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Sample records for cw power coupler

  1. Study of thermal interaction between a 150 kW CW power coupler and a superconducting 704 MHz elliptical cavity

    Energy Technology Data Exchange (ETDEWEB)

    Souli, M. [Institut de Physique Nucleaire d' Orsay, CNRS/IN2P3, Orsay (France)]. E-mail: souli@ipno.in2p3.fr; Fouaidy, M. [Institut de Physique Nucleaire d' Orsay, CNRS/IN2P3, Orsay (France); Saugnac, H. [Institut de Physique Nucleaire d' Orsay, CNRS/IN2P3, Orsay (France); Szott, P. [Institut de Physique Nucleaire d' Orsay, CNRS/IN2P3, Orsay (France); Gandolfo, N. [Institut de Physique Nucleaire d' Orsay, CNRS/IN2P3, Orsay (France); Bousson, S. [Institut de Physique Nucleaire d' Orsay, CNRS/IN2P3, Orsay (France); Braud, D. [CEA Saclay, DSM/DAPNIA/SACM, 91191 Gif sur Yvette (France); Charrier, J.P. [CEA Saclay, DSM/DAPNIA/SACM, 91191 Gif sur Yvette (France); Roudier, D. [CEA Saclay, DSM/DAPNIA/SACM, 91191 Gif sur Yvette (France); Sahuquet, P. [CEA Saclay, DSM/DAPNIA/SACM, 91191 Gif sur Yvette (France); Visentin, B. [CEA Saclay, DSM/DAPNIA/SACM, 91191 Gif sur Yvette (France)

    2006-07-15

    The power coupler needed for {beta} = 0.65 SRF elliptical cavities dedicated to the driver of XADS (eXperimental Accelerator Driven System) should transmit a CW RF power of 150 kW to a 10 mA proton beam. The estimated average values of the RF losses in the coupler are 130 W (respectively 46 W) for the inner (respectively outer) conductor in SW mode. Due to such high values of the RF losses, it is necessary to very carefully design and optimize the cooling circuits of the coupler in order to efficiently remove the generated heat and to reduce the thermal load to the cavity operating at T = 2 K. An experiment simulating the thermal interaction between the power coupler and a 704 MHz SRF five cells cavity was performed in the CRYHOLAB test facility in order to determine the critical heat load that can be sustained by the cavity without degradation of its RF performance. Experimental data are compared to numerical simulation results obtained with the Finite Element Method code COSMOS/M. These data allow us also to perform in situ measurements of the thermal parameters needed in the thermal model of the coupler (thermal conductivity, thermal contact resistance). These data are used to validate numerical simulations.

  2. 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).

  3. CW all optical self switching in nonlinear chalcogenide nano plasmonic directional coupler

    Science.gov (United States)

    Motamed-Jahromi, Leila; Hatami, Mohsen

    2018-04-01

    In this paper we obtain the coupling coefficient of plasmonic directional coupler (PDC) made up of two parallel monolayer waveguides filled with high nonlinear chalcogenide material for TM mode in continues wave (CW) regime. In addition, we assume each waveguides acts as a perturbation to other waveguide. Four nonlinear-coupled equations are derived. Transfer distances are numerically calculated and used for deriving length of all optical switch. The length of designed switch is in the range of 10-1000 μm, and the switching power is in the range of 1-100 W/m. Obtained values are suitable for designing all optical elements in the integrated optical circuits.

  4. Wireless power transfer magnetic couplers

    Science.gov (United States)

    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. Thermal-Mechanical Study of 3.9 GHz CW Coupler and Cavity for LCLS-II Project

    Energy Technology Data Exchange (ETDEWEB)

    Gonin, Ivan [Fermilab; Harms, Elvin [Fermilab; Khabiboulline, Timergali [Fermilab; Solyak, Nikolay [Fermilab; Yakovlev, Vyacheslav [Fermilab

    2017-05-01

    Third harmonic system was originally developed by Fermilab for FLASH facility at DESY and then was adopted and modified by INFN for the XFEL project [1-3]. In contrast to XFEL project, all cryomodules in LCLS-II project will operate in CW regime with higher RF average power for 1.3 GHz and 3.9 GHz cavities and couplers. Design of the cavity and fundamental power coupler has been modified to satisfy LCLS-II requirements. In this paper we discuss the results of COMSOL thermal and mechanical analysis of the 3.9 GHz coupler and cavity to verify proposed modifica-tion of the design. For the dressed cavity we present simulations of Lorentz force detuning, helium pressure sensitivity df/dP and major mechanical resonances.

  6. Fundamental Power Couplers for Superconducting Cavities

    International Nuclear Information System (INIS)

    Isidoro E. Campisi

    2001-01-01

    Fundamental power couplers (FPC's) for superconducting cavities must meet very strict requirements to perform at high power levels (hundreds of kilowatts) and in a variety of conditions (CS, pulsed, travelling wave, standing wave) without adversely affecting the performance of the cavities they are powering. Producing good coupler designs and achieving operational performances in accelerator environments are challenging tasks that have traditionally involved large resources from many laboratories. The designs involve state-of-the-art activities in RF, cryogenic and mechanical engineering, materials science, vacuum technology, and electromagnetic field modeling. Handling, assembly and conditioning procedures have been developed to achieve ever-increasing power levels and more reliable operation. In this paper, the technical issues associated with the design, construction, assembly, processing, and operation of FPC's will be reviewed, together with the progress in FPC activities in several laboratories during the past few years

  7. High-power tests of a single-cell copper accelerating cavity driven by two input couplers

    International Nuclear Information System (INIS)

    Horan, D.; Bromberek, D.; Meyer, D.; Waldschmidt, G.

    2008-01-01

    High-power tests were conducted on a 350-MHz, single-cell copper accelerating cavity driven simultaneously by two H-loop input couplers for the purpose of determining the reliability, performance, and power-handling capability of the cavity and related components, which have routinely operated at 100-kW power levels. The test was carried out utilizing the APS 350-MHz RF Test Stand, which was modified to split the input rf power into two frac12-power feeds, each supplying power to a separate H-loop coupler on the cavity. Electromagnetic simulations of the two-coupler feed system were used to determine coupler match, peak cavity fields, and the effect of phasing errors between the coupler feed lines. The test was conducted up to a maximum total rf input power of 164-kW CW. Test apparatus details and performance data will be presented.

  8. Development of the SCRF Power Coupler for the APT Accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Schmierer, E.N.; Lujan, R.E.; Rusnak, B.; Smith, B.; Haynes, W.B.; Gautier, C.; Waynert, J.A.; Krawczyk, F.; Gioia, J.

    1999-03-01

    The team responsible for the design of the Accelerator Production of Tritium (APT) superconducting (SC) radio frequency (RF) power coupler has developed two 700-MHz, helium gas-cooled power couplers. One has a fixed inner conductor and the other has an adjustable inner conductor (gamma prototype and alpha prototype). The power couplers will be performance tested in the near future. This paper discusses the mechanical design and fabrication techniques employed in the development of each power coupler. This includes material selection, copper coating, assembly sequences, and metal joining procedures, as well as the engineering analyses performed to determine the dynamic response of the inner conductors due to environmental excitations. A bellows is used in both prototype inner conductors in the area near the ceramic RF window, to compensate for thermal expansion and mechanical tolerance build-up. In addition, a bellows is used near the tip of the inner conductor of the alpha prototype for running the power coupler after it is installed on the accelerator. Extensive analytical work has been performed to determine the static loads transmitted by the bellows due to thermally induced expansion on the inner conductor and on the RF window. This paper also discusses this analysis, as well as the mechanical analysis performed to determine the final geometric shape of the bellows. Finally, a discussion of the electromagnetic analysis used to optimize the performance of the power couplers is included.

  9. New high power CW klystrons at TED

    CERN Document Server

    Beunas, A; Marchesin, R

    2003-01-01

    Thales Electron Devices (TED) has been awarded a contract by CERN to develop and produce 20 units of the klystrons needed to feed the Large Hadrons Collider (LHC). Each of these delivers 300 kW of CW RF power at 400 MHz. Three klystrons have been delivered to CERN up to now.

  10. Eighth CW and High Average Power RF Workshop

    CERN Document Server

    2014-01-01

    We are pleased to announce the next Continuous Wave and High Average RF Power Workshop, CWRF2014, to take place at Hotel NH Trieste, Trieste, Italy from 13 to 16 May, 2014. This is the eighth in the CWRF workshop series and will be hosted by Elettra - Sincrotrone Trieste S.C.p.A. (www.elettra.eu). CWRF2014 will provide an opportunity for designers and users of CW and high average power RF systems to meet and interact in a convivial environment to share experiences and ideas on applications which utilize high-power klystrons, gridded tubes, combined solid-state architectures, high-voltage power supplies, high-voltage modulators, high-power combiners, circulators, cavities, power couplers and tuners. New ideas for high-power RF system upgrades and novel ways of RF power generation and distribution will also be discussed. CWRF2014 sessions will start on Tuesday morning and will conclude on Friday lunchtime. A visit to Elettra and FERMI will be organized during the workshop. ORGANIZING COMMITTEE (OC): Al...

  11. High power CW linac in PNC

    International Nuclear Information System (INIS)

    Toyama, S.; Wang, Y.L.; Emoto, T.

    1994-01-01

    Power Reactor and Nuclear Fuel Development Corporation (PNC) is developing a high power electron linac for various applications. The electron beam is accelerated in CW operation to get maximum beam current of 100 mA and energy of 10 MeV. Crucial components such as a high power L-band klystron and a high power traveling wave resonant ring (TWRR) accelerator guides were designed and manufactured and their performance were examined. These design and results from the recent high power RF tests were described in this paper. (author)

  12. Study of a power coupler for superconducting RF cavities used in high intensity proton accelerator

    International Nuclear Information System (INIS)

    Souli, M.

    2007-07-01

    The coaxial power coupler needed for superconducting RF cavities used in the high energy section of the EUROTRANS driver should transmit 150 kW (CW operation) RF power to the protons beam. The calculated RF and dielectric losses in the power coupler (inner and outer conductor, RF window) are relatively high. Consequently, it is necessary to design very carefully the cooling circuits in order to remove the generated heat and to ensure stable and reliable operating conditions for the coupler cavity system. After calculating all type of losses in the power coupler, we have designed and validated the inner conductor cooling circuit using numerical simulations results. We have also designed and optimized the outer conductor cooling circuit by establishing its hydraulic and thermal characteristics. Next, an experiment dedicated to study the thermal interaction between the power coupler and the cavity was successfully performed at CRYOHLAB test facility. The critical heat load Qc for which a strong degradation of the cavity RF performance was measured leading to Q c in the range 3 W-5 W. The measured heat load will be considered as an upper limit of the residual heat flux at the outer conductor cold extremity. A dedicated test facility was developed and successfully operated for measuring the performance of the outer conductor heat exchanger using supercritical helium as coolant. The test cell used reproduces the realistic thermal boundary conditions of the power coupler mounted on the cavity in the cryo-module. The first experimental results have confirmed the excellent performance of the tested heat exchanger. The maximum residual heat flux measured was 60 mW for a 127 W thermal load. As the RF losses in the coupler are proportional to the incident RF power, we can deduce that the outer conductor heat exchanger performance is continued up to 800 kW RF power. Heat exchanger thermal conductance has been identified using a 2D axisymmetric thermal model by comparing

  13. Development of 20 kW input power coupler for 1.3 GHz ERL main linac. Component test at 30 kW IOT test stand

    International Nuclear Information System (INIS)

    Sakai, Hiroshi; Umemori, Kensei; Sakanaka, Shogo; Takahashi, Takeshi; Furuya, Takaaki; Shinoe, Kenji; Ishii, Atsushi; Nakamura, Norio; Sawamura, Masaru

    2009-01-01

    We started to develop an input coupler for a 1.3 GHz ERL superconducting cavity. Required input power is about 20 kW for the cavity acceleration field of 20 MV/m and the beam current of 100 mA in energy recovery operation. The input coupler is designed based on the STF-BL input coupler and some modifications are applied to the design for the CW 20 kW power operation. We fabricated input coupler components such as ceramic windows and bellows and carried out the high-power test of the components by using a 30 kW IOT power source and a test stand constructed for the highpower test. In this report, we mainly describe the results of the high-power test of ceramic window and bellows. (author)

  14. Suppression of multipacting in high power RF couplers operating with superconducting cavities

    Energy Technology Data Exchange (ETDEWEB)

    Ostroumov, P.N., E-mail: ostroumov@frib.msu.edu [Facility for Rare Isotope Beams (FRIB), Michigan State University, East Lansing, MI 48824 (United States); Kazakov, S. [Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Morris, D.; Larter, T.; Plastun, A.S.; Popielarski, J.; Wei, J.; Xu, T. [Facility for Rare Isotope Beams (FRIB), Michigan State University, East Lansing, MI 48824 (United States)

    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.

  15. Coaxial TW window for power couplers and multipactor considerations

    International Nuclear Information System (INIS)

    Hanus, X.; Mosnier, A.

    1996-01-01

    A Traveling Wave coaxial window has been studied for power couplers purposes. The main features, a reduced electrical field in the ceramic and its multipacting free shape are presented. Multipacting simulations results for other window geometries, using a conical or a cylindrical ceramic are also showed. (author)

  16. A high-power diode-laser-pumped CW Nd:YAG laser using a stable-unstable resonator

    International Nuclear Information System (INIS)

    Mudge, M.; Ostermeyer, P.; Veitch, J.; Munch, J.; Hamilton, M.W.

    2000-01-01

    Full text: The design and operation of a power-scalable diode-laser-pumped CW Nd:YAG zigzag slab laser that uses a stable-unstable resonator with a graded reflectivity mirror as an output coupler is described. We demonstrate control of the thermal lens strength in the unstable plane and weak thermal lensing in the stable plane that is independent of pump power, vital for efficient scalability. This enabled CW operation of the stable-unstable resonator with excellent near- and far-field beam quality

  17. Splitting of high power, cw proton beams

    Directory of Open Access Journals (Sweden)

    Alberto Facco

    2007-09-01

    Full Text Available A simple method for splitting a high power, continuous wave (cw proton beam in two or more branches with low losses has been developed in the framework of the EURISOL (European Isotope Separation On-Line Radioactive Ion Beam Facility design study. The aim of the system is to deliver up to 4 MW of H^{-} beam to the main radioactive ion beam production target, and up to 100 kW of proton beams to three more targets, simultaneously. A three-step method is used, which includes magnetic neutralization of a fraction of the main H^{-} beam, magnetic splitting of H^{-} and H^{0}, and stripping of H^{0} to H^{+}. The method allows slow raising and individual fine adjustment of the beam intensity in each branch.

  18. Studying quick coupler efficiency in working attachment system of single-bucket power shovel

    Science.gov (United States)

    Duganova, E. V.; Zagorodniy, N. A.; Solodovnikov, D. N.; Korneyev, A. S.

    2018-03-01

    A prototype of a quick-disconnect connector (quick coupler) with an unloaded retention mechanism was developed from the analysis of typical quick couplers used as intermediate elements for power shovels of different manufacturers. A method is presented, allowing building a simulation model of the quick coupler prototype as an alternative to physical modeling for further studies.

  19. Multipactor Simulations of the SPL Power Coupler

    CERN Document Server

    Burt, A; Dexter, A C; Calaga, R; Montesinos, E; Author, F; Author, G

    2010-01-01

    Mul­ti­pactor is a lim­it­ing fac­tor in many RF power cou­plers. The SPL cou­pler is pro­posed to have a con­i­cal match­ing sec­tion be­tween the win­dow and the coax­i­al sec­tion how­ev­er this sec­tion must be checked for mul­ti­pactor. Mul­ti­pactor sim­u­la­tions of the cou­pler up to a few MW's of power were per­formed using a va­ri­ety of dif­fer­ent codes and the re­sults were com­pared. Sim­u­la­tions were per­formed in the con­i­cal and straight coax­i­al sec­tions.

  20. Baking Arithmetic and Error Analyses for PEFP Fundamental Power Couplers

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Liping; An, Sun; Tang, Yazhe; Cho, Yong Sub [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2009-05-15

    The Proton Engineering Frontier Project (PEFP) is considering developing and using SRF technology to accelerate a proton beam at 700 MHz in its present project and its extended project (PEP). The first section of the PEFP SRF linac (SCL) is composed of low-beta cryomodules. Each cryomodule has three 5-cell cavities and each cavity has one fundamental power coupler (FPC). Before the high power RF processing, each FPC needs to be baked out for 24 hours at 200 degrees Celsius ( .deg. C). The whole control system is described in reference, in this system, the temperature in the baking-box need to be changed according to three straight lines with different slope. This paper described how we can make the temperature of the baking-box changed according to the required values.

  1. Baking Arithmetic and Error Analyses for PEFP Fundamental Power Couplers

    International Nuclear Information System (INIS)

    Zhang, Liping; An, Sun; Tang, Yazhe; Cho, Yong Sub

    2009-01-01

    The Proton Engineering Frontier Project (PEFP) is considering developing and using SRF technology to accelerate a proton beam at 700 MHz in its present project and its extended project (PEP). The first section of the PEFP SRF linac (SCL) is composed of low-beta cryomodules. Each cryomodule has three 5-cell cavities and each cavity has one fundamental power coupler (FPC). Before the high power RF processing, each FPC needs to be baked out for 24 hours at 200 degrees Celsius ( .deg. C). The whole control system is described in reference, in this system, the temperature in the baking-box need to be changed according to three straight lines with different slope. This paper described how we can make the temperature of the baking-box changed according to the required values

  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. Preliminary design of high-power wave-guide/transmission system for multimegawatt CW requirements of 100 MeV proton Linac

    International Nuclear Information System (INIS)

    Shrivastava, Purushottam; Wanmode, Y.D.; Hannurkar, P.R.

    2002-01-01

    Development of a 100 MeV CW proton Linac has been planned at CAT. This Linac will be needing CW rf power in the frequency ranges of 350 MHz and 700 MHz for its RFQ and DTL/CCDTL/SFDTL structures respectively. The power to the accelerating structures will be produced by either 1 MW CW or 250 kW CW klystron/inductive output tubes (HOM IOTs). The power needed by respective feed points in the structure is max. 250 kW which will be powered by splitting the power from 1 MW klystron/klystrode into four channels by using a wave-guide system. In case of using 250 kW tubes the power to the structures will be provided directly from each tube. Two types of wave-guide transmission system have been considered, viz WR 2300 for 350 MHz rf needs and WR 1500 for 700 MHz rf needs. The typical wave-guide system has been designed using the 1 MW CW klystron followed by wave-guide filter, dual directional coupler, high-power circulator, three 3 dB magic TEE power dividers to split the main channel into four equal channels of 250 kW each. Each individual channel has dual directional couplers, flexible wave-guide sections and high power ceramic vacuum window. The circulator and each power divider is terminated into the isolated ports by high power CW loads. Out of the four channels three channels have phase shifters. Present paper describes the technological aspects and design specifications-considerations for these stringent requirements. (author)

  4. Development of fundamental power coupler for C-ADS superconducting elliptical cavities

    Science.gov (United States)

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

    2017-06-01

    5-cell elliptical cavities have been selected for the main linac of the China Accelerator Driven sub-critical System (C-ADS) in the medium energy section. According to the design, each cavity should be driven with radio frequency (RF) energy up to 150 kW by a fundamental power coupler (FPC). As the cavities work with high quality factor and high accelerating gradient, the coupler should keep the cavity from contamination in the assembly procedure. To fulfil the requirements, a single-window coaxial type coupler was designed with the capabilities of handling high RF power, class 10 clean room assembly, and heat load control. This paper presents the coupler design and gives details of RF design, heat load optimization and thermal analysis as well as multipacting simulations. In addition, a primary high power test has been performed and is described in this paper. Supported by China ADS Project (XDA03020000) and National Natural Science Foundation of China (11475203)

  5. 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)

  6. High-power single-mode cw dye ring laser

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, H W; Stein, L; Froelich, D; Fugger, B; Welling, H [Technische Univ. Hannover (Germany, F.R.). Inst. fuer Angewandte Physik

    1977-12-01

    Due to spatial hole burning, standing-wave dye lasers require a large amount of selectivity inside the cavity for single-mode operation. The output power of these lasers is limited by losses caused by the frequency selecting elements. In a travelling-wave laser, on the other hand, spatial hole burning does not exist, thereby eliminating the need for high selectivity. A travelling-wave cw dye laser was realized by unidirectional operation of a ring laser, yielding single mode output powers of 1.2 W at 595 nm and of 55 mW in the UV-region with intracavity frequency doubling.

  7. Variable Power, Short Microwave Pulses Generation using a CW Magnetron

    Directory of Open Access Journals (Sweden)

    CIUPA, R.

    2011-05-01

    Full Text Available Fine control of microwave power radiation in medical and scientific applications is a challenging task. Since a commercial Continuous Wave (CW magnetron is the most inexpensive microwave device available today on the market, it becomes the best candidate for a microwave power generator used in medical diathermy and hyperthermia treatments or high efficiency chemical reactions using microwave reactors as well. This article presents a new method for driving a CW magnetron with short pulses, using a modified commercial Zero Voltage Switching (ZVS inverter, software driven by a custom embedded system. The microwave power generator designed with this method can be programmed for output microwave pulses down to 1% of the magnetron's power and allows microwave low frequency pulse modulation in the range of human brain electrical activity, intended for medical applications. Microwave output power continuous control is also possible with the magnetron running in the oscillating area, using a dual frequency Pulse Width Modulation (PWM, where the low frequency PWM pulse is modulating a higher resonant frequency required by the ZVS inverter's transformer. The method presented allows a continuous control of both power and energy (duty-cycle at the inverter's output.

  8. Testing Procedures and Results of the Prototype Fundamental Power Coupler for the Spallation Neutron Source

    International Nuclear Information System (INIS)

    M. Stirbet; I.E. Campisi; E.F. Daly; G.K. Davis; M. Drury; P. Kneisel; G. Myneni; T. Powers; W.J. Schneider; K.M. Wilson; Y. Kang; K.A. Cummings; T. Hardek

    2001-01-01

    High-power RF testing with peak power in excess of 500 kW has been performed on prototype Fundamental Power Couplers (FPC) for the Spallation Neutron Source superconducting (SNS) cavities. The testing followed the development of procedures for cleaning, assembling and preparing the FPC for installation in the test stand. The qualification of the couplers has occurred for the time being only in a limited set of conditions (travelling wave, 20 pps) as the available RF system and control instrumentation are under improvement

  9. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Rajesh; Jose, Mentes; Singh, G.N. [Ion Accelerator Development Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Kumar, Girish [Department of Electrical Engineering, IIT Bombay, Mumbai 400076,India (India); Bhagwat, P.V. [Ion Accelerator Development Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    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.

  11. Low power cw-laser signatures on human skin

    International Nuclear Information System (INIS)

    Lihachev, A; Lesinsh, J; Jakovels, D; Spigulis, J

    2011-01-01

    Impact of cw laser radiation on autofluorescence features of human skin is studied. Two methods of autofluorescence detection are applied: the spectral method with the use of a fibreoptic probe and spectrometer for determining the autofluorescence recovery kinetics at a fixed skin area of ∼12 mm 2 , and the multispectral visualisation method with the use of a multispectral imaging camera for visualising long-term autofluorescence changes in a skin area of ∼4 cm 2 . The autofluorescence recovery kinetics after preliminary laser irradiation is determined. Skin autofluorescence images with visible long-term changes - 'signatures' of low power laser treatment are acquired. (application of lasers and laser-optical methods in life sciences)

  12. High-power RF window and coupler development for the PEP-II B Factory

    International Nuclear Information System (INIS)

    Neubauer, M.; Fant, K.; Hodgson, J.; Judkins, J.; Schwarz, H.; Rimmer, R.A.

    1995-05-01

    We describe the fabrication and testing of the RF windows designed to transmit power to the PEP-II 476 MHz cavities. Design choices to maximize the reliability of the window are discussed. Fabrication technologies for the window are described and finite-element analysis of the assembly process is presented. Conditioning and high-power testing of the window are discussed. Design of the coupler assembly including the integration of the window and other components is reported

  13. Design of the new couplers for C-ADS RFQ

    Science.gov (United States)

    Shi, Ai-Min; Sun, Lie-Peng; Zhang, Zhou-Li; Xu, Xian-Bo; Shi, Long-Bo; Li, Chen-Xing; Wang, Wen-Bin

    2015-04-01

    A new special coupler with a kind of bowl-shaped ceramic window for a proton linear accelerator named the Chinese Accelerator Driven System (C-ADS) at the Institute of Modern Physics (IMP) has been simulated and constructed and a continuous wave (CW) beam commissioning through a four-meter long radio frequency quadruple (RFQ) was completed by the end of July 2014. In the experiments of conditioning and beam, some problems were promoted gradually such as sparking and thermal issues. Finally, two new couplers were passed with almost 110 kW CW power and 120 kW pulsed mode, respectively. The 10 mA intensity beam experiments have now been completed, and the couplers during the operation had no thermal or electro-magnetic problems. The detailed design and results are presented in the paper. Supported by Strategic Priority Research Program of Chinese Academy of Sciences (XDA03020500)

  14. High power coupler issues in normal conducting and superconducting accelerator applications

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, H. [High Energy Accelerator Research Organization, Tsukuba, Ibaraki (Japan)

    2001-02-01

    The ceramic material (Al{sub 2}O{sub 3}) commonly used for the klystron output coupler in normal conducting, and for an input coupler to superconducting cavities is one of the most troublesome parts in accelerator applications. But the performance can be improved very much by starting with high purity (>99.9%) alumina powder of controlled grain-size (0.1-0.5-{mu}m), and reducing the magnesium (Mg) sintering-binder to lower the dielectric loss to the order of 10{sup -4} at S-band frequencies. It has been confirmed that the new ceramic can stand a peak S-band frequency rf power of up to 300 MW and 2.5 {mu}sec pulse width. (author)

  15. Design and operation of 140 GHz gyrotron oscillators for power levels up to 1 MW CW

    Energy Technology Data Exchange (ETDEWEB)

    Jory, H.; Bier, R.; Craig, L.J.; Felch, K.; Ives, L.; Lopez, N.; Spang, S.

    1986-12-01

    Varian has designed and tested 140 GHz gyrotron oscillators that have generated output powers of 100 kW CW and 200 kW for 1 ms pulses. Upcoming tubes will be designed to operate at power levels of 200 kW CW and ultimately up to 1 MW CW. The important design considerations which are addressed in the higher power tubes include the design of the electron gun, interaction circuit, and output window. These issues will be discussed and the results of the earlier 140 GHz gyrotron work at Varian will be summarized.

  16. Design and operation of 140 GHz gyrotron oscillators for power levels up to 1 MW CW

    International Nuclear Information System (INIS)

    Jory, H.; Bier, R.; Craig, L.J.; Felch, K.; Ives, L.; Lopez, N.; Spang, S.

    1986-12-01

    Varian has designed and tested 140 GHz gyrotron oscillators that have generated output powers of 100 kW CW and 200 kW for 1 ms pulses. Upcoming tubes will be designed to operate at power levels of 200 kW CW and ultimately up to 1 MW CW. The important design considerations which are addressed in the higher power tubes include the design of the electron gun, interaction circuit, and output window. These issues will be discussed and the results of the earlier 140 GHz gyrotron work at Varian will be summarized

  17. Study of a superconducting spoke-type cavity and of its associated power coupler

    International Nuclear Information System (INIS)

    Mielot, Ch.

    2004-12-01

    This work deals with the study of a spoke-type cavity and its associated power coupler. The results of this study are used in the framework of the high power proton linear accelerator of the experimental accelerator-driven system project (XADS). The cavity (F=352 MHz, β=0.35) was tested at 4 K and 2 K. The results at 4 K gave good margins toward XADS requirements that increase the reliability of a spoke based driver. At 2 K the accelerating field reached is the highest in the world for spoke cavities: 16 MV/M. The position and diameter of the coupling have been optimized in order to decrease the HF losses and avoid multi-factor risk. In order to decrease HF losses (taking into account the 20 kW power fed into the cavity) the electric coupling mode has been chosen. Different types of ceramic windows have been studied in order to make this critical point of the coupler reliable: coaxial disk with or without chokes or empty coaxial cylinder. The optimization process focused on the reflected power, the losses in the ceramic and the surface electric field. The risk with chokes has been modeled and studied with the propagation lines theory. A systematic study of the different windows has been done regarding the geometrical parameters. The disk without chokes seems to be a good solution for our application. The power source will be a solid state amplifier (for reliability and modularity reasons). An all over coaxial coupler can be designed and will be fabricated and tested soon. (author)

  18. Study of a power coupler for superconducting RF cavities used in high intensity proton accelerator; Etude et developpement d'un coupleur de puissance pour les cavites supraconductrices destinees aux accelerateurs de protons de haute intensite

    Energy Technology Data Exchange (ETDEWEB)

    Souli, M

    2007-07-15

    The coaxial power coupler needed for superconducting RF cavities used in the high energy section of the EUROTRANS driver should transmit 150 kW (CW operation) RF power to the protons beam. The calculated RF and dielectric losses in the power coupler (inner and outer conductor, RF window) are relatively high. Consequently, it is necessary to design very carefully the cooling circuits in order to remove the generated heat and to ensure stable and reliable operating conditions for the coupler cavity system. After calculating all type of losses in the power coupler, we have designed and validated the inner conductor cooling circuit using numerical simulations results. We have also designed and optimized the outer conductor cooling circuit by establishing its hydraulic and thermal characteristics. Next, an experiment dedicated to study the thermal interaction between the power coupler and the cavity was successfully performed at CRYOHLAB test facility. The critical heat load Qc for which a strong degradation of the cavity RF performance was measured leading to Q{sub c} in the range 3 W-5 W. The measured heat load will be considered as an upper limit of the residual heat flux at the outer conductor cold extremity. A dedicated test facility was developed and successfully operated for measuring the performance of the outer conductor heat exchanger using supercritical helium as coolant. The test cell used reproduces the realistic thermal boundary conditions of the power coupler mounted on the cavity in the cryo-module. The first experimental results have confirmed the excellent performance of the tested heat exchanger. The maximum residual heat flux measured was 60 mW for a 127 W thermal load. As the RF losses in the coupler are proportional to the incident RF power, we can deduce that the outer conductor heat exchanger performance is continued up to 800 kW RF power. Heat exchanger thermal conductance has been identified using a 2D axisymmetric thermal model by comparing

  19. Bessel-function analysis of the optimized star coupler for uniform power splitting.

    Science.gov (United States)

    Song, G Hugh; Park, Mahn Yong

    2004-08-01

    An optimized N x N planar optic star coupler that utilizes directional coupling of arrayed waveguides for uniform power splitting is analyzed on the basis of special properties of the involved Bessel-function series. The analysis has provided a remarkably simple, novel basic design formula for such a device with much needed physical insights into the unique diffraction properties. For the analysis of diffraction from the end of directionally coupled arrayed waveguides, many useful formulas around the Bessel functions, such as the addition theorem and the Kepler-Bessel series, have been given in new forms.

  20. 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.

  1. The Prototype Fundamental Power Coupler For The Spallation Neutron Source Superconducting Cavities: Design And Initial Test Results

    International Nuclear Information System (INIS)

    K. M. Wilson; I. E. Campisi; E. F. Daly; G. K. Davis; M. Drury; J. E. Henry; P. Kneisel; G. Myneni; T. Powers; W. J. Schneider; M. Stirbet; Y. Kang; K. Cummings; T. Hardek

    2001-01-01

    Each of the 805 MHz superconducting cavities of the Spallation Neutron Source (SNS) is powered via a coaxial Fundamental Power Coupler (FPC) with a 50 Omega impedance and a warm planar alumina window. The design is derived from the experience of other laboratories; in particular, a number of details are based on the coupler developed for the KEK B-Factory superconducting cavities. However, other design features have been modified to account for the fact that the SNS FPC will transfer a considerably lower average power than the KEK-B coupler. Four prototypes have been manufactured so far, and preliminary tests performed on two of them at Los Alamos National Laboratory (LANL). During these tests, peak powers of over 500 kW were transferred through the couplers in the test stand designed and built for this purpose. This paper gives details of the coupler design and of the results obtained from the RF tests on the test stand during the last few months. A more comprehensive set of tests is planned for the near future

  2. The propagation of high power CW scanning electron beam in air

    International Nuclear Information System (INIS)

    Korenev, Sergey; Korenev, Ivan

    2002-01-01

    The question of propagation of high power electron beam in air presents the scientific and applied interests. The high power (80 kW) CW electron accelerator 'Rhodotron' with kinetic energy of electrons 5 and 10 MeV was used in the experiments. The experimental results for propagation of scanning electron beams in air are presented and discussed

  3. Coupler developments at CERN

    International Nuclear Information System (INIS)

    Cavallari, G.; Chiaveri, E.; Haebel, E.; Legendre, P.; Weingarten, W.

    1988-01-01

    This paper discusses the coupler developments that have taken place at CERN since the last RF superconductivity workshop. At that time beam tube coupling was just starting to be examined. It was found that in restricting the number of cells to four with the correct amount of intercell coupling, and endcells compensated simultaneously for several modes, trapped modes can be avoided at least up to three and a half times the fundamental mode frequency. This result is regarded as a sufficiently safe basis to switch over to beam tube coupling with two higher order mode (hom) couplers, one on each side and with 65 degrees in between them, and in addition one beam tube power coupler. The characteristics of the cavity and the machine determine the basic coupler specifications. Four designs are discussed for hom couplers. 22 reference, 15 figures, 2 tables

  4. Conceptual design of a sapphire loaded coupler for superconducting radio-frequency 1.3 GHz cavities

    Science.gov (United States)

    Xu, Chen; Tantawi, Sami

    2016-02-01

    This paper explores a hybrid mode rf structure that served as a superconducting radio-frequency coupler. This application achieves a reflection S(1 ,1 ) varying from 0 to -30 db and delivers cw power at 7 KW. The coupler has good thermal isolation between the 2 and 300 K sections due to vacuum separation. Only one single hybrid mode can propagate through each section, and no higher order mode is coupled. The analytical and numerical analysis for this coupler is given and the design is optimized. The coupling mechanism to the cavity is also discussed.

  5. Conceptual design of a sapphire loaded coupler for superconducting radio-frequency 1.3 GHz cavities

    Directory of Open Access Journals (Sweden)

    Chen Xu

    2016-02-01

    Full Text Available This paper explores a hybrid mode rf structure that served as a superconducting radio-frequency coupler. This application achieves a reflection S_{(1,1} varying from 0 to −30  db and delivers cw power at 7 KW. The coupler has good thermal isolation between the 2 and 300 K sections due to vacuum separation. Only one single hybrid mode can propagate through each section, and no higher order mode is coupled. The analytical and numerical analysis for this coupler is given and the design is optimized. The coupling mechanism to the cavity is also discussed.

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

    Science.gov (United States)

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

    2005-01-01

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

  7. Preliminary design of high-power wave-guide/transmission system

    Indian Academy of Sciences (India)

    ... CW klystron followed by wave-guide filter, dual directional coupler, high-power circulator, three 3 dB magic TEE power dividers to split the main channel into four equal channels of 250 kW each. Each individual channel has dual directional couplers, flexible wave-guide sections and high power ceramic vacuum window.

  8. CW 100MW microwave power transfer in space

    International Nuclear Information System (INIS)

    Takayama, K.; Hiramatsu, S.; Shiho, M.

    1991-01-01

    A proposal is made for high-power microwave transfer in space. The concept consists in a microwave power station integrating a multistage microwave free-electron laser and asymmetric dual-reflector system. Its use in space is discussed. 9 refs., 2 figs., 1 tab

  9. Arbitrary-ratio power splitter based on nonlinear multimode interference coupler

    International Nuclear Information System (INIS)

    Tajaldini, Mehdi; Jafri, Mohd Zubir Mat

    2015-01-01

    We propose an ultra-compact multimode interference (MMI) power splitter based on nonlinear effects from simulations using nonlinear modal propagation analysis (NMPA) cooperation with finite difference Method (FDM) to access free choice of splitting ratio. Conventional multimode interference power splitter could only obtain a few discrete ratios. The power splitting ratio may be adjusted continuously while the input set power is varying by a tunable laser. In fact, using an ultra- compact MMI with a simple structure that is launched by a tunable nonlinear input fulfills the problem of arbitrary-ratio in integrated photonics circuits. Silicon on insulator (SOI) is used as the offered material due to the high contrast refractive index and Centro symmetric properties. The high-resolution images at the end of the multimode waveguide in the simulated power splitter have a high power balance, whereas access to a free choice of splitting ratio is not possible under the linear regime in the proposed length range except changes in the dimension for any ratio. The compact dimensions and ideal performance of the device are established according to optimized parameters. The proposed regime can be extended to the design of M×N arbitrary power splitters ratio for programmable logic devices in all optical digital signal processing. The results of this study indicate that nonlinear modal propagation analysis solves the miniaturization problem for all-optical devices based on MMI couplers to achieve multiple functions in a compact planar integrated circuit and also overcomes the limitations of previously proposed methods for nonlinear MMI

  10. Arbitrary-ratio power splitter based on nonlinear multimode interference coupler

    Energy Technology Data Exchange (ETDEWEB)

    Tajaldini, Mehdi [School of Physics, Universiti Sains Malaysia, 11800 Pulau Pinang (Malaysia); Young Researchers and Elite Club, Baft Branch, Islamic Azad University, Baft (Iran, Islamic Republic of); Jafri, Mohd Zubir Mat [School of Physics, Universiti Sains Malaysia, 11800 Pulau Pinang (Malaysia)

    2015-04-24

    We propose an ultra-compact multimode interference (MMI) power splitter based on nonlinear effects from simulations using nonlinear modal propagation analysis (NMPA) cooperation with finite difference Method (FDM) to access free choice of splitting ratio. Conventional multimode interference power splitter could only obtain a few discrete ratios. The power splitting ratio may be adjusted continuously while the input set power is varying by a tunable laser. In fact, using an ultra- compact MMI with a simple structure that is launched by a tunable nonlinear input fulfills the problem of arbitrary-ratio in integrated photonics circuits. Silicon on insulator (SOI) is used as the offered material due to the high contrast refractive index and Centro symmetric properties. The high-resolution images at the end of the multimode waveguide in the simulated power splitter have a high power balance, whereas access to a free choice of splitting ratio is not possible under the linear regime in the proposed length range except changes in the dimension for any ratio. The compact dimensions and ideal performance of the device are established according to optimized parameters. The proposed regime can be extended to the design of M×N arbitrary power splitters ratio for programmable logic devices in all optical digital signal processing. The results of this study indicate that nonlinear modal propagation analysis solves the miniaturization problem for all-optical devices based on MMI couplers to achieve multiple functions in a compact planar integrated circuit and also overcomes the limitations of previously proposed methods for nonlinear MMI.

  11. CW 100MW microwave power transfer in space

    International Nuclear Information System (INIS)

    Takayama, K.; Hiramatsu, S.; Shiho, M.

    1991-01-01

    A linear multistage MFEL has been considered as a possible power source for future linear colliders; however, the single-stage experiment cannot be straightforwardly extrapolated to the multistage MFEL. Nevertheless, extensive theoretical and computational studies have demonstrated the feasibility of multistaging. Based on the authors current understanding of the MFEL, they developed the idea of a circular microwave power station (MPS) driven with a single high current beam where many FEL stages are placed along a circle and the remarkable high power of microwave (mw) is generated at each stage. The total power produced is linearly proportional to the number of FEL stages. This huge mw power can be emitted from a large parabola antenna; propagates in space and can be received by a receiver such as parabola antenna or rectenna

  12. High-power CW LINAC for food irradiation

    International Nuclear Information System (INIS)

    Alimov, A.S.; Knapp, E.A.; Shvedunov, V.I.; Trower, W.P.

    2000-01-01

    The continuing high profile food poisoning incidents are beginning to attract food processors using electron and γ-ray sterilization technologies. The present method of choice uses radioactive isotopes but high-power electron particle accelerators are proving an increasingly attractive alternative. We are developing a family of compact industrial continuous wave linear accelerators which produce electrons with energies from 600 keV in increments of ∼600 keV and with beam power of 30 kW increasing in increments of 30 kW. Here, we describe the performance of our 1st section that accelerates 15 keV gun electrons to relativistic energies and then we sketch the design of the less demanding subsequent sections that we are now constructing

  13. Asymmetric focusing study from twin input power couplers using realistic rf cavity field maps

    Directory of Open Access Journals (Sweden)

    Colwyn Gulliford

    2011-03-01

    Full Text Available Advanced simulation codes now exist that can self-consistently solve Maxwell’s equations for the combined system of an rf cavity and a beam bunch. While these simulations are important for a complete understanding of the beam dynamics in rf cavities, they require significant time and computing power. These techniques are therefore not readily included in real time simulations useful to the beam physicist during beam operations. Thus, there exists a need for a simplified algorithm which simulates realistic cavity fields significantly faster than self-consistent codes, while still incorporating enough of the necessary physics to ensure accurate beam dynamics computation. To this end, we establish a procedure for producing realistic field maps using lossless cavity eigenmode field solvers. This algorithm incorporates all relevant cavity design and operating parameters, including beam loading from a nonrelativistic beam. The algorithm is then used to investigate the asymmetric quadrupolelike focusing produced by the input couplers of the Cornell ERL injector cavity for a variety of beam and operating parameters.

  14. Analysis and comparison between electric and magnetic power couplers for accelerators in Free Electron Lasers (FEL)

    Energy Technology Data Exchange (ETDEWEB)

    Serpico, C., E-mail: claudio.serpico@elettra.eu [Elettra - Sincrotrone Trieste, Trieste (Italy); Grudiev, A. [CERN, Geneva (Switzerland); Vescovo, R. [University of Trieste, Trieste (Italy)

    2016-10-11

    Free-electron lasers represent a new and exciting class of coherent optical sources possessing broad wavelength tunability and excellent optical-beam quality. The FERMI seeded free-electron laser (FEL), located at the Elettra laboratory in Trieste, is driven by a 200 m long, S-band linac: the high energy part of the linac is equipped with 6 m long backward traveling wave (BTW) structures. The structures have small iris radius and a nose cone geometry which allows for high gradient operation. Development of new high-gradient, S-band accelerating structures for the replacement of the existing BTWs is under consideration. This paper investigates two possible solutions for the RF power couplers suitable for a linac driven FEL which require reduced wakefields effects, high operating gradient and very high reliability. The first part of the manuscript focuses on the reduction of residual field asymmetries, while in the second analyzes RF performances, the peak surface fields and the expected breakdown rate. In the conclusion, two solutions are compared and pros and cons are highlighted.

  15. Analysis and comparison between electric and magnetic power couplers for accelerators in Free Electron Lasers (FEL)

    Science.gov (United States)

    Serpico, C.; Grudiev, A.; Vescovo, R.

    2016-10-01

    Free-electron lasers represent a new and exciting class of coherent optical sources possessing broad wavelength tunability and excellent optical-beam quality. The FERMI seeded free-electron laser (FEL), located at the Elettra laboratory in Trieste, is driven by a 200 m long, S-band linac: the high energy part of the linac is equipped with 6 m long backward traveling wave (BTW) structures. The structures have small iris radius and a nose cone geometry which allows for high gradient operation. Development of new high-gradient, S-band accelerating structures for the replacement of the existing BTWs is under consideration. This paper investigates two possible solutions for the RF power couplers suitable for a linac driven FEL which require reduced wakefields effects, high operating gradient and very high reliability. The first part of the manuscript focuses on the reduction of residual field asymmetries, while in the second analyzes RF performances, the peak surface fields and the expected breakdown rate. In the conclusion, two solutions are compared and pros and cons are highlighted.

  16. High-power and highly reliable 638-nm band BA-LD for CW operation

    Science.gov (United States)

    Nishida, Takehiro; Kuramoto, Kyosuke; Abe, Shinji; Kusunoki, Masatsugu; Miyashita, Motoharu; Yagi, Tetsuya

    2018-02-01

    High-power laser diodes (LDs) are strongly demanded as light sources of display applications. In multiple spatial light modulator-type projectors or liquid crystal displays, the light source LDs are operated under CW condition. The high-power 638-nm band broad-area LD for CW operation was newly developed. The LD consisted of two stripes with each width of 75 μm to reduce both an optical power density at a front facet and a threshold current. The newly improved epitaxial technology was also applied to the LD to suppress an electron overflow from an active layer. The LD showed superior output characteristics, such as output of 1.77 W at case temperature of 55 °C with wall plug efficiency (WPE) of 23%, which was improved by 40% compared with the current product. The peak WPE at 25 °C reached 40.6% under the output power of 2.37 W, CW, world highest.

  17. Diode-side-pumped 131 W, 1319 nm single-wavelength cw Nd:YAG laser.

    Science.gov (United States)

    Haiyong, Zhu; Ge, Zhang; Chenghui, Huang; Yong, Wei; Lingxiong, Huang; Jing, Chen; Weidong, Chen; Zhenqiang, Chen

    2007-01-20

    A diode-side-pumped high-power 1319 nm single-wavelength Nd:YAG continuous wave (cw) laser is described. Through reasonable coating design of the cavity mirrors, the 1064 nm strongest line as well as the 1338 nm one have been successfully suppressed. The laser output powers corresponding to four groups of different output couplers operating at 1319 nm single wavelength have been compared. The output coupler with the transmission T=5.3% has the highest output power, and a 131 W cw output power was achieved at the pumping power of 555 W. The optical-optical conversion efficiency is 23.6%, and the slope efficiency is 46%. The output power is higher than the total output power of the dual-wavelength laser operating at 1319 nm and 1338 nm in the experiment.

  18. WAVEGUIDE COUPLER KICK TO BEAM BUNCH AND CURRENT DEPENDENCY ON SRF CAVITIES

    International Nuclear Information System (INIS)

    Genfa Wu; Haipeng Wang; Charles Reece; Robert Rimmer

    2008-01-01

    JLAB SRF cavities employ waveguide type fundamental power couplers (FPC). The FPC design for the 7-cell upgrade cavities was optimized to minimize the dipole field kick. For continuous wave (CW) operation, the forwarding RF power will be at different magnitude to drive the different beam current and cavity gradient. This introduces some deviation from optimized FPC field for varying beam loading. This article analyzes the beam behavior both in centroid kick and head-tail kick under different beam loading conditions

  19. Analysis of RF section of 250 kW CW C-Band high power klystron

    International Nuclear Information System (INIS)

    Badola, Richa; Kaushik, Meenu; Baloda, Suman; Kirti; Vrati; Lamba, O.S.; Joshi, L.M.

    2012-01-01

    Klystron is a microwave tube which is used as a power amplifier in various applications like radar, particle accelerators and thermonuclear reactors. The paper deals with the analysis of RF section of 250 kW CW C band high power klystron for 50 to 60 kV beam voltage The simulation is done using Poisson's superfish and AJ disk software's Design of cavity is done using superfish. The result of superfish is used to decide the dimensions of the geometry of the cavity and AJ disk is used to determined the centre to centre distances between the cavities in order to obtain the desired powers. (author)

  20. Operation of a CW high power RFQ test cavity: The CRNL 'sparkers'

    International Nuclear Information System (INIS)

    Hutcheon, R.M.; Schriber, S.O.; Brown, J.C.; Clements, D.W.; Campbell, H.F.; McMichael, G.E.; De Jong, M.S.

    1984-01-01

    A 270 MHz RFQ structure with 365 mm long unmodulated vanes and a 2.5 mm minimum vane-to-vane gap was used to study cw operation at surface fields in excess of 30 MV/m. The brazed OFHC solid copper structure is flood cooled and couples rf power by a drive 100p at the centre of one quadrant. Surface electric fields equivalent to twice the Kilpatrick limit were obtained at 39 kW power. The structure was rapidly conditioned with alternating periods of pulsed and cw operation to levels above 45 kW. Bremsstrahlung end point energies were used as a measure of peak vane-to-vane voltage. Several interesting observations have been made. Glowing pinpoints of light were seen near the vane tips, some extinguishing with time, others appearing - but their number and intensity increasing with rf power. Microdischarges were seen, consisting of very small localized flashes of light between the vane tips, usually accompanied by a complete collapse and re-establishment of the structure rf field over a 20 μs interval. The frequency of field collapses varied with power but was independent of gas pressure and species up to 4x10 -3 Pa. As structure power was increased above the conditioned level, a rapid succession of microdischarges would occur, increasing the reflected power beyond the fast trip level. (orig.)

  1. Advances in High Power Calorimetric Matched Loads for Short Pulses and CW Gyrotrons

    International Nuclear Information System (INIS)

    Bin, W.M.; Bruschi, A.; Cirant, S.; Gandini, F.; Granucci, G.; Mellera, V.; Muzzini, V.; Nardone, A.; Sozzi, C.; Spinicchia, N.

    2006-01-01

    The development of high power gyrotrons for plasma physics research needs proper matched and calorimetric loads able to absorb and measure the power, which nowadays is foreseen to be as high as 2 MW during CW operations. To this end IFP/CNR has developed a family of matched loads useful in the mm-wave frequency band for applications ranging from a few ms to CW in pulse length. The different loads in the family, made of an integrating sphere with a partially reflecting coating on the inner wall, are characterized by having the same absorbing geometry for the incoming beam and a different heat removal system for the specific application. Some important advances have been recently achieved from the point of view of the uniformity of power distribution on the absorbing wall and of the load construction. With high precision achieved in the coating thickness a better control of the heating power distribution is possible by proper shaping of the local reflectivity, in addition to the shaping of the mirror dispersing the input beam. A more sophisticated model describing the power distribution has been developed, taking into account a variable thickness of the absorbing coating, the proper shape of the spreading mirror, the frequency of the incoming radiation and the shape of the input beam. Lower coating thickness is shown to be preferable, at equal local reflectivity, from the point of view of a lower peak temperature and thermal stress. The paper describes a load with variable coating thickness along the meridian of the sphere, showing a uniform power deposition on the inner walls. The cooling pipe is completely electroformed on the spherical copper shell, ensuring the maintenance of the correct curvature of the inner surface and a fast heat conduction from the absorbing coating to the water through the thin copper body. For CW use all heated parts of the load must be cooled and this is achieved by 16 electroformed spiral channels. Both short pulse loads (0.1-1 s) and

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

    Science.gov (United States)

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

    2005-01-01

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

  3. Design and construction of a 500 KW CW, 400 MHz klystron to be used as RF power source for LHC/RF component tests

    CERN Document Server

    Frischholz, Hans; Pearson, C

    1998-01-01

    A 500 kW cw klystron operating at 400 MHz was developed and constructed jointly by CERN and SLAC for use as a high-power source at CERN for testing LHC/RF components such as circulators, RF absorbers and superconducting cavities with their input couplers. The design is a modification of the 353 MHz SLAC PEP-I klystron. More than 80% of the original PEP-I tube parts could thus be incorporated in the LHC test klystron which resulted in lower engineering costs as well as reduced development and construction time. The physical length between cathode plane and upper pole plate was kept unchanged so that a PEP-I tube focusing solenoid, available at CERN, could be re-used. With the aid of the klystron simulation codes JPNDISK and CONDOR, the design of the LHC tube was accomplished, which resulted in a tube with noticeably higher efficiency than its predecessor, the PEP-I klystron. The integrated cavities were redesigned using SUPERFISH and the output coupling circuit, which also required redesigning, was done with t...

