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Dynamic phase assembled terahertz metalens for reversible conversion between linear polarization and arbitrary circular polarization

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Opto-Electronic Advances 2022年第1期5卷 24-34页

作者： Jitao Li Guocui Wang zhen yue Jingyu Liu Jie Li Chenglong zheng Yating Zhang Yan Zhang Jianquan Yao Key Laboratory of Opto-Electronics Information Technology(Tianjin University) Ministry of EducationSchool of Precision Instruments and Opto-Electronics EngineeringTianjin UniversityTianjin 300072China Beijing Engineering Research Center for Mixed Reality and Advanced Display School of Optics and PhotonicsBeijing Institute of TechnologyBeijing 100081China Beijing Key Laboratory for Metamaterials and Devices Key Laboratory of Terahertz OptoelectronicsMinistry of Educationand Beijing Advanced Innovation Center for Imaging TechnologyDepartment of PhysicsCapital Normal UniversityBeijing 100048China

If a metalens integrates the circular polarization(CP)conversion function,the focusing lens together with circular-polariz-ing lens(CPL)in traditional cameras may be replaced by a metalens.However,in terahertz(THz)band,the reported metalenses still do not obtain the perfect and strict single-handed CP,because they were constructed via Pancharatnam-Berry phase so that CP conversion contained both left-handed CP(LCP)and right-handed CP(RCP)components.In this paper,a silicon based THz metalens is constructed using dynamic phase to obtain single-handed CP conversion.Also,we can rotate the whole metalens at a certain angle to control the conversion of multi-polarization states,which can simply manipulate the focusing for incident linear polarization(LP)THz wave in three polarization conversion states,in-cluding LP without conversion,LCP and RCP.Moreover,the polarization conversion behavior is reversible,that is,the THz metalens can convert not only the LP into arbitrary single-handed CP,but also the LCP and RCP into two perpen-dicular LP,respectively.The metalens is expected to be used in advanced THz camera,as a great candidate for tradi-tional CPL and focusing lens group,and also shows potential application in polarization imaging with discriminating LCP and RCP.

关键词： terahertz metalens metamaterials metasurfaces dynamic phase single-handed circular polarization reversible conversion

Broadband and tunable terahertz absorption via photogenerated carriers in undoped silicon

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Science China(Physics,Mechanics & Astronomy) 2022年第1期65卷 14-21页

作者： Jie Li Jitao Li Chenglong zheng Longhai Liu zhen yue Hang Xu Xuanruo Hao Fuyu Li Tingting Tang Yating Zhang Jianquan Yao Key Laboratory of Opto-Electronics Information Technology(Tianjin University) Ministry of EducationSchool of Precision Instruments and Opto-Electronics EngineeringTianjin UniversityTianjin 300072China Advantest(China)Co. Ltd.Shanghai 201203China Information Materials and Device Applications Key Laboratory of Sichuan Provincial Universities Chengdu University of Information TechnologyChengdu 610225China

Terahertz absorbers based on doped silicon have achieved broadband and high-efficiency absorption due to their high concentration of carriers.However,their tunable performance is obviously insufficient.Here,we propose a new scheme for active terahertz absorption based on undoped silicon with a metamaterial antireflection layer,which realizes both strong absorption and ultrahigh modulation depth.Benefiting from the weak absorption and high transmission of undoped silicon for 1064-nm continuous wave,uniformly distributed carriers across the entire thickness of the absorber are excited,and efficient free carrier absorption of the terahertz wave is obtained.We use only a 500-μm thick absorber and achieve absorption greater than 90%in the range of 0.58 to 1.92 THz,with a peak value of 99%.More important,the absorber can be switched between two working states of nonabsorption and high-efficiency absorption by changing the pump power,which means the modulation depth reaches 100%.This simple and high-performance implementation scheme provides a new idea for the design of terahertz tunable absorbers.

