12-01

    We report a simple, non-intrusive fibre-optic refractometer sensor for measuring the refractive index of liquid and optically transparent solid medium. Sensing principle of the proposed sensor is based on monitoring the back-reflected light signal through the second input port of a 2 × 1 single-mode fibre coupler when light signal from the output port is focussed at the interface of air and a liquid or solid medium and back-reflected exactly along the same path. Depending on the refractive index of the medium, the amount of back-reflected intensity would vary and in the present work we exploit this principle to measure the refractive index of an optically transparent medium. Variation of refractive index as small as 0.001 RIU can be measured with our proposed sensor.

  17. Modulation instability of dispersion-shifted fiber couplers

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yan-yong; JIA Wei-guo; HAN Ying-ming; YING Chun; BAO Hong-mei

    2008-01-01

    The nonlinear coupled-mode equations are rewritten by even and odd modes. We study modulation instability (MI) of dispersion-shifted fiber couplers when either even or odd mode is launched alone by using zero-dispersion waveleng threlatively long (quasi-cw) pulses. The result shows that there are new types of MI in both the normal-dispersion and the anomalous-dispersion regimes. MI is concerned with forth-order dispersion and has no relation with third-order dispersion.Quasi-cw can be changed into pulses array under certain conditions. We can extract super short pulse from this. Furthermore,the bandwidth of gain spectra widens and its strength accretes as the input power increases.

  18. Hybrid fiber resonator employing LRSPP waveguide coupler for gyroscope

    Science.gov (United States)

    Qian, Guang; Fu, Xing-Chang; Zhang, Li-Jiang; Tang, Jie; Liu, Yi-Ran; Zhang, Xiao-Yang; Zhang, Tong

    2017-01-01

    Polarization error and temperature noise are two main limits to the performance of resonant fiber optic gyroscope (RFOG). To overcome these limits, we demonstrated a hybrid resonator consisting of a polymer-based long-range surface plasmon polariton (LRSPP) waveguide coupler and a silica fiber. Single-polarization property of LRSPP waveguide and the offsetting of the opposite thermo-optical characteristics between the polymer-based LRSPP waveguide and the silica fiber can effectively inhibit both the polarization error and the temperature noise of RFOG. The measured resonance spectrum of the hybrid resonator shows the absence of polarization noise. The temperature dependence of wavelength shift (TDWS) of resonator dropped to about 2 pm/°C, or even to 0 pm/°C with optimal structure, which dramatically improves the temperature stability of gyroscope system. In addition, the hybrid resonator also shows tremendous application potential in rate-grade and tactical-grade gyroscopes. PMID:28117412

  19. Development of Fundamental Power Coupler for C-ADS Superconducting Elliptical cavities

    CERN Document Server

    Gu, Kui-Xiang; Pan, Wei-Min; Huang, Tong-Ming; Ma, Qiang; Meng, Fan-Bo

    2016-01-01

    5-cell elliptical cavities are chosen for the main linac of China Accelerator Driven sub-critical System in the medium energy section. Each cavity is driven by one fundamental power coupler delivering RF power up to 150 kW. A single window, coaxial type coupler satisfying high power requirements, class 10 clean room assembly with cavity and low heat load simultaneously was designed. This paper gives the details of RF design, external Q calculation and thermal analysis as well as multipacting simulations of the coupler.

  20. Carbon dioxide laser fabrication of fused-fiber couplers and tapers.

    Science.gov (United States)

    Dimmick, T E; Kakarantzas, G; Birks, T A; Russell, P S

    1999-11-20

    We report the development of a fiber taper and fused-fiber coupler fabrication rig that uses a scanning, focused, CO(2) laser beam as the heat source. As a result of the pointlike heat source and the versatility associated with scanning, tapers of any transition shape and uniform taper waist can be produced. Tapers with both a linear shape and an exponential transition shape were measured. The taper waist uniformity was measured and shown to be better than +/-1.2%. The rig was also used to make fused-fiber couplers. Couplers with excess loss below -0.1 dB were routinely produced.

  1. Switching of transmission resonances in a two-channels coupler: A Boundary Wall Method scattering study

    Science.gov (United States)

    Nunes, A.; Zanetti, F. M.; Lyra, M. L.

    2016-10-01

    In this work, we study the transmission characteristics of a two-channels coupler model system using the Boundary Wall Method (BWM) to determine the solution of the corresponding scattering problem of an incident plane wave. We show that the BWM provides detailed information regarding the transmission resonances. In particular, we focus on the case of single channel input aiming to explore the energy switching performance of the coupler. We show that the coupler geometry can be tailored to allow for the first transmission resonances to be predominantly transmitted on specific output channels, an important characteristic for the realization of logical operations.

  2. ANSYS modeling of thermal contraction of SPL HOM couplers during cool-down

    CERN Document Server

    Papke, K

    2016-01-01

    During the cool-down the HOM coupler as well as the cavity inside the cryo module experience a thermal contraction. For most materials between room temperature and liquid helium temperatures, the changes in dimension are in the order of a few tenths of a percent change in volume. This paper presents the effect of thermal contraction on the RF transmission behavior of HOM couplers, and in particular the influence on its notch filter. Furthermore the simulation process with APDL is explained in detail. Conclusions about the necessary tuning range of the notch filter are made which is especially a concern for couplers with only notch filter.

  3. Grating-flanked plasmonic coaxial apertures for efficient fiber optical tweezers.

    Science.gov (United States)

    Saleh, Amr A E; Sheikhoelislami, Sassan; Gastelum, Steven; Dionne, Jennifer A

    2016-09-05

    Subwavelength plasmonic apertures have been foundational for direct optical manipulation of nanoscale specimens including sub-100 nm polymeric beads, metallic nanoparticles and proteins. While most plasmonic traps result in two-dimensional localization, three-dimensional manipulation has been demonstrated by integrating a plasmonic aperture on an optical fiber tip. However, such 3D traps are usually inefficient since the optical mode of the fiber and the subwavelength aperture only weakly couple. In this paper we design more efficient optical-fiber-based plasmonic tweezers combining a coaxial plasmonic aperture with a plasmonic grating coupler at the fiber tip facet. Using full-field finite difference time domain analysis, we optimize the grating design for both gold and silver fiber-based coaxial tweezers such that the optical transmission through the apertures is maximized. With the optimized grating, we show that the maximum transmission efficiency increases from 2.5% to 19.6% and from 1.48% to 16.7% for the gold and silver structures respectively. To evaluate their performance as optical tweezers, we calculate the optical forces and the corresponding trapping potential on dielectric particles interacting with the apertures. We demonstrate that the enahncement in the transmission translates into an equivalent increase in the optical forces. Consequently, the optical power required to achieve stable optical trapping is significantly reduced allowing for efficient localization and 3D manipulation of sub-30 nm dielectric particles.

  4. Efficient iterative technique for designing bragg gratings

    DEFF Research Database (Denmark)

    Plougmann, Nikolai; Kristensen, Martin

    2004-01-01

    We present a new iterative method for designing Bragg gratings based on the Levenberg-Marquardt method of minimizing a chi-squared merit function. It is effective for designing both weak and strong gratings and is particularly well suited for unchirped gratings.......We present a new iterative method for designing Bragg gratings based on the Levenberg-Marquardt method of minimizing a chi-squared merit function. It is effective for designing both weak and strong gratings and is particularly well suited for unchirped gratings....

  5. Engineering Study of Crab Cavity HOM Couplers for LHC High Luminosity Upgrade

    CERN Document Server

    Park, Hyekyung; Delayen, Jean Roger; De Silva, S U; Li, Z; Nicol, T H; Capelli, Teddy; Templeton, Niklas John

    2015-01-01

    The LHC is planning to employ crab cavities for the high luminosity upgrade. Old Dominion University and SLAC National Laboratory are developing a crab cavity completed with the HOM damping couplers [1]. The HOM couplers are coaxial type and perform over broadband up to 2 GHz. The amount of extracted power requires active cooling using liquid helium. The electromagnetic study has provided expected power dissipation on the coupler. Correlations between the fabrication tolerance and its damping performance have been studied and the results are providing guidelines on how to manufacture the HOM couplers. This paper summarizes the engineering studies; mechanical strength as a part of pressure system, thermal stability, and fabrication method to ensure the required tolerance.

  6. Optical Code Generating Device Using 1×N Asymmetric Hollow Waveguide Couplers

    Institute of Scientific and Technical Information of China (English)

    Abang Annuar EHSAN; Sahbudin SHAARI; Mohd Kamil ABD.RAHMAN; Kee Mohd Rafique KEE ZAINAL ABIDIN

    2008-01-01

    An optical code generating device for security access system application is presented. The code generating device constructed using asymmetric hollow optical waveguide coupler design provides a unique series of output light intensities which are successively used as an optical code. The design of the waveguide is made using two major components which are asymmetric Y-junction splitter and a linear taper. Waveguiding is done using a hollow waveguide structure. Construction of higher level 1×N hollow waveguide coupler is done utilizing a basic 1×2 asymmetric waveguide coupler design together with a cascaded design scheme. Non-sequential ray tracing of the asymmetric hollow optical waveguide couplers is performed to predict the optical transmission properties of the waveguide. A representation of the code combination that can be generated from the device is obtained using combinatory number theory.

  7. Conceptual Design Of An Ideal Variable Coupler For Superconducting Radiofrequency 1.3GHz Cavities

    CERN Document Server

    Xu, Chen

    2014-01-01

    Inspired by the development of over-moded RF component as an undulator, we explored another over-moded structure that could serve the variable coupling for SRF purpose. This application is to fulfill variation of S11 from 0 to -20db with CW power of 7 KW. The static heat loss in the coupler is trivial from calculation. An advantage of this coupler is that the thermal isolation between the 2K and 300K section is considerable by vacuum separation. Within this coupler, only a single propagation mode is allowed at each section, and thus, the fact that no energy is converted to high order mode bring almost full match without loss. The analytical and numerical calculation for a two window variable coupler is designed and optimized. A RF power variation is illustrated in the scattering matrix and coupling to cavity is also discussed.

  8. Switching dynamics of a two-dimensional nonlinear couplers in a photopolymer – A variational approach

    Indian Academy of Sciences (India)

    T Uthayakumar; K Porsezian

    2010-11-01

    We study the optical switching of the two-dimensional nonlinear coupler in a doped photopolymer. The coupled nonlinear Schrödinger equations (CNLSEs) describing our coupler system are analysed using Lagrangian variational method. From the Lagrangian, a set of coupled ordinary differential equations (ODEs) describing the system dynamics is obtained. This set of ODE’s is further reduced to single coupled equation and an analytical solution is obtained using the cnoidal functions and the system dynamics is studied. The key factor for switching mechanism of our coupler system is the metal-induced surface plasmon resonance (SPR). This SPR-induced local nonlinear effects results in self-focussing of the optical beam through the launched core. A description of a particle in a well is also made to study the photon switching through the coupler system.

  9. Fast surrogate-assisted simulation-driven optimization of compact microwave hybrid couplers

    Science.gov (United States)

    Kurgan, Piotr; Koziel, Slawomir

    2016-07-01

    This work presents a robust methodology for expedited simulation-driven design optimization of compact microwave hybrid couplers. The technique relies on problem decomposition, and a bottom-up design strategy, starting from the level of basic building blocks of the coupler, and finishing with a tuning procedure that exploits a fast surrogate model of the entire structure. The latter is constructed by cascading local response surface approximations of coupler elementary elements. The cross-coupling effects within the structure are neglected in the first stage of the design process; however, they are accounted for in the tuning phase by means of space-mapping correction of the surrogate. The proposed approach is demonstrated through the design of a compact rat-race and two branch-line couplers. In all cases, the computational cost of the optimization process is very low and corresponds to just a few high-fidelity electromagnetic simulations of respective structures. Experimental validation is also provided.

  10. Design of a Compact X-Band Substrate Integrated Waveguide Directional Coupler

    Directory of Open Access Journals (Sweden)

    B. H. Ahmad

    2013-04-01

    Full Text Available This paper presented the design of four-port network directional coupler at X-band frequency (8.2-12.4 GHz by using substrate integrated waveguide (SIW technique. SIW appears few years backwhich provides an excellent platform in order to design millimeter-wave circuits such as filter, antenna,resonator, coupler and power divider. It offers great compensation for smaller size and can be easily integrated with other planar circuits. The fabrication process can simply be done by using standard Printed Circuit Board (PCB process where the cost of the manufacturing process will be reduced compared to the conventional waveguide. The directional coupler basically implemented at radar, satellite and point-to-point radio. The simulations for this SIW directional coupler design shows good performances with low insertion loss, low return loss, broad operational bandwidth and have high isolation.

  11. Fabrication of the high power input coupler for BEPCⅡ superconducting cavities

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The BEPCII storage ring adopts two 500 MHz superconducting cavities (SCC). Each one is equipped with a 500 MHz input power coupler. The coupler is to feed 150 kW power in continuous wave (CW) mode with both standing and traveling wave modes. Due to high power feeding and high frequency of the coupler, its fabrication is a big challenge. The fabrication started with two key components, the window and the antenna. Up to now, two sets including windows and antennas have beam made by IHEP. And a 270 kW RF power in CW has passed through the coupler during the high power test. The fabrication details are presented in this paper.

  12. Experience with the Vibrant Soundbridge RW-Coupler for round window Vibroplasty with tympanosclerosis.

    Science.gov (United States)

    Iwasaki, Satoshi; Suzuki, Hiroaki; Moteki, Hideaki; Miyagawa, Maiko; Takumi, Yutaka; Usami, Shin-Ichi

    2012-06-01

    Abstract Usage of the Vibrant Soundbridge (VSB) with round window (RW)-Coupler placement at the RW has been shown to successfully treat mixed hearing loss. Coupling between the VSB's floating mass transducer (FMT) and the RW membrane is difficult in the case of sclerosis in the RW and drilling down the bony lip until the RW membrane can be seen completely can possibly induce a perilymphatic fistula. A 68-year-old woman who had bilateral mixed hearing loss with sclerosis in the RW due to tympanosclerosis underwent a RW-Vibroplasty with a RW-Coupler. Speech discrimination scores in quiet and noise and functional gain with the VSB with RW-Coupler were better than those using a conventional hearing aid. The results of the present case have shown the feasibility of implanting a VSB with RW-Coupler in patients with mixed hearing loss due to tympanosclerosis.

  13. Relationship between coupler curve properties of a 4-bar linkage and its dimensional types

    Institute of Scientific and Technical Information of China (English)

    CHU; Jinkui; WANG; Liding; WU; Chen

    2004-01-01

    Three types of 4-bar linkages can trace the same coupler curve according to the cognate mechanism law. Based on the investigation of the relationship between dimensions of a linkage and the harmonic component characteristic parameters of the coupler curve of the linkage, it was found that six types of linkages are related to the same coupler curve, and they belong to two groups of cognate mechanisms, in which the coupler curves have the same shape and are symmetric. The relationships among the dimensional types of these six mechanisms are presented. The corresponding examples have also proved these conclusions. This work enriches the cognate mechanism law, and can result in more candidate mechanisms for mechanism dimensional synthesis.

  14. Ultrafast laser inscription of mid-IR directional couplers for stellar interferometry

    CERN Document Server

    Arriola, Alexander; Choudhury, Debaditya; Labadie, Lucas; Thomson, Robert R

    2014-01-01

    We report the ultrafast laser fabrication and mid-IR characterization (3.39 microns) of four-port evanescent field directional couplers. The couplers were fabricated in a commercial gallium lanthanum sulphide glass substrate using sub-picosecond laser pulses of 1030 nm light. Straight waveguides inscribed using optimal fabrication parameters were found to exhibit propagation losses of 0.8 dB/cm. A series of couplers were inscribed with different interaction lengths, and we demonstrate power splitting ratios of between 8% and 99% for mid-IR light with a wavelength of 3.39 microns. These results clearly demonstrate that ultrafast laser inscription can be used to fabricate high quality evanescent field couplers for future applications in astronomical interferometry.

  15. Ultrafast laser inscription of mid-IR directional couplers for stellar interferometry.

    Science.gov (United States)

    Arriola, Alexander; Mukherjee, Sebabrata; Choudhury, Debaditya; Labadie, Lucas; Thomson, Robert R

    2014-08-15

    We report the ultrafast laser fabrication and mid-IR characterization (3.39 μm) of four-port evanescent field directional couplers. The couplers were fabricated in a commercial gallium lanthanum sulfide glass substrate using sub-picosecond laser pulses of 1030 nm light. Straight waveguides inscribed using optimal fabrication parameters were found to exhibit propagation losses of ∼0.8 dB·cm(-1). A series of couplers were inscribed with different interaction lengths, and we demonstrate power-splitting ratios of between 8% and 99% for mid-IR light with a wavelength of 3.39 μm. These results clearly demonstrate that ultrafast laser inscription can be used to fabricate high-quality evanescent field couplers for future applications in astronomical interferometry.

  16. Two-mode optical state truncation and generation of maximally entangled states in pumped nonlinear couplers

    CERN Document Server

    Miranowicz, A; Miranowicz, Adam; Leonski, Wieslaw

    2006-01-01

    Schemes for optical-state truncation of two cavity modes are analysed. The systems, referred to as the nonlinear quantum scissors devices, comprise two coupled nonlinear oscillators (Kerr nonlinear coupler) with one or two of them pumped by external classical fields. It is shown that the quantum evolution of the pumped couplers can be closed in a two-qubit Hilbert space spanned by vacuum and single-photon states only. Thus, the pumped couplers can behave as a two-qubit system. Analysis of time evolution of the quantum entanglement shows that Bell states can be generated. A possible implementation of the couplers is suggested in a pumped double-ring cavity with resonantly enhanced Kerr nonlinearities in an electromagnetically-induced transparency scheme. The fragility of the generated states and their entanglement due to the standard dissipation and phase damping are discussed by numerically solving two types of master equations.

  17. Simulation and experimental research on polymer fiber mode selection polished coupler

    Institute of Scientific and Technical Information of China (English)

    Fan Ji; Lixin Xu; Feng Li; Chun Gu; Kun Gao; Hai Ming

    2008-01-01

    Multimode dispersion is the main obstacle for high bandwidth in multimode optical fiber (MMF) communication system. Mode selection is an effective method to oppress multimode dispersion. We propose and investigate a kind of polymer optical fiber polished coupler. Beam propagation method (BPM) is employed to calculate the coupling coefficient of transmission modes in MMF coupler, and an output pattern from coupling branch is obtained. Analysis and experiment show that this coupler can select certain modes by changing polished depth, contact area, and intersection angle of two branches, which means that the device can be employed both as a mode selector and a sensor. In addition, simulation shows that five times bandwidth enhancement may be realized by selecting modes with the polymer fiber polished coupler.

  18. Add-Drop Demultiplexer Operating in an Optical Michelson Interferometer Based in Fiber Bragg Gratings for Time Division Multiple Access Systems

    Science.gov (United States)

    Filho, A. F. G. F.; De Sousa, J. R. R.; Guimarães, G. F.; Rocha, H. H. B.; Ferreira, A. C.; Lima, F. T.; Sombra, A. S. B.

    2010-07-01

    This article presents a numerical investigation of the propagation and switching of ultra-short pulses (∼2 ps) using a fiber-optic Michelson interferometer. In this study, the performance of the Michelson interferometer is studied as a function of the non-linear characteristics of the coupler and the fiber Bragg gratings. The numerical studies were done starting from the coupled-mode equations solved using the fourth-order Runge-Kutta method. The switching characteristic of the short pulses was examined as a function of pump power and the dephasing in the reflection amplitude of one of the Bragg gratings in order to obtain an add-drop filter operation. Transmission characteristics, such as cross-talk level, extinction ratio coefficient, and compression factor, were analyzed for different dephasing values and pump powers. Pump powers were examined from below the critical power of the coupler of switching (P = 1 W), at the critical power of switching (Pc = 1.73 W), and above (P = 1.95 W). Through this study, one can verify that the transmission, cross-talk level, extinction coefficient, and compression factor depend on the pump power inserted into the device and in the dephasing. The optical fiber Michelson interferometers with identical gratings in the two output arms implement important components as a demultiplexer in add-drop devices. This device has attracted great interest in the field of all-optical switching in telecommunications for operating with high transmission rates.

  19. Characterization of mode group transfer matrix in multimode couplers using spatial light modulation

    Science.gov (United States)

    Stepniak, G.; Bunge, C. A.

    2016-09-01

    In this paper, spatial light modulation is applied to investigate the selective mode properties of multimode fibers (MMF) and MMF couplers. Spatial light modulator is applied only on the MMF input to excite a selected linearly polarized eigenmode of the MMF. At the system output the impulse and frequency response is studied. By an additional time separation of mode groups achieved during propagation in the MMF, a mode group to mode group transfer matrix of the MMF coupler can be obtained.

  20. Extending The Calibration In The Underwater Sound Reference Division (USRD) Reciprocity Coupler To Incorporate Phase

    Science.gov (United States)

    2016-09-01

    data acquisition equipment and phase measurement added. Some errors due to simplifications in the acoustics of the coupler are left to future work...new data acquisition equipment and phase measurement added. Some errors due to simplifications in the acoustics of the coupler are left to future...using the sample clock for sample rate and the convert clock to time the sequential scans over the active channels within each sample. The driver software

  1. Electromagnetic Design of New RF Power Couplers for the S-DALINAC

    CERN Document Server

    Kunze, Marco; Brunken, M; Gräf, H D; Richter, Achim

    2004-01-01

    New rf power couplers for the Superconducting Darmstadt Linear Accelerator (S-DALINAC) injector have to be designed to transfer rf power of up to 2 kW to the electron beam. This allows injector operation at beam currents from 0.15 mA to 0.2 mA and electron energies up to 14 MeV. The new couplers should possibly provide a external Q of 5·106

  2. A Novel Multimode Waveguide Coupler for Accurate Power Measurement of Traveling Wave Tube Harmonic Frequencies

    Science.gov (United States)

    Wintucky, Edwin G.; Simons, Rainee N.

    2014-01-01

    This paper presents the design, fabrication and test results for a novel waveguide multimode directional coupler (MDC). The coupler fabricated from two dissimilar waveguides is capable of isolating the power at the second harmonic frequency from the fundamental power at the output port of a traveling-wave tube (TWT). In addition to accurate power measurements at harmonic frequencies, a potential application of the MDC is in the design of a beacon source for atmospheric propagation studies at millimeter-wave frequencies.

  3. Design and Optimization of Air-Doped 3-dB Terahertz Fiber Directional Couplers

    DEFF Research Database (Denmark)

    Bao, Hualong; Nielsen, Kristian; Rasmussen, Henrik K.;

    2014-01-01

    We present a thorough practical design optimization of broadband low loss, terahertz (THz) photonic crystal fiber directional couplers in which the two cores are mechanically down- doped with a triangular array of air holes.......We present a thorough practical design optimization of broadband low loss, terahertz (THz) photonic crystal fiber directional couplers in which the two cores are mechanically down- doped with a triangular array of air holes....

  4. Power Analysis and Experimental Study of the Fiber Null Coupler with an Acousto-optic Device

    Institute of Scientific and Technical Information of China (English)

    WU Lei; ZHENG Yuan; QI Jiang; PU Hongtu; CHEN Shuqiang

    2002-01-01

    A single-mode fiber acousto-optic (AO) switch based on a null coupler at wavelength of 1.55 μm is reported.According to the coupled mode theory,power distribution of the null coupler with the acoustic-wave is formulated for general case.Excess loss of 0.1 dB and the schematic graph of throughput and coupled power are obtained experimentally.

  5. Localized Mode Enhanced Coupler Based on Quasi-One-Dimensional Photonic Crystal Microstrip

    Institute of Scientific and Technical Information of China (English)

    LI Yun-Hui; JIANG Hai-Tao; HE Li; LI Hong-Qiang; ZHANG Ye-Wen; CHEN Hong

    2004-01-01

    We propose a novel localized mode enhanced (LME) coupler based on quasi-one-dimensional photonic crystal microstrips, which is promising to be applied in wavelength division multiplexed microwave communication systems. Compared to the traditional microstrip coupler, the LME structure has two advantages: high efficiency and frequency selectivity. Even in a relatively far coupling distance, this structure can still achieve a high efficiency about 50%. The frequency selectivity can be realized by simply tuning the distance between two transmission lines.

  6. Asymmetric hollow POF coupler design for portable optical access card system

    Science.gov (United States)

    Ehsan, Abang Annuar; Shaari, Sahbudin; Abd Rahman, Mohd Kamil

    2009-05-01

    An optical code generating device using plastic optical fiber (POF) coupler for portable optical access card system is presented. The code generating device constructed using asymmetric hollow POF coupler design provides a unique series of output light intensities which are successively used as an optical code. Each coupler will be assigned with a unique optical code based on the asymmetrical waveguide design. Non-sequential ray tracing simulation of various coupler designs showed a linear relationship between the tap-off ratio (TOFR) and the waveguide tap width. The results for the simulated and fabricated 1x2 asymmetric couplers show the same linear characteristics between the TOFR and the tap width. The simulated devices show a TOFR variation from 18.6% to 49.9% whereas the TOFR for the fabricated metal-based devices varies from 10.7% up to 47.7%, for a tap width of 500 μm to 1 mm. The insertion loss for the 1x2 asymmetric coupler at the tap line varies from 12.7 dB to 21.2 dB whereas for the bus line, the average insertion loss is about 12 dB.

  7. Compact and Wideband Parallel-Strip 180° Hybrid Coupler with Arbitrary Power Division Ratios

    Directory of Open Access Journals (Sweden)

    Leung Chiu

    2013-01-01

    Full Text Available This paper presents a class of wideband 180° hybrid (rat race couplers implemented by parallel-strip line. By replacing the 270° arm of a conventional 180° hybrid coupler by a 90° arm with phase inverter, the bandwidth of the coupler is greatly enhanced and the total circuit size is reduced by almost half. Simple design formulas relating the characteristic impedance of the arms and power division ration are derived. To demonstrate the concept, four couplers with different power division ratios of 1, 2, 4, and 8 were designed, fabricated, and tested. S-parameters of the coupler are simulated and measured with good agreement. All working prototypes operate more than 112% impedance bandwidth with more than 25 dB port-to-port isolation and less than 5° absolute phase imbalance. The proposed 180° hybrid couplers can be employed as a wideband in-phase/differential power divider/combiner, which are essential for many RF and microwave subsystem designs.

  8. Exploiting a Transmission Grating Spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Ronald E. Bell

    2004-12-08

    The availability of compact transmission grating spectrometers now allows an attractive and economical alternative to the more familiar Czerny-Turner configuration for many high-temperature plasma applications. Higher throughput is obtained with short focal length refractive optics and stigmatic imaging. Many more spectra can be obtained with a single spectrometer since smaller, more densely packed optical input fibers can be used. Multiple input slits, along with a bandpass filter, can be used to maximize the number of spectra per detector, providing further economy. Curved slits can correct for the strong image curvature of the short focal length optics. Presented here are the governing grating equations for both standard and high-dispersion transmission gratings, defining dispersion, image curvature, and desired slit curvature, that can be used in the design of improved plasma diagnostics.

  9. High Efficiency Low Scatter Echelle Grating Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A high efficiency low scatter echelle grating will be developed using a novel technique of multiple diamond shaving cuts. The grating will have mirror surfaces on...

  10. Polymer optical fiber bragg grating sensors

    DEFF Research Database (Denmark)

    Stefani, Alessio; Yuan, Scott Wu; Andresen, Søren

    2010-01-01

    Fiber-optical accelerometers based on polymer optical fiber Bragg gratings are reported. We have written fiber Bragg gratings for 1550 nm and 850 nm operations, characterized their temperature and strain response, and tested their performance in a prototype accelerometer....

  11. Subwavelength grating as both emission mirror and electrical contact for VCSELs in any material system

    Science.gov (United States)

    Czyszanowski, Tomasz; Gebski, Marcin; Dems, Maciej; Wasiak, Michał; Sarzała, Robert; Panajotov, Krassimir

    2017-01-01

    Semiconductor-metal subwavelength grating (SMSG) can serve a dual purpose in vertical-cavity surface-emitting lasers (VCSELs), as both optical coupler and current injector. SMSGs provide optical as well as lateral current confinement, eliminating the need for ring contacts and lateral build-in optical and current confinement, allowing their implementation on arbitrarily large surfaces. Using an SMSG as the top mirror enables fabrication of monolithic VCSELs from any type of semiconductor crystal. The construction of VCSELs with SMSGs requires significantly less p-type material, in comparison to conventional VCSELs. In this paper, using a three-dimensional, fully vectorial optical model, we analyse the properties of the stand-alone SMSG in a number of semiconductor materials for a broad range of wavelengths. Integrating the optical model with thermal and electrical numerical models, we then simulate the threshold operation of an exemplary SMSG VCSEL. PMID:28079149

  12. Distributed OTDR-interferometric sensing network with identical ultra-weak fiber Bragg gratings.

    Science.gov (United States)

    Wang, Chen; Shang, Ying; Liu, Xiao-Hui; Wang, Chang; Yu, Hai-Hu; Jiang, De-Sheng; Peng, Gang-Ding

    2015-11-02

    We demonstrate a distributed sensing network with 500 identical ultra-weak fiber Bragg gratings (uwFBGs) in an equal separation of 2m using balanced Michelson interferometer of the phase sensitive optical time domain reflectometry (φ-OTDR) for acoustic measurement. Phase, amplitude, frequency response and location information can be directly obtained at the same time by using the passive 3 × 3 coupler demodulation. Lab experiments on detecting sound waves in water tank are carried out. The results show that this system can well demodulate distributed acoustic signal with the pressure detection limit of 0.122Pa and achieve an acoustic phase sensitivity of around -158dB (re rad/μPa) with a relatively flat frequency response between 450Hz to 600Hz.

  13. Developing arrayed waveguide grating spectrographs for multi-object astronomical spectroscopy.

    Science.gov (United States)

    Cvetojevic, Nick; Jovanovic, Nemanja; Lawrence, Jon; Withford, Michael; Bland-Hawthorn, Joss

    2012-01-30

    With the aim of utilizing arrayed waveguide gratings for multi-object spectroscopy in the field of astronomy, we outline several ways in which standard telecommunications grade chips should be modified. In particular, by removing the parabolic-horn taper or multimode interference coupler, and injecting with an optical fiber directly, the resolving power was increased threefold from 2400 ± 200 (spectral resolution of 0.63 ± 0.2 nm) to 7000 ± 700 (0.22 ± 0.02 nm) while attaining a throughput of 77 ± 5%. More importantly, the removal of the taper enabled simultaneous off-axis injection from multiple fibers, significantly increasing the number of spectra that can be obtained at once (i.e. the observing efficiency). Here we report that ~12 fibers can be injected simultaneously within the free spectral range of our device, with a 20% reduction in resolving power for fibers placed at 0.8 mm off-centre.

  14. Vortex and LG01-mode Nd:YAG laser involving a circular Dammann grating

    Science.gov (United States)

    Xu, Yun; Han, Xiahui; Li, Guiyun; Liu, Jinyu; Xia, Kegui; Li, Jianlang

    2016-05-01

    By introducing a circular Dammann grating (CDG) into the pump unit, we demonstrated an end-pumped Nd:YAG laser that emitted a vortex and first-order LG mode with high laser efficiency and high power. In our scheme, the CDG was used to reshape the pumping light into an annular profile, and the adaptation of it was realized easily by inserting it into the pump unit of a conventional end-pumped solid-state laser; the laser cavity was simple, compact, and consisted of only a laser crystal and an output coupler. The beam power of this laser reached 1.86 W at an absorbed pump power of 6.38 W with a slope efficiency of 34.5%.