  4. Design of spherical electron gun for ultra high frequency, CW power inductive output tube

    International Nuclear Information System (INIS)

    Kaushik, Meenu; Joshi, L. M.

    2016-01-01

    Inductive Output Tube (IOT) is an amplifier that usually operates in UHF range. It is an electron tube whose basic structure is similar to conventional vacuum devices. This device is widely used in broadcast applications but is now being explored for scientific applications also specifically, particle accelerators and fusion plasma heating purposes. The paper describes the design approach of a spherical gridded electron gun of a 500 MHz, 100 kW CW power IOT. The electron gun structure has been simulated and optimized for operating voltage and current of 40kV and 3.5 A respectively. The electromagnetic analysis of this spherical electron gun has been carried out in CST and TRAK codes.

  5. Design of spherical electron gun for ultra high frequency, CW power inductive output tube

    Energy Technology Data Exchange (ETDEWEB)

    Kaushik, Meenu, E-mail: mkceeri@gmail.com; Joshi, L. M., E-mail: lmj1953@gmail.com [Microwave Tubes Division, CSIR-Central Electronics Engineering Research Institute (CEERI), Pilani, Rajasthan (India); Academy of Scientific and Innovative Research (AcSIR), New Delhi (India)

    2016-03-09

    Inductive Output Tube (IOT) is an amplifier that usually operates in UHF range. It is an electron tube whose basic structure is similar to conventional vacuum devices. This device is widely used in broadcast applications but is now being explored for scientific applications also specifically, particle accelerators and fusion plasma heating purposes. The paper describes the design approach of a spherical gridded electron gun of a 500 MHz, 100 kW CW power IOT. The electron gun structure has been simulated and optimized for operating voltage and current of 40kV and 3.5 A respectively. The electromagnetic analysis of this spherical electron gun has been carried out in CST and TRAK codes.

  6. Development of an electron gun for high power CW electron linac

    International Nuclear Information System (INIS)

    Yamazaki, Yoshio; Nomura, Masahiro

    1994-01-01

    An electron gun launching high average current beam has been designed for the high power CW electron linac at PNC. A peak electron beam current of 400mA with beam energy 200keV is required from the buncher design. However its average current is very high(duty factor 20%), a mesh grid is not able to be used for current control because of heating up or melting of grid. Furthermore, the beam current have to be variable up to 400mA to match with downstream modules, especially the accelerating guides including recirculating system. We employed the electron gun with two aperture grids to control beam current. The dimension of the electrodes, electron trajectory, the size of beam radius, and gun emittance was simulated by EGUN. (author)

  7. CW operation of high-power blue laser diodes with polished facets on semi-polar ( 20 2 ¯ 1 ¯ ) GaN substrates

    KAUST Repository

    Pourhashemi, A.; Farrell, R.M.; Cohen, D.A.; Becerra, D.L.; DenBaars, S.P.; Nakamura, S.

    2016-01-01

    Continuous wave (CW) operation of high-power blue laser diodes (LDs) with polished facets on semi-polar (202̅1̅) gallium nitride (GaN) substrates is demonstrated. Ridge waveguide LDs were fabricated using indium GaN waveguiding layers and GaN cladding layers. At a lasing wavelength of 452 nm, the peak two-facet CW output power from an LD with uncoated facets was 1.71 W at a current of 3 A, corresponding to an optical power density of 32.04 MW/cm2 on each facet. The dependence of output power on current did not change with repeated CW measurements, indicating that the polished facets did not degrade under high-power CW operation. These results show that polished facets are a viable alternative to cleaved or etched facets for high-power CW semi-polar LDs.

  8. CW operation of high-power blue laser diodes with polished facets on semi-polar ( 20 2 ¯ 1 ¯ ) GaN substrates

    KAUST Repository

    Pourhashemi, A.

    2016-10-11

    Continuous wave (CW) operation of high-power blue laser diodes (LDs) with polished facets on semi-polar (202̅1̅) gallium nitride (GaN) substrates is demonstrated. Ridge waveguide LDs were fabricated using indium GaN waveguiding layers and GaN cladding layers. At a lasing wavelength of 452 nm, the peak two-facet CW output power from an LD with uncoated facets was 1.71 W at a current of 3 A, corresponding to an optical power density of 32.04 MW/cm2 on each facet. The dependence of output power on current did not change with repeated CW measurements, indicating that the polished facets did not degrade under high-power CW operation. These results show that polished facets are a viable alternative to cleaved or etched facets for high-power CW semi-polar LDs.

  9. Production of High Intracavity UV Power From a CW Laser Source

    Science.gov (United States)

    David, R. T.; Chyba, T. H.; Keppel, C. E.; Gaskell, D.; Ent, R.

    1998-01-01

    The goal of this research project is to create a prototype high power CW source of ultraviolet (UV) photons for photon-electron scattering at the Thomas Jefferson National Accelerator Facility (TJNAF), Hall B. The facility will use optical resonant cavities to produce a high photon flux. The technical approach will be to frequency-double the 514.5 mn light from an Argon-Ion Laser to create 0.1 to 1.0 watt in the UV. The produced UV power will be stored in a resonant cavity to generate an high intracavity UV power of 102 to 103 watts. The specific aim of this project is to first design and construct the low-Q doubling cavity and lock it to the Argon-Ion wavelength. Secondly, the existing 514.5 nm high-Q build-up cavity and its locking electronics will be modified to create high intracavity UV power. The entire system will then be characterized and evaluated for possible beam line use.

  10. Complete indium-free CW 200W passively cooled high power diode laser array using double-side cooling technology

    Science.gov (United States)

    Wang, Jingwei; Zhu, Pengfei; Liu, Hui; Liang, Xuejie; Wu, Dihai; Liu, Yalong; Yu, Dongshan; Zah, Chung-en; Liu, Xingsheng

    2017-02-01

    High power diode lasers have been widely used in many fields. To meet the requirements of high power and high reliability, passively cooled single bar CS-packaged diode lasers must be robust to withstand thermal fatigue and operate long lifetime. In this work, a novel complete indium-free double-side cooling technology has been applied to package passively cooled high power diode lasers. Thermal behavior of hard solder CS-package diode lasers with different packaging structures was simulated and analyzed. Based on these results, the device structure and packaging process of double-side cooled CS-packaged diode lasers were optimized. A series of CW 200W 940nm high power diode lasers were developed and fabricated using hard solder bonding technology. The performance of the CW 200W 940nm high power diode lasers, such as output power, spectrum, thermal resistance, near field, far field, smile, lifetime, etc., is characterized and analyzed.

  11. Single-transverse-mode near-IR superluminescent diodes with cw output power up to 100 mW

    International Nuclear Information System (INIS)

    Andreeva, E V; Il'chenko, S N; Kostin, Yu O; Yakubovich, S D

    2014-01-01

    A series of light-emitting modules based on single-mode quantum-well superluminescent diodes with centre emission wavelengths of about 790, 840, 960 and 1060 nm and a cw output power up to 100 mW in free space is developed. A sufficiently long service life of these devices is demonstrated. (lasers)

  12. Single-transverse-mode near-IR superluminescent diodes with cw output power up to 100 mW

    Energy Technology Data Exchange (ETDEWEB)

    Andreeva, E V; Il' chenko, S N; Kostin, Yu O [Superlum Diodes Ltd., Moscow (Russian Federation); Yakubovich, S D [Moscow State Institute of Radio-Engineering, Electronics and Automation (Technical University), Moscow (Russian Federation)

    2014-10-29

    A series of light-emitting modules based on single-mode quantum-well superluminescent diodes with centre emission wavelengths of about 790, 840, 960 and 1060 nm and a cw output power up to 100 mW in free space is developed. A sufficiently long service life of these devices is demonstrated. (lasers)

  13. High-power pulsed and CW diode-pumped mode-locked Nd:YAG lasers

    Science.gov (United States)

    Marshall, Larry R.; Hays, A. D.; Kaz, Alex; Kasinski, Jeff; Burnham, R. L.

    1991-01-01

    The operation of both pulsed and CW diode-pumped mode-locked Nd:YAG lasers are presented. The pulsed laser produced 1.0 mJ with pulsewidths of 90 psec at 20 Hz. The CW pumped laser produced 6 W output at 1.064 microns and 3 W output at 532 nm.

  14. A computer control system for the PNC high power cw electron linac. Concept and hardware

    Energy Technology Data Exchange (ETDEWEB)

    Emoto, T.; Hirano, K.; Takei, Hayanori; Nomura, Masahiro; Tani, S. [Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center; Kato, Y.; Ishikawa, Y.

    1998-06-01

    Design and construction of a high power cw (Continuous Wave) electron linac for studying feasibility of nuclear waste transmutation was started in 1989 at PNC. The PNC accelerator (10 MeV, 20 mA average current, 4 ms pulse width, 50 Hz repetition) is dedicated machine for development of the high current acceleration technology in future need. The computer control system is responsible for accelerator control and supporting the experiment for high power operation. The feature of the system is the measurements of accelerator status simultaneously and modularity of software and hardware for easily implemented for modification or expansion. The high speed network (SCRAM Net {approx} 15 MB/s), Ethernet, and front end processors (Digital Signal Processor) were employed for the high speed data taking and control. The system was designed to be standard modules and software implemented man machine interface. Due to graphical-user-interface and object-oriented-programming, the software development environment is effortless programming and maintenance. (author)

  15. A Novel Ku-Band/Ka-Band and Ka-Band/E-Band Multimode Waveguide Couplers for Power Measurement of Traveling-Wave Tube Amplifier Harmonic Frequencies

    Science.gov (United States)

    Wintucky, Edwin G.; Simons, Rainee N.

    2015-01-01

    This paper presents the design, fabrication and test results for a novel waveguide multimode directional coupler (MDC). The coupler, fabricated from two dissimilar frequency band waveguides, is capable of isolating power at the second harmonic frequency from the fundamental power at the output port of a traveling-wave tube (TWT) amplifier. Test results from proof-of-concept demonstrations are presented for a Ku-band/Ka-band MDC and a Ka-band/E-band MDC. In addition to power measurements at harmonic frequencies, a potential application of the MDC is in the design of a satellite borne beacon source for atmospheric propagation studies at millimeter-wave (mm-wave) frequencies (Ka-band and E-band).

  16. Design of planar electron gun for UHF range, CW power inductive output tube

    International Nuclear Information System (INIS)

    Kaushik, Meenu; Joshi, L.M.

    2015-01-01

    Inductive Output Tube (lOT) is an amplifier which is now-a-days in demand for scientific applications. For every vacuum tube, electron gun is an important part and in fact considered as the heart of the tube. Hence, designing of this component is very crucial for efficient operation of the device throughout its lifetime. This paper is all about the electromagnetic (EM) design of planar electron gun of 40 kV, 3.5 A beam voltage and beam current respectively, for a 100 kW CW power lOT operating in UHF range. The design considerations and basic equations involved in its design are included in the paper. The gun structure has been optimized for getting the desired beam characteristics. The simulation results including the beam profile along with the beam current are shown using two commercial codes namely TRAK and MAGIC code. Planar shape of electron beam reduces space charge forces in the beam itself and consequently beam energy spread for a given current. The magnetic focusing of planar beam is easier comparative to spherical beam hence, this structure has been adopted for this particular device design. (author)

  17. Gain measurement in a CW medium-power diode pumped Nd:YAG laser amplifier by ASE analysis

    International Nuclear Information System (INIS)

    Razzaghi, D; Hajiesmaeilbaigi, F; Ruzbehani, M

    2014-01-01

    Using the relation between amplified spontaneous emission intensity and gain, a set of formulas is derived for gain evaluation by comparing fluorescence yield in two different lengths of the active medium. Experimental measurements are carried out and gain is calculated by solving the derived formula. For comparison, measurements are also carried out using the probe beam method, which shows good agreement between the two methods in a typical CW medium-power diode pumped Nd:YAG amplifier. (paper)

  18. Application of M-type cathodes to high-power cw klystrons

    Science.gov (United States)

    Isagawa, S.; Higuchi, T.; Kobayashi, K.; Miyake, S.; Ohya, K.; Yoshida, M.

    1999-05-01

    Two types of high-power cw klystrons have been widely used at KEK in both TRISTAN and KEKB e +e - collider projects: one is a 0.8 MW/1.0 MW tube, called YK1302/YK1303 (Philips); the other is a 1.2 MW tube, called E3786/E3732 (Toshiba). Normally, the dispenser cathodes of the `B-type' and the `S-type' have been used, respectively, but for improved versions they have been replaced by low-temperature cathodes, called the `M-type'. An Os/Ru coating was applied to the former, whereas an Ir one was applied to the latter. Until now, all upgraded tubes installing M-type cathodes, 9 and 8 in number, respectively, have worked successfully without any dropout. A positive experience concerning the lifetime under real operation conditions has been obtained. M-type cathodes are, however, more easily poisoned. One tube installing an Os/Ru-coated cathode showed a gradual, and then sudden decrease in emission during an underheating test, although the emission could fortunately be recovered by aging at the KEK test field. Once sufficiently aged, the emission of an Ir-coated cathode proved to be very high and stable, and its lifetime is expected to be very long. One disadvantage of this cathode is, however, susceptibility to gas poisoning and the necessity of long-term initial aging. New techniques, like ion milling and fine-grained tungsten top layers, were not as successful as expected from their smaller scale applications to shorten the initial aging period. A burn-in process at higher cathode loading was efficient to make the poisoned cathode active and to decrease unwanted Wehnelt emission. On top of that, the emission cooling, and thus thermal conductivity near the emitting layer could play an important role in such large-current cathodes as ours.

  19. 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.

  20. Power-scalable, polarization-stable, dual-colour DFB fibre laser system for CW terahertz imaging

    DEFF Research Database (Denmark)

    Eichhorn, Finn; Pedersen, Jens Engholm; Jepsen, Peter Uhd

    Imaging with electromagnetic radiation in the terahertz (THz) range has received a large amount of attention during recent years. THz imaging systems have diverse potential application areas such as security screening, medical diagnostics and non-destructive testing. We will discuss a power......-scalable, dual-colour, polarization-maintaining distributed feedback (DFB) fibre laser system with an inherent narrow linewidth from the DFB fibre laser oscillators. The laser system can be used as source in CW THz systems employing photomixing (optical heterodyning) for generation and detection...

  1. rf coupler technology for fusion applications

    International Nuclear Information System (INIS)

    Hoffman, D.J.

    1983-01-01

    Radio frequency (rf) oscillations at critical frequencies have successfully provided a means to convey power to fusion plasmas due to the electrical-magnetic properties of the plasma. While large rf systems to couple power to the plasma have been designed, built, and tested, the main link to the plasma, the coupler, is still in an evolutionary stage of development. Design and fabrication of optimal antennas for fusion applications are complicated by incomplete characterizations of the harsh plasma environment and of coupling mechanisms. A brief description of rf coupler technology required for plasma conditions is presented along with an assessment of the status and goals of coupler development

  2. Design of the 3.7 GHz, 500 kW CW circulator for the LHCD system of the SST-1 tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Dixit, Harish V., E-mail: hvdixit48@yahoo.com [Veermata Jijabai Technological Institute, Mumbai, Maharashtra 400019 (India); Jadhav, Aviraj R. [Veermata Jijabai Technological Institute, Mumbai, Maharashtra 400019 (India); Jain, Yogesh M. [Institute for Plasma Research, Gandhinagar, Gujarat 382428 (India); Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094 (India); Cheeran, Alice N. [Veermata Jijabai Technological Institute, Mumbai, Maharashtra 400019 (India); Gupta, Vikas [Vidyavardhini' s College of Engineering and Technology, Vasai, Maharashtra 401202 (India); Sharma, P.K. [Institute for Plasma Research, Gandhinagar, Gujarat 382428 (India); Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094 (India)

    2017-06-15

    Highlights: • Design of a 500 kW CW circulator for LHCD system at 3.7 GHz. • Mechanism for thermal management of ferrite tile. • Scheme for uniform magnetisation of the ferrite tiles. • Design of high CW power CW quadrature and 180 ° hybrid coupler. - Abstract: Circulators are used in high power microwave systems to protect the vacuum source against reflection. The Lower Hybrid Current Drive (LHCD) system of SST-1 tokamak commissioned at IPR, Gandhinagar in India comprises of four high power circulators to protect klystrons (supplying 500 kW CW each at 3.7 GHz) which power the system. This paper presents the design of a Differential Phase Shift Circulator (DPSC) capable of handling 500 kW CW power at 3.7 GHz so that four circulators can be used to protect the four available klystrons. As the DPSC is composed by three main components, viz., magic tee, ferrite phase shifter and 3 dB hybrid coupler, the designing of each of the proposed components is described. The design of these components is carried out factoring various multiphysics aspects of RF, heating due to high CW power and magnetic field requirement of the ferrite phase shifter. The primary objective of this paper is to present the complete RF, magnetic and thermal design of a high CW power circulator. All the simulations have been carried out in COMSOL Multiphysics. The designed circulator exhibits an insertion loss of 0.13 dB with a worst case VSWR of 1.08:1. The total length of the circulator is 3 m.

  3. Polarization converted coupler for plasma current drive experiments

    International Nuclear Information System (INIS)

    Arai, H.; Shimizu, S.; Goto, N.

    1986-01-01

    In this paper, the authors propose the polarization converted coupler which has narrow width shape and radiates electric field perpendicular to the main toroidal magnetic field. The advantages of the polarization converted coupler are as follows: (l) The rectangular waveguide as the transmission line has the high power capability. (2) The all metal design is not damaged by the fusion neutron. (3) The characteristic of this coupler is not changed widely, since the coupler has the matching section. For example, the VSWR of its input impedance is less than 2.0 for both water and air load. The authors present characteristics of the polarization converted coupler measured by the model experiments

  4. Novel packaging for CW and QCW diode laser modules for operation with high power and duty cycles

    Science.gov (United States)

    Fassbender, Wilhelm; Lotz, Jens; Kissel, Heiko; Biesenbach, Jens

    2018-02-01

    Continuous wave (CW) and quasi-continuous wave (QCW) operated diode laser bars and arrays have found a wide range of industrial, medical, scientific, military and space applications with a broad variety in wavelength, pulse energy, pulse duration and beam quality. Recent applications require even higher power, duty cycles and power density. The heat loss will be dissipated by conductive cooling or liquid cooling close to the bars. We present the latest performance and reliability data of two novel high-brightness CW and QCW arrays of customized and mass-production modules, in compact and robust industry design for operation with high power and high duty cycles. All designs are based on single diode packages consisting of 10mm laser bars, soft or hard soldered between expansion matched submounts. The modular components cover a wide span of designs which differ basically in water/conduction (active/passive) cooled, single, linear (horizontal and vertical) arranged designs, as well as housed and unhoused modules. The different assembling technologies of active and passive cooled base plates affect the heat dissipation and therefore the reachable power at different QCW operating conditions, as well as the lifetime. As an example, a package consisting of 8 laser diodes, connected to a 28.8*13.5*7.0mm3 DCB (direct copper bonded) submount, passively or actively cooled is considered. This design is of particular interest for mobile applications seamless module to module building system, with an infinite number of laser bars at 1.7mm pitch. Using 940nm bars we can reach an optical output power per bar of 450W at 25°C base plate temperature with 10Hz, 1.2% duty cycle and 1.2ms pulse duration. As an additional example, micro channel coolers can be vertically stacked up to 50 diodes with a 1,15mm pitch. This design is suitable for all applications, demanding also compactness and light weight and high power density. Using near infrared bars and others, we can reach an optical

  5. High-power cw laser bars of the 750 – 790-nm wavelength range

    International Nuclear Information System (INIS)

    Degtyareva, N S; Kondakov, S A; Mikayelyan, G T; Gorlachuk, P V; Ladugin, M A; Marmalyuk, Aleksandr A; Ryaboshtan, Yu L; Yarotskaya, I V

    2013-01-01

    We have developed the effective design of semiconductor heterostructures, which allow one to fabricate cw laser diodes emitting in the 750 – 790-nm spectral range. The optimal conditions for fabrication of GaAsP/AlGaInP/GaAs heterostructures by MOCVD have been determined. It is shown that the use of quantum wells with a precisely defined quantity mismatch reduces the threshold current density and increases the external differential efficiency. The results of studies of characteristics of diode laser bars fabricated from these heterostructures are presented. (lasers)

  6. Development of high power CW and pulsed RF test facility based on 1 MW, 352.2 MHz klystron amplifier

    International Nuclear Information System (INIS)

    Badapanda, M.K.; Tripathi, Akhilesh; Upadhyay, Rinki; Rao, J.N.; Tiwari, Ashish; Jain, Akhilesh; Lad, M.R.; Hannurkar, P.R.

    2013-01-01

    A high power 1 MW, 352.2 MHz RF Test facility having CW and Pulse capability is being developed at Raja Ramanna Centre for Advanced Technology (RRCAT), Indore for performance evaluation of various RF components, accelerating structures and related subsystems. Thales make 1 MW, 352.2 MHz klystron amplifier (TH 2089) will be employed in this high power test facility, which is thoroughly tested for its performance parameters at rated operating conditions. Auxiliary power supplies like filament, electromagnet, ion pump and mod anode power supply as well as 200 W solid state driver amplifier necessary for this high power test facility have been developed. A high voltage floating platform is created for floating filament and mod anode power supplies. Interconnection of various power supplies and other subsystems of this test facility are being carried out. A high voltage 100 kV, 25 Amp DC crowbar less power supply and low conductivity water (LCW) plant required for this klystron amplifier are in advanced stage of development. NI make cRIO 9081 real time (RT) controller based control and interlock system has been developed to realize proper sequence of operation of various power supplies and to monitor the status of crucial parameters in this test facility. This RF test facility will provide confidence for development of RF System of future accelerators like SNS and ADSS. (author)

  7. Survey on neutron production by electron beam from high power CW electron linear accelerator

    International Nuclear Information System (INIS)

    Toyama, S.

    1999-04-01

    In Japan Nuclear Cycle Development Institute, the development of high current CW electron linear accelerator is in progress. It is possible for an accelerator to produce neutrons by means of a spallation and photo nuclear reactions. Application of neutron beam produced by bremsstrahlung is one of ways of the utilization for high current electron accelerator. It is actual that many electron linear accelerators which maximum energy is higher than a few hundreds MeV are used as neutron sources. In this report, an estimate of neutron production is evaluated for high current CW electron linear accelerator. The estimate is carried out by 10 MeV beam which is maximum energy limited from the regulation and rather low for neutron production. Therefore, the estimate is also done by 17 and 35 MeV beam which is possible to be accelerated. Beryllium is considered as a target for lower electron energy in addition to Lead target for higher energy, because Beryllium has low threshold energy for neutron production. The evaluation is carried out in account of the target thickness optimized by the radiation length and neutron cross section reducing the energy loss for both of electron and neutron, so as to get the maximum number of neutrons. The result of the calculations shows neutron numbers 1.9 x 10 10 , 6.1 x 10 13 and 4.8 x 10 13 (n/s), respectively, for 10, 17, and 35 MeV with low duty. The thermal removal from the target is one of critical points. The additional shielding and cooling system is necessary in order to endure radiation. A comparison with other facilities are also carried out. The estimate of neutron numbers suggests the possibility to be applied for neutron radiography and measurement of nuclear data by means of Lead spectrometer, for example. (author)

  8. High-power CW and long-pulse lasers in the green wavelength regime for copper welding

    Science.gov (United States)

    Pricking, Sebastian; Huber, Rudolf; Klausmann, Konrad; Kaiser, Elke; Stolzenburg, Christian; Killi, Alexander

    2016-03-01

    We report on industrial high-power lasers in the green wavelength regime. By means of a thin disk oscillator and a resonator-internal nonlinear crystal for second harmonic generation we are able to extract up to 8 kW pulse power in the few-millisecond range at a wavelength of 515 nm with a duty cycle of 10%. Careful shaping and stabilization of the polarization and spectral properties leads to a high optical-to-optical efficiency larger than 55%. The beam parameter product is designed and measured to be below 5 mm·mrad which allows the transport by a fiber with a 100 μm core diameter. The fiber and beam guidance optics are adapted to the green wavelength, enabling low transmission losses and stable operation. Application tests show that this laser is perfectly suited for copper welding due to the superior absorption of the green wavelength compared to IR, which allows us to produce weld spots with an unprecedented reproducibility in diameter and welding depth. With an optimized set of parameters we could achieve a splatter-free welding process of copper, which is crucial for welding electronic components. Furthermore, the surface condition does not influence the welding process when the green wavelength is used, which allows to skip any expensive preprocessing steps like tin-coating. With minor changes we could operate the laser in cw mode and achieved up to 1.7 kW of cw power at 515 nm with a beam parameter product of 2.5 mm·mrad. These parameters make the laser perfectly suitable for additional applications such as selective laser melting of copper.

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

    International Nuclear Information System (INIS)

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

    2005-01-01

    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

  10. Development of an electron gun for high power CW electron linac (1). Beam experiment for basic performance of electron gun

    International Nuclear Information System (INIS)

    Yamazaki, Yoshio; Nomura, Masahiro; Komata, Tomoki

    1999-05-01

    Presently, the Beam Group of Oarai Engineering Center in Japan Nuclear Cycle Development Institute (JNC) completed the high power CW electron linac. Then we started full-scale beam experiments after the government permission for a radiation equipment had given last January. Measurements of basic performance for the mesh-grid type electron gun have been done to launch stable beam at 300 mA peak current downstream of the accelerator. These experiments disclosed to increase beam loss in the electron gun in some cases of voltage supplied the mesh-grid in spite of same beam current from gun. Consequently, we could find the best condition for mesh-grid voltage and heater current to supply stable beam at 300 mA peak current for accelerator study. (author)

  11. Terraced-heterostructure large-optical-cavity AlGaAs diode laser - A new type of high-power CW single-mode device

    Science.gov (United States)

    Botez, D.; Connolly, J. C.

    1982-01-01

    A new terraced lateral wave confining structure is obtained by liquid phase epitaxy over channeled substrates misoriented perpendicular to the channels' direction. Single spatial and longitudinal mode CW operation is achieved to 50 mW from one facet, in large spot sizes (2 x 7.5 micron, 1/e squared points in intensity) and narrow beams (6 deg x 23 deg), full width half-power). At 70 C ambient temperature CW lasing is obtained to 15 mW from one facet. Weak mode confinement in an asymmetric lateral waveguides provides discrimination against high-order mode oscillation.

  12. 11-GHz waveguide Nd:YAG laser CW mode-locked with single-layer graphene.

    Science.gov (United States)

    Okhrimchuk, Andrey G; Obraztsov, Petr A

    2015-06-08

    We report stable, passive, continuous-wave (CW) mode-locking of a compact diode-pumped waveguide Nd:YAG laser with a single-layer graphene saturable absorber. The depressed cladding waveguide in the Nd:YAG crystal is fabricated with an ultrafast laser inscription method. The saturable absorber is formed by direct deposition of CVD single-layer graphene on the output coupler. The few millimeter-long cavity provides generation of 16-ps pulses with repetition rates in the GHz range (up to 11.3 GHz) and 12 mW average power. Stable CW mode-locking operation is achieved by controlling the group delay dispersion in the laser cavity with a Gires-Tournois interferometer.

  13. Thermal Investigation of Interaction between High-power CW-laser Radiation and a Water-jet

    Science.gov (United States)

    Brecher, Christian; Janssen, Henning; Eckert, Markus; Schmidt, Florian

    The technology of a water guided laser beam has been industrially established for micro machining. Pulsed laser radiation is guided via a water jet (diameter: 25-250 μm) using total internal reflection. Due to the cylindrical jet shape the depth of field increases to above 50 mm, enabling parallel kerfs compared to conventional laser systems. However higher material thicknesses and macro geometries cannot be machined economically viable due to low average laser powers. Fraunhofer IPT has successfully combined a high-power continuous-wave (CW) fiber laser (6 kW) and water jet technology. The main challenge of guiding high-power laser radiation in water is the energy transferred to the jet by absorption, decreasing its stability. A model of laser water interaction in the water jet has been developed and validated experimentally. Based on the results an upscaling of system technology to 30 kW is discussed, enabling a high potential in cutting challenging materials at high qualities and high speeds.

  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. Cryogenic cooler thermal coupler

    International Nuclear Information System (INIS)

    Green, K.E.; Talbourdet, J.A.

    1984-01-01

    A thermal coupler assembly mounted to the coldfinger of a cryogenic cooler which provides improved thermal transfer between the coldfinger and the detector assembly mounted on the dewar endwell. The thermal coupler design comprises a stud and spring-loaded cap mounted on the coldfinger assembly. Thermal transfer is made primarily through the air space between the cap and coldwell walls along the radial surfaces. The cap is spring loaded to provide thermal contact between the cap and endwell end surfaces

  16. MAFIA simulation and cold model test of three types of bridge coupler

    International Nuclear Information System (INIS)

    Chang, C.R.; Yao, C.G.; Swenson, D.A.; Funk, L.W.; Raparia, D.

    1992-01-01

    In the new design of the SSC CCL, the total number of bridge couplers has increased from 50 to 63, and their maximum length increased from 37.2 to 46.1 cm. Choosing a bridge coupler that gives maximum coupling, minimum power flow, phase shift and fabrication cost becomes important. The conventional TM010 single cavity bridge coupler used in LAMPF and Fermilab will have severe mode mixing problem when the bridge length is over 30 cm, and the coupling is very weak. Three types of bridge coupler have been proposed: (1) TM012 single cavity bridge coupler; (2) electrically coupled multi-cavity bridge coupler and (3) magnetically coupled multi-cavity bridge coupler. This paper presents both MAFIA simulations and cold model tests results. Each bridge coupler has its unique characteristics with advantages and disadvantages, but all three are superior to the conventional coupler. (Author) 6 figs., tab., 2 refs

  17. Outgassing studies of lower hybrid antenna module during CW high RF power injection

    International Nuclear Information System (INIS)

    Goniche, M.; Brossaud, J.; Berger-By, G.; Bibet, Ph.; Poli, S.; Rey, G.; Tonon, G.; Seki, M.; Obara, K.; Maebara, S.; Ikeda, Y.; Imai, T.; Nagashima, T.

    1994-01-01

    Outgassing, induced by very long RF waves injection (up to 6000s) at high power density, is studied with a module, able to be used for a lower hybrid frequency antenna. A large outgassing data base is provided by 75 shots cumulating 27 hours of RF injection. Outgassing rate is documented after different thermal pre-treatments, and in various conditions of cooling, RF power level. Relevant parameters are identified and values of outgassing rates are given in order to design pumping system for a large antenna. (author) 4 refs.; 7 figs.; 1 tab

  18. Reliability aspects and facet damage in high-power emission from (AlGa)As cw laser diodes at room temperature

    International Nuclear Information System (INIS)

    Kressel, H.; Ladany, I.

    1975-01-01

    Factors are described that limit the optical power output from (AlGa)As laser diodes (lambda = 8100 to 8300 A) operating cw at room temperature with uncoated facets. Rapid laser ''catastrophic'' degradation due to facet damage (in contrast to ''bulk'' phenomena previously considered) has been found to occur as a result of excessive optical flux density at the facets. The diodes studied are capable of initial cw power emission values of 25 to 100 mW from one facet depending on their dimensions. Data are presented showing long-term constant-current operation at power levels below these maximum values. Preliminary data are also presented on devices utilizing dielectric facet coatings to minimize facet damage. (U.S.)

  19. High power CW output from low confinement asymmetric structure diode laser

    NARCIS (Netherlands)

    Iordache, G.; Buda, M.; Acket, G.A.; Roer, van de T.G.; Kaufmann, L.M.F.; Karouta, F.; Jagadish, C.; Tan, H.H.

    1999-01-01

    High power continuous wave output from diode lasers using low loss, low confinement, asymmetric structures is demonstrated. An asymmetric structure with an optical trap layer was grown by metal organic vapour phase epitaxy. Gain guided 50 µm wide stripe 1-3 mm long diode lasers were studied. 1.8 W

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

    Science.gov (United States)

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

    2004-01-01

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

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

    Science.gov (United States)

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

    2006-01-01

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

  2. Ion cyclotron resonance heating systems upgrade toward high power and CW operations in WEST

    Energy Technology Data Exchange (ETDEWEB)

    Hillairet, Julien, E-mail: julien.hillairet@cea.fr; Mollard, Patrick; Bernard, Jean-Michel; Argouarch, Arnaud; Berger-By, Gilles; Charabot, Nicolas; Colas, Laurent; Delaplanche, Jean-Marc; Ekedahl, Annika; Fedorczak, Nicolas; Ferlay, Fabien; Goniche, Marc; Hatchressian, Jean-Claude; Helou, Walid; Jacquot, Jonathan; Joffrin, Emmanuel; Litaudon, Xavier; Lombard, Gilles; Magne, Roland; Patterlini, Jean-Claude [CEA, IRFM, F-13108 Saint Paul-lez-Durance (France); and others

    2015-12-10

    The design of the WEST (Tungsten-W Environment in Steady-state Tokamak) Ion cyclotron resonance heating antennas is based on a previously tested conjugate-T Resonant Double Loops prototype equipped with internal vacuum matching capacitors. The design and construction of three new WEST ICRH antennas are being carried out in close collaboration with ASIPP, within the framework of the Associated Laboratory in the fusion field between IRFM and ASIPP. The coupling performance to the plasma and the load-tolerance have been improved, while adding Continuous Wave operation capability by introducing water cooling in the entire antenna. On the generator side, the operation class of the high power tetrodes is changed from AB to B in order to allow high power operation (up to 3 MW per antenna) under higher VSWR (up to 2:1). Reliability of the generators is also improved by increasing the cavity breakdown voltage. The control and data acquisition system is also upgraded in order to resolve and react on fast events, such as ELMs. A new optical arc detection system comes in reinforcement of the V{sub r}/V{sub f} and SHAD systems.

  3. A sweep plate emittance scanner for high-power CW ion beams

    International Nuclear Information System (INIS)

    Debiak, T.W.; Ng, Y.; Sredniawski, J.; Stasi, W.

    1996-01-01

    Sweep plate scanners are preferred for emittance measurement due to their versatility, simplicity, and precision. At the Advanced Technology and Development Center of Northrop Grumman, we have routinely used these devices for characterization of injector beams with less than 20 W/cm 2 average power density. To characterize higher power beams, like those required for production of tritium or for radioactive waste transmutation, the scanner pod and data collection algorithm must be redesigned due to the possibility of melting the scanner's protective front face or distorting the precision entrance knife edges. Among the methods we have used to mitigate these effects, one consists of drastically reducing the amount of time required for data collection. In this method, the emittance scanner pod traverses the beam in two passes, each requiring less than 0.5 second. In the first pass, the phase space limits of the beam are determined. In the second pass, data is collected primarily within the phase space region limits determined in the first pass. In this way, enough points are collected to assure that the precision of the measurement is high, even though the data collection time for each scan is less than 0.5 second. This paper will describe the layout of the scanner components, the data collection electronics and algorithm, and the data analysis. (author)

  4. High average power CW FELs [Free Electron Laser] for application to plasma heating: Designs and experiments

    International Nuclear Information System (INIS)

    Booske, J.H.; Granatstein, V.L.; Radack, D.J.; Antonsen, T.M. Jr.; Bidwell, S.; Carmel, Y.; Destler, W.W.; Latham, P.E.; Levush, B.; Mayergoyz, I.D.; Zhang, Z.X.

    1989-01-01

    A short period wiggler (period ∼ 1 cm), sheet beam FEL has been proposed as a low-cost source of high average power (1 MW) millimeter-wave radiation for plasma heating and space-based radar applications. Recent calculation and experiments have confirmed the feasibility of this concept in such critical areas as rf wall heating, intercepted beam (''body'') current, and high voltage (0.5 - 1 MV) sheet beam generation and propagation. Results of preliminary low-gain sheet beam FEL oscillator experiments using a field emission diode and pulse line accelerator have verified that lasing occurs at the predicted FEL frequency. Measured start oscillation currents also appear consistent with theoretical estimates. Finally, we consider the possibilities of using a short-period, superconducting planar wiggler for improved beam confinement, as well as access to the high gain, strong pump Compton regime with its potential for highly efficient FEL operation

  5. Enhancement of thermal blooming effect on free space propagation of high power CW laser beam

    Science.gov (United States)

    Kashef, Tamer M.; Mokhtar, Ayman M.; Ghoniemy, Samy A.

    2018-02-01

    In this paper, we present an enhanced model to predict the effect of thermal blooming and atmospheric turbulence, on high energy laser beams free space propagation. We introduce an implementation technique for the proposed mathematical models describing the effect of thermal blooming and atmospheric turbulence including wind blowing, and how it effect high power laser beam power, far field pattern, phase change effect and beam quality . An investigated model of adaptive optics was introduced to study how to improve the wave front and phase distortion caused by thermal blooming and atmospheric turbulence, the adaptive optics model with Actuator influence spacing 3 cm the that shows observed improvement in the Strehl ratio and in wave front and phase of the beam. These models was implemented using cooperative agents relying on GLAD software package. Without taking in consideration the effect of thermal blooming It was deduced that the beam at the source takes the Gaussian shape with uniform intensity distribution, we found that the beam converge on the required distance 4 km using converging optics, comparing to the laser beam under the effect of thermal blooming the far field pattern shows characteristic secondary blip and "sugar scoop" effect which is characteristic of thermal blooming. It was found that the thermal blooming causes the beam to steer many centimeters and to diverge beyond about 1.8 km than come to a focus at 4 km where the beam assumed to be focused on the required target. We assume that this target is moving at v = (4,-4) m/sec at distance 4 km and the wind is moving at v = (-10,-10) m/sec, it was found that the effect will be strongest when wind and target movement are at the same velocity. GLAD software is used to calculate the attenuation effects of the atmosphere as well as the phase perturbations due to temperature change in the air and effects caused as the beam crosses through the air due to wind and beam steering.

  6. Ultrashort hybrid metal-insulator plasmonic directional coupler.

    Science.gov (United States)

    Noghani, Mahmoud Talafi; Samiei, Mohammad Hashem Vadjed

    2013-11-01

    An ultrashort plasmonic directional coupler based on the hybrid metal-insulator slab waveguide is proposed and analyzed at the telecommunication wavelength of 1550 nm. It is first analyzed using the supermode theory based on mode analysis via the transfer matrix method in the interaction region. Then the 2D model of the coupler, including transition arms, is analyzed using a commercial finite-element method simulator. The hybrid slab waveguide is composed of a metallic layer of silver and two dielectric layers of silica (SiO2) and silicon (Si). The coupler is optimized to have a minimum coupling length and to transfer maximum power considering the layer thicknesses as optimization variables. The resulting coupling length in the submicrometer region along with a noticeable power transfer efficiency are advantages of the proposed coupler compared to previously reported plasmonic couplers.

  7. High output power of differently cut Nd:MgO:LiTaO3 CW lasers

    Science.gov (United States)

    Sun, D. H.; Liu, S. D.; Wang, D. Z.; Sang, Y. H.; Kang, X. L.; Liu, H.; Bi, Y.; Yan, B. X.; He, J. L.; Wang, J. Y.

    2013-04-01

    A high-quality Nd3+ and Mg2+ co-doped LiTaO3 (Nd:MgO:LT) crystal was grown by the Czochralski method. The polarized absorption spectra and fluorescence spectra were studied, and the absorption cross section was calculated by Judd-Ofelt (J-O) theory. The laser performance with different sample cuts of the crystal was investigated for the first time, and it was found that Nd:MgO:LT crystal with different cutting directions (a and c) exhibits different laser properties. By optimizing a partial reflectivity mirror in the laser experimental setting, a high continuous wave output power of 3.58 W was obtained at 1092 and 1076 nm with an optical-to-optical conversion efficiency of 22.78% and slope efficiency of 26.06%. The results indicate that Nd:MgO:LT crystal is a promising candidate for the manufacture of Nd3+ doped periodically poled MgO:LiTaO3 crystal (Nd:PPMgOLT), which should have considerable applications in self-frequency doubling and optical parametric oscillation laser devices.

  8. High output power of differently cut Nd:MgO:LiTaO3 CW lasers

    International Nuclear Information System (INIS)

    Sun, D H; Liu, S D; Wang, D Z; Sang, Y H; Kang, X L; Liu, H; He, J L; Wang, J Y; Bi, Y; Yan, B X

    2013-01-01

    A high-quality Nd 3+ and Mg 2+ co-doped LiTaO 3 (Nd:MgO:LT) crystal was grown by the Czochralski method. The polarized absorption spectra and fluorescence spectra were studied, and the absorption cross section was calculated by Judd–Ofelt (J–O) theory. The laser performance with different sample cuts of the crystal was investigated for the first time, and it was found that Nd:MgO:LT crystal with different cutting directions (a and c) exhibits different laser properties. By optimizing a partial reflectivity mirror in the laser experimental setting, a high continuous wave output power of 3.58 W was obtained at 1092 and 1076 nm with an optical-to-optical conversion efficiency of 22.78% and slope efficiency of 26.06%. The results indicate that Nd:MgO:LT crystal is a promising candidate for the manufacture of Nd 3+ doped periodically poled MgO:LiTaO 3 crystal (Nd:PPMgOLT), which should have considerable applications in self-frequency doubling and optical parametric oscillation laser devices. (paper)

  9. Design of the 1.5 MW, 30-96 MHz ultra-wideband 3 dB high power hybrid coupler for Ion Cyclotron Resonance Frequency (ICRF) heating in fusion grade reactor

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Rana Pratap, E-mail: ranayadav97@gmail.com; Kumar, Sunil; Kulkarni, S. V. [Thapar University, Patiala, Punjab 147004, India and Institute for Plasma Research, Gandhinagar 382428 (India)

    2016-01-15

    Design and developmental procedure of strip-line based 1.5 MW, 30-96 MHz, ultra-wideband high power 3 dB hybrid coupler has been presented and its applicability in ion cyclotron resonance heating (ICRH) in tokamak is discussed. For the high power handling capability, spacing between conductors and ground need to very high. Hence other structural parameters like strip-width, strip thickness coupling gap, and junction also become large which can be gone upto optimum limit where various constrains like fabrication tolerance, discontinuities, and excitation of higher TE and TM modes become prominent and significantly deteriorates the desired parameters of the coupled lines system. In designed hybrid coupler, two 8.34 dB coupled lines are connected in tandem to get desired coupling of 3 dB and air is used as dielectric. The spacing between ground and conductors are taken as 0.164 m for 1.5 MW power handling capability. To have the desired spacing, each of 8.34 dB segments are designed with inner dimension of 3.6 × 1.0 × 40 cm where constraints have been significantly realized, compensated, and applied in designing of 1.5 MW hybrid coupler and presented in paper.

  10. Observation of snowfall with a low-power FM-CW K-band radar (Micro Rain Radar)

    Science.gov (United States)

    Kneifel, Stefan; Maahn, Maximilian; Peters, Gerhard; Simmer, Clemens

    2011-06-01

    Quantifying snowfall intensity especially under arctic conditions is a challenge because wind and snow drift deteriorate estimates obtained from both ground-based gauges and disdrometers. Ground-based remote sensing with active instruments might be a solution because they can measure well above drifting snow and do not suffer from flow distortions by the instrument. Clear disadvantages are, however, the dependency of e.g. radar returns on snow habit which might lead to similar large uncertainties. Moreover, high sensitivity radars are still far too costly to operate in a network and under harsh conditions. In this paper we compare returns from a low-cost, low-power vertically pointing FM-CW radar (Micro Rain Radar, MRR) operating at 24.1 GHz with returns from a 35.5 GHz cloud radar (MIRA36) for dry snowfall during a 6-month observation period at an Alpine station (Environmental Research Station Schneefernerhaus, UFS) at 2,650 m height above sea level. The goal was to quantify the potential and limitations of the MRR in relation to what is achievable by a cloud radar. The operational MRR procedures to derive standard radar variables like effective reflectivity factor ( Z e) or the mean Doppler velocity ( W) had to be modified for snowfall since the MRR was originally designed for rain observations. Since the radar returns from snowfall are weaker than from comparable rainfall, the behavior of the MRR close to its detection threshold has been analyzed and a method is proposed to quantify the noise level of the MRR based on clear sky observations. By converting the resulting MRR- Z e into 35.5 GHz equivalent Z e values, a remaining difference below 1 dBz with slightly higher values close to the noise threshold could be obtained. Due to the much higher sensitivity of MIRA36, the transition of the MRR from the true signal to noise can be observed, which agrees well with the independent clear sky noise estimate. The mean Doppler velocity differences between both radars

  11. High-power narrow-linewidth quasi-CW diode-pumped TEM00 1064 nm Nd:YAG ring laser.

    Science.gov (United States)

    Liu, Yuan; Wang, Bao-shan; Xie, Shi-yong; Bo, Yong; Wang, Peng-yuan; Zuo, Jun-wei; Xu, Yi-ting; Xu, Jia-lin; Peng, Qin-jun; Cui, Da-fu; Xu, Zu-yan

    2012-04-01

    We demonstrated a high average power, narrow-linewidth, quasi-CW diode-pumped Nd:YAG 1064 nm laser with near-diffraction-limited beam quality. A symmetrical three-mirror ring cavity with unidirectional operation elements and an etalon was employed to realize the narrow-linewidth laser output. Two highly efficient laser modules and a 90° quartz rotator for birefringence compensation were used for the high output power. The maximum average output power of 62.5 W with the beam quality factor M(2) of 1.15 was achieved under a pump power of 216 W at a repetition rate of 500 Hz, corresponding to the optical-to-optical conversion efficiency of 28.9%. The linewidth of the laser at the maximum output power was measured to be less than 0.2 GHz.

  12. Free electron laser variable bridge coupler

    International Nuclear Information System (INIS)

    Spalek, G.; Billen, J.H.; Garcia, J.A.; McMurry, D.E.; Harnsborough, L.D.; Giles, P.M.; Stevens, S.B.

    1985-01-01

    The Los Alamos free-electron laser (FEL) is being modified to test a scheme for recovering most of the power in the residual 20-MeV electron beam by decelerating the microbunches in a linear standing-wave accelerator and using the recovered energy to accelerate new beam. A variable-coupler low-power model that resonantly couples the accelerator and decelerator structures has been built and tested. By mixing the TE 101 and TE 102 modes, this device permits continuous variation of the decelerator fields relative to the accelerator fields through a range of 1:1 to 1:2.5. Phase differences between the two structures are kept below 1 0 and are independent of power-flow direction. The rf power is also fed to the two structures through this coupling device. Measurements were also made on a three-post-loaded variable coupler that is a promising candidate for the same task

  13. Time-Domain Simulation of RF Couplers

    International Nuclear Information System (INIS)

    Smithe, David; Carlsson, Johan; Austin, Travis

    2009-01-01

    We have developed a finite-difference time-domain (FDTD) fluid-like approach to integrated plasma-and-coupler simulation [1], and show how it can be used to model LH and ICRF couplers in the MST and larger tokamaks.[2] This approach permits very accurate 3-D representation of coupler geometry, and easily includes non-axi-symmetry in vessel wall, magnetic equilibrium, and plasma density. The plasma is integrated with the FDTD Maxwell solver in an implicit solve that steps over electron time-scales, and permits tenuous plasma in the coupler itself, without any need to distinguish or interface between different regions of vacuum and/or plasma. The FDTD algorithm is also generalized to incorporate a time-domain sheath potential [3] on metal structures within the simulation, to look for situations where the sheath potential might generate local sputtering opportunities. Benchmarking of the time-domain sheath algorithm has been reported in the references. Finally, the time-domain software [4] permits the use of particles, either as field diagnostic (test particles) or to self-consistently compute plasma current from the applied RF power.

  14. Study of a superconducting spoke-type cavity and of its associated power coupler; Etude d'une cavite acceleratrice supraconductrice de type spoke et de son coupleur de puissance associe

    Energy Technology Data Exchange (ETDEWEB)

    Mielot, Ch

    2004-12-01

    This work deals with the study of a spoke-type cavity and its associated power coupler. The results of this study are used in the framework of the high power proton linear accelerator of the experimental accelerator-driven system project (XADS). The cavity (F=352 MHz, {beta}=0.35) was tested at 4 K and 2 K. The results at 4 K gave good margins toward XADS requirements that increase the reliability of a spoke based driver. At 2 K the accelerating field reached is the highest in the world for spoke cavities: 16 MV/M. The position and diameter of the coupling have been optimized in order to decrease the HF losses and avoid multi-factor risk. In order to decrease HF losses (taking into account the 20 kW power fed into the cavity) the electric coupling mode has been chosen. Different types of ceramic windows have been studied in order to make this critical point of the coupler reliable: coaxial disk with or without chokes or empty coaxial cylinder. The optimization process focused on the reflected power, the losses in the ceramic and the surface electric field. The risk with chokes has been modeled and studied with the propagation lines theory. A systematic study of the different windows has been done regarding the geometrical parameters. The disk without chokes seems to be a good solution for our application. The power source will be a solid state amplifier (for reliability and modularity reasons). An all over coaxial coupler can be designed and will be fabricated and tested soon. (author)

  15. rf coaxial couplers for high-intensity linear accelerators

    International Nuclear Information System (INIS)

    Manca, J.J.; Knapp, E.A.

    1980-02-01

    Two rf coaxial couplers that are particularly suitable for intertank connection of the disk-and-washer accelerating structure for use in high-intensity linear accelerators have been developed. These devices have very high coupling to the accelerating structure and very low rf power loss at the operating frequency, and they can be designed for any relative particle velocity β > 0.4. Focusing and monitoring devices can be located inside these couplers

  16. A Third Generation Lower Hybrid Coupler

    International Nuclear Information System (INIS)

    Bernabei, S.; Hosea, J.; Kung, C.; Loesser, D.; Rushinski, J.; Wilson, J.R.; Parker, R.

