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Polarization-entangled photon pairs with factorable spectra engineered by using an uneven four-stage nonlinear interferometer

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Chinese Optics Letters 2024年第5期22卷 106-110页

作者：崔亮陈浩然李嘉敏李小英 College of precision instrument and opto-electronics engineering Key Laboratory of Opto-Electronics Information TechnologyMinistry of EducationTianjin UniversityTianjin 300072China school of Physics Taiyuan University of TechnologyTaiyuan 030000China

We report the generation of polarization-entangled photon pairs in the 1550 nm band by pumping an uneven nonlinear interferometer loop with two orthogonally polarized counterpropagating pump *** uneven nonlinear interferometer,providing a more ideal interference pattern due to the elimination of secondary maxima,consists of four pieces of dispersion-shifted fibers sandwiched with three pieces of standard single-mode fibers,and the lengths of the nonlinear fibers follow the binomial *** mode number of the photon pairs deduced from the measured joint spectrum is∼*** collection efficiency of the photon pairs is found to be∼94%(after background noise correction).The directly measured visibility of two-photon interference of the polarization-entangled photon pairs is∼92%,while no interference is observed in the direct detection of either the signal or idler photons.

关键词： polarization-entangled photon pairs nonlinear interferometer quantum state engineering optical fiber

Sawtooth-enhanced bend sensor for gesture recognition

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Science China(Technological Sciences) 2024年第6期67卷 1727-1736页

作者： BAI YanRu ZHANG ZiHang WANG HaoYu GUO Rui LI XiSheng school of Automation and Electrical engineering University of Science and Technology BeijingBeijing100083China school of Advanced engineering University of Science and Technology BeijingBeijing100083China school of precision instrument and opto-electronics engineering Tianjin UniversityTianjin300072China school of Computer and Communication engineering University of Science and Technology BeijingBeijing100083China

Gesture recognition has diverse application prospects in the field of human-computer ***,gesture recognition devices based on strain sensors have achieved remarkable results,among which liquid metal materials have considerable advantages due to their high tensile strength and *** improve the detection sensitivity of liquid metal strain sensors,a sawtooth-enhanced bending sensor is proposed in this *** with the results from previous studies,the bending sensor shows enhanced resistance *** addition,combined with machine learning algorithms,a gesture recognition glove based on the sawtooth-enhanced bending sensor is also fabricated in this study,and various gestures are accurately *** the fields of human-computer interaction,wearable sensing,and medical health,the sawtooth-enhanced bending sensor shows great potential and can have wide application prospects.

关键词： liquid metal bending sensor gesture recognition machine learning

Sensitivity Improvements for Picosecond Ultrasonic Thickness Measurements in Gold and Tungsten Nanoscale Films

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Nanomanufacturing and Metrology 2024年第2期7卷 1-12页

作者： Jiaqi Dong Chengyuan Yao Yuanhao Zhu Shaojie Li Bowen Liu JinTao Fan Chunguang Hu Youjian Song Minglie Hu Key Laboratory of opto-Electronic Information Science and Technology of Ministry of Education School of Precision Instruments and Opto-Electronics EngineeringTianjin UniversityTianjin 300072China State Key Laboratory of precision Measuring Technology and instruments Tianjin UniversityTianjin 300072China

Picosecond ultrasonics,as a nondestructive and noncontact method,can be employed for nanoscale metallic film thickness *** sensitivity of the system,which determines the measurement precision and practicability of this technique,is often limited by the weak intensity of the ultrasonic *** solve this problem,we investigate the distinct mechanisms involved in picosecond ultrasonic thickness measurement for two types of metals,namely tungsten(W)and gold(Au).For thickness measurement in W films,theory and simulation show that optimizing the pump and probe laser wavelengths,which determine the intensity and shape of the ultrasonic signal,is critical to improving measurement sensitivity,while for Au film measurements,where acoustic-induced beam distortion is dominant,the signal intensity can be optimized by selecting an appropriate aperture size and sample *** above approaches are validated in experiments.A dual-wavelength pump-probe system is constructed based on a passively mode-locked ytterbium-doped fiber *** smoothing method and multipeak Gaussian fitting are employed for the extraction of ultrasonic *** measurement precision is achieved in a series of W and Au films with thicknesses of 43-750 *** work can be applied to various high-precision,noncontact measurements of metal film thickness in the semiconductor industry.