  15. Subwavelength grating as both emission mirror and electrical contact for VCSELs in any material system

    Science.gov (United States)

    Czyszanowski, Tomasz; Gebski, Marcin; Dems, Maciej; Wasiak, Michał; Sarzała, Robert; Panajotov, Krassimir

    2017-01-01

    Semiconductor-metal subwavelength grating (SMSG) can serve a dual purpose in vertical-cavity surface-emitting lasers (VCSELs), as both optical coupler and current injector. SMSGs provide optical as well as lateral current confinement, eliminating the need for ring contacts and lateral build-in optical and current confinement, allowing their implementation on arbitrarily large surfaces. Using an SMSG as the top mirror enables fabrication of monolithic VCSELs from any type of semiconductor crystal. The construction of VCSELs with SMSGs requires significantly less p-type material, in comparison to conventional VCSELs. In this paper, using a three-dimensional, fully vectorial optical model, we analyse the properties of the stand-alone SMSG in a number of semiconductor materials for a broad range of wavelengths. Integrating the optical model with thermal and electrical numerical models, we then simulate the threshold operation of an exemplary SMSG VCSEL.

  16. A Composite Grating for Moire Interferometry.

    Science.gov (United States)

    1987-07-01

    shown in Figure 7 in which two virtual reference gratings of frequencies 2400 and 600 lines/mm were used. This arrangement corresponds to a fringe...fields at the two virtual reference grating frequencies of 2400/600 lines/mm. The light paths of the two virtual reference gratings are controlled by...frequencies were selectively recorded. Figure 10 and 11 shows two moire fringe patterns for virtual reference grating frequencies of 2400 lines/mm and 600

  17. Fabrication of Polymer Optical Fibre (POF Gratings

    Directory of Open Access Journals (Sweden)

    Yanhua Luo

    2017-03-01

    Full Text Available Gratings inscribed in polymer optical fibre (POF have attracted remarkable interest for many potential applications due to their distinctive properties. This paper overviews the current state of fabrication of POF gratings since their first demonstration in 1999. In particular we summarize and discuss POF materials, POF photosensitivity, techniques and issues of fabricating POF gratings, as well as various types of POF gratings.

  18. Grating-Coupled Waveguide Cloaking

    Institute of Scientific and Technical Information of China (English)

    WANG Jia-Fu; QU Shao-Bo; XU Zhuo; MA Hua; WANG Cong-Min; XIA Song; WANG Xin-Hua; ZHOU Hang

    2012-01-01

    Based on the concept of a grating-coupled waveguide (GCW),a new strategy for realizing EM cloaking is presented.Using metallic grating,incident waves are firstly coupled into the effective waveguide and then decoupled into free space behind,enabling EM waves to pass around the obstacle.Phase compensation in the waveguide keeps the wave-front shape behind the obstacle unchanged.Circular,rectangular and triangular cloaks are presented to verify the robustness of the GCW cloaking.Electric field animations and radar cross section (RCS)comparisons convincingly demonstrate the cloaking effect.

  19. Hybrid grating reflectors: Origin of ultrabroad stopband

    DEFF Research Database (Denmark)

    Park, Gyeong Cheol; Taghizadeh, Alireza; Chung, Il-Sug

    2016-01-01

    Hybrid grating (HG) reflectors with a high-refractive-index cap layer added onto a high contrast grating (HCG) provide a high reflectance close to 100% over a broader wavelength range than HCGs. The combination of a cap layer and a grating layer brings a strong Fabry-Perot (FP) resonance as well...

  20. Performance optimization of RoF systems using 120° hybrid coupler for OSSB signal against third order intermodulation

    Science.gov (United States)

    Kumar, Parvin; Sharma, Sanjay Kumar; Singla, Shelly

    2016-10-01

    The performance of radio over fiber (RoF) system with dual drive Mach Zehender modulator has been optimized against third order intermodulation distortion by using 120° hybrid coupler in transmission system. Signal to Noise Distortion ratio (SNDR) has been evaluated and a performance comparison is also drawn for the systems based on 90° and 120° hybrid coupler in both noise and intermodulation distortion dominant environment. The SNDR is efficiently improved by employing 120° hybrid coupler in noise dominant and intermodulation distortion dominant environment. An improvement of 4.86 dB is obtained in the maximum SNDR with 120° hybrid coupler is obtained over at 20 km optical fiber length compared with a 90° hybrid coupler based system. A significant reduction of third order intermodulation power at receiver has also been observed with 120° hybrid coupler.

  1. Compact rat-race ring coupler with meander high-impedance transmission line and port impedance matching

    Directory of Open Access Journals (Sweden)

    Jun He

    2015-08-01

    Full Text Available A novel compact rat-race ring coupler with meander high-impedance transmission line and port impedance matching is presented in this Letter. First, a ring coupler with high port impedance is designed using meander lines. Secondly, an impedance matching section is designed to match the high port impedance to ordinary 50 Ω. The proposed coupler effectively reduces occupied area to 16.8% of conventional one. The design is validated both by simulation and measurement.

  2. "Hot-wire" microfluidic flowmeter based on a microfiber coupler.

    Science.gov (United States)

    Yan, Shao-Cheng; Liu, Zeng-Yong; Li, Cheng; Ge, Shi-Jun; Xu, Fei; Lu, Yan-Qing

    2016-12-15

    Using an optical microfiber coupler (MC), we present a microfluidic platform for strong direct or indirect light-liquid interaction by wrapping a MC around a functionalized capillary. The light propagating in the MC and the liquid flowing in the capillary can be combined and divorced smoothly, keeping a long-distance interaction without the conflict of input and output coupling. Using this approach, we experimentally demonstrate a "hot-wire" microfluidic flowmeter based on a gold-integrated helical MC device. The microfluid inside the glass channel takes away the heat, then cools the MC and shifts the resonant wavelength. Due to the long-distance interaction and high temperature sensitivity, the proposed microfluidic flowmeter shows an ultrahigh flow rate sensitivity of 2.183 nm/(μl/s) at a flow rate of 1 μl/s. The minimum detectable change of the flow rate is around 9 nl/s at 1 μl/s.

  3. Higher Order Mode Coupler Heating in Continuous Wave Operation

    Science.gov (United States)

    Solyak, N.; Awida, M.; Hocker, A.; Khabibobulline, T.; Lunin, A.

    Electromagnetic heating due to higher order modes (HOM) propagation is particularly a concern for continuous wave (CW) particle accelerator machines. Power on the order of several watts could flow out of the cavity's HOM ports in CW operations. The upgrade of the Linac Coherent Light Source (LCLS-II) at SLAC requires a major modification of the design of the higher order mode (HOM) antenna and feed through of the conventional ILC elliptical 9-cell cavity in order to utilize it for LCLS-II. The HOM antenna is required to bear higher RF losses, while relatively maintaining the coupling level of the higher order modes. In this paper, we present a detailed analysis of the heating expected in the HOM coupler with a thorough thermal quench study in comparison with the conventional ILC design. We discuss also how the heat will be removed from the cavity through RF cables with specially designed cooling straps. Finally, we report on the latest experimental results of cavity testing in vertical and horizontal cryostats.

  4. Wavelength tunable long period gratings based on silica waveguide geometric modulation

    Science.gov (United States)

    Jiang, Jia; Callender, Claire L.; Ledderhof, Christopher J.; Ding, Jianfu

    2011-03-01

    This paper presents planar long period grating (LPG) devices based on a periodic thickness variation in the waveguide core, fabricated by etching into the lower cladding layer prior to definition of the waveguide layer. This periodic geometric change results in a stable grating structure and a permanent refractive index modulation of 10-4 or higher, which is comparable to the index modulation in Ge-doped silica material induced by photo irradiation techniques widely used in fiber grating fabrication. This grating produces a strong resonance at a particular wavelength in the transmission spectrum, enabling a range of applications from wavelength filtering to signal distribution in communication networks. In this work, a polymer and silica hybrid architecture has been implemented in order to achieve wavelength tunability. Using a thermally oxidized silicon layer as a lower cladding, a Ge-doped silica ridge is patterned using conventional photolithography and reactive ion etching to form the waveguide core, which is then covered with a low index fluorinated polymer cladding. While the silica waveguides offer a lower propagation loss and an easy processability, the top polymer allows the device to be thermally tuned over a wide wavelength range by exploiting the opposite thermo-optic coefficient between fluorinated polymer and silica, and the high sensitivity of the underlying LPG to the refractive index of the cladding layer. Strong rejection bands have been demonstrated in the C+L band, in good agreement with theoretical calculations. Corrugated structures have been defined across an extended area under multiple waveguides resulting in coupling of light from the fundamental mode into cladding modes and back into the neighboring waveguides located far from the evanescent coupling distance. This kind of coupler can facilitate devices that require extraction and control of a particular waveguide mode for applications such as multiple channel signal distribution and

  5. Running gratings in photoconductive materials

    DEFF Research Database (Denmark)

    Kukhtarev, N. V.; Kukhtareva, T.; Lyuksyutov, S. F.

    2005-01-01

    gratings at small-contrast approximation and also are applicable for the description of space-charge wave domains. We discuss spatial domain and subharmonic beam formation in bismuth silicon oxide (BSO) crystals in the framework of the small-contrast approximation of STPM. The experimental results...

  6. A tunable dual-broad-band branch-line coupler utilizing composite right/left-handed transmission lines

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yu; HU Li; HE Sai-ling

    2005-01-01

    A tunable dual-broad-band branch-line coupler (BLC) utilizing composite right/left-handed (CRLH) transmission lines is presented. Two λ/4 segments consisting of CRLH transmission lines are added to each port to broaden the dual bands of the branch-line coupler. Numerical simulation and optimal design of the novel coupler are presented. The dual bands of the novel coupler are tunable and broad. The 1-dB bandwidth of each passband is more than 16% of the central frequency.

  7. Calculation of thermal noise in grating reflectors

    CERN Document Server

    Heinert, Daniel; Friedrich, Daniel; Hild, Stefan; Kley, Ernst-Bernhard; Leavey, Sean; Martin, Iain W; Nawrodt, Ronny; Tünnermann, Andreas; Vyatchanin, Sergey P; Yamamoto, Kazuhiro

    2013-01-01

    Grating reflectors have been repeatedly discussed to improve the noise performance of metrological applications due to the reduction or absence of any coating material. So far, however, no quantitative estimate on the thermal noise of these reflective structures exists. In this work we present a theoretical calculation of a grating reflector's noise. We further apply it to a proposed 3rd generation gravitational wave detector. Depending on the grating geometry, the grating material and the temperature we obtain a thermal noise decrease by up to a factor of ten compared to conventional dielectric mirrors. Thus the use of grating reflectors can substantially improve the noise performance in metrological applications.

  8. Curved VPH gratings for novel spectrographs

    Science.gov (United States)

    Clemens, J. Christopher; O'Donoghue, Darragh; Dunlap, Bart H.

    2014-07-01

    The introduction of volume phase holographic (VPH) gratings into astronomy over a decade ago opened new possibilities for instrument designers. In this paper we describe an extension of VPH grating technology that will have applications in astronomy and beyond: curved VPH gratings. These devices can disperse light while simultaneously correcting aberrations. We have designed and manufactured two different kinds of convex VPH grating prototypes for use in off-axis reflecting spectrographs. One type functions in transmission and the other in reflection, enabling Offnerstyle spectrographs with the high-efficiency and low-cost advantages of VPH gratings. We will discuss the design process and the tools required for modelling these gratings along with the recording layout and process steps required to fabricate them. We will present performance data for the first convex VPH grating produced for an astronomical spectrograph.

  9. Grating light modulator for projection display

    Institute of Scientific and Technical Information of China (English)

    Jiyong Sun; Shanglian Huang; Jie Zhang; Zhihai Zhang; Yong Zhu

    2009-01-01

    A novel grating light modulator for projection display is introduced. It consists of an upper moveable grat-ing, a bottom mirror, and four supporting posts between them. The moveable grating and the bottom mir-ror compose a phase grating whose phase difference is controlled by the actuating voltage. When the phase difference is 2kπ, the grating light modulator will switch the incident light to zero-order diffraction; when the phase difference is (2k - 1)π, the grating light modulator will diffract light to first-order diffraction. A 16 × 16 modulator array is fabricated by the surface micromachining technology. The device works well when it is actuated by a voltage with 1-kHz frequency and 10-V amplitude. The fabricated grating light modulator can show blackness and brightness when controlled by the voltage. This modulator has potential applications in projection display system.

  10. Heat-driven thermoacoustic cryocooler operating at liquid hydrogen temperature with a unique coupler

    Science.gov (United States)

    Hu, J. Y.; Luo, E. C.; Li, S. F.; Yu, B.; Dai, W.

    2008-05-01

    A heat-driven thermoacoustic cryocooler is constructed. A unique coupler composed of a tube, reservoir, and elastic diaphragm is introduced to couple a traveling-wave thermoacoustic engine (TE) and two-stage pulse tube refrigerator (PTR). The amplitude of the pressure wave generated in the engine is first amplified in the coupler and the wave then passes into the refrigerator to pump heat. The TE uses nitrogen as its working gas and the PTR still uses helium as its working gas. With this coupler, the efficiency of the system is doubled. The engine and coupler match at a much lower operating frequency, which is of great benefit for the PTR to obtain a lower cooling temperature. The coupling place between the coupler and engine is also optimized. The onset problem is effectively solved. With these improvements, the heat-driven thermoacoustic cryocooler reaches a lowest temperature of 18.1K, which is the demonstration of heat-driven thermoacoustic refrigeration technology used for cooling at liquid hydrogen temperatures.

  11. RF Coupler Design for the TRIUMF ISAC-II Superconducting Quarter Wave Resonator

    CERN Document Server

    Poirier, R L; Harmer, P; Laxdal, R E; Mitra, A K; Sekatchev, I; Waraich, B; Zvyagintsev, V

    2004-01-01

    An RF Coupler for the ISAC-II medium beta (β=0.058 and 0.071) superconducting quarter wave resonators was designed and tested at TRIUMF. The main goal of this development was to achieve stable operation of superconducting cavities at high acceleration gradients and low thermal load to the helium refrigeration system. The cavities will operate at 6 MV/m acceleration gradient in overcoupled mode at a forward power 200 W at 106 MHz. The overcoupling provides ±20 Hz cavity bandwidth, which improves the stability of the RF control system for fast helium pressure fluctuations, microphonics and environmental noise. Choice of materials, cooling with liquid nitrogen, aluminum nitride RF window and thermal shields insure a small thermal load on the helium refrigeration system by the Coupler. An RF finger contact which causedμdust in the coupler housing was eliminated without any degradation of the coupler performance. RF and thermal calculations, design and test results on the coupler are p...

  12. Magnetic field sensor based on cascaded microfiber coupler with magnetic fluid

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Lianmin; Su, Delong; Wang, Zhaofang [College of Science, University of Shanghai for Science and Technology, Shanghai 200093 (China); Pu, Shengli, E-mail: shlpu@usst.edu.cn [College of Science, University of Shanghai for Science and Technology, Shanghai 200093 (China); Shanghai Key Laboratory of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093 (China); Zeng, Xianglong [The Key Lab of Specialty Fiber Optics and Optical Access Network, Shanghai University, Shanghai 200072 (China); Lahoubi, Mahieddine [Laboratory L.P.S., Department of Physics, Faculty of Sciences, Badji-Mokhtar Annaba University, Annaba 23000 (Algeria)

    2016-09-07

    A kind of magnetic field sensor based on cascaded microfiber coupler with magnetic fluid is proposed and experimentally demonstrated. The magnetic fluid is utilized as the cladding of the fused regions of the cascaded microfiber coupler. As the interference valley wavelength of the sensing structure is sensitive to the ambient variation, considering the magnetic-field-dependent refractive index of magnetic fluid, the proposed structure is employed for magnetic field sensing. The effective coupling length for each coupling region of the as-fabricated cascaded microfiber coupler is 6031 μm. The achieved sensitivity is 125 pm/Oe, which is about three times larger than that of the previously similar structure based on the single microfiber coupler. Experimental results indicate that the sensing sensitivity can be easily improved by increasing the effective coupling length or cascading more microfiber couplers. The proposed magnetic field sensor is attractive due to its low cost, immunity to electromagnetic interference, as well as high sensitivity, which also has the potentials in other tunable all-fiber photonic devices, such as filter.

  13. Characteristics Of Fused Couplers Below Cut-Off

    Science.gov (United States)

    Meyer, T. J.; Tekippe, V. J.

    1989-02-01

    A number of different architectures are being explored for the utilization of optical fiber in the subscriber loop. In addition to reliability and maintainability, cost is a prime consideration since full implementation of fiber in the local loop will not occur until it is economically viable. It is becoming increasingly clear that in order to accommodate a number of ISDN applications, including high definition television (HDTV), singlemode fiber with a singlemode laser at the terminal end will be required. The situation at the subscriber end is quite different, however. The data rates are expected to be low on the return path to allow for POTS ( plain old telephone service) and some data transfer. When this requirement is combined with cost and reliability considerations, the inexpensive lasers developed for the CD (compact disk) market become quite attractive. The biggest disadvantage of this source is that the fiber which is optimized for singlemode operation at 1300nm tends to be multimode in the 800nm band where these lasers operate. Previous papers have considered such effects as modal noise and pulse dispersion when using these lasers with fiber that is singlemode in the 1300nm band.[1] Another consideration is the passive components required to implement such an architecture. Figure 1 shows a typical bidirectional design with full duplex operation on a single fiber. The key component is the 800/1300 wavelength division multiplexer/demultiplexer (WDM). Because of the multimode nature of the fiber in the 800nm band, all fiber approaches to fabricating the WDM, such as the fused beconical taper (FBT) approach, raise new issues which are not encountered, for example, with 1300/1500nm WDM's.[2] In this paper we discuss the effects of the multimode behavior of the fiber on the performance of fused couplers and WDM's.

  14. Effective grating theory for resonance domain surface-relief diffraction gratings.

    Science.gov (United States)

    Golub, Michael A; Friesem, Asher A

    2005-06-01

    An effective grating model, which generalizes effective-medium theory to the case of resonance domain surface-relief gratings, is presented. In addition to the zero order, it takes into account the first diffraction order, which obeys the Bragg condition. Modeling the surface-relief grating as an effective grating with two diffraction orders provides closed-form analytical relationships between efficiency and grating parameters. The aspect ratio, the grating period, and the required incidence angle that would lead to high diffraction efficiencies are predicted for TE and TM polarization and verified by rigorous numerical calculations.

  15. Cross-fiber Bragg grating transducer

    Science.gov (United States)

    Albin, Sacharia (Inventor); Zheng, Jianli (Inventor); Lavarias, Arnel (Inventor)

    2000-01-01

    A transducer has been invented that uses specially-oriented gratings in waveguide a manner that allows the simultaneous measurement of physical phenomena (such as shear force, strain and temperature) in a single sensing element. The invention has a highly sensitive, linear response and also has directional sensitivity with regard to strain. The transducer has a waveguide with a longitudinal axis as well as two Bragg gratings. The transducer has a first Bragg grating associated with the waveguide that has an angular orientation .theta..sub.a relative to a perpendicular to the longitudinal axis such that 0.degree.<.theta..sub.a <.theta..sub.max. The second Bragg grating is associated with the waveguide in such a way that the angular orientation .theta..sub.b of the grating relative to a perpendicular to the longitudinal axis is (360.degree.-.theta..sub.max)<.theta..sub.b <360.degree.. The first Bragg grating can have a periodicity .LAMBDA..sub.a and the second Bragg grating can have a periodicity .LAMBDA..sub.b such that the periodicity .LAMBDA..sub.a of the first Bragg grating does not equal the periodicity .LAMBDA..sub.b of the second Bragg grating. The angle of the gratings can be such that .theta..sub.a =360.degree.-.theta..sub.b. The waveguide can assume a variety of configurations, including an optical fiber, a rectangular waveguide and a planar waveguide. The waveguide can be fabricated of a variety of materials, including silica and polymer material.

  16. High-performance cryogenic fractal 180° hybrid power divider with integrated directional coupler

    Science.gov (United States)

    Ladu, Adelaide; Montisci, Giorgio; Valente, Giuseppe; Navarrini, Alessandro; Marongiu, Pasqualino; Pisanu, Tonino; Mazzarella, Giuseppe

    2017-06-01

    A 180° hybrid and a directional coupler to be employed in the P-band cryogenic receiver of the Sardinia Radio Telescope are proposed in this work. An in-depth study of the issues related to the use of microwave components for cryogenic radio astronomy receivers is carried out to select the best suited technology and configuration. As a result, a planar fractal 180° hybrid configuration available in the literature has been optimized aiming to increase the operating bandwidth in order to comply with the design specifications of the application at hand. A coupled line directional coupler with weak coupling and high isolation, used to calibrate the receiver chain, is cascaded to the 180° hybrid and realized in the same layout. The final device, consisting of the 180° hybrid and the directional coupler, has been manufactured and tested at the cryogenic temperature of 20 K, showing a good agreement between experimental results and predicted performance.

  17. Relationship between rheological manufacturing process and optical performance of optical fiber coupler

    Institute of Scientific and Technical Information of China (English)

    SHUAI Ci-jun; DUAN Ji-an; ZHONG Jue

    2006-01-01

    Through theoretical analysis and experiments, the viscoelastic mechanical model of optical fiber coupler in theprocess of fused biconical taper was established, and the numerical analysis in non-uniform temperature field was made. The results show that the rheological parameters, such as drawing speed and fused temperature, have a tremendous influence on stress distribution and performance of optical fiber coupler, especially the influence of fused temperature. The change of fused temperature by 5 ℃ can lead to the change of the maximum stress by 30% and stress difference by 20% in the same cross section. The change of temperature gradient by 3% can result in the change of stress difference by 90%. In the present condition of rheological technology, rheological defects such as crystallizations and microcracks are easy to generate in the optical fiber coupler.

  18. Ultra broadband waveveguide coupler using an anisotropic sub-wavelength metamaterial

    CERN Document Server

    Halir, Robert; Luque-González, Jose Manuel; Sarmiento-Merenguel, Jose Darío; Schmid, Jens; Wangüemert-Pérez, Gonzalo; Xu, Dan-Xia; Wang, Shurui; Ortega-Moñux, Alejandro; Molina-Fernández, Íñigo

    2016-01-01

    Multimode interference couplers are a fundamental building block in many integrated photonic systems, ranging from high-speed coherent receivers to quantum splitters. However, their basic structure has remained fundamentally unchanged for almost four decades, limiting their size and operation bandwidth. Using sub-wavelength metamaterials, photonic devices with break-through size and performance have been recently reported. Leveraging the inherent anisotropy of these structures, here we derive a semi-analytic expression that enables the design of compact and ultra broadband multimode interference couplers. We experimentally demonstrate virtually perfect operation over a bandwidth in excess of 300nm (500nm in simulation), for a device three times shorter than its conventional counterpart, making this the most broadband multimode interference coupler reported to date. These results will enable ultra broadband integrated systems for applications in communications and sensing.

  19. A case of the vibrant soundbridge stapes coupler in patients with mixed hearing loss.

    Science.gov (United States)

    Park, Ah Young; Jeon, Ju Hyun; Moon, In Seok; Choi, Jae Young

    2014-09-01

    The Vibrant Soundbridge (VSB) with stapes clip coupler placement at the stapes head has been used successfully to treat mixed hearing loss. Coupling between the floating mass transducer of the VSB and the stapes head is technically less demanding than incus vibroplasty and is more likely to generate a positive outcome without significantly changing residual hearing or resulting in medical or surgical complications. A 65-year-old man with bilateral mixed hearing loss and chronic otitis media underwent vibroplasty with a stapes clip coupler. Speech discrimination scores in both quiet and noise environments showed better functional gain with the VSB than with the use of a conventional hearing aid. The results of the present case show the feasibility of implanting a VSB with a stapes coupler in patients with mixed hearing loss due to chronic otitis media.

  20. A Novel Acoustic Emission Fiber Optic Sensor Based on a Single Mode Optical Fiber Coupler

    Institute of Scientific and Technical Information of China (English)

    CHEN Rongsheng; LIAO Yanbiao; ZHENG Gangtie; LIU Tongyu; Gerard Franklyn Fernando

    2001-01-01

    This paper reports, for the first time, on the use of a fused-taper single mode optical fiber coupler as a sensing element for the detection of acoustic emission (AE) and ultrasound. When an acoustic wave impinges on the mode-coupling region of a coupler, the coupling coefficient is modulated via the photo-elastic effect. Therefore, the transfer function of the coupler is modulated by an acoustic wave. The sensitivity of the sensor at 140 kHz was approximately 5.2 mV/Pa and the noise floor was 1 Pa. The bandwidth of the sensor was up to several hundred kHz. This AE sensor exhibits significant advantage compared with interferometer-based AE sensors.

  1. Discussion on coupling mechanism of asymmetric CRLH/RH TL coupler

    Institute of Scientific and Technical Information of China (English)

    WANG You-zhen; ZHANG Ye-wen; HE Li; LIU Fu-qiang; LI Hong-qiang; CHEN Hong

    2006-01-01

    A quasi 0-dB coupler composed of a composite right-/left-handed transmission line (CRLH TL) and a conventional right-handed transmission line (RH TL) is presented. This coupler is shown to exhibit broad bandwidth and tight coupling char acteristics. The circuit model and S-parameter results are also demonstrated. Another coupler with properly chosen loaded lumped-elements LL and CL in the CRLH TL is proposed to gain further understanding of the coupling mechanism. By adjusting the spacing between the CRLH TL and RH TL from 8 mm to 0.2 mm, it can be shown that backward coupling occurs in the left-handed region.

  2. Multi-coupler side-pumped Yb-doped double-clad fiber laser

    Institute of Scientific and Technical Information of China (English)

    Pan Ou(欧攀); Ping Yan(闫平); Mali Gong(巩马理); Wenlou Wei(韦文楼)

    2004-01-01

    The side-coupler of angle polished method, using angle-polished multimode fiber and optical adhesive, is used to efficiently pump an Yb-doped double-clad fiber laser. The maximum coupling efficiency of 78.6% is achieved by the side-coupler for a multimode fiber with a circular core of 200 μm and a double-clad fiber with a 350/400 μm D-shaped inner cladding. While laser diodes (LDs) with three side-couplers are simultaneously used as pump sources, maximum output power of 1.38 W and slope efficiency of 48.9% are demonstrated in the fiber laser system.

  3. Multi-coupler side-pumped Yb-doped double-clad fiber laser

    Institute of Scientific and Technical Information of China (English)

    欧攀; 闫平; 巩马理; 韦文楼

    2004-01-01

    The side-coupler of angle polished method, using angle-polished multimode fiber and optical adhesive, is used to efficiently pump an Yb-doped double-clad fiber laser. The maximum coupling efficiency of 78.6%is achieved by the side-coupler for a multimode fiber with a circular core of 200 μm and a double-clad fiber with a 350/400 μm D-shaped inner cladding. While laser diodes (LDs) with three side-couplers are simultaneously used as pump sources, maximum output power of 1.38 W and slope efficiency of 48.9% are demonstrated in the fiber laser system.

  4. RF characterization and testing of ridge waveguide transitions for RF power couplers

    Science.gov (United States)

    Kumar, Rajesh; Jose, Mentes; Singh, G. N.; Kumar, Girish; Bhagwat, P. V.

    2016-12-01

    RF characterization of rectangular to ridge waveguide transitions for RF power couplers has been carried out by connecting them back to back. Rectangular waveguide to N type adapters are first calibrated by TRL method and then used for RF measurements. Detailed information is obtained about their RF behavior by measurements and full wave simulations. It is shown that the two transitions can be characterized and tuned for required return loss at design frequency of 352.2 MHz. This opens the possibility of testing and conditioning two transitions together on a test bench. Finally, a RF coupler based on these transitions is coupled to an accelerator cavity. The power coupler is successfully tested up to 200 kW, 352.2 MHz with 0.2% duty cycle.

  5. Design of Dual-Band Two-Branch-Line Couplers with Arbitrary Coupling Coefficients in Bands

    Directory of Open Access Journals (Sweden)

    I. Prudyus

    2014-12-01

    Full Text Available A new approach to design dual-band two-branch couplers with arbitrary coupling coefficients at two operating frequency bands is proposed in this article. The method is based on the usage of equivalent subcircuits input reactances of the even-mode and odd-mode excitations. The exact design formulas for three options of the dual-band coupler with different location and number of stubs are received. These formulas permit to obtain the different variants for each structure in order to select the physically realizable solution and can be used in broad range of frequency ratio and power division ratio. For verification, three different dual-band couplers, which are operating at 2.4/3.9 GHz with different coupling coefficients (one with 3/6 dB, and 10/3 dB two others are designed, simulated, fabricated and tested. The measured results are in good agreement with the simulated ones.

  6. Comparison of coaxial higher order mode couplers for the CERN Superconducting Proton Linac study

    CERN Document Server

    AUTHOR|(CDS)2085329; Gerigk, Frank; Van Rienen, Ursula

    2017-01-01

    Higher order modes (HOMs) may affect beam stability and refrigeration requirements of superconducting proton linacs such as the Superconducting Proton Linac, which is studied at CERN. Under certain conditions beam-induced HOMs can accumulate sufficient energy to destabilize the beam or quench the superconducting cavities. In order to limit these effects, CERN considers the use of coaxial HOM couplers on the cutoff tubes of the 5-cell superconducting cavities. These couplers consist of resonant antennas shaped as loops or probes, which are designed to couple to potentially dangerous modes while sufficiently rejecting the fundamental mode. In this paper, the design process is presented and a comparison is made between various designs for the high-beta SPL cavities, which operate at 704.4 MHz. The rf and thermal behavior as well as mechanical aspects are discussed. In order to verify the designs, a rapid prototype for the favored coupler was fabricated and characterized on a low-power test-stand.

  7. On the Importance of Symmetrizing RF Coupler Fields for Low Emittance Beams

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zenghai; Zhou, Feng; Vlieks, Arnold; Adolphsen, Chris; /SLAC

    2011-06-23

    The input power of accelerator structure is normally fed through a coupling slot(s) on the outer wall of the accelerator structure via magnetic coupling. While providing perfect matching, the coupling slots may produce non-axial-symmetric fields in the coupler cell that can induce emittance growth as the beam is accelerated in such a field. This effect is especially important for low emittance beams at low energies such as in the injector accelerators for light sources. In this paper, we present studies of multipole fields of different rf coupler designs and their effect on beam emittance for an X-band photocathode gun being jointly designed with LLNL, and X-band accelerator structures. We will present symmetrized rf coupler designs for these components to preserve the beam emittance.

  8. Low-loss highly tolerant flip-chip couplers for hybrid integration of Si3N4 and polymer waveguides

    NARCIS (Netherlands)

    Mu, J.; Alexoudi, T.; Yong, Y.S.; Vázquez-Córdova, S.A.; Dijkstra, M.; Worhoff, K.; Duis, J.; Garcia Blanco, S.M.