    2001-01-01

    The Princeton Plasma Physics Laboratory (PPPL) and the Massachusetts Institute of Technology (MIT) are preparing an experiment of current profile control using lower-hybrid waves in order to produce and sustain advanced tokamak regimes in steady-state conditions in Alcator C-Mod. Unlike JET's, ToreSupra's and JT60's couplers, the C-Mod lower-hybrid coupler does not employ the now conventional multijunction design, but will have similar characteristics, compactness, and internal power division while retaining full control of the antenna element phasing. This is achieved by using 3 dB vertical power splitters and a stack of laminated plates with the waveguides milled in them. Construction is simplified and allows easy control and maintenance of all parts. Many precautions are taken to avoid arcing. Special care is also taken to avoid the recycling of reflected power which could affect the coupling and the launched n(subscript ||) spectrum. The results from C-Mod should allow further simplification in the designs of the coupler planned for KSTAR (Korea Superconducting Tokamak Advanced Research) and ITER (International Thermonuclear Experimental Reactor)

  17. Waveguide silicon nitride grating coupler

    Science.gov (United States)

    Litvik, Jan; Dolnak, Ivan; Dado, Milan

    2016-12-01

    Grating couplers are one of the most used elements for coupling of light between optical fibers and photonic integrated components. Silicon-on-insulator platform provides strong confinement of light and allows high integration. In this work, using simulations we have designed a broadband silicon nitride surface grating coupler. The Fourier-eigenmode expansion and finite difference time domain methods are utilized in design optimization of grating coupler structure. The fully, single etch step grating coupler is based on a standard silicon-on-insulator wafer with 0.55 μm waveguide Si3N4 layer. The optimized structure at 1550 nm wavelength yields a peak coupling efficiency -2.6635 dB (54.16%) with a 1-dB bandwidth up to 80 nm. It is promising way for low-cost fabrication using complementary metal-oxide- semiconductor fabrication process.

  18. Quantitative analysis of coupler tuning

    International Nuclear Information System (INIS)

    Zheng Shuxin; Cui Yupeng; Chen Huaibi; Xiao Liling

    2001-01-01

    The author deduces the equation of coupler frequency deviation Δf and coupling coefficient β instead of only giving the adjusting direction in the process of matching coupler, on the basis of coupling-cavity chain equivalent circuits model. According to this equation, automatic measurement and quantitative display are realized on a measuring system. It contributes to industrialization of traveling-wave accelerators for large container inspection systems

  19. 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.

  20. Cw RFQ development

    International Nuclear Information System (INIS)

    Schriber, S.O.

    1985-01-01

    A review of research and development related to fabricating and operating radio-frequency quadrupole (RFQ) structures at 100% duty cycle [continuous wave (cw)] is presented, with emphasis on work at the Los Alamos National Laboratory, the Chalk River Nuclear Laboratories, and the University of Frankfurt. Activities in other areas that have an impact on operating cw RFQ systems will be highlighted. 27 refs

  1. Adapting TESLA technology for future cw light sources using HoBiCaT

    Science.gov (United States)

    Kugeler, O.; Neumann, A.; Anders, W.; Knobloch, J.

    2010-07-01

    The HoBiCaT facility has been set up and operated at the Helmholtz-Zentrum-Berlin and BESSY since 2005. Its purpose is testing superconducting cavities in cw mode of operation and it was successfully demonstrated that TESLA pulsed technology can be used for cw mode of operation with only minor changes. Issues that were addressed comprise of elevated dynamic thermal losses in the cavity walls, necessary modifications in the cryogenics and the cavity processing, the optimum choice of operational parameters such as cavity temperature or bandwidth, the characterization of higher order modes in the cavity, and the usability of existing tuners and couplers for cw.

  2. HOM Coupler Optimisation for the Superconducting RF Cavities in ESS

    CERN Document Server

    Ainsworth, R; Calaga, R

    2012-01-01

    The European Spallation Source (ESS) will be the world’s most powerful next generation neutron source. It consists of a linear accelerator, target, and instruments for neutron experiments. The linac is designed to accelerate protons to a final energy of 2.5 GeV, with an average design beam power of 5 MW, for collision with a target used to produce a high neutron flux. A section of the linac will contain Superconducting RF (SCRF) cavities designed at 704 MHz. Beam induced HOMs in these cavities may drive the beam unstable and increase the cryogenic load, therefore HOM couplers are installed to provide sufficient damping. Previous studies have shown that these couplers are susceptible to multipacting, a resonant process which can absorb RF power and lead to heating effects. This paper will show how a coupler suffering from multipacting has been redesigned to limit this effect. Optimisation of the RF damping is also discussed.

  3. Advanced Output Coupling for High Power Gyrotrons

    Energy Technology Data Exchange (ETDEWEB)

    Read, Michael [Calabazas Creek Research, Inc., San Mateo, CA (United States); Ives, Robert Lawrence [Calabazas Creek Research, Inc., San Mateo, CA (United States); Marsden, David [Calabazas Creek Research, Inc., San Mateo, CA (United States); Collins, George [Calabazas Creek Research, Inc., San Mateo, CA (United States); Temkin, Richard [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Guss, William [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Lohr, John [General Atomics, La Jolla, CA (United States); Neilson, Jeffrey [Lexam Research, Redwood City, CA (United States); Bui, Thuc [Calabazas Creek Research, Inc., San Mateo, CA (United States)

    2016-11-28

    The Phase II program developed an internal RF coupler that transforms the whispering gallery RF mode produced in gyrotron cavities to an HE11 waveguide mode propagating in corrugated waveguide. This power is extracted from the vacuum using a broadband, chemical vapor deposited (CVD) diamond, Brewster angle window capable of transmitting more than 1.5 MW CW of RF power over a broad range of frequencies. This coupling system eliminates the Mirror Optical Units now required to externally couple Gaussian output power into corrugated waveguide, significantly reducing system cost and increasing efficiency. The program simulated the performance using a broad range of advanced computer codes to optimize the design. Both a direct coupler and Brewster angle window were built and tested at low and high power. Test results confirmed the performance of both devices and demonstrated they are capable of achieving the required performance for scientific, defense, industrial, and medical applications.

  4. An analysis of multislot directional coupler

    International Nuclear Information System (INIS)

    Arai, Hiroyuki; Goto, Naohisa; Yamamoto, Takumi.

    1986-03-01

    This paper presents an analysis of multislot directional coupler for monitoring the gyrotron output. We solved the boundary value problem of the directional coupler to investigate the detailed effect of finite thickness slot and mutual coupling between slots. Numerical data of coupler design is presented for non-resonant a pair slot, and mode sensitivity in overmoded waveguide is also evaluated. (author)

  5. Coupler for nuclear reactor absorber rods

    International Nuclear Information System (INIS)

    Kerz, K.

    1984-01-01

    A coupler is described for absorber rods being suspended during operation of nuclear reactors which includes plurality of actuating elements being movable for individually and jointly releasing the coupler, the movement of each of the actuating elements for releasing the coupler being independently controllable

  6. All-solid-state cw frequency-doubling Nd:YLiF4/LBO blue laser with 4.33 W output power at 454 nm under in-band diode pumping at 880 nm.

    Science.gov (United States)

    Lü, Yanfei; Zhang, Xihe; Cheng, Weibo; Xia, Jing

    2010-07-20

    We generated efficient blue laser output at 454 nm by intracavity frequency doubling of a continuous-wave (cw) diode-pumped Nd:YLiF(4) (Nd:YLF) laser at 908 nm based on the (4)F(3/2)-(4)I(9/2) transition. With 32.8 W of incident pump power at 880 nm and the frequency-doubling crystal LiB(3)O(5), a level as high as 4.33 W of cw output power at 454 nm is achieved, corresponding to an optical conversion efficiency of 13.2% with respect to the incident pump power. To the best of our knowledge, this is the first blue laser at 454 nm generated by intracavity frequency doubling of a diode-pumped Nd:YLF.

  7. Temporal characterization of plasma cw high-power CO2 laser-matter interaction: contribution to the welding process control

    Science.gov (United States)

    Engel, Thierry; Kane, M.; Fontaine, Joel

    1997-08-01

    During high-power laser welding, gas ionization occurs above the sample. The resulting plasma ignition threshold is related to ionization potential of metallic vapors from the sample, and shielding gases used in the process. In this work, we have characterized the temporal behavior of the radiation emitted by the plasma during laser welding in order to relate the observed signals to the process parameters.

  8. Production of high-power CW UV by resonant frequency quadrupling of a Nd:YLF laser

    International Nuclear Information System (INIS)

    Kuczewski, A.J.; Thorn, C.E.

    1999-01-01

    The authors have constructed a single ring to resonantly double an 18 watt Nd:YLF mode-locked laser and re-double the stored green to produce over 4 watts of power in the ultra-violet (UV). This laser is used to produce a beam of 470 MeV gamma-rays by Compton backscattering the laser beam from 2.8 GeV electrons stored in a synchrotron. Achieving high luminosity of the colliding beams requires very good mode quality and beam stability at the intersection point 22 meters from the laser. The ring consists of six mirrors, with two 25 cm radius of curvature mirrors enclosing each nonlinear crystal. The drive laser is a lamp-pumped Nd:YLF with a 50 ps bunch length at 76 MHz. A pointing stabilizer servo has been constructed as part of the infrared (IR) mode matching telescope. The IR to green conversion is accomplished in a 15 mm long non-critically phased matched LBO crystal located at a 40 micron waist, with an IR conversion efficiency of 70%. A stable, nearly diffraction limited UV beam of up to 4.2 watts is generated in a BBO crystal in the green storage ring. The output power is relatively independent of the efficiency of the LBO and BBO crystals. This fact makes it possible to reduce the amount of non-TEM 00 modes created by walk-off of the UV by using relatively thin BBO crystals. At present, however, the lower bound on the BBO thickness is limited by the loss of conversion efficiency at high power

  9. A modified lower hybrid coupler for TPX

    International Nuclear Information System (INIS)

    Bernabei, S.; Greenough, N.

    1995-01-01

    Efforts have concentrated on redesigning the configuration of the Lower Hybrid coupler for TPX tokamak. Several concerns motivated this redesign: reduce the effect of thermal incompatibility between coupler and rf-window material, reduce weight, reduce the risk of wind failure and address the problem of replaceability, increase the reliability by reducing the number connections and finally, reduce the total cost. The result is a highly compact, light and easily serviceable coupler which incorporates some of the simplicity of the multifunction coupler but preserves the spectral flexibility of a conventional coupler

  10. Generation of 14  W at 589  nm by frequency doubling of high-power CW linearly polarized Raman fiber laser radiation in MgO:sPPLT crystal.

    Science.gov (United States)

    Surin, A A; Borisenko, T E; Larin, S V

    2016-06-01

    We introduce an efficient, single-mode, linearly polarized continuous wave (CW) Raman fiber laser (RFL), operating at 1178 nm, with 65 W maximum output power and a narrow linewidth of 0.1 nm. Single-pass second-harmonic generation was demonstrated using a 20 mm long MgO-doped stoichiometric periodically polled lithium tantalate (MgO:sPPLT) crystal pumped by RFL radiation. Output power of 14 W at 589 nm with 22% conversion efficiency was achieved. The possibility of further power scaling is considered, as no crystal degradation was observed at these power levels.

  11. Spin-Label CW Microwave Power Saturation and Rapid Passage with Triangular Non-Adiabatic Rapid Sweep (NARS) and Adiabatic Rapid Passage (ARP) EPR Spectroscopy

    Science.gov (United States)

    Kittell, Aaron W.; Hyde, James S.

    2015-01-01

    Non-adiabatic rapid passage (NARS) electron paramagnetic resonance (EPR) spectroscopy was introduced by Kittell, A.W., Camenisch, T.G., Ratke, J.J. Sidabras, J.W., Hyde, J.S., 2011 as a general purpose technique to collect the pure absorption response. The technique has been used to improve sensitivity relative to sinusoidal magnetic field modulation, increase the range of inter-spin distances that can be measured under near physiological conditions, and enhance spectral resolution in copper (II) spectra. In the present work, the method is extended to CW microwave power saturation of spin-labeled T4 Lysozyme (T4L). As in the cited papers, rapid triangular sweep of the polarizing magnetic field was superimposed on slow sweep across the spectrum. Adiabatic rapid passage (ARP) effects were encountered in samples undergoing very slow rotational diffusion as the triangular magnetic field sweep rate was increased. The paper reports results of variation of experimental parameters at the interface of adiabatic and non-adiabatic rapid sweep conditions. Comparison of the forward (up) and reverse (down) triangular sweeps is shown to be a good indicator of the presence of rapid passage effects. Spectral turning points can be distinguished from spectral regions between turning points in two ways: differential microwave power saturation and differential passage effects. Oxygen accessibility data are shown under NARS conditions that appear similar to conventional field modulation data. However, the sensitivity is much higher, permitting, in principle, experiments at substantially lower protein concentrations. Spectral displays were obtained that appear sensitive to rotational diffusion in the range of rotational correlation times of 10−3 to 10−7 s in a manner that is analogous to saturation transfer spectroscopy. PMID:25917132

  12. Detuning related coupler kick variation of a superconducting nine-cell 1.3 GHz cavity

    Science.gov (United States)

    Hellert, Thorsten; Dohlus, Martin

    2018-04-01

    Superconducting TESLA-type cavities are widely used to accelerate electrons in long bunch trains, such as in high repetition rate free electron lasers. The TESLA cavity is equipped with two higher order mode couplers and a fundamental power coupler (FPC), which break the axial symmetry of the cavity. The passing electrons therefore experience axially asymmetrical coupler kicks, which depend on the transverse beam position at the couplers and the rf phase. The resulting emittance dilution has been studied in detail in the literature. However, the kick induced by the FPC depends explicitly on the ratio of the forward to the backward traveling waves at the coupler, which has received little attention. The intention of this paper is to present the concept of discrete coupler kicks with a novel approach of separating the field disturbances related to the standing wave and a reflection dependent part. Particular attention is directed to the role of the penetration depth of the FPC antenna, which determines the loaded quality factor of the cavity. The developed beam transport model is compared to dedicated experiments at FLASH and European XFEL. Both the observed transverse coupling and detuning related coupler kick variations are in good agreement with the model. Finally, the expected trajectory variations due to coupler kick variations at European XFEL are investigated and results of numerical studies are presented.

  13. Resonant High Power Combiners

    CERN Document Server

    Langlois, Michel; Peillex-Delphe, Guy

    2005-01-01

    Particle accelerators need radio frequency sources. Above 300 MHz, the amplifiers mostly used high power klystrons developed for this sole purpose. As for military equipment, users are drawn to buy "off the shelf" components rather than dedicated devices. IOTs have replaced most klystrons in TV transmitters and find their way in particle accelerators. They are less bulky, easier to replace, more efficient at reduced power. They are also far less powerful. What is the benefit of very compact sources if huge 3 dB couplers are needed to combine the power? To alleviate this drawback, we investigated a resonant combiner, operating in TM010 mode, able to combine 3 to 5 IOTs. Our IOTs being able to deliver 80 kW C.W. apiece, combined power would reach 400 kW minus the minor insertion loss. Values for matching and insertion loss are given. The behavior of the system in case of IOT failure is analyzed.

  14. 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.

  15. Ultrasound induced by CW laser cavitation bubbles

    International Nuclear Information System (INIS)

    Korneev, N; Montero, P Rodriguez; Ramos-Garcia, R; Ramirez-San-Juan, J C; Padilla-Martinez, J P

    2011-01-01

    The generation of ultrasound by a collapsing single cavitation bubble in a strongly absorbing liquid illuminated with a moderate power CW laser is described. The ultrasound shock wave is detected with hydrophone and interferometric device. To obtain a stronger pulse it is necessary to adjust a liquid absorption and a beam diameter. Their influence can be qualitatively understood with a simple model.

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

    DEFF Research Database (Denmark)

    Leick, Lasse

    2002-01-01

    is not an adequate description of the waveguides. A simple application for an optical couplers is as a 980/1550 nm mulitmplexer for erbium doped wavguide amplifiers. A numerical analysis shows that a directional coupler has acceptable specifications, whereas a mulit mode interference coupler does not. The wavelength......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...... to construct wavelength flattened and process tolerant couplers. A thorough comparison between directional couplers, multi mode interference couplers and interferometer-based couplers has been performed. Numerically all these architectures have the ability to obtain similar wavelength-flatness, but the multi...

  17. Wavelength switchable high-power diode-side-pumped rod Tm:YAG Laser around 2µm.

    Science.gov (United States)

    Wang, Caili; Du, Shifeng; Niu, Yanxiong; Wang, Zhichao; Zhang, Chao; Bian, Qi; Guo, Chuan; Xu, Jialin; Bo, Yong; Peng, Qinjun; Cui, Dafu; Zhang, Jingyuan; Lei, Wenqiang; Xu, Zuyan

    2013-03-25

    We report a high-power diode-side-pumped rod Tm:YAG laser operated at either 2.07 or 2.02 µm depending on the transmission of pumped output coupler. The laser yields 115W of continuous-wave output power at 2.07 µm with 5% output coupling, which is the highest output power for all solid-state 2.07 μm cw rod Tm:YAG laser reported so far. With an output coupler of 10% transmission, the center wavelength of the laser is switched to 2.02 μm with an output power of 77.1 W. This is the first observation of high-power wavelength switchable diode-side-pumped rod Tm:YAG laser around 2 µm.

  18. NBS-LASL cw microtron

    International Nuclear Information System (INIS)

    Penner, S.; Cutler, R.I.; Debenham, D.H.

    1980-01-01

    The NBS-LASL racetrack microtron (RIM) is a joint research project of the National Bureau of Standards and the Los Alamos Scientific Laboratory. The project goals are to determine the feasibility of, and develop the necessary technology for building high-energy, high-current, continuous-beam (cw) electron accelerators using beam recirculation and room-temperature rf accelerating structures. To achieve these goals, a demonstration accelerator will be designed, constructed, and tested. Parameters of the demonstration RIM are: injection energy - 5 MEV; energy gain per pass -12 MeV; number of passes - 15; final beam energy - 185 MeV; maximum current 550 μA. One 450 kW cw klystron operating at 2380 MHz will supply rf power to both the injector linac and the main accelerating section of the RTM. The disk and washer standing wave rf structure being developed at LASL will be used. SUPERFISH calculations indicate that an effective shunt impedance (ZT) of about 100 MΩ/m can be obtained. Thus, rf power dissipation of 25 kW/m results in an energy gain of more than 1.5 MeV/m. Accelerators of this type should be attractive for many applications. At beam energies above about 50 MeV, an RTM should be considerably cheaper to build and operate than a conventional pulsed rf linac of the same maximum energy and time-average beam power. In addition, the RTM provides superior beam quality and a continuous beam which is essential for nuclear physics experiments requiring time-coincidence measurements between emitted particles

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

    International Nuclear Information System (INIS)

    Li, Y. M.; Liu, Kexin; Geng, Rongli

    2014-01-01

    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 0.6A-1.6 MV/m, 21A-34 MV/m, 32A-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 6A-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 MPA'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

  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. Mechanical considerations in cw linacs

    International Nuclear Information System (INIS)

    King, J.D.

    1985-01-01

    An 80-MHz radio-frequency quadrupole (RFQ) linac has been designed, fabricated and operated at 100% duty factor (cw) for the Fusion Materials Irradiation Test (FMIT) project at Los Alamos. This paper describes the design features, fabrication techniques, and operational problems of the device. The RFQ is an assembly of heavy steel, copper-plated weldments. It measures about 15 ft (4.5 m) long by 5 ft (1.5 m) in diameter and weighs over 12 t. Major components are two pair of diametrically orthogonal vanes mounted in a core cylinder. The core is assembled into a manifold cylinder that couples rf power into the vane quadrants. The design features discussed include assembly of hollow wall, flood-cooled components; high-conductivity rf seals; removable and adjustable vanes; and tuning devices. Fabrication challenges such as close-tolerance weldments, vane-tip-contour machining and large-component plating requirements are covered

  2. An RF input coupler system for the CEBAF energy upgrade cryomodule

    International Nuclear Information System (INIS)

    J.R. Delayen; L.R. Doolittle; T. Hiatt; J. Hogan; J. Mammosser; L. Phillips; J. Preble; W.J. Schneider; G. Wu

    1999-01-01

    Long term plans for CEBAF at Jefferson Lab call for achieving 12 GeV in the middle of the next decade and 24 GeV after 2010. Thus an upgraded cryomodule to more than double the present voltage is under development. A new waveguide coupler system has been designed and prototypes are currently being developed. This coupler, unlike the original, has a nominal Q ext of 2.1 x 10 7 , reduced sensitivity of Q ext to mechanical deformation, reduced field asymmetry within the beam envelope, freedom from window arcing with a single window at 300 K, and is capable of transmitting 6kW CW both traveling wave and in full reflection

  3. A Family of L-band SRF Cavities for High Power Proton Driver Applications

    International Nuclear Information System (INIS)

    Rimmer, Robert; Marhauser, Frank

    2009-01-01

    Recent global interest in high duty factor or CW superconducting linacs with high average beam power highlights the need for robust and reliable SRF structures capable of delivering high average RF power to the beam with moderate HOM damping, low interception of halo and good efficiency. Potential applications include proton or H- drivers for spallation neutron sources, neutrino physics, waste transmutation, subcritical reactors, and high-intensity high-energy physics experiments. We describe a family of SRF cavities with a range of Betas capable of transporting beam currents in excess of 10 mA CW with large irises for minimal interception of halo and HOM and power couplers capable of supporting high average power operation. Goals include an efficient cell shape, high packing factor for efficient real-estate gradient and strong HOM damping to ensure stable beam operation,

  4. Miniature mechanical transfer optical coupler

    Science.gov (United States)

    Abel, Philip [Overland Park, KS; Watterson, Carl [Kansas City, MO

    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.

  5. Resonance control for a CW accelerator

    International Nuclear Information System (INIS)

    Young, L.M.; Biddle, R.S.

    1987-01-01

    This paper describes a resonance-control technique that has been successfully applied to several cw accelerating structures built by the Los Alamos National Laboratory for the National Bureau of Standards and for the University of Illinois. The technique involves sensing the rf fields in an accelerating structure as well as the rf power feeding into the cavity and, then, using the measurement to control the resonant frequency of the structure by altering the temperature of the structure. The temperature of the structure is altered by adjusting the temperature of the circulating cooling water. The technique has been applied to continuous wave (cw) side-coupled cavities only but should have applications with most high-average-power accelerator structures. Some additional effort would be required for pulsed systems

  6. 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.

  7. Fabrication of LD-3 Polymer Directional Couplers

    National Research Council Canada - National Science Library

    Chen, Ray T

    1998-01-01

    .... LD-3 polymer directional couplers arc designed and fabricated to operate at 1.3 microns. Waveguide propagation losses, device characterization, demonstration of cross coupling and packaged device pictures are presented in this final report.

  8. UV written compact broadband optical couplers

    DEFF Research Database (Denmark)

    Olivero, Massimo; Svalgaard, Mikael

    2005-01-01

    In this paper the first demonstration of compact asymmetric directional couplers made by UV writing is presented. The combined performance in terms bandwidth, loss and compactness exceeds that reported using other, more elaborate fabrication techniques.......In this paper the first demonstration of compact asymmetric directional couplers made by UV writing is presented. The combined performance in terms bandwidth, loss and compactness exceeds that reported using other, more elaborate fabrication techniques....

  9. 50W CW output power and 12mJ pulses from a quasi-2-level Yb:YAG ceramic rod laser end-pumped at the 969nm zero-phonon line

    Science.gov (United States)

    Fries, Christian; Weitz, Marco; Theobald, Christian; v. Löwis of Menar, Patric; Bartschke, Jürgen; L'huillier, Johannes A.

    2015-02-01

    With the advent of high power and narrow bandwidth 969 nm pump diodes, direct pumping into the upper laser level of Yb:YAG and hence quasi-2-level lasers became possible. Pumping directly into the emitting level leads to higher quantum efficiency and reduction of non-radiative decay. Consequently, thermal load, thermal lensing and risk of fracture are reduced significantly. Moreover pump saturation and thermal population of uninvolved energy-levels in ground and excited states are benefical for a homogenous distribution of the pump beam as well as the reduction of reabsorption loss compared to 3-level systems, which allows for high-power DPSS lasers. Beside continuous-wave (cw) operation, nanosecond pulses with a repetition rate between 1 and 5 kHz are an attractive alternative to flashlamp-pumped systems (10-100 Hz) in various measurement applications that require higher data acquisition rates because of new faster detectors. Based on measurements of the absorption and a detailed numerical model for pump beam distribution, including beam propagation and saturation factors, power-scaling of a ceramic rod Yb:YAG oscillator was possible. Finally a cw output power of 50 W with 33 % pump efficiency at 1030 nm has been demonstrated (M2 dumping of this system. The cavity-dumped setup allowed for 3-10 ns pulses with a pulse energy of 12.5 mJ at 1 kHz (M2 < 1.1). In order to achieve these results a systematic experimental and numerical investigation on gain dynamics and the identification of different stable operating regimes has been carried out.

  10. 3 μm CW lasers for myringotomy and microsurgery.

    Science.gov (United States)

    Linden, Kurt J; Pfeffer, Christian P; Sousa, John Gary; D'Alleva, Nicholas; Aslani, Arash; Gorski, Grzegorz; Kenna, Margaret; Poe, Dennis S

    2013-03-08

    This paper describes the development and implementation of 3 μm lasers for myringotomy and microsurgery. Two different lasers were investigated. The first, an Er-doped, CW zirconate glass fiber laser optically pumped by a 970 nm diode laser, emitted > 1 W of CW power at 2.76 μm with concomitant green incoherent emission that served as a convenient visible illumination beam. The second, a 1 W CW Er:YAG solid-state laser also optically pumped by a 970 nm diode laser, emitted > 1 W of CW power at 2.94 μm, coincident with the strongest infrared water absorption peak. Running CW, both lasers are expected to avoid the loud acoustical shocks associated with pulsed lasers. Myringotomies were carried out with the Er:YAG laser on anaesthetized guinea pigs and the effects of the laser were documented. Laser ablated samples of tympanic membrane, soft tissue and bone were histologically examined. Histology results indicated that the CW Er:YAG laser is a potential candidate for a new myringotomy tool and possibly for otologic microsurgery, but deliverable power levels need to be increased to the 2 W (or higher) level. This work was funded under NIH SBIR Grant No. 5R44DC004899.

  11. High efficiency diffractive grating coupler based on transferred silicon nanomembrane overlay on photonic waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Saha, Tapas Kumar; Zhou Weidong [University of Texas at Arlington, Department of Electrical Engineering, NanoFAB Center, Arlington, TX 76019-0072 (United States)

    2009-04-21

    We report here the design of a new type of high efficiency grating coupler, based on single crystalline Si nanomembrane overlay and stacking. Such high efficiency diffractive grating couplers are designed for the purpose of coupling light between single mode fibres and nanophotonic waveguides, and for the coupling between multiple photonic interconnect layers for compact three-dimensional vertical integration. Two-dimensional model simulation based on eigenmode expansion shows a diffractive power-up efficiency of 81% and a fibre coupling efficiency of 64%. With nanomembrane stacking, it is feasible to integrate the side-distributed Bragg reflector and bottom reflector, which can lead to the diffractive power-up efficiency and the fibre coupling efficiency of 97% and 73.5%, respectively. For a negatively detuned coupler, the bottom reflector is not needed, and the diffractive power-up efficiency can reach 98% over a large spectral range. The device is extremely tolerant to fabrication errors.

  12. Nuclear activated cw chemical laser

    International Nuclear Information System (INIS)

    Roberts, T.G.

    1982-01-01

    A cw chemical laser which uses processed radioactive waste to produce active atoms from a chemically inactive gas before being mixed with another molecule such as hydrogen or deuterium is disclosed. This laser uses no toxic or corrosive fuels and does not require any electrical or other type of auxiliary power supply. The energy released by the radioactive material is used to produce the active atoms such as fluorine. This is accomplished by using the radiation products from processed radioactive waste to dissociate the inert gas in the plenum of the laser. The radioactive material is held in the passageway walls of a device similar to a heat exchanger. The exchanger device may be located in the gas generator section of a chemical laser. The inactive gas is passed through the exchanger device and while passing through it the radiation from the radioactive material dissociates the gas, producing a concentration of free active atoms. This active atom generator then feeds the nozzle bank or mixing section of a laser to produce a lasing action

  13. Stable CW Single Frequency Operation of Fabry-Perot Laser Diodes by Self-Injection Phase Locking

    Science.gov (United States)

    Duerksen, Gary L.; Krainak, Michael A.

    1999-01-01

    Previously, single-frequency semiconductor laser operation using fiber Bragg gratings has been achieved by tWo methods: 1) use of the FBG as the output coupler for an anti-reflection-coated semiconductor gain element'; 2) pulsed operation of a gain-switched Fabry-Perot laser diode with FBG-optical and RF-electrical feedback'. Here, we demonstrate CW single frequency operation from a non-AR coated Fabry-Perot laser diode using only FBG optical feedback.

  14. Zero-dispersion wavelength independent quasi-CW pumped supercontinuum generation

    DEFF Research Database (Denmark)

    Larsen, Casper; Sørensen, Simon Toft; Noordegraaf, Danny

    2013-01-01

    Continuous wave (CW) pumped supercontinuum generation depends strongly on the zero-dispersion wavelength (ZDW) of the fiber due to the low peak power. Here we study several photonic crystal fibers by use of a gain-switched CW pump laser and investigate for what power level the supercontinuum...

  15. A coupler for parasitic mode diagnosis in an X-band triaxial klystron amplifier

    Directory of Open Access Journals (Sweden)

    Wei Zhang

    2017-10-01

    Full Text Available The traditional methods of parasitic mode excitation diagnosis in an X-band triaxial klystron amplifier (TKA meet two difficulties: limited installation space and vacuum sealing. In order to solve these issues, a simple and compact coupler with good sealing performance, which can prevent air flow between the main and the auxiliary waveguides, is proposed and investigated experimentally. The coupler is designed with the aperture diffraction theory and the finite-different time-domain (FDTD method. The designed coupler consists of a main coaxial waveguide (for microwave transmission and a rectangular auxiliary waveguide (for parasitic mode diagnosis. The entire coupler structure has been fabricated by macromolecule polymer which is transparent to microwave signal in frequency range of X-band. The metal coating of about 200 microns has been performed through electroplating technique to ensure that the device operates well at high power. A small aperture is made in the metal coating. Hence, microwave can couple through the hole and the wave-transparent medium, whereas air flow is blocked by the wave-transparent medium. The coupling coefficient is analyzed and simulated with CST software. The coupler model is also included in particle-in-cell (PIC simulation with CHIPIC software and the associated parasitic mode excitation is studied. A frequency component of 11.46 GHz is observed in the FFT of the electric field of the drift tube and its corresponding competition mode appears as TE61 mode according to the electric field distribution. Besides, a frequency component of 10.8 GHz is also observed in the FFT of the electric field. After optimization of TE61 mode suppression, an experiment of the TKA with the designed coupler is carried out and the parasitic mode excitation at 10.8 GHz is observed through the designed coupler.

  16. Acoustic Coupler for the Acquisition of Coronary Artery Murmurs

    DEFF Research Database (Denmark)

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

    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 range from 200-700 Hz. The capability of the sensor to record diastolic heart sound in the relevant frequency range indicates...... and the microphone used was evaluated through a large study, where the coupler was used for recording the murmur sound from 464 heart patients. The power spectrum of the diastolic heart sounds was analyzed to determine the characteristics of the frequency spectrum. The preliminary results show, that it was possible...

  17. 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...

  18. Engineering design of 500KW CW collector

    International Nuclear Information System (INIS)

    Kumar, Ramesh; Mishra, Deepak; Prasad, M.; Hannuarakar, P.R.

    2006-01-01

    An electron beam collector for 500kW beam power has been designed to test the electron gun. The gun is designed for 250kW, 350MHz CW Klystron with 50% efficiency. This will also help in preliminary studies related to final collector design for Klystron. This paper presents the design parameters, thermal analysis and mechanical features of the design. Electron trajectory on inside wall of the collector is determined with EGUN and computational flow dynamics simulation was done on ANSYS for cooling requirements. (author)

  19. Power scaling of laser diode pumped Pr3+:LiYF4 cw lasers: efficient laser operation at 522.6 nm, 545.9 nm, 607.2 nm, and 639.5 nm.

    Science.gov (United States)

    Gün, Teoman; Metz, Philip; Huber, Günter

    2011-03-15

    We report efficient cw laser operation of laser diode pumped Pr(3+)-doped LiYF4 crystals in the visible spectral region. Using two InGaN laser diodes emitting at λ(P)=443.9 nm with maximum output power of 1 W each and a 2.9-mm-long crystal with a doping concentration of 0.5%, output powers of 938 mW, 418 mW, 384 mW, and 773 mW were achieved for the laser wavelengths 639.5 nm, 607.2 nm, 545.9 nm, and 522.6 nm, respectively. The maximum absorbed pump powers were approximately 1.5 W, resulting in slope efficiencies of 63.6%, 32.0%, 52.1%, and 61.5%, as well as electro-optical efficiencies of 9.4%, 4.2%, 3.8%, and 7.7%, respectively. Within these experiments, laser diode-pumped laser action at 545.9 nm was demonstrated for what is believed to be the first time.

  20. Broadband Silicon-On-Insulator directional couplers using a combination of straight and curved waveguide sections.

    Science.gov (United States)

    Chen, George F R; Ong, Jun Rong; Ang, Thomas Y L; Lim, Soon Thor; Png, Ching Eng; Tan, Dawn T H

    2017-08-03

    Broadband Silicon-On-Insulator (SOI) directional couplers are designed based on a combination of curved and straight coupled waveguide sections. A design methodology based on the transfer matrix method (TMM) is used to determine the required coupler section lengths, radii, and waveguide cross-sections. A 50/50 power splitter with a measured bandwidth of 88 nm is designed and fabricated, with a device footprint of 20 μm × 3 μm. In addition, a balanced Mach-Zehnder interferometer is fabricated showing an extinction ratio of >16 dB over 100 nm of bandwidth.

  1. 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.

  2. 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.

  3. Multipacting Simulations of Tuner-adjustable waveguide coupler (TaCo) with CST

    CERN Document Server

    Shafqat, Nuaman; Wegner, Rolf

    2015-01-01

    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 PIC solver of CST PS. Simulations are performed for complete field sweeps and results are analysed.

  4. A 2 MW, CW, 170 GHz gyrotron for ITER

    International Nuclear Information System (INIS)

    Piosczyk, B.; Arnold, A.; Alberti, S.

    2003-01-01

    A 140 GHz gyrotron for CW operation is under development for the stellarator W7-X. With a prototype tube a microwave output power of about 0.9 MW has been obtained in pulses up to 180 s, limited by the capability of the high voltage power supply. The development work on coaxial cavity gyrotrons has demonstrated the feasibility of manufacturing of a 2 MW, CW 170 GHz tube that could be used for ITER. The problems specific to the coaxial arrangement have been investigated and all relevant information needed for an industrial realization of a coaxial gyrotron have been obtained in short pulse experiments (up to 17 ms). The suitability of critical components for a 2 MW, CW coaxial gyrotron has been studied and a first integrated design has been done. (author)

  5. CW RFQ fabrication and engineering

    International Nuclear Information System (INIS)

    Schrage, D.; Young, L.; Roybal, P.

    1998-01-01

    The design and fabrication of a four-vane RFQ to deliver a 100 mA CW proton beam at 6.7 MeV is described. This linac is an Oxygen-Free Electrolytic (OFE) copper structure 8 m in length and was fabricated using hydrogen furnace brazing as the joining technology

  6. Design considerations in achieving 1 MW CW operation with a whispering-gallery-mode gyrotron

    International Nuclear Information System (INIS)

    Felch, K.; Feinstein, J.; Hess, C.; Huey, H.; Jongewaard, E.; Jory, H.; Neilson, J.; Pendleton, R.; Pirkle, D.; Zitelli, L.

    1989-09-01

    Varian is developing high-power, CW gyrotrons at frequencies in the range 100 GHz to 150 GHz, for use in electron cyclotron heating applications. Early test vehicles have utilized a TE 15,2,1 interaction cavity, have achieved short-pulse power levels of 820 kW and average power levels of 80 kW at 140 GHz. Present tests are aimed at reaching 400 kW under CW operating conditions and up to 1 MW for short pulse durations. Work is also underway on modifications to the present design that will enable power levels of up to 1 MW CW to be achieved. 7 refs., 2 figs

  7. Studies of calorimeter absorbers for CW and pulsed CO2 lasers

    International Nuclear Information System (INIS)

    Gunn, S.R.

    1975-01-01

    Solid and liquid absorbers, used in calorimeters to measure the power and energy of cw and pulsed CO 2 lasers, have been studied from 9.24 to 10.76 μm (cw) and near 10.588 μm (pulsed). The principal materials used were magnesium oxide, lithium fluoride, polystyrene, polytetrafluorethylene, carbon tetrachloride and kerosene. (U.S.)

  8. 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.

  9. CW SRF systems with ingot niobium and their applications

    International Nuclear Information System (INIS)

    Myneni, Ganapati

    2011-01-01

    Continuous wave (CW) superconducting radio frequency (SRF) accelerator systems are needed not only for discovery science initiatives through out the world but they are also expected to find applications in a wide variety of programs including advanced reactor cycles using thorium as nuclear fuel, commercial and university compact linacs and FEL's. However these state of the art particle accelerator systems are very expensive to build and consume significant power in their operations. In the present world economic, energy sustainability and global warming concerns, we must improve the efficiency of the CW SRF accelerator systems considerably and in a cost effective manner. In this presentation I will review the current status of the CW SRF systems including the recent advances in improving the quality factor of the SRF cavities at very much reduced costs with simplified process procedures. (author)

  10. Measurement of large nonlinear refractive index of natural pigment extracted from Hibiscus rosa-sinensis leaves with a low power CW laser and by spatial self-phase modulation technique

    Science.gov (United States)

    Biswas, S.; Kumbhakar, P.

    2017-02-01

    We have reported here, for the first time, to the best of our knowledge, a high nonlinear refractive index (n2e) of a natural pigment extracted from Hibiscus rosa-sinensis leaves by using spatial self-phase modulation technique (SSPM) with a low power CW He-Ne laser radiation at 632.8 nm. It is found by UV-Vis absorption spectroscopic analysis that chlrophyll-a, chlrophyll-b and carotenoid are present in the pigment extract with 56%, 25% and 19%, respectively. The photoluminescence (PL) emission characteristics of the extracted samples have also been measured at room temperature as well as in the temperature range of 283-333 K to investigate the effect of temperature on luminescent properties of the sample. By analyzing the SSPM experimental data, the nonlinear refractive index value of pigment extract has been determined to be 3.5 × 10- 5 cm2/W. The large nonlinear refractive index has been assigned due to asymmetrical structure, molecular reorientation and thermally induced nonlinearity in the sample. The presented results might open new avenues for the green and economical technique of syntheses of organic dyes with such a large nonlinear optical property.

  11. Structural Analysis of Taper-Threaded Rebar Couplers

    International Nuclear Information System (INIS)

    Chu, Seok Jae; Kwon, Hyuk Mo; Seo, Sang Hwan

    2014-01-01

    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 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

  12. Efficient diode-pumped Tm:KYW 1.9-μm microchip laser with 1 W cw output power.

    Science.gov (United States)

    Gaponenko, Maxim; Kuleshov, Nikolay; Südmeyer, Thomas

    2014-05-19

    We report on a diode-pumped Tm:KYW microchip laser generating 1 W continuous-wave output power. The laser operates at a wavelength of 1.94 μm in the fundamental TEM(00) mode with 71% slope efficiency relative to the absorbed pump radiation and 59% slope efficiency relative to the incident pump radiation. The optical-to-optical laser efficiency is 43%.

  13. Efficient diode-pumped Tm:KYW 1.9-μm microchip laser with 1 W cw output power

    OpenAIRE

    Gaponenko, M. S.; Kuleshov, N. V.; Südmeyer, T.

    2014-01-01

    We report on a diode-pumped Tm:KYW microchip laser generating 1 W continuous-wave output power. The laser operates at a wavelength of 1.94 μm in the fundamental TEM00 mode with 71% slope efficiency relative to the absorbed pump radiation and 59% slope efficiency relative to the incident pump radiation. The optical-to-optical laser efficiency is 43%.

  14. Free electron laser with small period wiggler and sheet electron beam: A study of the feasibility of operation at 300 GHz with 1 MW CW output power

    International Nuclear Information System (INIS)

    Booske, J.H.; Granatstein, V.L.; Antonsen, T.M. Jr.

    1988-01-01

    The use of a small period wiggler (/ell//sub ω/ 2 ). Based on these encouraging results, a proof-of-principle experiment is being assembled, and is aimed at demonstrating FEL operating at 120 GHz with 300 kW output power in 1 μs pulses: electron energy would be 410 keV. Preliminary design of a 300 GHz 1 MW FEL with an untapered wiggler is also presented. 10 refs., 5 figs., 3 tabs

  15. Mode conversion in hybrid optical fiber coupler

    Science.gov (United States)

    Stasiewicz, Karol A.; Marc, P.; Jaroszewicz, Leszek R.

    2012-04-01

    Designing of all in-line fiber optic systems with a supercontinuum light source gives some issues. The use of a standard single mode fiber (SMF) as an input do not secure single mode transmission in full wavelength range. In the paper, the experimental results of the tested hybrid fiber optic coupler were presented. It was manufactured by fusing a standard single mode fiber (SMF28) and a photonic crystal fiber (PCF). The fabrication process is based on the standard fused biconical taper technique. Two types of large mode area fibers (LMA8 and LAM10 NKT Photonics) with different air holes arrangements were used as the photonic crystal fiber. Spectral characteristics within the range of 800 nm - 1700 nm were presented. All process was optimized to obtain a mode conversion between SMF and PCF and to reach a single mode transmission in the PCF output of the coupler.

  16. All silicon waveguide spherical microcavity coupler device.

    Science.gov (United States)

    Xifré-Pérez, E; Domenech, J D; Fenollosa, R; Muñoz, P; Capmany, J; Meseguer, F

    2011-02-14

    A coupler based on silicon spherical microcavities coupled to silicon waveguides for telecom wavelengths is presented. The light scattered by the microcavity is detected and analyzed as a function of the wavelength. The transmittance signal through the waveguide is strongly attenuated (up to 25 dB) at wavelengths corresponding to the Mie resonances of the microcavity. The coupling between the microcavity and the waveguide is experimentally demonstrated and theoretically modeled with the help of FDTD calculations.

  17. Passive radio frequency peak power multiplier

    Science.gov (United States)

    Farkas, Zoltan D.; Wilson, Perry B.

    1977-01-01

    Peak power multiplication of a radio frequency source by simultaneous charging of two high-Q resonant microwave cavities by applying the source output through a directional coupler to the cavities and then reversing the phase of the source power to the coupler, thereby permitting the power in the cavities to simultaneously discharge through the coupler to the load in combination with power from the source to apply a peak power to the load that is a multiplication of the source peak power.

  18. CAMAC/PDP 11-45 coupler

    International Nuclear Information System (INIS)

    Pascual, Joseph; Raoul, J.-C.

    1978-04-01

    The complex experimental devices used in high energy physics require the use of minicomputers. The latter are coupled to the detectors using the CAMAC standard which has been adopted by the majority of high energy physics laboratories, much to the ease of international collaboration. The performance of industrially available interfaces having shown to be inadequate, the DPhPE has undertaken the development of a multibranche CAMAC/PDP 11-45 coupler. This system can control up to 49 crates shared out between 7 branches. It consists of a programmed channel and up to three high speed (556 Kwords/second) automatic channels. The four channels can work simultaneously through time sharing. The coupler includes a LAM handling system. The correspondent software has been developed simultaneously: the monitor is an extended version of the RT 11 system supplied by the manufacturer. This interface has been used so far in five experiments on the CERN PS and SPS. Besides this publication, intended to give a description of the coupler, a user's utilisation manuel exists in English [fr

  19. Novel, compact, and simple ND:YVO4 laser with 12 W of CW optical output power and good beam quality

    Science.gov (United States)

    Zimer, H.; Langer, B.; Wittrock, U.; Heine, F.; Hildebrandt, U.; Seel, S.; Lange, R.

    2017-11-01

    We present first, promising experiments with a novel, compact and simple Nd:YVO4 slab laser with 12 W of 1.06 μm optical output power and a beam quality factor M2 2.5. The laser is made of a diffusion-bonded YVO4/Nd:YVO4 composite crystal that exhibits two unique features. First, it ensures a one-dimensional heat removal from the laser crystal, which leads to a temperature profile without detrimental influence on the laser beam. Thus, the induced thermo-optical aberrations to the laser field are low, allowing power scaling with good beam quality. Second, the composite crystal itself acts as a waveguide for the 809 nm pump-light that is supplied from a diode laser bar. Pump-light shaping optics, e.g. fast- or slow-axis collimators can be omitted, reducing the complexity of the system. Pump-light redundancy can be easily achieved. Eventually, the investigated slab laser might be suitable for distortion-free high gain amplification of weak optical signals.

  20. Development of higher order mode couplers at Cornell

    International Nuclear Information System (INIS)

    Amato, J.C.

    1988-01-01

    Higher order mode (HOM) couplers are integral parts of a superconducting accelerator cavity. The damping which the couplers must provide is dictated by the frequency and shunt impedance of the cavity modes as well as by the stability requirements of the accelerator incorporating the cavities. Cornell's 5-cell 1500 MHz elliptical cavity was designed for use in a 50 x 50 GeV electron-positron storage ring with a total beam current of 3.5 mA (CESR-II). HOM couplers for the Cornell cavity were designed and evaluated with this machine in mind. The development of these couplers is described in this paper. 8 references, 8 figures

  1. Novel beam delivery fibers for delivering flat-top beams with controlled BPP for high power CW and pulsed laser applications

    Science.gov (United States)

    Jollivet, C.; Farley, K.; Conroy, M.; Abramczyk, J.; Belke, S.; Becker, F.; Tankala, K.

    2016-03-01

    Single-mode (SM) kW-class fiber lasers are the tools of choice for material processing applications such as sheet metal cutting and welding. However, application requirements include a flat-top intensity profile and specific beam parameter product (BPP). Here, Nufern introduces a novel specialty fiber technology capable of converting a SM laser beam into a flat-top beam suited for these applications. The performances are demonstrated using a specialty fiber with 100 μm pure silica core, 0.22 NA surrounded by a 120 μm fluorine-doped layer and a 360 μm pure silica cladding, which was designed to match the conventional beam delivery fibers. A SM fiber laser operating at a wavelength of 1.07 μm and terminated with a large-mode area (LMA) fiber with 20 μm core and 0.06 NA was directly coupled in the core of the flat-top specialty fiber using conventional splicing technique. The output beam profile and BPP were characterized first with a low-power source and confirmed using a 2 kW laser and we report a beam transformation from a SM beam into a flat-top intensity profile beam with a 3.8 mm*mrad BPP. This is, to the best of our knowledge, the first successful beam transformation from SM to MM flat-top with controlled BPP in a single fiber integrated in a multi-kW all-fiber system architecture.

  2. Efficient room temperature cw Yb:glass laser pumped by a 946nm Nd:YAG laser

    OpenAIRE

    Koch, R.; Clarkson, W.A.; Hanna, D.C.; Jiang, S.; Myers, M.J.; Rhonehouse, D.; Hamlin, S.J.; Griebner, U.; Schönnagel, H.

    1997-01-01

    By pumping with a cw diode-pumped Nd:YAG laser operating at 946nm laser operation of a new Yb-doped phosphate glass with 440mW cw output power and a slope efficiency of 48% with respect to the absorbed pump power was achieved at room temperature

  3. Multipacting in a coaxial coupler with bias voltage for SRF operation with a large beam current

    Science.gov (United States)

    Liu, Z.-K.; Wang, Ch.; Chang, F.-Y.; Chang, L.-H.; Chang, M.-H.; Chen, L.-J.; Chung, F.-T.; Lin, M.-C.; Lo, C.-H.; Tsai, C.-L.; Tsai, M.-H.; Yeh, M.-S.; Yu, T.-C.

    2016-09-01

    A superconducting radio-frequency (SRF) module is commonly used for a high-energy accelerator; its purpose is to provide energy to the particle beam. Because of the low power dissipation and smaller impedance of a higher-order mode for this module, it can provide more power to the particle beam with better stability through decreasing the couple bunch instability. A RF coupler is necessary to transfer the high power from a RF generator to the cavity. A coupler of coaxial type is a common choice. With high-power operation, it might suffer from multipacting, which is a resonance phenomenon due to re-emission of secondary electrons. Applying a bias voltage between inner and outer conductors of the coaxial coupler might increase or decrease the strength of the multipacting effect. We studied the effect of a bias voltage on multipacting using numerical simulation to track the motion of the electrons. The simulation results and an application for SRF operation with a large beam current are presented in this paper.

  4. Compact broadband polarization beam splitter using a symmetric directional coupler with sinusoidal bends.

    Science.gov (United States)

    Zhang, Fan; Yun, Han; Wang, Yun; Lu, Zeqin; Chrostowski, Lukas; Jaeger, Nicolas A F

    2017-01-15

    We design and demonstrate a compact broadband polarization beam splitter (PBS) using a symmetric directional coupler with sinusoidal bends on a silicon-on-insulator platform. The sinusoidal bends in our PBS suppress the power exchange between two parallel symmetric strip waveguides for the transverse-electric (TE) mode, while allowing for the maximum power transfer to the adjacent waveguide for the transverse-magnetic (TM) mode. Our PBS has a nominal coupler length of 8.55 μm, and it has an average extinction ratio (ER) of 12.0 dB for the TE mode, an average ER of 20.1 dB for the TM mode, an average polarization isolation (PI) of 20.6 dB for the through port, and an average PI of 11.5 dB for the cross port, all over a bandwidth of 100 nm.

  5. 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...

  6. A novel bridge coupler for SSC coupled cavity linac

    International Nuclear Information System (INIS)

    Yao, C.G.; Chang, C.R.; Funk, W.

    1992-01-01

    A novel magnetically coupled multi-cavity bridge coupler is proposed for SSC Coupled-Cavity-Linac (CCL). The bridge coupler is a five cell disc-loaded waveguide with a small central aperture used for measurement and two large curved coupling slots near the edge on each disc. The two coupling slots on the adjacent disc are rotated 90 degrees in orientation to reduce the direct coupling. This type of structure is capable of producing very large coupling (>10% in our longest bridge coupler). Also because of the small opening on the discs, the high-order-modes are very far (> 300 MHz) above the operating mode. Thus for long bridge couplers, the magnetic coupled structure should provide maximum coupling with minimum mode mixing problems. In this paper both physics and engineering issues of this new bridge coupler are presented. (Author) 5 refs., 2 tabs., 6 figs

  7. Apodized grating coupler using fully-etched nanostructures

    International Nuclear Information System (INIS)

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

    2016-01-01

    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. (paper)

  8. Study on the coaxial couplers for disk and washer loaded accelerating structures

    International Nuclear Information System (INIS)

    Dajkovskij, A.G.; Paramonov, V.V.; Portugalov, Yu.I.; Ryabov, A.D.; Ryabova, T.D.