关键词： Picosecond ultrasonics Thickness measurement Optical pump-probe Beam distortion technique

Asymmetric frequency multiplexing topological devices based on a floating edge band

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Photonics Research 2024年第6期12卷 1201-1212页

作者： JIAJUN MA CHUNMEI OUYANG YUTING YANG DONGYANG WANG HONGYI LI LI NIU YI LIU QUAN XU YANFENG LI ZHEN TIAN JIAGUANG HAN WEILI ZHANG center for terahertz waves and College of precision instrument and optoelectronics engineering and Key Laboratory of Optoelectronics Information and TechnologyTianjin UniversityTianjin 300072China school of Materials Science and Physics China University of Mining and TechnologyXuzhou 221116China optoelectronics Research Centre University of SouthamptonSouthampton SO171BJUK Guangxi Key Laboratory of optoelectronic Information Processing School of Optoelectronic EngineeringGuilin University of Electronic TechnologyGuilin 541004China school of Electrical and Computer engineering Oklahoma State UniversityStillwaterOklahoma 74078USA

Topological photonics provides a platform for robust energy transport regardless of sharp corners and ***,the frequency multiplexing topological devices have attracted much attention due to the ability to separate optical signals by wavelength and hence the potential application in optical communication *** frequency multiplexing topological devices are generally based on the slow light ***,the resulting static local spatial mode or finely tuned flat band has zero-group velocity,making it difficult for both experimental excitation and channel ***,we propose and experimentally demonstrate an alternative prototype of asymmetric frequency multiplexing devices including a topological rainbow and frequency router based on floating topological edge mode(instead of localized ones);hence the multiple wavelength channels can be collectively excited with a point source and efficiently routed to separate output *** channel separation in our design is achieved by gradually tuning the band gap truncation on a topological edge band over a wide range of frequencies.A crucial feature lies in that the topological edge band is detached from bulk states and floating within the upper and lower photonic band *** interestingly,due to the sandwiched morphology of the edge band,the top and bottom band gaps will each truncate into transport channels that support topological propagation towards opposite directions,and the asymmetrical transportation is realized for the frequency multiplexing topological devices.

关键词： tuning floating hence

Low-Voltage IGZO Field-Effect Ultraviolet Photodiode

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Chinese Physics Letters 2024年第6期41卷 156-161,I0001-I0003页

作者：宋双梁会力霍文星张广张永晖王绩伟梅增霞 Songshan Lake Materials Laboratory Dongguan 523808China Institute of Physics Chinese Academy of SciencesBeijing 100190China College of Physics Liaoning UniversityShenyang 110036China Department of instruments Science and Technology School of Precision Instrument and Opto-electronics EngineeringTianjin UniversityTianjin 300072China National Key Laboratory of Scattering and Radiation Beijing 100039China school of Physics and optoelectronic engineering Shandong University of TechnologyZibo 255000China

In the era of Internet of Things(Io Ts),an energy-efficient ultraviolet(UV)photodetector(PD)is highly desirable considering the massive usage scenarios such as environmental sterilization,fire alarm and corona discharge *** far,common self-powered UV PDs are mainly based on metal-semiconductor heterostructures or p–n heterojunctions,where the limited intrinsic built-in electric field restricts further enhancement of the *** this work,an extremely low-voltage field-effect UV PD is proposed using a gatedrain shorted amorphous IGZO(a-IGZO)thin film transistor(TFT)architecture.A combined investigation of the experimental measurements and technology computer-aided design(TCAD)simulations suggests that the reverse current(ⅠR)of field-effect diode(FED)is highly related with the threshold voltage(Vth)of the parental TFT,implying an enhancement-mode TFT is preferable to fabricate the field-effect UV PD with low dark *** by a low bias of-0.1 V,decent UV response has been realized including large UV/visible(R_(300)/R_(550))rejection ratio(1.9×10^(3)),low dark current(1.15×10^(-12)A)as well as high photo-to-dark current ratio(PDCR,~10^(3))and responsivity(1.89 A/W).This field-effect photodiode provides a new platform to construct UV PDs with well-balanced photoresponse performance at a low bias,which is attractive for designs of large-scale smart sensor networks with high energy efficiency.

关键词： IGZO attractive ultraviolet

Hollow-structured all-silicon terahertz metasurface supporting quasi-bound states in the continuum for refractive index based Auramine O concentration sensing

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Photonics Research 2024年第7期12卷 1574-1582页

作者： XIN TANG HAODUO JIA LANBIN LI MING LI DAI WU KUI ZHOU PENG LI WEIJUN WANG JITAO LI DINGYU YANG College of optoelectronic engineering Chengdu University of Information TechnologyChengdu 610225China Institute of Applied electronics China Academy of Engineering PhysicsMianyang 621000China school of precision instruments and opto-electronics engineering Tianjin UniversityTianjin 300072China Guizhou Zhenhua Fengguang Semiconductor Co. Ltd.Guiyang 550000China Chengdu Huanyuxin Technology Co. Ltd.Chengdu 610095China

Quasi-bound states in the continuum (QBIC),with exceptionally high-Q factors and the local field enhancement effect,have found potential applications in matter *** the QBIC mechanism into terahertz(THz) metasurfaces can significantly enhance the interaction between incident THz waves and matter,providing a feasible platform for the detection of biochemical ***,most experimental studies on terahertz QBIC metasurfaces utilize metallic *** contrast,research on terahertz all-dielectric QBIC metasurfaces generally remains at the simulation stage due to the high fabrication process requirements,and transitioning to the experimental stage still poses many *** this paper,a hollow-structured all-silicon metasurface supporting THz QBIC is *** resonance of THz QBIC is excited via a simple hollow structure and observed in *** and experimental results demonstrated that the designed THz QBIC metasurface can achieve sensing of Auramine ***,it is the first study,to our knowledge,to employ a metasurface to sense Auramine ***,the sensing performance maintains good stability under different humidity and temperature *** study provides new references and insights for the design and implementation of THz QBIC,and also opens a new pathway for the detection of Auramine O.