    2016-01-01

    In this letter, low-loss and highly fabrication-tolerant flip-chip bonded vertical couplers under single-mode condition are demonstrated for the integration of a polymer waveguide chip onto the Si3N4/SiO2 passive platform. The passively aligned vertical couplers have a lateral misalignment between p

  9. High brightness sub-nanosecond Q-switched laser using volume Bragg gratings

    Science.gov (United States)

    Anderson, Brian M.; Hale, Evan; Venus, George; Ott, Daniel; Divliansky, Ivan; Glebov, Leonid

    2016-03-01

    The design of Q-switched lasers capable of producing pulse widths of 100's of picoseconds necessitates the cavity length be shorter than a few centimeters. Increasing the amount of energy extracted per pulse requires increasing the mode area of the resonator that for the same cavity length causes exciting higher order transverse modes and decreasing the brightness of the output radiation. To suppress the higher order modes of these multimode resonators while maintaining the compact cavity requires the use of intra-cavity angular filters. A novel Q-switched laser design is presented using transmitting Bragg gratings (TBGs) as angular filters to suppress the higher order transverse modes. The laser consists of a 5 mm thick slab of Nd:YAG, a 3 mm thick slab of Cr:YAG with a 20% transmission, one TBG aligned to suppress the higher order modes along the x-axis, and a 40% output coupler. The gratings are recorded in photo-thermo-refractive (PTR) glass, which has a high damage threshold that can withstand both the high peak powers and high average powers present within the resonator. Using a 4.1 mrad TBG in a 10.8 mm long resonator with an 800μm x 400 μm pump beam, a nearly diffraction limited beam quality of M2 = 1.3 is obtained in a 0.76 mJ pulse with a pulse width of 614 ps.

  10. All-optical switching using a new photonic crystal directional coupler

    Directory of Open Access Journals (Sweden)

    B. Vakili

    2015-07-01

    Full Text Available In this paper all-optical switching in a new photonic crystal directional coupler is performed.  The structure of the switch consists of a directional coupler and a separate path for a control signal called “control waveguide”. In contrast to the former reported structures in which the directional couplers are made by removing a row of rods entirely, the directional coupler in our optical switch is constructed by two reduced-radius line-defect waveguides separated by the control waveguide. Furthermore, in our case the background material has the nonlinear Kerr property. Therefore, in the structure of this work, no frequency overlap occurs between the control waveguide mode and the directional coupler modes. It is shown that such a condition provides a very good isolation between the control and the probe signals at the output ports. In the control waveguide, nonlinear Kerr effect causes the required refractive index change by the presence of a high power control (pump signal. Even and odd modes of the coupler are investigated by applying the distribution of the refractive index change in the nonlinear region of a super-cell so that a switching length of about 94 µm is obtained at the wavelength of 1.55 µm. Finally, all-optical switching of the 1.55 µm probe signal using a control signal at the wavelength of 1.3 µm, is simulated through the finite-difference time-domain method, where both signals are desirable in optical communication systems. A very high extinction ratio of 67 dB is achieved and the temporal characteristics of the switch are demonstrated.

  11. The spectral combination characteristic of grating and the bi-grating diffraction imaging effect

    Institute of Scientific and Technical Information of China (English)

    ZHANG WeiPing; HE XiaoRong

    2007-01-01

    This paper reports on a new property of grating,namely spectral combination,and on bi-grating diffraction imaging that is based on spectral combination.The spectral combination characteristic of a grating is the capability of combining multiple light beams of different wavelengths incident from specific angles into a single beam.The bi-grating diffraction imaging is the formation of the image of an object with two gratings: the first grating disperses the multi-color light beams from the object and the second combines the dispersed light beams to form the image.We gave the conditions necessary for obtaining the spectral combination.We also presented the equations that relate the two gratings' spatial frequencies,diffraction orders and positions necessary for obtaining the bi-grating diffraction imaging.

  12. Exact control of parity-time symmetry in periodically modulated nonlinear optical couplers

    CERN Document Server

    Yang, Baiyuan; Hu, QiangLin; Yu, XiaoGuang

    2016-01-01

    We propose a mechanism for realization of exact control of parity-time (PT) symmetry by using a periodically modulated nonlinear optical coupler with balanced gain and loss. It is shown that for certain appropriately chosen values of the modulation parameters, we can construct a family of exact analytical solutions for the two-mode equations describing the dynamics of such nonlinear couplers. These exact solutions give explicit examples that allow us to precisely manipulate the system from nonlinearity-induced symmetry breaking to PT symmetry, thus providing an analytical approach to the all-optical signal control in nonlinear PT-symmetric structures.

  13. Cost-Effectiveness Comparison of Coupler Designs of Wireless Power Transfer for Electric Vehicle Dynamic Charging

    Directory of Open Access Journals (Sweden)

    Weitong Chen

    2016-11-01

    Full Text Available This paper presents a cost-effectiveness comparison of coupler designs for wireless power transfer (WPT, meant for electric vehicle (EV dynamic charging. The design comparison of three common types of couplers is first based on the raw material cost, output power, transfer efficiency, tolerance of horizontal offset, and flux density. Then, the optimal cost-effectiveness combination is selected for EV dynamic charging. The corresponding performances of the proposed charging system are compared and analyzed by both simulation and experimentation. The results verify the validity of the proposed dynamic charging system for EVs.

  14. Comparative electromagnetic analysis of ridge waveguide transitions for RF power couplers

    Science.gov (United States)

    Kumar, Rajesh; Singh, P.; Mathur, Pratigya; Kumar, Girish

    2014-02-01

    Ridge waveguide transitions have been used in the high power couplers of many ongoing high intensity proton accelerator projects worldwide. Because of their smaller size and high energy densities, they require strict dimensional tolerances during fabrication and operating conditions. In order to study their electromagnetic characteristics, two different types of transitions with a straight ridge and a tapered ridge are compared using full wave simulations. Apart from the return loss and resonant frequency variation with dimensions, comparative studies on the phase shift, insertion losses, electric and magnetic field distributions and multipacting are also reported. This analysis will be useful in selecting the appropriate ridge waveguide transition for the RF couplers of accelerator cavities.

  15. Mode-evolution-based coupler for high saturation power Ge-on-Si photodetectors.

    Science.gov (United States)

    Byrd, Matthew J; Timurdogan, Erman; Su, Zhan; Poulton, Christopher V; Fahrenkopf, Nicholas M; Leake, Gerald; Coolbaugh, Douglas D; Watts, Michael R

    2017-02-15

    We propose a mode-evolution-based coupler for high saturation power germanium-on-silicon photodetectors. This coupler uniformly illuminates the intrinsic germanium region of the detector, decreasing saturation effects, such as carrier screening, observed at high input powers. We demonstrate 70% more photocurrent generation (9.1-15.5 mA) and more than 40 times higher opto-electrical bandwidth (0.7-31 GHz) than conventional butt-coupled detectors under high-power illumination. The high-power and high-speed performance of the device, combined with the compactness of the coupling method, will enable new applications for integrated silicon photonics systems.

  16. A new demodulation technique for optical fiber interferometric sensors with [3×3] directional couplers

    Institute of Scientific and Technical Information of China (English)

    Tingting Liu; Jie Cui; Desheng Chen; Ling Xiao; Dexing Sun

    2008-01-01

    2Optical fiber interferometric sensors based on [3 × 3] couplers have been used in many fields. A new technique is proposed to demodulate output signals of this kind of sensors. The technique recovers the signal of interest by fitting coefficients of elliptic (Lissajous) curves between each fiber pair. Different from other approaches, this technique eliminates the dependence on the idealization of [3 × 3] coupler, provides enhanced tolerance to the variance of photoelectric converters, and is anti-polarization in a certain extent. The main algorithm has been successfully demonstrated both by numerical simulation and experimental result.

  17. Topology-optimized slow-light couplers for ring-shaped photonic crystal waveguide

    DEFF Research Database (Denmark)

    Pu, Minhao; Yang, Lirong; Frandsen, L. H.;

    2010-01-01

    We demonstrate a topology-optimized coupler for a ring-shaped photonic crystal waveguide to improve the coupling of light located in the slow-light regime. An enhancement of the coupling efficiency of up to 2.5 dB is experimentally demonstrated.......We demonstrate a topology-optimized coupler for a ring-shaped photonic crystal waveguide to improve the coupling of light located in the slow-light regime. An enhancement of the coupling efficiency of up to 2.5 dB is experimentally demonstrated....

  18. Optical microwave generation using two parallel DFB lasers integrated with Y-branch waveguide coupler

    Institute of Scientific and Technical Information of China (English)

    Xie Hong-Yun; Wang Lu; Zhao Ling-Juan; Zhu Hong-Liang; Wang Wei

    2007-01-01

    A new device of two parallel distributed feedback (DFB) lasers integrated monolithically with Y-branch waveguide coupler was fabricated by means of quantum well intermixing. Optical microwave signal was generated in the Y-branch waveguide coupler through frequency beating of the two laser modes coming from two DFB laser in parallel, which had a small difference in frequency. Continuous rapid tuning of optical microwave signal from 13 to 42 GHz were realized by adjusting independently the driving currents injected into the two DFB lasers.

  19. Nanoporous Polymeric Grating-Based Biosensors

    KAUST Repository

    Gao, Tieyu

    2012-05-02

    We demonstrate the utilization of an interferometrically created nanoporous polymeric gratings as a platform for biosensing applications. Aminopropyltriethoxysilane (APTES)-functionalized nanoporous polymeric gratings was fabricated by combining holographic interference patterning and APTES-functionalization of pre-polymer syrup. The successful detection of multiple biomolecules indicates that the biofunctionalized nanoporous polymeric gratings can act as biosensing platforms which are label-free, inexpensive, and applicable as high-throughput assays. Copyright © 2010 by ASME.

  20. Plasmonic Transmission Gratings – Fabrication and Characterization

    DEFF Research Database (Denmark)

    Sierant, Aleksandra; Jany, Benedykt; Bartoszek-Bober, Dobrosława

    realization is given by the use of a metallic diffraction grating, where the diffracted light couples to the SPP. Here, we propose metallic periodic transmission gratings, processed onto a glass substrate, with various periods and fill factors. The gratings are milled in a plain gold layer with a focused ion...... beam (FIB) microscope, using gallium and a neutralizing electron beam. We investigate the SPP coupling strength with respect to varying top layers and under collimated, oblique-angled excitation, with respect to the effect of finite gratings as opposed to perfect periodicity. We characterize...

  1. Biosensing with optical fiber gratings

    Directory of Open Access Journals (Sweden)

    Chiavaioli Francesco

    2017-06-01

    Full Text Available Optical fiber gratings (OFGs, especially long-period gratings (LPGs and etched or tilted fiber Bragg gratings (FBGs, are playing an increasing role in the chemical and biochemical sensing based on the measurement of a surface refractive index (RI change through a label-free configuration. In these devices, the electric field evanescent wave at the fiber/surrounding medium interface changes its optical properties (i.e. intensity and wavelength as a result of the RI variation due to the interaction between a biological recognition layer deposited over the fiber and the analyte under investigation. The use of OFG-based technology platforms takes the advantages of optical fiber peculiarities, which are hardly offered by the other sensing systems, such as compactness, lightness, high compatibility with optoelectronic devices (both sources and detectors, and multiplexing and remote measurement capability as the signal is spectrally modulated. During the last decade, the growing request in practical applications pushed the technology behind the OFG-based sensors over its limits by means of the deposition of thin film overlays, nanocoatings, and nanostructures, in general. Here, we review efforts toward utilizing these nanomaterials as coatings for high-performance and low-detection limit devices. Moreover, we review the recent development in OFG-based biosensing and identify some of the key challenges for practical applications. While high-performance metrics are starting to be achieved experimentally, there are still open questions pertaining to an effective and reliable detection of small molecules, possibly up to single molecule, sensing in vivo and multi-target detection using OFG-based technology platforms.

  2. Fiber Bragg Grating Based Thermometry

    CERN Document Server

    Ahmed, Zeeshan; Guthrie, William; Quintavalle, John

    2016-01-01

    In recent years there has been considerable interest in developing photonic temperature sensors such as the Fiber Bragg gratings (FBG) as an alternative to resistance thermometry. In this study we examine the thermal response of FBGs over the temperature range of 233 K to 393 K. We demonstrate, in a hermetically sealed dry Argon environment, that FBG devices show a quadratic dependence on temperature with expanded uncertainties (k = 2) of ~500 mK. Our measurements indicate that the combined measurement uncertainty is dominated by uncertainty in determining the peak center fitting and by thermal aging of polyimide coated fibers.

  3. Final Commissioning of the MICE RF Module Prototype with Production Couplers

    Energy Technology Data Exchange (ETDEWEB)

    Torun, Yagmur [IIT, Chicago; Anderson, Terry [Fermilab; Backfish, Michael [Fermilab; Bowring, Daniel [Fermilab; Freemire, Ben [IIT, Chicago (main); Hart, Terrence [Mississippi U.; Kochemirovskiy, Alexey [Illinois U., Chicago; Lane, Peter [IIT, Chicago; Luo, Tianhuan [LBNL, Berkeley; Moretti, Alfred [Fermilab; Neuffer, David [Fermilab; Peterson, David [Fermilab; Popovic, Milorad [Fermilab; Yonehara, Katsuya [Fermilab

    2016-06-01

    We report operational experience from the prototype RF module for the Muon Ionization Cooling Experiment (MICE) with final production couplers at Fermilab's MuCool Test Area. This is the last step in fully qualifying the RF modules for operation in the experiment at RAL.

  4. The secondary electron emission coefficient of the material for the superconducting cavity input coupler

    CERN Document Server

    Kijima, Y; Furuya, T; Michizono, S I; Mitsunobu, S; Noer, R J

    2002-01-01

    The secondary electron emission (SEE) coefficients have been measured, for materials used in the coupler for KEKB superconducting cavities, i.e. Copper, Stainless steel plated with Copper, Niobium and Ceramic. We show that the electron bombardment is effective in decreasing the SEE coefficient of the metal surfaces, and the TiN coating and window fabrication processes influence the secondary electron yield. (author)

  5. Performance of Polarizers and Coupler in an All Polarization Maintaining Fiber Interferometer

    Institute of Scientific and Technical Information of China (English)

    CHEN Zhe; LIAO Yanbiao; HU Yongrning; LI Xiujian; MENG Zhou

    2000-01-01

    It is given mathematical models and analyze the performance of polarizers and coupler in an all polarization maintaining fiber (PMF) Michelson interferometer. The optical coherent signal to noise ratio (CSNR) of the interferometer is calculated by means of the Jones matrix with cross coupling matrix elements.

  6. Research on Design of Plate-type Electromagnetic Coupler in Underwater Inductive Power Transmission

    Directory of Open Access Journals (Sweden)

    Qu Li-yan

    2015-01-01

    Full Text Available Magnetic coupler has a good application in the field of underwater sensor. Magnetic coupler at work, interference by underwater complex situation, stability and efficiency of charging device of the gap is larger fluctuations. The traditional electromagnetic coupling is charging for the stability of the clearance to demand higher. Charging for underwater, as a result of the existence of ocean currents, electromagnetic coupling clearance may not remain very stable. When there is deviation gap, a larger electromagnetic coupling performance deviation. On this particular problem, it puts forward the design method of a new type of plate type electromagnetic coupling. First of all, the leakage inductance of the finite element method to calculate system and excitation inductance, establish electromagnetic coupler with compensation capacitor equivalent circuit, and the primary circuit and secondary circuit was designed. On the basis, the voltage gain and efficiency of the system are carrying on the theoretical derivation and calculation. The simulation experimental results show that the magnetic coupler has a stable voltage gain and charging efficiency, when the partial core within 10 mm, voltage gain remains steady at 5.8%, efficiency remain at around 90%.

  7. Solitary Wave Generation from Constant Continuous Wave in Asymmetric Oppositely Directed Waveguide Coupler

    Directory of Open Access Journals (Sweden)

    Kazantseva E.V.

    2015-01-01

    Full Text Available In a model which describes asymmetric oppositely directed nonlinear coupler it was observed in numerical simulations a phenomenon of solitary wave generation from the input constant continuous wave set at the entrance of a waveguide with negative refraction. The period of solitary wave formation decreases with increase of the continuum wave amplitude.

  8. Cpl6: The New Extensible, High-Performance Parallel Coupler forthe Community Climate System Model

    Energy Technology Data Exchange (ETDEWEB)

    Craig, Anthony P.; Jacob, Robert L.; Kauffman, Brain; Bettge,Tom; Larson, Jay; Ong, Everest; Ding, Chris; He, Yun

    2005-03-24

    Coupled climate models are large, multiphysics applications designed to simulate the Earth's climate and predict the response of the climate to any changes in the forcing or boundary conditions. The Community Climate System Model (CCSM) is a widely used state-of-art climate model that has released several versions to the climate community over the past ten years. Like many climate models, CCSM employs a coupler, a functional unit that coordinates the exchange of data between parts of climate system such as the atmosphere and ocean. This paper describes the new coupler, cpl6, contained in the latest version of CCSM,CCSM3. Cpl6 introduces distributed-memory parallelism to the coupler, a class library for important coupler functions, and a standardized interface for component models. Cpl6 is implemented entirely in Fortran90 and uses Model Coupling Toolkit as the base for most of its classes. Cpl6 gives improved performance over previous versions and scales well on multiple platforms.

  9. Design and optimization of mechanically down-doped terahertz fiber directional couplers

    DEFF Research Database (Denmark)

    Bao, Hualong; Nielsen, Kristian; Rasmussen, Henrik K.;

    2014-01-01

    We present a thorough practical design optimization of broadband low loss, terahertz (THz) photonic crystal fiber directional couplers in which the two cores are mechanically down-doped with a triangular array of air holes. A figure of merit taking both the 3-dB bandwidth and loss of the coupler...... into account, is used for optimization of the structure parameters, given by the diameter and pitch of the cladding (d and Λ) and of the core (dc and Λc) air-hole structure. The coupler with Λ = 498.7 μm, dc= 324.2 μm, Λc = 74.8 μm, and dc = 32.5 μm is found to have the best performance at a center frequency...... of 1THz, with a bandwidth of 0.25 THz and a total device loss of 9.2 dB. The robustness of the optimum coupler to structural changes is investigated. © 2014 Optical Society of America....

  10. InGaN directional coupler made with a one-step etching technique

    Science.gov (United States)

    Gao, Xumin; Yuan, Jialei; Yang, Yongchao; Zhang, Shuai; Shi, Zheng; Li, Xin; Wang, Yongjin

    2017-06-01

    We propose, fabricate and characterize an on-chip integration of light source, InGaN waveguide, directional coupler and photodiode, in which AlGaN layers are used as top and bottom optical claddings to form an InGaN waveguide for guiding the in-plane emitted light from the InGaN/GaN multiple-quantum-well light-emitting diode (MQW-LED). The difference in etch rate caused by different exposure windows leads to an etching depth discrepancy using the one-step etching technique, which forms the InGaN directional coupler with the overlapped underlying slab. Light propagation results directly confirm effective light coupling in the InGaN directional coupler, which is achieved through high-order guided modes. The InGaN waveguide couples the modulated light from the InGaN/GaN MQW-LED and transfers part of light to the coupled waveguide via the InGaN directional coupler. The in-plane InGaN/GaN MQW-photodiode absorbs the guided light by the coupled InGaN waveguide and induces the photocurrent. The on-chip InGaN photonic integration experimentally demonstrates an in-plane light communication with a data transmission of 50 Mbps.

  11. Modeling of racetrack-resonator add-drop filters with arbitrary nonlinear directional couplers.

    Science.gov (United States)

    Gómez-Alcalá, Rafael; Fraile-Peláez, F Javier; Chamorro-Posada, Pedro; Díaz-Otero, Francisco J

    2012-06-01

    In this Letter we employ the general coupled-mode equations of the nonlinear directional coupler and demonstrate that the switching characteristics of prototypical nonlinear racetrack-resonator structures may differ considerably from those obtained when the standard, generally incorrect, coupled-mode equations are used.

  12. A Compact, High Power Capable, and Tunable High Directivity Microstrip Coupler.

    Science.gov (United States)

    Sohn, Sung-Min; Gopinath, Anand; Vaughan, John Thomas

    2016-10-01

    A coupler is an indispensable component to sample the forward and reflected power for the real-time radio frequency (RF) power monitoring system. The directivity of a coupler is a critical factor to achieve accurate RF power measurements. This paper proposes a microstrip coupler with a tunable high directivity circuit to accurately measure the reflected RF power. The directivity tuner composed of passive components adjusts phase and amplitude of the coupled RF signal, and cancel out the leakage signal from the RF input port at the coupled reflection port. The experimental results, which agree with simulation results, show that the microstrip coupler with the directivity tuner circuit has a compact size (~ 0.07 λg x 0.05 λg), high power capability (up to 1 kW), and high directivities (more than 40 dB) at operating frequency bands (f = 297.3 MHz, 400 MHz, and 447 MHz, respectively) for magnetic resonance imaging (MRI) applications.

  13. Characteristics of WDM Couplers Based on 80 μm Cladding Fiber

    Institute of Scientific and Technical Information of China (English)

    Hyunsook; Shin; Woojin; Shin; Manjung; Han; Kyoungrok; Kim; Seungryong; Han; Yunsong; Jeong; K.; Oh

    2003-01-01

    We have fabricated 1310/1550 and 1480/1550nm WDM couplers using a fiber of 80μm cladding diameter, whose tapering length is shortened by 4~8mm for the identical coupling strength compared to those of 125μm cladding fibers. We also report their splicing loss to conventional single mode fibers.

  14. Finite Element Analysis of RF Coupler in Normal-Low Temperature

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hansol; Lee, Hak Yong; Park, Chan; Lee, Jaeyeol; Lim, Dong Yeal; Yoo, Jeonghoon [Yonsei University, Seoul (Korea, Republic of); Hyun, Myung Wook [Institute of Basic Science, Daejeon (Korea, Republic of)

    2014-10-15

    A heavy ion accelerator is a device that accelerates heavy ions in the radio frequency (RF) range. The electric field that flows into the RF cavity continuously accelerates heavy ions in accordance with the phase of the input electromagnetic wave. For the purpose, it is necessary to design a coupler shape that can stably transfer the RF wave into the cavity. The RF coupler in a heavy ion accelerator has a large temperature difference between the input port and output port, which radiates the RF waves. It is necessary to consider the heat deflection on the RF coupler that occurs as a result of the rapid temperature gradient from an ultra-low temperature about 0 K to a room temperature about 300 K. The purpose of this study was to improve the system performance through an analysis of the intensity of the output electric field and temperature distribution considering various shapes of the RF coupler, along with an analysis of the durability considering the heat deflection and heat loss.

  15. Novel Fused Taper 1x4 Star Coupler for Full-Band Operation

    Institute of Scientific and Technical Information of China (English)

    Masakazu; Ohashi; Hideki; Sasaki; Ryoukichi; Matsumoto; Daiichiro; Tanaka; Akira; Wada

    2003-01-01

    A novel fused taper 1×4 coupler for full-band operation is proposed. Wavelength flattened characteristics and excellent branching uniformity less than 0.4 dB have been achieved in wavelength range from 1200 nm to 1700 nm.

  16. Performance improvement to silicon-on-insulator waveguide directional-coupler based devices

    Science.gov (United States)

    Sun, DeGui; Hasan, Imad; Abdul-Majid, Sawsan; Vandusen, Rob; Zheng, Qi; Hussien, Ali; Wang, Chunxia; Hu, Zhongming; Tarr, T. Garry; Hall, Trevor J.

    2010-10-01

    For the SOI-waveguide directional coupler (WDC), optical access loss (OAL) and polarization dependence (PD) are two critical performance specifications which seriously affect the adoptability and deployment of a device, including optical on-chip loss (OCL), polarization dependent loss (PDL) and extinction ratio of a 3dB-coupler based device. In this work, using a commercial software tool - FIMMPROP, the performance of an SOI-WDC is simulated. Simulations find that the curved waveguides for the turning sections of a 3dB WDC not only enlarge the footprint size, but also seriously deteriorate the device performance. For instance, the two curved waveguide sections of a WDC induce an unpredictably large change in the 3dB-coupling length, increase an OAL of 0.4-0.9dB, and seriously deteriorate the PD, and these performance changes radically depend on rib size. After a corner-turning mirror (CTM) structure is introduced to a 3dB SOI-WDC, the experiments show both the footprint length and 3dB-coupling length are unchanged, the OAL of the 3dB coupler is only 0.5dB which is close to the simulation value. Therefore, for a 3dB-coupler based Mach-Zehnder interference (MZI) structure, the OCL will be controlled to be <1.0dB in device design and will not depend on rib size.

  17. Stability Analysis of Fixed points in a Parity-time symmetric coupler with Kerr nonlinearity

    CERN Document Server

    Deka, Jyoti Prasad

    2016-01-01

    We report our study on nonlinear parity-time (PT) symmetric coupler from a dynamical perspective. In the linear regime, the differential equations governing the dynamics of the coupler, under some parametric changes, can be solved exactly. But with the inclusion of nonlinearity, analytical solution of the system is a rather complicated job. And the sensitiveness of the system on the initial conditions is yet another critical issue. To circumvent the situation, we have employed the mathematical framework of nonlinear dynamics. Considering the parity-time threshold of the linear PT-coupler as the reference point, we find that in nonlinear coupler the parity-time symmetric threshold governs the existence of fixed points. We have found that the stability of the ground state undergoes a phase transition when the gain/loss coefficient is increased from zero to beyond the PT threshold. In the unbroken PT regime, we find that the instabilities in the initial launch conditions can trigger an exponential growth and dec...

  18. Dynamic balancing of a single crank-double slider mechanism with symmetrically moving couplers

    NARCIS (Netherlands)

    van der Wijk, V.; Herder, Justus Laurens; Pisla, Doina; Ceccarelli, Marco; Husty, Manfred; Corves, Burkhard

    2010-01-01

    This article presents a systematic investigation of the dynamic balancing of a singlecrank-double slider mechanism of which the coupler links have symmetric motion. From the equationsof the linear momentum and angular momentum the force balance conditions and momentbalance conditions are derived. Bo

  19. The Experimental Study on Acousto-optic Modulation Based on Single-mode Fiber Fused Coupler

    Institute of Scientific and Technical Information of China (English)

    Liu Guoxiang; Hu Li; Ye Kunzhen; Lin Weigan

    2002-01-01

    In-line acoustic-optic (AO) modulation experiments were demonstrated based on the acoustic-optic effect in optical fiber fused taper couplers.About 73%,64%,and 61% modulation have been achieved at frequencies of 0.169 MHz,0.367 MHz and 0.521 MHz with an electrical driving power less than 10 mW,respectively.

  20. Comparative Simulation Studies of Multipacting in Higher-Order-Mode Couplers of Superconducting RF Cavities

    Energy Technology Data Exchange (ETDEWEB)

    Li, Y. M. [Peking University, Beijing (China); Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Liu, Kexin [Peking University, Beijing (China); Geng, Rongli [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)

    2014-02-01

    Multipacting (MP) in higher-order-mode (HOM) couplers of the International Linear Collider (ILC) baseline cavity and the Continuous Electron Beam Accelerator Facility (CEBAF) 12 GeV upgrade cavity is studied by using the ACE3P suites, developed by the Advanced Computations Department at SLAC. For the ILC cavity HOM coupler, the simulation results show that resonant trajectories exist in three zones, corresponding to an accelerating gradient range of 0.6-1.6 MV/m, 21-34 MV/m, 32-35 MV/m, and > 40MV/m, respectively. For the CEBAF 12 GeV upgrade cavity HOM coupler, resonant trajectories exist in one zone, corresponding to an accelerating gradient range of 6-13 MV/m. Potential implications of these MP barriers are discussed in the context of future high energy pulsed as well as medium energy continuous wave (CW) accelerators based on superconducting radio frequency cavities. Frequency scaling of MP's predicted in HOM couplers of the ILC, CBEAF upgrade, SNS and FLASH third harmonic cavity is given and found to be in good agreement with the analytical result based on the parallel plate model.

  1. The spectral combination characteristic of grating and the bi-grating diffraction imaging effect

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper reports on a new property of grating, namely spectral combination, and on bi-grating diffraction imaging that is based on spectral combination. The spectral combination characteristic of a grating is the capability of combining multiple light beams of different wavelengths incident from specific angles into a single beam. The bi-grating diffraction imaging is the formation of the image of an object with two gratings: the first grating disperses the multi-color light beams from the object and the second combines the dispersed light beams to form the image. We gave the conditions necessary for obtaining the spectral combination. We also presented the equations that relate the two gratings’ spatial frequencies, diffraction orders and positions necessary for obtaining the bi-grating diffraction imaging.

  2. Diffractive Optics of Anisotropic Polarization Gratings

    NARCIS (Netherlands)

    Xu, M.

    2009-01-01

    Diffraction gratings are being used to manipulate light in many different applications, such as in flat panel display systems, modern lighting systems, and optical recording. Diffraction gratings can be made polarization selective due to form birefringence. An alternative approach to polarization

  3. Antireflective characteristics of hemispherical grid grating

    Institute of Scientific and Technical Information of China (English)

    REN Zhibin; JIANG Huilin; LIU Guojun; SUN Qiang

    2005-01-01

    In this paper, the optical characteristics of new type hemispherical grid subwavelength grating are studied by using multi-level column structure approximation and rigorous coupled-wave analysis. This kind of grating could be fabricated by chemical methods, thus simplifying the fabrication technology of subwavelength gratings for visible light. By computer simulation and calculation, the hemispherical grid subwavelength gratings are proved to have antireflective characteristics. Two design schemes of this kind of grating are presented. In the first scheme, the grating could achieve a reflectivity as low as 3.4416×10-7, which can be adapted to 0.46―0.7 μm of visible waveband and ±12° incident angle field. In the second scheme, the grating can achieve a reflectivity as low as 3.112×10-4 and adapted to the whole visible waveband and ±23° incident angle field. The application field of the latter scheme is wider than that of the former. The results of this paper could provide reference for the applications of the hemispherical grid subwavelength gratings for the visible waveband.

  4. Straw combustion on slow-moving grates

    DEFF Research Database (Denmark)

    Kær, Søren Knudsen

    2005-01-01

    Combustion of straw in grate-based boilers is often associated with high emission levels and relatively poor fuel burnout. A numerical grate combustion model was developed to assist in improving the combustion performance of these boilers. The model is based on a one-dimensional ‘‘walking...

  5. The Flexibility of Pusher Furnace Grate

    Directory of Open Access Journals (Sweden)

    Słowik J.A.

    2016-12-01

    Full Text Available The lifetime of guide grates in pusher furnaces for heat treatment could be increased by raising the flexibility of their structure through, for example, the replacement of straight ribs, parallel to the direction of grate movement, with more flexible segments. The deformability of grates with flexible segments arranged in two orientations, i.e. crosswise (perpendicular to the direction of compression and lengthwise (parallel to the direction of compression, was examined. The compression process was simulated using SolidWorks Simulation program. Relevant regression equations were also derived describing the dependence of force inducing the grate deformation by 0.25 mm ‒ modulus of grate elasticity ‒ on the number of flexible segments in established orientations. These calculations were made in Statistica and Scilab programs. It has been demonstrated that, with the same number of segments, the crosswise orientation of flexible segments increases the grate structure flexibility in a more efficient way than the lengthwise orientation. It has also been proved that a crucial effect on the grate flexibility has only the quantity and orientation of segments (crosswise / lengthwise, while the exact position of segments changes the grate flexibility by less than 1%.