    1983-01-01

    The paper describes the dispersion and energy properties of the coaxial coupler (CC), which is a promising component for an accelerating system, with the disk and washer (DAW) structure. Resonators, consisting of the DAW structure sections and CC are shown to persist the main advantage of DAW structure, i.e. high stability of the accelerating field distribution. Therewith RF power losses are small. The presence of nonsymetriric modes in the neighbourbood of the operating mode is noted

  9. 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.

  10. Fiber-optic couplers as displacement sensors

    Science.gov (United States)

    Baruch, Martin C.; Gerdt, David W.; Adkins, Charles M.

    2003-04-01

    We introduce the novel concept of using a fiber-optic coupler as a versatile displacement sensor. Comparatively long fiber-optic couplers, with a coupling region of approximately 10 mm, are manufactured using standard communication SM fiber and placed in a looped-back configuration. The result is a displacement sensor, which is robust and highly sensitive over a wide dynamic range. This displacement sensor resolves 1-2 μm over distances of 1-1.5 mm and is characterized by the essential absence of a 'spring constant' plaguing other strain gauge-type sensors. Consequently, it is possible to couple to extremely weak vibrations, such as the skin displacement affected by arterial heart beat pulsations. Used as a wrist-worn heartbeat monitor, the fidelity of the arterial pulse signal has been shown to be so high that it is possible to not only determine heartbeat and breathing rates, but to implement a new single-point blood pressure measurement scheme which does not squeeze the arm. In an application as a floor vibration sensor for the non-intrusive monitoring of independently living elderly, the sensor has been shown to resolve the distinct vibration spectra of different persons and different events.

  11. 100 GHz, 1 MW, CW gyrotron study program. Final report

    International Nuclear Information System (INIS)

    Felch, K.; Bier, R.; Caplan, M.; Jory, H.

    1983-09-01

    The results of a study program to investigate the feasibility of various approaches in designing a 100 GHz, 1 MW CW gyrotron are presented. A summary is given of the possible configurations for a high average power, high frequency gyrotron, including an historical survey of experimental results which are relevant to the various approaches. A set of basic scaling considerations which enable qualitative comparisons between particular gyrotron interaction circuits is presented. These calculations are important in understanding the role of various electron beam and circuit parameters in achieving a viable gyrotron design. Following these scaling exercises, a series of design calculations is presented for a possible approach in achieving 100 GHz, 1 MW CW. These calculations include analyses of the electron gun and interaction circuit parts of the gyrotron, and a general analysis of other aspects of a high average power, high frequency gyrotron. Scalability of important aspects of the design to other frequencies is also discussed, as well as key technology issues

  12. Resonance control for a cw [continuous wave] accelerator

    International Nuclear Information System (INIS)

    Young, L.M.; Biddle, R.S.

    1987-01-01

    A resonance-control technique is described that has been successfully applied to several cw accelerating structures built by the Los Alamos National Laboratory for the National Bureau of Standards and for the University of Illinois. The technique involves sensing the rf fields in an accelerating structure as well as the rf power feeding into the cavity and, then, using the measurement to control the resonant frequency of the structure by altering the temperature of the structure. The temperature of the structure is altered by adjusting the temperature of the circulating cooling water. The technique has been applied to continuous wave (cw) side-coupled cavities only but should have applications with most high-average-power accelerator structures. Some additional effort would be required for pulsed systems

  13. Balanced PIN-TIA photoreceiver with integrated 3 dB fiber coupler for distributed fiber optic sensors

    Science.gov (United States)

    Datta, Shubhashish; Rajagopalan, Sruti; Lemke, Shaun; Joshi, Abhay

    2014-06-01

    We report a balanced PIN-TIA photoreceiver integrated with a 3 dB fiber coupler for distributed fiber optic sensors. This detector demonstrates -3 dB bandwidth >15 GHz and coupled conversion gain >65 V/W per photodiode through either input port of the 3 dB coupler, and can be operated at local oscillator power of +17 dBm. The combined common mode rejection of the balanced photoreceiver and the integrated 3 dB coupler is >20 dB. We also present measurement results with various optical stimuli, namely impulses, sinusoids, and pseudo-random sequences, which are relevant for time domain reflectometry, frequency domain reflectometry, and code correlation sensors, respectively.

  14. 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.

  15. Compression, splitting and switching of bright and dark solitons in nonlinear directional coupler

    International Nuclear Information System (INIS)

    Mandal, Basanti; Chowdhury, A. Roy

    2006-01-01

    A detailed numerical simulation of the switching, compression and splitting characteristics of various solitary pulses (bright, grey and dark) are carried out by a direct solution of the associated coupled NLS equation. Important physical parameters of the out going pulse such as, intensity distribution, root mean square spatial and temporal width and chirp are calculated. Both the cases of symmetric and asymmetric couplers are considered. The important phenomenon of periodic power transfer from one channel to the other unfolds. The compression varies with the type of pulse launched in the initial channel. It is observed that the chirping of the initial pulse has an optimum value and it vary quite noticeably with the character of the pulse and couplers, symmetric and asymmetric

  16. Investigations and Simulations of All optical Switches in linear state Based on Photonic Crystal Directional Coupler

    Directory of Open Access Journals (Sweden)

    S. Maktoobi

    2014-10-01

    Full Text Available Switching is a principle process in digital computers and signal processing systems. The growth of optical signal processing systems, draws particular attention to design of ultra-fast optical switches. In this paper, All Optical Switches in linear state Based On photonic crystal Directional coupler is analyzed and simulated. Among different methods, the finite difference time domain method (FDTD is a preferable method and is used. We have studied the application of photonic crystal lattices, the physics of optical switching and photonic crystal Directional coupler. In this paper, Electric field intensity and the power output that are two factors to improve the switching performance and the device efficiency are investigated and simulated. All simulations are performed by COMSOL software.

  17. A reliable cw Lyman-α laser source for future cooling of antihydrogen

    International Nuclear Information System (INIS)

    Kolbe, Daniel; Beczkowiak, Anna; Diehl, Thomas; Koglbauer, Andreas; Sattler, Matthias; Stappel, Matthias; Steinborn, Ruth; Walz, Jochen

    2012-01-01

    We demonstrate a reliable continuous-wave (cw) laser source at the 1 S–2 P transition in (anti)hydrogen at 121.56 nm (Lyman-α) based on four-wave sum-frequency mixing in mercury. A two-photon resonance in the four-wave mixing scheme is essential for a powerful cw Lyman-α source and is well investigated.

  18. A reliable cw Lyman-{alpha} laser source for future cooling of antihydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Kolbe, Daniel, E-mail: kolbed@uni-mainz.de; Beczkowiak, Anna; Diehl, Thomas; Koglbauer, Andreas; Sattler, Matthias; Stappel, Matthias; Steinborn, Ruth; Walz, Jochen [Johannes Gutenberg-Universitaet, Institut fuer Physik (Germany)

    2012-12-15

    We demonstrate a reliable continuous-wave (cw) laser source at the 1 S-2 P transition in (anti)hydrogen at 121.56 nm (Lyman-{alpha}) based on four-wave sum-frequency mixing in mercury. A two-photon resonance in the four-wave mixing scheme is essential for a powerful cw Lyman-{alpha} source and is well investigated.

  19. Two-step resonance ionization spectroscopy of Na atomic beam using cw and pulsed lasers

    International Nuclear Information System (INIS)

    Katsuragawa, H.; Minowa, T.; Shimazu, M.

    1988-01-01

    Two-step photoionization of sodium atomic beam has been carried out using a cw and a pulsed dye lasers. Sodium ions have been detected by a time of flight method in order to reduce background noise. With a proper power of the pulsed dye laser the sodium atomic beam has been irradiated by a resonant cw dye laser. The density of the sodium atomic beam is estimated to be 10 3 cm -3 at the ionization area. (author)

  20. Structural effects on electromagnetic flow coupler performance

    International Nuclear Information System (INIS)

    Aoyama, Goro; Yokota, Norikatsu; Mine, Masao; Watanabe, Takashi; Takuma, Tadasu; Takenaka, Kiyoshi.

    1992-01-01

    A prototype electromagnetic flow coupler was tested using 300degC liquid sodium to estimate the effect on performance of generator flow velocity, magnetic flux density, magnetic core length and bus bar length. Its performance was not affected by changes in fluid velocity and magnetic flux density up to 8.3 m/s and 0.51 T, respectively. Besides the experiments, a two-dimensional numerical analysis program based on Ohm's law and the current continuity equation was prepared to estimate the effects of magnetic core length and bus bar construction. The current transferred from the generator to the pump, the current transfer ratio, increased by lengthening the magnetic core being a maximum of 0.706 for a 100 mm core and 0.764 for a 300 mm core. The numerical results showed that the presence of the bus bar in the outer region of the magnetic core gave inferior performance to that in its absence. (author)

  1. Surface acoustic waves voltage controlled directional coupler

    Science.gov (United States)

    Golan, G.; Griffel, G.; Yanilov, E.; Ruschin, S.; Seidman, A.; Croitoru, N.

    1988-10-01

    An important condition for the development of surface wave integrated-acoustic devices is the ability to guide and control the propagation of the acoustic energy. This can be implemented by deposition of metallic "loading" channels on an anisotropic piezoelectric substrate. Deposition of such two parallel channels causes an effective coupling of acoustic energy from one channel to the other. A basic requirement for this coupling effect is the existence of the two basic modes: a symmetrical and a nonsymmetrical one. A mode map that shows the number of sustained modes as a function of the device parameters (i.e., channel width; distance between channels; material velocity; and acoustical exciting frequency) is presented. This kind of map can help significantly in the design process of such a device. In this paper we devise an advanced acoustical "Y" coupler with the ability to control its effective coupling by an externally applied voltage, thereby causing modulation of the output intensities of the signals.

  2. Efficient waveguide coupler based on metal materials

    Science.gov (United States)

    Wu, Wenjun; Yang, Junbo; Chang, Shengli; Zhang, Jingjing; Lu, Huanyu

    2015-10-01

    Because of the diffraction limit of light, the scale of optical element stays in the order of wavelength, which makes the interface optics and nano-electronic components cannot be directly matched, thus the development of photonics technology encounters a bottleneck. In order to solve the problem that coupling of light into the subwavelength waveguide, this paper proposes a model of coupler based on metal materials. By using Surface Plasmon Polaritons (SPPs) wave, incident light can be efficiently coupled into waveguide of diameter less than 100 nm. This paper mainly aims at near infrared wave band, and tests a variety of the combination of metal materials, and by changing the structural parameters to get the maximum coupling efficiency. This structure splits the plane incident light with wavelength of 864 nm, the width of 600 nm into two uniform beams, and separately coupled into the waveguide layer whose width is only about 80 nm, and the highest coupling efficiency can reach above 95%. Using SPPs structure will be an effective method to break through the diffraction limit and implement photonics device high-performance miniaturization. We can further compress the light into small scale fiber or waveguide by using the metal coupler, and to save the space to hold more fiber or waveguide layer, so that we can greatly improve the capacity of optical communication. In addition, high-performance miniaturization of the optical transmission medium can improve the integration of optical devices, also provide a feasible solution for the photon computer research and development in the future.

  3. Design of 250-MW CW RF system for APT

    International Nuclear Information System (INIS)

    Rees, D.

    1997-01-01

    The design for the RF systems for the APT (Accelerator Production of Tritium) proton linac will be presented. The linac produces a continuous beam power of 130 MW at 1300 MeV with the installed capability to produce up to a 170 MW beam at 1700 MeV. The linac is comprised of a 350 MHz RFQ to 7 MeV followed in sequence by a 700 MHz coupled-cavity drift tube linac, coupled-cavity linac, and superconducting (SC) linac to 1700 MeV. At the 1700 MeV, 100 mA level the linac requires 213 MW of continuous-wave (CW) RF power. This power will be supplied by klystrons with a nominal output power of 1.0 MW. 237 kystrons are required with all but three of these klystrons operating at 700 MHz. The klystron count includes redundancy provisions that will be described which allow the RF systems to meet an operational availability in excess of 95 percent. The approach to achieve this redundancy will be presented for both the normal conducting (NC) and SC accelerators. Because of the large amount of CW RF power required for the APT linac, efficiency is very important to minimize operating cost. Operation and the RF system design, including in-progress advanced technology developments which improve efficiency, will be discussed. RF system performance will also be predicted. Because of the simultaneous pressures to increase RF system reliability, reduce tunnel envelope, and minimize RF system cost, the design of the RF vacuum windows has become an important issue. The power from a klystron will be divided into four equal parts to minimize the stress on the RF vacuum windows. Even with this reduction, the RF power level at the window is at the upper boundary of the power levels employed at other CW accelerator facilities. The design of a 350 MHz, coaxial vacuum window will be presented as well as test results and high power conditioning profiles. The transmission of 950 kW, CW, power through this window has been demonstrated with only minimal high power conditioning

  4. 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.

  5. Grating-assisted surface acoustic wave directional couplers

    Science.gov (United States)

    Golan, G.; Griffel, G.; Seidman, A.; Croitoru, N.

    1991-07-01

    Physical properties of novel grating-assisted Y directional couplers are examined using the coupled-mode theory. A general formalism for the analysis of the lateral perturbed directional coupler properties is presented. Explicit expressions for waveguide key parameters such as coupling length, grating period, and other structural characterizations, are obtained. The influence of other physical properties such as time and frequency response or cutoff conditions are also analyzed. A plane grating-assisted directional coupler is presented and examined as a basic component in the integrated acoustic technology.

  6. Ultra-compact silicon nitride grating coupler for microscopy systems

    OpenAIRE

    Zhu, Yunpeng; Wang, Jie; Xie, Weiqiang; Tian, Bin; Li, Yanlu; Brainis, Edouard; Jiao, Yuqing; Van Thourhout, Dries

    2017-01-01

    Grating couplers have been widely used for coupling light between photonic chips and optical fibers. For various quantum-optics and bio-optics experiments, on the other hand, there is a need to achieve good light coupling between photonic chips and microscopy systems. Here, we propose an ultra-compact silicon nitride (SiN) grating coupler optimized for coupling light from a waveguide to a microscopy system. The grating coupler is about 4 by 2 mu m(2) in size and a 116 nm 1 dB bandwidth can be...

  7. Low-loss multimode interference couplers for terahertz waves

    Science.gov (United States)

    Themistos, Christos; Kalli, Kyriacos; Komodromos, Michael; Markides, Christos; Quadir, Anita; Rahman, B. M. Azizur; Grattan, Kenneth T. V.

    2012-04-01

    The terahertz (THz) frequency region of the electromagnetic spectrum is located between the traditional microwave spectrum and the optical frequencies, and offers a significant scientific and technological potential in many fields, such as in sensing, in imaging and in spectroscopy. Waveguiding in this intermediate spectral region is a major challenge. Amongst the various THz waveguides suggested, metal-clad plasmonic waveguides and specifically hollow core structures, coated with insulating material are the most promising low-loss waveguides used in both active and passive devices. Optical power splitters are important components in the design of optoelectronic systems and optical communication networks such as Mach-Zehnder Interferometric switches, polarization splitter and polarization scramblers. Several designs for the implementation of the 3dB power splitters have been proposed in the past, such as the directional coupler-based approach, the Y-junction-based devices and the MMI-based approach. In the present paper a novel MMI-based 3dB THz wave splitter is implemented using Gold/polystyrene (PS) coated hollow glass rectangular waveguides. The H-field FEM based full-vector formulation is used here to calculate the complex propagation characteristics of the waveguide structure and the finite element beam propagation method (FE-BPM) and finite difference time domain (FDTD) approach to demonstrate the performance of the proposed 3dB splitter.

  8. Mathematical characterization of continuous wave infrared stimulated luminescence signals (CW-IRSL) from feldspars

    International Nuclear Information System (INIS)

    Pagonis, V.; Phan, Huy; Goodnow, Rebecca; Rosenfeld, Sara; Morthekai, P.

    2014-01-01

    Continuous-wave infrared stimulated luminescence signals (CW-IRSL) from feldspars have been the subject of many experimental studies, due to their importance in luminescence dating and dosimetry. Accurate mathematical characterization of the shape of these CW-IRSL signals in feldspars is of practical and theoretical importance, especially in connection with “anomalous fading” of luminescence signals in dating studies. These signals are known to decay in a non-exponential manner and their exact mathematical shape as a function of stimulation time is an open research question. At long stimulation times the IRSL decay has been shown experimentally to follow a power law of decay, and previous researchers have attempted to fit the overall shape of these signals empirically using the well known Becquerel function (or compressed hyperbola decay law). This paper investigates the possibility of fitting CW-IRSL curves using either the Becquerel decay law, or a recently developed analytical equation based on localized electronic recombination of donor–acceptor pairs in luminescent materials. It is shown that both mathematical approaches can give excellent fits to experimental CW-IRSL curves, and the precision of the fitting process is studied by analyzing a series of curves measured using a single aliquot of a feldspar sample. Both fitting equations are solutions of differential equations involving numerically similar time dependent recombination probabilities k(t). It is concluded that both fitting equations provide approximately equivalent mathematical descriptions of the CW-IRSL curves in feldspars, and can be used as mathematical representations of the shape of CW-IRSL signals. - Highlights: • Feldspar CW-IRSL curves fitted using Becquerel decay law and new analytical equation. • Both mathematical approaches give excellent fits to experimental CW-IRSL curves. • Series of experimental CW-IRSL curves analyzed using both fitting expressions. • The time

  9. Thermal behaviour analysis of SRF cavities and superconducting HOM couplers

    International Nuclear Information System (INIS)

    Fouaidy, M.; Junquera, T.

    1993-01-01

    Two individual papers appear in this report, titled Thermal model calculations in superconducting RF cavities, and Thermal study of HOM couplers for superconducting RF cavities. Both were indexed separately for the INIS database. (R.P.)

  10. 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...

  11. Direct UV-written broadband directional broadband planar waveguide couplers

    DEFF Research Database (Denmark)

    Olivero, Massimo; Svalgaard, Mikael

    2005-01-01

    We report the fabrication of broadband directional couplers by direct UV-writing. The fabrication process is shown to be beneficial, robust and flexible. The components are compact and show superior performance in terms of loss and broadband operation.......We report the fabrication of broadband directional couplers by direct UV-writing. The fabrication process is shown to be beneficial, robust and flexible. The components are compact and show superior performance in terms of loss and broadband operation....

  12. Magnetic Shielding Design for Coupler of Wireless Electric Vehicle Charging Using Finite Element Analysis

    Science.gov (United States)

    Zhao, W. N.; Yang, X. J.; Yao, C.; Ma, D. G.; Tang, H. J.

    2017-10-01

    Inductive power transfer (IPT) is a practical and preferable method for wireless electric vehicle (EV) charging which proved to be safe, convenient and reliable. Due to the air gap between the magnetic coupler, the magnetic field coupling decreases and the magnetic leakage increases significantly compared to traditional transformer, and this may lead to the magnetic flux density around the coupler more than the safety limit for human. So magnetic shielding should be adding to the winding made from litz wire to enhance the magnetic field coupling effect in the working area and reduce magnetic field strength in non-working area. Magnetic shielding can be achieved by adding high-permeability material or high-conductivity material. For high-permeability material its magnetic reluctance is much lower than the surrounding air medium so most of the magnetic line goes through the high-permeability material rather than surrounding air. For high-conductivity material the eddy current in the material can produce reverse magnetic field to achieve magnetic shielding. This paper studies the effect of the two types of shielding material on coupler for wireless EV charging and designs combination shielding made from high-permeability material and high-conductivity material. The investigation of the paper is done with the help of finite element analysis.

  13. 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.

  14. HOM/LOM Coupler Study for the ILC Crab Cavity

    International Nuclear Information System (INIS)

    Xiao, L.; Li, Z.; Ko, K.

    2007-01-01

    The FNAL 9-cell 3.9GHz deflecting mode cavity designed for the CKM experiment was chosen as the baseline design for the ILC BDS crab cavity. The full 9-cell CKM cavity including the coupler end-groups was simulated using the parallel eigensolver Omega3P and scattering parameter solver S3P. It was found that both the notch filters for the HOM/LOM couplers are very sensitive to the notch gap, which is about 1.6MHz/micron and is more than 10 times more sensitive than the TTF cavity. It was also found in the simulation that the unwanted vertical π-mode (SOM) is strongly coupled to the horizontal 7π/9 mode which causes x-y coupling and reduces the effectiveness of the SOM damping. To meet the ILC requirements, the HOM/LOM couplers are redesigned to address these issues. With the new designs, the damping of the HOM/LOM modes is improved. The sensitivity of the notch filter for the HOM coupler is reduced by one order of magnitude. The notch filter for the LOM coupler is eliminated in the new design which significantly simplifies the geometry. In this paper, we will present the simulation results of the original CKM cavity and the progresses on the HOM/LOM coupler re-design and optimization

  15. Gaussian beam-to-slab waveguide coupler by graded index photonic crystal lens

    International Nuclear Information System (INIS)

    Bahari, B; Abrishamian, M S

    2013-01-01

    In this numerical study, a Gaussian beam-to-slab waveguide coupler for both modes of TM and TE has been studied. For this purpose, a concrete structure is suggested, in which the graded index photonic crystal lens and the slab waveguide are in the same structure composed of Si material, and can be fabricated with a single-step lithography process. For maximum power coupling, half-holes have been used as an input matching layer. Power coupling of 80% over a 450 nm bandwidth for the TM mode, and 60% over a 180 nm bandwidth for the TE mode is achieved. (paper)

  16. Ellipsoidal diffraction grating as output coupler for quasi-optical gyrotrons

    International Nuclear Information System (INIS)

    Hogge, J.P.; Cao, H.; Tran, T.M.; Tran, M.Q.; Paris, P.J.; Kasparek, W.

    1991-01-01

    The use of a diffraction grating arranged in the -1 Littrow mount as an output coupler for a quasi-optical Fabry-Perot resonator at microwave frequencies (100 GHz) was suggested in 1990. A planar grating with curvilinear grooves (in order to match the Littrow condition everywhere on the surface for a given Gaussian beam) gives a power coupling efficiency of 85% which is limited by the depolarization but gave approximately the same global efficiency because of distortion. We report low power tests on an improvement of the second scheme, based on curved grooves on an ellipsoidal surface, which gives a global efficiency of 94%. (author) 3 figs., 3 refs

  17. 1-W quasi-cw near-diffraction-limited semiconductor laser pumped optically by a fibre-coupled diode bar

    OpenAIRE

    Dhanjal, S.; Hoogland, S.; Roberts, J.S.; Hayward, R.A.; Clarkson, W.A.; Tropper, Anne

    2000-01-01

    We describe a diode-bar-pumped vertical-external-cavity surface-emitting semiconductor laser, which in quasi-cw operation emitted a peak power of >1 W at 1020 nm in a circular, near diffraction-limited beam.

  18. Optimization of the buffer layer of a side polished fiber slab coupler based on 3 D ADI beam propagation method

    International Nuclear Information System (INIS)

    Lee, Cherl Hee; Kim, Cheol; Park, Jae Hee

    2008-01-01

    A side polished fiber slab coupler has been widely applied to a sensor, which has the advantages of short response time, simple manufacturing process, and reusability as well as in line fiber component. A new type of a side polished fiber sensor providing remote sensing with an improved performance was also recently developed. The side polished fiber slab coupler is modeled as a fiber to planar waveguide coupler with four layers, including the fiber cladding, a buffer layer, planar waveguide and overlay material. The coupling effects by the buffer layer of a side polished fiber slab coupler are analyzed by using 3 dimensional alternating direction implicit (ADI)beam propagation method, where the refractive index and thickness of the buffer layer were tuned for efficient light coupling. The coupling is easily tuned and more occurred by the refractive index and thickness of the buffer layer for efficient coupling. This study tried to optimize the buffer layer parameters for achieving the desired light coupling and power transfer performance

  19. 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).

  20. Quasi-CW Laser Diode Bar Life Tests

    Science.gov (United States)

    Stephen, Mark A.; Krainak, Michael A.; Dallas, Joseph L.

    1997-01-01

    NASA's Goddard Space Flight Center is developing technology for satellite-based, high peak power, LIDAR transmitters requiring 3-5 years of reliable operation. Semi-conductor laser diodes provide high efficiency pumping of solid state lasers with the promise of long-lived, reliable operation. 100-watt quasi- CW laser diode bars have been baselined for the next generation laser altimeters. Multi-billion shot lifetimes are required. The authors have monitored the performance of several diodes for billions of shots and investigated operational modes for improving diode lifetime.

  1. Numerical simulation of waveguide input/output couplers for a planar mm-wave linac cavity

    International Nuclear Information System (INIS)

    Kang, Y.W.

    1994-01-01

    A double-sided planar mm-wave linear accelerating cavity structure has been studied. The input/output couplers for the accelerating cavity structure have been designed using the Hewlett-Packard High Frequency Structure Simulator (HFSS). The program is a frequency domain finite element 3-D field solver and can include matched port boundary conditions. The power transmission property of the structure is calculated in the frequency domain. The dimensions of the, coupling cavities and the irises at the input/output ports are adjusted to have the structure matched to rectangular waveguides. The field distributions in the accelerating structure for the 2π/3-mode traveling wave are shown

  2. 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...

  3. Broadband polymer microstructured THz fiber coupler with downdoped cores

    DEFF Research Database (Denmark)

    Nielsen, Kristian; Rasmussen, Henrik K.; Bang, Ole

    2010-01-01

    We demonstrate a broadband THz directional coupler based on a dual core photonic crystal fiber (PCF) design with mechanically down-doped core regions. For a center frequency of 1.3 THz we demonstrate a bandwidth of 0.65 THz.......We demonstrate a broadband THz directional coupler based on a dual core photonic crystal fiber (PCF) design with mechanically down-doped core regions. For a center frequency of 1.3 THz we demonstrate a bandwidth of 0.65 THz....

  4. Distributed grating-assisted coupler for optical all-dielectric electron accelerator

    Directory of Open Access Journals (Sweden)

    Zhiyu Zhang

    2005-07-01

    Full Text Available A Bragg waveguide consisting of multiple dielectric layers with alternating index of refraction becomes an excellent option to form electron accelerating structure powered by high power laser sources. It provides confinement of a synchronous speed-of-light mode with extremely low loss. However, laser field cannot be coupled into the structure collinearly with the electron beam. There are three requirements in designing input coupler for a Bragg electron accelerator: side coupling, selective mode excitation, and high coupling efficiency. We present a side-coupling scheme using a distributed grating-assisted coupler to inject the laser power into the waveguide. Side coupling is achieved by a grating with a period on the order of an optical wavelength. The phase matching condition results in resonance coupling thus providing selective mode excitation capability. The coupling efficiency is limited by profile matching between the outgoing beam and the incoming beam, which has normally a Gaussian profile. We demonstrate a nonuniform distributed grating structure generating an outgoing beam with a Gaussian profile, therefore, increasing the coupling efficiency.

  5. Cw operation of the FMIT RFQ accelerator

    International Nuclear Information System (INIS)

    Cornelius, W.D.

    1985-01-01

    Recently, we have achieved reliable cw operation of the Fusion Materials Irradiation Test (FMIT) radio-frequency quadrupole (RFQ) accelerator. In addition to the operational experiences in achieving this status, some of the modifications of the vacuum system, cooling system, and rf structure are discussed. Preliminary beam-characterization results are presented. 10 refs., 8 figs

  6. CW operation of the FMIT RFQ accelerator

    International Nuclear Information System (INIS)

    Cornelius, W.D.

    1984-01-01

    Experiences in attaining cw operation of the radio-frequency quadrupole for the Fusion Materials Irradiation Test facility are presented. Modifications of the vacuum system, changes in the rf structure, and operational experiences are discussed, as well as preliminary results of initial beam-characterization measurements. 4 references, 2 figures

  7. Cw rf operation of the FMIT RFQ

    International Nuclear Information System (INIS)

    Fazio, M.V.; Brandeberry, F.E.

    1985-01-01

    The 80-MHz RFQ for the Fusion Materials Irradiation Test Facility prototype accelerator has been rf conditioned for cw operation to the design field level of 17.5 MV/m (1.68 x Kilpatrick limit). Experimental results and operating experience will be discussed

  8. A CW Gunn diode bistable switching element.

    Science.gov (United States)

    Hurtado, M.; Rosenbaum, F. J.

    1972-01-01

    Experiments with a current-controlled bistable switching element using a CW Gunn diode are reported. Switching rates of the order of 10 MHz have been obtained. Switching is initiated by current pulses of short duration (5-10 ns). Rise times of the order of several nanoseconds could be obtained.

  9. Spectral filtering for CW searches

    International Nuclear Information System (INIS)

    D'Antonio, S; Frasca, S; Palomba, C

    2009-01-01

    In the hierarchical all-sky search method for periodic sources developed in the Virgo Collaboration, after the first incoherent step based on the Hough transform we have a number of candidates that must be analyzed using a much longer time baseline periodogram. In this step, we correct the signal power spread due to the Earth rotation, which becomes relevant for observation times greater than ∼1 sidereal day, using a bank of matched filters on the power spectrum. Describing the wave as the combination of a linearly polarized and a circularly polarized component, the spread depends on two parameters: the polarization angle of the linearly polarized wave component and the percentage of linear polarization. Here we discuss in detail the issue of how many filters must be built to properly cover the parameter space and give some implementation details of the procedure.

  10. Slot-coupled CW standing wave accelerating cavity

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shaoheng; Rimmer, Robert; Wang, Haipeng

    2017-05-16

    A slot-coupled CW standing wave multi-cell accelerating cavity. To achieve high efficiency graded beta acceleration, each cell in the multi-cell cavity may include different cell lengths. Alternatively, to achieve high efficiency with acceleration for particles with beta equal to 1, each cell in the multi-cell cavity may include the same cell design. Coupling between the cells is achieved with a plurality of axially aligned kidney-shaped slots on the wall between cells. The slot-coupling method makes the design very compact. The shape of the cell, including the slots and the cone, are optimized to maximize the power efficiency and minimize the peak power density on the surface. The slots are non-resonant, thereby enabling shorter slots and less power loss.

  11. Design of a 300 GHz Broadband TWT Coupler and RF-Structure

    CERN Document Server

    Krawczyk, F L

    2004-01-01

    Recent LANL activities in millimeter wave structures focus on 94 and 300 GHz structures. They aim at power generation from low power (100–2000 W) with a round electron beam (120 kV, 0.1–1.0 A) to high power (2–100 kW) with a sheet beam structure (120 kV, 20 A). Applications cover basic research, radar and secure communications and remote sensing of biological and chemical agents. In this presentation the design and cold-test measurements of a 300 GHz RF-structure with a broadband (>6% bandwidth) power coupler are presented. The design choice of two input/output waveguides, a special coupling region and the structure parameters themselves are presented. As a benchmark also a scaled up version at 10 GHz was designed and measured. These results will also be presented.

  12. An 8–18 GHz broadband high power amplifier

    International Nuclear Information System (INIS)

    Wang Lifa; Yang Ruixia; Li Yanlei; Wu Jingfeng

    2011-01-01

    An 8–18 GHz broadband high power amplifier (HPA) with a hybrid integrated circuit (HIC) is designed and fabricated. This HPA is achieved with the use of a 4-fingered micro-strip Lange coupler in a GaAs MMIC process. In order to decrease electromagnetic interference, a multilayer AlN material with good heat dissipation is adopted as the carrier of the power amplifier. When the input power is 25 dBm, the saturated power of the continuous wave (CW) outputted by the power amplifier is more than 39 dBm within the frequency range of 8–13 GHz, while it is more than 38.6 dBm within other frequency ranges. We obtain the peak power output, 39.4 dBm, at the frequency of 11.9 GHz. In the whole frequency band, the power-added efficiency is more than 18%. When the input power is 18 dBm, the small signal gain is 15.7 ± 0.7 dB. The dimensions of the HPA are 25 × 15 × 1.5 mm 3 . (semiconductor integrated circuits)

  13. Nonclassical properties of a contradirectional nonlinear optical coupler

    Energy Technology Data Exchange (ETDEWEB)

    Thapliyal, Kishore [Jaypee Institute of Information Technology, A-10, Sector-62, Noida, UP-201307 (India); Pathak, Anirban, E-mail: anirban.pathak@gmail.com [Jaypee Institute of Information Technology, A-10, Sector-62, Noida, UP-201307 (India); RCPTM, Joint Laboratory of Optics of Palacky University and Institute of Physics of Academy of Science of the Czech Republic, Faculty of Science, Palacky University, 17. listopadu 12, 771 46 Olomouc (Czech Republic); Sen, Biswajit [Department of Physics, Vidyasagar Teachers' Training College, Midnapore 721101 (India); Perřina, Jan [RCPTM, Joint Laboratory of Optics of Palacky University and Institute of Physics of Academy of Science of the Czech Republic, Faculty of Science, Palacky University, 17. listopadu 12, 771 46 Olomouc (Czech Republic); Department of Optics, Palacky University, 17. listopadu 12, 771 46 Olomouc (Czech Republic)

    2014-10-24

    We investigate the nonclassical properties of output fields propagated through a contradirectional asymmetric nonlinear optical coupler consisting of a linear waveguide and a nonlinear (quadratic) waveguide operated by second harmonic generation. In contrast to the earlier results, all the initial fields are considered weak and a completely quantum-mechanical model is used here to describe the system. Perturbative solutions of Heisenberg's equations of motion for various field modes are obtained using Sen–Mandal technique. Obtained solutions are subsequently used to show the existence of single-mode and intermodal squeezing, single-mode and intermodal antibunching, two-mode and multi-mode entanglement in the output of contradirectional asymmetric nonlinear optical coupler. Further, existence of higher order nonclassicality is also established by showing the existence of higher order antibunching, higher order squeezing and higher order entanglement. Variation of observed nonclassical characters with different coupling constants and phase mismatch is discussed. - Highlights: • Nonclassicalities in fields propagating through a directional coupler is studied. • Completely quantum-mechanical description of the coupler is provided. • Analytic solutions of Heisenberg equations of motion for various modes are obtained. • Existence of lower order and higher order entanglement is shown. • Variation of nonclassicalities with phase-mismatch and coupling constants is studied.

  14. Coupler tuning for constant gradient travelling wave accelerating structures

    International Nuclear Information System (INIS)

    Guo Xingkun; Ma Yanyun; Wang Xiulong

    2013-01-01

    The method of the coupler tuning for the constant gradient traveling wave accelerating structure was described and the formula of coupling coefficient p was deduced on the basis of analyzing the existing methods for the constant impedance traveling wave accelerating structures and coupling-cavity chain equivalent circuits. The method and formula were validated by the simulation result by CST and experiment data. (authors)

  15. 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.

  16. Analysis and design of arrayed waveguide gratings with MMI couplers.

    Science.gov (United States)

    Munoz, P; Pastor, D; Capmany, J

    2001-09-24

    We present an extension of the AWG model and design procedure described in [1] to incorporate multimode interference, MMI, couplers. For the first time to our knowledge, a closed formula for the passing bands bandwidth and crosstalk estimation plots are derived.

  17. Directional couplers using long-range surface plasmon polariton waveguides

    DEFF Research Database (Denmark)

    Boltasseva, Alexandra; Bozhevolnyi, Sergey I.

    2006-01-01

    14-nm-thick stripes and a wavelength of 1550 urn, LR-SPP propagation loss is determined for the stripe widths varying from 2 to 12 mu m and is found to be similar to 7 and 5 dB/cm for 10- and 4-mu m-wide stripes, respectively. For the directional couplers based on 14-nm-thick and 8-mu m-wide gold...... stripes and a wavelength of 1570 nm, the coupling lengths of 4.1, 1.9, and 0.8 mm are found for the respective waveguide separations of 8, 4, and 0 mu m. We model the LR-SPP-based directional couplers using the effective-refractive-index method and obtain a good agreement with the experimental results....... The transmission spectra of LR-SPP-based directional couplers are presented demonstrating an efficient (similar to 30 dB) separation of different telecom wavelength bands. Various possibilities for dynamic control of wavelength division/multiplexing with LRSPP-based directional couplers that utilize the thermo...

  18. Pulsed x-ray induced attenuation measurements of single mode optical fibers and coupler materials

    International Nuclear Information System (INIS)

    Johan, A.; Charre, P.

    1994-01-01

    Pulsed X-ray induced transient radiation attenuation measurements of single mode optical fibers have been performed versus total dose, light wavelength, optical power and fiber coil diameter in order to determine the behavior of parameters sensitive to ionizing radiation. The results did not show any photobleaching phenomenon and the attenuation was found independent of the spool diameter. As expected, transient attenuation was lower for higher wave-lengths. The recovery took place in the millisecond range and was independent of total dose, light wavelength and optical power. In optical modules and devices a large range of behaviors was observed according to coupler material i.e., Corning coupler showed a small peak attenuation that remained more than one day later; on the other hand LiTaO 3 material experienced an order of magnitude higher peak attenuation and a recovery in the millisecond range. For applications with optical fibers and integrated optics devices the authors showed that in many cases the optical fiber (length above 100 m) is the most sensitive device in a transient ionizing radiation field

  19. Light scattering from thermal density fluctuations using a CW-CO2-laser and heterodyne detection

    International Nuclear Information System (INIS)

    Massig, J.H.

    1978-01-01

    The ion feature in the scattered light spectrum of an arc plasma was measured using heterodyne detection. A low-power CW-CO 2 -laser was employed. The weak signals were discriminated against noise by lock-in technique. (orig.) [de

  20. Status of the development of the EU 170 GHz/1 MW/CW gyrotron

    Energy Technology Data Exchange (ETDEWEB)

    Pagonakis, Ioannis Gr., E-mail: ioannis.pagonakis@kit.edu [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Albajar, Ferran [The European Joint Undertaking for ITER and The Development of Fusion Energy, Barcelona (Spain); Alberti, Stefano [École Polytechnique Fédérale de Lausanne, Centre de Recherches en Physique des Plasmas (CRPP), Lausanne (Switzerland); Avramidis, Konstantinos [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Bonicelli, Tullio [The European Joint Undertaking for ITER and The Development of Fusion Energy, Barcelona (Spain); Braunmueller, Falk [École Polytechnique Fédérale de Lausanne, Centre de Recherches en Physique des Plasmas (CRPP), Lausanne (Switzerland); Bruschi, Alex [Plasma Physics Institute, National Research Council of Italy, Milano (Italy); Chelis, Ioannis [School of Electrical and Computer Engineering, National Technical University of Athens (Greece); Cismondi, Fabio [The European Joint Undertaking for ITER and The Development of Fusion Energy, Barcelona (Spain); Gantenbein, Gerd [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Hermann, Virgile [Thales Electron Devices (TED), Vélizy-Villacoublay (France); Hesch, Klaus [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Hogge, Jean-Philippe [École Polytechnique Fédérale de Lausanne, Centre de Recherches en Physique des Plasmas (CRPP), Lausanne (Switzerland); Jelonnek, John; Jin, Jianbo; Illy, Stefan [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Ioannidis, Zisis C. [Faculty of Physics, National and Kapodistrian University of Athens (Greece); Kobarg, Thorsten [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); and others

    2015-10-15

    The progress in the development of the European 170 GHz, 1 MW/CW gyrotron for electron cyclotron heating & current drive (ECH&CD) on ITER is reported. A continuous wave (CW) prototype is being manufactured by Thales Electron Devices (TED), France, while a short-pulse (SP) prototype gyrotron is in parallel under manufacture at Karlsruhe Institute of Technology (KIT), with the purpose of validating the design of the CW industrial prototype components. The fabrication of most of the sub-assemblies of the SP prototype has been completed. In a first step, an existing magnetron injection gun (MIG) available at KIT was used. Despite this non-ideal configuration, the experiments provided a validation of the design, substantiated by an excellent agreement with numerical simulations. The tube, operated without a depressed collector, is able to produce more than 1 MW of output power with efficiency in excess of 30%, as expected, and compatible with the ITER requirements.

  1. Calculation of the local power peaking near WWER-440 control assemblies with Hf plates

    International Nuclear Information System (INIS)

    Hegyi, Gy.; Hordosy, G.; Kereszturi, A.; Maraszy, Cs.; Temesvari, E.

    2003-01-01

    The original coupler design of the WWER-440 assemblies had the following well known deficiency: The relatively large amount of water in the coupler between the absorber and fuel port of the control assembly can cause undesirably sharp power peaking in the fuel rods next to the coupler. The power peaking can be especially high after control rod withdrawal when the coupler reached low burnup level region of the adjacent assembly. The modernized coupler design overcomes the original problem by applying a thin Hf plate in the critical region. The very complicated structure of the coupler requires the verification of the core design methods by high precision 3D Monte Carlo calculations. The paper presents an MCNP reference calculation on the control rod coupler benchmark with Hf absorber plates. The benchmark solution with the KARATE-440 code system is also presented. The need for treating the Hf burnout in the reflector region is investigated (Authors)

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

    DEFF Research Database (Denmark)

    Ciric, Dejan; Hammershøi, Dorte

    2005-01-01

    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......, the differences among earphones as well as between human ears and the coupler affect the results of audiometric measurements inducing uncertainty. The influence of these differences is examined by investigating the sound transmission in both human ears and standardized coupler loaded by different audiometric......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...

  3. Stable CW Single-Frequency Operation of Fabry-Perot Laser Diodes by Self-Injection Phase Locking

    Science.gov (United States)

    Duerksen, Gary L.; Krainak, Michael A.

    1999-01-01

    Previously, single-frequency semiconductor laser operation using fiber Bragg gratings has been achieved by two methods: 1) use of the FBG as the output coupler for an anti-reflection-coated semiconductor gain element'; 2) pulsed operation of a gain-switched Fabry-Perot laser diode with FBG-optical and RF-electrical feedback. Here, we demonstrate CW single frequency operation from a non-AR coated Fabry-Perot laser diode using only FBG optical feedback. We coupled a nominal 935 run-wavelength Fabry-Perot laser diode to an ultra narrow band (18 pm) FBG. When tuned by varying its temperature, the laser wavelength is pulled toward the centerline of the Bragg grating, and the spectrum of the laser output is seen to fall into three discrete stability regimes as measured by the side-mode suppression ratio.

  4. Caries like lesion initiation in sound enamel following CW CO2 laser irradiation: an in vitro study

    International Nuclear Information System (INIS)

    Nafie, A.; Issam, A.; Ali, M. S. R.

    2005-01-01

    This Study aimed to asses the caries - preventive potential of various CW CO 2 laser parameters, and to explore the effect of the laser power density, and the exposure time on the varies inhibition activity. Materials and Methods: Extracted human premolar teeth were irradiated with three different power densities (7.95, 15.9 and 31.8) W/Cm 2 for three different exposure times (0.2, 0.4 and 0.8) sec of 10.6 μm CW CO 2 laser. All teeth were subjected to caries like lesion formation by 3.5 pH lactic acid for 21 days. The teeth after that were sectioned into ground cross section and the lesion depths were measured using a graticule polarizing microscope. CW CO 2 laser preventive treatments inhibit caries like lesion progression up to 44%. This effect was improved with: (1) Increased power density for each of the three exposure times. (2) Decreased exposure time for each of the three power densities within the limits of the previously listed laser parameters. Conclusion: (1) short exposure time of CW CO 2 laser results in a significant inhibition of the enamel caries like lesion formation. (2) The inhibitory effect depends upon the power density and the exposure time of the laser beam. (3) The optimal CW CO 2 laser parameters used for caries inhibition purpose is achieved with approximately 30 W/Cm 2 power density and 0.2 sec exposure time. (author)

  5. CW Laser radar for combustion diagnostics

    Directory of Open Access Journals (Sweden)

    Malmqvist Elin

    2018-01-01

    Full Text Available A CW-laser radar system developed for combustion diagnostics is described. The system is based on triangulation to attain range information. A portable system has been constructed and here we show some result from measurements in various flames, for example Rayleigh scattering thermometry and monitoring of particle distributions with high temporal and spatial resolution. The concept can equally well be based on pulsed lasers, allowing suppression of background emission through gated detection.

  6. Diode-pumped quasi-three-level CW Nd:CLNGG and Nd:CNGG lasers.

    Science.gov (United States)

    He, Kunna; Wei, Zhiyi; Li, Dehua; Zhang, Zhiguo; Zhang, Huaijin; Wang, Jiyang; Gao, Chunqing

    2009-10-12

    We have demonstrated what is to our knowledge the first quasi-three-level CW Nd:CLNGG laser with simple linear resonator. When the pump power was 18.2 W, a maximum output power of 1.63 W was obtained at the dual-wavelength of 935 nm and 928 nm. The optical-to-optical conversion efficiency was 9.0% and the slope efficiency was 11.5%. Lasing characteristics of a quasi-three-level CW Nd:CNGG laser were also investigated. A maximum output power of 1.87 W was obtained at the single-wavelength of 935 nm with 15.2 W pump power, corresponding to an optical-to-optical conversion efficiency of 12.3% and a slope efficiency of 15.6%.

  7. Development of an optical resonator with high-efficient output coupler for the JAERI far-infrared free-electron laser

    International Nuclear Information System (INIS)

    Nagai, Ryoji; Hajima, Ryoichi; Nishimori, Nobuyuki; Sawamura, Masaru; Kikuzawa, Nobuhiro; Shizuma, Toshiyuki; Minehara, Eisuke

    2001-01-01

    An optical resonator with a high-efficient output coupler was developed for the JAERI far-infrared free-electron laser. The optical resonator is symmetrical near-concentric geometry with an insertable scraper output coupler. As a result of the development of the optical resonator, the JAERI-FEL has been successfully, lased with averaged power over 1 kW. Performance of the optical resonator with the output coupler was evaluated at optical wavelength of 22 μm by using an optical mode calculation code. The output coupling and diffractive loss with a dominant eigen-mode of the resonator were calculated using an iterative computation called Fox-Li procedure. An efficiency factor of the optical resonator was introduced for the evaluation of the optical resonator performance. The efficiency factor was derived by the amount of the output coupling and diffractive loss of the optical resonator. It was found that the optical resonator with the insertable scraper coupler was the most suitable to a high-power and high-efficient far-infrared free-electron laser. (author)

  8. Design of electro-absorption modulator with tapered-mode coupler on the GeSi layer

    International Nuclear Information System (INIS)

    Li, Ym; Cheng, Bw

    2013-01-01

    A tapered-mode coupler integrated GeSi electro-absorption (EA) modulator is investigated theoretically. To improve the parameter insensitivity and modulation efficiency of the GeSi EA modulator based on evanescent coupling, a tapered coupler on the GeSi layer is introduced in our design. The two coupling mechanisms in our suggested structure are compared. Both the beam propagation method (BPM) calculation and coupling mode theory show almost 100% power transfer from the bottom rib waveguide to the GeSi layer. After a series of designs of the tapered coupler, we get a modulator with the advantages of both evanescent-coupling modulators (Feng et al 2011 Opt. Express 19 7062–7, Feng et al 2012 Opt. Express 20 22224–32, Liu et al 2008 Nature Photon. 2 433–7, Liu et al 2007 Opt. Express 15 623–8) and butt-coupling modulators (Lim et al 2011 Opt. Express 19 5040–6), that are ease of fabrication, low coupling loss, performance stability and high modulation efficiency. (paper)

  9. Ceramic Power Extractor Design at 15.6 GHz

    CERN Document Server

    Smirnov, Alexei Yu; Yi, Rong; Yu, David

    2005-01-01

    Power extractor and coupler designs developed for an experiment planned at the 12th beam harmonic of the upgraded Advanced Wakefield Accelerator (AWA) facility is described. New features are an upstream HOM dielectric damper with additional tapering, and a single-port coupler considered in two variants. Performance analysis includes coupler geometric tolerances, overvoltage, dipole mode wake and BBU; and wakefield losses induced in the damper.

  10. Low-crosstalk orbital angular momentum fiber coupler design.

    Science.gov (United States)

    Zhang, Zhishen; Gan, Jiulin; Heng, Xiaobo; Li, Muqiao; Li, Jiong; Xu, Shanhui; Yang, Zhongmin

    2017-05-15

    A fiber coupler for low-crosstalk orbital angular momentum mode beam splitter is proposed with the structure of two separate and parallel microfibers. By properly setting the center-to-center distance between microfibers, the crosstalk is less than -20 dB, which means that the purity of the needed OAM mode in output port is higher than 99%. For a fixed overlapping length, high coupling efficiency (>97%) is achieved in 1545-1560 nm. The operating wavelength is tuned to the whole C-band by using the thermosensitive liquid. So the designed coupler can achieve the tunable coupling ratio over the whole C-band, which is a prospective component for the further OAM fiber system.

  11. Very short intracavity directional coupler for high-speed communication

    Science.gov (United States)

    Griffel, Giora

    1993-07-01

    We propose a novel intracavity modulator/switch that consists of a directional-coupler located inside a Fabry-Perot cavity. The back mirror of the cavity has a unit reflectivity so that both input and output signals are at the same side. In this way we obtain a two-port, single side element, with coupling length of 83.5 μm, which is the shortest modulation coupler proposed so far. The upper frequency limit due to photon lifetime is 275 GHz, which is well over the bandwidth constraints of microwave lumped structures. A unified approach for the analysis of this device and other similar structures is presented and discussed.

  12. A CW 4-rod RFQ for deuterons; Ein Hochleistungs-RFQ-Beschleuniger fuer Deuteronen

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, P.

    2007-06-15

    A four-rod RFQ accelerator has been built which operates in CW mode with a power consumption of 250 kW. The assembly of a high power RFQ structure requires a precise mechanical alignment and field tuning of the electrode field. The field distribution must be very flat to enable a proper operation with few losses. Adjusting of the field distribution is critical in long structures. (orig.)

  13. Quantum superchemistry in an output coupler of coherent matter waves

    International Nuclear Information System (INIS)

    Jing, H.; Cheng, J.

    2006-01-01

    We investigate the quantum superchemistry or Bose-enhanced atom-molecule conversions in a coherent output coupler of matter waves, as a simple generalization of the two-color photoassociation. The stimulated effects of molecular output step and atomic revivals are exhibited by steering the rf output couplings. The quantum noise-induced molecular damping occurs near a total conversion in a levitation trap. This suggests a feasible two-trap scheme to make a stable coherent molecular beam

  14. Finite element analysis and frequency shift studies for the bridge coupler of the coupled cavity linear accelerator of the spallation neutron source.