关键词： terahertz carriers silicon metamaterials

Binary encoding-inspired generation of vector vortex beams

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Science China(Physics,Mechanics & Astronomy) 2023年第5期66卷 139-154页

作者： Hui Li Chenglong zheng Jingyu Liu Hang Xu Chunyu Song Fan Yang Jitao Li zhen yue Wei Shi Yating Zhang Yan Zhang Jianquan Yao Key Laboratory of Opto-Electronics Information Technology(Tianjin University) Ministry of EducationSchool of Precision Instruments and Opto-Electronics EngineeringTianjin UniversityTianjin 300072China Beijing Key Laboratory for Metamaterials and Devices Key Laboratory of Terahertz OptoelectronicsMinistry of EducationBeijing Advanced Innovation Center for Imaging TechnologyDepartment of PhysicsCapital Normal UniversityBeijing 100048China

Vortex and vector terahertz(THz)beams with inhomogeneous polarization states have become a considerable hot topic in the last decade due to their important roles in multiplexed wireless data transmission.However,the technical instruments to form and evaluate such beams are rather limited,as they are mainly collected in the visible range.The emergence of coded metasurfaces has reinvigorated the design of functional devices with multiple degrees of freedom.Here,we demonstrate a versatile design inspired by a binary encoding approach for generating off-axis vectorial THz beams on all-silicon metasurfaces.Experimentally,simultaneous manipulation of the encoding method within the orthogonal circularly polarized(CP)channel provides strong support for developing versatility in vector THz beams,including the generation of arbitrary polarization profiles and the directional emission of multiplexed vector vortex beams(VVBs)with specified polarization states.The introduction of the latitudinal polarization control factor guarantees that continuously rotating or independently designed vector polarization profiles can be obtained on a pre-defined focal plane.Subsequently,a universal parametric theoretical model is developed to analyze the evolutionary trend of off-axis VVB in detail.Notably,the proposed monolayer vector metasurface bypasses the requirement of multiple cascaded optical elements,further inducing the advancement of ultra-thin vector THz sources,and also facilitating the generation of vector fields with tailored polarization distributions in 3D space.

关键词： metasurfaces vector beams spin-orbit interactions polarization optics

基于YOLOv8s的改进结核病病原体检测算法

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中国医学物理学杂志 2024年第7期41卷 910-917页

作者：乐振孙振鞠瑞文李庆党青岛科技大学信息科学技术学院山东青岛266061 青岛科技大学数据科学学院山东青岛266061 青岛科技大学中德科技学院山东青岛266061

针对结核病病原体在痰涂片图像背景复杂且目标小,人工筛查成本较高的问题,提出了一种基于YOLOv8s的结核病病原体检测方法。首先,采用基于空间和通道重构卷积改进的结构来限制特征冗余。其次,引入了坐标注意力来扩大模型的感受野。再者,... 详细信息

针对结核病病原体在痰涂片图像背景复杂且目标小,人工筛查成本较高的问题,提出了一种基于YOLOv8s的结核病病原体检测方法。首先,采用基于空间和通道重构卷积改进的结构来限制特征冗余。其次,引入了坐标注意力来扩大模型的感受野。再者,使用空间金字塔池化跨阶段局部网络来提取不同尺度上的特征信息。最后,嵌入基于归一化的注意力机制抑制不太显著的特征。实验结果表明,在公开数据集上,改进网络模型与原YOLOv8s模型相比,精确率和召回率分别提升2.7%和1.5%,置信度为0.5时的平均精度均值提高了2.3%,该模型能够有效辅助影像科医师进行诊断。

关键词：结核病深度学习 YOLOv8 注意力机制

股骨髋臼撞击综合征患者髋关节镜术后并发髋关节炎的危险因素分析

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中国骨伤 2024年第2期37卷 179-183页

作者：柯磊寇文冠马晨张月震刘东帅沧州市人民医院疼痛脊柱微创科河北沧州061000 沧州市人民医院骨三关节运医科河北沧州061000 沧州市人民医院脊柱科河北沧州061000