  6. A narrow-line Erbium-doped fiber laser and its application for testing fiber Bragg gratings

    Science.gov (United States)

    Guzmán-Chávez, A. D.; Barmenkov, Yu. O.; Kir'yanov, A. V.; Mendoza-Santoyo, F.

    2009-09-01

    We inspect the spectral features of a diode-pumped Erbium-doped fiber laser (EDFL) with a Fabry-Perot cavity composed of a wavelength-selective coupler in the form of fiber Bragg grating (FBG) and wavelength-insensitive Faraday rotator mirror (FRM). High accuracy for the spectral measurements is provided with the use of an optical heterodyne scheme where the EDFL output is mixed with radiation from a narrow-line semiconductor laser, allowing the detection of the EDFL spectra with a sub-pm resolution. The heterodyne scheme permits precise measurements of the EDFL line-width as a function of the cavity length and pump power. It is worth noticing a narrow-line (a few pm) operation of the EDFL with a short length (pump power over the laser threshold. The spectral response of the EDFL to a slow sinusoidal modulation of a physical length of the FBG coupler is analyzed and it is shown that as high as ˜1-nm modulation of the EDFL optical spectrum is attainable at maximal modulation amplitudes. The narrow-line EDFL with a modulated generation wavelength is hereby demonstrated to be a tool for high-resolution measurements of reflection spectra of FBGs, which is to the best of our knowledge a novel application of the EDFL.

  7. Four-Pass Coupler for Laser-Diode-Pumped Solid-State Laser

    Science.gov (United States)

    Coyle, Donald B.

    2008-01-01

    A four-pass optical coupler affords increased (in comparison with related prior two-pass optical couplers) utilization of light generated by a laser diode in side pumping of a solid-state laser slab. The original application for which this coupler was conceived involves a neodymium-doped yttrium aluminum garnet (Nd:YAG) crystal slab, which, when pumped by a row of laser diodes at a wavelength of 809 nm, lases at a wavelength of 1,064 nm. Heretofore, typically, a thin laser slab has been pumped in two passes, the second pass occurring by virtue of reflection of pump light from a highly reflective thin film on the side opposite the side through which the pump light enters. In two-pass pumping, a Nd:YAG slab having a thickness of 2 mm (which is typical) absorbs about 84 percent of the 809-nm pump light power, leaving about 16 percent of the pump light power to travel back toward the laser diodes. This unused power can cause localized heating of the laser diodes, thereby reducing their lifetimes. Moreover, if the slab is thinner than 2 mm, then even more unused power travels back toward the laser diodes. The four-pass optical coupler captures most of this unused pump light and sends it back to the laser slab for two more passes. As a result, the slab absorbs more pump light, as though it were twice as thick. The gain and laser cavity beam quality of a smaller laser slab in conjunction with this optical coupler can thus be made comparable to those of a larger two-pass-pumped laser slab.

  8. Reflectivity-modulated grating-mirror

    DEFF Research Database (Denmark)

    2012-01-01

    The invention relates to vertical cavity lasers (VCL) incorporating a reflectivity-modulated grating mirror (1) for modulating the laser output. A cavity is formed by a bottom mirror (4), an active region (3), and an outcoupling top grating mirror (1) formed by a periodic refractive index grating...... to the oscillation axis. A modulated voltage (91) is applied in reverse bias between the n- and p-doped layers to modulate the refractive index of the electrooptic material layer (12) and thereby the reflectivity spectrum of the grating mirror (1). The reflectivity of the grating mirror (1) can be modulated between...... a reflectivity with little or no out coupling and a reflectivity with normal out coupling, wherein lasing in the VCL is supported at both the first and the second reflectivity. As the out coupling mirror modulates the output, the lasing does not need to be modulated, and the invention provides the advantage...

  9. Alignment free characterization of 2D gratings

    CERN Document Server

    Madsen, Morten Hannibal; Hansen, Poul-Erik; Jørgensen, Jan Friis

    2015-01-01

    Fast characterization of 2-dimensional gratings is demonstrated using a Fourier lens optical system and a differential optimization algorithm. It is shown that both the grating specific parameters such as the basis vectors and the angle between them and the alignment of the sample, such as the rotation of the sample around the x-, y-, and z-axis, can be deduced from a single measurement. More specifically, the lattice vectors and the angle between them have been measured, while the corrections of the alignment parameters are used to improve the quality of the measurement, and hence reduce the measurement uncertainty. Alignment free characterization is demonstrated on both a 2D hexagonal grating with a period of 700 nm and a checkerboard grating with a pitch of 3000 nm. The method can also be used for both automatic alignment and in-line characterization of gratings.

  10. Grating droplets with a mesh

    Science.gov (United States)

    Soto, Dan; Le Helloco, Antoine; Clanet, Cristophe; Quere, David; Varanasi, Kripa

    2016-11-01

    A drop thrown against a mesh can pass through its holes if impacting with enough inertia. As a result, although part of the droplet may remain on one side of the sieve, the rest will end up grated through the other side. This inexpensive method to break up millimetric droplets into micrometric ones may be of particular interest in a wide variety of applications: enhancing evaporation of droplets launched from the top of an evaporative cooling tower or preventing drift of pesticides sprayed above crops by increasing their initial size and atomizing them at the very last moment with a mesh. In order to understand how much liquid will be grated we propose in this presentation to start first by studying a simpler situation: a drop impacting a plate pierced with a single off centered hole. The study of the role of natural parameters such as the radius drop and speed or the hole position, size and thickness allows us to discuss then the more general situation of a plate pierced with multiple holes: the mesh.

  11. Enhanced resolution of a POF-based refractometer using a novel hybrid silica-fiber POF directional coupler

    Science.gov (United States)

    Farrell, Gerald; Gao, Cheng

    2008-04-01

    For a plastic optical fiber based refractometer system the influence of the directivity of the fiber coupler on the achievable resolution is analysed. It is also shown that provided the fiber length between the sensing tip and receiver is less that 2 m that interference due to Rayleigh backscatter will not comprise operation of the refractometer. A novel coupler based on a hybrid silica fiber-plastic fiber design is used experimentally to provide a comparison to the modelled results. It is shown that the high directivity (>35 dB) of this coupler can significantly enhance the resolution of the refractometer.

  12. A 2×2 SOI mach-zehnder thermo-optical switch based on strongly guided paired multimode interference couplers

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A silicon-on-insulator 2×2 Mach-Zehnder thermo-optical switch is developed based on strongly guided paired multimode interference couplers. The multimode-interference couplers were etched deeply for improving coupler characteristics such as self-imaging quality, uniformity and fabrication tolerance. The proposed switch achieves good performances, including a low insertion loss of -11 .OdB, a fiber-waveguide coupling loss of -4.3dB and a fast response speed measured to be 3.5 and 8.8 μs for raise and fall switching time, respectively.

  13. A Simulation Tool for Steady State Thermal Performance Applied to the SPL Double-Walled Tube RF Power Coupler

    CERN Document Server

    Bonomi, R

    2014-01-01

    This note reports on the study carried out to design a tool for steady-state thermal performance of the RF power coupler inside the SPL cryostat. To reduce the amount of heat penetrating into the helium bath where the cavity is placed, the main coupler is actively cooled by means of an adequate flow rate of helium gas. The knowledge of the temperature profiles and the overall thermal performance of the power coupler are fundamental for the estimation of the total heat load budget of the cryostat.

  14. Thermomechanical analysis of a composite grating

    Energy Technology Data Exchange (ETDEWEB)

    Cid, Jose [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas; Araujo, Marcia [PETROBRAS, Rio de Janeiro, RJ (Brazil); DeJoode, Alex; Abd, Imad [Reverse Engineering Ltd, Didsbury, Manchester (United Kingdom)

    2000-07-01

    The aim of the work carried out was to assess the structural performance of polymer composite gratings during a fire. The gratings are made from Fibre Reinforced Plastic (GRP) and are proposed for use as walkways on offshore platforms. During a fire, the gratings are subjected to high temperatures which reduce their structural performance. A numerical model based on experimental results, as well as data published in the literature was developed. The investigation focused on assessing the grating load capacity to carry a fire-fighter and fire-fighting equipment during a fire situation. It was assumed that 120 deg C would be the highest practical temperature for a fire-fighter to attack a fire. Subsequently, the grating performance was investigated for a range of temperatures from ambient to 120 deg C with the temperatures 60, 90 and 120 deg C representing the key targets for lower middle and upper limits. The requirements to assess the mechanical performance of the grating at the local level and global levels necessitated the need to develop a numerical technique to enhance the conventional functionality of the finite element code. The developed material model and the associated numerical technique produced a sophisticated numerical tool capable of assessing the structural response of the gratings at elevated temperatures up to 120 deg C. The comparison between the numerical results and the measured data illustrates robustness of the developed numerical tools, although certain predictions showed relatively poorer agreement than anticipated. (author)

  15. Planar double-grating microspectrometer.

    Science.gov (United States)

    Grabarnik, Semen; Wolffenbuttel, Reinoud; Emadi, Arwin; Loktev, Mikhail; Sokolova, Elena; Vdovin, Gleb

    2007-03-19

    We report on a miniature spectrometer with a volume of 0.135 cm(3) and dimensions of 3x3x11 mm, mounted directly on the surface of a CCD sensor. The spectrometer is formed by two flat diffraction gratings that are designed to perform both the dispersion and imaging functions, eliminating the need for any spherical optics. Two separate parts of the device were fabricated with the single-mask 1 mum lithography on a single glass wafer. The wafer was diced and the device was assembled and directly mounted onto a CCD sensor. The resolution of 3 nm, spectral range of 450 to 750 nm and the optical throughput of ~9% were measured to be in a complete agreement with the model used for the development of the device.

  16. A Novel Method for Heightening Sensitivity of Prism Coupler-Based SPR Sensor

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhi-Wei; WEN Ting-Dun; WU Zhi-Fang

    2011-01-01

    We present a novel method for heightening the sensitivity of a prism coupler-based surface plasmon resonance (SPR) sensor. The method is based on the total reflection prism made of BK7 glass combined with the Kretschmann geometry of theattenuated total reflection (ATR) method. Compared to the conventional methods of prism coupler-based SPR the novel method provides higher semsitivity to the measurement system.Theoretical simulations show that the detetion sensitivity to the refractive index (RI) of the sensor based on the novel approach has a strong dependence on the thickness of the metal layer. The RI resolution of the sensor is predicted to be 8 × 107 refractive indox units (RIU) under the condition of optimum metal film thickness.This novel method can leave out a precision angle rotation device in the angle modulation and it is unnecessary to adjust the acceptance angle of the light detector. The principal advantage of this method over other methods of light intensity modulation based on prism coupler-based SPR is high sensitivity, expediency to measure and aplication of long distances.%@@ We present a novel method for heightening the sensitivity of a prism coupler-based surface plasmon resonance(SPR) sensor.The method is based on the total reflection prism made of BK7 glass combined with the Kretschmann geometry of theattenuated total reflection(ATR) method.Compared to the conventional methods of prism coupler-based SPR,the novel method provides higher sensitivity to the measurement system.Theoretical simulations show that the detection sensitivity to the refractive index(RI) of the sensor based on the novel approach has a strong dependence on the thickness of the metal layer.The RI resolution of the sensor is predicted to be 8 × 10-7 refractive index units(RIU) under the condition of optimum metal film thickness.This novel method can leave out a precision angle rotation device in the angle modulation and it is unnecessary to adjust the acceptance angle of

  17. 21 CFR 133.147 - Grated American cheese food.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Grated American cheese food. 133.147 Section 133... Cheese and Related Products § 133.147 Grated American cheese food. (a)(1) Grated American cheese food is... granular mixture. (2) Grated American cheese food contains not less than 23 percent of milkfat,...

  18. An all fiber apparatus for microparticles selective manipulation based on a variable ratio coupler and a microfiber

    Science.gov (United States)

    Li, Baoli; Luo, Wei; Xu, Fei; Lu, Yanqing

    2016-09-01

    We propose an all fiber apparatus based on a variable ratio coupler which can transport microparticles controllably and trap particles one by one along a microfiber. By connecting two output ports of a variable ratio coupler with two end pigtails of a microfiber and launching a 980 nm laser into the variable ratio coupler, particles in suspension were trapped to the waist of microfiber due to a gradient force and then transported along the microfiber due to a total scattering force generated by two counter-propagating beams. The direction of transportation was controlled by altering the coupling ratio of the variable ratio coupler. When the intensities of two output ports were equivalent, trapped particles stayed at fixed positions. With time going, another particle around the micro fiber was trapped onto the microfiber. There were three particles trapped in total in our experiment. This technique combines with the function of conventional tweezers and optical conveyor.

  19. Large size metallic glass gratings by embossing

    Science.gov (United States)

    Ma, J.; Yi, J.; Zhao, D. Q.; Pan, M. X.; Wang, W. H.

    2012-09-01

    Bulk metallic glasses have excellent thermoforming ability in their wide supercooled liquid region. We show that large-size metallic glass grating (˜8 × 8 mm2) with fine periodicity and ultra smooth surface feature can be readily fabricated by hot embossing. The method for fabrication of gratings is proved to be much cheaper, and requires low pressure and short time (less than 30 s). The metallic glass gratings exhibit comparable optical properties such as rainbow-like spectrum when shone by fluorescent lamp light.

  20. Fiber Bragg Grating Sensors for Harsh Environments

    Directory of Open Access Journals (Sweden)

    Stephen J. Mihailov

    2012-02-01

    Full Text Available Because of their small size, passive nature, immunity to electromagnetic interference, and capability to directly measure physical parameters such as temperature and strain, fiber Bragg grating sensors have developed beyond a laboratory curiosity and are becoming a mainstream sensing technology. Recently, high temperature stable gratings based on regeneration techniques and femtosecond infrared laser processing have shown promise for use in extreme environments such as high temperature, pressure or ionizing radiation. Such gratings are ideally suited for energy production applications where there is a requirement for advanced energy system instrumentation and controls that are operable in harsh environments. This paper will present a review of some of the more recent developments.

  1. Advanced experimental applications for x-ray transmission gratings Spectroscopy using a novel grating fabrication method

    CERN Document Server

    Hurvitz, G; Strum, G; Shpilman, Z; Levy, I; Fraenkel, M

    2012-01-01

    A novel fabrication method for soft x-ray transmission grating and other optical elements is presented. The method uses Focused-Ion-Beam (FIB) technology to fabricate high-quality free standing grating bars on Transmission Electron Microscopy grids (TEM-grid). High quality transmission gratings are obtained with superb accuracy and versatility. Using these gratings and back-illuminated CCD camera, absolutely calibrated x-ray spectra can be acquired for soft x-ray source diagnostics in the 100-3000 eV spectral range. Double grating combinations of identical or different parameters are easily fabricated, allowing advanced one-shot application of transmission grating spectroscopy. These applications include spectroscopy with different spectral resolutions, bandwidths, dynamic ranges, and may serve for identification of high-order contribution, and spectral calibrations of various x-ray optical elements.

  2. Influence of grating thickness in low-contrast subwavelength grating concentrating lenses

    Science.gov (United States)

    Ye, Mao; Yi, Ya Sha

    2016-07-01

    Conventional subwavelength grating concentrating lenses are designed based on calculated phase overlap, wherein the phase change is fixed by the grating thickness, bar-width, and airgap, and therefore the focus. We found that certain concentration effects can still be maintained by changing the grating thickness with the same bar-widths and airgap dimensions. Following that, we discovered the existence of the grating thickness threshold; light concentration intensity spikes upon exceeding this limit. However, the light concentration property does not change continuously with respect to a steady increase in grating thickness. This observation indicates that there exists a concentration mode self-interference effect along the light propagation direction inside the gratings. Our results may provide guidance in designing and fabricating microlenses in a potentially more easy and controllable manner. Such approaches can be utilized in various integrated nanophotonics applications ranging from optical cavities and read/write heads to concentrating photovoltaics.

  3. Long period fiber gratings induced by mechanical resonance

    CERN Document Server

    Shahal, Shir; Duadi, Hamootal; Fridman, Moti

    2015-01-01

    We present a simple, and robust method for writing long period fiber gratings with low polarization dependent losses. Our method is based on utilizing mechanical vibrations of the tapered fiber while pooling it. Our method enables real-time tunability of the periodicity, efficiency and length of the grating. We also demonstrate complex grating by writing multiple gratings simultaneously. Finally, we utilized the formation of the gratings in different fiber diameters to investigate the Young's modulus of the fiber.

  4. Access Platforms for Offshore Wind Turbines Using Gratings

    DEFF Research Database (Denmark)

    Andersen, Thomas Lykke; Rasmussen, Michael R.

    2008-01-01

    The paper deals with forces generated by a stationary jet on different types of gratings and a solid plate. The force reduction factors for the different gratings compared to the solid plate mainly depend on the porosity of the gratings, but the geometry of the grating is also of some importance........ The derived reduction factors are expected to be applicable to design of offshore wind turbine access platforms with gratings where slamming also is an important factor....

  5. Design and Analysis of an Optical Coupler for Concentrated Solar Light Using Optical Fibers in Residential Buildings

    Directory of Open Access Journals (Sweden)

    Afshin Aslian

    2016-01-01

    Full Text Available Concentrated sunlight that is transmitted by fiber optics has been used for generating electricity, heat, and daylight. On the other hand, multijunction photovoltaic cells provide high efficiency for generating electricity from highly concentrated sunlight. This study deals with designing and simulating a high-efficiency coupler, employing a mathematical model to connect sunlight with fiber optics for multiple applications. The coupler concentrates and distributes irradiated light from a primary concentrator. In this study, a parabolic dish was used as the primary concentrator, a coupler that contains nine components called a compound truncated pyramid and a cone (CTPC, all of which were mounted on a plate. The material of both the CTPC and the plate was BK7 optical glass. Fiber optics cables and multijunction photovoltaic cells were connected to the cylindrical part of the CTPC. The fibers would transmit the light to the building to provide heat and daylight, whereas multijunction photovoltaic cells generate electricity. Theoretical and simulation results showed high performance of the designed coupler. The efficiency of the coupler was as high as 92%, whereas the rim angle of the dish increased to an optimum angle. Distributed sunlight in the coupler increased the flexibility and simplicity of the design, resulting in a system that provided concentrated electricity, heat, and lighting for residential buildings.

  6. Directional multimode coupler for planar magnonics: Side-coupled magnetic stripes

    Energy Technology Data Exchange (ETDEWEB)

    Sadovnikov, A. V., E-mail: sadovnikovav@gmail.com; Nikitov, S. A. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation); Kotel' nikov Institute of Radioengineering and Electronics, Russian Academy of Sciences, Moscow 125009 (Russian Federation); Beginin, E. N.; Sheshukova, S. E.; Romanenko, D. V.; Sharaevskii, Yu. P. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation)

    2015-11-16

    We experimentally demonstrate spin waves coupling in two laterally adjacent magnetic stripes. By the means of Brillouin light scattering spectroscopy, we show that the coupling efficiency depends both on the magnonic waveguides' geometry and the characteristics of spin-wave modes. In particular, the lateral confinement of coupled yttrium-iron-garnet stripes enables the possibility of control over the spin-wave propagation characteristics. Numerical simulations (in time domain and frequency domain) reveal the nature of intermodal coupling between two magnonic stripes. The proposed topology of multimode magnonic coupler can be utilized as a building block for fabrication of integrated parallel functional and logic devices such as the frequency selective directional coupler or tunable splitter, enabling a number of potential applications for planar magnonics.

  7. A Ratiometric Wavelength Measurement Based on a Silicon-on-Insulator Directional Coupler Integrated Device

    Directory of Open Access Journals (Sweden)

    Pengfei Wang

    2015-08-01

    Full Text Available A ratiometric wavelength measurement based on a Silicon-on-Insulator (SOI integrated device is proposed and designed, which consists of directional couplers acting as two edge filters with opposite spectral responses. The optimal separation distance between two parallel silicon waveguides and the interaction length of the directional coupler are designed to meet the desired spectral response by using local supermodes. The wavelength discrimination ability of the designed ratiometric structure is demonstrated by a beam propagation method numerically and then is verified experimentally. The experimental results have shown a general agreement with the theoretical models. The ratiometric wavelength system demonstrates a resolution of better than 50 pm at a wavelength around 1550 nm with ease of assembly and calibration.

  8. Multiwavelength mode-locked cylindrical vector beam fiber laser based on mode selective coupler

    Science.gov (United States)

    Huang, Ping; Cai, Yu; Wang, Jie; Wan, Hongdan; Zhang, Zuxing; Zhang, Lin

    2017-10-01

    We propose and demonstrate a multiwavelength mode-locked fiber laser with cylindrical vector beam generation for the first time, to the best of our knowledge. The mode-locking mechanism is based on a nonlinear polarization rotation effect in fiber, and the multiwavelength operation is contributed to by an in-line birefringence fiber filter with periodic multiple passbands, formed by incorporating a section of polarization maintaining fiber into the laser cavity with a fiber polarizer. Furthermore, by using a home-made mode selective coupler, which acts as both a mode converter from fundamental mode to higher-order mode and an output coupler, multiwavelength mode-locked cylindrical vector beams have been obtained. This may have potential applications in mode-division multiplexing optical fiber communication and material processing.

  9. Research of new packaging and cooling technique for high power fiber laser used pump coupler

    Science.gov (United States)

    Mu, Wei; Si, Xu; Lin, Ya-jun; Xu, Cheng-lin; Ma, Yun-liang; Xiao, Chun

    2015-10-01

    This article analyzes the advantages and disadvantages of a packaging structure for pump coupler, where common heat conduction material is used. In this study, the possibility of using new technology of thermal conductivity is discussed. We also proposes a solution that make the function and effect of package more uniform. A serial of experiments are done for research the cooling effect and the working reliability of the fiber combiners and couplers. Experiment proves that after improved method of package, the cooling speed increases significantly comparing the sample with old type of package technique. The technique discussed in this paper will make the high power fiber laser working long time with steady power output and high efficiency.

  10. Broadband directional couplers fabricated in bulk glass with high repetition rate femtosecond laser pulses.

    Science.gov (United States)

    Chen, Wei-Jen; Eaton, Shane M; Zhang, Haibin; Herman, Peter R

    2008-07-21

    A femtosecond fiber laser was applied to fabricate broadband directional couplers inside bulk glass for general power splitting application in the 1250 to 1650-nm wavelength telecom spectrum. The broadband response was optimized over the 400-nm bandwidth by tailoring the coupling strength and the waveguide interaction length to balance the differing wavelength dependence of the straight interaction and bent transition regions. High spatial finesse of the femtosecond-laser writing technique enabled close placement (approxiamtely 6 microm) of adjacent waveguides that underpinned the wavelength-flattened broadband response at any coupling ratio in the 0% to 100% range. The spectral responses were well-represented by coupled mode theory, permitting simple design and implementation of broadband couplers for bulk 3D optical circuit integration.

  11. Demonstration of a Tuneable Coupler for Superconducting Qubits Using Coherent, Time Domain, Two-Qubit Operations

    CERN Document Server

    Bialczak, R C; Hofheinz, M; Lenander, M; Lucero, E; Neeley, M; O'Connell, A D; Sank, D; Wang, H; Weides, M; Wenner, J; Yamamoto, T; Cleland, A N; Martinis, J M

    2010-01-01

    A major challenge in the field of quantum computing is the construction of scalable qubit coupling architectures. Here, we demonstrate a novel tuneable coupling circuit that allows superconducting qubits to be coupled over long distances. We show that the inter-qubit coupling strength can be arbitrarily tuned over nanosecond timescales within a sequence that mimics actual use in an algorithm. The coupler has a measured on/off ratio of 1000. The design is self-contained and physically separate from the qubits, allowing the coupler to be used as a module to connect a variety of elements such as qubits, resonators, amplifiers, and readout circuitry over long distances. Such design flexibility is likely to be essential for a scalable quantum computer.

  12. Design of a compact polarization beam splitter based on a deformed photonic crystal directional coupler

    Institute of Scientific and Technical Information of China (English)

    Ren Cang; Zheng Wan-Hua; Wang Ke; Du Xiao-Yu; Xing Ming-Xin; Chen Liang-Hui

    2008-01-01

    In this paper a compact polarization beam splitter based on a deformed photonic crystal directional coupler is designed and simulated. The transverse-electric (TE) guided mode and transverse-magnetic (TM) guided mode are split due to different guiding mechanisms. The effect of the shape deformation of the air holes on the coupler is studied. It discovered that the coupling strength of the coupled wavegnides is strongly enhanced by introducing elliptical airholes, which reduce the device length to less than 18.5μm. A finite-difference time-domain simulation is performed to evaluate the performance of the device, and the extinction ratios for both TE and TM polarized light are higher than 20 dB.

  13. Design of N-type feedthrough for HOM coupler for cERL injector cavity

    Science.gov (United States)

    Watanabe, K.; Noguchi, S.; Kako, E.; Shishido, T.

    2014-01-01

    The injector cryomodule for the compact energy recovery linac (cERL) is under development at KEK. The cryomodule with 3L-band 2-cell cavities was built in June 2012. A prototype 2-cell cavity and three other 2-cell cavities with five higher-order-mode (HOM) couplers for actual operation were fabricated in May 2011. The vertical tests of these cavities were carried out after standard surface preparation at the KEK Superconducting accelerator Test Facility (KEK-STF) from October 2010 to March 2012. Radio-frequency feedthroughs with high thermal conductivity for the HOM coupler were also developed to achieve 12.5 MV/m CW operation in the cryomodule. A Kyocera NR-type connector was modified to connect to this target. The results of vertical tests of the 2-cell cavities to measure their feedthrough performance will be reported in this paper.

  14. Eddy current loss calculation and thermal analysis of axial-flux permanent magnet couplers

    Directory of Open Access Journals (Sweden)

    Di Zheng

    2017-02-01

    Full Text Available A three-dimensional magnetic field analytical model of axial-flux permanent magnet couplers is presented to calculate the eddy current loss, and the prediction of the copper plate temperature under various loads is analyzed. The magnetic field distribution is calculated, and then the eddy current loss is obtained, with the magnetic field analytical model established in cylindrical coordinate. The influence of various loads on eddy current loss is analyzed. Furthermore, a thermal model of axial-flux permanent magnet couplers is established by taking the eddy current loss as the heat source, using the electromagnetic-thermal coupled method. With the help of the thermal model, the influence of various loads on copper plate temperature rise is also analyzed. The calculated results are compared with the results of finite element method and measurement. The comparison results confirm the validity of the magnetic field analytical model and thermal model.

  15. Bi-directional triplexer with butterfly MMI coupler using SU-8 polymer waveguides

    Science.gov (United States)

    Mareš, David; Jeřábek, Vítězslav; Prajzler, Václav

    2015-01-01

    We report about a design of a bi-directional planar optical multiplex/demultiplex filter (triplexer) for the optical part of planar hybrid WDM bi-directional transceiver in fiber-to-the-home (FTTH) PON applications. The triplex lightwave circuit is based on the Epoxy Novolak Resin SU-8 waveguides on the silica-on-silicon substrate with Polymethylmethacrylate cladding layer. The triplexer is comprised of a linear butterfly concept of multimode interference (MMI) coupler separating downstream optical signals of 1490 nm and 1550 nm. For the upstream channel of 1310 nm, an additional directional coupler (DC) is used to add optical signal of 1310 nm propagating in opposite direction. The optical triplexer was designed and optimized using beam propagation method. The insertion losses, crosstalk attenuation, and extinction ratio for all three inputs/outputs were investigated. The intended triplexer was designed using the parameters of the separated DC and MMI filter to approximate the idealized direct connection of both devices.

  16. New design of a triplexer using ring resonator integrated with directional coupler based on photonic crystals

    Science.gov (United States)

    Wu, Yaw-Dong; Shih, Tien-Tsorng; Lee, Jian-Jang

    2009-11-01

    In this paper, we proposed the design of directional coupler integrated with ring resonator based on two-dimensional photonic crystals (2D PCs) to develop a triplexer filter. It can be widely used as the fiber access network element for multiplexer-demultiplexer wavelength selective in fiber-to-the-home (FTTH) communication systems. The directional coupler is chosen to separate the wavelengths of 1490nm and 1310nm. The ring resonator separates the wavelength of 1550nm. The transmission efficiency is larger than 90%. Besides, the total size of propose triplexer is only 19μm×12μm. We present simulation results using the finite-difference time-domain (FDTD) method for the proposed structure.

  17. Liquid crystal on subwavelength metal gratings

    Energy Technology Data Exchange (ETDEWEB)

    Palto, S. P.; Barnik, M. I.; Artemov, V. V.; Shtykov, N. M.; Geivandov, A. R.; Yudin, S. G.; Gorkunov, M. V. [Shubnikov Institute of Crystallography of Russian Academy of Sciences, Leninsky pr. 59, 119333 Moscow (Russian Federation)

    2015-06-14

    Optical and electrooptical properties of a system consisting of subwavelength metal gratings and nematic liquid crystal layer are studied. Aluminium gratings that also act as interdigitated electrodes are produced by focused ion beam lithography. It is found that a liquid crystal layer strongly influences both the resonance and light polarization properties characteristic of the gratings. Enhanced transmittance is observed not only for the TM-polarized light in the near infrared spectral range but also for the TE-polarized light in the visible range. Although the electrodes are separated by nanosized slits, and the electric field is strongly localized near the surface, a pronounced electrooptical effect is registered. The effect is explained in terms of local reorientation of liquid crystal molecules at the grating surface and propagation of the orientational deformation from the surface into the bulk of the liquid crystal layer.

  18. Theory of photorefractive dynamic grating formulation

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The photorefractive holographic recording and two-beam coupling are both dynamic grating formulation process. The interference light intensity of the two coherent beams induces a phase grating though photo-induced refractive index variation and the phase grating changing the intensities of the two beams through beam-coupling take place at the same time. By solving simultaneously the band transport equations and wave-coupled equations, and using the light intensity modulation as the main variable, the analytic solution is obtained, which is valid for any light intensity modulation and constant light excitation efficiency. Here all the mechanics of drift, diffusion and photovoltaic effect are considered. The result shows that the modulation of the dynamic grating varies more slowly compared with that of the linear modulation approximation.

  19. Hydraulic Capacity of an ADA Compliant Street Drain Grate

    Energy Technology Data Exchange (ETDEWEB)

    Lottes, Steven A. [Argonne National Lab. (ANL), Argonne, IL (United States); Bojanowski, Cezary [Argonne National Lab. (ANL), Argonne, IL (United States)

    2015-09-01

    Resurfacing of urban roads with concurrent repairs and replacement of sections of curb and sidewalk may require pedestrian ramps that are compliant with the American Disabilities Act (ADA), and when street drains are in close proximity to the walkway, ADA compliant street grates may also be required. The Minnesota Department of Transportation ADA Operations Unit identified a foundry with an available grate that meets ADA requirements. Argonne National Laboratory’s Transportation Research and Analysis Computing Center used full scale three dimensional computational fluid dynamics to determine the performance of the ADA compliant grate and compared it to that of a standard vane grate. Analysis of a parametric set of cases was carried out, including variation in longitudinal, gutter, and cross street slopes and the water spread from the curb. The performance of the grates was characterized by the fraction of the total volume flow approaching the grate from the upstream that was captured by the grate and diverted into the catch basin. The fraction of the total flow entering over the grate from the side and the fraction of flow directly over a grate diverted into the catch basin were also quantities of interest that aid in understanding the differences in performance of the grates. The ADA compliant grate performance lagged that of the vane grate, increasingly so as upstream Reynolds number increased. The major factor leading to the performance difference between the two grates was the fraction of flow directly over the grates that is captured by the grates.