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Z. (Zukun)

    2001-01-01

    The Spallation Neutron Source (SNS) is an accelerator-based neutron scattering research facility. The linear accelerator (linac) is the principal accelerating structure and divided into a room-temperature linac and a superconducting linac. The normal conducting linac system that consists of a Drift Tube Linac (DTL) and a Coupled Cavity Linac (CCL) is to be built by Los Alamos National Laboratory. The CCL structure is 55.36-meters long. It accelerates H- beam from 86.8 Mev to 185.6 Mev at operating frequency of 805 MHz. This side coupled cavity structure has 8 cells per segment, 12 segments and 11 bridge couplers per module, and 4 modules total. A 5-MW klystron powers each module. The number 3 and number 9 bridge coupler of each module are connected to the 5-MW RF power supply. The bridge coupler with length of 2.5 {beta}{gamma} is a three-cell structure and located between the segments and allows power flow through the module. The center cell of each bridge coupler is excited during normal operation. To obtain a uniform electromagnetic filed and meet the resonant frequency shift, the RF induced heat must be removed. Thus, the thermal deformation and frequency shift studies are performed via numerical simulations in order to have an appropriate cooling design and predict the frequency shift under operation. The center cell of the bridge coupler also contains a large 4-inch slug tuner and a tuning post that used to provide bulk frequency adjustment and field intensity adjustment, so that produce the proper total field distribution in the module assembly.

  15. Low Loss 1×2 Optical Coupler Based on Cosine S-bend with Segmented Waveguides

    Science.gov (United States)

    Yulianti, Ian; Sahmah, Abu; Supa'at, M.; Idrus, Sevia M.; Ridwanto, Muhammad; Al-hetar, Abdulaziz M.

    2011-05-01

    This paper presents an optimization of 1×2 polymer Y-junction optical coupler. The optimized optical coupler comprises straight polymer waveguide as the input waveguide, tapered waveguide, modified cosine S-bend and linear waveguide. At the branching point, N short waveguides with small width are introduced to reduce evanescent field. At operating wavelength of 1550 nm the excess loss of the coupler is ˜0.18 dB. In term of polarization dependence loss (PDL), the proposed coupler also shows a good performance with PDL value of less than 0.015 dB for wavelength range of 1470 nm-1550 nm. The proposed coupler could reduce excess loss more than 25% compared to conventional Y junction optical coupler.

  16. Substrate integrated waveguide (SIW 3 dB coupler for K-Band applications

    Directory of Open Access Journals (Sweden)

    Khalid Nurehansafwanah

    2017-01-01

    Full Text Available This paper presented a designed coupler by using Rogers RO4003C with thickness (h 0.508 mm and relative permittivity (εr 3.55. The four port network coupler operates in K-band (18-27 GHz and design by using substrate integrated waveguide (SIW method. The reflection coefficient and isolation coefficient of propose Substrate Integrated Waveguide (SIW coupler is below than -10 dB. Meanwhile the coupler requirements are phase shift 90° between coupled port and output. SIW are high performance broadband interconnects with excellent immunity to electromagnetic interference and suitable for use in microwave and communication electronics, as well as increase bandwidth systems. The designs of coupler are investigated using CST Microwave Studio simulation tool. This proposed couplers are varied from parameters that cover the frequency range (21 -24 GHz and better performance of scattering (S-parameter.

  17. Diode-pumped cw Nd:YAG three-level laser at 869 nm.

    Science.gov (United States)

    Lü, Yanfei; Xia, Jing; Cheng, Weibo; Chen, Jifeng; Ning, Guobin; Liang, Zuoliang

    2010-11-01

    We report for the first time (to our knowledge) a diode-pumped Nd:YAG laser emitting at 869 nm based on the (4)F(3/2)-(4)I(9/2) transition, generally used for a 946 nm emission. Power of 453 mW at 869 nm has been achieved in cw operation with a fiber-coupled laser diode emitting 35.4 W at 809 nm. Intracavity second-harmonic generation in the cw mode has also been demonstrated with power of 118 mW at 435 nm by using a BiB(3)O(6) nonlinear crystal. In our experiment, we used a LiNbO(3) crystal lens to complement the thermal lens of the laser rod, and we obtained good beam quality and high output power stability.

  18. Diode-pumped CW Nd:SGG laser at 1070 nm

    International Nuclear Information System (INIS)

    Liang, W; Sun, G C; Yu, X; Li, B Z; Jin, G Y

    2011-01-01

    We report for the first time (to our knowledge) a diode-pumped Nd:SGG laser emitting at 1070 nm. A power of 1.23 W at 1070 nm has been achieved in continuous-wave (CW) operation with a fiber-coupled laser diode emitting 18.2 W at 806 nm. Intracavity second-harmonic generation (SHG) in CW mode has also been demonstrated with a power of 328 mW at 535 nm by using a LiB 3 O 5 (LBO) nonlinear crystal. The green beam quality factor M 2 was less than 1.22. The green power stability was less 2.5% in 4 hour

  19. Design and fabrication of multimode interference couplers based on digital micro-mirror system

    Science.gov (United States)

    Wu, Sumei; He, Xingdao; Shen, Chenbo

    2008-03-01

    Multimode interference (MMI) couplers, based on the self-imaging effect (SIE), are accepted popularly in integrated optics. According to the importance of MMI devices, in this paper, we present a novel method to design and fabricate MMI couplers. A technology of maskless lithography to make MMI couplers based on a smart digital micro-mirror device (DMD) system is proposed. A 1×4 MMI device is designed as an example, which shows the present method is efficient and cost-effective.

  20. A calculation method for RF couplers design based on numerical simulation by microwave studio

    International Nuclear Information System (INIS)

    Wang Rong; Pei Yuanji; Jin Kai

    2006-01-01

    A numerical simulation method for coupler design is proposed. It is based on the matching procedure for the 2π/3 structure given by Dr. R.L. Kyhl. Microwave Studio EigenMode Solver is used for such numerical simulation. the simulation for a coupler has been finished with this method and the simulation data are compared with experimental measurements. The results show that this numerical simulation method is feasible for coupler design. (authors)

  1. A cw 4-rod RFQ linac

    International Nuclear Information System (INIS)

    Fujisawa, Hiroshi

    1994-01-01

    A cw 4-rod RFQ linac system has been designed, constructed, and tested as an accelerator section of a MeV-class ion implanter system. The tank diameter is only 60 cm for 34 MHz operating frequency. An equally spaced arrangement of the RFQ electrode supporting plates is proved to be suitable for a low resonant frequency 4-rod RFQ structure. The RFQ electrode cross section is not circular but rectangular to make the handling and maintenance of the electrodes easier. The machining of the electrode is done three dimensionally. Second order corrections in the analyzing magnet of the LEBT (Low Energy Beam Transport) section assure a better transmission through and the matching to the RFQ. A new approach is introduced to measure the rf characteristics of the 4-rod RFQ. This method requires only a few capacitors and a network analyzer. Both the rf and thermal stability of the 4-rod RFQ are tested up to cw 50 kW. Beam experiments with several ions confirm the acceleration of beams to the goal energy of 83 keV/u. The ion beam intensities obtained at the RFQ output for He + , N 2+ , and C + are 32, 13, and 220 pμA, respectively. The measured beam transmissions of >80% agree with the PARMTEQ calculations. The ion implantation method also gives definitive information on the energies of an RFQ output beam. ((orig.))

  2. 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.......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....

  3. Broadband photonic crystal fiber coupler with polarization selection of coupling ratio

    Science.gov (United States)

    Jaroszewicz, Leszek R.; Stasiewicz, Karol A.; Marć, Paweł; Szymański, Michał

    2010-09-01

    In the paper a new broadband photonic crystal fiber coupler is presented. The proper application of the biconical taper technology has been used for manufacturing the coupler without air holes collapse in LMA10 fiber (NKT Photonics Crystal). This coupler, operates in the weakly coupling condition, protects coupling operation in range from 900 nm to 1700 nm. The coupling ratio between output arms is depending on wavelength and can be tuning by selection the proper input state of polarization. It gives opportunity to use the broadband crystal fiber coupler in many applications in which it is necessary to tune a coupling between output arms during the measurement.

  4. High-power actively Q-switched single-mode 1342 nm Nd:YVO4 ring laser, injection-locked by a cw single-frequency microchip laser.

    Science.gov (United States)

    Koch, Peter; Bartschke, Juergen; L'huillier, Johannes A

    2015-11-30

    In this paper we report on the realization of a single-mode Q-switched Nd:YVO4 ring laser at 1342 nm. Unidirectional and single-mode operation of the ring laser is achieved by injection-locking with a continuous wave Nd:YVO4 microchip laser, emitting a single-frequency power of up to 40 mW. The ring laser provides a single-mode power of 13.9 W at 10 kHz pulse repetition frequency with a pulse duration of 18.2 ns and an excellent beam quality (M2 laser, a power of 8.7 W at 671 nm with a pulse duration of 14.8 ns and a beam propagation factor of M2 < 1.1 is obtained. The 671 nm radiation features a long-term spectral width of 75 MHz.

  5. CW and femtosecond operation of a diode-pumped Yb:BaY(2)F(8) laser.

    Science.gov (United States)

    Galzerano, G; Coluccelli, N; Gatti, D; Di Lieto, A; Tonelli, M; Laporta, P

    2010-03-15

    We report for the first time on laser action of a diode-pumped Yb:BaY(2)F(8) crystal. Both CW and femtosecond operations have been demonstrated at room-temperature conditions. A maximum output power of 0.56 W, a slope efficiency of 34%, and a tunability range from 1013 to 1067 nm have been obtained in CW regime. Transform-limited pulse trains with a minimum duration of 275 fs, an average power of 40 mW, and a repetition rate of 83 MHz have been achieved in a passive mode-locked regime using a semiconductor saturable absorber mirror.

  6. Photonic crystal fibers for supercontinuum generation pumped by a gain-switched CW fiber laser

    DEFF Research Database (Denmark)

    Larsen, Casper; Noordegraaf, Danny; Hansen, Kim P.

    2012-01-01

    Supercontinuum generation in photonics crystal fibers (PCFs) pumped by CW lasers yields high spectral power density and average power. However, such systems require very high pump power and long nonlinear fibers. By on/off modulating the pump diodes of the fiber laser, the relaxation oscillations...... of the laser can be exploited to enhance the broadening process. The physics behind the supercontinuum generation is investigated by sweeping the fiber length, the zero dispersion wavelength, and the fiber nonlinearity. We show that by applying gain-switching a high average output power of up to 30 W can...

  7. Micromachining for Si etching using CW CO_2 laser

    International Nuclear Information System (INIS)

    Al-Hawat, Sh.; Naddaf, M.; Al-Sadat, W.; Wiess, Sh.

    2015-01-01

    Many experiments were carried out to achieve etching for silicon samples located on glass substrate (Pyrex or Quartz) using CW CO_2 laser under treating conditions which were in the case of linear scanning as: the power was 35-47 W, the number of round trips was 10-60 and the linear scanning speed was 17-75 mm/s, and in the case of fixed sample they were as: the power was 40 W and the exposure time was between 2-6 min. The obtained results were different depending on the form of etching and its quality, according to the applied treating conditions on the silicon samples, taking the treated silicon surface attached directly to the glass substrate surface or taking the opposite side of the silicon sample. The etching of the first type was easy to get, but the second one was more difficult to obtain, which requires very strong conditions. The best of these results were recorded using a quartz substrate under treating conditions: the laser power was 42.5 W, the number of round trips was 30, and the scanning speed was 75 mm/s, so the etching was limited to separate spots produced on the surface of the sample. In the all cases, the pictures of spots and lines formed on treated Si samples were taken using scanning electron microscope (SEM) for both sides of the studied samples.(author)

  8. Micromachining for Si etching using CW CO 2 laser

    International Nuclear Information System (INIS)

    Hawat, Sh.; Naddaf, M.; Al-Sadat, W.; Weiss, Sh.

    2012-08-01

    Many experiments were carried out to achieve etching for silicon samples located on glass substrate (Pyrex or Quartz) using Cw CO 2 laser under treating conditions which were in the case of linear scanning as: the power was 35-47 W, the number of round trips was 10-60 and the linear scanning speed was 17-75 mm/s, and in the case of fixed sample they were as: the power was 40 W and the exposure time was between 2-6 min. The obtained results were different depending on the form of etching and its quality, according to the applied treating conditions on the silicon samples, taking the treated silicon surface attached directly to the glass substrate surface or taking the opposite side of the silicon sample. The etching of the first type was easy to get, but the second one was more difficult to obtain, which requires very strong conditions. The best of these results were recorded using a quartz substrate under treating conditions: the laser power was 42.5 W, the number of round trips was 30, and the scanning speed was 75 mm/s, so the etching was limited to separate spots produced on the surface of the sample. In the all cases, the pictures of spots and lines formed on treated Si samples were taken using scanning electron microscope (SEM) for both sides of the studied samples. (authors)

  9. USING THE SCRAP TIRES TO PRODUCE A FLEXIBLE COUPLER

    Directory of Open Access Journals (Sweden)

    Tahsean A. Hussain

    2018-01-01

    Full Text Available The scrap tires considered a problematic source of waste, the old rubber tires causes a big environmental problem that is need much money and effort to disposes it safely. In Iraq there are more than two million used tires disposed to the environment annually. one of the tire’s recycling methods is the use of tire layers to produce a new rubber parts used in the engineering and industrial purposes as the bridges and machines dampers, this trend of recycling doesn’t take a sufficient care comparing with the other uses. There are a lot of studies conducted in these field, these studies suggests many methods to manage the huge number of scrap tires, the current paper aims to use the old rubber tires in engineering purposes (especially as a coupler joins the motor or engines with the other equipment as electric dynamo or pumps, the study focusing on the mechanical properties of a strip from a used tires and comparing with one prepared in the lab., and suggesting a new method to use as an engineering parts (for example the coupler lays between the IC engine and the dynamo of an electric generator. One of the results obtained from the experiments, there is no significant difference between the mechanical properties of the old and the new strip, (in the tensile test, the breaking force of the -Lab. tensile specimen- is 137 N whereas the specimen of old tire have a breaking force 113.27 N, but they are same in the elongation. A computational example is suggested to estimate the dimensions of a flexible coupler use an old tire pieces.

  10. Laser phase and frequency noise measurement by Michelson interferometer composed of a 3 × 3 optical fiber coupler.

    Science.gov (United States)

    Xu, Dan; Yang, Fei; Chen, Dijun; Wei, Fang; Cai, Haiwen; Fang, Zujie; Qu, Ronghui

    2015-08-24

    A laser phase and frequency noise measurement method by an unbalanced Michelson interferometer composed of a 3 × 3 optical fiber coupler is proposed. The relations and differences of the power spectral density (PSD) of differential phase and frequency fluctuation, PSD of instantaneous phase and frequency fluctuation, phase noise and linewidth are derived strictly and discussed carefully. The method obtains the noise features of a narrow linewidth laser conveniently without any specific assumptions or noise models. The technique is also used to characterize the noise features of a narrow linewidth external-cavity semiconductor laser, which confirms the correction and robustness of the method.

  11. Multiplexing of adjacent vortex modes with the forked grating coupler

    Science.gov (United States)

    Nadovich, Christopher T.; Kosciolek, Derek J.; Crouse, David T.; Jemison, William D.

    2017-08-01

    For vortex fiber multiplexing to reach practical commercial viability, simple silicon photonic interfaces with vortex fiber will be required. These interfaces must support multiplexing. Toward this goal, an efficient singlefed multimode Forked Grating Coupler (FGC) for coupling two different optical vortex OAM charges to or from the TE0 and TE1 rectangular waveguide modes has been developed. A simple, apodized device implemented with e-beam lithography and a conventional dual-etch processing on SOI wafer exhibits low crosstalk and reasonable mode match. Advanced designs using this concept are expected to further improve performance.

  12. Integrated optical isolators based on two-mode interference couplers

    International Nuclear Information System (INIS)

    Sun, Yiling; Zhou, Haifeng; Jiang, Xiaoqing; Hao, Yinlei; Yang, Jianyi; Wang, Minghua

    2010-01-01

    This paper presents an optical waveguide isolator based on two-mode interference (TMI) couplers, by utilizing the magneto-optical nonreciprocal phase shift (NPS). The operating principle of this device is to utilize the difference between the nonreciprocal phase shifts of the two lowest-order modes. A two-dimensional (2D) semi-vectorial finite difference method is used to calculate the difference between the nonreciprocal phase shifts of the two lowest-order modes and optimize the parameters. The proposed device may play an important role in integrated optical devices and optical communication systems

  13. Design and characterization of dielectric-loaded plasmonic directional couplers

    DEFF Research Database (Denmark)

    Stær, Tobias Holmgaard; Chen, Zhuo; Bozhevolnyi, Sergey

    2009-01-01

    Ultracompact directional couplers (DCs) based on dielectric-loaded surface plasmon-polariton waveguides (DLSPPWs) are analyzed using the effective index method (EIM), with the coupling, both in the parallel interaction region and in- and out-coupling regions, being taken into account. Near-field...... characterization of fabricated DCs performed with a scanning near-field optical microscope verifies the applicability of the EIM in the analysis and design of DLSPPW-based wavelength-selective DCs. The design approach applicable to a large variety of integrated optical waveguides is developed, enabling...

  14. Near-field probing of photonic crystal directional couplers

    DEFF Research Database (Denmark)

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

    2006-01-01

    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....... 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....

  15. Investigation of in-vivo skin autofluorescence lifetimes under long-term cw optical excitation

    International Nuclear Information System (INIS)

    Lihachev, A; Ferulova, I; Vasiljeva, K; Spigulis, J

    2014-01-01

    The main results obtained during the last five years in the field of laser-excited in-vivo human skin photobleaching effects are presented. The main achievements and results obtained, as well as methods and experimental devices are briefly described. In addition, the impact of long-term 405-nm cw low-power laser excitation on the skin autofluorescence lifetime is experimentally investigated. (laser biophotonics)

  16. Study and development of an input coupler for the future TESLA collider

    International Nuclear Information System (INIS)

    Dupery, C.

    1996-01-01

    The TESLA (TeV Superconducting Linear Accelerator) is operating with a high frequency cavity resonator input coupler. Some technical restraints (such as thermal, mechanical, electrical, vacuum, multipactor discharge phenomena) constrain the development of this coupler. In order to solve these problems, studies have been performed at the French Atomic Energy Commission (CEA) and are presented in this paper

  17. 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....

  18. Enhancement of entanglement in the nonlinear optical coupler by homodyne-mediated feedback

    Energy Technology Data Exchange (ETDEWEB)

    Ke Shasha [Department of Physics, Huazhong Normal University, Wuhan 430079 (China); Cheng Guiping [Department of Physics, Huazhong Normal University, Wuhan 430079 (China); Zhang Lihui [Department of Physics, Jianghan University, Wuhan 430056 (China); Li, Gao-xiang [Department of Physics, Huazhong Normal University, Wuhan 430079 (China)

    2007-07-28

    The enhancement of the intracavity entanglement of a nonlinear coupler via homodyne-mediated quantum feedback is investigated. It is found that the feedback can effectively enhance the squeezing, entanglement and purity of a two-mode field in the nonlinear coupler by appropriately choosing the quadrature angle at which the quantum feedback is introduced.

  19. All-optical switching in lithium niobate directional couplers with cascaded nonlinearity

    NARCIS (Netherlands)

    Schiek, R.; Baek, Y.; Krijnen, Gijsbertus J.M.; Stegeman, G.I.; Baumann, I.; Sohler, W.

    1996-01-01

    We report on intensity-dependent switching in lithium niobate directional couplers. Large nonlinear phase shifts that are due to cascading detune the coupling between the coupler branches, which makes all-optical switching possible. Depending on the input intensity, the output could be switched

  20. Measurement of the surface-enhanced coherent anti-Stokes Raman scattering (SECARS) due to the 1574 cm(-1) surface-enhanced Raman scattering (SERS) mode of benzenethiol using low-power (CW diode lasers.

    Science.gov (United States)

    Aggarwal, Roshan L; Farrar, Lewis W; Greeneltch, Nathan G; Van Duyne, Richard P; Polla, Dennis L

    2013-02-01

    The surface-enhanced coherent anti-Stokes Raman scattering (SECARS) from a self-assembled monolayer (SAM) of benzenethiol on a silver-coated surface-enhanced Raman scattering (SERS) substrate has been measured for the 1574 cm(-1) SERS mode. A value of 9.6 ± 1.7×10(-14) W was determined for the resonant component of the SECARS signal using 17.8 mW of 784.9 nm pump laser power and 7.1 mW of 895.5 nm Stokes laser power; the pump and Stokes lasers were polarized parallel to each other but perpendicular to the grooves of the diffraction grating in the spectrometer. The measured value of resonant component of the SECARS signal is in agreement with the calculated value of 9.3×10(-14) W using the measured value of 8.7 ± 0.5 cm(-1) for the SERS linewidth Γ (full width at half-maximum) and the value of 5.7 ± 1.4×10(-7) for the product of the Raman cross section σSERS and the surface concentration Ns of the benzenethiol SAM. The xxxx component of the resonant part of the third-order nonlinear optical susceptibility |3 χxxxx((3)R)| for the 1574 cm(-1) SERS mode has been determined to be 4.3 ± 1.1×10(-5) cm·g(-1)·s(2). The SERS enhancement factor for the 1574 cm(-1) mode was determined to be 3.6 ± 0.9×10(7) using the value of 1.8×10(15) molecules/cm(2) for Ns.

  1. Cw and Q-switched Nd:NaLa(MoO4)2 laser noncritical to the temperature drift of the diode pump laser wavelength

    International Nuclear Information System (INIS)

    Ushakov, S N; Lis, Denis A; Subbotin, Kirill A; Romanyuk, V A; Shestakov, A V; Ryabochkina, P A; Shestakova, I A; Zharikov, Evgeny V

    2010-01-01

    Lasing in Nd:NaLa(MoO 4 ) 2 crystals is obtained without stabilisation of the diode pump wavelength. A dependence of the cw laser power (at a wavelength of 1059 nm) on the pump diode temperature is found within a range of 10-458C. It is shown that the variations in the diode temperature within this region change the lasing efficiency no more than by 30%. In the passive Q-switching regime, the experiments were performed under both pulsed and cw pumping. Upon pulsed pumping, the laser energy was 16 μJ at the output pulse duration of 11 ns. The laser wavelength was 1059 nm, as well as in the case of cw operation. Upon cw pumping with a power of 1.5 W, laser pulses were obtained with an energy of 15 μJ. (lasers)

  2. 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.

  3. High efficiency grating couplers based on shared process with CMOS MOSFETs

    International Nuclear Information System (INIS)

    Qiu Chao; Sheng Zhen; Wu Ai-Min; Wang Xi; Zou Shi-Chang; Gan Fu-Wan; Li Le; Albert Pang

    2013-01-01

    Grating couplers are widely investigated as coupling interfaces between silicon-on-insulator waveguides and optical fibers. In this work, a high-efficiency and complementary metal—oxide—semiconductor (CMOS) process compatible grating coupler is proposed. The poly-Si layer used as a gate in the CMOS metal—oxide—semiconductor field effect transistor (MOSFET) is combined with a normal fully etched grating coupler, which greatly enhances its coupling efficiency. With optimal structure parameters, a coupling efficiency can reach as high as ∼ 70% at a wavelength of 1550 nm as indicated by simulation. From the angle of fabrication, all masks and etching steps are shared between MOSFETs and grating couplers, thereby making the high performance grating couplers easily integrated with CMOS circuits. Fabrication errors such as alignment shift are also simulated, showing that the device is quite tolerant in fabrication. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  4. Initial operation of the CW 8X H- ion source discharge

    International Nuclear Information System (INIS)

    Smith, H.V. Jr.; Allison, P.; Geisik, C.; Schmitt, D.R.; Schneider, J.D.; Stelzer, J.E.

    1993-01-01

    A pulsed 8Χ source was built and the H - beam current, emittance, and power efficiency were measured. These results were promising, so a cooled, dc version designed for operation at arc power levels up to 30 kW was built. Testing of the CW 8Χ source discharge is underway. The design dc power loading on the cathode surface is 900 W/cm 2 , considerably higher than achieved in any pervious Penning surface-plasma source (SPS). Thus, the electrode surfaces are cooled with pressurized, hot water. We describe the source and present the initial operating experience and arc test results

  5. Flight, orientation, and homing abilities of honeybees following exposure to 2.45-GHz CW microwaves.

    Science.gov (United States)

    Gary, N E; Westerdahl, B B

    1981-01-01

    Foraging-experienced honeybees retained normal flight, orientation, and memory functions after 30 minutes' exposure to 2.45-GHz CW microwaves at power densities from 3 to 50 mW/cm2. These experiments were conducted at power densities approximating and exceeding those that would be present above receiving antennas of the proposed solar power satellite (SPS) energy transmission system and for a duration exceeding that which honeybees living outside a rectenna might be expected to spend within the rectenna on individual foraging trips. There was no evidence that airborne invertebrates would be significantly affected during transient passage through microwaves associated with SPS ground-based microwave receiving stations.

  6. First 200 kW CW operation of a 60 GHz gyrotron

    International Nuclear Information System (INIS)

    Jory, H.; Bier, R.; Evans, S.; Felch, K.; Fox, L.; Huey, H.; Shively, J.; Spang, S.

    1983-01-01

    The gyrotron is a microwave tube which employs the electron cyclotron maser interaction to produce high power output at millimeter wavelengths. It has important and growing applications for heating of plasmas in controlled thermonuclear fusion experiments. The Varian 60 GHz gyrotron has recently generated microwave power in excess of 200 kW during CW operation, wth excellent dynamic range and operating stability. This is the highest average power ever produced by a microwave tube in the millimeter wave region. A description of the gyrotron design and test results are presented

  7. Initial operation of the CW 8X H- ion source discharge

    International Nuclear Information System (INIS)

    Smith, H.V. Jr.; Allison, P.; Geisik, C.; Schmitt, D.R.; Schneider, J.D.; Stelzer, J.E.

    1993-01-01

    A pulsed 8X source was built and the H - beam current, emittance, and power efficiency were measured. These results were promising, so a cooled, dc version designed for operation at arc power levels up to 30 kW was built. Testing of the CW 8X source discharge is underway. The design dc power loading on the cathode surface is 900 W/cm 2 , considerably higher than achieved in any previous Penning surface-plasma source (SPS). Thus, the electrode surfaces are cooled with pressurized, hot water. The authors describe the source and present the initial operating experience and arc test results

  8. Model coupler for coupling of atmospheric, oceanic, and terrestrial models

    International Nuclear Information System (INIS)

    Nagai, Haruyasu; Kobayashi, Takuya; Tsuduki, Katsunori; Kim, Keyong-Ok

    2007-02-01

    A numerical simulation system SPEEDI-MP, which is applicable for various environmental studies, consists of dynamical models and material transport models for the atmospheric, terrestrial, and oceanic environments, meteorological and geographical databases for model inputs, and system utilities for file management, visualization, analysis, etc., using graphical user interfaces (GUIs). As a numerical simulation tool, a model coupling program (model coupler) has been developed. It controls parallel calculations of several models and data exchanges among them to realize the dynamical coupling of the models. It is applicable for any models with three-dimensional structured grid system, which is used by most environmental and hydrodynamic models. A coupled model system for water circulation has been constructed with atmosphere, ocean, wave, hydrology, and land-surface models using the model coupler. Performance tests of the coupled model system for water circulation were also carried out for the flood event at Saudi Arabia in January 2005 and the storm surge case by the hurricane KATRINA in August 2005. (author)

  9. Preventing distortion of quick couplers of hoses of central pipe lines--a cheap and simple method.

    Directory of Open Access Journals (Sweden)

    Kamath S

    1995-01-01

    Full Text Available A cheap and practical approach of steel chains attached to the station outlet quick couplers helps in maintaining the shape of the quick couplers and ensures their effective functioning over a long period of time and avoids mishap of connection due to damage of these couplers.

  10. Design of a 300 GHZ broadband coupler and RF-structure

    International Nuclear Information System (INIS)

    Krawczyk, F.L.; Carlsten, B.E.; Earley, L.M.; Sigler, F.E.; Potter, J.M.; Schulze, M.E.

    2004-01-01

    Recent LANL activities in millimeter wave structures focus on 95 and 300 GHz structures. They aim at power generation from low power (100W-2kW) with a round electron beam (120kV, 0.1-1.0 A) to high power (2-100 kW) with a sheet beam structure (120 kV, 20 A). Applications cover basic research, radar and secure communications and remote sensing of biological and chemical agents. In this presentation the design of a 300 GHz RF-structure with a broadband (> 6% bandwidth) power coupler is presented. The choice of two input/output waveguides, a special coupling region and the structure parameters are presented. As a benchmark also a scaled up version at 10 GHz was designed and measured. These results will also be presented. We are investigating planar micro-fabricated traveling-wave tube amplifiers as sources for the generation of millimeter waves from 95 to 300 GHz. While for low energy applications narrow structures with pencil beams are proposed, for high energy operation flat, thin sheet beams are required. For the latter vane-loaded rectangular waveguides that operate in a slow-wave mode matched to the velocity of the electron beam are especially well suited. The 300 GHz effort initially is limited to narrow structures for pencil beams. The main emphasis for this work are the study of fabrication issues and the understanding of features that allow a broadband operation (5-10% bandwidth).

  11. Controllable generation and manipulation of micro-bubbles in water with absorptive colloid particles by CW laser radiation

    DEFF Research Database (Denmark)

    Angelsky, O. V.; Bekshaev, A. Ya.; Maksimyak, P. P.

    2017-01-01

    Micrometer-sized vapor-gas bubbles are formed due to local heating of a water suspension containing absorptive pigment particles of 100 nm diameter. The heating is performed by CW near-infrared (980 nm) laser radiation with controllable power, focused into a 100 mu m spot within a 2 mm suspension...

  12. Interaction of cw CO2 laser radiation with plasma near-metallic substrate surface

    Science.gov (United States)

    Azharonok, V. V.; Astapchik, S. A.; Zabelin, Alexandre M.; Golubev, Vladimir S.; Golubev, V. S.; Grezev, A. N.; Filatov, Igor V.; Chubrik, N. I.; Shimanovich, V. D.

    2000-07-01

    Optical and spectroscopic methods were used in studying near-surface plasma that is formed under the effect CW CO2 laser of (2- 5)x106W/cm2 power density upon stainless steel in He and Ar shielding gases. The variation of plume spatial structure with time has been studied, the outflow of gas-vapor jets from the interaction area has been characterized. The spectra of plasma plume pulsations have been obtained for the frequency range Δf = 0-1 MHz. The temperature and electron concentration of plasma plume have been found under radiation effect upon the target of stainless steel. Consideration has been given to the most probable mechanisms of CW laser radiation-metal non-stationary interaction.

  13. Gain-switched CW fiber laser for improved supercontinuum generation in a PCF

    DEFF Research Database (Denmark)

    Larsen, Casper; Noordegraaf, Danny; Skovgaard, P.M.W.

    2011-01-01

    We demonstrate supercontinuum generation in a PCF pumped by a gain-switched high-power continuous wave (CW) fiber laser. The pulses generated by gain-switching have a peak power of more than 700 W, a duration around 200 ns, and a repetition rate of 200 kHz giving a high average power of almost 30 W....... By coupling such a pulse train into a commercial nonlinear photonic crystal fiber, a supercontinuum is generated with a spectrum spanning from 500 to 2250 nm, a total output power of 12 W, and an infrared flatness of 6 dB over a bandwidth of more than 1000 nm with a power density above 5 dBm/nm (3 m......W/nm). This is considerably broader than when operating the same system under CW conditions. The presented approach is attractive due to the high power, power scalability, and reduced system complexity compared to picosecond-pumped supercontinuum sources. © 2011 Optical Society of America....

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

    International Nuclear Information System (INIS)

    Wang Fang; Wang Erdong; Zhang Baocheng; 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-cell TESLA-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 TM 010 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. (authors)

  15. A replacement solvent for dimethylsulfoxide /DMSO/ in CW dye lasers

    Energy Technology Data Exchange (ETDEWEB)

    Herbelin, J.M.; McKay, J.A.

    1981-01-01

    The use of propylene glycol carbonate as a replacement solvent for dimethyl sulfoxide in a Coherent model 599-21 CW dye laser has been investigated. Up to 40 milliwatts of single frequency output was achieved at 875 nm.

  16. A Stepped Frequency CW SAR for Lightweight UAV Operation

    National Research Council Canada - National Science Library

    Morrison, Keith

    2005-01-01

    A stepped-frequency continuous wave (SF-CW) synthetic aperture radar (SAR), with frequency-agile waveforms and real-time intelligent signal processing algorithms, is proposed for operation from a lightweight UAV platform...

  17. Silicon nitride tri-layer vertical Y-junction and 3D couplers with arbitrary splitting ratio for photonic integrated circuits.

    Science.gov (United States)

    Shang, Kuanping; Pathak, Shibnath; Liu, Guangyao; Feng, Shaoqi; Li, Siwei; Lai, Weicheng; Yoo, S J B

    2017-05-01

    We designed and demonstrated a tri-layer Si3N4/SiO2 photonic integrated circuit capable of vertical interlayer coupling with arbitrary splitting ratios. Based on this multilayer photonic integrated circuit platform with each layer thicknesses of 150 nm, 50 nm, and 150 nm, we designed and simulated the vertical Y-junctions and 3D couplers with arbitrary power splitting ratios between 1:10 and 10:1 and with negligible(< -50 dB) reflection. Based on the design, we fabricated and demonstrated tri-layer vertical Y-junctions with the splitting ratios of 1:1 and 3:2 with excess optical losses of 0.230 dB. Further, we fabricated and demonstrated the 1 × 3 3D couplers with the splitting ratio of 1:1:4 for symmetric structures and variable splitting ratio for asymmetric structures.

  18. 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...... of the coupler, while the low frequency behavior was determined by the properties of the microphone, electronic circuits and inadvertent leakages in the acoustical coupling. The requirement for the microphone and pr-amplifier was a low inherent noise level. The setup was used for collection of heart sounds...... range from 200-700 Hz. The capability of the sensor to record diastolic heart sound in the relevant frequency range indicates that the sensor is suitable for recording of coronary murmurs....

  19. Fiber-chip edge coupler with large mode size for silicon photonic wire waveguides.

    Science.gov (United States)

    Papes, Martin; Cheben, Pavel; Benedikovic, Daniel; Schmid, Jens H; Pond, James; Halir, Robert; Ortega-Moñux, Alejandro; Wangüemert-Pérez, Gonzalo; Ye, Winnie N; Xu, Dan-Xia; Janz, Siegfried; Dado, Milan; Vašinek, Vladimír

    2016-03-07

    Fiber-chip edge couplers are extensively used in integrated optics for coupling of light between planar waveguide circuits and optical fibers. In this work, we report on a new fiber-chip edge coupler concept with large mode size for silicon photonic wire waveguides. The coupler allows direct coupling with conventional cleaved optical fibers with large mode size while circumventing the need for lensed fibers. The coupler is designed for 220 nm silicon-on-insulator (SOI) platform. It exhibits an overall coupling efficiency exceeding 90%, as independently confirmed by 3D Finite-Difference Time-Domain (FDTD) and fully vectorial 3D Eigenmode Expansion (EME) calculations. We present two specific coupler designs, namely for a high numerical aperture single mode optical fiber with 6 µm mode field diameter (MFD) and a standard SMF-28 fiber with 10.4 µm MFD. An important advantage of our coupler concept is the ability to expand the mode at the chip edge without leading to high substrate leakage losses through buried oxide (BOX), which in our design is set to 3 µm. This remarkable feature is achieved by implementing in the SiO 2 upper cladding thin high-index Si 3 N 4 layers. The Si 3 N 4 layers increase the effective refractive index of the upper cladding near the facet. The index is controlled along the taper by subwavelength refractive index engineering to facilitate adiabatic mode transformation to the silicon wire waveguide while the Si-wire waveguide is inversely tapered along the coupler. The mode overlap optimization at the chip facet is carried out with a full vectorial mode solver. The mode transformation along the coupler is studied using 3D-FDTD simulations and with fully-vectorial 3D-EME calculations. The couplers are optimized for operating with transverse electric (TE) polarization and the operating wavelength is centered at 1.55 µm.

  20. Development of photonic-crystal-fiber-based optical coupler with a broad operating wavelength range of 800 nm

    International Nuclear Information System (INIS)

    Yoon, Min-Seok; Kwon, Oh-Jang; Kim, Hyun-Joo; Chu, Su-Ho; Kim, Gil-Hwan; Lee, Sang-Bae; Han, Young-Geun

    2010-01-01

    We developed a broadband optical coupler based on a photonic crystal fiber (PCF), which is very useful for applications to optical coherence tomography (OCT). The PCF-based coupler is fabricated by using a fused biconical tapering (FBT) method. The PCF has six hexagonally-stacked layers of air holes. The PCF-based coupler has a nearly-flat 50/50 coupling ratio in a broad bandwidth range of 800 nm, which is much wider than that previously reported for a PCF-based coupler and a singlemode-fiber-based coupler. The bandwidth and the bandedge wavelength of the broadband coupler are controlled by changing the elongation length. The fabricated broadband optical coupler has great potential for realizing a broadband interferogram with a high resolution in an OCT system.

  1. Diode-pumped cw Tm3+:YAlO3 laser

    International Nuclear Information System (INIS)

    Borodin, N I; Kryukov, P V; Shestakov, A V; Popov, A V; Ushakov, S N

    2005-01-01

    The output parameters of a Tm 3+ :YAlO 3 laser pumped by laser diodes in the spectral region 802-810 nm are studied. The output cw power exceeded 10 W for the total efficiency above 30%. The laser wavelength varies in the range from 1946 to 1985 nm and is determined by the pump power and resonator losses in this spectral region. The efficiency of cross relaxation process during the population of the 3 F 4 laser level is measured. (lasers)

  2. CW-laser induced microchannels in dye-polymethacrylic acid films

    OpenAIRE

    M.A. Camacho-López

    2007-01-01

    In this work we report on the formation of microchannels on dye-polymethacrylic acid films using a cw-laser. A focalized beam of a He-Ne laser (632.8 nm emission line) was used to form microchannels on the films. It was found that there exists a laser power density threshold for a pit formation that depends on the dye concentration. The dimensions of the laser-induced channels are dependent on the laser power density. Microchannel formation in the transparent polymethacrylic acid films was no...

  3. 2.5 MeV CW 4-vane RFQ accelerator design for BNCT applications

    Science.gov (United States)

    Zhu, Xiaowen; Wang, Hu; Lu, Yuanrong; Wang, Zhi; Zhu, Kun; Zou, Yubin; Guo, Zhiyu

    2018-03-01

    Boron Neutron Capture Therapy (BNCT) promises a bright future in cancer therapy for its highly selective destruction of cancer cells, using the 10B +n→7Li +4 He reaction. It offers a more satisfactory therapeutic effect than traditional methods for the treatment of malignant brain tumors, head and neck cancer, melanoma, liver cancer and so on. A CW 4-vane RFQ, operating at 162.5 MHz, provides acceleration of a 20 mA proton beam to 2.5 MeV, bombarding a liquid lithium target for neutron production with a soft neutron energy spectrum. The fast neutron yield is about 1.73×1013 n/s. We preliminarily develop and optimize a beam shaping assembly design for the 7Li(p, n)7Be reaction with a 2.5 MeV proton beam. The epithermal neutron flux simulated at the beam port will reach up to 1 . 575 ×109 n/s/cm2. The beam dynamics design, simulation and benchmark for 2.5 MeV BNCT RFQ have been performed with both ParmteqM (V3.05) and Toutatis, with a transmission efficiency higher than 99.6% at 20 mA. To ease the thermal management in the CW RFQ operation, we adopt a modest inter-vane voltage design (U = 65 kV), though this does increase the accelerator length (reaching 5.2 m). Using the well-developed 3D electromagnetic codes, CST MWS and ANSYS HFSS, we are able to deal with the complexity of the BNCT RFQ, taking the contribution of each component in the RF volume into consideration. This allows us to optimize the longitudinal field distribution in a full-length model. Also, the parametric modeling technique is of great benefit to extensive modifications and simulations. In addition, the resonant frequency tuning of this RFQ is studied, giving the tuning sensitivities of vane channel and wall channel as -16.3 kHz/°C and 12.4 kHz/°C, respectively. Finally, both the multipacting level of this RFQ and multipacting suppressing in the coaxial coupler are investigated.

  4. 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......Two fiber Raman probes are presented, one based on an optically-poled double-clad fiber and the second based on an optically-poled double-clad fiber coupler respectively. Optical poling of the core of the fiber allows for the generation of enough 532nm light to perform Raman spectroscopy...

  5. 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.

  6. High Power CW Superconducting Linacs for EURISOL and XADS

    CERN Document Server

    Biarrotte, J L

    2004-01-01

    A multi-MW superconducting proton linac is proposed as the baseline solution for the EURISOL and the XADS driver accelerators. In the EURISOL project, which studies the design of the next-generation European ISOL facility, it is used to produce both neutron-deficient and neutron-rich exotic nuclei far from the valley of stability. In the PDS-XADS project, which aims to the demonstration of the feasibility of an ADS system for nuclear waste transmutation, it is used to produce the neutron flux required by the associated sub-critical reactor. In this paper, we report the main results and conclusions reached within these preliminary design studies. A special emphasis is given on the on-going and future R&D to be done to accomplish the demonstration of the full technology.

  7. Spin states of reduced fullerenes (C60 and C120O) by CW and pulsed EPR

    International Nuclear Information System (INIS)

    Boas, J.F.; Drew, S.C.; Pilbrow, J.R.; Boyd, P.D.W.; Paul, P.; Reed, C.A.; Sun, D.

    2003-01-01

    Full text: The ESTN (Electron Spin Transient Nutation) EPR (Electron Paramagnetic Resonance) experiments reported at Wagga 2002 showed that the spin states of the reduced fullerenes C 120 O (2-), C 120 O (3-) and C 120 O (4-) were S = 1, S = 1/2 and S = 1 respectively. Further experiments using CW (Continuous Wave) EPR have confirmed the results of Paul et al. and have now shown that these states are the ground states of these anions. In the case of C 60 (3-), the recent CW and ESTN EPR experiments have shown that the electronic ground state of this anion is S = 1/2. The observation of ground states of low multiplicity for these anions is contrary to expectations based on MO calculations and the application of Hund's rules. A series of CW EPR experiments on C 60 (3-) have shown that some previous results may need to be re-interpreted. This arises from the delineation of the effects of microwave power, modulation amplitude and frequency, sample temperature and freezing rate on the EPR spectrum which is the combination of a broad line, attributed to C 60 (3-), and a 'spike' attributed to C 120 O impurities and other oxygen related species. Our results cast doubt on the existence of Jahn-Teller effects at low temperatures and of a low-lying spin quartet excited state

  8. Wavelength tunable CW red laser generated based on an intracavity-SFG composite cavity

    Science.gov (United States)

    Zhang, Z. N.; Bai, Y.; Lei, G. Z.; Bai, B.; Sun, Y. X.; Hu, M. X.; Wang, C.; Bai, J. T.

    2016-12-01

    We report a wavelength-tunable watt-level continuous wave (CW) red laser that uses a composite cavity based on an intracavity sum-frequency generation (SFG). The composite cavity is composed of a LD side-pumped Nd: GdVO4 p-polarized 1062.9 nm resonant cavity and a resonant optical parametric oscillator (SRO) of s-polarized signal light using a periodically poled crystal MgO: PPLN. Based on the temperature tuning from 30 °C to 200 °C, the CW red laser beams are obtained in a tunable waveband from 634.4 nm to 649.1 nm, corresponding to a tunable output waveband from 3278.0 nm to 2940.2 nm of the mid-infrared idler lights. The maximum CW output power of the red laser at 634.4 nm and the idler light at 3278.0 nm reach 3.03 W and 4.13 W under 30 °C, respectively.

  9. Demonstration of a High-Order Mode Input Coupler for a 220-GHz Confocal Gyrotron Traveling Wave Tube

    Science.gov (United States)

    Guan, Xiaotong; Fu, Wenjie; Yan, Yang

    2018-02-01

    A design of high-order mode input coupler for 220-GHz confocal gyrotron travelling wave tube is proposed, simulated, and demonstrated by experimental tests. This input coupler is designed to excite confocal TE 06 mode from rectangle waveguide TE 10 mode over a broadband frequency range. Simulation results predict that the optimized conversion loss is about 2.72 dB with a mode purity excess of 99%. Considering of the gyrotron interaction theory, an effective bandwidth of 5 GHz is obtained, in which the beam-wave coupling efficiency is higher than half of maximum. The field pattern under low power demonstrates that TE 06 mode is successfully excited in confocal waveguide at 220 GHz. Cold test results from the vector network analyzer perform good agreements with simulation results. Both simulation and experimental results illustrate that the reflection at input port S11 is sensitive to the perpendicular separation of two mirrors. It provides an engineering possibility for estimating the assembly precision.

  10. 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...... for transverse-magnetic and transverse-electric modes are ~0.36 dB and ~0.66 dB per connection, respectively....

  11. Fiber pigtailed thin wall capillary coupler for excitation of microsphere WGM resonator.

    Science.gov (United States)

    Wang, Hanzheng; Lan, Xinwei; Huang, Jie; Yuan, Lei; Kim, Cheol-Woon; Xiao, Hai

    2013-07-01

    In this paper, we demonstrate a fiber pigtailed thin wall capillary coupler for excitation of Whispering Gallery Modes (WGMs) of microsphere resonators. The coupler is made by fusion-splicing an optical fiber with a capillary tube and consequently etching the capillary wall to a thickness of a few microns. Light is coupled through the peripheral contact between inserted microsphere and the etched capillary wall. The coupling efficiency as a function of the wall thickness was studied experimentally. WGM resonance with a Q-factor of 1.14 × 10(4) was observed using a borosilicate glass microsphere with a diameter of 71 μm. The coupler operates in the reflection mode and provides a robust mechanical support to the microsphere resonator. It is expected that the new coupler may find broad applications in sensors, optical filters and lasers.

  12. Large-Area Binary Blazed Grating Coupler between Nanophotonic Waveguide and LED

    Directory of Open Access Journals (Sweden)

    Hongqiang Li

    2014-01-01

    Full Text Available A large-area binary blazed grating coupler for the arrayed waveguide grating (AWG demodulation integrated microsystem on silicon-on-insulator (SOI was designed for the first time. Through the coupler, light can be coupled into the SOI waveguide from the InP-based C-band LED for the AWG demodulation integrated microsystem to function. Both the length and width of the grating coupler are 360 μm, as large as the InP-based C-band LED light emitting area in the system. The coupler was designed and optimized based on the finite difference time domain method. When the incident angle of the light source is 0°, the coupling efficiency of the binary blazed grating is 40.92%, and the 3 dB bandwidth is 72 nm at a wavelength of 1550 nm.

  13. CW and pulsed operation of a diode-end-pumped Tm:GdVO4 laser at room temperature

    International Nuclear Information System (INIS)

    Wang, Z G; Song, C W; Li, Y F; Ju, Y L; Wang, Y Z

    2009-01-01

    A room-temperature diode-end-pumped acousto-optical (AO) Q-switched Tm:GdVO 4 laser was firstly reported. The minimum AO Q-switch pulse width was measured to be about 48 ns with output power of 2 W and repetition rate of 5 kHz. Continuous-wave output power of 2.8 W at 1912 nm was obtained under the absorbed pump power of 15 W. In addition, laser pulse widths and the ratio of QCW power/CW power at different repetition rates were discussed

  14. Venous coupler use for free-flap breast reconstructions: specific analyses of TMG and DIEP flaps.

    Science.gov (United States)

    Bodin, Frédéric; Brunetti, Stefania; Dissaux, Caroline; Erik, A Sauleau; Facca, Sybille; Bruant-Rodier, Catherine; Liverneaux, Philippe

    2015-05-01

    The purpose of this report was to present the results of comparisons of anastomotic data and flap complications in the use of venous coupler in breast reconstruction with the transverse musculocutaneous gracilis (TMG) flap and the deep inferior epigastric perforator (DIEP) flap. Over a three-year period, 95 patients suffering from breast cancer were treated with mastectomy and breast reconstruction using free flaps. We performed 121 mechanical venous anastomoses for 105 flap procedures (80 DIEP and 25 TMG). The coupler size, anastomotic duration, number of anastomoses and postoperative complications were assessed for the entire series. The coupling device was perfectly suitable for all end-to-end anastomoses between the vein(s) of the flap and the internal mammary vein(s). No venous thrombosis occurred. The mean anastomotic time did not significantly differ between the DIEP (330 seconds) and TMG flap procedures (352 seconds) (P = 0.069). Additionally, there were no differences in coupling time observed following a comparison of seven coupler sizes (P = 0.066). The mean coupler size used during the TMG flap procedure was smaller than that used with the DIEP (2.4 mm versus 2.8 mm) (P TMG flap (28%) than with the DIEP flap (11%). The coupler size used was smaller for the TMG procedure and when double venous anastomosis was performed. Additionally, anastomotic time was not affected by the flap type or coupler size used or by anastomosis number. © 2014 Wiley Periodicals, Inc.

  15. Analysis of the rectangular resonator with butterfly MMI coupler using SOI

    Science.gov (United States)

    Kim, Sun-Ho; Park, Jun-Hee; Kim, Eudum; Jeon, Su-Jin; Kim, Ji-Hoon; Choi, Young-Wan

    2018-02-01

    We propose a rectangular resonator sensor structure with butterfly MMI coupler using SOI. It consists of the rectangular resonator, total internal reflection (TIR) mirror, and the butterfly MMI coupler. The rectangular resonator is expected to be used as bio and chemical sensors because of the advantages of using MMI coupler and the absence of bending loss unlike ring resonators. The butterfly MMI coupler can miniaturize the device compared to conventional MMI by using a linear butterfly shape instead of a square in the MMI part. The width, height, and slab height of the rib type waveguide are designed to be 1.5 μm, 1.5 μm, and 0.9 μm, respectively. This structure is designed as a single mode. When designing a TIR mirror, we considered the Goos-Hänchen shift and critical angle. We designed 3:1 MMI coupler because rectangular resonator has no bending loss. The width of MMI is designed to be 4.5 μm and we optimize the length of the butterfly MMI coupler using finite-difference time-domain (FDTD) method for higher Q-factor. It has the equal performance with conventional MMI even though the length is reduced by 1/3. As a result of the simulation, Qfactor of rectangular resonator can be obtained as 7381.

