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Inverse-designed Jones matrix metasurfaces for high-performance meta-polarizers

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Chinese Optics Letters 2024年第2期22卷 192-199页

作者：王志强李枫竣邓倩媚万舟李向平邓子岚 Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications Institute of Photonics TechnologyJinan UniversityGuangzhou 510632China

Polarizers have always been an important optical component for optical engineering and have played an indispensable part of polarization imaging *** polarizers provide an excellent platform to achieve miniaturization,high resolution,and low cost of polarization imaging ***,we proposed freeform metasurface polarizers derived by adjoint-based inverse design of a full-Jones matrix with gradient-descent *** designed multiple freeform polarizers with different filtered states of polarization(SOPs),including circular polarizers,elliptical polarizers,and linear polarizers that could cover the full Poincaré*** that near-unitary polarization dichroism and the ultrahigh polarization extinction ratio(ER)reaching 50 d B were achieved for optimized circular *** multiple freeform polarizers with filtered polarization state locating at four vertices of an inscribed regular tetrahedron of the Poincarésphere are designed to form a full-Stokes parameters micropolarizer *** work provides a novel approach,we believe,for the design of meta-polarizers that may have potential applications in polarization imaging,polarization detection,and communication.

关键词： metasurface inverse design Jones matrix polarization imaging

Remote sensing of air pollution incorporating integrated-path differential-absorption and coherent-Doppler lidar

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Defence Technology（防务技术） 2024年第1期31卷 594-601页

作者： Ze-hou Yang Yong Chen Chun-li Chen Yong-ke Zhang Ji-hui Dong Tao Peng Xiao-feng Li Ding-fu Zhou School of Physics Beijing Institute of TechnologyBeijing 100081China Southwest institute of Technical Physics Chengdu 610041SichuanChina School of Optics and photonics Beijing Institute of TechnologyBeijing 100081China

An innovative complex lidar system deployed on an airborne rotorcraft platform for remote sensing of atmospheric pollution is proposed and *** system incorporates integrated-path differential absorption lidar(DIAL) and coherent-doppler lidar(CDL) techniques using a dual tunable TEA CO_(2)laser in the 9—11 μm band and a 1.55 μm fiber *** combining the principles of differential absorption detection and pulsed coherent detection,the system enables agile and remote sensing of atmospheric *** static tests validate the system’s real-time detection capabilities,including the measurement of concentration-path-length product(CL),front distance,and path wind speed of air pollution plumes over long distances exceeding 4 *** experiments is conducted with the *** of the pollutant concentration and the wind field is carried out in an approximately 1 km slant range over scanning angle ranges from 45°to 65°,with a radial resolution of 30 m and10 *** test results demonstrate the system’s ability to spatially map atmospheric pollution plumes and predict their motion and dispersion patterns,thereby ensuring the protection of public safety.

关键词： Differential absorption LIDAR Coherent Doppler lidar Remoting sensing Atmospheric pollution

Line-scanning microscopy with laterally symmetric imaging using simultaneous cross-line illumination

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photonics Research 2024年第7期12卷 1513-1521页

作者： DAN SHEN YAFENG LI MENG WANG YUTONG HAN BOLIN LU HUI GONG QINGMING LUO JING YUAN Britton Chance Center for Biomedical photonics and MoE Key Laboratory for Biomedical photonics Wuhan National Laboratory for OptoelectronicsHuazhong University of Science and TechnologyWuhan 430074China HUST-Suzhou institute for Brainsmatics JITRI Institute for BrainsmaticsSuzhou 215123China School of Biomedical Engineering Hainan UniversityHaikou 570228China

Using an on-the-fly scanning scheme, line confocal microscopy can obtain complex structures of large biological tissues with high throughput. Yet, it suffers from lateral imaging asymmetry and thus introduces the potential deformations of the observation results. Here, we propose cross-line illumination microscopy (cLIM) that acquires the imaging data of two perpendicular directions simultaneously through the same objective lens in a line scanning and utilizes two-direction deconvolution fusion to achieve lateral symmetric imaging *** fluorescence beads indicates that cLIM reduces lateral resolution asymmetry from 46.1%to 2.5%and improves lateral resolution by 31.0%, compared with traditional line-scanning imaging. Compared with commercial point-confocal microscopy, the cLIM has a 25.84×increase in imaging speed and 1.93×better background-suppressing ability when imaging an 11,306μm×7783μm×100μm mouse kidney slice. We also show the advantages of the cLIM in observing direction-sensitive texture features by imaging a muscular tissue slice. cLIM offers a novel solution to achieve laterally symmetric line-scanning imaging with simple modifications while maintaining high throughput and accuracy for imaging large-scale samples.