  20. In-situ Blast Testing of Shear-Screw Mechanical Couplers

    Science.gov (United States)

    2010-07-01

    of installation and availability. There are multiple suppliers of shear screw couplers; for this study, the Double Barrel Zap Screwlok system by...Barsplice Products Inc. was selected. The Double Barrel Zap Screwlok is capable of developing 125 percent of the yield strength of a No. 5 bar and has...additional mechanical resistance, via dowel action. A photograph of the Double Barrel Zap Screwlok couple is provided in Figure 1 . For the

  1. Influence of group—velocity mismatch on soliton switching in a nonlinear fibre coupler

    Institute of Scientific and Technical Information of China (English)

    LiHong; HuangDe-Xiu; WangDong-Ning

    2003-01-01

    In this work, the influence of group-velocity mismatch on soliton self-routing pulse switching in a nonlinear fibre coupler is discussed in detail by the use of both variational approach and numerical simulation. The results obtained show that the group-velocity mismatch leads to the relative displacement between the two orthogonal polarization modes, increase of the critical power, and reduction of the elimination-light ratio. For sub-ps pulse, the influence cannot be neglected.

  2. A Case of the Vibrant Soundbridge Stapes Coupler in Patients with Mixed Hearing Loss

    OpenAIRE

    Park, Ah Young; Jeon, Ju Hyun; Moon, In Seok; Choi, Jae Young

    2014-01-01

    The Vibrant Soundbridge (VSB) with stapes clip coupler placement at the stapes head has been used successfully to treat mixed hearing loss. Coupling between the floating mass transducer of the VSB and the stapes head is technically less demanding than incus vibroplasty and is more likely to generate a positive outcome without significantly changing residual hearing or resulting in medical or surgical complications. A 65-year-old man with bilateral mixed hearing loss and chronic otitis media u...

  3. Ultralow loss, high Q, four port resonant couplers for quantum optics and photonics.

    Science.gov (United States)

    Rokhsari, H; Vahala, K J

    2004-06-25

    We demonstrate a low-loss, optical four port resonant coupler (add-drop geometry), using ultrahigh Q (>10(8)) toroidal microcavities. Different regimes of operation are investigated by variation of coupling between resonator and fiber taper waveguides. As a result, waveguide-to-waveguide power transfer efficiency of 93% (0.3 dB loss) and nonresonant insertion loss of 0.02% (photonic networks.

  4. Coupling analysis at the coupler and edge-coupled unilateral fin line

    Science.gov (United States)

    Fernandes, Humberto C. C.; Silva, Sidney A.; Silva, Jose P.

    1998-11-01

    Computer programs are developed in FORTRAN 77 and Matlab for Windows languages, given the results in 3-D of the dispersion and of the coupling, as functions of the frequency, conductivity and permittivity for the unilateral fin lines coupler asymmetric in E-plane, on semiconductor substrate. The characteristic impedance and complex propagation constant, for the odd and even-modes excitation are obtained by Transverse Transmission Line method -- TTL. These programs are easily used in graduate and undergraduate courses with good efficiency.

  5. Spatial heterodyne interferometry with polarization gratings.

    Science.gov (United States)

    Kudenov, Michael W; Miskiewicz, Matthew N; Escuti, Michael J; Dereniak, Eustace L

    2012-11-01

    The implementation of a polarization-based spatial heterodyne interferometer (SHI) is described. While a conventional SHI uses a Michelson interferometer and diffraction gratings, our SHI exploits mechanically robust Wollaston prisms and polarization gratings. A theoretical model for the polarization SHI is provided and validated with data from our proof of concept experiments. This device is expected to provide a compact monolithic sensor for subangstrom resolution spectroscopy in remote sensing, biomedical imaging, and machine vision applications.

  6. Sampled phase-shift fiber Bragg gratings

    Institute of Scientific and Technical Information of China (English)

    Xu Wang(王旭); Chongxiu Yu(余重秀); Zhihui Yu(于志辉); Qiang Wu(吴强)

    2004-01-01

    A phase-shift fiber Bragg grating (FBG) with sampling is proposed to generate a multi-channel bandpass filter in the background of multi-channel stopbands. The sampled noire fiber gratings are analyzed by Fourier transform theory first, and then simulation and experiment are performed, the results show that transmission peaks are opened in every reflective channel, the spectrum shape of every channel is identical.It can be used to fabricate multi-wavelength distributed feedback (DFB) fiber laser.

  7. Straightforward and accurate technique for post-coupler stabilization in drift tube linac structures

    Science.gov (United States)

    Khalvati, Mohammad Reza; Ramberger, Suitbert

    2016-04-01

    The axial electric field of Alvarez drift tube linacs (DTLs) is known to be susceptible to variations due to static and dynamic effects like manufacturing tolerances and beam loading. Post-couplers are used to stabilize the accelerating fields of DTLs against tuning errors. Tilt sensitivity and its slope have been introduced as measures for the stability right from the invention of post-couplers but since then the actual stabilization has mostly been done by tedious iteration. In the present article, the local tilt-sensitivity slope TSn' is established as the principal measure for stabilization instead of tilt sensitivity or some visual slope, and its significance is developed on the basis of an equivalent-circuit diagram of the DTL. Experimental and 3D simulation results are used to analyze its behavior and to define a technique for stabilization that allows finding the best post-coupler settings with just four tilt-sensitivity measurements. CERN's Linac4 DTL Tank 2 and Tank 3 have been stabilized successfully using this technique. The final tilt-sensitivity error has been reduced from ±100 %/MHz down to ±3 %/MHz for Tank 2 and down to ±1 %/MHz for Tank 3. Finally, an accurate procedure for tuning the structure using slug tuners is discussed.

  8. RF Couplers for Normal-Conducting Photoinjector of High-Power CW FEL

    CERN Document Server

    Kurennoy, Sergey; Wood, Richard L; Schultheiss, T J; Rathke, John; Young, Lloyd

    2004-01-01

    A high-current emittance-compensated RF photoinjector is a key enabling technology for a high-power CW FEL. A preliminary design of a normal-conducting, 2.5-cell pi-mode, 700-MHz CW RF photoinjector that will be built for demonstration purposes, is completed. This photoinjector will be capable of accelerating a 100-mA electron beam (3 nC per bunch at 35 MHz bunch repetition rate) to 2.7 MeV while providing an emittance below 7 mm-mrad at the wiggler. More than 1 MW of RF power will be fed into the photoinjector cavity through two ridge-loaded tapered waveguides. The waveguides are coupled to the cavity by "dog-bone" irises cut in a thick wall. Due to CW operation of the photoinjector, the cooling of the coupler irises is a rather challenging thermal management project. This paper presents results of a detailed electromagnetic modeling of the coupler-cavity system, which has been performed to select the coupler design that minimizes the iris heating due to RF power loss in its walls.

  9. RF Couplers for Normal-Conducting Photoinjector of High-Power CW FEL

    Science.gov (United States)

    Kurennoy, Sergey; Schrage, Dale; Wood, Richard; Schultheiss, Tom; Rathke, John; Young, Lloyd

    2004-05-01

    A high-current emittance-compensated RF photoinjector is a key enabling technology for a high-power CW FEL. A preliminary design of a normal-conducting, 2.5-cell pi-mode, 700-MHz CW RF photoinjector that will be build for demonstration purposes, is completed. This photoinjector will be capable of accelerating a 100-mA electron beam (3 nC per bunch at 35 MHz bunch repetition rate) to 2.7 MeV while providing an emittance below 7 mm-mrad at the wiggler. More than 1 MW of RF power will be fed into the photoinjector cavity through two ridge-loaded tapered waveguides. The waveguides are coupled to the cavity by "dog-bone" irises cut in a thick wall. Due to CW operation of the photoinjector, the cooling of the coupler irises is a rather challenging thermal management project. This paper presents results of a detailed electromagnetic modeling of the coupler-cavity system, which has been performed to select the coupler design that minimizes the iris heating due to RF power loss in its walls.

  10. RF couplers for normal-conducting photoinjector of high-power CW FEL

    Energy Technology Data Exchange (ETDEWEB)

    Kurennoy, S. (Sergey)

    2004-01-01

    A high-current emittance-compensated RF photoinjector is a key enabling technology for a high-power CW FEL. A preliminary design of a normal-conducting, 2.5-cell pi-mode, 700-MHz CW RF photoinjector that will be built for demonstration purposes, is completed. This photoinjector will be capable of accelerating a 100-mA electron beam (3 nC per bunch at 35 MHz bunch repetition rate) to 2.7 MeV while providing an emittance below 7 mm-mrad at the wiggler. More than 1 MW of RF power will be fed into the photoinjector cavity through two ridge-loaded tapered waveguides. The waveguides are coupled to the cavity by 'dog-bone' irises cut in a thick wall. Due to CW operation of the photoinjector, the cooling of the coupler irises is a rather challenging thermal management project. This paper presents results of a detailed electromagnetic modeling of the coupler-cavity system, which has been performed to select the coupler design that minimizes the iris heating due to RF power loss in its walls.

  11. Detection of recombinant growth hormone by evanescent cascaded waveguide coupler on silica-on-silicon.

    Science.gov (United States)

    Ozhikandathil, Jayan; Packirisamy, Muthukumaran

    2013-05-01

    An evanescent wave based biosensor is developed on the silica-on-silicon (SOS) with a cascaded waveguide coupler for the detection of recombinant growth hormone. So far, U -bends and tapered waveguides are demonstrated for increasing the penetration depth and enhancing sensitivity of the evanescent wave sensor. In this work, a monolithically integrated sensor platform containing a cascaded waveguide coupler with optical power splitters and combiners designed with S -bends and tapper waveguides is demonstrated for an enhanced detection of recombinant growth hormone. In the cascaded waveguide coupler, a large surface area to bind the antibody with increased penetration depth of evanescent wave to excite the tagged-rbST is obtained by splitting the waveguide into multiple paths using Y splitters designed with s -bends and subsequently combining them back to a single waveguide through tapered waveguide and combiners. Hence a highly sensitive fluoroimmunoassay sensor is realized. Using the 2D FDTD (Finite-difference time-domain method) simulation of waveguide with a point source in Rsoft FullWAVE, the fluorescence coupling efficiency of straight and bend section of waveguide is analyzed. The sensor is demonstrated for the detection of fluorescently-tagged recombinant growth hormone with the detection limit as low as 25 ng/ml.

  12. Comparison of coaxial higher order mode couplers for the CERN Superconducting Proton Linac study

    Directory of Open Access Journals (Sweden)

    K. Papke

    2017-06-01

    Full Text Available Higher order modes (HOMs may affect beam stability and refrigeration requirements of superconducting proton linacs such as the Superconducting Proton Linac, which is studied at CERN. Under certain conditions beam-induced HOMs can accumulate sufficient energy to destabilize the beam or quench the superconducting cavities. In order to limit these effects, CERN considers the use of coaxial HOM couplers on the cutoff tubes of the 5-cell superconducting cavities. These couplers consist of resonant antennas shaped as loops or probes, which are designed to couple to potentially dangerous modes while sufficiently rejecting the fundamental mode. In this paper, the design process is presented and a comparison is made between various designs for the high-beta SPL cavities, which operate at 704.4 MHz. The rf and thermal behavior as well as mechanical aspects are discussed. In order to verify the designs, a rapid prototype for the favored coupler was fabricated and characterized on a low-power test-stand.

  13. Study on self-imaging properties for line-tapered multimode interference couplers

    Science.gov (United States)

    Le, ZiChun; Huang, SunGang; Fu, MingLei; Dong, Wen; Zhang, Jie; Zhang, Ming

    2011-10-01

    The line-tapered multimode interference (MMI) couplers have advantage of compact dimension compared with conventional straight MMI couplers and then are more suitable for integrated optical components. In this paper, the self-imaging properties including general self-image and overlapping-image properties for the line-tapered MMI couplers are discussed thoroughly. Based on the width equation we defined, compact equations for the positions, amplitudes, phases of general images and overlapping images are deduced. Three disciplines for general self-imaging and four disciplines for overlapping-imaging are summarized and discussed. In addition, the overlapping-image properties are further studied by matrix analytic method and an inductive reasoning method of constructing phase and intensity matrix is developed based on it. Finally, all the theoretical results are compared with simulations results obtained by the finite-difference beam propagation method (FD-BPM). Both theoretical and simulation results are shown in this paper and demonstrated to be coincided with each other to a great extent.

  14. Dynamics of higher-order solitons in regular and PT-symmetric nonlinear couplers

    CERN Document Server

    Driben, R

    2012-01-01

    Dynamics of symmetric and antisymmetric 2-solitons and 3-solitons is studied in the model of the nonlinear dual-core coupler and its PT-symmetric version. Regions of the convergence of the injected perturbed symmetric and antisymmetric N-solitons into symmetric and asymmetric quasi-solitons are found. In the PT-symmetric system, with the balanced gain and loss acting in the two cores, borders of the stability against the blowup are identified. Notably, in all the cases the stability regions are larger for antisymmetric 2-soliton inputs than for their symmetric counterparts, on the contrary to previously known results for fundamental solitons (N=1). Dynamical regimes (switching) are also studied for the 2-soliton injected into a single core of the coupler. In particular, a region of splitting of the input into a pair of symmetric solitons is found, which is explained as a manifestation of the resonance between the vibrations of the 2-soliton and oscillations of energy between the two cores in the coupler.

  15. Experimental characteristics of a lower hybrid wave multi-junction coupler in the HT-7 tokamak

    Institute of Scientific and Technical Information of China (English)

    Ding Bo-Jiang; Jiang Min; Zhang Gong-Rang; Huang Feng; Zhao Yan-Ping; Kuang Guang-Li; HT-7 team; Shan Jia-Fang; Liu Fu-Kun; Fang Yu-De; Wei Wei; Wu Zhen-Wei; Chen Zhong-Yong; Xu Han-Dong; Wang Mao

    2006-01-01

    A phase-controlled lower hybrid wave (LHW) multi-junction (M J) coupler (3(rows)×4(columns)×4 (subwaveguides)) has been developed in the HT-7 tokamak. Simulations show that it is more effective for driving plasma current than an ordinary phase-controlled LHW antenna (3(rows)× 12(columns)) (traditional coupler). The plasma-wave coupling experiments show that the reflection coefficient (RC) is below 10%, implying that the MJ grill can launch the wave into the plasma effectively. The effect of power spectrum launched by the MJ coupler on RC indicates that an optimal condition is requisite for a better coupling in the lower hybrid current drive (LHCD) experiments. Studies indicate that the drive efficiency of the MJ antenna is higher than that of the traditional one, which is mainly ascribed to the discrepancy in impurity concentration, plasma temperature, and spectrum directivity. An improved confinement with an electron internal transport barrier is obtained by LHCD. The analysis shows that the modified negative (low)magnetic shear and the change of radial electric field profile due to LHCD are possible factors responsible for the eITB formation.

  16. Arbitrary coupling ratio multimode interference couplers in Silicon-on-Insulator

    CERN Document Server

    Doménech, José David; Gargallo, Bernardo; Muñoz, Pascual

    2014-01-01

    In this paper we present the design, manufacturing, characterization and analysis of the coupling ratio spectral response for Multimode Interference (MMI) couplers in Silicon-on-Insulator (SOI) technology. The couplers were designed using a Si rib waveguide with SiO 2 cladding, on a regular 220 nm film and 2 {\\mu}m buried oxide SOI wafer. A set of eight different designs, three canonical and five using a widened/narrowed coupler body, have been subject of study, with coupling ratios 50:50, 85:15 and 72:28 for the former, and 95:05, 85:15, 75:25, 65:35 and 55:45 for the latter. Two wafers of devices were fabricated, using two different etch depths for the rib waveguides. A set of six dies, three per wafer, whose line metrology matched the design, were retained for characterization. The coupling ratios obtained in the experimental results match, with little deviations, the design targets for a wavelength range between 1525 and 1575 nm, as inferred from spectral measurements and statistical analyses. Excess loss...

  17. Analysis of a Substrate Integrated Waveguide Hybrid Ring (Rat-Race Coupler

    Directory of Open Access Journals (Sweden)

    Ramin Dehdasht-Heydari

    2014-01-01

    Full Text Available This paper presents an efficient analysis of a substrate integrated waveguide (SIW single-layer hybrid ring coupler (rat-race for millimeter-wave and microwave applications. The scattered field from each circular cylinder is expanded by cylindrical eigenfunctions with unknown coefficients that have been solved by electric and magnetic tangential boundary on each metallic via. The coupler S-matrix is calculated by using mode matching that uses the cylindrical vector expansion analysis to minimize the computational time and provides more physical insight. To achieve higher bandwidth, the radiuses of the coupler under analysis have been optimized in Matlab code by invasive weed optimization (IWO method, and the results have been verified by CST package. The return loss and the isolation are less than −15 dB, and −18 dB, respectively. The insertion loss is divided equally -3±0.2 dB, with 0±5 and 180±10 degrees in output ports over the operating frequency bandwidth and the agreement of phase differences in output ports has been examined objectively by feature selective validation (FSV technique.

  18. TTF3 power coupler thermal analysis for LCLS-II CW operation

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, L. [SLAC National Accelerator Lab., Menlo Park, CA (United States). Linac Coherent Light Source (LCLS); Adolphsen, C. [SLAC National Accelerator Lab., Menlo Park, CA (United States). Linac Coherent Light Source (LCLS); Li, Z. [SLAC National Accelerator Lab., Menlo Park, CA (United States). Linac Coherent Light Source (LCLS); Nantista, C. [SLAC National Accelerator Lab., Menlo Park, CA (United States). Linac Coherent Light Source (LCLS); Raubenheimer, T. [SLAC National Accelerator Lab., Menlo Park, CA (United States). Linac Coherent Light Source (LCLS); Solyak, N. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Gonin, I. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2015-05-13

    The TESLA 9-cell SRF cavity design has been adopted for use in the LCLS-II SRF Linac. Its TTF3 coaxial fundamental power coupler (FPC), optimized for pulsed operation in European XFEL and ILC, requires modest changes to make it suitable for LCLS-II continuous-wave (CW) operation. For LCLS-II it must handle up to 7 kW of power, fully reflected, with the maximum temperature around 450 K, the coupler bake temperature. In order to improve TTF3 FPC cooling, an increased copper plating thickness will be used on the inner conductor of the ‘warm’ section of the coupler. Also, the antenna will be shortened to achieve higher cavity Qext values. Fully 3D FPC thermal analysis has been performed using the SLAC-developed parallel finite element code suite ACE3P, which includes electromagnetic codes and an integrated electromagnetic, thermal and mechanical multi-physics code. In this paper, we present TTF3 FPC thermal analysis simulation results obtained using ACE3P as well as a comparison with measurement results.

  19. Waveguide-Type Directional Coupler Based on Substrate Integrated Waveguide (SIW

    Directory of Open Access Journals (Sweden)

    Zohreh Pourgholamhossein

    2012-04-01

    Full Text Available Substrate Integrated Waveguide (SIW is a new type of guided wave structure which could be implemented in both microwave and millimeter wave integrated circuits. In this paper a novel waveguide type directional coupler based on substrate integrated waveguide consisting a double layer dielectric substrate is proposed. The design process is carried out using coupling theory and Chebyshev method. The proposed structure is fully based on SIW structure except at the input-output ports which are microstrip lines. The SIW bends are optimized for the lowest insertion loss using HFSS software. The center frequency of designed 20dB coupler is at 10GHz with 6GHz bandwidth. Based on the simulations the coupling remains almost constant over the coupler bandwidth with less than 2 dB variations. Larger bandwidth can be achieved by increasing the number of apertures. Also if we used a second set of apertures opposite side wall, the coupling would be increased by 6 dB.

  20. Low-loss silicon slot waveguides and couplers fabricated with optical lithography and atomic layer deposition.

    Science.gov (United States)

    Säynätjoki, A; Karvonen, L; Alasaarela, T; Tu, X; Liow, T Y; Hiltunen, M; Tervonen, A; Lo, G Q; Honkanen, S

    2011-12-19

    We demonstrate low-loss silicon slot waveguides patterned with 248 nm deep-UV lithography and filled with atomic layer deposited aluminum oxide. Propagation losses less than 5 dB/cm are achieved with the waveguides. The devices are fabricated using low-temperature CMOS compatible processes. We also demonstrate simple, compact and efficient strip-to-slot waveguide couplers. With a coupler as short as 10 µm, coupling loss is less than 0.15 dB. The low-index and low-nonlinearity filling material allows nonlinearities nearly two orders of magnitude smaller than in silicon waveguides. Therefore, these waveguides are a good candidate for linear photonic devices on the silicon platform, and for distortion-free signal transmission channels between different parts of a silicon all-optical chip. The low-nonlinearity slot waveguides and robust couplers also facilitate a 50-fold local change of the waveguide nonlinearity within the chip by a simple mask design.

  1. DESIGN AND FABRICATION OF 12 GHZ MICROSTRIP DIRECTIONAL COUPLER FOR RF/MICROWAVE APPLICATION

    Directory of Open Access Journals (Sweden)

    AZAHAR FAUZI

    2016-03-01

    Full Text Available Microstrip coupled line is parallel coupled transmission lines formed by coupling two conducting strips (resonator with the same width together at a certain distance. This paper presents the design of microstrip directional coupler without the prior knowledge of the physical geometry. A general configuration directional coupler will be determined by creating a layout in the Agilent Advanced Design System (ADS and momentum. In order to perform simulation, a substrate as well as metallization and mesh should be defined. Hence, the required s-parameter response of the coupler could be obtained. The design will then fabricate on top of RT Duroid 6010 substrate, and finally undergo measuring through Vector Network Analyzer (VNA to evaluate their S-parameter characteristics. Simulated results show insertion loss, isolation, coupling (10.82 dB, and return loss were within the acceptable limits. Directivity of better than 23 dB was achieved in the simulated response. The coupling (9.99 dB of fabricated circuit shows a good agreement with the required specification (10 dB, but the directivity 10.61 dB is quite low in practice. The reason for the discrepancy could, however, due to discontinuities, measuring errors, and fabrication error. However, coupling values show a good agreement between the simulation and measured results.

  2. Suppression of multipacting in high power RF couplers operating with superconducting cavities

    Science.gov (United States)

    Ostroumov, P. N.; Kazakov, S.; Morris, D.; Larter, T.; Plastun, A. S.; Popielarski, J.; Wei, J.; Xu, T.

    2017-06-01

    Capacitive input couplers based on a 50 Ω coaxial transmission line are frequently used to transmit RF power to superconducting (SC) resonators operating in CW mode. It is well known that coaxial transmission lines are prone to multipacting phenomenon in a wide range of RF power level and operating frequency. The Facility for Rare Isotope Beams (FRIB) being constructed at Michigan State University includes two types of quarter wave SC resonators (QWR) operating at 80.5 MHz and two types of half wave SC resonators (HWR) operating at 322 MHz. As was reported in ref. [1] a capacitive input coupler used with HWRs was experiencing strong multipacting that resulted in a long conditioning time prior the cavity testing at design levels of accelerating fields. We have developed an insert into 50 Ω coaxial transmission line that provides opportunity to bias the RF coupler antenna and protect the amplifier from the bias potential in the case of breakdown in DC isolation. Two of such devices have been built and are currently used for the off-line testing of 8 HWRs installed in the cryomodule.

  3. Straightforward and accurate technique for post-coupler stabilization in drift tube linac structures

    CERN Document Server

    Khalvati, Mohammad Reza

    2016-01-01

    The axial electric field of Alvarez drift tube linacs (DTLs) is known to be susceptible to variations due to static and dynamic effects like manufacturing tolerances and beam loading. Post-couplers are used to stabilize the accelerating fields of DTLs against tuning errors. Tilt sensitivity and its slope have been introduced as measures for the stability right from the invention of post-couplers but since then the actual stabilization has mostly been done by tedious iteration. In the present article, the local tilt-sensitivity slope TS 0 n is established as the principal measure for stabilization instead of tilt sensitivity or some visual slope, and its significance is developed on the basis of an equivalent-circuit diagram of the DTL. Experimental and 3D simulation results are used to analyze its behavior and to define a technique for stabilization that allows finding the best post-coupler settings with just four tilt-sensitivity measurements. CERN ’ s Linac4 DTL Tank 2 and Tank 3 have been stabilized succ...

  4. Research on polarization state of prism coupler sensor for measuring liquid refractive index

    Science.gov (United States)

    Zhang, Zhi-Wei

    2013-09-01

    Due to many experimental data required and a lot of calculations involved, it is very complex and cumbersome to model prism-based liquid-refractive-index-measuring methods. By use of the feature of TE-polarized wave and TM-polarized wave and differential measurement principle, we developed a new method of mathematical modeling for measuring refractive index of a liquid based upon Fresnel formula and prism internal reflection at incident angle less than critical angle. With this method only two different concentrations measurements for a kind of solution can lead to the determination of computational model. It introduces the principle of an optic-fiber sensor system based on prism-coupler for measuring refractive index of a liquid, and it contains the configuration picture of the sensing optical path, the spectrogram of the semiconductor laser and the structure block diagram of measuring system, the system is mainly made up of the semiconductor laser with 1654.14nm in wavelength, 1×2 optical switch, Y-shaped photo-coupler with coupled rate 50:50, the detector based on isosceles prism-coupler, the data process and control system based on AT89C51 and photoelectric transformer. For TM-polarized wave and TE-polarized wave, theoretical simulations show that the ratio of sensitivity is 1.11, therefore, the beam that the component of TM-polarized wave is more than the one of TE-polarized wave is advantageous to heightening the systemۥs measurement sensitivity. Measurements are performed to examine the validity of the theoretical model and four theoretical models are given, and these results indicate the feasibility of four theoretical models with an error of 3%. In this study, a beam of light is broken down into two beams in the coupler of Y-shaped coupler, the one acts as the reference optical path, the other is known as the sensing optical path, consequently the method can limit well the fluctuation of the light source, the variation of the photodiodeۥ s dark

  5. A novel single-order diffraction grating: Random position rectangle grating

    Science.gov (United States)

    Zuhua, Yang; Qiangqiang, Zhang; Jing, Wang; Quanping, Fan; Yuwei, Liu; Lai, Wei; Leifeng, Cao

    2016-05-01

    Spectral diagnosis of radiation from laser plasma interaction and monochromation of radiation source are hot and important topics recently. Grating is one of the primary optical elements to do this job. Although easy to fabricate, traditional diffraction grating suffers from multi-order diffraction contamination. On the other hand, sinusoidal amplitude grating has the nonharmonic diffraction property, but it is too difficult to fabricate, especially for x-ray application. A novel nonharmonic diffraction grating named random position rectangle grating (RPRG) is proposed in this paper. Theoretical analysis and experiment results show that the RPRG is both higher order diffraction suppressing and not difficult to fabricate. Additionally, it is highly efficient; its first order absolute theoretical diffraction efficiency reaches 4.1%. Our result shows that RPRG is a novel tool for radiation diagnosis and monochromation. Project supported by the National Natural Science Foundation of China (Grant No. 11375160) and the National Science Instruments Major Project of China (Grant No. 2012YQ130125).

  6. Encoded cell grating array in anti-counterfeit technology

    Institute of Scientific and Technical Information of China (English)

    Zhongyu Chen; N. K. Bao; Po S. Chung

    2005-01-01

    @@ The dot matrix hologram (DMH) has been widely used in anti-counterfeiting label. With the same technology and cell array configuration, we can encode to the incidence beam. These codes can be some image matrix grating with different grating gap and different grating orientation. When the multi-level phase diffractive grating is etched, the incidence beam on the cell appears as an encoding image. When the encoded grating and DMH are used in the same label synchronously, the technology of multi-encoded grating array enhances the anti-counterfeit ability.

  7. Design of Arrayed-Waveguide Grating Routers for use as optical OFDM demultiplexers.

    Science.gov (United States)

    Lowery, Arthur James

    2010-06-21

    All-optical OFDM uses optical techniques to multiplex together several modulated lightsources, to form a band of subcarriers that can be considered as one wavelength channel. The subcarriers have a frequency separation equal to their modulation rate. This means that they can be demultiplexed without any cross-talk between them, usually with a Discrete Fourier Transform (DFT), implemented optically or electronically. Previous work has proposed networks of optical couplers to implement the DFT. This work shows that the topology of an Arrayed Grating Waveguide Router (AWGR) can be used to perform the demultiplexing, and that the AWGR can be considered as a serial-to-parallel converter followed by a DFT. The simulations show that the electrical bandwidths of the transmitter and receiver are critical to orthogonal demultiplexing, and give insight into how crosstalk occurs in all-optical OFDM and coherent-WDM systems using waveforms and spectra along the system. Design specifications for the AWGR are developed, and show that non-uniformity will lead to crosstalk. The compensation of dispersion and the applications of these techniques to 'coherent WDM' systems using Non-Return to Zero modulation is discussed.

  8. Multiplex and simultaneous measurement of displacement and temperature using tapered fiber and fiber Bragg grating

    Energy Technology Data Exchange (ETDEWEB)

    Ji Chongke; Zhao Chunliu; Kang Juan; Dong Xinyong; Jin Shangzhong [Institute of Optoelectronic Technology, China Jiliang University, Hangzhou 310018 (China)

    2012-05-15

    A simple method to work out the multiplexing of tapered fiber based sensors is proposed and demonstrated. By cascading a tapered fiber with a fiber Bragg grating (FBG), the sensor head is provided with a wavelength identification, different FBGs provide the sensor heads with different reflective peaks and they can be distinguished in optical spectrum. By compositing several such sensor heads with a multi-channel beam splitter, a star-style topological structure sensor for multipoint sensing is achieved. At the same time, the output intensity at the peak wavelength is sensitive to one external physical parameter applied on the related FBG-cascaded tapered fiber and the central wavelength of the peak is only sensitive to temperature, so that that parameter and temperature can be measured simultaneously. A sensor for dual-point measurement of the displacement and temperature simultaneously is experimentally demonstrated by using a 2 x 2 coupler in this paper. Experiment results show that the sensor works well and the largest sensitivities reach to 0.11 dB/{mu}m for displacement in the range of 0-400 {mu}m, and {approx}0.0097 nm/ deg. C for temperature between 20 deg. C and 70 deg. C.

  9. Tunable Fiber Bragg Grating Ring Lasers using Macro Fiber Composite Actuators

    Science.gov (United States)

    Geddis, Demetris L.; Allison, Sidney G.; Shams, Qamar A.

    2006-01-01

    The research reported herein includes the fabrication of a tunable optical fiber Bragg grating (FBG) fiber ring laser (FRL)1 from commercially available components as a high-speed alternative tunable laser source for NASA Langley s optical frequency domain reflectometer (OFDR) interrogator, which reads low reflectivity FBG sensors. A Macro-Fiber Composite (MFC) actuator invented at NASA Langley Research Center (LaRC) was selected to tune the laser. MFC actuators use a piezoelectric sheet cut into uniaxially aligned rectangular piezo-fibers surrounded by a polymer matrix and incorporate interdigitated electrodes to deliver electric fields along the length of the piezo-fibers. This configuration enables MFC actuators to produce displacements larger than the original uncut piezoelectric sheet. The FBG filter was sandwiched between two MFC actuators, and when strained, produced approximately 3.62 nm of wavelength shift in the FRL when biasing the MFC actuators from 500 V to 2000 V. This tunability range is comparable to that of other tunable lasers and is adequate for interrogating FBG sensors using OFDR technology. Three different FRL configurations were studied. Configuration A examined the importance of erbium-doped fiber length and output coupling. Configuration B demonstrated the importance of the FBG filter. Configuration C added an output coupler to increase the output power and to isolate the filter. Only configuration C was tuned because it offered the best optical power output of the three configurations. Use of Plastic Optical Fiber (POF) FBG s holds promise for enhanced tunability in future research.