  16. Wakefield and RF Kicks Due to Coupler Asymmetry in TESLA-Type Accelerating Cavities

    International Nuclear Information System (INIS)

    Bane, K

    2008-01-01

    In a future linear collider, such as the International Linear Collider (ILC), trains of high current, low emittance bunches will be accelerated in a linac before colliding at the interaction point. Asymmetries in the accelerating cavities of the linac will generate fields that will kick the beam transversely and degrade the beam emittance and thus the collider performance. In the main linac of the ILC, which is filled with TESLA-type superconducting cavities, it is the fundamental (FM) and higher mode (HM) couplers that are asymmetric and thus the source of such kicks. The kicks are of two types: one, due to (the asymmetry in) the fundamental RF fields and the other, due to transverse wakefields that are generated by the beam even when it is on axis. In this report we calculate the strength of these kicks and estimate their effect on the ILC beam. The TESLA cavity comprises nine cells, one HM coupler in the upstream end, and one (identical, though rotated) HM coupler and one FM coupler in the downstream end (for their shapes and location see Figs. 1, 2) [1]. The cavity is 1.1 m long, the iris radius 35 mm, and the coupler beam pipe radius 39 mm. Note that the couplers reach closer to the axis than the irises, down to a distance of 30 mm

  17. Study of a CW, two-dimensional Thomson scattering diagnostic system

    International Nuclear Information System (INIS)

    Hsieh, C.L.; Bray, B.D.; Liu, C.

    2004-01-01

    We describe an approach to Thomson scattering diagnostic that relies upon a high power CW laser cavity and a rf signal detection technique, instead of the more usual pulsed high energy laser. The system has three major elements: an ultra long (∼150 m) laser resonance cavity that includes the plasma region; an array of CW diode lasers of high power and high modulation frequency that pumps and maintains the average cavity energy (∼10 mJ); and a lock-in detection system of narrow frequency bandwidth (∼2 kHz). The resonance cavity consists of a pumping chamber for power input from diode lasers, and many relay chambers (∼30) distributed across the plasma cross section for Thomson measurement. The cavity has a low energy loss (∼2% round trip) and zero output power. It is estimated that signal-to-noise of the system is ∼100 times better than the present pulsed system on DIII-D Tokamak due to the increase in usable laser energy and the improved background signal rejection

  18. Simulation and optimization of a polymer directional coupler electro-optic switch with push pull electrodes

    Science.gov (United States)

    Zheng, Chuan-Tao; Ma, Chun-Sheng; Yan, Xin; Wang, Xian-Yin; Zhang, Da-Ming

    2008-07-01

    Structural model and design technique are proposed for a polymer directional coupler electro-optic switch with rib waveguides and push-pull electrodes, of which the electric field distribution is analyzed by the conformal transforming method and image method. In order to get the minimum mode loss and the minimum switching voltage, the parameters of the waveguide and electrode are optimized, such as the core with, core thickness, buffer layer between the core and the electrode, coupling gap between the waveguides, electrode thickness, electrode width and electrode gap. Switching Characteristics are analyzed, which include the output power, insertion loss, and crosstalk. To realize normal switching function, the fabrication error, spectrum shift, and coupling loss between a single mode fiber (SMF) and the waveguide are discussed. Simulation results show that the coupling length is 3082 μm, push-pull switching voltage is 2.14 V, insertion loss is less than 1.17 dB, and crosstalk is less than -30 dB for the designed device.

  19. 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.

  20. Polymer waveguide couplers based on metal nanoparticle–polymer nanocomposites

    International Nuclear Information System (INIS)

    Signoretto, M; Suárez, I; Chirvony, V S; Martínez-Pastor, J; Abargues, R; Rodríguez-Cantó, P J

    2015-01-01

    In this work Au nanoparticles (AuNPs) are incorporated into poly(methyl methacrylate) (PMMA) waveguides to develop optical couplers that are compatible with planar organic polymer photonics. A method for growing AuNPs (of 10 to 100 nm in size) inside the commercially available Novolak resist is proposed with the intention of tuning the plasmon resonance and the absorption/scattering efficiencies inside the patterned structures. The refractive index of the MNP–Novolak nanocomposite (MNPs: noble metal nanoparticles) is carefully analysed both experimentally and numerically in order to find the appropriate fabrication conditions (filling factor and growth time) to optimize the scattering cross section at a desired wavelength. Then the nanocomposite is patterned inside a PMMA waveguide to exploit its scattering properties to couple and guide a normal incident laser light beam along the polymer. In this way, light coupling is experimentally demonstrated in a broad wavelength range (404–780 nm). Due to the elliptical shape of the MNPs the nanocomposite demonstrates a birefringence, which enhances the coupling to the TE mode up to efficiencies of around 1%. (paper)

  1. Effects of pressure rise on cw laser ablation of tissue

    Science.gov (United States)

    LeCarpentier, Gerald L.; Motamedi, Massoud; Welch, Ashley J.

    1991-06-01

    The objectives of this research were to identify mechanisms responsible for the initiation of continuous wave (cw) laser ablation of tissue and investigate the role of pressure in the ablation process. Porcine aorta samples were irradiated in a chamber pressurized from 1 X 10-4 to 12 atmospheres absolute pressure. Acrylic and Zn-Se windows in the experimental pressure chamber allowed video and infrared cameras to simultaneously record mechanical and thermal events associated with cw argon laser ablation of these samples. Video and thermal images of tissue slabs documented the explosive nature of cw laser ablation of soft biological media and revealed similar ablation threshold temperatures and ablation onset times under different environmental pressures; however, more violent initiation explosions with decreasing environmental pressures were observed. These results suggest that ablation initiates with thermal alterations in the mechanical strength of the tissue and proceeds with an explosion induced by the presence superheated liquid within the tissue.

  2. Circuits and systems for CW and pulsed high-field electron spin resonance

    OpenAIRE

    David Robert, Bolton

    2006-01-01

    This thesis is concerned with the design and realisation of components for a new state of the art 94GHz Electron Spin Resonance (ESR) spectrometer capable of operating in both pulsed and CW modes. The complete spectrometer is designed to provide phase coherent 1kW peak power sub-nanosecond π/2 pulses having variable duration and repetition rate. The mm-wave response of a paramagnetic sample to these pulses is detected with a superheterodyne detector. Such a system would offer a step change in...

  3. Sequence Control System of 1-MW CW Klystron for the PEFP

    CERN Document Server

    Park, Byoung R; Chun Myung Hwan; Han Yeung Jin; Hyo Jeong Maeng; Kim Sung Chul; Yang Jae Seok; Yu In Ha

    2005-01-01

    Sequence control system of 1-MW CW klystron for the PEFP (Proton Engineering Frontier Project) has been developed in order to drive the 1-MW klystron amplifier. The system is able to control several power supplies and many environment conditions. The hardware of sequence control and the interlock system are based on the Allen-Bradley's SLC500 Program Logic Controller (PLC). Also the system can be controlled by a touch screen at local mode or Ethernet network with high level HMI at remote mode.

  4. Problems in the development of autonomous mobile laser systems based on a cw chemical DF laser

    International Nuclear Information System (INIS)

    Aleksandrov, B P; Bashkin, A S; Beznozdrev, V N; Parfen'ev, M V; Pirogov, N A; Semenov, S N

    2003-01-01

    The problems involved in designing autonomous mobile laser systems based on high-power cw chemical DF lasers, whose mass and size parameters would make it possible to install them on various vehicles, are discussed. The need for mobility of such lasers necessitates special attention to be paid to the quest for ways and means of reducing the mass and size of the main laser systems. The optimisation of the parameters of such lasers is studied for various methods of scaling their systems. A complex approach to analysis of the optical scheme of the laser system is developed. (special issue devoted to the 80th anniversary of academician n g basov's birth)

  5. Comparison of GSM Modulated and CW Radiofrequency Radiation on Cells

    International Nuclear Information System (INIS)

    Pavicic, I.; Marjanovic, A.M.; Trosic, I.

    2011-01-01

    The aim of our study was to evaluate and compare effect of global system of mobile (GSM) modulation and continuous wave (CW) radiofrequency radiation (RF) on proliferation ability and viability of V79 Chinese hamster lung cells. Previously prepared samples of cells in culture were exposed for 1, 2 and 3 hours both to 915 MHz GSM modulated and to 935 MHz CW RF field in gigahertz transversal electromagnetic mode cell (GTEM-cell). Electric field strength for cells exposed to GSM modulation was set at 10 V/m and for CW exposed cells was 8.2 V/m. Average specific absorption rate (SAR) was calculated to be for GSM 0.23 W/kg and for CW 0.12 W/kg. V79 samples were plated in concentration of 1x10 4 cells/mL. Cell proliferation was determined by cell counts for each hour of exposure during five post-exposure days. Trypan blue exclusion test was used to determine cell viability. In comparison to control cell samples, proliferation of GSM irradiated cells showed significant decrease after 3 hours of exposure on the second and third post-exposure day. CW exposed cell samples showed significant decrease after 3 hours of exposure on the third post-exposure day. Viability of GSM and CW exposed cells did not significantly differ from matched control cell samples. Both applied RF fields have shown similar effect on cell culture growth, and cell viability of V79 cell line. In addition, applied GSM modulated RF radiation demonstrate bigger influence on proliferation of cells. (author)

  6. High power RF systems for LEHIPA of ADS

    International Nuclear Information System (INIS)

    Pande, Manjiri; Shrotriya, Sandip; Sharma, Sonal; Rao, B.V.R.; Mishra, J.K.; Patel, Niranjan; Gupta, S.K.

    2011-01-01

    Worldwide accelerator driven sub-critical system (ADS) has generated a huge interest for various reasons. In India, as a part of accelerator driven sub-critical system (ADS) program, a normal conducting, low energy high intensity proton accelerator (LEHIPA) of energy 20 MeV and beam current of 30 mA is being developed in Bhabha Atomic Research Centre (BARC). LEHIPA comprises of Electron Cyclotron Resonance (ECR) ion source (50 KeV), Radio Frequency Quadrupole (RFQ) accelerator (3 MeV) and Drift tube Linac (DTL) 1 and 2 (10 MeV and 20 MeV respectively). As per the accelerator physics design, RFQ requires nearly 530 kW RF power while each of DTL need 900 kW. Each accelerating cavity will be driven by a one- megawatt (CW) klystron based high power RF (HPRF) system at 352.21 MHz. Three such RF systems will be developed. The RF system has been designed around five cavity klystron tube TH2089F (Thales make) capable of delivering 1 MW continuous wave power at 352.21 MHz. The klystron has a gain of 40 dB and efficiency around 62 %. Each of the RF system comprises of a low power solid state driver (∼ 100 W), klystron tube, harmonic filter, directional coupler, Y-junction circulator (AFT make), RF load and WR2300 wave guide based RF transmission line each of 1 MW capacity. It also includes other subsystems like bias supplies (high voltage (HV) and low voltage (LV)), HV interface system, interlock and protection circuits, dedicated low conductivity water-cooling, pulsing circuitry/mechanisms etc. WR 2300 based RF transmission line transmits and feeds the RE power from klystron source to respective accelerating cavity. This transmission line starts from second port of the circulator and consists of straight sections, full height to half height transition, magic Tee, termination load at the centre of magic tee, half height sections, directional couplers and RE windows. For X-ray shielding, klystron will be housed in a lead (3 mm) based shielded cage. This system set up has a

  7. Toward improved software security training using a cyber warfare opposing force (CW OPFOR): the knowledge base design

    Science.gov (United States)

    Stytz, Martin R.; Banks, Sheila B.

    2005-03-01

    "Train the way you will fight" has been a guiding principle for military training and has served the warfighter well as evidenced by numerous successful operations over the last decade. This need for realistic training for all combatants has been recognized and proven by the warfighter and continues to guide military training. However, to date, this key training principle has not been applied fully in the arena of cyberwarfare due to the lack of realistic, cost effective, reasonable, and formidable cyberwarfare opponents. Recent technological advances, improvements in the capability of computer-generated forces (CGFs) to emulate human behavior, and current results in research in information assurance and software protection, coupled with increasing dependence upon information superiority, indicate that the cyberbattlespace will be a key aspect of future conflict and that it is time to address the cyberwarfare training shortfall. To address the need for a cyberwarfare training and defensive testing capability, we propose research and development to yield a prototype computerized, semi-autonomous (SAF) red team capability. We term this capability the Cyber Warfare Opposing Force (CW OPFOR). There are several technologies that are now mature enough to enable, for the first time, the development of this powerful, effective, high fidelity CW OPFOR. These include improved knowledge about cyberwarfare attack and defense, improved techniques for assembling CGFs, improved techniques for capturing and expressing knowledge, software technologies that permit effective rapid prototyping to be effectively used on large projects, and the capability for effective hybrid reasoning systems. Our development approach for the CW OPFOR lays out several phases in order to address these requirements in an orderly manner and to enable us to test the capabilities of the CW OPFOR and exploit them as they are developed. We have completed the first phase of the research project, which

  8. Feasibility study of the EU home team on a 170 GHz 1 MW CW gyrotron for ECH on ITER

    International Nuclear Information System (INIS)

    Iatrou, C.T.; Kern, S.; Thumm, M.; Moebius, A.; Nickel, H.U.; Horajitra, P.; Wien, A.; Tran, T.M.; Bon Mardion, G.; Pain, M.; Tonon, G.

    1995-03-01

    The gyrotron system for ECH and burn control on ITER requires at least 50 MW of RF power at frequencies near 170 GHz operating in CW. To meet these requirements, high efficiency gyrotron tubes with ≥1 MW power output capability are necessary, as well as simple coupling to either a quasi-optical or waveguide transmission line. The paper reports the feasibility study on the design of an ITER-relevant gyrotron oscillator at 170 GHz, 1 MW CW employing a diode electron gun, an advanced internal quasi-optical converter, a cryogenically cooled single disk sapphire window, and a depressed potential collector. The operating mode selection and the cavity design is a compromise between many design constraints. (author) 18 figs., 6 tabs., 21 refs

  9. A 700 MHZ, 1 MW CW RF System for a FEL 100mA RF Photoinjector

    CERN Document Server

    Roybal, William; Reass, William; Rees, Daniel; Tallerico, Paul J; Torrez, Phillip A

    2005-01-01

    This paper describes a 700 MHz, 1 Megawatt CW, high efficiency klystron RF system utilized for a Free Electron Laser (FEL) high-brightness electron photoinjector (PI). The E2V klystron is mod-anode tube that operates with a beam voltage of 95 kV. This tube, operating with a 65% efficiency, requires ~96 watts of input power to produce in excess of 1 MW of output power. This output drives the 3rd cell of a 2½-cell, p-mode PI cavity through a pair of planar waveguide windows. Coupling is via a ridge-loaded tapered waveguide section and "dog-bone" iris. This paper will present the design of the RF, RF transport, coupling, and monitoring/protection systems that are required to support CW operations of the 100 mA cesiated, semi-porous SiC photoinjector.

  10. Current-drive on the Versator-II tokamak with a slotted-waveguide fast-wave coupler

    International Nuclear Information System (INIS)

    Colborn, J.A.

    1987-11-01

    A slotted-waveguide fast-wave coupler has been constructed, without dielectric, and used to drive current on the Versator-II tokamak. Up to 35 kW of net microwave power at 2.45 GHz has been radiated into plasmas with 2 x 10 12 cm -3 ≤ mean of n/sub e/ ≤ 1.2 x 10 13 cm -3 and B/sub tor/ ≅ 1.0 T. The launched spectrum had a peak near N/sub parallel/ = -2.0 and a larger peak near N/sub parallel/ = 0.7. Radiating efficiency of the antenna was roughly independent of antenna position except when the antenna was at least 0.2 cm outside the limiter, in which case the radiating efficiency slightly improved as the antenna was moved farther outside. When the coupler was inside the limiter, radiating efficiency improved moderately with increased mean of n/sub e/. Current-drive efficiency was comparable to that of the slow wave and was not affected when the antenna spectrum was reversed; however, no current was driven for mean of n/sub e/ ≤ 2 x 10 12 cm -3 . These results indicate the fast wave was launched, but a substantial part of the power may have been mode-converted to the slow wave, possibly via a downshift in N/sub parallel/, and these slow waves may have been responsible for most of the driven current. Relevant theory for waves in plasma, current-drive efficiency, and coupling of the slotted-waveguide is discussed, the antenna design method is explained, and future work, including the construction of a much-improved probe-fed antenna, is described. 42 refs., 45 figs

  11. Design of an RF window for L-band CW klystron based on thermal-stress analysis

    International Nuclear Information System (INIS)

    Yamaguchi, Seiya; Sato, Isamu; Konashi, Kenji; Ohshika, Junji.

    1993-01-01

    Design of klystron RF window has been performed based on a thermal-stress analysis for L-band CW electron linac for nuclear wastes transmutation. It was shown that the hoop stress for a modified disk is 46% of that of normal disk. Thermal load test has been done which indicated that the modified disk is proof against power twice as much as that for the normal disk. (author)

  12. Processing Interband Cascade Laser for High Temperature CW Operation

    National Research Council Canada - National Science Library

    Tober, Richard

    2004-01-01

    A narrow ridge-waveguide mid-IR interband cascade laser based on Type-II InAs/GaInSh heterostructures processed with a thick gold heat spreading layer operated CW at temperatures ranging from 80 K to 214.4 K...

  13. CW-FIT: Group Contingency Effects across the Day

    Science.gov (United States)

    Wills, Howard P.; Iwaszuk, Wendy M.; Kamps, Debra; Shumate, Emily

    2014-01-01

    This study explored the effects of a group-contingency intervention on student behavior across academic instructional periods. Research suggests group contingencies are evidence-based practices, yet calls for investigation to determine the best conditions and groups suited for this type of intervention. CW-FIT (Class-Wide Function-related…

  14. Applications of KHZ-CW Lidar in Ecological Entomology

    Science.gov (United States)

    Malmqvist, Elin; Brydegaard, Mikkel

    2016-06-01

    The benefits of kHz lidar in ecological entomology are explained. Results from kHz-measurements on insects, carried out with a CW-lidar system, employing the Scheimpflug principle to obtain range resolution, are presented. A method to extract insect events and analyze the large amount of lidar data is also described.

  15. Quantum mechanical features of optically pumped CW FIR lasers

    Science.gov (United States)

    Seligson, D.; Leite, J. R. R.; Sanchez, A.; Feld, M. S.; Ducloy, M.

    1977-01-01

    Quantum mechanical predictions for the gain of an optically pumped CW FIR laser are presented for cases in which one or both of the pump and FIR transitions are pressure or Doppler broadened. The results are compared to those based on the rate equation model. Some of the quantum mechanical predictions are verified in CH3OH.

  16. Gain measurements in CO2 CW low pressure lasers

    International Nuclear Information System (INIS)

    Rodrigues, N.A.S.; Chanes Junior, J.B.; Jayaram, K.

    1983-01-01

    A series of gain measurements in low pressure CO 2 CW laser were performed in order to study the behaviour of a CO 2 laser ampliflier as a function of pressure and discharge current. A theoretical model, based on rate equations is also presented to describe the laser behaviour and the experimental procedure adopted. (C.L.B.) [pt

  17. A study of polaritonic transparency in couplers made from excitonic materials

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Mahi R.; Racknor, Chris [Department of Physics and Astronomy, Western University, London, Ontario N6A 3K7 (Canada)

    2015-03-14

    We have studied light matter interaction in quantum dot and exciton-polaritonic coupler hybrid systems. The coupler is made by embedding two slabs of an excitonic material (CdS) into a host excitonic material (ZnO). An ensemble of non-interacting quantum dots is doped in the coupler. The bound exciton polariton states are calculated in the coupler using the transfer matrix method in the presence of the coupling between the external light (photons) and excitons. These bound exciton-polaritons interact with the excitons present in the quantum dots and the coupler is acting as a reservoir. The Schrödinger equation method has been used to calculate the absorption coefficient in quantum dots. It is found that when the distance between two slabs (CdS) is greater than decay length of evanescent waves the absorption spectrum has two peaks and one minimum. The minimum corresponds to a transparent state in the system. However, when the distance between the slabs is smaller than the decay length of evanescent waves, the absorption spectra has three peaks and two transparent states. In other words, one transparent state can be switched to two transparent states when the distance between the two layers is modified. This could be achieved by applying stress and strain fields. It is also found that transparent states can be switched on and off by applying an external control laser field.

  18. 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.

  19. Geometric optimisation of an accurate cosine correcting optic fibre coupler for solar spectral measurement

    Science.gov (United States)

    Cahuantzi, Roberto; Buckley, Alastair

    2017-09-01

    Making accurate and reliable measurements of solar irradiance is important for understanding performance in the photovoltaic energy sector. In this paper, we present design details and performance of a number of fibre optic couplers for use in irradiance measurement systems employing remote light sensors applicable for either spectrally resolved or broadband measurement. The angular and spectral characteristics of different coupler designs are characterised and compared with existing state-of-the-art commercial technology. The new coupler designs are fabricated from polytetrafluorethylene (PTFE) rods and operate through forward scattering of incident sunlight on the front surfaces of the structure into an optic fibre located in a cavity to the rear of the structure. The PTFE couplers exhibit up to 4.8% variation in scattered transmission intensity between 425 nm and 700 nm and show minimal specular reflection, making the designs accurate and reliable over the visible region. Through careful geometric optimization near perfect cosine dependence on the angular response of the coupler can be achieved. The PTFE designs represent a significant improvement over the state of the art with less than 0.01% error compared with ideal cosine response for angles of incidence up to 50°.

  20. Geometric optimisation of an accurate cosine correcting optic fibre coupler for solar spectral measurement.

    Science.gov (United States)

    Cahuantzi, Roberto; Buckley, Alastair

    2017-09-01

    Making accurate and reliable measurements of solar irradiance is important for understanding performance in the photovoltaic energy sector. In this paper, we present design details and performance of a number of fibre optic couplers for use in irradiance measurement systems employing remote light sensors applicable for either spectrally resolved or broadband measurement. The angular and spectral characteristics of different coupler designs are characterised and compared with existing state-of-the-art commercial technology. The new coupler designs are fabricated from polytetrafluorethylene (PTFE) rods and operate through forward scattering of incident sunlight on the front surfaces of the structure into an optic fibre located in a cavity to the rear of the structure. The PTFE couplers exhibit up to 4.8% variation in scattered transmission intensity between 425 nm and 700 nm and show minimal specular reflection, making the designs accurate and reliable over the visible region. Through careful geometric optimization near perfect cosine dependence on the angular response of the coupler can be achieved. The PTFE designs represent a significant improvement over the state of the art with less than 0.01% error compared with ideal cosine response for angles of incidence up to 50°.

  1. Multimode quantum model of a cw atom laser

    International Nuclear Information System (INIS)

    Hope, J.J.; Haine, S.A.; Savage, C.M.

    2002-01-01

    Full text: Laser cooling allows dilute atomic gases to be cooled to within K of absolute zero. Ultracold gases were first achieved twenty years ago and have since found applications in areas such as spectroscopy, time standards, frequency standards, quantum information processing and atom optics. The atomic analogue of the lasing mode in optical lasers is Bose-Einstein Condensation (BEC), in which a cooled sample of atoms condense into the lowest energy quantum state. This new state of matter was recently achieved in dilute Bose gases in 1995. Atoms coupled out of a BEC exhibit long-range spatial coherence, and provide the coldest atomic source currently available. These atomic sources are called 'atom lasers' because the BEC is analogous to the lasing mode of an optical laser. The high spectral flux from optical lasers is caused by a process called gain-narrowing, which requires continuous wave (cw) operation. Coupling a BEC quickly into an untrapped state forms a coherent atomic beam but it has a spread in momentum as large as the trapped BEC. Coupling the atoms out more slowly reduces the output linewidth at the expense of reducing the overall flux. These atom lasers are equivalent to Q-switched optical lasers. A cw atom laser with gain-narrowing would produce an increasingly monoenergetic output as the flux increased, dramatically improving the spectral flux. A cw atom laser is therefore a major goal of the atom optics community, but there are several theoretical and practical obstacles to understanding the complexities of such a system. The main obstacle to the production of a cw atom laser is the technical difficulties involved in continuously pumping the lasing mode. No complete theory exists which describes a cw atom laser. Complete cw atom laser models require a quantum field description due to their non-Markovian dynamics, significant spatial effects and the dependence of the output on the quantum statistics of the lasing mode. The extreme dimensionality

  2. 1-kilowatt CW all-fiber laser oscillator pumped with wavelength-beam-combined diode stacks.

    Science.gov (United States)

    Xiao, Y; Brunet, F; Kanskar, M; Faucher, M; Wetter, A; Holehouse, N

    2012-01-30

    We have demonstrated a monolithic cladding-pumped ytterbium-doped single all-fiber laser oscillator generating 1 kW of CW signal power at 1080 nm with 71% slope efficiency and near diffraction-limited beam quality. Fiber components were highly integrated on "spliceless" passive fibers to promote laser efficiency and alleviate non-linear effects. The laser was pumped through a 7:1 pump combiner with seven 200-W 91x nm fiber-pigtailed wavelength-beam-combined diode-stack modules. The signal power of such a single all-fiber laser oscillator showed no evidence of roll-over, and the highest output was limited only by available pump power.

  3. 1 MW, 352.2 MHz, CW and Pulsed RF test stand

    International Nuclear Information System (INIS)

    Badapanda, M.K.; Tripathi, Akhilesh; Upadhyay, Rinki; Tyagi, Rajiv; Hannurkar, P.R.

    2011-01-01

    A 1 MW, 352.2 MHz, RF test stand based on Thales make TH 2089 klystron amplifier is being developed at Raja Ramanna Centre for Advanced Technology (RRCAT), Indore for characterization and qualification of RF components, cavities and related subsystems. Provision to vary RF power from 50 kW to 1 MW with adequate flexibility for testing wide range of HV components, RF components and cavities is incorporated in this test stand. The paper presents a brief detail of various power supplies like high voltage cathode bias power supply, modulating anode power supply, filament power supply, electromagnet power supplies and ion pump power supplies along with their interconnections for biasing TH 2089 klystron amplifier. A digital control and interlock system is being developed to realize proper sequence of operation of various power supplies and to monitor the status of crucial parameters in this test set up. This RF test stand will be a unique national facility, capable of providing both CW and pulse RF power for realizing reliable RF power sources for various projects including the development of high energy proton linac under ADSS program of the Department of Atomic Energy. (author)

  4. Efficient third harmonic generation of a CW-fibered 1.5 µm laser diode

    Science.gov (United States)

    Philippe, Charles; Chea, Erick; Nishida, Yoshiki; du Burck, Frédéric; Acef, Ouali

    2016-10-01

    We report on frequency tripling of CW-Telecom laser diode using two cascaded PPLN ridge nonlinear crystals, both used in single-pass configuration. All optical components used for this development are fibered, leading to a very compact and easy to use optical setup. We have generated up to 290 mW optical power in the green range, from 800 mW only of infrared power around 1.54 µm. This result corresponds to an optical conversion efficiency P 3 ω / P ω > 36 %. To our knowledge, this is best value ever demonstrated up today for a CW-third harmonic generation in single-pass configuration. This frequency tripling experimental setup was tested over more than 2 years of continuous operation, without any interruption. The compactness and the reliability of our device make it very suitable as a transportable optical oscillator. In particular, it paves the way for embedded applications thanks to the high level of long-term stability of the optical alignments.

  5. Optimization of the microwave coupler and microwave measurements of the microtron cavity for 20 MeV pre-injector microtron for INDUS-I SRS

    International Nuclear Information System (INIS)

    Wanmode, Y.D.; Shrivastava, Purushottam; Hannurkar, P.R.

    2003-01-01

    A 20 MeV microtron was developed indigenously by CAT for pre-injection of 20 MeV electrons to the 450 MeV/700 MeV Booster Synchrotron for INDUS-I and INDUS-II Synchrotron Radiation Sources. The injector microtron uses a high Q microwave cavity for acceleration of electrons. The microwave power is fed to the microtron cavity through an iris type coupler whose dimensions are optimized for the coupling factor and resonant frequency for the accelerator. The present paper gives the procedure details for coupling factor optimization, tuning of the resonant frequency and results achieved. (author)

  6. CW Energy Recovery Operation of XFELs

    International Nuclear Information System (INIS)

    Jacek Sekutowicz; S. Bogacz; Dave Douglas; Peter Kneisel; Gwyn P. Wiliams; Massimo Ferrario; Luca Serafini; Ilan Ben-Zvi; James Rose; Triveni Srinivasan-Rao; Patrick Colestock; Wolf-Dietrich Moeller; Bernd Petersen; Dieter Proch; S. Simrock; James B. Rosenzweig

    2003-01-01

    Commissioning of two large coherent light facilities at SLAC and DESY should begin in 2008 and in 2011 respectively. In this paper we look further into the future, hoping to answer, in a very preliminary way, two questions. First: What will the next generation of the XFEL facilities look like ? Believing that super-conducting technology offers several advantages over room-temperature technology, such as high quality beams with highly populated bunches and the possibility of energy recovery or higher overall efficiency, we focus this preliminary study on the superconducting option. From this belief the second question arises: ''What modifications in superconducting technology and in machine design are needed, as compared to the present DESY XFEL, and what kind of R and D program is required over the next few years to arrive at a technically feasible solution with even higher brilliance and increased overall conversion of AC power to photon beam power. In this paper we will very often refer to and profit from the DESY XFEL design, acknowledging its many technically innovative solutions

  7. Contribution to the study of accelerating structure for electrons and respective radiofrequency couplers

    International Nuclear Information System (INIS)

    Franco, M.A.R.

    1991-01-01

    In this work, the experimental results pertaining to the construction and evaluation of a constant gradient accelerating structure and of the radiofrequency couplers are presented. The theoretical methods to determine the initial dimensions of the iris-loaded accelerating structure are presented. The final dimensions have been experimentally determined utilizing four three-cavity sections representing the 4 sup(th), 12 sup(th), 20 sup(th) and 27 sup(th) cavities of the final structure. The diameters of the cavities were corrected for variations of temperature, pressure and humidity. A v sub(p) = c, constant gradient, twelve-cavity prototype of the accelerating structure have been constructed and its principal parameters were experimentally determined according to methods also described in this work. Two prototypes of door-knob type radiofrequency couplers have been constructed and experimental procedures to match and tune the couplers and the accelerating structure were implemented. (author)

  8. Proton damage in linear and digital opto-couplers; Effets des protons sur des optocoupleurs lineaires et numeriques

    Energy Technology Data Exchange (ETDEWEB)

    Johnston, A.; Rax, B.G. [California Institute of Technology, Jet Propulsion Laboratory, Pasadena (United States)

    1999-07-01

    This paper discusses proton degradation of linear and digital opto-couplers. One obvious way to harden opto-coupler technologies is to select LEDs (light emitting diodes) that are more resistant to displacement damage. A direct comparison is made of degradation of a commercial linear opto-coupler from one manufactured with a modified version of the same device with a different LED technology. Other factors, including degradation of optical photoresponse and transistor gain are also discussed, along with basic comparisons of digital and analog opto-couplers. The experimental work has been made with 50 MeV protons. 3 underlying factors contribute to opto-coupler degradation. The most important factor is LED degradation, it is possible to select opto-coupler with double-heterojunction LEDs that are inherently more resistant to displacement damage. The second factor is gain degradation that is particularly important for opto-couplers with sensitive LEDs because the light output decreases so much at low radiation levels. The third factor, optical photoresponse is the largest contribution to CTR (current transfer ratio) degradation for opto-couplers with improved LED hardness. Photoresponse degradation depends on wavelength because the absorption coefficient is wavelength dependent. (A.C.)

  9. Ultra-low coupling loss fully-etched apodized grating coupler with bonded metal mirror

    DEFF Research Database (Denmark)

    Ding, Yunhong; Peucheret, Christophe; Ou, Haiyan

    2014-01-01

    A fully etched apodized grating coupler with bonded metal mirror is designed and demonstrated on the silicon-on-insulator platform, showing an ultra-low coupling loss of only 1.25 dB with 3 dB bandwidth of 69 nm.......A fully etched apodized grating coupler with bonded metal mirror is designed and demonstrated on the silicon-on-insulator platform, showing an ultra-low coupling loss of only 1.25 dB with 3 dB bandwidth of 69 nm....

  10. Structural and dynamic analysis of an ultra short intracavity directional coupler

    Science.gov (United States)

    Gravé, Ilan; Griffel, Giora; Daou, Youssef; Golan, Gadi

    1997-01-01

    A recently proposed intracavity directional coupler is analysed. Exact analytic expressions for important parameters such as the transmission ratio, the coupling length, and the photon lifetime are given. We show that by controlling the mirror reflectivities of the cavity, it is theoretically possible to reduce the coupling length to a zero limit. The photon lifetime, which governs the dynamic properties of the structure, sets an upper frequency limit of a few hundreds of GHz, which is well over the bandwidth limitation of microwave lumped or travelling wave electrodes. This novel family of intracavity couplers has important applications in the realization of integrated optics circuits for high-speed computing, data processing, and communication.

  11. 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....

  12. Ultra-High-Efficiency Apodized Grating Coupler Using a Fully Etched Photonic Crystal

    DEFF Research Database (Denmark)

    Ding, Yunhong; Peucheret, Christophe; Ou, Haiyan

    2013-01-01

    We demonstrate an apodized fiber-to-chip grating coupler using fully etched photonic crystal holes on the silicon-on-insulator platform. An ultra-high coupling efficiency of 1.65 dB (68%) with 3 dB bandwidth of 60 nm is experimentally demonstrated.......We demonstrate an apodized fiber-to-chip grating coupler using fully etched photonic crystal holes on the silicon-on-insulator platform. An ultra-high coupling efficiency of 1.65 dB (68%) with 3 dB bandwidth of 60 nm is experimentally demonstrated....

  13. Microfabrication of pre-aligned fiber bundle couplers using ultraviolet lithography of SU-8

    OpenAIRE

    Yang, Ren; Soper, Steven A.; Wang, Wanjun

    2006-01-01

    This paper describes the design, microfabrication and testing of a pre-aligned array of fiber couplers using direct UV-lithography of SU-8. The fiber coupler array includes an out-of-plane refractive microlens array and two fiberport collimator arrays. With the optical axis of the pixels parallel to the substrate, each pixel of the microlens array can be pre-aligned with the corresponding pixels of the fiberport collimator array as defined by the lithography mask design. This out-of-plane pol...

  14. Multi-layered dielectric cladding plasmonic microdisk resonator filter and coupler

    International Nuclear Information System (INIS)

    Han Cheng, Bo; Lan, Yung-Chiang

    2013-01-01

    This work develops the plasmonic microdisk filter/coupler, whose effectiveness is evaluated by finite-difference time-domain simulation and theoretical analyses. Multi-layer dielectric cladding is used to prevent the scattering of surface plasmons (SPs) from a silver microdisk. This method allows devices that efficiently perform filter/coupler functions to be developed. The resonant conditions and the effective refractive index of bounded SP modes on the microdisk are determined herein. The waveguide-to-microdisk distance barely influences the resonant wavelength but it is inversely related to the bandwidth. These findings are consistent with predictions made using the typical ring resonator model.

  15. Characteristics of the evolution of a plasma generated by radiation from CW and repetitively pulsed CO2 lasers in different gases

    Science.gov (United States)

    Kanevskii, M. F.; Stepanova, M. A.

    1990-06-01

    The interaction between high-power CW and repetitively pulsed CO2 laser radiation and a low-threshold optical-breakdown plasma near a metal surface is investigated. The characteristics of the breakdown plasma are examined as functions of the experimental conditions. A qualitative analysis of the results obtained was performed using a simple one-dimensional model for laser combustion waves.

  16. Study of Physical Properties of SiCw/Al Composites During Unloaded Thermal Cycling

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xin-ming; TIAN zhi-gang; CHENG hua; ZHU Xiao-gang; CHEN Wen-li

    2004-01-01

    The thermal expansion coefficient of SiCw/Al composites squeeze cast during unloaded thermal cycling was determined and analyzed. The study had shown that the thermal expansion coefficient of SiCw/Al composites reduced greatly with temperature raising. The thermal expansion coefficient of artificial ageing treatment SiCw/Al composites during unloaded thermal cycling reduced gradually, while the thermal expansion coefficient of squeezing SiCw/Al composites increased gradually. In addition, the thermal expansion coefficient of SiCw/Al composites reduced drastically with fiber fraction increasing.

  17. Optical trapping assembling of clusters and nanoparticles in solution by CW and femtosecond lasers

    KAUST Repository

    Masuhara, Hiroshi

    2015-02-01

    Laser trapping of molecular systems in solution is classified into three cases: JUST TRAPPING, EXTENDED TRAPPING, and NUCLEATION and GROWTH. The nucleation in amino acid solutions depends on where the 1064-nm CW trapping laser is focused, and crystallization and liquid–liquid phase separation are induced by laser trapping at the solution/air surface and the solution/glass interface, respectively. Laser trapping crystallization is achieved even in unsaturated solution, on which unique controls of crystallization are made possible. Crystal size is arbitrarily controlled by tuning laser power for a plate-like anhydrous crystal of l-phenylalanine. The α- or γ-crystal polymorph of glycine is selectively prepared by changing laser power and polarization. Further efficient trapping of nanoparticles and their following ejection induced by femtosecond laser pulses are introduced as unique trapping phenomena and finally future perspective is presented.

  18. Optical trapping assembling of clusters and nanoparticles in solution by CW and femtosecond lasers

    KAUST Repository

    Masuhara, Hiroshi; Sugiyama, Teruki; Yuyama, Kenichi; Usman, Anwar

    2015-01-01

    Laser trapping of molecular systems in solution is classified into three cases: JUST TRAPPING, EXTENDED TRAPPING, and NUCLEATION and GROWTH. The nucleation in amino acid solutions depends on where the 1064-nm CW trapping laser is focused, and crystallization and liquid–liquid phase separation are induced by laser trapping at the solution/air surface and the solution/glass interface, respectively. Laser trapping crystallization is achieved even in unsaturated solution, on which unique controls of crystallization are made possible. Crystal size is arbitrarily controlled by tuning laser power for a plate-like anhydrous crystal of l-phenylalanine. The α- or γ-crystal polymorph of glycine is selectively prepared by changing laser power and polarization. Further efficient trapping of nanoparticles and their following ejection induced by femtosecond laser pulses are introduced as unique trapping phenomena and finally future perspective is presented.

  19. Thermo-mechanical design of a CW sweep plate emittance scanner

    International Nuclear Information System (INIS)

    Rathke, J.; Peacock, M.; Sredniawski, J.

    1996-01-01

    A sweep plate emittance scanner for use with high power, continuous wave (CW) beams has been designed, fabricated and commissioned at Northrop Grumman. The design is capable of scanning beams of up to 20 kW beam power with a spot diameter as small as 2 cm. The scanner pod is mounted on a ball screw driven linear bearing table that is driven through the beam by a stepper motor at velocities up to 30 cm/sec. This paper presents the thermo-mechanical analysis of the pod moving through a gaussian beam and the details of the mechanical design of the pod and motion system. Analyses to determine scanner cooling schemes and structural materials are presented. (author)

  20. CW EPR parameters reveal cytochrome P450 ligand binding modes.

    Science.gov (United States)

    Lockart, Molly M; Rodriguez, Carlo A; Atkins, William M; Bowman, Michael K

    2018-06-01

    Cytochrome P450 (CYP) monoxygenses utilize heme cofactors to catalyze oxidation reactions. They play a critical role in metabolism of many classes of drugs, are an attractive target for drug development, and mediate several prominent drug interactions. Many substrates and inhibitors alter the spin state of the ferric heme by displacing the heme's axial water ligand in the resting enzyme to yield a five-coordinate iron complex, or they replace the axial water to yield a nitrogen-ligated six-coordinate iron complex, which are traditionally assigned by UV-vis spectroscopy. However, crystal structures and recent pulsed electron paramagnetic resonance (EPR) studies find a few cases where molecules hydrogen bond to the axial water. The water-bridged drug-H 2 O-heme has UV-vis spectra similar to nitrogen-ligated, six-coordinate complexes, but are closer to "reverse type I" complexes described in older liteature. Here, pulsed and continuous wave (CW) EPR demonstrate that water-bridged complexes are remarkably common among a range of nitrogenous drugs or drug fragments that bind to CYP3A4 or CYP2C9. Principal component analysis reveals a distinct clustering of CW EPR spectral parameters for water-bridged complexes. CW EPR reveals heterogeneous mixtures of ligated states, including multiple directly-coordinated complexes and water-bridged complexes. These results suggest that water-bridged complexes are under-represented in CYP structural databases and can have energies similar to other ligation modes. The data indicates that water-bridged binding modes can be identified and distinguished from directly-coordinated binding by CW EPR. Copyright © 2018 Elsevier Inc. All rights reserved.

  1. Analysis of free electron laser performance utilizing the National Bureau of Standards' CW microtron

    International Nuclear Information System (INIS)

    Tang, C.M.; Sprangle, P.; Penner, S.; Maruyama, X.K.

    1987-01-01

    The National Bureau of Standards' (NBS) CW racetrack microtron (RTM) will be utilized as a driver for a free electron laser (FEL) oscillator. The NBS RTM possesses many exceptional properties of value for the FEL: i) CW operation, ii) energy from 20-185 MeV, iii) small energy spread and emittance, iv) excellent energy stability, and v) high average power. The 1-D FEL gain formula predicts that the FEL would oscillate at the fundamental approximately from 0.25 μm to 10 μm when up-grading the peak current to ≥ 2 A. In this paper, the authors present 3-D self-consistent numerical results including several realistic effects, such as emittance, betatron oscillations, diffraction and refraction. The results indicate that the design value of the transverse emittance is small enough that it does not degrade the FEL performance for intermediate to long wavelengths, and only slightly degrades the performance at the shortest wavelength under consideration. Due to the good emittance, the current density is high enough that focusing, or guiding, begins to manifest itself for wavelengths > 2.0 μm

  2. National CW GeV Electron Microtron laboratory

    International Nuclear Information System (INIS)

    1982-12-01

    Rising interest in the nuclear physics community in a CW GeV electron accelerator reflects the growing importance of high-resolution short-range nuclear physics to future advances in the field. To meet this need, Argonne National Laboratory proposes to build a CW GeV Electron Microtron (GEM) laboratory as a national user facility. The microtron accelerator has been chosen as the technology to generate the electron beams required for the research discussed because of the advantages of superior beam quality, low capital and operating costs and capability of furnishing beams of several energies and intensities simultaneously. A complete technical description of the conceptual design for a six-sided CW microtron (hexatron) is presented. The hexatron and three experimental areas will be housed in a well-shielded complex of existing buildings that provide all utilities and services required for an advanced accelerator and an active research program at a savings of $30 to 40 million. Beam lines have been designed to accommodate the transport of polarized beams to each area. The total capital cost of the facility will be $78.6 million and the annual budget for accelerator operations will be $12.1 million. Design and construction of the facility will require four and one half years. Staged construction with a 2 GeV phase costing $65.9 million is also discussed

  3. GeV C.W. electron microtron design report

    International Nuclear Information System (INIS)

    1982-05-01

    Rising interest in the nuclear physics community in a GeV C.W. electron accelerator reflects the growing importance of high-resolution short-range nuclear physics to future advances in the field. In this report major current problems are reviewed and the details of prospective measurements which could be made with a GeV C.W. electron facility are discussed, together with their impact on an understanding of nuclear forces and the structure of nuclear matter. The microtron accelerator has been chosen as the technology to generate the electron beams required for the research discussed because of the advantages of superior beam quality, low capital and operating cost and capability of furnishing beams of several energies and intensities simultaneously. A complete technical description of the conceptual design for a 2 GeV double-sided C.W. electron microtron is presented. The accelerator can furnish three beams with independently controlled energy and intensity. The maximum current per beam is 100 μamps. Although the precise objective for maximum beam energy is still a subject of debate, the design developed in this study provides the base technology for microtron accelerators at higher energies (2 to 6 GeV) using multi-sided geometries

  4. A Variable Energy CW Compact Accelerator for Ion Cancer Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Johnstone, Carol J. [Fermilab; Taylor, J. [Huddersfield U.; Edgecock, R. [Huddersfield U.; Schulte, R. [Loma Linda U.

    2016-03-10

    Cancer is the second-largest cause of death in the U.S. and approximately two-thirds of all cancer patients will receive radiation therapy with the majority of the radiation treatments performed using x-rays produced by electron linacs. Charged particle beam radiation therapy, both protons and light ions, however, offers advantageous physical-dose distributions over conventional photon radiotherapy, and, for particles heavier than protons, a significant biological advantage. Despite recognition of potential advantages, there is almost no research activity in this field in the U.S. due to the lack of clinical accelerator facilities offering light ion therapy in the States. In January, 2013, a joint DOE/NCI workshop was convened to address the challenges of light ion therapy [1], inviting more than 60 experts from diverse fields related to radiation therapy. This paper reports on the conclusions of the workshop, then translates the clinical requirements into accelerat or and beam-delivery technical specifications. A comparison of available or feasible accelerator technologies is compared, including a new concept for a compact, CW, and variable energy light ion accelerator currently under development. This new light ion accelerator is based on advances in nonscaling Fixed-Field Alternating gradient (FFAG) accelerator design. The new design concepts combine isochronous orbits with long (up to 4m) straight sections in a compact racetrack format allowing inner circulating orbits to be energy selected for low-loss, CW extraction, effectively eliminating the high-loss energy degrader in conventional CW cyclotron designs.

  5. 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.

  6. 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.

  7. 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....

  8. 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...

  9. 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

    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...

  10. Comparative simulation studies of multipacting in higher-order-mode couplers of superconducting rf cavities

    Directory of Open Access Journals (Sweden)

    Y. M. Li

    2014-02-01

    Full Text Available 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 >40  MV/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 accelerators based on superconducting radio frequency cavities. Frequency scaling of MP’s predicted in HOM couplers of the ILC, CEBAF upgrade, Spallation Neutron Source (SNS, and Free-Electron Laser in Hamburg (FLASH third harmonic cavity is given and found to be in good agreement with the analytical result based on the parallel plate model.

  11. Optical fiber couplers for spectrophotometry. Perspectives for in-situ on-line and remote measurements

    International Nuclear Information System (INIS)

    Boisde, G.; Linger, C.; Chevalier, G.; Perez, J.J.

    1983-01-01

    Optical fiber couplers have been developed specially for nuclear chemical spectrophotometric applications. Coupling devices are described for TELEPHOT industrial photometers and some commercial spectrophotometer, together with the probes and measurement cells employed. The value of optical multiplexing is mentioned. Non nuclear applications in medical analysis are also mentioned, together with the possibilities offered by these devices for uses other than spectrophotometry [fr

  12. Development program for a 200 kW, CW, 28 GHz gyroklystron. Final report, April 1976-September 1980

    International Nuclear Information System (INIS)

    Shively, J.; Conner, C.; Evans, S.

    1980-01-01

    The objective of this program was to develop a microwave amplifier or oscillator capable of producing 200 kW, CW power output at 28 GHz. The use of the gyrotron or cyclotron resonance interaction was pursued. A room temperature hollow core solenoid magnet with an iron case was designed to produce the magnetic field required for electron cyclotron resonance. Three pulsed gyroklystron amplifiers were built providing increasing stable output powers of 6, 65 and 76 kW. A back-up pulsed gyrotron oscillator produced 248 kW. A ceramic cone broadband water load was developed. Tests are described for the various tubes that were developed

  13. Quasi-CW diode-pumped self-starting adaptive laser with self-Q-switched output.

    Science.gov (United States)

    Smith, G; Damzen, M J

    2007-05-14

    An investigation is made into a quasi-CW (QCW) diode-pumped holographic adaptive laser utilising an ultra high gain (approximately 10(4)) Nd:YVO(4) bounce amplifier. The laser produces pulses at 1064 nm with energy approximately 0.6 mJ, duration laser configuration, the output was amplified to obtain pulses of approximately 5.6 mJ energy, approximately 7 ns duration and approximately 1 MW peak power. The output spatial quality is also M(2)diode-pumped self-adaptive holographic lasers can provide a useful source of high peak power, short duration pulses with excellent spatial quality and narrow linewidth spectrum.

  14. All-solid-state quasi-CW yellow laser with intracavity self-Raman conversion and sum frequency generation

    International Nuclear Information System (INIS)

    Kananovich, A; Grabtchikov, A; Orlovich, V; Demidovich, A; Danailov, M

    2010-01-01

    Quasi continuous-wave (qCW) yellow emission (pulse duration 5 ms, repetition rate 20 Hz) at 559 nm is demonstrated through intracavity sum frequency generation (SFG) of Stokes and fundamental fields in Nd:YVO 4 diode pumped self-Raman laser for the first time. Average in pulse output power at 559 nm was 0.47 W for 22 W of pump power, which corresponds to 2.1% of diode-to-yellow efficiency. The pulsed mode of operation was due to diode pump modulation and was used to reduce thermal stress of the crystal

  15. Mounting power cables on SOLEIL

    CERN Multimedia

    Laurent Guiraud

    1999-01-01

    The power couplers are mounted on the SOLEIL cryomodule in a clean room. The cryomodule will allow superconducting technology to be used at SOLEIL, the French national synchrotron facility. This work is carried out as part of a collaboration between CERN and CEA Saclay, the French National Atomic Energy Commission.

  16. High-resolution smile measurement and control of wavelength-locked QCW and CW laser diode bars

    Science.gov (United States)

    Rosenkrantz, Etai; Yanson, Dan; Klumel, Genady; Blonder, Moshe; Rappaport, Noam; Peleg, Ophir

    2018-02-01

    High-power linewidth-narrowed applications of laser diode arrays demand high beam quality in the fast, or vertical, axis. This requires very high fast-axis collimation (FAC) quality with sub-mrad angular errors, especially where laser diode bars are wavelength-locked by a volume Bragg grating (VBG) to achieve high pumping efficiency in solid-state and fiber lasers. The micron-scale height deviation of emitters in a bar against the FAC lens causes the so-called smile effect with variable beam pointing errors and wavelength locking degradation. We report a bar smile imaging setup allowing FAC-free smile measurement in both QCW and CW modes. By Gaussian beam simulation, we establish optimum smile imaging conditions to obtain high resolution and accuracy with well-resolved emitter images. We then investigate the changes in the smile shape and magnitude under thermal stresses such as variable duty cycles in QCW mode and, ultimately, CW operation. Our smile measurement setup provides useful insights into the smile behavior and correlation between the bar collimation in QCW mode and operating conditions under CW pumping. With relaxed alignment tolerances afforded by our measurement setup, we can screen bars for smile compliance and potential VBG lockability prior to assembly, with benefits in both lower manufacturing costs and higher yield.

  17. Safety of panitumumab-IRDye800CW and cetuximab-IRDye800CW for fluorescence-guided surgical navigation in head and neck cancers.