关键词： illumination simultaneous scanning

Efficient second and third harmonic generation in dual-layer lithium niobate microdisk resonator

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Science China(Physics,Mechanics & Astronomy) 2024年第5期67卷 33-38页

作者： Zhenzhong Hao Xiao Wu Qiang Luo Zhang Li Rui Ma Fang Bo Feng Gao Guoquan Zhang Jingjun Xu MOE Key Laboratory of Weak-Light Nonlinear photonics TEDA Institute of Applied Physics and School of PhysicsNankai UniversityTianjin 300457China

Lithium niobate thin film frequency doubler has extensive applications in the preparation of classical and quantum *** this study,we successfully fabricated microdisk resonators with a quality factor of 2.2×10^(5) in reverse-polarization dual-layer x-cut lithium niobate for the first *** on the modal phase matching condition,efficient second harmonic generation with a record normalized conversion efficiency of~56000%W-1 and cascaded third harmonic generation with an efficiency of~6500%W-2 were obtained in the microdisk *** with the periodically poled lithium niobate microcavity,the complex domain structure preparation processes are *** work provides a scheme for achieving highly efficient second-order nonlinear effects in non-periodically poled microcavities.

关键词： harmonic lithium niobate

Random pinhole attenuator for high-power laser beams

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High Power Laser Science and Engineering 2024年第3期12卷 116-121页

作者： Seong Cheol Park Hyeok Yun Jin Woo Yoon Seong Ku Lee Jae Hee Sung Il Woo Choi Chang Hee Nam Kyung Taec Kim Department of Physics and Photon Science Gwangju Institute of Science and TechnologyGwangjuRepublic of Korea Center for Relativistic Laser Science Institute for Basic ScienceGwangjuRepublic of Korea Advanced photonics Research institute Gwangju Institute of Science and TechnologyGwangjuRepublic of Korea

The intensity attenuation of a high-power laser is a frequent task in the measurements of optical *** intensity can be attenuated by inserting an optical element,such as a partial reflector,polarizer or absorption *** devices are,however,not always easily applicable,especially in the case of ultra-high-power lasers,because they can alter the characteristics of a laser beam or become easily *** this study,we demonstrated that the intensity of a laser beam could be effectively attenuated using a random pinhole attenuator(RPA),a device with randomly distributed pinholes,without changing the beam *** this device,a multi-PW laser beam was successfully attenuated and the focused beam profile was measured without any alterations of its *** addition,it was confirmed that the temporal profile of a laser pulse,including the spectral phase,was ***,the RPA possesses significant potential for a wide range of applications.

关键词： high-power laser intensity attenuation laser diagnostics

Investigation of crack segmentation and fast evaluation of crack propagation, based on deep learning

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Frontiers of Structural and Civil Engineering 2024年第4期18卷 516-535页

作者： Than V.TRAN H.NGUYEN-XUAN Xiaoying ZHUANG institute of photonics Leibniz University HannoverHannover 30167Germany CIRTech institute HUTECH UniversityHo Chi Minh City 700000Vietnam College of Civil Engineering Tongji UniversityShanghai 200092China

Identifying crack and predicting crack propagation are critical processes for the risk assessment of engineering *** traditional approaches to crack modeling are faced with issues of high computational costs and excessive computing *** address this issue,we explore the potential of deep learning(DL)to increase the efficiency of crack detection and forecasting crack ***,there is no single algorithm that can fit all data sets well or can apply in all cases since specific tasks *** the paper,we present DL models for identifying cracks,especially on concrete surface images,and for predicting crack ***,SegNet and U-Net networks are used to identify concrete *** gradient descent(SGD)and adaptive moment estimation(Adam)algorithms are applied to minimize loss function during ***,time series algorithms including gated recurrent unit(GRU)and long short-term memory(LSTM)are used to predict crack *** experimental findings indicate that the U-Net is more robust and efficient than the SegNet for identifying crack segmentation and achieves the most outstanding *** evaluation of crack propagation,GRU and LSTM are used as DL models and results show good agreement with the experimental data.