  10. Iridescence in Meat Caused by Surface Gratings

    Directory of Open Access Journals (Sweden)

    Ali Kemal Yetisen

    2013-11-01

    Full Text Available The photonic structure of cut muscle tissues reveals that the well-ordered gratings diffract light, producing iridescent colours. Cut fibrils protruding from the muscle surface create a two-dimensional periodic array, which diffract light at specific wavelengths upon illumination. However, this photonic effect misleads consumers in a negative way to relate the optical phenomenon with the quality of the product. Here we discuss the fundamentals of this optical phenomenon and demonstrate a methodology for quantitatively measuring iridescence caused by diffraction gratings of muscle tissue surface of pork (Sus scrofa domesticus using reflection spectrophotometry. Iridescence was discussed theoretically as a light phenomenon and spectral measurements were taken from the gratings and monitored in real time during controlled drying. The findings show that the intensity of diffraction diminishes as the surface grating was dried with an air flow at 50 °C for 2 min while the diffracted light wavelength was at 585 ± 9 nm. Our findings indicate that the diffraction may be caused by a blazed surface grating. The implications of the study include providing guidelines to minimise the iridescence by altering the surface microstructure, and in consequence, removing the optical effect.

  11. Arc-Induced Long Period Fiber Gratings

    Directory of Open Access Journals (Sweden)

    Gaspar Rego

    2016-01-01

    Full Text Available Long period fiber gratings produced by the electric arc technique have found an increasing interest by the scientific community due to their ease to fabricate, virtually enabling the inscription in any kind of fiber, low cost, and flexibility. In 2005 we have presented the first review on this subject. Since then, important achievements have been reached such as the identification of the mechanisms responsible for gratings formation, the type of symmetry, the conditions to increase fabrication reproducibility, and their inscription in the turning points with grating periods below 200 μm. Several interesting applications in the sensing area, including those sensors working in reflection, have been demonstrated and others are expected, namely, related to the monitoring of extreme temperatures, cryogenic and high temperatures, and high sensitivity refractometric sensors resulting from combining arc-induced gratings in the turning points and the deposition of thin films in the transition region. Therefore, due to its pertinence, in this paper we review the main achievements obtained concerning arc-induced long period fiber gratings, with special focus on the past ten years.

  12. Ultra-compact three-port trench-based photonic couplers in ion-exchanged glass waveguides

    Science.gov (United States)

    Liu, Ke; Huang, Hui; Mu, Si Xuan; Lin, Hai; MacFarlane, Duncan L.

    2013-11-01

    An ultra-compact three-port photonic coupler is proposed on a glass substrate based upon a principle of frustrated total internal reflection. A single slash shape narrow trench at the “T” intersection of two ion-exchanged waveguides forms the coupler and is aligned 45° to the waveguides. The three-dimensional finite difference time domain (FDTD) theory is used to simulate the parameterization of the coupler, such as splitting ratios and efficiency versus trench widths, trench lengths, trench locations, and trench angles. The waveguide model used in FDTD is based on an experimental condition of the K+-Na+ ion-exchange process. A single-mode 6 μm wide glass waveguide at 1550 nm wavelength is fabricated through the analysis of the effective index method. The numerical results show that the arbitrary splitting ratios may be controlled by trench widths and trench angles. Comparing to Si, InP and GaAs materials, trench-based coupler on glasses may readily achieve the manufacturability since the low index of glass waveguides results in a wider trench opening. Taking advantage of low loss ion-exchanged waveguides, the high efficiency and short interaction length photonic couplers have a great potential to be integrated for large scale glass-based photonic circuits.

  13. III-Nitride grating grown on freestanding HfO2 gratings

    Directory of Open Access Journals (Sweden)

    Wu Tong

    2011-01-01

    Full Text Available Abstract We report here the epitaxial growth of III-nitride material on freestanding HfO2 gratings by molecular beam epitaxy. Freestanding HfO2 gratings are fabricated by combining film evaporation, electron beam lithography, and fast atom beam etching of an HfO2 film by a front-side silicon process. The 60-μm long HfO2 grating beam can sustain the stress change during the epitaxial growth of a III-nitride material. Grating structures locally change the growth condition and vary indium composition in the InGaN/GaN quantum wells and thus, the photoluminescence spectra of epitaxial III-nitride grating are tuned. Guided mode resonances are experimentally demonstrated in fabricated III-nitride gratings, opening the possibility to achieve the interaction between the excited light and the grating structure through guided mode resonance. PACS: 78.55.Cr; 81.65.Cf; 81.15.Hi.

  14. High-index-contrast subwavelength grating VCSEL

    DEFF Research Database (Denmark)

    Gilet, Philippe; Olivier, Nicolas; Grosse, Philippe

    2010-01-01

    In this article, we report our results on 980nm high-index-contrast subwavelength grating (HCG) VCSELs for optical interconnection applications. In our structure, a thin undoped HCG layer replaces a thick p-type Bragg mirror. The HCG mirror can feasibly achieve polarization-selective reflectivities...... close to 100%. The investigated structure consists of a HCG mirror with an underneath /4-thick oxide gap, four p-type GaAlAs/GaAs pairs for current spreading, three InGaAs/GaAs quantum wells, and an n-type GaAlAs/GaAs Bragg mirror. The HCG structure was defined by e-beam lithography and dry etching....... The current oxide aperture and the oxide gap underneath the HCG were simultaneously formed by the selective wet oxidation process. Compared to air-gap high contrast grating mirrors demonstrated elsewhere, our grating mirrors are particular since they are supported by thinner /4 aluminium oxide layer, and thus...

  15. Development of Aspherical Active Gratings at NSRRC

    Science.gov (United States)

    Tseng, Tse-Chuan; Wang, Duan Jen; Perng, Shen-Yaw; Chen, Chien-Te; Lin, Chia-Jui; Kuan, Chien-Kuang; Ho, His-Chou; Wang, Jeremy; Fung, H. S.; Chang, Shuo-Hung

    2007-01-01

    An active grating based on a novel optical concept with bendable polynomial surface profile to reduce the coma and defocus aberrations had been designed and proved by the prototype testing. Due to the low glass transition temperature of the glue and the difference of thermal expansion coefficient between the 17-4 steel bender and silicon, the prototype distorted from flat polished condition when thermally de-blocked the polishing pitch. To improve the thermal deformation of the active grating in the polishing process, a new invar bender and high curing temperature glue were adapted to glue a silicon substrate on the bender. After some tests and manufacturer polishing, it showed acceptable conditions. In this paper we will present the design and preliminary tests of the invar active grating. Meanwhile, the design and analysis of a new 17-4 PH steel bender to be electro-less nickel plating and mechanical ruling for a new beamline will also be discussed.

  16. Theoretical analysis on x-ray cylindrical grating interferometer

    CERN Document Server

    Cong, Wenxiang; Wang, Ge

    2015-01-01

    Grating interferometer is a state of art x-ray imaging approach, which can simultaneously acquire information of x-ray attenuation, phase shift, and small angle scattering. This approach is very sensitive to micro-structural variation and offers superior contrast resolution for biological soft tissues. The present grating interferometer often uses flat gratings, with serious limitations in the field of view and the flux of photons. The use of curved gratings allows perpendicular incidence of x-rays on the gratings, and gives higher visibility over a larger field of view than a conventional interferometer with flat gratings. In the study, we present a rigorous theoretical analysis of the self-imaging of curved transmission gratings based on Rayleigh-Sommerfeld diffraction. Numerical simulations have demonstrated the self-imaging phenomenon of cylindrical grating interferometer. The theoretical results are in agreement with the results of numerical simulations.

  17. Strongly Dispersive Transient Bragg Grating for High Harmonics

    Energy Technology Data Exchange (ETDEWEB)

    Farrell, J.; Spector, L.S.; /SLAC, PULSE /Stanford U., Phys. Dept. /Stanford U., Appl. Phys. Dept.; Gaarde, M.B.; /SLAC, PULSE /Louisiana State U.; McFarland, B.K.; Bucksbaum, P.H.; Guhr, Markus; /SLAC, PULSE /Stanford U., Phys. Dept. /Stanford U., Appl. Phys. Dept.

    2010-06-04

    We create a transient Bragg grating in a high harmonic generation medium using two counterpropagating pulses. The Bragg grating disperses the harmonics in angle and can diffract a large bandwidth with temporal resolution limited only by the source size.

  18. Polymeric waveguide Bragg grating filter using soft lithography

    Science.gov (United States)

    Kocabas, Askin; Aydinli, Atilla

    2006-10-01

    We use the soft lithography technique to fabricate a polymeric waveguide Bragg grating filter. Master grating structure is patterned by e-beam lithography. Using an elastomeric stamp and capillary action, uniform grating structures with very thin residual layers are transferred to the UV curable polymer without the use of an imprint machine. The waveguide layer based on BCB optical polymer is fabricated by conventional optical lithography. This approach provides processing simplicity to fabricate Bragg grating filters.

  19. Transmission grating stretcher for contrast enhancement of high power lasers.

    Science.gov (United States)

    Tang, Yunxin; Hooker, Chris; Chekhlov, Oleg; Hawkes, Steve; Collier, John; Rajeev, P P

    2014-12-01

    We propose, for the first time, a transmission grating stretcher for high power lasers and demonstrate its superiority over conventional, reflective gold grating stretchers in terms of pulse temporal quality. We show that, compared to a conventional stretcher with the same stretching factor, the transmission-grating based stretcher yields more than an order of magnitude improvement in the contrast pedestal. We have also quantitatively characterized the roughness of the grating surfaces and estimated its impact on the contrast pedestal.

  20. Multiwavelength optical scatterometry of dielectric gratings

    KAUST Repository

    Yashina, Nataliya P.

    2012-08-01

    Modern scatterometry problems arising in the lithography production of periodic gratings are in the focus of the work. The performance capabilities of a novel theoretical and numerical modeling oriented to these problems are considered. The approach is based on rigorous solutions of 2-D initial boundary value problems of the gratings theory. The quintessence and advantage of the method is the possibility to perform an efficient analysis simultaneously and interactively both for steady state and transient processes of the resonant scattering of electromagnetic waves by the infinite and compact periodic structures. © 2012 IEEE.

  1. Novel algorithm for synthesis of fiber gratings

    Institute of Scientific and Technical Information of China (English)

    Bo LV; Ming CHEN; Dan LU; Taorong GONG; Tangjun LI; Shuisheng JIAN

    2009-01-01

    A novel algorithm for the synthesis of fiber gratings is presented.For the first time we propose an effective optimal approach to construct a coupling coefficient function by employing 4th-order Runge-Kutta (R-K) analysis method for calculating the reflection spectra of fiber gratings.The numerical results show that with this proposed method, some required optical filters have been yielded with better features compared with other methods such as Gel'Fand-Levitan-Marchenko (GLM) algorithm.In addition, the performance of different interpolation functions particularly utilized in our algorithm, including linear-type, spline-type, and Hermit-type, are discussed in detail.

  2. Sangac interferometer on the holographic bragg grating

    CERN Document Server

    Tikhonov, E A

    2015-01-01

    The ring interferometer with zero optical path difference known as Sagnac one is offered with a diffraction splitting of the entering light beam. As the beamsplitter, a transmission holographic Bragg grating is used. Conditions of normal operation of this interferometer achieve under the equal intensity of beam copies and the adjustable phase shift between them in its two interferometer shoulders. These conditions are met with the holographic grating, which provides the phase shift 180^0 on the central Bragg wavelength. Experimental approbation of the modified interferometer validates the expected results.

  3. Solitary wave generation from continuum in asymmetric oppositely directed nonlinear waveguide coupler

    Science.gov (United States)

    Kazantseva, E. V.; Maimistov, A. I.

    2016-08-01

    In a model which describes asymmetric oppositely directed nonlinear waveguide coupler it was observed in the numerical simulation a phenomenon of solitary wave formation from the input constant continuous wave set at the entrance of a waveguide with negative index of refraction. Threshold value of the amplitude of the constant continuous wave, which defines the condition of appearance of the first solitary wave, decreases with increasing of the parameter of nonlinearity. The period of solitary wave formation decreases with increasing of the continuum wave amplitude.

  4. Analyzing the effects of post couplers in DTL tuning by the equivalent circuit model

    OpenAIRE

    Jia, Xiaoyu; Zheng, Shuxin

    2013-01-01

    Stabilization of the accelerating field in Drift Tube Linac(DTL) is obtained by inserting Post Couplers(PCs).On the basis of the circuit model equivalent for the DTL with and without asymmetrical PCs, stabilization is deduced quantitatively: let $\\delta \\omega/\\omega_0$ be the relative frequency error, then we discover that the sensitivity of field to perturbation is proportional to $\\sqrt{\\delta \\omega / \\omega_0}$ without PCs and to $\\delta \\omega/\\omega_0$ with PCs. Then we adapt the circu...

  5. DESIGN OF V-BAND SUBSTRATE INTEGRATED WAVEGUIDE POWER DIVIDER, CIRCULATOR AND COUPLER

    Directory of Open Access Journals (Sweden)

    Bouchra Rahali

    2013-11-01

    Full Text Available Recently there is growing interest in a new technology, substrate integrated waveguide (SIW, it has been applied successfully to the conception of planar compact components for the microwave and millimeter waves applications. In this study, a V-band substrate integrated waveguide power divider, circulator and coupler are conceived and optimized by Ansoft HFSS code. Thus, through this modeling, design considerations and results are discussed and presented. Attractive features including compact size and planar form make these devices structure easily integrated in planar circuits.

  6. Frequency support capability of variable speed wind turbine based on electromagnetic coupler

    DEFF Research Database (Denmark)

    You, Rui; Barahona Garzón, Braulio; Chai, Jianyun;

    2015-01-01

    In the variable speed wind turbine based on electromagnetic coupler (WT-EMC), a synchronous generator is directly coupled with grid. So like conventional power plants WT-EMC is able to support grid frequency inherently. But due to the reduced inertia of synchronous generator, its frequency support...... capability has to be enhanced. In this paper, the frequency support capability of WT-EMC is studied at three typical wind conditions and with two control strategies-droop control and inertial control to enhance its frequency support capability. The synchronous generator speed, more stable than the grid...

  7. Expansive cement couplers: A means of pre-tensioning fibre-reinforced plastic tendons

    OpenAIRE

    1995-01-01

    This is the peer reviewed version of: Lees J.M., Gruffydd-Jones, B. and Burgoyne C.J. (1995) "Expansive Cement Couplers - A Means of Pre-tensioning Fibre-Reinforced Plastic Tendons", published in 'Construction and Building Materials', v. 9, is. 6, pp. 413-423 December 1995. The published version is at http://dx.doi.org/10.1016/0950-0618(95)00070-4 Fibre reinforced plastics describes a group of materials composed of inorganic or organic fibres embedded in a resin matrix. frps are strong, n...

  8. Bistable soliton states and switching in doubly inhomogeneously doped fiber couplers

    Indian Academy of Sciences (India)

    Ajit Kumar

    2001-11-01

    Switching between the bistable soliton states in a doubly and inhomogeneously doped fiber system is studied numerically. Both the cases of lossless as well as lossy couplers are considered. It is shown that both up-switching (from the low state to the high state) and down-switching (from the high state to the low state) of solitons between bistable states are realizable, if the amplification of the input soliton for up-switching and the extraction of energy from it for down-switching are suitably adjusted.

  9. Experience with the Vibrant Soundbridge RW-Coupler for round window Vibroplasty with tympanosclerosis

    OpenAIRE

    Iwasaki, Satoshi; Suzuki, Hiroaki; Moteki, Hideaki; Miyagawa, Maiko; Takumi, Yutaka; Usami, Shin-ichi

    2012-01-01

    Usage of the Vibrant Soundbridge (VSB) with round window (RW)-Coupler placement at the RW has been shown to successfully treat mixed hearing loss. Coupling between the VSB's floating mass transducer (FMT) and the RW membrane is difficult in the case of sclerosis in the RW and drilling down the bony lip until the RW membrane can be seen completely can possibly induce a perilymphatic fistula. A 68-year-old woman who had bilateral mixed hearing loss with sclerosis in the RW due to tympanoscleros...

  10. Circuit Methods for VLF Antenna Couplers. [for use in Loran or Omega receiver systems

    Science.gov (United States)

    Burhans, R. W.

    1977-01-01

    The limitations of different E-field antenna coupler or preamplifier circuits are presented. All circuits were evaluated using actual Loran or Omega signals. Electric field whip or wire antennas are the simplest types which can be used for reception of VLF signals in the 10 to 100 kHz range. JFET or MOSFET transistors provide impedance transformation and some voltage gain in simple circuits where the power for operating the preamplifier uses the same coaxial cable that feeds the signal back to the receiver. The circuit techniques provide useful alternative methods for Loran-Omega receiver system designers.

  11. Very high coupling of TM polarised light in photonic crystal directional couplers

    DEFF Research Database (Denmark)

    Borel, Peter Ingo; Thorhauge, Morten; Frandsen, Lars Hagedorn;

    2003-01-01

    noteworthy is the transmission level, experimentally found to be above -3 dB in the wavelength range 1520-1690 nm, for TM polarised light in the coupled channel. It is noted that even though band calculations show that the propagation of the TM polarisation takes place below the TM valence band, very high......The experimental and simulated spectra for TE and TM polarised light for the transmission through photonic crystal directional couplers are presented. The 3D FDTD simulations successfully explain all the major features of the experimental spectra as well as the actual transmission level. Especially...

  12. In-situ characterization of spurious modes in HE11 transmission lines with a 5-port coupler

    Directory of Open Access Journals (Sweden)

    Tretiak D.

    2012-09-01

    Full Text Available Real-time in-situ measurement of spurious modes in HE11 transmission lines is becoming an important topic for the design of next-generation ECRH installations (e.g. ITER, because the acceptable tolerances for the alignment of the waveguides and coupling optics are small for oversized waveguides. Also, the effects of spurious modes (ohmic heating, wrong beam parameters at the launcher become increasingly critical. We present a method for in-situ characterization of 4 dominant spurious modes by using a 5-port coupler, which is integrated into a miter bend. The coupler signals can be directly transformed into the mode spectrum by a matrix multiplication. A general formalism for obtaining the coefficients of the transformation matrix is presented along with a method for optimizing the coupler positions in order to obtain the maximum dynamic range for the diagnostics.

  13. Semi-Analytical Simulation of Titanium-Indiffused Lithium Niobate-Integrated Optic Directional Couplers Consisting of Curved Waveguides

    Science.gov (United States)

    Ganguly, Pranabendu; Biswas, Juran Chandra; Lahiri, Samir Kumar

    Integrated optic directional couplers consisting of curved waveguides are simulated analytically by solving the Riccati equation. The coupling coefficient between the curved waveguides with a parabolically varying gap and the condition of total power transfer between the waveguides are derived. In order to compute the overall coupling coefficient and hence the power distribution along the waveguides for Ti:LiNbO3 curved waveguide directional couplers, the coupling coefficient for straight waveguide couplers is computed for different gaps using the effective-index-based matrix method (EIMM). Finally, the power distribution in the curved waveguides along the length is computed. The method is mostly analytical except the effective-index method and is computationally simple.

  14. All-optical logical gates based on pump-induced resonant nonlinearity in an erbium-doped fiber coupler.

    Science.gov (United States)

    Li, Qiliang; Zhang, Zhen; Li, Dongqiang; Zhu, Mengyun; Tang, Xianghong; Li, Shuqin

    2014-12-01

    In this paper, we theoretically investigate all-optical logical gates based on the pump-induced resonant nonlinearity in an erbium-doped fiber coupler. The resonant nonlinearity yielded by the optical transitions between the (4)I(15/2) states and (4)I(13/2) states in Er(3+) induces the refractive index to change, which leads to switching between two output ports. First, we do a study on the switching performance, and calculate the extinction ratio (Xratio) of the device. Second, using the Xratio, we obtain the truth tables of the device. The results reveal that compared with other undoped nonlinear couplers, the erbium-doped fiber coupler can drop the switching threshold power. We also obtain different logic gates and logic operations in the cases of the same phase and different phase of two initial signals by changing the pump power.

  15. Light scanner based on a viscoelastic stretchable grating

    NARCIS (Netherlands)

    Simonov, A.N.; Akhzar-Mehr, O.; Vdovine, G.V.

    2005-01-01

    We present a new technique for light scanning by use of viscoelastic-based deformable phase diffraction gratings. Mechanical stretching of the grating permits control of its spatial period, and thus the orders of diffraction can be spatially deflected. In the experiments the viscoelastic gratings wi

  16. Liquid filling of photonic crystal fibres for grating writing

    DEFF Research Database (Denmark)

    Sørensen, Henrik Rokkjær; Canning, John; Lægsgaard, Jesper;

    2007-01-01

    liquid filling of photonic crystal fibres reduces the scattering from air–glass interfaces during Bragg grating writing in many layered photonic crystal fibres. Within experimental uncertainty, the grating index modulation of a grating written in germanium-doped photonic crystal fibre with 10 rings...

  17. Fabrication of Dammann Gratings Inside Glasses by a Femtosecond Laser

    Institute of Scientific and Technical Information of China (English)

    NAKAYA Takayuki; QIU Jian-Rong; ZHOU Chang-He; HIRAO Kazuyuki

    2004-01-01

    @@ Dammann grating is useful in information technology as an optical splitter. It is usually fabricated through complicated processes. Here we report on the direct fabrication of a 6 × 6 Dammann grating in a silica glass by an 800nm femtosecond laser. We also discuss the relationship between diffraction efficiency of 1 × 2 Dammann grating and laser irradiation conditions.

  18. Light scanner based on a viscoelastic stretchable grating

    NARCIS (Netherlands)

    Simonov, A.N.; Akhzar-Mehr, O.; Vdovine, G.V.

    2005-01-01

    We present a new technique for light scanning by use of viscoelastic-based deformable phase diffraction gratings. Mechanical stretching of the grating permits control of its spatial period, and thus the orders of diffraction can be spatially deflected. In the experiments the viscoelastic gratings wi

  19. Off-plane x-ray reflection grating fabrication

    Science.gov (United States)

    Peterson, Thomas J.; DeRoo, Casey T.; Marlowe, Hannah; McEntaffer, Randall L.; Miles, Drew M.; Tutt, James H.; Schultz, Ted B.

    2015-09-01

    Off-plane X-ray diffraction gratings with precision groove profiles at the submicron scale will be used in next generation X-ray spectrometers. Such gratings will be used on a current NASA suborbital rocket mission, the Off-plane Grating Rocket Experiment (OGRE), and have application for future grating missions. The fabrication of these gratings does not come without challenges. High performance off-plane gratings must be fabricated with precise radial grating patterns, optically at surfaces, and specific facet angles. Such gratings can be made using a series of common micro-fabrication techniques. The resulting process is highly customizable, making it useful for a variety of different mission architectures. In this paper, we detail the fabrication method used to produce high performance off-plane gratings and report the results of a preliminary qualification test of a grating fabricated in this manner. The grating was tested in the off-plane `Littrow' configuration, for which the grating is most efficient for a given diffraction order, and found to achieve 42% relative efficiency in the blaze order with respect to all diffracted light.

  20. Null Fiber Coupler with Ultra-high Splitting Ratio of 100000:1 for All-fiber Acousto-optic Switch

    Institute of Scientific and Technical Information of China (English)

    LI Tong; PENG Jiangde; LI Qun; LIU Xiaoming

    2000-01-01

    A fiber null coupler with very high splitting ratio of 100000: 1 and low excess loss of 0.1 dB is reported. The control of the maximum splitting ratio and loss of the null coupler is studied. Its switching function is experimentally demonstrated by acousto-optic modulation.

  1. All-optical switching in a symmetric three-waveguide coupler with phase-mismatched absorptive central waveguide.

    Science.gov (United States)

    Chen, Yijing; Ho, Seng-Tiong; Krishnamurthy, Vivek

    2013-12-20

    All-optical switching operation based on manipulation of absorption in a three-waveguide directional coupler is theoretically investigated. The proposed structure consists of one absorptive central waveguide and two identical passive side waveguides. Optically induced absorption change in the central waveguide effectively controls the coupling of light between the two side waveguides, leading to optical switching action. The proposed architecture alleviates the fabrication challenges and waveguide index matching conditions that limit previous demonstrations of similar switching schemes based on a two-waveguide directional coupler. The proposed device accommodates large modal index difference between absorptive and passive waveguides without compromising the switching extinction ratio.

  2. Monolithically integrated self-rolled-up microtube-based vertical coupler for three-dimensional photonic integration

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Xin; Arbabi, Ehsan; Goddard, Lynford L.; Li, Xiuling; Chen, Xiaogang, E-mail: oxgchen@illinois.edu [Department of Electrical and Computer Engineering, University of Illinois, Urbana, Illinois 61801 (United States)

    2015-07-20

    We demonstrate a self-rolled-up microtube-based vertical photonic coupler monolithically integrated on top of a ridge waveguide to achieve three-dimensional (3D) photonic integration. The fabrication process is fully compatible with standard planar silicon processing technology. Strong light coupling between the vertical coupler and the ridge waveguide was observed experimentally, which may provide an alternative route for 3D heterogeneous photonic integration. The highest extinction ratio observed in the transmission spectrum passing through the ridge waveguide was 23 dB.

  3. 1.28 Tbaud Nyquist-OTDM Transmission over a 7-Core Fiber Using an On-Chip SDM Coupler

    DEFF Research Database (Denmark)

    Hu, Hao; Medhin, Ashenafi Kiros; Ye, Feihong

    2014-01-01

    We have demonstrated the first 1.28-Tbaud Nyquist-OTDM-SDM transmission over a 67.4 - km seven-core fiber with an aggregated data rate of 7.2 Tbit/s using a silicon SDM coupler. 10 - GHz control pulses were transmitted through the center core......We have demonstrated the first 1.28-Tbaud Nyquist-OTDM-SDM transmission over a 67.4 - km seven-core fiber with an aggregated data rate of 7.2 Tbit/s using a silicon SDM coupler. 10 - GHz control pulses were transmitted through the center core...

  4. Theory of optimal beam splitting by phase gratings. I. One-dimensional gratings.

    Science.gov (United States)

    Romero, Louis A; Dickey, Fred M

    2007-08-01

    We give an analytical basis for the theory of optimal beam splitting by one-dimensional gratings. In particular, we use methods from the calculus of variations to derive analytical expressions for the optimal phase function.

  5. Smart photogalvanic running-grating interferometer

    DEFF Research Database (Denmark)

    Kukhtarev, N. V.; Kukhtareva, T.; Edwards, M. E.

    2005-01-01

    Photogalvanic effect produces actuation of periodic motion of macroscopic LiNbO3 crystal. This effect was applied to the development of an all-optical moving-grating interferometer usable for optical trapping and transport of algae chlorella microorganisms diluted in water with a concentration of...

  6. Gratings in plasmonic V-groove waveguides

    DEFF Research Database (Denmark)

    Smith, Cameron; Cuesta, Irene Fernandez; Kristensen, Anders

    2011-01-01

    We introduce visible light optical gratings to surface plasmon V-groove waveguides. Gradient e-beam dosage onto silicon stamp enables structuring V-grooves of varying depth. Nanoimprint lithography maintains a Λ=265 nm corrugation for gold surface devices....

  7. Speed enhancement in VCSELs employing grating mirrors

    DEFF Research Database (Denmark)

    Chung, Il-Sug; Mørk, Jesper

    2013-01-01

    In recent years, various approaches to improve the speed of directly modulated vertical-cavity surface-emitting lasers (VCSELs) have been reported and demonstrated good improvement. In this paper, we propose and numerically investigate a new possibility of using high-index-contrast grating (HCG...

  8. Exciton-polaritons in Bragg gratings

    Energy Technology Data Exchange (ETDEWEB)

    Creatore, C [Department of Physics ' A. Volta' , Universita di Pavia, via Bassi 6, I-27100, Pavia (Italy); Mouchliadis, L; Langbein, W [School of Physics and Astronomy, Cardiff University, The Parade, CF24 3AA, Cardiff (United Kingdom); Biancalana, F [Max Planck Institute for the Science of Light, Guenther-Scharowsky-Str. 1/Bau 24, 91058 Erlangen (Germany); Osborne, S, E-mail: creatore@fisicavolta.unipv.i [Tyndall National Institute, Lee Maltings, Prospect Row, Cork (Ireland)

    2010-02-01

    We study the strong coupling between photons and bulk excitons in a one-dimensional Bragg grating. The dispersion of the resulting Bragg-polariton states resembles the dispersion of quantum-well microcavity polaritons. We report on a parametric scattering process at two 'magic frequencies' occurring due to the strong excitonic nonlinearity.

  9. Hybrid grating reflectors: Origin of ultrabroad stopband

    Energy Technology Data Exchange (ETDEWEB)

    Park, Gyeong Cheol; Taghizadeh, Alireza; Chung, Il-Sug, E-mail: ilch@fotonik.dtu.dk [DTU Fotonik, Department of Photonics Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark)

    2016-04-04

    Hybrid grating (HG) reflectors with a high-refractive-index cap layer added onto a high contrast grating (HCG) provide a high reflectance close to 100% over a broader wavelength range than HCGs. The combination of a cap layer and a grating layer brings a strong Fabry-Perot (FP) resonance as well as a weak guided mode (GM) resonance. Most of the reflected power results from the FP resonance, while the GM resonance plays a key role in achieving a reflectance close to 100% as well as broadening the stopband. An HG sample with 7 InGaAlAs quantum wells included in the cap layer has been fabricated by directly wafer-bonding a III-V cap layer onto a Si grating layer. Its reflection property has been characterized. This heterogeneously integrated HG reflector may allow for a hybrid III-V on Si laser to be thermally efficient, which has promising prospects for silicon photonics light sources and high-speed operation.

  10. Gratings in plasmonic V-groove waveguides

    DEFF Research Database (Denmark)

    Smith, Cameron; Cuesta, Irene Fernandez; Kristensen, Anders

    2011-01-01

    We introduce visible light optical gratings to surface plasmon V-groove waveguides. Gradient e-beam dosage onto silicon stamp enables structuring V-grooves of varying depth. Nanoimprint lithography maintains a Λ=265 nm corrugation for gold surface devices....

  11. Undergraduate Experiment with Fractal Diffraction Gratings

    Science.gov (United States)

    Monsoriu, Juan A.; Furlan, Walter D.; Pons, Amparo; Barreiro, Juan C.; Gimenez, Marcos H.

    2011-01-01

    We present a simple diffraction experiment with fractal gratings based on the triadic Cantor set. Diffraction by fractals is proposed as a motivating strategy for students of optics in the potential applications of optical processing. Fraunhofer diffraction patterns are obtained using standard equipment present in most undergraduate physics…

  12. Concave diffraction gratings fabricated with planar lithography

    NARCIS (Netherlands)

    Grabarnik, S.; Emadi, A.; Wu, H.; De Graaf, G.; Wolffenbuttel, R.F.