    Science.gov (United States)

    Gao, Rebecca W; Teraphongphom, Nutte; de Boer, Esther; van den Berg, Nynke S; Divi, Vasu; Kaplan, Michael J; Oberhelman, Nicholas J; Hong, Steven S; Capes, Elissa; Colevas, A Dimitrios; Warram, Jason M; Rosenthal, Eben L

    2018-01-01

    Purpose: To demonstrate the safety and feasibility of leveraging therapeutic antibodies for surgical imaging. Procedures: We conducted two phase I trials for anti-epidermal growth factor receptor antibodies cetuximab-IRDye800CW (n=12) and panitumumab-IRDye800CW (n=15). Adults with biopsy-confirmed head and neck squamous cell carcinoma scheduled for standard-of-care surgery were eligible. For cetuximab-IRDye800CW, cohort 1 was intravenously infused with 2.5 mg/m 2 , cohort 2 received 25 mg/m 2 , and cohort 3 received 62.5 mg/m 2 . For panitumumab-IRDye800CW, cohorts received 0.06 mg/kg, 0.5 mg/kg, and 1 mg/kg, respectively. Electrocardiograms and blood samples were obtained, and patients were followed for 30 days post-study drug infusion. Results: Both fluorescently labeled antibodies had similar pharmacodynamic properties and minimal toxicities. Two infusion reactions occurred with cetuximab and none with panitumumab. There were no grade 2 or higher toxicities attributable to cetuximab-IRDye800CW or panitumumab-IRDye800CW; fifteen grade 1 adverse events occurred with cetuximab-IRDye800CW, and one grade 1 occurred with panitumumab-IRDye800CW. There were no significant differences in QTc prolongation between the two trials (p=0.8). Conclusions: Panitumumab-IRDye800CW and cetuximab-IRDye800CW have toxicity and pharmacodynamic profiles that match the parent compound, suggesting that other therapeutic antibodies may be repurposed as imaging agents with limited preclinical toxicology data.

  18. CW lasing of Ho in KLu(WO4)2 in-band pumped by a diode-pumped Tm:KLu(WO4)2 laser.

    Science.gov (United States)

    Mateos, Xavier; Jambunathan, Venkatesan; Pujol, Maria Cinta; Carvajal, Joan Josep; Díaz, Francesc; Aguiló, Magdalena; Griebner, Uwe; Petrov, Valentin

    2010-09-27

    We demonstrate continuous wave (CW) room temperature laser operation of the monoclinic Ho(3+)-doped KLu(WO(4))(2) crystal using a diode-pumped Tm(3+):KLu(WO(4))(2) laser for in-band pumping. The slope efficiency achieved amounts to ~55% with respect to the absorbed power and the maximum output power of 648 mW is generated at 2078 nm.

  19. cw argon laser annealing of anodic oxide on GaAs

    International Nuclear Information System (INIS)

    Chakravarti, S.N.; Das, P.; Webster, R.T.; Bhat, K.N.

    1981-01-01

    Anodic oxide films (850 +- 50 A thick) grown on n + (100) bulk GaAs were subjected to selective area annealing using a cw argon laser operating at an output power of 1.2 W. Capacitance-voltage (C-V) measurements performed on Al-anodic oxide-GaAs MOS capacitor structures show that laser-annealed capacitor dots have greatly reduced field-induced hysteresis effects in their capacitance-voltage characteristics compared to the unannealed ones. The oxide leakage current also shows a significant improvement: the leakage current magnitude of MOS capacitors in laser-annealed oxide island is over four orders of magnitude less than the oxide region which was not exposed to the laser radiation. Dielectric breakdown measurement indicates that laser-annealed capacitors have considerably higher breakdown voltages, about a factor of 2 higher than the unannealed capacitors

  20. Development of surgical CW Nd:YAG laser with optical fiber delivery system

    International Nuclear Information System (INIS)

    Kim, Cheol Jung; Kim, Jeong Mook; Jung, Chin Mann; Kim, Kwang Suk; Kim, Min Suk; Cho, Jae Wan; Kim, Duk Hyun

    1992-06-01

    We developed a surgical CW Nd:YAG laser with optical fiber delivery system. Several commercial models have been investigated in design and performance. We improved its quality to the level of commercial Nd:YAG laser by an endurance test for each parts of laser system. The maximum power of our surgical laser was 150 W and the laser pulse width could be controlled to 99 sec continuously by 0.1 sec. Many optical parts were localized and lowered much in cost. Only few parts were imported and almost 90% in cost were localized. Also, to find out the maintenance problem of this surgical laser, it was applicated to the production line of our joint company. (Author)

  1. Research on cw electron accelerators using room-temperature rf structures. Annual report

    International Nuclear Information System (INIS)

    1985-01-01

    Highlights reported include: measurement of the 100 keV chopped beam emittance, completion of installation of the entire 5 MeV injector linac system with all rf power and drive, extensive field mapping of one end magnet, completion of construction of the 12 MeV linac for the racetrack microtron (RTM), installation of most of the control system, and first acceleration of beam to 5 MeV. Plans for completion of the project are discussed. When the RTM is operating, it is expected to have many unique performance characteristics, including the cw nature of the beam, high current, easily variable energy over a wide range, excellent emittance, and small energy spread. Plans for future uses in the areas of nuclear physics, dosimetry research and standards, accelerator development, and free electron laser research are discussed. 19 refs

  2. Ceramic to metal joining by using 1064 nm pulsed and CW laser energy source

    International Nuclear Information System (INIS)

    Lee, Young Min; Kim, Soo Won; Choi, Hae Woon; Kim, Joo Han

    2013-01-01

    A novel joining method for ceramic and metallic layers is proposed using laser drilling and surface tension driven liquid metal filling. A high intensity laser beam irradiated a 500 µm thick ceramic filter, and the irradiated laser drilled the ceramic layer. The pulsed or CW laser transmitted through the ceramic layer irradiated the bottom metallic layer; the molten metallic layer then filled the drilled ceramic holes by the capillary force between the liquid metal and ceramic layer. As process variables, average laser power, pulse duration, and the number of pulses were used. The scattering optical properties were also studied for both green and red lasers. There was no significant difference between the colors and the estimated extinction coefficients were -26.94 1/mm and -28.42 1/mm for the green and red lasers, respectively.

  3. Operating experience and reliability improvements on the 5 kW CW klystron at Jefferson Lab

    International Nuclear Information System (INIS)

    Nelson, R.; Holben, S.

    1997-01-01

    With substantial operating hours on the RF system, considerable information on reliability of the 5 kW CW klystrons has been obtained. High early failure rates led to examination of the operating conditions and failure modes. Internal ceramic contamination caused premature failure of gun potting material and ultimate tube demise through arcing or ceramic fracture. A planned course of reporting and reconditioning of approximately 300 klystrons, plus careful attention to operating conditions and periodic analysis of operational data, has substantially reduced the failure rate. It is anticipated that implementation of planned supplemental monitoring systems for the klystrons will allow most catastrophic failures to be avoided. By predicting end of life, tubes can be changed out before they fail, thus minimizing unplanned downtime. Initial tests have also been conducted on this same klystron operated at higher voltages with resultant higher output power. The outcome of these tests will provide information to be considered for future upgrades to the accelerator

  4. Efficient Low-Voltage Operation of a CW Gyrotron Oscillator at 233 GHz.

    Science.gov (United States)

    Hornstein, Melissa K; Bajaj, Vikram S; Griffin, Robert G; Temkin, Richard J

    2007-02-01

    The gyrotron oscillator is a source of high average power millimeter-wave through terahertz radiation. In this paper, we report low beam power and high-efficiency operation of a tunable gyrotron oscillator at 233 GHz. The low-voltage operating mode provides a path to further miniaturization of the gyrotron through reduction in the size of the electron gun, power supply, collector, and cooling system, which will benefit industrial and scientific applications requiring portability. Detailed studies of low-voltage operation in the TE(2) (,) (3) (,) (1) mode reveal that the mode can be excited with less than 7 W of beam power at 3.5 kV. During CW operation with 3.5-kV beam voltage and 50-mA beam current, the gyrotron generates 12 W of RF power at 233.2 GHz. The EGUN electron optics code describes the low-voltage operation of the electron gun. Using gun-operating parameters derived from EGUN simulations, we show that a linear theory adequately predicts the low experimental starting currents.

  5. C-w operation of a 2-MeV RFQ accelerator

    International Nuclear Information System (INIS)

    Cornelius, W.D.

    1986-01-01

    We have achieved reliable cw operation of the Fusion Materials Irradiation Test (FMIT) radio-frequency quadrupole (RFQ) accelerator and have accelerated 40 mA of H 2 + beam to an energy of 2 MeV. The technical considerations for future cw accelerator designs, based on our experience in achieving cw operation, will be presented. Also to be discussed are measurements of beam emittance, matching into the RFQ, and beam transmission through the accelerator. These measurements will be compared with results of theoretical simulations of the device. The diagnostics instrumentation developed for characterizing intense cw beams also will be discussed, as well as the performance of those devices

  6. Fully etched apodized grating coupler on the SOI platform with −058 dB coupling efficiency

    DEFF Research Database (Denmark)

    Ding, Yunhong; Peucheret, Christophe; Ou, Haiyan

    2014-01-01

    We design and fabricate an ultrahigh coupling efficiency (CE) fully etched apodized grating coupler on the silicon- on-insulator (SOI) platform using subwavelength photonic crystals and bonded aluminum mirror. Fabrication error sensitivity andcoupling angle dependence are experimentally investiga......We design and fabricate an ultrahigh coupling efficiency (CE) fully etched apodized grating coupler on the silicon- on-insulator (SOI) platform using subwavelength photonic crystals and bonded aluminum mirror. Fabrication error sensitivity andcoupling angle dependence are experimentally...

  7. Structural rearrangements in the C/W(001) surface system

    International Nuclear Information System (INIS)

    Lyman, P.F.; Mullins, D.R.

    1995-01-01

    We have investigated the surface structure of the C/W(001) surface system at submonolayer C coverages using Auger-electron spectroscopy and high-resolution core-level photoelectron spectroscopy. Core-level spectroscopy is a sensitive probe of an atom's local electronic environment; by examining the core levels of the W atoms in the selvedge region, we monitored the response of the substrate to C adsorption. The average shift of the 4f core-level binding energy provided evidence for a heretofore unknown surface reconstruction that occurs upon submonolayer C adsorption. We also performed line-shape analysis on these core-level spectra, and have thereby elucidated the mechanism by which the low-coverage (√2 x √2 )R45 degree structure evolves to a c(3 √2 x √2 )R45 degree arrangement upon further C adsorption. The line-shape analysis also provides corroborating evidence for a proposed model of the saturated C/W(001)-(5x1) surface structure, and suggests that the first two or three atomic W layers are perturbed by the C adsorption and attendant reconstruction

  8. Efficient 2-μm Tm:YAP Q-switched and CW lasers

    Science.gov (United States)

    Hays, A. D.; Cole, Brian; King, Vernon; Goldberg, Lew

    2018-02-01

    Highly efficient, diode pumped Tm:YAP lasers generating emission in the 1.85-1.94 μm range are demonstrated and characterized. Laser optical efficiencies of 51% and 45%, and electrical efficiencies of 31% and 25% are achieved under CW and Q-switched operation, respectively. Laser performance was characterized for maximum average powers up to 20W with various cavity configurations, all using an intra-cavity lens to compensate for thermal lensing in the Tm:YAP crystal. Q-switched lasers incorportating a Cr:ZnS saturable absorber (SA), resonant mechanical mirror scanner, or acousto-optic modulator were characterized. To enable higher average output powers, measurements of the thermal lens were conducted for the Tm:YAP crystal as a function of pump power and were compared to values predicted by a finiteelement- analysis (FEA) thermal-optical model of the Tm:YAP crystal. A resonator model is developed to incorporate this calculated thermal lens and its effect on laser performance. This paper will address approaches for improving the performance of Tm:YAP lasers, and means for achieving increased average output powers while maintaining high optical efficiency for both SA and mechanical Q-switching.

  9. Damage analysis of fiber reinforced resin matrix composites irradiated by CW laser

    International Nuclear Information System (INIS)

    Wan Hong; Hu Kaiwei; Mu Jingyang; Bai Shuxin

    2008-01-01

    In this paper, the damage modes of the carbon fiber and the glass fiber reinforced epoxy or bakelite resin matrix composites irradiated by CW laser under different power densities were analyzed, and the changes of the microstructure and the tensile strength of the composites were also researched. When the resin matrix composites were radiated at a power density more than 0.1 kW/cm 2 , the matrix would be decomposed and the tensile properties of the radiated samples were lost over 30% while the carbon fiber hardly damaged and the glass fiber melted. When the power density of the laser was raised to 1 kW/cm 2 , the matrix burned violently and the carbon fiber cloth began to split with some carbon fiber being fractured, therefore, the fracture strength of the radiated sample lost over 80%. The higher the power density of radiation was, the more serious the damage of the sample was. It was also found that the difference of the matrixes had little effect on the damage extent of the composites. The influence of the radiation density on the temperature of the radiated surface of the carbon/resin composite was numerically calculated by ANSYS finite element software and the calculation results coincided with the damage mode of the radiated composites. (authors)

  10. RF system developments for CW and/or long pulse linacs

    International Nuclear Information System (INIS)

    Lynch, M.

    1998-01-01

    High Power Proton Linacs are under development or proposed for development at Los Alamos and elsewhere. By current standards these linacs all require very large amounts of RF power. The Accelerator for Production of Tritium (APT) is a CW accelerator with an output current and energy of 100 mA and 1,700 MeV, respectively. The Spallation Neutron Source (SNS), in its ultimate configuration, is a pulsed accelerator with an average output power of 4 MW of beam. Other accelerators such as those that address transmutation and upgrades to LANSCE have similar requirements. For these high average power applications, the RF systems represent approximately half of the total cost of the linac and are thus key elements in the design and configuration of the accelerator. Los Alamos is fortunate to be actively working on both APT and SNS. For these programs the author is pursuing a number of component developments which are aimed at one or more of the key issues for large RF systems: technical performance, capital cost, reliability, and operating efficiency. This paper briefly describes some of the linac applications and then provides updates on the key RF developments being pursued

  11. 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.

  12. 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

    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...... 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...... of the microphone-coupler system in a Boundary Element formulation. In order to obtain a realistic representation of the sound field, viscous losses must be introduced in the model. This paper presents such a model, and the results of the simulations for different combinations of microphones and couplers...

  13. 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.

  14. Design and fabrication of three-dimensional polymer mode multiplexer based on asymmetric waveguide couplers

    Science.gov (United States)

    He, Guobing; Gao, Yang; Xu, Yan; Ji, Lanting; Sun, Xiaoqiang; Wang, Xibin; Yi, Yunji; Chen, Changming; Wang, Fei; Zhang, Daming; Wu, Yuanda

    2018-05-01

    A polymer mode multiplexer based on asymmetric couplers is theoretically designed and experimentally demonstrated. The proposed X-junction coupler is formed by waveguides overlapped with different crossing angles in the vertical direction. A beam propagation method is adopted to optimize the dimensional parameters of the mode multiplexer to convert LP01 mode of two lower waveguides to LP11a and LP21a mode of the upper waveguide. The ultraviolet lithography and wet chemical etching are used in the fabrication process. A conversion ratio over 98% for both LP11a and LP21a mode in the wavelength range from 1530 to 1570 nm are experimentally demonstrated. This mode multiplexer has potential in broadband mode-division multiplexing transmission systems.

  15. The Design of Polymer Planar Optical Triplexer with MMI Filter and Directional Coupler

    Directory of Open Access Journals (Sweden)

    V. Jerabek

    2013-12-01

    Full Text Available Optical bidirectional WDM transceiver is a key component of the Passive Optical Network of the Fiber to the Home topology. Essential parts of such transceivers are filters that combine multiplexing and demultiplexing function of optical signal (triplexing filters. In this paper we report about a design of a new planar optical multi-wavelength selective system triplexing filter, which combines a multimode interference filter with directional coupler based on the epoxy polymer SU-8 on Si/SiO2 substrate. The optical triplexing filter was designed using the Beam Propagation Method. The aim of this project was to optimize the triplexing filter optical parameters and to minimize the planar optical wavelength selective system dimensions. The multimode interference filter was used for separation of downstream optical signal in designed optoelectronic integrated WDM transceiver. The directional coupler was used for adding of upstream optical signal.

  16. Design of a compact polarization beam splitter based on a deformed photonic crystal directional coupler

    International Nuclear Information System (INIS)

    Ren Gang; Zheng Wanhua; Wang Ke; Du Xiaoyu; Xing Mingxin; Chen Lianghui

    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 waveguides 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. (classical areas of phenomenology)

  17. 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.

  18. 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.

  19. Flat-Passband 3 × 3 Interleaving Filter Designed With Optical Directional Couplers in Lattice Structure

    Science.gov (United States)

    Wang, Qi Jie; Zhang, Ying; Soh, Yeng Chai

    2005-12-01

    This paper presents a novel lattice optical delay-line circuit using 3 × 3 directional couplers to implement three-port optical interleaving filters. It is shown that the proposed circuit can deliver three channels of 2pi/3 phase-shifted interleaving transmission spectra if the coupling ratios of the last two directional couplers are selected appropriately. The other performance requirements of an optical interleaver can be achieved by designing the remaining part of the lattice circuit. A recursive synthesis design algorithm is developed to calculate the design parameters of the lattice circuit that will yield the desired filter response. As illustrative examples, interleavers with maximally flat-top passband transmission and with given transmission performance on passband ripples and passband bandwidth, respectively, are designed to verify the effectiveness of the proposed design scheme.

  20. 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.

  1. Thin disk laser with unstable resonator and reduced output coupler

    Science.gov (United States)

    Gavili, Anwar; Shayganmanesh, Mahdi

    2018-05-01

    In this paper, feasibility of using unstable resonator with reduced output coupling in a thin disk laser is studied theoretically. Unstable resonator is modeled by wave-optics using Collins integral and iterative method. An Yb:YAG crystal with 250 micron thickness is considered as a quasi-three level active medium and modeled by solving rate equations of energy levels populations. The amplification of laser beam in the active medium is calculated based on the Beer-Lambert law and Rigrod method. Using generalized beam parameters method, laser beam parameters like, width, divergence, M2 factor, output power as well as near and far-field beam profiles are calculated for unstable resonator. It is demonstrated that for thin disk laser (with single disk) in spite of the low thickness of the disk which leads to low gain factor, it is possible to use unstable resonator (with reduced output coupling) and achieve good output power with appropriate beam quality. Also, the behavior of output power and beam quality versus equivalent Fresnel number is investigated and optimized value of output coupling for maximum output power is achieved.

  2. CW laser properties of Nd:GdYAG, Nd:LuYAG, and Nd:GdLuAG mixed crystals

    Science.gov (United States)

    Di, J. Q.; Xu, X. D.; Li, D. Z.; Zhou, D. H.; Wu, F.; Zhao, Z. W.; Xu, J.; Tang, D. Y.

    2011-10-01

    Three mixed crystals, Nd:GdYAG, Nd:LuYAG, and Nd:GdLuAG, were grown by Czochralski method. We report the continuous-wave (CW) Nd:GdYAG, Nd:LuYAG, and Nd:GdLuAG laser operation under laser diode pumping. The maximum output powers are 4.11, 5.31, and 7.47 W, with slope efficiency of 73.0, 55.3, and 57.1%, respectively. With replacing Lu3+ or Y3+ ions with large Gd3+ ions, the pump efficiency increases.

  3. Development of a 200 W CW high efficiency traveling wave tube at 12 GHz. [for use in communication technology satellites

    Science.gov (United States)

    Christensen, J. A.; Tammaru, I.

    1974-01-01

    The design, development, and test results are reported for an experimental PPM focused, traveling-wave tube that produces 235 watts of CW RF power over 85 MHz centered at 12.080 GHz. The tube uses a coupled cavity RF circuit with a velocity taper for greater than 30 percent basic efficiency. Overall efficiency of 51 percent is achieved by means of a nine stage depressed collector designed at NASA Lewis Research Center. This collector is cooled by direct radiation to deep space.

  4. Measurement of S Parameters ofan Accelerating Structure with Double-Feed Couplers

    CERN Document Server

    Fandos, R; Wuensch, W

    2006-01-01

    A method for measuring the transmission and reflection coefficients of an accelerating structure with double-feed input and output couplers using a 2 port network analyzer is presented. This method avoids the use of magic Ts and hybrids, whose symmetry is not obvious. The procedure is extended to devices with n symmetrical input and m symmetrical output ports. The method to make bead pull measurements for such devices is described.

  5. Switching management in couplers with biharmonic longitudinal modulation of refractive index

    OpenAIRE

    Kartashov, Yaroslav V.; Vysloukh, Victor A.

    2009-01-01

    We address light propagation in couplers with longitudinal biharmonic modulation of refractive index in neighboring channels. While simplest single-frequency out-of-phase modulation allows suppression of coupling for strictly defined set of resonant frequencies, the addition of modulation on multiple frequency dramatically modifies the structure of resonances. Thus, additional modulation on double frequency may suppress primary resonance, while modulation on triple frequency causes fusion of ...

  6. High-efficiency, 154  W CW, diode-pumped Raman fiber laser with brightness enhancement.

    Science.gov (United States)

    Glick, Yaakov; Fromzel, Viktor; Zhang, Jun; Ter-Gabrielyan, Nikolay; Dubinskii, Mark

    2017-01-20

    We demonstrate a high-power, high-efficiency Raman fiber laser pumped directly by laser diode modules at 978 nm. 154 W of CW power were obtained at a wavelength of 1023 nm with an optical to optical efficiency of 65%. A commercial graded-index (GRIN) core fiber acts as the Raman fiber in a power oscillator configuration, which includes spectral selection to prevent generation of the second Stokes. In addition, brightness enhancement of the pump beam by a factor of 8.4 is attained due to the Raman gain distribution profile in the GRIN fiber. To the best of our knowledge this is the highest power and highest efficiency Raman fiber laser demonstrated in any configuration allowing brightness enhancement (i.e., in either cladding-pumped configuration or with GRIN fibers, excluding step-index core pumped), regardless of pumping scheme (i.e., either diode pumped or fiber laser pumped).

  7. 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...

  8. Straightforward and accurate technique for post-coupler stabilization in drift tube linac structures

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Khalvati

    2016-04-01

    Full Text Available 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_{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 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.

  9. 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.

  10. Coupler Development and Gap Field Analysis for the 352 MHz Superconducting CH-Cavity

    CERN Document Server

    Liebermann, H; Ratzinger, U; Sauer, A C

    2004-01-01

    The cross-bar H-type (CH) cavity is a multi-gap drift tube structure based on the H-210 mode currently under development at IAP Frankfurt and in collaboration with GSI. Numerical simulations and rf model measurements showed that the CH-type cavity is an excellent candidate to realize s.c. multi-cell structures ranging from the RFQ exit energy up to the injection energy into elliptical multi-cell cavities. The reasonable frequency range is from about 150 MHz up to 800 MHz. A 19-cell, β=0.1, 352 MHz, bulk niobium prototype cavity is under development at the ACCEL-Company, Bergisch-Gladbach. This paper will present detailed MicroWave Studio simulations and measurements for the coupler development of the 352 MHz superconducting CH cavity. It will describe possibilities for coupling into the superconducting CH-Cavity. The development of the coupler is supported by measurement on a room temperature CH-copper model. We will present the first results of the measurements of different couplers, e.g. capacitiv...

  11. Five-cell superconducting RF module with a PBG coupler cell: design and cold testing of the copper prototype

    Energy Technology Data Exchange (ETDEWEB)

    Arsenyev, Sergey Andreyevich [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Simakov, Evgenya Ivanovna [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Shchegolkov, Dmitry [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Boulware, Chase [Niowave, Lansing, MI (United States); Grimm, Terry [Niowave, Lansing, MI (United States); Rogacki, Adam [Niowave, Lansing, MI (United States)

    2015-04-29

    We report the design and experimental data for a copper prototype of a superconducting radio-frequency (SRF) accelerator module. The five-cell module has an incorporated photonic band gap (PBG) cell with couplers. The purpose of the PBG cell is to achieve better higher order mode (HOM) damping, which is vital for preserving the quality of high-current electron beams. Better HOM damping raises the current threshold for beam instabilities in novel SRF accelerators. The PBG design also increases the real-estate gradient of the linac because both HOM damping and the fundamental power coupling can be done through the PBG cell instead of on the beam pipe via complicated end assemblies. First, we will discuss the design and accelerating properties of the structure. The five-cell module was optimized to provide good HOM damping while maintaining the same accelerating properties as conventional elliptical-cell modules. We will then discuss the process of tuning the structure to obtain the desired accelerating gradient profile. Finally, we will list measured quality factors for the accelerating mode and the most dangerous HOMs.

  12. All-fiber optical mode switching based on cascaded mode selective couplers for short-reach MDM networks

    Science.gov (United States)

    Ren, Fang; Li, Juhao; Wu, Zhongying; Yu, Jinyi; Mo, Qi; Wang, Jianping; He, Yongqi; Chen, Zhangyuan; Li, Zhengbin

    2017-04-01

    We propose and experimentally demonstrate an all-fiber optical mode switching structure supporting independent switching, exchanging, adding, and dropping functionalities in which each mode can be switched individually. The mode switching structure consists of cascaded mode selective couplers (MSCs) capable of exciting and selecting specific higher order modes in few-mode fibers with high efficiency and one multiport optical switch routing the independent spatial modes to their destinations. The data carried on three different spatial modes can be switched, exchanged, added, and dropped through this all-fiber structure. For this experimental demonstration, optical on-off-keying (OOK) signals at 10-Gb/s carried on three spatial modes are successfully processed with open and clear eye diagrams. The mode switch exhibits power penalties of less than 3.1 dB after through operation, less than 2.7 dB after exchange operation, less than 2.8 dB after switching operation, and less than 1.6 dB after mode adding and dropping operations at the bit-error rate (BER) of 10-3, while all three channels carried on three spatial modes are simultaneously routed. The proposed structure, compatible with current optical switching networks based on single-mode fibers, can potentially be used to expand the switching scalability in advanced and flexible short-reach mode-division multiplexing-based networks.

  13. Test result of 5 GHz, 500 kW CW prototype klystron for KSTAR LHCD system

    Energy Technology Data Exchange (ETDEWEB)

    Do, H., E-mail: heejindo@nfri.re.kr [Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Park, S. [Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Jeong, J.H.; Bae, Y.S.; Yang, H.L. [National Fusion Research Institute, Daejeon 350-333 (Korea, Republic of); Delpech, L.; Magne, R.; Hoang, G.T. [CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France); Park, H.; Cho, M.H.; Namkung, W. [Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of)

    2011-10-15

    A 5 GHz LHCD system is being designed for current drive and profile modification necessary for AT mode and steady-state operation of the KSTAR tokamak. A prototype 500 kW CW klystron operating at 5 GHz was developed for the steady-state RF source. In this klystron, a multi-cell cavity is introduced to reduce cavity voltage and ohmic power loss. The klystron is designed with a triode system for optimization of gain, efficiency and beam control. The high voltage for the cathode is turned by using a thyristor switching system at the low voltage transformer unit. For anode voltage control, a mod-anode voltage divider system is used which utilize the parallel-circuit of the FET switch and Zener diodes. The RF output power of the klystron was 300 kW for 800 s and 450 kW for 20 s. The maximal temperature at collector top surface was 83 deg. C and power loss at the tube body did not exceed 10 kW, the interlock level for the protection of the klystron. Detailed results of the klystron system test and commissioning are presented.

  14. Development of a 100 W, single frequency, CW Nd:YAG Laser

    International Nuclear Information System (INIS)

    Veitch, P.J.; Mudge, D.; Munch, J.; Hamilton, M.W.; Ostermeyer, M.; Hosken, D.; Brooks, A.

    2002-01-01

    Full text: High power, diode-laser-pumped, continuous wave (cw) solid-state lasers with excellent beam quality, efficiency and reliability are required for demanding applications, including gravitational wave interferometry, where current additional requirements include single frequency, low noise and Nd:YAG. Our approach is a chain of injection locked laser oscillators, theoretically capable of achieving the lowest noise possible. We use a single-frequency (100 mW) master laser to injection lock a medium-power (10 W) laser that in turn injection locks a 100 W laser. Injection locking requires an optimized, single mode, power slave laser at each stage. We shall describe the nearly completed 10 W brass-board laser, which will also be deployed at the ACIGA Test Facility at Gingin. We shall also describe our 100 W laser using a scalable diode pumping scheme, an active control of thermal lensing and a stable-unstable resonator. Initial tests showed mode control to be limited by thermal focusing and thermally induced birefringence in the Nd:YAG medium at 70 W output. Recent efforts have identified the source of the thermal lens and significantly reduced its magnitude, leading to a modified design. We shall present our latest results from the experiments to demonstrate single mode, single frequency laser at 100 W

  15. Red-light-emitting laser diodes operating cw at room temperature

    International Nuclear Information System (INIS)

    Kressel, H.; Hawrylo, F.Z.

    1976-01-01

    Heterojunction laser diodes of AlGaAs have been prepared with threshold current densities substantially below those previously achieved at room temperature in the 7200 to 8000-A spectral range. These devices operate cw with simple oxide-isolated stripe contacts to 7400 A, which extends cw operation for the first time into the visible (red) portion of the spectrum

  16. CW light sources at the 589 nm sodium D2 line by sum-frequency mixing of diode pumped neodymium lasers

    International Nuclear Information System (INIS)

    Lü, Y F; Lu, J; Xu, L J; Sun, G C; Zhao, Z M; Gao, X; Lin, J Q

    2010-01-01

    We present a laser architecture to obtain continuous-wave (CW) light sources at the 589 nm sodium D2 line. A 808 nm diode-pumped a Nd:YLiF 4 (Nd:YLF) crystal emitting at 1053 nm. A part of the pump power was then absorbed by the Nd:YLF crystal. The remaining was used to pump a Nd:YAG crystal emitting at 1338 nm. Intracavity sum-frequency mixing at 1053 and 1338 nm was then realized in a LiB 3 O 5 (LBO) crystal to reach the yellow-orange radiation. We obtained a CW output power of 235 mW at 589 nm with a pump laser diode emitting 17.8 W at 808 nm

  17. On the possibility of developing quasi-CW high-power high-pressure laser on 4p-4s transition of ArI with electron beam—optical pumping: quenching of 4s (3P2) lower laser level

    Science.gov (United States)

    Ionin, A. A.; Kholin, I. V.; L'dov, A. Yu; Seleznev, L. V.; Ustinovskii, N. N.; Zayarnyi, D. A.

    2017-12-01

    A new electron beam-optical procedure is proposed for quasi-cw pumping of high-pressure large-volume He-Ar laser on the 4p[1/2]1-4s[3/2]20 argon atom transition at the wavelength of 912.5 nm. It consists of creation and maintenance of a necessary density of the 4s[3/2]20 metastable state in the gain medium by a fast electron beam and subsequent optical pumping of the upper laser level via the classical three-level scheme using a laser diode. Absorption probing is used to study collisional quenching of Ar* metastable in electron-beam-excited high-pressure He-Ar mixtures with a low content of argon. The rate constants for plasma-chemical reactions Ar*  +  He  +  Ar  >  Ar2*   +  He (3.6  ±  0.4)  ×  10-33 cm6 s-1, Ar*  +  2He  >  HeAr*  +  He (4.4  ±  0.9)  ×  10-36 cm6 s-1 and Ar*  +  He  >  Products  +  He (2.4  ±  0.3)  ×  10-15 cm3 s-1 were for the first time measured.

  18. Maximum Available Accuracy of FM-CW Radars

    Directory of Open Access Journals (Sweden)

    V. Ricny

    2009-12-01

    Full Text Available This article deals with the principles and above all with the maximum available measuring accuracy analyse of FM-CW (Frequency Modulated Continuous Wave radars, which are usually employed for distance and velocity measurements of moving objects in road traffic, as well as air traffic and in other applications. These radars often form an important part of the active safety equipment of high-end cars – the so-called anticollision systems. They usually work in the frequency bands of mm waves (24, 35, 77 GHz. Function principles and analyses of factors, that dominantly influence the distance measurement accuracy of these equipments especially in the modulation and demodulation part, are shown in the paper.

  19. Internal optical losses in very thin CW heterojunction laser diodes

    Science.gov (United States)

    Butler, J. K.; Kressel, H.; Ladany, I.

    1975-01-01

    Theoretical calculations are presented showing the relationship between the internal laser absorption and structural parameters appropriate for CW room-temperature lasers. These diodes have submicron-thick recombination regions, and very small spacings between the heat sink and the recombination region to minimize the thermal resistance. The optical loss is shown to be strongly dependent on the degree of radiation confinement to the active region. In particular, absorption in the surface GaAs layer providing the ohmic contact becomes very significant when the intermediate (AlGa)As layer is reduced below about 1 micron. It is further shown that excessive penetration into the GaAs regions gives rise to anomalies in the far-field radiation profiles in the direction perpendicular to the junction plane.

  20. Study of pseudo noise CW diode laser for ranging applications

    Science.gov (United States)

    Lee, Hyo S.; Ramaswami, Ravi

    1992-01-01

    A new Pseudo Random Noise (PN) modulated CW diode laser radar system is being developed for real time ranging of targets at both close and large distances (greater than 10 KM) to satisy a wide range of applications: from robotics to future space applications. Results from computer modeling and statistical analysis, along with some preliminary data obtained from a prototype system, are presented. The received signal is averaged for a short time to recover the target response function. It is found that even with uncooperative targets, based on the design parameters used (200-mW laser and 20-cm receiver), accurate ranging is possible up to about 15 KM, beyond which signal to noise ratio (SNR) becomes too small for real time analog detection.

  1. Apsidal Motion Study of Close Binary System CW Cephei

    Directory of Open Access Journals (Sweden)

    Wonyong Han

    2015-12-01

    Full Text Available New observations for the times of minimum lights of a well-known apsidal motion star CW Cephei were made using a 0.6 m wide field telescope at Jincheon station of Chungbuk National University Observatory, Korea during the 2015 observational season. We determined new times of minimum lights from these observations and analyzed O-C diagrams together with collected times of minima to study both the apsidal motion and the Light Time Effect (LTE suggested in the system. The new periods of the apsidal motion and the LTE were calculated as 46.6 and 39.3 years, respectively, which were similar but improved accuracy than earlier ones investigated by Han et al. (2002, Erdem et al. (2004 and Wolf et al. (2006.

  2. Emittance compensation of CW DC-gun photoinjector

    International Nuclear Information System (INIS)

    Li Peng; Wu Dai; Xu Zhou; Li Ming; Yang Xingfan

    2011-01-01

    Emittance growth induced by space charge effect is very important, especially for CW DC-gun photoinjector. In this work, the linear space charge force and its effect on electron beam transverse emittance are studied, and the principle and properties of emittance compensation by solenoid are analyzed. The CAEP DC-gun photoinjector with a solenoid is also simulated by code Parmela. Simulated results indicate that the normalized transverse emittance of an 80 pC bunch at the 350 keV DC-gun ex-it is 5.14 mm · mrad. And after compensated by a solenoid, it becomes 1.27 mm · mrad. The emittance of beam is well compensated. (authors)

  3. Detailed characterization of CW- and pulsed-pump four-wave mixing in highly nonlinear fibers

    DEFF Research Database (Denmark)

    Lillieholm, Mads; Galili, Michael; Grüner-Nielsen, L.

    2016-01-01

    We present a quantitative comparison of continuouswave- (CW) and pulsed-pump four-wave mixing (FWM) in commercially available highly nonlinear fibers (HNLFs), and suggest properties for which the CW and pulsed FWM bandwidths are limited in practice. The CWand pulsed-pump parametric gain is charac......We present a quantitative comparison of continuouswave- (CW) and pulsed-pump four-wave mixing (FWM) in commercially available highly nonlinear fibers (HNLFs), and suggest properties for which the CW and pulsed FWM bandwidths are limited in practice. The CWand pulsed-pump parametric gain...... bandwidth. However, an inverse scaling of the TOD with the dispersion fluctuations, leads to different CW-optimized fibers, which depend only on the even dispersion-orders....

  4. Experimental verification of the air kerma to absorbed dose conversion factor Cw,u.

    Science.gov (United States)

    Mijnheer, B J; Wittkämper, F W; Aalbers, A H; van Dijk, E

    1987-01-01

    In a recently published code of practice for the dosimetry of high-energy photon beams, the absorbed dose to water is determined using an ionization chamber having an air kerma calibration factor and applying the air kerma to absorbed dose conversion factor Cw,u. The consistency of these Cw,u values has been determined for four commonly employed types of ionization chambers in photon beams with quality varying between 60Co gamma-rays and 25 MV X-rays. Using a graphite calorimeter, Cw,u has been determined for a graphite-walled ionization chamber (NE 2561) for the same qualities. The values of Cw,u determined with the calorimeter are within the experimental uncertainty equal to Cw,u values determined according to any of the recent dosimetry protocols.

  5. Diode-pumped CW frequency-doubled Nd:CNGG-BiBO blue laser at 468 nm

    International Nuclear Information System (INIS)

    Lü, Y F; Xia, J; Lin, J Q; Gao, X; Dong, Y; Xu, L J; Sun, G C; Zhao, Z M; Tan, Y; Chen, J F; Liu, Z X; Li, C L; Cai, H X; Liu, Z T; Ma, Z Y; Ning, G B

    2011-01-01

    Efficient and compact blue laser output at 468 nm is generated by intracavity frequency doubling of a continuous-wave (CW) diode-pumped Nd:CNGG laser at 935 nm. With 17.8 W of diode pump power and the frequency-doubling crystal BiB 3 O 6 (BiBO), a maximum output power of 490 mW in the blue spectral range at 468 nm has been achieved, corresponding to an optical-to-optical conversion efficiency of 2.8%; the output power stability over 4 h is better than 2.6%. To the best of our knowledge, this is first work on intracavity frequency doubling of a diode pumped Nd:CNGG laser at 935 nm

  6. Preliminary design of high-power wave-guide/transmission system ...

    Indian Academy of Sciences (India)

    . This LINAC will be needing CW rf power in the frequency ranges of 350 MHz and 700 MHz for its RFQ and. DTL/CCDTL/SFDTL structures respectively. The power to the accelerating structures will be pro- duced by either 1 MW CW or 250 kW ...

  7. Diseño y validación de un radar CW-FM a 94 GHz

    OpenAIRE

    Varela Agrelo, David

    2013-01-01

    Diseño y validación de un radar CW-FM a 9g GHz 94 GHz CW-FM radar design and mesurement campaign validation. Desarrollo de un radar CW-FM a 94GHz y verificación de los resultados obtenidos durante la etapa de medidas. Desevolupament d'un radar CW-FM a 94GHz i verificació dels resultat obteinguts durante l'etapa de mesures.

  8. Nanoantenna couplers for metal-insulator-metal waveguide interconnects

    Science.gov (United States)

    Onbasli, M. Cengiz; Okyay, Ali K.

    2010-08-01

    State-of-the-art copper interconnects suffer from increasing spatial power dissipation due to chip downscaling and RC delays reducing operation bandwidth. Wide bandwidth, minimized Ohmic loss, deep sub-wavelength confinement and high integration density are key features that make metal-insulator-metal waveguides (MIM) utilizing plasmonic modes attractive for applications in on-chip optical signal processing. Size-mismatch between two fundamental components (micron-size fibers and a few hundred nanometers wide waveguides) demands compact coupling methods for implementation of large scale on-chip optoelectronic device integration. Existing solutions use waveguide tapering, which requires more than 4λ-long taper distances. We demonstrate that nanoantennas can be integrated with MIM for enhancing coupling into MIM plasmonic modes. Two-dimensional finite-difference time domain simulations of antennawaveguide structures for TE and TM incident plane waves ranging from λ = 1300 to 1600 nm were done. The same MIM (100-nm-wide Ag/100-nm-wide SiO2/100-nm-wide Ag) was used for each case, while antenna dimensions were systematically varied. For nanoantennas disconnected from the MIM; field is strongly confined inside MIM-antenna gap region due to Fabry-Perot resonances. Major fraction of incident energy was not transferred into plasmonic modes. When the nanoantennas are connected to the MIM, stronger coupling is observed and E-field intensity at outer end of core is enhanced more than 70 times.

  9. Cavity-Enhanced Raman Spectroscopy of Natural Gas with Optical Feedback cw-Diode Lasers.

    Science.gov (United States)

    Hippler, Michael

    2015-08-04

    We report on improvements made on our previously introduced technique of cavity-enhanced Raman spectroscopy (CERS) with optical feedback cw-diode lasers in the gas phase, including a new mode-matching procedure which keeps the laser in resonance with the optical cavity without inducing long-term frequency shifts of the laser, and using a new CCD camera with improved noise performance. With 10 mW of 636.2 nm diode laser excitation and 30 s integration time, cavity enhancement achieves noise-equivalent detection limits below 1 mbar at 1 bar total pressure, depending on Raman cross sections. Detection limits can be easily improved using higher power diodes. We further demonstrate a relevant analytical application of CERS, the multicomponent analysis of natural gas samples. Several spectroscopic features have been identified and characterized. CERS with low power diode lasers is suitable for online monitoring of natural gas mixtures with sensitivity and spectroscopic selectivity, including monitoring H2, H2S, N2, CO2, and alkanes.

  10. Side-pumped Nd:YVO4 cw laser with grazing-incidence small angle configuration

    International Nuclear Information System (INIS)

    Camargo, Fabiola de Almeida

    2006-01-01

    Within the existing variety of laser cavity geometries and gain materials there is one combination that is particularly interesting because of its reduced complexity and high efficiency: the edge-pumped slab-laser using grazing-incidence geometry and a gain media with a very high pump absorption cross-section. In this work we studied a diode side-pumped Nd:YVO 4 cw laser. We describe a single and a multiple bounce laser configurations. We demonstrate 22 W of multimode output power for 35 watts of pump power with a single pass through the gain media. A high optical-to-optical conversion efficiency of 63% and a slope efficiency of 74% with a very compact and simple Nd:YVO 4 cavity that uses joint stability zones was achieved. The beam quality was M 2 = 26 x 11 in the horizontal and vertical direction, respectively. With a double pass configuration we achieved 17 watts with a better beam quality of M 2 = 3,4 x 3,7, in the horizontal and vertical direction, respectively. (author)

  11. New configurations for short-pulses high power solid-state lasers: conception and realization of highly doped waveguide amplifiers/lasers grown by liquid phase epitaxy and demonstration of Y2SiO5: Yb and Lu2SiO5: Yb femtosecond lasers

    International Nuclear Information System (INIS)

    Thibault, F.

    2006-04-01

    Yb-doped yttrium and lutetium ortho-silicates, Y 2 SiO 5 :Yb and Lu 2 SiO 5 :Yb respectively, exhibit spectroscopic properties favorable to an efficient laser operation in both high power cw and femtosecond regime. Their first diode-pumped femtosecond operation demonstration lead to exceptional performances in terms of output power and efficiency. In order to realize compact and efficient solid-state laser devices using those materials, we chose a configuration with an Yb-doped medium planar waveguide geometry, grown by liquid phase epitaxy, face-pumped by a single laser diode bar. The growth of highly doped Y 2 SiO 5 :Yb layers, within a large range of compositions and thicknesses, was demonstrated. The refractive index increase due to the substitution of the various dopants is analyzed. The layers spectroscopic properties are similar to the bulk ones, with an noticeably higher crystalline quality. The Yb ion lifetime evolution with respect to its doping shows up a particularly low decrease, proof of a low concentration of extrinsic quenching centers. The covered YSO:24%Yb waveguides exhibit lower than 0.3 dB/cm propagation losses, and provided up to 2.9 dB/cm net amplification at 1082 nm with a single mode output. The realization of the first diode-pumped monolithic cw waveguide lasers was also demonstrated. For a 4% output coupler, they provided up to 340 mW at 1082 nm with a 14% slope efficiency. (author)

  12. Comparison of isolate dadih with yeast dadih in improving nutrition quality of Cassava Waste (CW)

    Science.gov (United States)

    Ginting, N.

    2018-03-01

    The cassava industry in North Sumatra Province was one of the most significant agricultural industries. Waste from the cassava industry which was called cassava waste/CW/Onggok was used as feed for ruminants such as cattle, sheep and monogastric such as pigs. The low nutrients in CW caused the need to find a way for improving the nutrients quality. This research was conducted with the aim to help livestockers to ferment their livestock feed. This study compared the ability of fermentation between dadih isolate with dadih yeast. Dadih is traditional food in Indonesia where milk is fermented in bamboo tube. Dadih yeast was made by mixing dadih and whey with flour, made in around shape and sun dried. The results showed that pH of CW by dadih isolate was the lowest while crude protein, crude fiber and fat in CW treated with dadih isolate were improved significantly compared either to control or to dadih starter while fermented CW was better than non-fermented CW. It was recommended livestockers to ferment CW by using either by dadih isolate or dadih starter.

  13. Multicenter Clinical Trial of Vibroplasty Couplers to Treat Mixed/Conductive Hearing Loss: First Results.

    Science.gov (United States)

    Zahnert, Thomas; Löwenheim, Hubert; Beutner, Dirk; Hagen, Rudolf; Ernst, Arneborg; Pau, Hans-Wilhelm; Zehlicke, Thorsten; Kühne, Hilke; Friese, Natascha; Tropitzsch, Anke; Lüers, Jan-Christoffer; Mlynski, Robert; Todt, Ingo; Hüttenbrink, Karl-Bernd

    2016-01-01

    To evaluate the safety and effectiveness of round window (RW), oval window (OW), CliP and Bell couplers for use with an active middle ear implant. This is a multicenter, long-term, prospective trial with consecutive enrollment, involving 6 university hospitals in Germany. Bone conduction, air conduction, implant-aided warble-tone thresholds and Freiburger monosyllable word recognition scores were compared with unaided preimplantation results in 28 moderate-to-profound hearing-impaired patients after 12 months of follow-up. All patients had previously undergone failed reconstruction surgeries (up to 5 or more). In a subset of patients, additional speech tests at 12 months postoperatively were used to compare the aided with the unaided condition after implantation with the processor switched off. An established quality-of-life questionnaire for hearing aids was used to determine patient satisfaction. Postoperative bone conduction remained stable. Mean functional gain for all couplers was 37 dB HL (RW = 42 dB, OW = 35 dB, Bell = 38 dB, CliP = 27 dB). The mean postoperative Freiburger monosyllable score was 71% at 65 dB SPL. The postimplantation mean SRT50 (speech reception in quiet for 50% understanding of words in sentences) improved on average by 23 dB over unaided testing and signal-to-noise ratios also improved in all patients. The International Outcome Inventory for Hearing Aids (IOI-HA)quality-of-life questionnaire was scored very positively by all patients. A significant improvement was seen with all couplers, and patients were satisfied with the device at 12 months postoperatively. These results demonstrate that an active implant is an advantage in achieving good hearing benefit in patients with prior failed reconstruction surgery. © 2016 S. Karger AG, Basel.

  14. TM grating coupler on low-loss LPCVD based Si3N4 waveguide platform

    Science.gov (United States)

    Dabos, G.; Manolis, A.; Giesecke, A. L.; Porschatis, C.; Chmielak, B.; Wahlbrink, T.; Pleros, N.; Tsiokos, D.

    2017-12-01

    We demonstrate, for the first time to our knowledge, a fully etched TM grating coupler for low-loss Low-Pressure-Chemical-Vapor-Deposition (LPCVD) based silicon nitride platform with a coupling loss of 6.5 dB at 1541 nm and a 1 dB bandwidth of 55 nm, addressing applications where TM polarization is a pre-requisite. The proposed GC and the 360 nm × 800 nm strip based Si3N4 waveguides have been fabricated by optical projection lithography using an i-line stepper tool enabling low-cost and mass manufacturing of photonic-integrated-circuits.

  15. OPTICAL FIBRES AND FIBREOPTIC SENSORS: Fibreoptic distributed temperature sensor with spectral filtration by directional fibre couplers

    Science.gov (United States)

    Kuznetsov, A. G.; Babin, Sergei A.; Shelemba, Ivan S.

    2009-11-01

    We demonstrate a Raman-based all-fibre temperature sensor utilising a pulsed erbium fibre laser. The sensor is made of a standard single-mode telecom fibre, SMF-28, and includes a number of directional couplers as band-pass filters. The temperature profile along a 7-km fibreoptic line is measured with an accuracy of 2oC and a spatial resolution of 10 m. In data processing, we take into account the difference in attenuation between the spectral components of the backscatter signal.

  16. Liquid droplet sensing using twisted optical fiber couplers fabricated by hydrofluoric acid flow etching

    Science.gov (United States)

    Son, Gyeongho; Jung, Youngho; Yu, Kyoungsik

    2017-04-01

    We report a directional-coupler-based refractive index sensor and its cost-effective fabrication method using hydrofluoric acid droplet wet-etching and surface-tension-driven liquid flows. The proposed fiber sensor consists of a pair of twisted tapered optical fibers with low excess losses. The fiber cores in the etched microfiber region are exposed to the surrounding medium for efficient interaction with the guided light. We observe that the etching-based low-loss fiber-optic sensors can measure the water droplet volume by detecting the refractive index changes of the surrounding medium around the etched fiber core region.

  17. High efficiency and broad bandwidth grating coupler between nanophotonic waveguide and fibre

    International Nuclear Information System (INIS)

    Yu, Zhu; Xue-Jun, Xu; Zhi-Yong, Li; Liang, Zhou; Yu-De, Yu; Jin-Zhong, Yu; Wei-Hua, Han; Zhong-Chao, Fan

    2010-01-01

    A high efficiency and broad bandwidth grating coupler between a silicon-on-insulator (SOI) nanophotonic waveguide and fibre is designed and fabricated. Coupling efficiencies of 46% and 25% at a wavelength of 1.55 μm are achieved by simulation and experiment, respectively. An optical 3 dB bandwidth of 45 nm from 1530 nm to 1575 nm is also obtained in experiment. Numerical calculation shows that a tolerance to fabrication error of 10 nm in etch depth is achievable. The measurement results indicate that the alignment error of ±2 μm results in less than 1 dB additional coupling loss. (classical areas of phenomenology)

  18. A novel highly efficient grating coupler with large filling factor used for optoelectronic integration

    International Nuclear Information System (INIS)

    Zhou Liang; Li Zhi-Yong; Zhu Yu; Li Yun-Tao; Yu Yu-De; Yu Jin-Zhong; Fan Zhong-Cao; Han Wei-Hua

    2010-01-01

    A novel highly efficient grating coupler with large filling factor and deep etching is proposed in silicon-on-insulator for near vertical coupling between the rib waveguide and optical fibre. The deep slots acting as high efficient scattering centres are analysed and optimized. As high as 60% coupling efficiency at telecom wavelength of 1550-nm and 3-dB bandwidth of 61 nm are predicted by simulation. A peak coupling efficiency of 42.1% at wavelength 1546-nm and 3-dB bandwidth of 37.6 nm are obtained experimentally. (classical areas of phenomenology)

  19. A grating coupler with a trapezoidal hole array for perfectly vertical light coupling between optical fibers and waveguides

    Science.gov (United States)

    Mizutani, Akio; Eto, Yohei; Kikuta, Hisao

    2017-12-01

    A grating coupler with a trapezoidal hole array was designed and fabricated for perfectly vertical light coupling between a single-mode optical fiber and a silicon waveguide on a silicon-on-insulator (SOI) substrate. The grating coupler with an efficiency of 53% was computationally designed at a 1.1-µm-thick buried oxide (BOX) layer. The grating coupler and silicon waveguide were fabricated on the SOI substrate with a 3.0-µm-thick BOX layer by a single full-etch process. The measured coupling efficiency was 24% for TE-polarized light at 1528 nm wavelength, which was 0.69 times of the calculated coupling efficiency for the 3.0-µm-thick BOX layer.