关键词： supporting continuum refractive

On-chip terahertz orbital angular momentum demultiplexer

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Photonics Research 2024年第5期12卷 1044-1054页

作者： XIAOHAN JIANG WANYING LIU QUAN XU YUANHAO LANG YIKAI FU FAN HUANG HAITAO DAI YANFENG LI XUEQIAN ZHANG JIANQIANG GU JIAGUANG HAN WEILI ZHANG center for terahertz waves College of Precision Instrument and Optoelectronics Engineeringand Key Laboratory of Optoelectronics Information and Technology(Ministry of Education)Tianjin UniversityTianjin 300072China tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology School of ScienceTianjin UniversityTianjin 300072China Guangxi Key Laboratory of optoelectronic Information Processing School of Optoelectronic EngineeringGuilin University of Electronic TechnologyGuilin 541004China school of Electrical and Computer engineering Oklahoma State UniversityStillwaterOklahoma 74078USA

The terahertz regime is widely recognized as a fundamental domain with significant potential to address the demands of next-generation wireless *** parallel,mode division multiplexing based on orbital angular momentum(OAM)shows promise in enhancing bandwidth utilization,thereby expanding the overall communication channel *** this study,we present both theoretical and experimental demonstrations of an on-chip terahertz OAM *** device effectively couples and steers seven incident terahertz vortex beams into distinct high-quality focusing surface plasmonic beams,and the focusing directions can be arbitrarily *** proposed design strategy integrates space-to-chip mode conversion,OAM recognition,and on-chip routing in a compact space with subwavelength thickness,exhibiting versatility and superior performance.

关键词： demultiplexer momentum angular

High-timing-precision detection of single X-ray photons by superconducting nanowires

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National Science Review 2024年第1期11卷 194-203页

作者： Shuya Guo Jingrou Tan Hengbin Zhang Jinguang Wang Tianhao Ji Labao Zhang Xiaolong Hu Jian Chen Jun Xie Kai Zou Yun Meng Xiaomin Bei Ling-An Wu Qi Chen Hao Wang Xuecou Tu Xiaoqing Jia Qing-Yuan Zhao Lin Kang Peiheng Wu Research Institute of Superconductor electronics Nanjing University Qian Xuesen Laboratory of Space Technology Beijing National Laboratory of Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Hefei National Laboratory school of precision instrument and optoelectronic engineering Tianjin University Key Laboratory of optoelectronic Information Science and Technology Ministry of Education

Precisely acquiring the timing information of individual X-ray photons is important in both fundamental research and practical applications. The timing precision of commonly used X-ray single-photon detectors remains in the range of one hundred picoseconds to microseconds. In this work, we report on high-timing-precision detection of single X-ray photons through the fast transition to the normal state from the superconductive state of superconducting nanowires. We successfully demonstrate a free-running X-ray single-photon detector with a timing resolution of 20.1 ps made of 100-nm-thick niobium nitride film with an active area of 50 μm by 50 μm. By using a repeated differential timing measurement on two adjacent X-ray single-photon detectors, we demonstrate a precision of 0.87 ps in the arrival-time difference of X-ray photon measurements. Therefore, our work significantly enhances the timing precision in X-ray photon counting, opening a new niche for ultrafast X-ray photonics and many associated applications.

关键词： single-photon detection timing precision superconductor ultrafast phenomenon pulsar X-ray navigation

Field stabilization of pulse duration in a hundredfemtosecond level

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Chinese Optics Letters 2024年第8期 98-104页

作者：刘润民吴勇蒲国庆成嘉阳慕桓刘博文义理林胡明列 Ultrafast Laser Laboratory Key Laboratory of Opto-electronic Information Science and Technology of Ministry of EducationSchool of Precision Instruments and Opto-electronics EngineeringTianjin University State Key Laboratory of Advanced Communication Systems and Networks School of Electronic Information and Electrical EngineeringShanghai Jiao Tong University R&D center AIOPTICS Company Limited

Pulse duration is considered as one of the most important characteristics of high-power femtosecond lasers. However,pulses output from the laser system are susceptible to ambient changes and manifest the instability of pulse durations in an open environment. In this paper, incorporating the algorithmic framework of the improved stochastic hill-climbing search and incremental proportional-integral controller, temperature-induced fluctuations of pulse duration can be effectively compensated by an automatic feedback control in an all-fiber chirped-pulse amplification system. In the experiment,sub-hundred femtosecond fluctuation of pulse duration is introduced to verify the performance robustness of the proposed pulse-duration feedback control (PDFC). The stability of pulse duration is obviously higher than the case without the feedback control, and the peak-to-peak fluctuation of pulse duration is reduced to 6.5%. Furthermore, the robust switching between different pulse durations proves the versatility of the PDFC. We expect that the proposed feedback control method could provide a novel insight into high-power femtosecond lasers widely applied in fundamental researches and industrial fields.

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