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Development of a 500-MHz waveguide directional coupler with high directivity for HEPS

Radiation Detection Technology and Methods 2022年第3期6卷 323-329页

作者： Yuanli Luo Jian Li Pei Zhang Qiang Ma Haiying Lin Tongming Huang Fanbo Meng Facheng Zhao Ziwei Deng Institute of High Energy Physics(IHEP) Chinese Academy of Sciences(CAS)Beijing 100049China School of Nuclear Sciences and Technology University of Chinese Academy of SciencesBeijing 100049China Key Laboratory of Particle Acceleration Physics and Technology IHEPCASBeijing 100049China

Purpose In order to achieve a high-precision measurement of the incident and the reﬂected power,a WR1800 rectangular waveguide directional coupler with high directivity and high power level has been in-house developed.Multiple couplers will be installed in the 500-MHz high-power radio-frequency transmission lines delivering 200-kW continuous-wave power for the High Energy Photon Source(HEPS).Methods The directional coupler adopts the design scheme of primary and secondary transmission lines and coaxial coupling-head structure.The shape and dimensional parameters of the coupling head were carefully optimized by using microwave simulation codes.An optimum directivity of 64 dB was achieved in simulations.Results and conclusions A prototype coupler was subsequently manufactured,and its directivity was measured to be 48.2 dB following a rigorous calibration procedure,largely exceeding the design goal and the commercial product.The coupler was then connected to an existing 500-MHz klystron system,and a high-power test with short-circuit termination was conducted.The high directivity of the coupler was conﬁrmed up to 200 kW.During the 6 hours of power aging with continuous-wave 200 kW in a standing-wave setup,no performance degradation was observed on the coupler.The coupler temperature was measured to be 20◦C above the ambient environment.The design requirements were comfortably fulﬁlled.These constitute theﬁrst in-house development of a large-size waveguide directional coupler with high directivity and high power level for HEPS.The design,fabrication,and performance tests of the directional coupler are presented.

关键词： directional coupler High directivity Simulation optimization High-power RF High Energy Photon Source

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RF design and test of a high-directivity high-power waveguide directional coupler for the HEPS

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Radiation Detection Technology and Methods 2022年第2期6卷 137-142页

作者： Xiang He Jing-Ru Zhang Jing-Dong Liu Hua Shi Bing-Lin Deng Xu-Jian Wang Sheng-Chang Wang Nan Gan Pi-Long Tian Key Laboratory of Particle Acceleration Physics and Technology Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China

Purpose A novel high-directivity high-power waveguide directional coupler(DC)working at 2998.8 MHz is developed for the High Energy Photon Source.It can help the phase control system to obtain a very accurate microwave signal,which is very important to minimize the beam emittance.Methods The novel reversely placed T-type coupling piece helps to obtain a high directivity.The N-type high-vacuum feedthroughs for vacuum sealing instead of the traditional ceramic plate is beneficial to holding a higher peak power.The simulation and the high-power commissioning are accomplished in the Institute of High Energy Physics(IHEP),while the fabrication and the low-power test are conducted in cooperation with the manufacturer.Results Both the single-coupler and the dual-coupler DCs are developed with a directivity of more than 35 dB while keeping the coupling factor within 60±0.5 dB.Finally,69.4%of all the fifty-two mass produced DCs have got a directivity of more than 40 dB.Conclusion:The mature manufacturing process for mass production is obtained.The novel high-directivity high-power waveguide DC can be mass produced with an actually internationally leading performance.

关键词： HEPS directional coupler High directivity High power Mass production

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Design of a High Power directional coupler with High Directivity Used in the LHCD Launcher for EAST

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Plasma Science and Technology 2009年第6期11卷 739-743页

作者：张长虹刘甫坤杨津甫赵洪亮 Institute of Plasma Physics Chinese Academy of Sciences

A high power waveguide directional coupler was designed to measure the transmitted power and reflected power in the 4.6 GHz LHCD （lower hybrid current drive） launcher for the EAST tokamak. The design principle of the coupler is assessed. Further analysis is performed by CST （computer simulating test） and Ansoft HFSS （high frequency structure simulator） software and the optimal structural parameter is obtained. In addition, finite element code ANSYS is used to determine the temperature distribution in the coupler conductively cooled by forced water. The test results of a directional coupler manufactured according to the design are close to what is expected.