  20. CW and AO Q-switched operation of a dual-crystal Tm, Ho:GdVO4 laser pumped by two diodes

    International Nuclear Information System (INIS)

    Li, L J; Bai, Y F; Liu, Y W; He, Z L; Wang, J; Yao, B Q; Zhou, S; Xing, M N

    2013-01-01

    Continuous wave (CW) mode and acousto-optic (AO) Q-switched mode operation of a dual-crystal Tm, Ho:GdVO 4 laser is reported. The dual-crystal Tm, Ho:GdVO 4 laser with output wavelength of 2.05 μm was pumped by two laser diodes (LDs). The Tm, Ho:GdVO 4 crystals were cooled by liquid nitrogen and pumped by two fiber-coupled LDs with a center output wavelength of 801.0 nm. A 20.5 W output power was obtained at a 255 mm physical cavity length in CW mode operation, and a 19.6 W average power was obtained at a pulse repetition frequency (PRF) of 10 kHz with a 19 ns pulse duration. Also, the efficiency loss of the laser is not more than 4.4% from CW mode to Q-switch mode, and the M 2 factor, which is measured by the traveling knife-edge method, does not exceed 1.2. (paper)

  1. High-energy, high-repetition-rate picosecond pulses from a quasi-CW diode-pumped Nd:YAG system.

    Science.gov (United States)

    Noom, Daniel W E; Witte, Stefan; Morgenweg, Jonas; Altmann, Robert K; Eikema, Kjeld S E

    2013-08-15

    We report on a high-power quasi-CW pumped Nd:YAG laser system, producing 130 mJ, 64 ps pulses at 1064 nm wavelength with a repetition rate of 300 Hz. Pulses from a Nd:YVO(4) oscillator are first amplified by a regenerative amplifier to the millijoule level and then further amplified in quasi-CW diode-pumped Nd:YAG modules. Pulsed diode pumping enables a high gain at repetition rates of several hundred hertz, while keeping thermal effects manageable. Birefringence compensation and multiple thermal-lensing-compensated relay-imaging stages are used to maintain a top-hat beam profile. After frequency doubling, 75 mJ pulses are obtained at 532 nm. The intensity stability is better than 1.1%, which makes this laser an attractive pump source for a high-repetition-rate optical parametric amplification system.

  2. Generation of nanosecond laser pulses at a 2.2-MHz repetition rate by a cw diode-pumped passively Q-switched Nd3+:YVO4 laser

    International Nuclear Information System (INIS)

    Nghia, Nguyen T; Hao, Nguyen V; Orlovich, Valentin A; Hung, Nguyen D

    2011-01-01

    We report a new configuration of a high-repetition rate nanosecond laser based on a semiconductor saturable absorber mirror (SESAM). The SESAM is conventional technical solution for passive mode-locking at 1064 nm and simultaneously used as a highly reflecting mirror and a saturable absorber in a high-Q and short cavity of a cw diode-end-pumped a-cut Nd 3+ :YVO 4 laser. Two laser beams are coupled out from the cavity using an intracavity low-reflection thin splitter. The laser characteristics are investigated as functions of pump and resonator parameters. Using a 1.8-W cw pump laser diode at 808 nm, the passively Q-switched SESAMbased laser generates 22-ns pulses with an average power of 275 mW at a pulse repetition rate of 2250 kHz.

  3. First lasing of the Darmstadt cw free electron laser

    CERN Document Server

    Brunken, M; Eichhorn, R; Genz, H; Gräf, H D; Loos, H; Richter, A; Schweizer, B; Stascheck, A; Wesp, T

    1999-01-01

    The Darmstadt CW FEL designed for wavelengths between 3 and 10 mu m driven by the superconducting electron accelerator S-DALINAC first lased on December 1st, 1996 and has operated thereafter successfully in the wavelength region between 6.6 and 7.8 mu m. The pulsed electron beam employed had a micro pulse length of about 2ps, with a repetition rate of 10 MHz and a peak current of 2.7 A while its energy was varied between 29.6 and 31.5 MeV. A wedged pole hybrid undulator, with 80 periods each of 0.032 m length and a magnetic field strength of 0.15-0.4T, was located in between a 15.01 m long optical cavity equipped with two high reflectivity (99.8) mirrors of 0.05 m diameter. Due to the low beam current special care with respect to the electron and optical beam properties was necessary to meet the stringent conditions in order to reach a minute small signal gain of at least a few percent resulting in amplification. Saturation was obtained after about 2000 repetitions of the photon pulse inside the cavity. The D...

  4. Sea-dumped CW munitions - the European component

    International Nuclear Information System (INIS)

    Hart, J.; Stock, T.

    2009-01-01

    The purpose of this contribution is to outline the European magnitude of sea-dumped CW munitions. Hereby the paper attempts to provide an overview on historical dumping activities, both for conventional and chemical munitions. The potential dangers which might result from these dumping activities are discussed in brief. Among others the differences in deep sea dumping and dumping in shallow waters are evaluated. Further, the presentation will outline and discuss the different technology steps: (a) identification, (b) recovery, (c) transportation and (d) destruction (on- or off-shore), necessary for possible cleaning of dumping sites. Thereafter an evaluation of the different technologies available/applied is performed, in particular on the destruction part. Hereby the already practised experience is displayed. Based upon existing treaty regimes an actual judgment of possible application of treaty provisions for demanding cleaning up operations is discussed. The question if treaty obligations can be used to force cleaning operations is debated. A possible match of the technology package available with the scope/magnitude of the munitions dumping problem is discussed. Hereby the gaps between the size of the problem and the most suitable technologies for recovery and destruction are illustrated. The resulting answers should be regarded as possible technical guidelines for future development activities as well existing limitations to solve the problems. The papers will result in some general guidelines for future prospect on the issues of dumped munitions, in particular chemical munitions under the European context.(author)

  5. Internal optical losses in very thin cw heterojunction laser diodes

    International Nuclear Information System (INIS)

    Butler, J.K.; Kressel, H.; Ladany, I.

    1975-01-01

    Theoretical calculations are presented showing the relationship between the internal laser absorption and structural parameters appropriate for cw room-temperature lasers. These diodes have submicron-thick recombination regions, and very small spacings between the heat sink and the recombination region to minimize the thermal resistance. The optical loss is shown to be strongly dependent on the degree of radiation confinement to the active region. In particular, absorption in the surface GaAs layer providing the ohmic contact becomes very significant when the intermediate (AlGa)As layer is reduced below about 1 μm. It is further shown that excessive penetration into the GaAs regions gives rise to anomalies in the far-field radiation profiles in the direction perpendicular to the junction plane. Proper design of the internal structure of the laser avoids large increases of the threshold current density as well as large decreases in the external differential quantum efficiency from interaction with the contact layer. The design curves presented can be used to predict the gain required at threshold for a broad range of structural parameters of interest in low-threshold laser design

  6. CW/Pulsed H- ion beam generation with PKU Cs-free 2.45 GHz microwave driven ion source

    Science.gov (United States)

    Peng, S. X.; Ren, H. T.; Xu, Y.; Zhang, T.; Zhang, A. L.; Zhang, J. F.; Zhao, J.; Guo, Z. Y.; Chen, J. E.

    2015-04-01

    Circular accelerators used for positron emission tomography (PET, i.e. accelerator used for make radio isotopes) need several mA of CW H- ion beam for their routine operation. Other facilities, like Space Radio-Environment Simulate Assembly (SPRESA), require less than 10 mA pulsed mode H- beam. Caesium free negative hydrogen ion source is a good choice for those facilities because of its compact structure, easy operation and low cost. Up to now, there is no H- source able to produce very intense H- beams with important variation of the duty factor[1]. Recently, a new version of 2.45 GHz microwave H- ion source was designed at PKU, based on lessons learnt from the previous one. This non cesiated source is very compact thanks to its permanent magnet configuration. Special attention was paid on the design of the discharge chamber structure, electron dumping and extraction system. Source test to produce H- ion beams in pulsed and CW mode was carried out on PKU ion source test bench. In CW mode, a 10.8 mA/30keV H- beam with rms emittance about 0.16 π.mm.mrad has been obtained with only 500 W rf power. The power efficiency reaches 21 mA/kW. In pulsed mode with duty factor of 10% (100Hz/1ms), this compact source can easily deliver 20 mA H- ion beam at 35 keV with rms emittance about 0.2 π.mm.mrad when RF power is set at 2.2 kW (peak power). Several hour successive running operation in both modes and totaling more than 200 hours proves its high quality. The outside dimension of this new H- source body is ϕ116 mm × 124 mm, and the entire H- source infrastructure, including rf matching section, plasma chamber and extraction system, is ϕ310 × 180 mm. The high voltage region is limited with in a ϕ310 mm × 230 mm diagram. Details are given in this paper.

  7. Analytical modeling and analysis of magnetic field and torque for novel axial flux eddy current couplers with PM excitation

    Science.gov (United States)

    Li, Zhao; Wang, Dazhi; Zheng, Di; Yu, Linxin

    2017-10-01

    Rotational permanent magnet eddy current couplers are promising devices for torque and speed transmission without any mechanical contact. In this study, flux-concentration disk-type permanent magnet eddy current couplers with double conductor rotor are investigated. Given the drawback of the accurate three-dimensional finite element method, this paper proposes a mixed two-dimensional analytical modeling approach. Based on this approach, the closed-form expressions of magnetic field, eddy current, electromagnetic force and torque for such devices are obtained. Finally, a three-dimensional finite element method is employed to validate the analytical results. Besides, a prototype is manufactured and tested for the torque-speed characteristic.

  8. Two-wavelength, passive self-injection-controlled operation of diode-pumped cw Yb-doped crystal lasers.

    Science.gov (United States)

    Louyer, Yann; Wallerand, Jean-Pierre; Himbert, Marc; Deneva, Margarita; Nenchev, Marin

    2003-09-20

    We demonstrate and investigate a peculiar mode of cw Yb3+-doped crystal laser operation when two emissions, at two independently tunable wavelengths, are simultaneously produced. Both emissions are generated from a single pumped volume and take place in either a single beam or spatially separated beams. The laser employs original two-channel cavities that use a passive self-injection-locking (PSIL) control to reduce intracavity loss. The advantages of the application of the PSIL technique and some limitations are shown. The conditions for two-wavelength multimode operation of the cw quasi-three-level diode-pumped Yb3+ lasers and the peculiarity of such an operation are carried out both theoretically and experimentally. The results reported are based on the example of a Yb3+:GGG laser but similar results are also obtained with a Yb3+:YAG laser. The laser operates in the 1023-1033-nm (1030-1040-nm) range with a total output power of 0.4 W. A two-wavelength, single longitudinal mode generation is also obtained.

  9. 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.

  10. All-optical universal logic gates on nonlinear multimode interference coupler using tunable input intensity

    Science.gov (United States)

    Tajaldini, Mehdi; Jafri, Mohd Zubir Mat

    2015-04-01

    The theory of Nonlinear Modal Propagation Analysis Method (NMPA) have shown significant features of nonlinear multimode interference (MMI) coupler with compact dimension and when launched near the threshold of nonlinearity. Moreover, NMPA have the potential to allow studying the nonlinear MMI based the modal interference to explorer the phenomenon that what happen due to the natural of multimode region. Proposal of all-optical switch based NMPA has approved its capability to achieving the all-optical gates. All-optical gates have attracted increasing attention due to their practical utility in all-optical signal processing networks and systems. Nonlinear multimode interference devices could apply as universal all-optical gates due to significant features that NMPA introduce them. In this Paper, we present a novel Ultra-compact MMI coupler based on NMPA method in low intensity compared to last reports either as a novel design method and potential application for optical NAND, NOR as universal gates on single structure for Boolean logic signal processing devices and optimize their application via studding the contrast ratio between ON and OFF as a function of output width. We have applied NMPA for several applications so that the miniaturization in low nonlinear intensities is their main purpose.

  11. 2×2 polymeric electro-optic MZI switch using multimode interference couplers

    Science.gov (United States)

    Li, H. P.; Liao, J. K.; Tang, X. G.; Lu, R. G.; Liu, Y. Z.

    2009-11-01

    We present the design of a 2×2 photonic switch operating at 1.55-μm wavelength using electro-optic (EO) polymer waveguides. A Mach-Zehnder interferometer (MZI) is used to implement the proposed switch in which two identical 2×2 multimode interference (MMI) couplers are connected by two identical parallel single mode waveguides (two MZI arms). These two single-mode waveguides with electrodes allow modulating the phase difference between the two MZI arms based on the EO effect. In the proposed switch, the EO polymer, IPC-E/polysulfone, is used for the core layer of optical waveguides. UV15 and NOA61 are employed for the lower and upper cladding layers, respectively. The singlemode waveguide structure and 2×2 MMI coupler have been designed and analyzed for the EO switch. Device performance has been simulated using the beam propagation method. It is found that the switch performance is most sensitive to the MMI width and less sensitive to the MMI length. Optimized structure has been obtained for the 2×2 polymeric EO switch, which has a crosstalk level better than -25 dB and insertion loss lower than -1.8 dB. This performance makes the switch a potential candidate for practical use in photonic systems.

  12. A new approach to model CW CO2 laser using rate equations

    Indian Academy of Sciences (India)

    2016-11-11

    Nov 11, 2016 ... Abstract. Two popular methods to analyse the operation of CW CO2 lasers use the temperature model and ... Grouping of the vibration levels helped in restrict- ..... [10] D C Tyte, Carbon dioxide lasers, in: Advances in quan-.

  13. Cw hyper-Raman laser and four-wave mixing in atomic sodium

    Science.gov (United States)

    Klug, M.; Kablukov, S. I.; Wellegehausen, B.

    2005-01-01

    Continuous wave hyper-Raman (HR) generation in a ring cavity on the 6s → 4p transition at 1640 nm in sodium is realized for the first time by two-photon excitation of atomic sodium on the 3s → 6s transition with a continuous wave (cw) dye laser at 590 nm and a single frequency argon ion laser at 514 nm. It is shown, that the direction and efficiency of HR lasing depends on the propagation direction of the pump waves and their frequencies. More than 30% HR gain is measured at 250 mW of pump laser powers for counter-propagating pump waves and a medium length of 90 mm. For much shorter interaction lengths and corresponding focussing of the pump waves a dramatic increase of the gain is predicted. For co-propagating pump waves, in addition, generation of 330 nm radiation on the 4p → 3s transition by a four-wave mixing (FWM) process is observed. Dependencies of HR and parametric four-wave generation have been investigated and will be discussed.

  14. Slow positron beam production by a 14 MeV C.W. electron accelerator

    Science.gov (United States)

    Begemann, M.; Gräff, G.; Herminghaus, H.; Kalinowsky, H.; Ley, R.

    1982-10-01

    A 14 MeV c.w. electron accelerator is used for pair production in a tungsten target of 0.7 radiation lengths thickness. A small fraction of the positrons is thermalized and diffuses out of the surface ofsurface of a well annealed tungsten foil coated with MgO which is positioned immediately behind the target. The slow positrons are extracted from the target region and magnetically guided over a distance of 10 m onto a channelplate multiplier at the end of an S-shaped solenoid. The positrons are identified by their annihilation radiation using two NaI-detectors. The intensity of the slow positrons is proportional to the accelerator electron beam current. The maximum intensity of 2.2 × 10 5 slow positrons per second reaching thedetector at an accelerator current of 15 μA was limited by the power deposited in the uncooled target. The energy of the positrons is concentrated in a small region at about 1 eV and clearly demonstrates the emission of thermal positrons.

  15. Slow positron beam production by a 14 MeV c.w. electron accelerator

    International Nuclear Information System (INIS)

    Begemann, M.; Graeff, G.; Herminghaus, H.; Kalinowsky, H.; Ley, R.

    1982-01-01

    A 14 MeV c.w. electron accelerator is used for pair production in a tungsten target of 0.7 radiation lengths thickness. A small fraction of the positrons is thermalized and diffuses out of the surface of a well annealed tungsten foil coated with MgO which is positioned immediately behind the target. The slow positrons are extracted from the target region and magnetically guided over a distance of 10 m onto a channelplate multiplier at the end of an S-shaped solenoid. The positrons are identified by their annihilation radiation using two Nal-detectors. The intensity of the slow positrons is proportional to the accelerator electron beam current. The maximum intensity of 2.2 x 10 5 slow positrons per second reaching the detector at an accelerator current of 15 μA was limited by the power deposited in the uncooled target. The energy of the positrons is concentrated in a small region at about 1 eV and clearly demonstrates the emission of thermal positrons. (orig.)

  16. Research on cw electron accelerators using room-temperature rf structures: Annual report

    International Nuclear Information System (INIS)

    1986-01-01

    This joint NBS-Los Alamos project of ''Research on CW Electron Accelerators Using Room-Temperature RF Structures'' began seven years ago with the goal of developing a technology base for cw electron accelerators. In this report we describe our progress during FY 1986 and present our plans for completion of the project. First, however, it is appropriate to review the past contributions of the project, describe its status, and indicate its future benefits

  17. Performance of a 967 nm CW diode end-pumped Er:GSGG laser at 2.79 μm

    International Nuclear Information System (INIS)

    Wu, Z H; Sun, D L; Wang, S Z; Luo, J Q; Li, X L; Huang, L; Hu, A L; Tang, Y Q; Guo, Q

    2013-01-01

    We demonstrated a 967 nm diode end-pumped Er:GSGG laser operated at 2.794 μm with spectral width 3.6 nm in the continuous wave (CW) mode. A maximum output power of 440 mW is obtained at an incident pumping power of 3.4 W, which corresponds to an optical-to-optical efficiency of 13% and slope efficiency of 13.2%. The results suggest that a short cavity and efficient cooling setup for the crystal help to improve laser performance. (paper)

  18. CW 50W/M2 = 10.9 diode laser source by spectral beam combining based on a transmission grating.

    Science.gov (United States)

    Zhang, Jun; Peng, Hangyu; Fu, Xihong; Liu, Yun; Qin, Li; Miao, Guoqing; Wang, Lijun

    2013-02-11

    An external cavity structure based on the -1st transmission grating is introduced to spectral beam combining a 970 nm diode laser bar. A CW output power of 50.8 W, an electro-optical conversion efficiency of 45%, a spectral beam combining efficiency of 90.2% and a holistic M(2) value of 10.9 are achieved. This shows a way for a diode laser source with several KW power and diffraction-limited beam quality at the same time.

  19. Forensic Application of FM-CW and Pulse Radar

    Energy Technology Data Exchange (ETDEWEB)

    S. K. Koppenjan; R. S. Freeland; M. L. Miller; R. E. Yoder

    2003-01-01

    Ground-penetrating radar (GPR) technology has supplied vital assistance in criminal investigations. However, law enforcement personnel desire further developments such that the technology is rapidly deployable, and that it provides both a simple user interface and sophisticated target identification. To assist in the development of target identification algorithms, our efforts involve gathering background GPR data for the various site conditions and circumstances that often typify clandestine burials. For this study, forensic anthropologists established shallow-grave plots at The University of Tennessee Anthropological Research Facility (ARF) that are specific to GPR research. These plots contain donated human cadavers lying in various configurations and depths, surrounded by assorted construction material and backfill debris. We scanned the plots using two GPR technologies: (1) a multi-frequency synthetic-aperture FM-CW radar (200-700 MHz) (GPR-X) developed by the U.S. Department of Energy's (DOE) Special Technologies Laboratory (STL), Bechtel Nevada (Koppenjan et al., 2000), and (2) a commercial pulse radar (SIR-20) manufactured by Geophysical Survey Systems, Inc. (400 and 900 MHz)(GSSI). The sweep-frequency data show the large biological mass decomposing within the torso as encircled ''hot spots.'' The 400-MHz pulse radar exhibit major horizontal reflectors above the body, with shadow reflectors (horizontal multiples) occurring beneath the body at 60 cm depth. The 400-MHz antenna was able to discern the grave walls and folded tarp covering the lower body. Under these moist, clay-rich conditions, the 900-MHz antenna was able to penetrate slightly beyond 30 cm beneath the concrete layer. However, neither system was able to penetrate beyond a one meter depth in the moist, clay-rich soil (fine, mixed, thermic Typic Paleudalf). Example scans from each system are provided, along with a discussion of the survey protocol and general performance.

  20. Evaluation of environmental impact from APCA/CW partnership

    International Nuclear Information System (INIS)

    Milmoe, P.H.; Ross, M.

    1999-01-01

    This paper examines the APCA/Climate Wise Partnership and its potential energy and environmental impacts. The authors discuss the issues surrounding greenhouse gas emissions from the production of cement, new and future technologies, and the primary drivers and barriers associated with reducing emissions. The APCA/CW Partner actions and the aggregated impacts of these actions that are undertaken through this partnership are examined. These impacts include cost and energy savings and emission reductions for the current year, and estimated for the year 2000. Comparing these impacts to industrial CO 2 benchmarks indicate the level of effort and what additionally needs to be accomplished. The current results from this partnership indicate that in the remainder of the industry adopts their level of effort, greenhouse gas emissions can be reduced well below the business-as-usual benchmarks. The US cement industry accounts for about 1.5% of US industrial energy use and about 5% of US industrial carbon dioxide (CO 2 ) emissions. In 1997 Climate Wise and the American Portland Cement Alliance (APCA) embarked upon a unique partnership to turn energy efficiency and pollution prevention into a corporate asset. This partnership consists of the 16 APCA member companies, representing nearly 60% of US cement manufacturing capacity. Climate Wise, working with APCA and industry representatives, developed the cement industry Action Plan Software, reporting workbook, and sample Action Plan. Through these tools, continued technical support, and the hard work of the APCA companies, this partnership is showing positive results. Over half of the APCA Climate Wise partners have submitted Action Plans - detailing a comprehensive array of current and future actions to improve energy efficiency and reduce greenhouse gas emissions. These Action Plans have supplied valuable information about how this industry is reducing energy use and greenhouse gas emissions

  1. EBT-S 28-GHz, 200-kW, CW, mixed-mode, quasi-optical plasma heating system

    International Nuclear Information System (INIS)

    White, T.L.; Kimrey, H.D.; Bigelow, T.S.; Bates, D.D.; Eason, H.O.

    1984-07-01

    The ELMO Bumpy Torus-Scale (EBT-S) 28-GHz, 200-kW, cw, plasma heating system consists of a gyrotron oscillator, an oversized waveguide two-bend transmission system, and a quasi-optical mixed-mode microwave distribution manifold that feeds microwave power to the 24 plasma loads of the EBT-S fusion experiment. Balancing power to the 24 loads of the EBT-S fusion experiment. Balancing power to the 24 loads was achieved by adjusting the areas at 24 coupling irises. System performance is easily measured using system calorimetry. The distribution manifold mixed-mode power transmission, reflection, and loss coefficients are 89%, 6%, and 5%, respectively. The overall system efficiency (plasma power/gyrotron power) is 80%, but with some modifications to the distribution manifold we believe the ultimate efficiency can approach 90%. The system reliability is outstanding with a world's record 1 x 10 5 kW h of 28-GHz energy delivered to the EBT-S device with well over 1 x 10 3 operating hours

  2. Fabrication of etched facets and vertical couplers in InP for packaging and on-wafer test

    NARCIS (Netherlands)

    Lemos Alvares Dos Santos, Rui; D'Agostino, D.; Soares, F. M.; Haghighi, H. Rabbani; Williams, K. A.; Leijtens, X. J. M.

    2016-01-01

    In this letter, the fabrication and the characterization of angled and straight etched facets in InP-based technology are reported. In addition, we report on etched facets combined with coupler mirrors for vertical outcoupling, realized with a wet-etching process.

  3. Effective shunt impedance comparison between s-band standing wave accelerators with on-axis and off-axis couplers

    International Nuclear Information System (INIS)

    Schriber, S.O.; Funk, L.W.; Hutcheon, R.M.

    1976-01-01

    The effective shunt impedances of a side-coupled S-band standing wave accelerating structure and a structure employing on-axis couplers have been compared by measuring the energy of accelerated electrons. Criteria for choosing an on-axis coupled structure compared to side-coupled and ''disk and washer'' accelerating structures are given. (author)

  4. Optimizing imbalance and loss in 2 x 2 3dB multimode interference couplers via access waveguide width

    NARCIS (Netherlands)

    Hill, M.T.; Leijtens, X.J.M.; Khoe, G.D.; Smit, M.K.

    2003-01-01

    The imbalance and excess loss in multimode interference couplers with fabrication errors are examined. Remarkably, there exists a number of optimum access waveguide widths which give a minimum imbalance. Furthermore, quite low excess loss can be simultaneously achieved by choosing one particular

  5. 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...

  6. Power

    DEFF Research Database (Denmark)

    Elmholdt, Claus Westergård; Fogsgaard, Morten

    2016-01-01

    and creativity suggests that when managers give people the opportunity to gain power and explicate that there is reason to be more creative, people will show a boost in creative behaviour. Moreover, this process works best in unstable power hierarchies, which implies that power is treated as a negotiable....... It is thus a central point that power is not necessarily something that breaks down and represses. On the contrary, an explicit focus on the dynamics of power in relation to creativity can be productive for the organisation. Our main focus is to elaborate the implications of this for practice and theory...

  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. High-power Yb-doped continuous-wave and pulsed fibre lasers

    Indian Academy of Sciences (India)

    2014-01-05

    Jan 5, 2014 ... In this article, a review of Yb-doped CW and pulsed fibre lasers along with our study on self-pulsing dynamics in CW fibre lasers to find its role in high-power fibre laser development and the physical ... Solid State Laser Division, Raja Ramanna Centre for Advanced Technology, Indore 452 013, India ...

  9. Influence of the oxidiser gas composition on the overtone generation efficiency of a supersonic cw chemical HF laser

    International Nuclear Information System (INIS)

    Konkin, S V; Fedorov, Igor' A; Rebone, Vitalii K; Rotinyan, Mikhail A; Tret'yakov, Nikolai E; Galaev, I I; Moroz, M V; Tomashevich, N N

    1998-01-01

    An experimental investigation was made of the influence of the chemical composition of the oxidiser gas in an atomic-fluorine generator on the efficiency of generation of radiation representing the first overtone of the HF molecule in a self-contained supersonic cw chemical HF laser with the active medium 70 cm long. The optimal chemical composition was different for the fundamental and overtone transitions. A specific output energy of 84 J g -1 at a specific mass flow rate of 0.13 g s -1 cm -2 through the nozzle array was achieved by optimisation of a linear three-mirror optical cavity at the 1.33 - 1.35 μm wavelengths. The overtone radiation power generated in the whole of the active medium was 7.5 kW, corresponding to a 41% efficiency of energy conversion to an overtone. (lasers, active media)

  10. Analytical Study on Propagation Dynamics of Optical Beam in Parity-Time Symmetric Optical Couplers

    International Nuclear Information System (INIS)

    Zhou Zheng; Zhang Li-Juan; Zhu Bo

    2015-01-01

    We present exact analytical solutions to parity-time (PT) symmetric optical system describing light transport in PT-symmetric optical couplers. We show that light intensity oscillates periodically between two waveguides for unbroken PT-symmetric phase, whereas light always leaves the system from the waveguide experiencing gain when light is initially input at either waveguide experiencing gain or waveguide experiencing loss for broken PT-symmetric phase. These analytical results agree with the recent experimental observation reported by Rüter et al. [Nat. Phys. 6 (2010) 192]. Besides, we present a scheme for manipulating PT symmetry by applying a periodic modulation. Our results provide an efficient way to control light propagation in periodically modulated PT-symmetric system by tuning the modulation amplitude and frequency. (paper)

  11. The Design of a Five-Cell Superconducting RF Module with a PBG Coupler Cell

    International Nuclear Information System (INIS)

    Arsenyev, Sergey A.; Simakov, Evgenya I.

    2012-01-01

    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.

  12. Highly sensitive magnetic field sensor based on microfiber coupler with magnetic fluid

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Longfeng; Pu, Shengli, E-mail: shlpu@usst.edu.cn; Tang, Jiali [College of Science, University of Shanghai for Science and Technology, Shanghai 200093 (China); Zeng, Xianglong [2Key Laboratory of Specialty Fiber Optics and Optical Access Network, Shanghai University, Shanghai 200072 (China); Lahoubi, Mahieddine [Department of Physics, Faculty of Sciences, Laboratory L.P.S., Badji Mokhtar-Annaba University, P. O. Box 12, 23000 Annaba (Algeria)

    2015-05-11

    A kind of magnetic field sensor using a microfiber coupler (MFC) surrounded with magnetic fluid (MF) is proposed and experimentally demonstrated. As the MFC is strongly sensitive to the surrounding refractive index (RI) and MF's RI is sensitive to magnetic field, the magnetic field sensing function of the proposed structure is realized. Interrogation of magnetic field strength is achieved by measuring the dip wavelength shift and transmission loss change of the transmission spectrum. The experimental results show that the sensitivity of the sensor is wavelength-dependent. The maximum sensitivity of 191.8 pm/Oe is achieved at wavelength of around 1537 nm in this work. In addition, a sensitivity of −0.037 dB/Oe is achieved by monitoring variation of the fringe visibility. These suggest the potential applications of the proposed structure in tunable all-in-fiber photonic devices such as magneto-optical modulator, filter, and sensing.

  13. Highly sensitive magnetic field sensor based on microfiber coupler with magnetic fluid

    International Nuclear Information System (INIS)

    Luo, Longfeng; Pu, Shengli; Tang, Jiali; Zeng, Xianglong; Lahoubi, Mahieddine

    2015-01-01

    A kind of magnetic field sensor using a microfiber coupler (MFC) surrounded with magnetic fluid (MF) is proposed and experimentally demonstrated. As the MFC is strongly sensitive to the surrounding refractive index (RI) and MF's RI is sensitive to magnetic field, the magnetic field sensing function of the proposed structure is realized. Interrogation of magnetic field strength is achieved by measuring the dip wavelength shift and transmission loss change of the transmission spectrum. The experimental results show that the sensitivity of the sensor is wavelength-dependent. The maximum sensitivity of 191.8 pm/Oe is achieved at wavelength of around 1537 nm in this work. In addition, a sensitivity of −0.037 dB/Oe is achieved by monitoring variation of the fringe visibility. These suggest the potential applications of the proposed structure in tunable all-in-fiber photonic devices such as magneto-optical modulator, filter, and sensing

  14. Monolithic optofluidic mode coupler for broadband thermo- and piezo-optical characterization of liquids.

    Science.gov (United States)

    Pumpe, Sebastian; Chemnitz, Mario; Kobelke, Jens; Schmidt, Markus A

    2017-09-18

    We present a monolithic fiber device that enables investigation of the thermo- and piezo-optical properties of liquids using straightforward broadband transmission measurements. The device is a directional mode coupler consisting of a multi-mode liquid core and a single-mode glass core with pronounced coupling resonances whose wavelength strongly depend on the operation temperature. We demonstrated the functionality and flexibility of our device for carbon disulfide, extending the current knowledge of the thermo-optic coefficient by 200 nm at 20 °C and uniquely for high temperatures. Moreover, our device allows measuring the piezo-optic coefficient of carbon disulfide, confirming results first obtained by Röntgen in 1891. Finally, we applied our approach to obtain the dispersion of the thermo-optic coefficients of benzene and tetrachloroethylene between 450 and 800 nm, whereas no data was available for the latter so far.

  15. Broad-band anti-reflection coupler for a : Si thin-film solar cell

    International Nuclear Information System (INIS)

    Lo, S.-S.; Chen, C.-C.; Garwe, Frank; Pertch, Thomas

    2007-01-01

    This work numerically demonstrates a new anti-reflection coupler (ARC) with high coupling efficiency in a Si substrate solar cell. The ARC in which the grating is integrated on a glass encapsulation and a three-layer impedance match layer is proposed. A coupling efficiency of 90% is obtained at wavelengths between 350 and 1200 nm in the TE and TM modes when the incident angle is less than 30 0 . In comparison with a 1μm absorber layer, the integrated absorption of an a-Si thin-film solar cell without a new ARC is doubled, at long wavelengths (750 nm ≤ λ ≤ 1200 nm), as calculated by FDTD method

  16. HOM power in FCC-ee cavities

    CERN Document Server

    Karpov, Ivan; Chapochnikova, Elena

    2018-01-01

    This Note summarizes the results of the power loss calculations for FCC-ee machines with 400.79 MHz cavity options. The requirements for the single-cell cavity design and for the operation with beam are obtained from the results for the high-current FCC-ee machine (Z). For other machines the power loss is sufficiently low and can be absorbed and extracted by foreseen HOM couplers.

  17. 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.

  18. A compact, CW mid-infrared intra-cavity Nd:Lu0.5Y0.5VO4∖KTA-OPO at 3.5 μm

    International Nuclear Information System (INIS)

    Duan, Y M; Zhu, H Y; Feng, Z R; Xu, C W; Tang, D Y; Zhang, J; Wang, H Y

    2013-01-01

    We report a continuous-wave (CW) KTA (KTiOAsO 4 )-OPO (optical parametric oscillator) with a compact linear cavity utilizing an LD pumped mixed crystal Nd:Lu 0.5 Y 0.5 VO 4 laser as the pump source for the first time. A singly resonant oscillator with low signal light loss was designed to reduce the OPO’s threshold. Maximum output powers of 630 mW at 3475 nm and 190 mW at 1536 nm were obtained at a pump power of 13.2 W. A total conversion efficiency of 6.2% was achieved with respect to the incident diode pump power. The performance of this work demonstrates that a CW KTA-OPO derived by an LD pumped Nd 3+ doped solid laser can also produce efficient mid-infrared light. (letter)

  19. Investigation on Mechanical Properties and Microstructure of Hydroxyapatite-SiCw Composite Bioceramics

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Hydroxyapatite-SiCw composite micropowder was synthesized using in-situ composite method,and hydroxyapatite-SiCw composite bioceramics with different content of SiCw were produced by hot pressing sintering method. The microstructures of the materials were analyzed by SEM, and the relative density, bending strength and fracture toughness of the materials were tested. The results show that the mechanical properties of composite material are best when the whisker content is 20-23.7% . The mechanical properties of the material are the best when the tensile stress acted on the composite material is parallel with the hot pressing plane, and they are the worst when the tensile stress acted on the composite material is normal to the hot pressing plane.

  20. Crystal growth, spectroscopic and CW laser properties of Nd0.03Lu2.871Gd0.099Al5O12 crystal

    Science.gov (United States)

    Di, J. Q.; Xu, X. D.; Cheng, S. S.; Li, D. Z.; Zhou, D. H.; Wu, F.; Zhao, Z. W.; Xu, J.

    2011-11-01

    Nd0.03Lu2.871Gd0.099Al5O12 (Nd:LuGdAG) crystal was grown by the Czochralski method. The absorption, fluorescence spectra and fluorescence lifetime of Nd:LuGdAG crystal at room temperature were investigated for the first time. We reported the continuous-wave (CW) Nd:LuGdAG laser operation under diode pumping. Output power of 1.43 W at 1064 nm was achieved with a slope efficiency of 34.1%. All the results show that Nd:LuGdAG crystal is a promising laser material.

  1. Polarization-dependent Character of 1x3 Beam Splitter Using Self-Imaging Phenomena in Air-Slab PhCW

    DEFF Research Database (Denmark)

    Zhang, Min; Malureanu, Radu; Kristensen, Martin

    2010-01-01

    A 1x3 beam splitter in PhCWs using multi-mode interference (MMI) based on self-imaging principle is investigated. The 1x3 splitter is polarization-dependent. The total TE-polarized transmission of the 1x3 splitter is almost equal to the corresponding length of W1 PhCW. The TE-polarized input power...... is distributed equally be-tween the output ports within 1dB from 1541nm to 1552nm....

  2. Design, construction and tuning of S-band coupler for electron linear accelerator of institute for research in fundamental sciences (IPM E-linac)

    International Nuclear Information System (INIS)

    Ghasemi, F.; Abbasi Davani, F.; Lamehi Rachti, M.; Shaker, H.; Ahmadiannamin, S.

    2015-01-01

    Design and construction of an electron linear accelerator by Institute for Research in Fundamental Science (IPM) is considered as Iran’s first attempt to construct such an accelerator. In order to design a linear accelerating tube, after defining the accelerating tube and buncher geometries, RF input and output couplers must be designed. In this article, firstly, a brief report on the specifications of an S-band electron linear accelerator which is in progress in the school of particles and accelerators is presented and then, the design process and construction reports of the couplers required for this accelerator are described. Through performing necessary calculations and tuning the coupling factor and resonant frequency, couplers with desired specification have been fabricated by shrinking method. The final obtained coupling factor and resonant frequency have been respectively 1.05 and 2997 MHz for the first coupler, and 0.98 and 2996.9 MHz for the second one that are close to calculation results

  3. Modulated Sine Waves for Differential Absorption Measurements Using a CW Laser System

    Science.gov (United States)

    Campbell, Joel F. (Inventor); Lin, Bing (Inventor); Nehrir, Amin R. (Inventor)

    2015-01-01

    A continuous wave Light Detection and Ranging (CW LiDAR) system utilizes two or more laser frequencies and time or range shifted pseudorandom noise (PN) codes to discriminate between the laser frequencies. The performance of these codes can be improved by subtracting out the bias before processing. The CW LiDAR system may be mounted to an artificial satellite orbiting the earth, and the relative strength of the return signal for each frequency can be utilized to determine the concentration of selected gases or other substances in the atmosphere.

  4. Ultra-Broadband Silicon-Wire Polarization Beam Combiner/Splitter Based on a Wavelength Insensitive Coupler With a Point-Symmetrical Configuration

    OpenAIRE

    Uematsu, Takui; Kitayama, Tetsuya; Ishizaka, Yuhei; Saitoh, Kunimasa

    2014-01-01

    An ultrabroadband silicon wire polarization beam combiner/splitter (PBCS) based on a wavelength-insensitive coupler is proposed. The proposed PBCS consists of three identical directional couplers and two identical delay lines. We design the PBCS using the 3-D finite element method. Numerical simulations show that the proposed PBCS can achieve the transmittance of more than 90% over a wide wavelength range from 1450 to 1650 nm for both TE and TM polarized modes.

  5. Cavity-enhanced resonant photoacoustic spectroscopy with optical feedback cw diode lasers: A novel technique for ultratrace gas analysis and high-resolution spectroscopy.

    Science.gov (United States)

    Hippler, Michael; Mohr, Christian; Keen, Katherine A; McNaghten, Edward D

    2010-07-28

    Cavity-enhanced resonant photoacoustic spectroscopy with optical feedback cw diode lasers (OF-CERPAS) is introduced as a novel technique for ultratrace gas analysis and high-resolution spectroscopy. In the scheme, a single-mode cw diode laser (3 mW, 635 nm) is coupled into a high-finesse linear cavity and stabilized to the cavity by optical feedback. Inside the cavity, a build-up of laser power to at least 2.5 W occurs. Absorbing gas phase species inside the cavity are detected with high sensitivity by the photoacoustic effect using a microphone embedded in the cavity. To increase sensitivity further, coupling into the cavity is modulated at a frequency corresponding to a longitudinal resonance of an organ pipe acoustic resonator (f=1.35 kHz and Q approximately 10). The technique has been characterized by measuring very weak water overtone transitions near 635 nm. Normalized noise-equivalent absorption coefficients are determined as alpha approximately 4.4x10(-9) cm(-1) s(1/2) (1 s integration time) and 2.6x10(-11) cm(-1) s(1/2) W (1 s integration time and 1 W laser power). These sensitivities compare favorably with existing state-of-the-art techniques. As an advantage, OF-CERPAS is a "zero-background" method which increases selectivity and sensitivity, and its sensitivity scales with laser power.

  6. High power tests of dressed supconducting 1.3 GHz RF cavities

    Energy Technology Data Exchange (ETDEWEB)

    Hocker, A.; Harms, E.R.; Lunin, A.; Sukhanov, A.; /Fermilab

    2011-03-01

    A single-cavity test cryostat is used to conduct pulsed high power RF tests of superconducting 1.3 GHz RF cavities at 2 K. The cavities under test are welded inside individual helium vessels and are outfitted ('dressed') with a fundamental power coupler, higher-order mode couplers, magnetic shielding, a blade tuner, and piezoelectric tuners. The cavity performance is evaluated in terms of accelerating gradient, unloaded quality factor, and field emission, and the functionality of the auxiliary components is verified. Test results from the first set of dressed cavities are presented here.

  7. VVER-440 control rod follower induced local power peaking computational benchmark: MCNP and KARATE solutions

    International Nuclear Information System (INIS)

    Hegyi, G.; Hordosy, G.; Kereszturi, A.; Maraczy, C.; Temesvari, E.

    2009-01-01

    In this paper the linear pin power calculation in the KARATE-440 code system are presented. The calculation results show that: 1) The coupler mathematical benchmark was solved by the KARATE code system using the same methods and approximations as in case of NPP applications. 2) Without Hf plate in the fuel pin row next to the problematic coupler section pronounced local power peak arises. 4) Though the underprediction of the peak by KARATE-SADR is 4%, it is in accordance with the applied uncertainty of KARATE-SADR. 5) The application of Hf plate solves the problem.

  8. Design of a hybrid silicon-plasmonic co-propagating coupler operating close to coherent perfect absorption

    Energy Technology Data Exchange (ETDEWEB)

    Zanotto, Simone; Melloni, Andrea [Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy)

    2016-04-28

    By hybrid integration of plasmonic and dielectric waveguide concepts, it is shown that nearly perfect coherent absorption can be achieved in a co-propagating coupler geometry. First, the operating principle of the proposed device is detailed in the context of a more general 2 × 2 lossy coupler formalism. Then, it is shown how to tune the device in a wide region of possible working points, its broadband operation, and the tolerance to fabrication uncertainties. Finally, a complete picture of the electromagnetic modes inside the hybrid structure is analyzed, shining light onto the potentials which the proposed device holds in view of classical and quantum signal processing, nonlinear optics, polarization control, and sensing.

  9. Femtosecond laser inscription of asymmetric directional couplers for in-fiber optical taps and fiber cladding photonics.

    Science.gov (United States)

    Grenier, Jason R; Fernandes, Luís A; Herman, Peter R

    2015-06-29

    Precise alignment of femtosecond laser tracks in standard single mode optical fiber is shown to enable controllable optical tapping of the fiber core waveguide light with fiber cladding photonic circuits. Asymmetric directional couplers are presented with tunable coupling ratios up to 62% and bandwidths up to 300 nm at telecommunication wavelengths. Real-time fiber monitoring during laser writing permitted a means of controlling the coupler length to compensate for micron-scale alignment errors and to facilitate tailored design of coupling ratio, spectral bandwidth and polarization properties. Laser induced waveguide birefringence was harnessed for polarization dependent coupling that led to the formation of in-fiber polarization-selective taps with 32 dB extinction ratio. This technology enables the interconnection of light propagating in pre-existing waveguides with laser-formed devices, thereby opening a new practical direction for the three-dimensional integration of optical devices in the cladding of optical fibers and planar lightwave circuits.

  10. High average power 1314 nm Nd:YLF laser, passively Q-switched with V:YAG

    CSIR Research Space (South Africa)

    Botha, RC

    2013-03-01

    Full Text Available A 1314 nm Nd:YLF laser was designed and operated both CW and passively Q-switched. Maximum CW output of 10.4 W resulted from 45.2 Wof incident pump power. Passive Q-switching was obtained by inserting a V:YAG saturable absorber in the cavity...

  11. Monolithically integrated fiber-to-the-home diplexers and triplexers using a bilevel etched 2 x 2 optical coupler.

    Science.gov (United States)

    Zhang, Li; Wang, Lei; He, Jian-Jun

    2009-09-01

    A novel design of monolithically integrated diplexers and triplexers for fiber-to-the-home applications is presented. A bilevel etched asymmetrical 2 x 2 optical coupler is analyzed for efficient couplings of both upstream and downstream signals. The design of the diplexer is extended to a triplexer by adding an etched diffraction grating as an additional downstream demultiplexing element. The total size of the integrated diplexer and triplexer is smaller than 500 microm x 500 microm.

  12. Highly efficient F-19 heteronuclear decoupling in solid-state NMR spectroscopy using supercycled refocused-CW irradiation

    DEFF Research Database (Denmark)

    Equbal, Asif; Basse, Kristoffer; Nielsen, Niels Christian

    2016-01-01

    We present heteronuclear F-19 refocused CW (rCW) decoupling pulse sequences for solid-state magic-angle- spinning NMR applications. The decoupling sequences have been designed specifically to ensure suppression of the pertinent C-13-F-19 dipolar coupling interactions while simultaneously suppress...

  13. High-directionality fiber-chip grating coupler with interleaved trenches and subwavelength index-matching structure.

    Science.gov (United States)

    Benedikovic, Daniel; Alonso-Ramos, Carlos; Cheben, Pavel; Schmid, Jens H; Wang, Shurui; Xu, Dan-Xia; Lapointe, Jean; Janz, Siegfried; Halir, Robert; Ortega-Moñux, Alejandro; Wangüemert-Pérez, J Gonzalo; Molina-Fernández, Iñigo; Fédéli, Jean-Marc; Vivien, Laurent; Dado, Milan

    2015-09-15

    We present the first experimental demonstration of a new fiber-chip grating coupler concept that exploits the blazing effect by interleaving the standard full (220 nm) and shallow etch (70 nm) trenches in a 220 nm thick silicon layer. The high directionality is obtained by controlling the separation between the deep and shallow trenches to achieve constructive interference in the upward direction and destructive interference toward the silicon substrate. Utilizing this concept, the grating directionality can be maximized independent of the bottom oxide thickness. The coupler also includes a subwavelength-engineered index-matching region, designed to reduce the reflectivity at the interface between the injection waveguide and the grating. We report a measured fiber-chip coupling efficiency of -1.3  dB, the highest coupling efficiency achieved to date for a surface grating coupler in a 220 nm silicon-on-insulator platform fabricated in a conventional dual-etch process without high-index overlays or bottom mirrors.

  14. L-shaped fiber-chip grating couplers with high directionality and low reflectivity fabricated with deep-UV lithography.

    Science.gov (United States)

    Benedikovic, Daniel; Alonso-Ramos, Carlos; Pérez-Galacho, Diego; Guerber, Sylvain; Vakarin, Vladyslav; Marcaud, Guillaume; Le Roux, Xavier; Cassan, Eric; Marris-Morini, Delphine; Cheben, Pavel; Boeuf, Frédéric; Baudot, Charles; Vivien, Laurent

    2017-09-01

    Grating couplers enable position-friendly interfacing of silicon chips by optical fibers. The conventional coupler designs call upon comparatively complex architectures to afford efficient light coupling to sub-micron silicon-on-insulator (SOI) waveguides. Conversely, the blazing effect in double-etched gratings provides high coupling efficiency with reduced fabrication intricacy. In this Letter, we demonstrate for the first time, to the best of our knowledge, the realization of an ultra-directional L-shaped grating coupler, seamlessly fabricated by using 193 nm deep-ultraviolet (deep-UV) lithography. We also include a subwavelength index engineered waveguide-to-grating transition that provides an eight-fold reduction of the grating reflectivity, down to 1% (-20  dB). A measured coupling efficiency of -2.7  dB (54%) is achieved, with a bandwidth of 62 nm. These results open promising prospects for the implementation of efficient, robust, and cost-effective coupling interfaces for sub-micrometric SOI waveguides, as desired for large-volume applications in silicon photonics.

  15. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Characteristics of the evolution of a plasma formed by cw and pulse-periodic CO2 laser radiation in various gases

    Science.gov (United States)

    Kanevskiĭ, M. F.; Stepanova, M. A.

    1990-06-01

    An investigation was made of the interaction between high-power cw and pulse-periodic CO2 laser radiation and a low-threshold optical breakdown plasma near a metal surface. Characteristics of the breakdown plasma were studied as a function of the experimental conditions. A qualitative analysis was made of the results using a simple one-dimensional model for laser combustion waves.

  16. Optical and near-infrared study of the AM Herculis-type binary CW 1103 + 254

    Energy Technology Data Exchange (ETDEWEB)

    Bailey, J [Anglo-Australian Observatory, Epping (Australia); Watts, D J [Tasmania Univ., Sandy Bay (Australia). Dept. of Physics; Sherrington, M R [Leicester Univ. (UK). Dept. of Astronomy

    1985-07-15

    The AM Herculis-type binary CW 1103+254 has been observed using optical and near-infrared photometry and polarimetry, and optical spectroscopy and spectropolarimetry. It is found that from such a set of observations it is relatively easy to distinguish all the main components of the system.

  17. Design of 57.5 MHz CW RFQ structure for the Rare Isotope ...

    Indian Academy of Sciences (India)

    The Rare Isotope Accelerator (RIA) facility includes a driver LINAC for production of 400 kW CW heavy-ion beams. The initial acceleration of heavy ions delivered from an ECR ion source can be effectively performed by a 57.5 MHz 4 m long RFQ. The principal specifications of the RFQ are: (1) formation of extremely low ...

  18. Red-light-emitting laser diodes operating CW at room temperature

    Science.gov (United States)

    Kressel, H.; Hawrylo, F. Z.

    1976-01-01

    Heterojunction laser diodes of AlGaAs have been prepared with threshold current densities substantially below those previously achieved at room temperature in the 7200-8000-A spectral range. These devices operate continuously with simple oxide-isolated stripe contacts to 7400 A, which extends CW operation into the visible (red) portion of the spectrum.

  19. 1 CW green self-frequency-doubled Yb:YAl3(BO3)4 laser

    International Nuclear Information System (INIS)

    Dekker, P.; Dawes, J.; Wang, P.; Piper, J.

    2000-01-01

    Full text: We report 1.1 W continuous wave (CW) green output from a 977nm diode-end-pumped self-frequency-doubled Yb:YAB laser, with a diode-to-green optical conversion efficiency of 10%. Wavelength tunability from 513-546nm has been demonstrated

  20. Canvas supports and grounds in paintings by C.W. Eckersberg

    DEFF Research Database (Denmark)

    Filtenborg, Troels; Andersen, Cecil Krarup

    2017-01-01

    The supports and grounds in 43 paintings on canvas by C.W. Eckersberg, dating from throughout his career, were investigated by visual examination, X-radiography, computer assisted automated thread counting and weave mapping, as well as by cross section analysis. The analytical data were complemen...