    2008-01-01

    This paper reports on the development and validation of a new technology for the fabrication of variable line-spacing non-planar diffraction gratings to be used in compact spectrometers. The technique is based on the standard lithographic process commonly used for pattern transfer onto a flat substr

  13. Improved performance of traveling wave directional coupler modulator based on electro-optic polymer

    CERN Document Server

    Zhang, Xingyu; Lin, Che-yun; Wang, Alan X; Hosseini, Amir; Lin, Xiaohui; Chen, Ray T

    2014-01-01

    Polymer based electro-optic modulators have shown great potentials in high frequency analog optical links. Existing commercial LiNibO3 Mach-Zehnder modulators have intrinsic drawbacks in linearity to provide high fidelity communication. In this paper, we present the design, fabrication and characterization of a traveling wave directional coupler modulator based on electro-optic polymer, which is able to provide high linearity, high speed, and low optical insertion loss. A silver ground electrode is used to reduce waveguide sidewall roughness due to the scattering of UV light in photolithography process in addition to suppressing the RF loss. A 1-to-2 multi-mode interference 3dB-splitter, a photobleached refractive index taper and a quasi-vertical taper are used to reduce the optical insertion loss of the device. The symmetric waveguide structure of the MMI-fed directional coupler is intrinsically bias-free, and the modulation is obtained at the 3-dB point regardless of the ambient temperature. By achieving lo...

  14. Performance improvement of optical fiber coupler with electric heating versus gas heating.

    Science.gov (United States)

    Shuai, Cijun; Gao, Chengde; Nie, Yi; Peng, Shuping

    2010-08-20

    Gas heating has been widely used in the process of fused biconical tapering. However, as the instability and asymmetric flame temperature of gas heating exist, the performance of the optical devices fabricated by this method was affected. To overcome the problems resulting from gas combustion, an electric heater is designed and manufactured using a metal-ceramic (MoSi(2)) as a heating material. Our experimental data show that the fused-taper machine with an electric heater has improved the performance of optical devices by increasing the consistency of the extinction ratio, excess loss, and the splitting ratio over that of the previous gas heating mode. Microcrystallizations and microcracks were observed at the fused region of the polarization-maintaining (PM) fiber coupler and at the taper region with scanning electron microscopy and atomic force microscopy respectively. The distribution of the microcrystallizations and microcracks are nonuniform along the fiber with gas heating, while their distribution is rather uniform with electric heating. These findings show that the novel optical fiber coupler with an electric heater has improved the performance of optical fiber devices by affecting the consistency of the optical parameters and micromorphology of the surface of PM fiber.

  15. Optical position encoder based on four-section diffraction grating

    Science.gov (United States)

    Zherdev, A. Y.; Odinokov, S. B.; Lushnikov, D. S.; Markin, V. V.; Gurylev, O. A.; Shishova, M. V.

    2017-05-01

    Optical position encoder consists of movable coding grating and fixed analyzing grating. Light passing and diffracting through these two gratings creates interference signal on optical detector. Decoding of interference signal phase allows to determinate current position. Known optical position encoders use several accurate adjusted optical channels and detectors to gather several signals with different phase for higher encoder accuracy. We propose to use one optical channel with several-section analyzing diffraction grating for this purpose to simplify optical scheme and adjusting requirements. Optical scheme of position encoder based on four-section analyzing diffraction grating is developed and described in this paper.

  16. Metrology measurements for large-aperture VPH gratings

    Science.gov (United States)

    Zheng, Jessica R.; Gers, Luke; Heijmans, Jeroen

    2013-09-01

    The High Efficiency and Resolution Multi Element Spectrograph (HERMES) for the Australian Astronomical Observatory (AAO) uses four large aperture, high angle of incidence volume phase holographic gratings (VPHG) for high resolution `Galactic archaeology' spectroscopy. The large clear aperture, the high diffraction efficiency, the line frequency homogeneity, and mosaic alignment made manufacturing and testing challenging. We developed new metrology systems at the AAO to verify the performance of these VPH gratings. The measured diffraction efficiencies and line frequency of the VPH gratings received so far meet the vendor's provided data. The wavefront quality for the Blue VPH grating is good but the Green and Red VPH gratings need to be post polishing.

  17. Field analysis of two-dimensional integrated optical gratings

    Science.gov (United States)

    Borsboom, P.-P.; Frankena, H. J.

    1995-05-01

    A rigorous technique to determine the field scattered by a two-dimensional rectangular grating made up of many corrugations was developed. In this method, the grating was deemed as a sequence of two types of waveguide sections, alternatingly connected by step discontinuities. A matrix was derived that described the entire rectangular grating by integrating the separate steps and waveguide sections. With the proposed technique, several configuration were analyzed. The obtained results showed good consistency with the consequences of previous studies. Furthermore, to examine the numerical stability of the proposed method, the length of the grating was increased and obtained results for a grating with 100 periods.

  18. Fiber-bragg grating-loop ringdown method and apparatus

    Science.gov (United States)

    Wang, Chuji

    2008-01-29

    A device comprising a fiber grating loop ringdown (FGLRD) system of analysis is disclosed. A fiber Bragg grating (FBG) or Long-Period grating (LPG) written in a section of single mode fused silica fiber is incorporated into a fiber loop. By utilizing the wing areas of the gratings' bandwidth as a wavelength dependent attenuator of the light transmission, a fiber grating loop ringdown concept is formed. One aspect of the present invention is temperature sensing, which has been demonstrated using the disclosed device. Temperature measurements in the areas of accuracy, stability, high temperature, and dynamic range are also described.

  19. Fundamental limit of light trapping in grating structures

    KAUST Repository

    Yu, Zongfu

    2010-08-11

    We use a rigorous electromagnetic approach to analyze the fundamental limit of light-trapping enhancement in grating structures. This limit can exceed the bulk limit of 4n 2, but has significant angular dependency. We explicitly show that 2D gratings provide more enhancement than 1D gratings. We also show the effects of the grating profile’s symmetry on the absorption enhancement limit. Numerical simulations are applied to support the theory. Our findings provide general guidance for the design of grating structures for light-trapping solar cells.

  20. Nanostructure Diffraction Gratings for Integrated Spectroscopy and Sensing

    Science.gov (United States)

    Guo, Junpeng (Inventor)

    2016-01-01

    The present disclosure pertains to metal or dielectric nanostructures of the subwavelength scale within the grating lines of optical diffraction gratings. The nanostructures have surface plasmon resonances or non-plasmon optical resonances. A linear photodetector array is used to capture the resonance spectra from one of the diffraction orders. The combined nanostructure super-grating and photodetector array eliminates the use of external optical spectrometers for measuring surface plasmon or optical resonance frequency shift caused by the presence of chemical and biological agents. The nanostructure super-gratings can be used for building integrated surface enhanced Raman scattering (SERS) spectrometers. The nanostructures within the diffraction grating lines enhance Raman scattering signal light while the diffraction grating pattern of the nanostructures diffracts Raman scattering light to different directions of propagation according to their wavelengths. Therefore, the nanostructure super-gratings allows for the use of a photodetector array to capture the surface enhanced Raman scattering spectra.

  1. First order Bragg grating filters in silicon on insulator waveguides

    Science.gov (United States)

    Waugh, Peter Michael

    2008-08-01

    The subject of this project is the design; analysis, fabrication and characterisation of first order Bragg Grating optical filters in Silicon-on-Insulator (SOI) planar waveguides. It is envisaged that this work will result in the possibility of Bragg Grating filters for use in Silicon Photonics. It is the purpose of the work to create as far as is possible flat surface waveguides so as to facilitate Thermo-Optic tuning and also the incorporation into rib-waveguide Silicon Photonics. The spectral response of the shallow Bragg Gratings was modelled using Coupled Mode Theory (CMT) by way of RSoft Gratingmod TM. Also the effect of having a Bragg Grating with alternate layers of refractive index of 1.5 and 3.5 was simulated in order to verify that Silica and Silicon layered Bragg Gratings could be viable. A series of Bragg Gratings were patterned on 1.5 micron SOI at Philips in Eindhoven, Holland to investigate the variation of grating parameters with a) the period of the gratings b) the mark to space ratio of the gratings and c) the length of the region converted to Bragg Gratings (i.e. the number of grating period repetitions). One set of gratings were thermally oxidised at Philips in Eindhoven and another set were ion implanted with Oxygen ions at the Ion Beam Facility, University of Surrey, England. The gratings were tested and found to give transmission minima at approximately 1540 nanometres and both methods of creating flat surfaces were found to give similar minima. Atomic Force Microscopy was applied to the grating area of the as-implanted samples in the Advanced Technology Institute, University of Surrey, which were found to have surface undulations in the order of 60 nanometres.

  2. Coupling analysis of non-circular-symmetric modes and design of orientation-insensitive few-mode fiber couplers

    Science.gov (United States)

    Li, Jiaxiong; Du, Jiangbing; Ma, Lin; Li, Ming-Jun; Jiang, Shoulin; Xu, Xiao; He, Zuyuan

    2017-01-01

    We study the coupling between two identical weakly-coupled few-mode fibers based on coupled-mode theory. The coupling behavior of non-circular-symmetric modes, such as LP11 and LP21, is investigated analytically and numerically. By carefully choosing the fiber core separation and coupler length, we can design orientation-insensitive fiber couplers for non-circular-symmetric modes at arbitrary coupling ratios. Based on the design method, we propose an orientation-insensitive two-mode fiber coupler at 850 nm working as a mode multiplexer/demultiplexer for two-mode transmission using standard single-mode fiber. Within the band from 845 to 855 nm, the insertion losses of LP01 and LP11 modes are less than 0.03 dB and 0.24 dB, respectively. When the two-mode fiber coupler is used as mode demultiplexer, the LP01/LP11 and LP11/LP01 extinction ratios in the separated branches are respectively above 12.6 dB and 21.2 dB. Our design method can be extended to two-mode communication or sensing systems at other wavelengths.

  3. Design and analysis of O-S-C triple band wavelength division demultiplexer using cascaded MMI couplers

    Science.gov (United States)

    Chack, Devendra; Kumar, V.; Raghuwanshi, Sanjeev Kumar; Singh, Dev Prakash

    2017-01-01

    Compact triple O-S-C band wavelength demultiplexer, which consists of series cascaded multimode interference (MMI) couplers has been carried out in this paper. The MMI coupler has been used to drop the wavelengths of 1510 nm and 1550 nm at bar port while the wavelength 1300 nm into the cross port. Then another MMI coupler has been designed to separate the wavelength 1510 nminto one port and wavelength 1550 nm into another port. The triple wavelength demultiplexer function has been performed by choosing a suitable refractive index of the guiding region and geometrical parameters such as the width and length of MMI coupler. Numerical simulation with finite difference beam propagation method (BPM) has been utilized to design and optimize the operation of the proposed triple wavelength demultiplexer. The simulation results show that insertion losses of wavelength O, S and C, bands are 1.884 dB, 1.452 dB and 2.568 dB, respectively, with isolations for each output waveguide ranging from 10 dB to 28.72 dB. The 3-dB bandwidth of insertion loss for 1300 nm, 1510 nm and 1550 nm are 80 nm, 20 nm and 10 nm, respectively.

  4. Multipacting Simulations of Tuner-adjustable waveguide coupler (TaCo) with CST Particle Studio®

    CERN Document Server

    Shafqat, N; Wegner, R

    2014-01-01

    Tuner-adjustable waveguide couplers (TaCo) are used to feed microwave power to different RF structures of LINAC4. This paper studies the multipacting phenomenon for TaCo using the PIC solver of CST PS. Simulations are performed for complete field sweeps and results are analysed.

  5. Finite element analysis of coupler carrier forming%车钩托板成形有限元分析

    Institute of Scientific and Technical Information of China (English)

    牛士军; 栾小东

    2015-01-01

    传统车钩托板采用热压成形工艺 ,工艺方法落后 ,生产效率低 ,耗能较大.本文通过DYNAFORM 有限元软件平台 ,对车钩托板冷压成形工艺进行模拟 ,分析其成形工艺特点 ,通过对成形、回弹过程的数值模拟 ,得到了车钩托板冷压成形的理论依据.经实践证明 :车钩托板冷压成形工艺 ,明显提高了生产效率并降低了耗能.%Traditionally ,thermoforming process is used to produce coupler carrier ,but it is of backward ,low productivity ,and large energy consumption .In this paper ,the cold form-ing process of coupler carrier was simulated to analyze the forming process characteristics based on finite element software platform DYNAFORM .Through the simulation of form-ing and springback process , the theoretical basis of cold forming of coupler carrier was obtained .Practice has proved that the cold forming process of coupler carrier can signifi-cantly improve productivity and reduce energy consumption .

  6. Experimental test of a supercritical helium heat exchanger dedicated to EUROTRANS 150 kW CW power coupler

    Science.gov (United States)

    Souli, M.; Fouaidy, M.; Hammoudi, N.

    2010-05-01

    The coaxial power coupler needed for beta = 0.65 superconducting RF cavities used in the high energy section of the EUROTRANS driver should transmit 150 kW (CW operation) RF power to the proton beam. The estimated RF losses on the power coupler outer conductor in standing wave mode operation are 46 W. To remove these heat loads, a full scale copper coil heat exchanger brazed around the outer conductor was designed and tested using supercritical helium at T = 6 K as a coolant. Our main objective was to minimise the heat loads to cold extremity of SRF cavity maintained at 2 K or 4.2 K. A dedicated test facility named SUPERCRYLOOP was developed and successfully operated in order to measure the performance of the cold heat exchanger. The test cell used reproduces the realistic thermal boundary conditions of the power coupler mounted on the cavity in the cryomodule. After a short introduction, a brief discussion about the problem of power coupler cooling systems in different machines is made. After that, we describe the experimental set-up and test apparatus. Then, a heat exchanger thermal model will be developed with FEM code COSMOS/M to estimate the different heat transfer coefficients by comparison between numerical simulation results and experimental data in order to validate the design. Finally, thermo-hydraulic behavior of supercritical helium has been investigated as function of different parameters (inlet pressure, flow rate, heat loads).

  7. Coupling Characteristics of Fused Optical Fiber Coupler Formed with Single-Mode Fiber and Photonic Crystal Fiber Having Air Hole Collapsed Taper

    Directory of Open Access Journals (Sweden)

    Hirohisa Yokota

    2016-01-01

    Full Text Available Fused coupler forming with a single-mode fiber (SMF and a photonic crystal fiber (PCF is one of the solutions for optical coupling from a light source to a PCF. In this paper, we presented coupling characteristics of a fused fiber coupler formed with an ordinary SMF and a PCF having air hole collapsed taper. A prototype of SMF-PCF coupler with air hole collapsed taper was fabricated using CO2 laser irradiation. The coupling efficiency from SMF to PCF was −6.2 dB at 1554 nm wavelength in the fabricated coupler. The structure of the SMF-PCF coupler to obtain high coupling efficiency was theoretically clarified by beam propagation analysis using an equivalent model of the coupler with simplification. It was clarified that appropriately choosing the prestretched or etched SMF diameter and the length of air hole collapsed region was effective to obtain high coupling efficiency that was a result of high extinction ratio at cross port and low excess loss. We also demonstrated that the diameter of prestretched SMF to obtain high coupling efficiency was insensitive to the air hole diameter ratio to pitch of the PCF in the air hole collapsed SMF-PCF coupler.

  8. Novel gratings for next-generation instruments of astronomical observations

    Science.gov (United States)

    Ebizuka, N.; Okamoto, T.; Takeda, M.; Hosobata, T.; Yamagata, Y.; Sasaki, M.; Uomoto, M.; Shimatsu, T.; Sato, S.; Hashimoto, N.; Tanaka, I.; Hattori, T.; Ozaki, S.; Aoki, W.

    2017-05-01

    We will introduce current status of development of a birefringence volume phase holographic (B-VPH) grating, volume binary (VB) grating and reflector facet transmission (RFT) grating developing as the novel dispersive optical element for astronomical instruments for the 8.2m Subaru Telescope, for next generation 30 m class huge ground-based telescopes and for next generation large space-bone telescopes. We will also introduce a hybrid grism developed for MOIRCS (Multi-Object InfraRed Camera and Spectrograph) of the Subaru Telescope and a quasi-Bragg (QB) immersion grating. Test fabrication of B-VPH gratings with a liquid crystal (LC) of UV curable and normal LCs or a resin of visible light curable are performed. We successfully fabricated VB gratings of silicon as a mold with ridges of a high aspect ratio by means of the cycle etching process, oxidation and removal of silicon oxide. The RFT grating which is a surface-relief (SR) transmission grating with sawtooth shaped ridges of an acute vertex angle. The hybrid grism, as a prototype of the RFT grating, combines a high-index prism and SR transmission grating with sawtooth shape ridges of an acute vertex angle. The mold of the SR grating for the hybrid grism on to a work of Ni-P alloy of non-electrolysic plating successfully fabricated by using our ultra-precision machine and a single-crystal diamond bite. The QB immersion grating was fabricated by a combination of an inclined QB grating, Littrow prism and surface reflection mirror.

  9. Electromagnetically induced grating with Rydberg atoms

    Science.gov (United States)

    Asghar, Sobia; Ziauddin, Qamar, Shahid; Qamar, Sajid

    2016-09-01

    We present a scheme to realize electromagnetically induced grating in an ensemble of strongly interacting Rydberg atoms, which act as superatoms due to the dipole blockade mechanism. The ensemble of three-level cold Rydberg-dressed (87Rb) atoms follows a cascade configuration where a strong standing-wave control field and a weak probe pulse are employed. The diffraction intensity is influenced by the strength of the probe intensity, the control field strength, and the van der Waals (vdW) interaction. It is noticed that relatively large first-order diffraction can be obtained for low-input intensity with a small vdW shift and a strong control field. The scheme can be considered as an amicable solution to realize the atomic grating at the microscopic level, which can provide background- and dark-current-free diffraction.

  10. Stationary Light Pulses without Bragg Gratings

    CERN Document Server

    Lin, Yen-Wei; Peters, Thorsten; Liao, Wen-Te; Cho, Hung-Wen; Guan, Pei-Chen; Yu, Ite A

    2008-01-01

    The underlying mechanism of the stationary light pulse (SLP) was identified as a band gap being created by a Bragg grating formed by two counter-propagating coupling fields of similar wavelength. Here we present a more general view of the formation of SLPs, namely several balanced four-wave mixing processes sharing the same ground-state coherence. Utilizing this new concept we report the first experimental observation of a bichromatic SLP at wavelengths for which no Bragg grating can be established. We also demonstrate the production of a SLP directly from a propagating light pulse without prior storage. Being easily controlled externally makes SLPs a very versatile tool for low-light-level nonlinear optics and quantum information manipulation.

  11. 3D measurement using circular gratings

    Science.gov (United States)

    Harding, Kevin

    2013-09-01

    3D measurement using methods of structured light are well known in the industry. Most such systems use some variation of straight lines, either as simple lines or with some form of encoding. This geometry assumes the lines will be projected from one side and viewed from another to generate the profile information. But what about applications where a wide triangulation angle may not be practical, particularly at longer standoff distances. This paper explores the use of circular grating patterns projected from a center point to achieve 3D information. Originally suggested by John Caulfield around 1990, the method had some interesting potential, particularly if combined with alternate means of measurement from traditional triangulation including depth from focus methods. The possible advantages of a central reference point in the projected pattern may offer some different capabilities not as easily attained with a linear grating pattern. This paper will explore the pros and cons of the method and present some examples of possible applications.

  12. 130-nm tunable grating-mirror VCSEL

    DEFF Research Database (Denmark)

    Chung, Il-Sug; Mørk, Jesper

    2014-01-01

    We have reported that a combination of the high-index-contrast grating (HCG) mirror as movable mirror and the extended cavity configuration with an antireflection layer can provide a tuning wavelength range of 100 nm for tunable VCSELs. Here, we report that using the air-coupled cavity configurat......We have reported that a combination of the high-index-contrast grating (HCG) mirror as movable mirror and the extended cavity configuration with an antireflection layer can provide a tuning wavelength range of 100 nm for tunable VCSELs. Here, we report that using the air-coupled cavity...... configuration instead of the extended cavity configuration can bring 130-nm tuning range around 1330-nm wavelength. The air-coupled cavity is known to reduce the quantum confinement factor in VCSELs, increasing threshold. In our air-coupled cavity HCG VCSEL case, the very short power penetration length...

  13. Strong Optical Confinement between Flat Dielectric Gratings

    CERN Document Server

    Li, Jingjing; Fiorentino, Marco; Beausoleil, Raymond G

    2011-01-01

    We present a novel type of optical micro-cavity based on a Fabry-Perot resonance between parallel high contrast gratings with non-periodic patterns. Tight lateral confinement is obtained via the phase front distortion properties of these gratings. In such cavities, energy stored in the optical field resides primarily in free space, therefore is readily accessible to particles (atoms, molecules, nanocrystals, etc.) for sensing, trapping, or spectroscopic applications. We describe the physics of these resonators, and propose a design method based on stochastic optimization. We present numerical simulations of two and three dimensional cavities that have diffraction-limited mode volumes with quality factors in the range of $10^4$--$10^6$. The cavity has a purely planar geometry and can be fabricated in silicon for near-infrared applications using standard CMOS processes. These ideas can be extended to the visible domain using commonly available III-V materials.

  14. Optical Properties of Topological Insulator Bragg Gratings

    CERN Document Server

    Crosse, J A

    2015-01-01

    Using the transfer matrix formalism, we study the transmission properties of a Bragg grating constructed from a layered axionic material. Such a material can be realized by a topological insulator subject to a time-symmetry breaking perturbation, such as an external magnetic field or surface magnetic impurities. Whilst the reflective properties of the structure are only negligibly changed by the presence of the axionic material, the grating induces Faraday and Kerr rotations in the transmitted and reflected light, respectively. These rotations are proportional to the number of layers and the strength of the time-symmetry breaking perturbation. In areas of low reflectivity the rotation angle of TE polarization decreases with increasing incidence angle while the TM polarization increases with increasing incidence angle with the converse occurring in areas of high reflectivity. The formalism and results will be useful in the development of optical and photonic devices based on topological insulators, devices whi...

  15. High reflection mirrors for pulse compression gratings.

    Science.gov (United States)

    Palmier, S; Neauport, J; Baclet, N; Lavastre, E; Dupuy, G

    2009-10-26

    We report an experimental investigation of high reflection mirrors used to fabricate gratings for pulse compression application at the wavelength of 1.053microm. Two kinds of mirrors are studied: the mixed Metal MultiLayer Dielectric (MMLD) mirrors which combine a gold metal layer with some e-beam evaporated dielectric bilayers on the top and the standard e-beam evaporated MultiLayer Dielectric (MLD) mirrors. Various samples were manufactured, damage tested at a pulse duration of 500fs. Damage sites were subsequently observed by means of Nomarski microscopy and white light interferometer microscopy. The comparison of the results evidences that if MMLD design can offer damage performances rather similar to MLD design, it also exhibits lower stresses; being thus an optimal mirror substrate for a pulse compression grating operating under vacuum.

  16. Straw combustion on slow-moving grates

    DEFF Research Database (Denmark)

    Kær, Søren Knudsen

    2005-01-01

    Combustion of straw in grate-based boilers is often associated with high emission levels and relatively poor fuel burnout. A numerical grate combustion model was developed to assist in improving the combustion performance of these boilers. The model is based on a one-dimensional ‘‘walking......-column’’ approach and includes the energy equations for both the fuel and the gas accounting for heat transfer between the two phases. The model gives important insight into the combustion process and provides inlet conditions for a computational fluid dynamics analysis of the freeboard. The model predictions...... indicate the existence of two distinct combustion modes. Combustion air temperature and mass flow-rate are the two parameters determining the mode. There is a significant difference in reaction rates (ignition velocity) and temperature levels between the two modes. Model predictions were compared...

  17. Robust topology design of periodic grating surfaces

    DEFF Research Database (Denmark)

    Friis, Kasper Storgaard; Sigmund, Ole

    2012-01-01

    Modern nanoscale manufacturing techniques allow for a high degree of flexibility in designing surface microstructures and nanostructures. Injection molding of nanosized features allows for mass production of plastic components with a tailored nanostructure producing specific optical effects...... depending on the purpose. This work details the use of topology optimization for designing periodic polymer grating surfaces with complex optical properties. A method based on robust topology optimization is formulated for designing the nanostructure of plastic surfaces with extreme reflection...

  18. Theoretical and measured performance of diffraction gratings

    Energy Technology Data Exchange (ETDEWEB)

    Bowler, M.A. E-mail: m.bowler@dl.ac.uk; Finetti, P.; Holland, D.M.P.; Humphrey, I.; Quinn, F.M.; Roper, M.D

    2001-07-21

    At the SRS at Daresbury Laboratory, we are undertaking a programme comparing the results from efficiency calculations of diffraction gratings, mainly using the GRADIF code of Neviere, with measured efficiencies. The deviations from the predicted performance are larger for higher orders than for first order. Higher order contamination is important in determining the usability of the beamline for certain types of experiments, particularly at energies below 100 eV.

  19. Theoretical and measured performance of diffraction gratings

    CERN Document Server

    Bowler, M A; Holland, D M P; Humphrey, I; Quinn, F M; Röper, M D

    2001-01-01

    At the SRS at Daresbury Laboratory, we are undertaking a programme comparing the results from efficiency calculations of diffraction gratings, mainly using the GRADIF code of Neviere, with measured efficiencies. The deviations from the predicted performance are larger for higher orders than for first order. Higher order contamination is important in determining the usability of the beamline for certain types of experiments, particularly at energies below 100 eV.

  20. Detailed Investigations of Load Coefficients on Grates

    DEFF Research Database (Denmark)

    Andersen, Thomas Lykke; Rasmussen, Michael R.; Frigaard, Peter

    In this report is presented the results of model tests carried out at Dept. of Civil Engineering, aalborg University (AAU) on behalf of DONG Energy A/S and Vattenfall A/S, Denmark. The objective of the tests was to investigate the load coefficient on different grates and a solid plate for designi...... offshore windmill access platforms against run-up generated forces with special attention to the influence of air entrainment and the angle of attack....

  1. Characteristic calculation of directional coupler for accelerator high-power feeders

    CERN Document Server

    Egorov, M A; Kaminsky, V I; Sobenin, N P; Zavadtsev, A A

    2001-01-01

    The calculation results of directional couplers with connection via the waveguide common narrow wall a coupling factor of 3.0 decibels,directivity no less than 20 decibels,adjustment of coupling factor at +- 1 decibels are presented. The adjustment is carried out with the help of cylindrical plungers, moving inside of waveguides on the part of broad walls in the location of the connection slot,and prismatic plungers,moving in rectangular waveguides connected to narrow walls opposite to a slot of connection. The device as a magic tee with movable throttle pistons in E- and H-plane arms permitting to match any load is designed too. The calculations are executed for devices operating at frequencies of 2.797 and 1.3 GHz.

  2. Analyzing the effects of post couplers in DTL tuning by the equivalent circuit model

    CERN Document Server

    Jia, Xiaoyu

    2013-01-01

    Stabilization of the accelerating field in Drift Tube Linac(DTL) is obtained by inserting Post Couplers(PCs).On the basis of the circuit model equivalent for the DTL with and without asymmetrical PCs, stabilization is deduced quantitatively: let $\\delta \\omega/\\omega_0$ be the relative frequency error, then we discover that the sensitivity of field to perturbation is proportional to $\\sqrt{\\delta \\omega / \\omega_0}$ without PCs and to $\\delta \\omega/\\omega_0$ with PCs. Then we adapt the circuit model of symmetrical PCs for the case of asymmetrical PCs. The circuit model shows how the slope of field distribution is changed by rotating the asymmetrical PCs and illustrates that the asymmetrical PCs have the same effect as the symmetrical ones in stabilization.

  3. Analyzing the effects of post couplers in DTL tuning by the equivalent circuit model

    Science.gov (United States)

    Jia, Xiao-Yu; Zheng, Shu-Xin

    2013-12-01

    Stabilization of the accelerating field in Drift Tube Linac(DTL) is obtained by inserting Post Couplers(PCs). On the basis of the equivalent circuit model for the DTL with and without asymmetrical PCs, stabilization is deduced quantitatively: we let δω/ω0 be the relative frequency error, then we discover that the sensitivity of field to perturbation is proportional to without PCs and to δω/ω0 with PCs. Then we adapt the circuit model of symmetrical PCs for the case of asymmetrical PCs. The circuit model shows how the slope of field distribution is changed by rotating the asymmetrical PCs and illustrates that the asymmetrical PCs have the same effect as the symmetrical ones in stabilization.

  4. Ultrasensitive optical microfiber coupler based sensors operating near the turning point of effective group index difference

    Science.gov (United States)

    Li, Kaiwei; Zhang, Ting; Liu, Guigen; Zhang, Nan; Zhang, Mengying; Wei, Lei

    2016-09-01

    We propose and study an optical microfiber coupler (OMC) sensor working near the turning point of effective group index difference between the even supermode and odd supermode to achieve high refractive index (RI) sensitivity. Theoretical calculations reveal that infinite sensitivity can be obtained when the measured RI is close to the turning point value. This diameter-dependent turning point corresponds to the condition that the effective group index difference equals zero. To validate our proposed sensing mechanism, we experimentally demonstrate an ultrahigh sensitivity of 39541.7 nm/RIU at a low ambient RI of 1.3334 based on an OMC with the diameter of 1.4 μm. An even higher sensitivity can be achieved by carrying out the measurements at RI closer to the turning point. The resulting ultrasensitive RI sensing platform offers a substantial impact on a variety of applications from high performance trace analyte detection to small molecule sensing.

  5. Optimization of optical filter using triple coupler ring resonators structure based on polyimide substrate

    Science.gov (United States)

    Mahmudin, D.; Estu, T. T.; Fathnan, A. A.; Maulana, Y. Y.; Daud, P.; Sugandhi, G.; Wijayanto, Y. N.

    2016-11-01

    Optical filter is very important components in WDM network. MRR is a basic structure to design the optical filter because of easy to design for improving its performance. This paper discusses an innovative structure of the MRR, which is Triple Coupler Ring Resonators (TCRR) for optical filter applications. Values of width between bus and ring and values of radius of the ring in the structure TCRR were analyzed and optimized for several variations for obtaining coupling coefficient values. Therefore, wide Free Spectral Range (FSR) and high crosstalk suppression bandwidth can be obtained. As results, at the optimized width of gap of 100 nm and the optimized radiation of 8 μm, FSR of 2.85 THz and crosstalk suppression bandwidth of 60 GHz were achieved. Based on the results, this structure can be used for filtering optical signals in optical fiber communication.

  6. On the Bandgap quantum coupler and the harmonic oscillator interacting with a reservoir

    CERN Document Server

    Quijas, P C G

    2007-01-01

    In order to be able to study dissipation, the interaction between a single system and their environment was introduced in quantum mechanics. Master and quantum Langeving equations was derived and, also, decoherence was studied using this approach. One of the most used model in this field of research is a single harmonic oscillator interacting with an infinite number of harmonic oscillators. In this work we analytically solve, with the evolution operator method, the Schrodinger equation for this model in the case of resonance. Also we address a different aspect of the quantum computing with linear optics. That is, we propose the linear bandgap quantum coupler, in the cases N=2 and N=3, to generate a new phase operator $U_{dp}^{\\pi} $ working on the two and three qubits basis like an alternative realization of a quantum phase gate.