关键词： directional coupler directivity thermal analysis test

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Design of a compact polarization beam splitter based on a deformed photonic crystal directional coupler

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Chinese Physics B 2008年第7期17卷 2553-2556页

作者：任刚郑婉华王科杜晓宇邢名欣陈良惠 Nano-Optoelectronic Laboratory Institute of SemiconductorsChinese Academy of Sciences

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 waveguldes is strongly enhanced by introducing elliptical airholes, which reduce the device length to less than 18.Sttm. A finite-difference tlme-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.

关键词： photonic crystal polarization beam splitter directional coupler

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Nonideal effects in quantum field-effect directional coupler

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Chinese Physics B 2006年第10期15卷 2415-2421页

作者：谢月娥颜晓红陈元平 Institute of Modern Physics and Department of Physics Xiangtan University Xiangtan 411105 China College of Science Nanfing University of Aeronautics and Astronautics Nanjing 210016 China

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

关键词： nonideal effects directional coupler Green function

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An Ultra-Compact Broadband Polarizing Beam Splitter Utilizing Hybrid Plasmonic Waveguide

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China Communications 2023年第6期20卷 49-59页

作者： Li Zhang Jiaqi Liu Can Pan Yatao Yang College of Electronics and Information Engineering Shenzhen UniversityShenzhen 518000China

Polarizing beam splitter has rather significant applications in polarization diversity circuits and polarization multiplexing systems.In this paper,we present an asymmetric polarizing beam splitter utilizing hybrid plasmonic waveguide.The special hybrid structure with a hybrid waveguide and a dielectric waveguide can limit the energy of TE and TM modes to a different layer.Therefore,we can achieve beam splitting by adjusting the corresponding parameters of the two waveguides.First,we studied the influences of different structure parameters on the real part of the effective mode refractive index of the two waveguides,and obtained a set of parameters that satisfy the condition of strong coupling of TM mode and weak coupling of TE mode.Then,the performance of our proposed polarizing beam splitter is evaluated numerically.The length of the coupling section is only 4.1μm,and the propagation loss of TM and TE modes is 0.0025 d B/μm and 0.0031 d B/μm respectively.Additionally,the extinction ratios of TM and TE modes are 10.62 d B and 12.55 d B,respectively.Particularly,the proposed device has excellent wavelength insensitivity.Over the entire C-band,the fluctuation of the whole normalized output power is less than 0.03.In short,our proposed asymmetric polarizing beam splitter features ultra-compactness,low propagation loss,and broad bandwidth,which would provide promising applications in polarization multiplexing system and polarization diversity circuits relevant to optical interconnection.

关键词： polarizing beam splitter hybrid plasmonic waveguide directional coupler polarization multiplexing systems

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A design method for high fabrication tolerance integrated optical mode multiplexer

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Science China(Information Sciences) 2020年第6期63卷 184-194页

作者： Bitao SHEN Haowen SHU Linjie ZHOU Xingjun WANG State Key Laboratory on Advanced Optical Communication Systems and Networks Department of ElectronicsSchool of Electronics Engineering and Computer Science Peking University State Key Laboratory of Advanced Optical Communication Systems and Networks Department of Electronic Engineering Shanghai Jiao Tong University Nano-optoelectronics Frontier Center of Ministry of Education Peking University

The tapered asymmetric directional coupler has the potential to realize high fabrication tolerance and high transmission efficiency on-chip mode multiplexer. However, the geometry parameter selection of tapered structure remains empirical. In this paper, we propose a design method for the tapered structure based on genetic algorithm. Combined with the adjusted coupling equations and interpolation method, lowtime-cost optimization can be realized. Three mode multiplexers(TE0&TE1, TE0&TE2 and TE0&TE5)are designed by our method. According to simulation results, the insertion loss of the designed devices is lower than 1.8 dB and the crosstalk is lower than-15 dB when the fabrication error is within required range(±10 nm for TE0&TE2 and TE0&TE5, and ±20 nm for TE0&TE1) in the bandwidth of 1.5–1.6 μm. In addition, the entire optimization process takes only 2 h for each device, which is around the time cost of a single 3 D simulation.