关键词： deep learning crack segmentation crack propagation encoder−decoder recurrent neural network

Very long wave infrared quantum dot photodetector up to 18μm

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Light(Science & Applications) 2024年第4期13卷 772-782页

作者： Xiaomeng Xue Qun Hao Menglu Chen School of Optics and photonics Beijing Institute of TechnologyBeijing 100081China. Westlake institute for Optoelectronics FuyangHangzhou 311421China. Physics Department Changchun University of Science and TechnologyChangchun 130022China

Colloidal quantum dots(CQDs)are of interest for optoelectronic devices because of the possibility of high-throughput solution processing and the wide energy gap tunability from ultraviolet to infrared *** may question about the upper limit on the CQD wavelength *** date,although the CQD absorption already reaches terahertz,the practical photodetection wavelength is limited within mid-wave *** figure out challenges on CQD photoresponse in longer wavelength,would reveal the ultimate property on these ***’s more,it motivates interest in bottom-up infrared photodetection with less than 10%cost compared with epitaxial growth semiconductor *** this work,developing a re-growth method and ionic doping modification,we demonstrate photodetection up to 18μm wavelength on HgTe *** liquid nitrogen temperature,the responsivity reaches 0.3 A/W and 0.13 A/W,with specific detectivity 6.6×108 Jones and 2.3×109 Jones for 18μm and 10μm CQD photoconductors,*** work is a step toward answering the general question on the CQD photodetection wavelength limitation.

关键词： quantum wave ultraviolet

Fabrication of Mie-resonant silicon nanoparticles using laser annealing for surface-enhanced fluorescence spectroscopy

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Microsystems & Nanoengineering 2024年第2期10卷 133-141页

作者： Tatsuya Fukuta Ryo Kato Takuo Tanaka Taka-aki Yano institute of Post-LED photonics Tokushima University2-1 Minami-JosanjimaTokushima770-8506Japan Innovative Photon Manipulation Research Team RIKEN Center for Advanced PhotonicsWakoSaitama351-0198Japan Metamaterials Laboratory RIKEN Cluster for Pioneering ResearchWakoSaitama351-0109Japan

Silicon nanostructures with unique Mie resonances have garnered considerable attention in the field of ***,we present a simple and efficient method for the fabrication of silicon(Si)nanoparticle substrates using continuous-wave(CW)laser *** resulting silicon nanoparticles exhibit Mie resonances in the visible region,and their resonant wavelengths can be precisely ***,laser-annealed silicon nanoparticle substrates show a 60-fold enhancement in *** tunable and fluorescence-enhancing silicon nanoparticle platform has tremendous potential for highly sensitive fluorescence sensing and biomedical imaging applications.

关键词： nanoparticles annealing resonant

Mode-dependent dynamic gain of all-fiber FM-EDFA under various pump manipulation

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Chinese Optics Letters 2024年第2期22卷 128-134页

作者：方翼鸿张心怡黄锡恒曾研许鸥李建平付松年秦玉文 institute of Advanced photonics Technology School of Information EngineeringGuangdong University of TechnologyGuangzhou 510006China Guangdong Provincial Key Laboratory of Information photonics Technology Guangdong University of TechnologyGuangzhou 510006China Key Laboratory of Photonic Technology for Integrated Sensing and Communication Ministry of EducationGuangdong University of TechnologyGuangzhou 510006China

The dynamic gain of a few-mode erbium-doped fiber amplifier(FM-EDFA)is vital for the long-haul mode division multiplexing(MDM)***,we investigate the mode-dependent dynamic gain of an FM-EDFA under various manipulations of the pump ***,we numerically calculate the gain variation with respect to the input signal power,where a modedependent saturation input power occurs under different pump *** under the fixed intensity profile of the pump laser,the saturation input power of each spatial mode is ***,high-order mode pumping leads to a compression of the linear amplification region,even though it is beneficial for the mitigation of the differential modal gain(DMG)arising in all guided ***,we develop an all-fiber 3-mode EDFA,where the fundamental mode of the pump laser can be efficiently converted to the LP_(11)mode using the all-fiber mode-selective coupler(MSC).In comparison with the traditional LP_(01)pumping scheme,the DMG at 1550 nm can be mitigated from 1.61 dB to 0.97 dB under the LP_(11)mode pumping,while both an average gain of 19.93 dB and a DMG of less than 1 dB can be achieved from 1530 nm to 1560 ***,the corresponding signal input saturation powers are reduced by 0.3 dB for the LP_(01)mode and 1.6 dB for the LP_(11)mode,*** theoretical and experimental results indicate that a trade-off occurs between the DMG mitigation and the extension of the linear amplification range when the intensity profile of pump laser is manipulated.

关键词： few-mode erbium-doped fiber amplifier differential modal gain saturation input power