  7. Magnetotransport in a dual waveguide coupled by a finite barrier: Energy filter and directional coupler

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    We propose in this paper that a dual waveguide coupled by a finite barrier be able to serve as an energy filter under a perpendicular magnetic field. In the waveguide direction, the conductance exhibits a periodic square-wave pattern in which the miniband is controlled by the magnetic and potential modulation. The electrons with energies in the miniband can completely transfer along one waveguide while the other electrons undergo filtration. Compared with the coupled waveguide without magnetic modulation, the structure under magnetic field is found to be a good directional coupler. By adjusting the potential barrier and magnetic field, the electrons input from one port of waveguide can transfer to any other ports.

  8. Optical solitons in PT-symmetric nonlinear couplers with gain and loss

    Science.gov (United States)

    Alexeeva, N. V.; Barashenkov, I. V.; Sukhorukov, Andrey A.; Kivshar, Yuri S.

    2012-06-01

    We study spatial and temporal solitons in the PT symmetric coupler with gain in one waveguide and loss in the other. Stability properties of the high- and low-frequency solitons are found to be completely determined by a single combination of the soliton's amplitude and the gain-loss coefficient of the waveguides. The unstable perturbations of the high-frequency soliton break the symmetry between its active and lossy components which results in a blowup of the soliton or a formation of a long-lived breather state. The unstable perturbations of the low-frequency soliton separate its two components in space, thereby blocking the power drainage of the active component and cutting the power supply to the lossy one. Eventually this also leads to the blowup or breathing.

  9. Optical solitons in $\\mathcal{PT}$-symmetric nonlinear couplers with gain and loss

    CERN Document Server

    Alexeeva, N V; Sukhorukov, Andrey A; Kivshar, Yuri S

    2012-01-01

    We study spatial and temporal solitons in the $\\mathcal{PT}$ symmetric coupler with gain in one waveguide and loss in the other. Stability properties of the high- and low-frequency solitons are found to be completely determined by a single combination of the soliton's amplitude and the gain/loss coefficient of the waveguides. The unstable perturbations of the high-frequency soliton break the symmetry between its active and lossy components which results in a blowup of the soliton or a formation of a long-lived breather state. The unstable perturbations of the low-frequency soliton separate its two components in space blocking the power drainage of the active component and cutting the power supply to the lossy one. Eventually this also leads to the blowup or breathing.

  10. A gold hybrid structure as optical coupler for quantum well infrared photodetector

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Jiayi; Li, Qian; Jing, Youliang [National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 500 Yu Tian Road, Shanghai 200083 (China); Chen, Xiaoshuang, E-mail: xschen@mail.sitp.ac.cn; Li, Zhifeng; Li, Ning; Lu, Wei [National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 500 Yu Tian Road, Shanghai 200083 (China); Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2014-08-28

    A hybrid structure consisting of a square lattice of gold disk arrays and an overlaying gold film is proposed as an optical coupler for a backside-illuminated quantum well infrared photodetector (QWIP). Finite difference time-domain method is used to numerically simulate the reflection spectra and the field distributions of the hybrid structure combined with the QWIP device. The results show that the electric field component perpendicular to the quantum well is strongly enhanced when the plasmonic resonant wavelength of the hybrid structure coincides with the response one of the quantum well infrared photodetector regardless of the polarization of the incident light. The effect of the diameter and thickness of an individual gold disk on the resonant wavelength is also investigated, which indicates that the localized surface plasmon also plays a role in the light coupling with the hybrid structure. The coupling efficiency can exceed 50 if the structural parameters of the gold disk arrays are well optimized.

  11. PT-symmetric coupler with a coupling defect: soliton interaction with exceptional point

    CERN Document Server

    Bludov, Yuli V; Huang, Guoxiang; Konotop, Vladimir V

    2014-01-01

    We study interaction of a soliton in a parity-time (PT) symmetric coupler which has local perturbation of the coupling constant. Such a defect does not change the PT-symmetry of the system, but locally can achieve the exceptional point. We found that the symmetric solitons after interaction with the defect either transform into breathers or blow up. The dynamics of anti-symmetric solitons is more complex, showing domains of successive broadening of the beam and of the beam splitting in two outwards propagating solitons, in addition to the single breather generation and blow up. All the effects are preserved when the coupling strength in the center of the defect deviates from the exceptional point. If the coupling is strong enough the only observable outcome of the soliton-defect interaction is the generation of the breather.

  12. DESIGN OF HYBRID COUPLER CONNECTED SQUARE ARRAY PATCH ANTENNA FOR Wi-Fi APPLICATIONS

    Directory of Open Access Journals (Sweden)

    A. Sahaya Anselin Nisha

    2012-01-01

    Full Text Available Microstrip patch antennas being popular because of light weight, low volume, thin profile configuration which can be made conformal. Wireless communication systems applications circular polarization antenna is placing vital role. In this study we introduce a new technique to produce circular polarization. Hybrid coupler is directly connected to microstrip antenna to get circular polarization. Also gain is further increased by introducing antenna array technique. Each square in array having length of 4.6mm patch is having thickness of 0.381mm and the dielectric material used FR4. The designed antenna having high gain of 6.26dB and directivity of 5.11dB at the resonant frequency of 3.7GHz. Simulation results shows that the designed antenna characteristic is suitable for Wi-Fi applications.

  13. Floquet control of the gain and loss in a PT-symmetric optical coupler

    Science.gov (United States)

    Wu, Yi; Zhu, Bo; Hu, Shu-Fang; Zhou, Zheng; Zhong, Hong-Hua

    2017-02-01

    Controlling the balanced gain and loss in a PT-symmetric system is a rather challenging task. Utilizing Floquet theory, we explore the constructive role of periodic modulation in controlling the gain and loss of a PT-symmetric optical coupler. It is found that the gain and loss of the system can be manipulated by applying a periodic modulation. Further, such an original non-Hermitian system can even be modulated into an effective Hermitian system derived by the high-frequency Floquet method. Therefore, compared with other PT symmetry control schemes, our protocol can modulate the unbroken PT-symmetric range to a wider parameter region. Our results provide a promising approach for controlling the gain and loss of a realistic system.

  14. High repetition rate Q-switched radially polarized laser with a graphene-based output coupler

    Energy Technology Data Exchange (ETDEWEB)

    Li, Lifei; Jin, Chenjie; Qi, Mei; Chen, Xiaoming; Ren, Zhaoyu, E-mail: zhengxl@nwu.edu.cn, E-mail: rzy@nwu.edu.cn [National Key Laboratory of Photoelectric Technology and Functional Materials (Culture Base), and Institute of Photonics and Photon-Technology, Northwest University, Xi' an 710069 (China); Zheng, Xinliang, E-mail: zhengxl@nwu.edu.cn, E-mail: rzy@nwu.edu.cn [Department of Physics, Northwest University, Xi' an 710069 (China); Bai, Jintao [National Key Laboratory of Photoelectric Technology and Functional Materials (Culture Base), and Institute of Photonics and Photon-Technology, Northwest University, Xi' an 710069 (China); Department of Physics, Northwest University, Xi' an 710069 (China); Sun, Zhipei [Department of Micro- and Nanosciences, Aalto University, P.O. Box 13500, FI-00076 Aalto (Finland)

    2014-12-01

    We demonstrate a Q-switched radially polarized all-solid-state laser by transferring a graphene film directly onto an output coupler. The laser generates Q-switched radially polarized beam (QRPB) with a pulse width of 192 ns and 2.7 W average output power. The corresponding single pulse energy is up to 16.2 μJ with a high repetition rate of 167 kHz. The M{sup 2} factor and the polarization purity are ∼2.1 and 96%, respectively. Our QRPB source is a simple and low-cost source for a variety of applications, such as industrial material processing, optical trapping, and microscopy.

  15. Behavioral Modeling of a C-Band Ring Hybrid Coupler Using Artificial Neural Networks

    Directory of Open Access Journals (Sweden)

    E. Demircioglu

    2010-12-01

    Full Text Available Artificial Neural Networks (ANNs gained importance on the RF microwave (MW design area and behavioral modeling of MW components in the past few decades. This paper presents a cost effective neural network (NN approach to overcome design, modeling and optimization problems of an 180deg ring hybrid coupler operating in C-Band. The proposed NN model is trained by data sets obtained from electromagnetic (EM simulators and neural test results are compared with simulator findings to determine the network accuracy. Moreover, necessary trade-offs are applied to improve the networks’ performance. Finally correlation factors, which are defined as comparison criteria between EM-simulator and proposed neural models, are calculated for each trade-off case.

  16. Polarization splitter based on a three waveguide directional coupler using quantum mechanical analogies

    Science.gov (United States)

    Aashna, Pragati; Thyagarajan, K.

    2017-06-01

    We propose a novel waveguide polarization splitter based on the optical analogue of two-photon Rabi oscillations and stimulated Raman adiabatic passage in a three waveguide directional coupler. Both these processes are borrowed from three level quantum mechanical atomic systems, in which an intermediate level is used to transfer the population from one state to another without any population occupation in the intermediate level. To show the practical feasibility of the device, simulations have been carried out on waveguides in lithium niobate and we show that two orthogonal polarizations can be separated at the output using the proposed three waveguide structures. We also show that the proposed structure is robust against changes in phase mismatch parameters, as well as wavelength of operation.

  17. Broadband Dual Circularly Polarized Magnetoelectric Dipole Antenna Fed by a Miniaturized Six-Branch Hybrid Coupler

    Directory of Open Access Journals (Sweden)

    Changhong Zhang

    2016-01-01

    Full Text Available A broadband dual circularly polarized magnetoelectric dipole antenna (MEDA fed by a miniaturized six-branch hybrid coupler (SBHC is presented in this paper. First, a dual linearly polarized MEDA with a bandwidth of 73.3% is developed based on the previous design with a bandwidth of 52%. The SBHC, with a miniaturized size of 53%, is designed on a printed circuit board underneath the ground of the MEDA, which possesses an efficient bandwidth of 80.7% to generate the antenna for dual circular polarization. Measurement results show that the proposed dual circularly polarized MEDA achieves an impedance bandwidth of 84.5%, an axial-ratio bandwidth of 81.8%, and a nearly symmetrical, stable unidirectional radiation pattern with an average gain of 8 dBic over its impedance bandwidth.

  18. Influence of offset stem couplers in femoral revision knee arthroplasty: a radiographic study.

    Science.gov (United States)

    Brilhault, Jean M; Ries, Michael D

    2012-03-01

    We questioned whether the use of offset femoral stem would result in modifying the posterior femoral condylar offset (PFCO) in revision knee arthroplasty (RTKA). We measured both PFCO and stem alignment on lateral radiographs of two cohorts: 91 knees with straight stems and 35 knees with offset coupled stems. A higher PCOR was observed in knees with an offset stem compared to knees with straight stem. Knees with an offset stem had a better alignment within the intramedullary canal. Our conclusion is that the use of a modular offset coupler with femoral stem in RTKA compared to a modular straight stem both increases the posterior condylar offset and improves alignment of the stem within the intramedullary canal.

  19. An Easily Operating Polymer 1×4 Optical Waveguide Switch Matrix Based on Vertical Couplers

    Institute of Scientific and Technical Information of China (English)

    Kaixin Chen; Pak L Chu; Hau Ping Chan; Kin S. Chiang

    2007-01-01

    A three-dimensional (3D) polymer thermo-optic (TO) 1×4 waveguide switch matrix based on vertical couplers is demonstrated. It consists of four basic 3D switch units and because of its 3D structure, its construction is compact, only 9mm in length; moreover, the control logic of the entire switch is very simple, the light signal can be easily switched to any output port by operating only a single switch unit. The finished devices exhibit a switching extinction ratio greater than 21 dB for all of four output ports and the crosstalk between two adjacent output ports is lower than n for all switching units is about 50 mW.

  20. The Design of a Five-Cell Superconducting RF Module with a PBG Coupler Cell

    Energy Technology Data Exchange (ETDEWEB)

    Arsenyev, Sergey A [Los Alamos National Laboratory; Simakov, Evgenya I [Los Alamos National Laboratory

    2012-08-29

    We discuss the problem of incorporating a Photonic Band Gap (PBG) cell into a superconducting accelerating module of 5 cells designed for the operational frequency of 2.1 GHz. The reason for using a PBG cell is to provide a good accelerating mode confinement and good Higher Order Mode (HOM) suppression. PBG cell can potentially be used for placing HOM and fundamental mode couplers. However, because of the naturally higher ratio of the peak magnetic field to the accelerating field in the PBG cell, it should be designed to operate at a lower accelerating gradient than the other cells of the module. This ensures that the probability of quench in the PBG cell would be no higher than in other elliptical cells of the structure.

  1. High Power Tm3+-Doped Fiber Lasers Tuned by a Variable Reflective Output Coupler

    Directory of Open Access Journals (Sweden)

    Yulong Tang

    2008-01-01

    Full Text Available Wide wavelength tuning by a variable reflective output coupler is demonstrated in high-power double-clad Tm3+-doped silica fiber lasers diode-pumped at ∼790  nm. Varying the output coupling from 96% to 5%, the laser wavelength is tuned over a range of 106  nm from 1949 to 2055  nm. The output power exceeds 20  W over 90-nm range and the maximum output power is 32  W at 1949  nm for 51-W launched pump power, corresponding to a slope efficiency of ∼70%. Assisted with different fiber lengths, the tuning range is expanded to 240  nm from 1866 to 2107  nm with the output power larger than 10  W.

  2. A numerical method for determining the radial wave motion correction in plane wave couplers

    DEFF Research Database (Denmark)

    Cutanda Henriquez, Vicente; Barrera Figueroa, Salvador; Torras Rosell, Antoni

    2016-01-01

    solution is an analytical expression that estimates the difference between the ideal plane wave sound field and a more complex lossless sound field created by a non-planar movement of the microphone’s membranes. Alternatively, a correction may be calculated numerically by introducing a full model......Microphones are used for realising the unit of sound pressure level, the pascal (Pa). Electro-acoustic reciprocity is the preferred method for the absolute determination of the sensitivity. This method can be applied in different sound fields: uniform pressure, free field or diffuse field. Pressure...... calibration, carried out in plane wave couplers, is the most extended. Here plane wave propagation is assumed. While this assumption is valid at low and mid frequencies, it fails at higher frequencies because the membrane of the microphones is not moving uniformly, and there are viscous losses. An existing...

  3. Chalcogenide glass planar MIR couplers for future chip based Bracewell interferometers

    CERN Document Server

    Goldsmith, Harry-Dean Kenchington; Ireland, Michael; Ma, Pan; Tuthill, Peter; Eggleton, Ben; Lawrence, John S; Debbarma, Sukanta; Luther-Davies, Barry; Madden, Stephen J

    2016-01-01

    Photonic integrated circuits are established as the technique of choice for a number of astronomical processing functions due to their compactness, high level of integration, low losses, and stability. Temperature control, mechanical vibration and acoustic noise become controllable for such a device enabling much more complex processing than can realistically be considered with bulk optics. To date the benefits have mainly been at wavelengths around 1550 nm but in the important Mid-Infrared region, standard photonic chips absorb light strongly. Chalcogenide glasses are well known for their transparency to beyond 10000 nm, and the first results from coupler devices intended for use in an interferometric nuller for exoplanetary observation in the Mid-Infrared L band (3800-4200 nm) are presented here showing that suitable performance can be obtained both theoretically and experimentally for the first fabricated devices operating at 4000 nm.

  4. A subwavelength structured multimode interference coupler for the 3-4 micrometers mid-infrared band

    Science.gov (United States)

    Sánchez-Postigo, Alejandro; Wangüemert-Pérez, Juan Gonzalo; Halir, Robert; Ortega-Moñux, Alejandro; Alonso-Ramos, Carlos A.; Molina-Fernández, Íñigo; Soler Penadés, Jordi; Nedeljkovic, Milos; Mashanovich, Goran Z.; Cheben, Pavel

    2015-05-01

    The mid-infrared is attracting increasing attention since many molecules, including potentially hazardous gases such as methane and carbon dioxide, exhibit very specific absorption spectra in this wavelength region. Integrated silicon photonics circuits are envisioned to enable compact and low-cost measurement solutions for these molecules. Multimode interference couplers (MMIs) are basic building blocks for photonic circuits and a broad operational bandwidth is key if flexible operation is to be achieved, e.g. to detect different gases. Here we overcome the bandwidth limitations found in classical MMIs by segmenting the multimode region at a sub-wavelength pitch to engineer its refractive index and dispersion. We achieve less than 0:5 dB imbalance and excess loss in the complete 3 ̶ 4 µm wavelength range. The sub-wavelength MMI not only exhibits nearly threefold improvement in bandwidth, but is also about three times shorter than the conventional device.

  5. Tolerance study for the components of the probe-type and hook-type Higher Order Mode couplers for the HL-LHC 800 MHz harmonic system

    CERN Document Server

    Blanco, Esteban

    2016-01-01

    A superconducting 800 MHz second harmonic RF system is one of the considered options as a Landau damping mechanism for HiLumi LHC. The Higher Order Mode (HOM) coupler designs require tight manufacturing tolerances in order to operate at the design specifications. The project consists of defining the mechanical tolerances for the different components of both the probe-type and hook-type HOM coupler. With the use of electromagnetic field simulation software it is possible to identify the critical components of the HOM coupler and to quantify their respective tolerances. The obtained results are discussed in this paper.

  6. Grating Spectroscopes and How to Use Them

    CERN Document Server

    Harrison, Ken M

    2012-01-01

    Transmission grating spectroscopes look like simple filters and are designed to screw into place on the eyepiece tube of a telescope for visual use, or into a camera adapter for digicam or CCD imaging. They are relatively inexpensive and by far the easiest type of astronomical spectroscope to use, and so are the starting point for most beginners. Using the most popular commercially made filter gratings - from Rainbow Optics in the United States to Star Analyser in the United Kingdon - as examples, the book provides all the information needed to set up and use the grating to obtain stellar spectra. It also presents methods of analyzing the results. No heavy mathematics or formulas are involved, although a reasonable level of proficiency in using an astronomic telescope and, if relevant, imaging camera, is assumed. This book contains many practical hints and tips - something that is almost essential to success when starting out. It encourages new users to get quick results, and by following the worked examples,...

  7. Grating THz laser with optical pumping

    Science.gov (United States)

    Khoury, Jed; Haji-saeed, Bahareh; Woods, Charles; Kierstead, John

    2010-04-01

    In this paper, we present a design for a widely tunable solid-state optically and electrically pumped THz laser based on the Smith-Purcell free-electron laser. In the free-electron laser, an energetic electron beam pumps a metallic grating to generate surface plasmons. Our solid-state optically pumped design consists of a thin layer of dielectic, such as SiNx, sandwiched between a corrugated structure and a thin metal or semiconductor layer. The lower layer is for current streaming, and replaces the electron beam in the original design. The upper layer consists of one micro-grating for coupling the electromagnetic field in, another for coupling out, and a nano-grating for coupling with the current in the lower layer for electromagnetic field generation. The surface plasmon waves generated from the upper layer by an external electromagnetic field, and the lower layer by the applied current, are coupled. Emission enhancement occurs when the plasmonic waves in both layers are resonantly coupled.

  8. Composite cure monitoring with Bragg grating sensors

    Science.gov (United States)

    Slattery, Kerry T.; Corona-Bittick, Kelli; Dorr, Donald J.

    1998-03-01

    Residual stress is induced in fiber composite materials during the cure process because the thermal expansion coefficient of the fiber is generally much lower than that of the polymer matrix. The two materials are 'locked' together at the cure temperature. Then, as they cool, the matrix attempts to contract more than the fiber leading to tension in the matrix and compression in the fiber. This can lead to the formation of microcracks parallel to the fibers in thick composite piles or yarns. The magnitude of residual stress can be reduced by modifying the cure cycle; however, optimizing the cure cycle requires a complete understanding of the state of cure throughout the composite. This is a complex problem -- especially in thick composites. Pilot studies have been performed placing Bragg gratin sensors in glass fabric preforms and monitoring the response of the grating during resin infusion and cure. The typical response shows the initial thermal expansion of the Bragg grating, a rapid contraction of the grating as the resin gels, slower contraction during cure, and thermal contraction at the composite thermal expansion coefficient during cool down. This data is then sued with micromechanical models of the fiber/matrix interaction during cure to establish material parameters for cure simulation. Once verified, these cure simulation methods will be used to optimize tooling design and cure cycles in composite components.

  9. All-fiber mode selective couplers for mode-division-multiplexed optical transmission

    Science.gov (United States)

    Chang, Sun Hyok; Kim, Kwangjoon; Lee, Joon Ki

    2017-01-01

    All-fiber mode selective coupler (MSC) is comprised of a few mode fiber (FMF) and a single mode fiber (SMF), coupling the LP01 mode of the SMF to a specific higher-order mode (HOM) of the FMF. In order to achieve high coupling ratio and low insertion loss, phase-matching condition between the LP01 mode of SMF arm and the HOM of FMF arm should be satisfied. A polished-type MSC is made by getting their cores into intimate contact. Prism coupling with a polished coupler block can measure the effective refractive index of the mode accurately. We propose and demonstrate three kinds of allfiber mode multiplexer that is composed of consecutive MSCs. 4-mode multiplexer can multiplex 4 modes of LP01, LP11, LP21, and LP02 by cascading LP11, LP21, and LP02 MSCs. It is used for MDM transmission of three modes with 120 Gb/s DP-QPSK signals. In order to enhance the signal transmission performance by receiving degenerate LP modes simultaneously, a mode multiplexer to utilize two-fold degenerate LP11 modes is proposed. It is composed of two consecutive LP11 MSCs that allows the multiplexing of LP01 mode and two orthogonal LP11 modes. We demonstrates WDM transmission of 30 wavelength channels with 33.3 GHz spacing, each carrying 3 modes, over 560 km of FMF. 6- mode multiplexer can multiplex 6 modes of LP01, LP11a, LP11b, LP21a, LP21b, LP02 modes. We demonstrated WDM-MDM transmission with the all-fiber 6-mode multiplexer. In this paper, the manufacturing method and the recent advancements of the all-fiber mode multiplexer based on the MSCs are reviewed. Long-distance mode division multiplexing (MDM) optical signal transmissions with the all-fiber mode multiplexer are experimentally demonstrated.

  10. Measuring vibration by using fiber Bragg grating and demodulating it by blazed grating

    Institute of Scientific and Technical Information of China (English)

    Xiaojin Guo(郭晓金); Zongmin Yin(殷宗敏); Ning Song(宋宁)

    2004-01-01

    A method of measuring vibration by using fiber Bragg grating (FBG) and demodulating the spectrum by blazed grating is introduced. The sensor system is made of a simple supported beam with a FBG adhered to its upper surface. A blazed grating is used to demodulate the changing spectrum that is got from the sensor system, and a line charge-coupled device (CCD) is used to accept the diffraction spectrum.Through analyzing the number of the CCD's pixels, we can get the amplitude of vibration and the change of the temperature. The experimental results show that the vibration amplitude of the exciter matches the detected signal under the stable frequency. The temperature shift and vibration signal are also successfully separated.

  11. Towards freeform curved blazed gratings using diamond machining

    Science.gov (United States)

    Bourgenot, C.; Robertson, D. J.; Stelter, D.; Eikenberry, S.

    2016-07-01

    Concave blazed gratings greatly simplify the architecture of spectrographs by reducing the number of optical components. The production of these gratings using diamond-machining offers practically no limits in the design of the grating substrate shape, with the possibility of making large sag freeform surfaces unlike the alternative and traditional method of holography and ion etching. In this paper, we report on the technological challenges and progress in the making of these curved blazed gratings using an ultra-high precision 5 axes Moore-Nanotech machine. We describe their implementation in an integral field unit prototype called IGIS (Integrated Grating Imaging Spectrograph) where freeform curved gratings are used as pupil mirrors. The goal is to develop the technologies for the production of the next generation of low-cost, compact, high performance integral field unit spectrometers.

  12. Phasor analysis of binary diffraction gratings with different fill factors

    Energy Technology Data Exchange (ETDEWEB)

    MartInez, Antonio [Departamento de Ciencia de Materiales, Optica y TecnologIa Electronica, Universidad Miguel Hernandez, 03202 Elche (Spain); Sanchez-Lopez, Ma del Mar [Instituto de BioingenierIa y Departamento de Fisica y Arquitectura de Computadores, Universidad Miguel Hernandez, 03202 Elche (Spain); Moreno, Ignacio [Departamento de Ciencia de Materiales, Optica y TecnologIa Electronica, Universidad Miguel Hernandez, 03202 Elche (Spain)

    2007-09-11

    In this work, we present a simple analysis of binary diffraction gratings with different slit widths relative to the grating period. The analysis is based on a simple phasor technique directly derived from the Huygens principle. By introducing a slit phasor and a grating phasor, the intensity of the diffracted orders and the grating's resolving power can be easily obtained without applying the usual Fourier transform operations required for these calculations. The proposed phasor technique is mathematically equivalent to the Fourier transform calculation of the diffraction order amplitude, and it can be useful to explain binary diffraction gratings in a simple manner in introductory physics courses. This theoretical analysis is illustrated with experimental results using a liquid crystal device to display diffraction gratings with different fill factors.

  13. Simulation of Novel Tunable Nonlinear Chirped Fiber Bragg Grating

    Institute of Scientific and Technical Information of China (English)

    LIU Yu-min; YU Zhong-yuan; ZHANG Xiao-guang; YU Li; YANG Bo-jun

    2003-01-01

    A novel tunable chirped fiber Bragg grating technology is proposed and simulated numerically by Matlab. If we adhere a uniform fiber grating with super magnetostrictive film and expose them in a non-uniform magnetic field, the period of the grating can be changed with the strain imposed on it by the magnetostrictive effect .The chirped characteristics can be tuned by changing the magnetic filed which is very flexible in designing.

  14. Adaptive perfectly matched layer for Wood's anomalies in diffraction gratings

    CERN Document Server

    Vial, Benjamin; Nicolet, André; Commandré, Mireille; Tisserand, Stéphane

    2015-01-01

    We propose an Adaptive Perfectly Matched Layer (APML) to be used in diffraction grating modeling. With a properly tailored co-ordinate stretching depending both on the incident field and on grating parameters, the APML may efficiently absorb diffracted orders near grazing angles (the so-called Wood's anomalies). The new design is implemented in a finite element method (FEM) scheme and applied on a numerical example of a dielectric slit grating. Its performances are compared with classical PML with constant stretching coefficient.

  15. Refractometric sensors based on long period optical fiber gratings

    OpenAIRE

    2006-01-01

    In this work, results of the design of uniform and nonuniform longperiod gratings are presented, with a view to being used as refractometric sensors. We found an optimal combination of the longitudinal variation of the fiber refractive index and the grating period, which increases the sensor linearity in comparison with a uniform grating, without decreasing its average sensitivity within a range of the external refractive index from 1.41 to 1.44.

  16. Optical implementation of the Hopfield neural network with matrix gratings

    Science.gov (United States)

    Yeh, Sheng L.; Lo, Rong C.; Shi, Cha Y.

    2004-02-01

    We propose a new method for the optical implementation of the Hopfield neural network with a universal tool. The tool is a matrix grating constituted with a group of element gratings. The algorithms for designing a matrix grating are proposed, and a matrix grating is created to execute recognition experiments by use of the Hopfield neural network. The experimental results demonstrate that the proposed method performs well. The stability of the light efficiencies of different optical components used in optical networks is also considered.

  17. Effect of Effective Refractive Index of Grating in FBG Splitter

    Directory of Open Access Journals (Sweden)

    DINESH ARORA

    2011-09-01

    Full Text Available The Fiber Bragg Gratings have been used extensively in the communication industry. Fiber Bragg grating is written directly into the core of the optical fiber and it is quite an attractive technique for wavelength splitter since it provides high reflectivity at a certain wavelength, with negligible transmission losses for others, providing a wavelength-channel selection with low crosstalk between adjacent channels.In this paper we propose a Fiber Bragg Grating base splitter with alteration of effective refractive index of grating for Ethernet passive optical network. With the increase in the effective refractive index the reflectivity of grating is increased. We analysed the effect of effective refractive index on reflectivity of grating. In our work the Bragg wavelength has been fixed at 1550 nm,length of the grating as 10mm and with effective refractive index as 4.0 it has been found that the reflectivity of the grating or the effectiveness of the grating in extracting the wavelength is 92-93%.

  18. Modeling spatially localized photonic nanojets from phase diffraction gratings

    Energy Technology Data Exchange (ETDEWEB)

    Geints, Yu. E., E-mail: ygeints@iao.ru [V.E. Zuev Institute of Atmospheric Optics SB RAS (IAO SB RAS), 1, Academician Zuev Square, Tomsk 634055 (Russian Federation); Tomsk State University, 36, Lenina Avenue, Tomsk 634050 (Russian Federation); Zemlyanov, A. A. [V.E. Zuev Institute of Atmospheric Optics SB RAS (IAO SB RAS), 1, Academician Zuev Square, Tomsk 634055 (Russian Federation)

    2016-04-21

    We investigated numerically the specific spatially localized intense optical structure, a photonic nanojet (PNJ), formed in the near-field scattering of optical radiation at phase diffraction gratings. The finite-difference time-domain technique was employed to study the PNJ key parameters (length, width, focal distance, and intensity) produced by diffraction gratings with the saw-tooth, rectangle, and hemispheric line profiles. Our analysis showed that each type of diffraction gratings produces a photonic jet with unique characteristics. Based on the numerical calculations, we demonstrate that the PNJ could be manipulated in a wide range through the variation of period, duty cycle, and shape of diffraction grating rulings.

  19. Diffraction Gratings for High-Intensity Laser Applications

    Energy Technology Data Exchange (ETDEWEB)

    Britten, J

    2008-01-23

    The scattering of light into wavelength-dependent discrete directions (orders) by a device exhibiting a periodic modulation of a physical attribute on a spatial scale similar to the wavelength of light has been the subject of study for over 200 years. Such a device is called a diffraction grating. Practical applications of diffraction gratings, mainly for spectroscopy, have been around for over 100 years. The importance of diffraction gratings in spectroscopy for the measurement of myriad properties of matter can hardly be overestimated. Since the advent of coherent light sources (lasers) in the 1960's, applications of diffraction gratings in spectroscopy have further exploded. Lasers have opened a vast application space for gratings, and apace, gratings have enabled entirely new classes of laser systems. Excellent reviews of the history, fundamental properties, applications and manufacturing techniques of diffraction gratings up to the time of their publication can be found in the books by Hutley (1) and more recently Loewen and Popov (2). The limited scope of this chapter can hardly do justice to such a comprehensive subject, so the focus here will be narrowly limited to characteristics required for gratings suitable for high-power laser applications, and methods to fabricate them. A particular area of emphasis will be on maximally-efficient large-aperture gratings for short-pulse laser generation.

  20. Improved layer peeling algorithm for strongly reflecting fiber gratings

    Institute of Scientific and Technical Information of China (English)

    Liqun Huang; Weiping Huang; Jinkuan Wang; Guang Yang

    2006-01-01

    @@ An improved algorithm based on the layer peeling (LP) method is proposed and demonstrated.The new method is shown to be effective for mitigating the impact of numerical errors on reconstruction of coupling function for strongly reflecting Bragg gratings.As examples,a flat-top dispersion-free fiber grating and a fiber-grating dispersion compensator are designed by the improved LP method.For a chirp grating,more accurate results are demonstrated in comparison with those obtained by the integral layer peeling (ILP) method.