关键词： mode multiplexer directional coupler taper structure coupled-mode theory genetic algorithm

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Silicon-based on-chip diplexing/triplexing technologies and devices

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Science China(Information Sciences) 2018年第8期61卷 18-32页

作者： Yaocheng SHI Jingye CHEN Hongnan XU Centre for Optical and Electromagnetic Research State Key Laboratory of Modern Optical InstrumentationZhejiang University

Wavelength-division-multiplexing(WDM) transceiver filters are one of the most essential components for realizing the fiber-to-the-home(FTTH) networks. In recent years, silicon photonics have provided a very attractive platform to build ultra-compact photonic integrated devices with CMOS-compatible processes. In this review, we focus on the recent progresses on diplexers/triplexers based on multimode interference couplers(MMI), and directional couplers(DC). The polarization-insensitive devices are also discussed.

关键词： wavelength division multiplexer multimode interference coupler directional coupler fiber-tothe-home silicon waveguide

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Highly sensitive and fast response strain sensor based on evanescently coupled micro/nanofibers

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Opto-Electronic Advances 2022年第9期5卷 34-42页

作者： Wen Yu Ni Yao Jing Pan Wei Fang Xiong Li Limin Tong Lei Zhang State Key Laboratory of Modern Optical Instrumentation College of Optical Science and EngineeringZhejiang UniversityHangzhou 310027China Research Center for Intelligent Sensing Zhejiang LabHangzhou 311121China Tencent Robotics X Lab Tencent Technology(Shenzhen)Co.LtdShenzhen 518054China

Flexible strain sensors play an important role in electronic skins,wearable medical devices,and advanced robots.Herein,a highly sensitive and fast response optical strain sensor with two evanescently coupled optical micro/nanofibers(MNFs)embedded in a polydimethylsiloxane(PDMS)film is proposed.The strain sensor exhibits a gauge factor as high as 64.5 for strain≤0.5%and a strain resolution of 0.0012%which corresponds to elongation of 120 nm on a 1 cm long device.As a proof-of-concept,highly sensitive fingertip pulse measurement is realized.The properties of fast temporal frequency response up to 30 kHz and a pressure sensitivity of 102 kPa^(−1) enable the sensor for sound detection.Such versatile sensor could be of great use in physiological signal monitoring,voice recognition and micro-displacement detection.

关键词： optical micro/nanofiber strain sensor pressure sensor micro-displacement directional coupler

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Review of photonic Hilbert transformers

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Frontiers of Optoelectronics 2013年第1期6卷 78-88页

作者： Chaotan SIMA Optoelectronics Research Centre University of Southampton Southampton SOl 7 1B J UK

This paper reviews the demonstrations of photonic Hilbert transformers(PHTs), describing their progress and recent developments. The physical operating principles of PHTs including fractional Hilbert transformers are discussed, together with device applications in all-optical signal processing. Versatile approaches to realize PHTs are discussed, e.g., discrete free space optics, fiber-based schemes and integrated planar geometry. The numerical designs and experimental performances of these PHTs are analyzed in terms of spectral quality, operating bandwidth, system integration, and mechanical and thermal stability. Recent developments of the monolithically integrated photonic Hilbert transform (HT) devices include directional couplers and planar Bragg gratings which allow all-optical single-sideband (SSB) suppression and sideband switching.

关键词： photonic Hilbert transformer (PHT) Bragg reflectors direct UV writing all-optical signal processing Bragg reflectors Single sideband Hilbert Transformer directional coupler Raster processing photonic Optical signal processing

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