目的:探讨股骨髋臼撞击(femoro-acetabular impingement,FAI)综合征患者髋关节镜术后并发髋关节炎(hip osteoarthritis,HOA)的危险因素,减少和预防HOA的发生。方法:自2018年9月至2020年9月采用髋关节镜手术治疗106例FAI患者,男40例,女66例;年龄20~55(33.05±10.19)岁;运动伤51例,交通事故伤36例,钝物砸伤19例;病程5~19(12.02±3.69)d。术后随访18个月,根据是否发生HOA将患者分为HOA组23例和无HOA组83例。采用多元Logistic回归分析影响FAI患者髋关节镜术后并发HOA的危险因素。结果:经单因素分析,HOA组年龄50~70岁、女性、身体质量指数>30 kg·m^(-2)、体力劳动、凸轮型、术后并发感染、术后末次随访髋关节关节活动度(range of motion,ROM)及Tonnis分级1级及以上比例均高于无HOA组(P30 kg·m^(-2)、术后末次随访髋关节内旋ROM及Tonnis分级≥1级是FAI患者髋关节镜术后发生HOA的危险因素(P<0.05)。结论:FAI分型、身体质量指数、髋部ROM、Tonnis分级均与FAI患者髋关节镜术后并发HOA有关,对高危FAI患者应加强随访和干预,以减少HOA的发生。

关键词：股骨髋臼撞击综合征髋关节镜髋关节炎凸轮型肥胖 Tonnis分级

Terahertz wavefront shaping with multi-channel polarization conversion based on all-dielectric metasurface

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Photonics Research 2021年第10期9卷 1939-1947页

作者： JIE LI CHENGLONG zhenG JITAO LI GUOCUI WANG JINGYU LIU zhen yue XUANRUO HAO yue YANG FUYU LI TINGTING TANG YATING ZHANG YAN ZHANG JIANQUAN YAO Key Laboratory of Opto-Electronics Information Technology(Tianjin University) Ministry of EducationSchool of Precision Instruments and Opto-Electronics EngineeringTianjin UniversityTianjin 300072China Beijing Key Laboratory for Metamaterials and Devices Key Laboratory of Terahertz OptoelectronicsMinistry of Educationand Beijing Advanced Innovation Center for Imaging TechnologyDepartment of PhysicsCapital Normal UniversityBeijing 100048China Beijing Engineering Research Center for Mixed Reality and Advanced Display School of Optics and PhotonicsBeijing Institute of TechnologyBeijing 100081China Information Materials and Device Applications Key Laboratory of Sichuan Provincial Universities Chengdu University of Information TechnologyChengdu 610225China

Polarization manipulation of electromagnetic wave or polarization multiplexed beam shaping based on metasurfaces has been reported in various frequency bands.However,it is difficult to shape the beam with multi-channel polarization conversion in a single metasurface.Here,we propose a new method for terahertz wavefront shaping with multi-channel polarization conversion via all-silicon metasurface,which is based on the linear shape birefringence effect in spatially interleaved anisotropic meta-atoms.By superimposing the eigen-and non-eigen-polarization responses of the two kinds of meta-atoms,we demonstrate the possibility for high-efficiency evolution of several typical polarization states with two independent channels for linearly polarized waves.The measured polarization conversion efficiency is higher than 70%in the range of 0.9–1.3 THz,with a peak value of 89.2%at 1.1 THz.In addition,when more other polarization states are incident,combined with the integration of sub-arrays,we can get more channels for both polarization conversion and beam shaping.Simulated and experimental results verify the feasibility of this method.The proposed method provides a new idea for the design of terahertz multi-functional metadevices.

关键词： surface. method. dielectric

All-silicon chiral metasurfaces and wavefront shaping assisted by interference

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Science China(Physics,Mechanics & Astronomy) 2021年第11期64卷 69-77页

作者： Chenglong zheng Jie Li Jitao Li zhen yue Silei Wang Mengyao Li Hongliang Zhao Xuanruo Hao Huaping Zang Yating Zhang Jianquan Yao Key Laboratory of Opto-Electronics Information Technology(Tianjin University) Ministry of EducationSchool of Precision Instruments and Opto-Electronics EngineeringTianjin UniversityTianjin 300072China School of Physics and Microelectronics Zhengzhou UniversityZhengzhou 450001China

Chiral metasurfaces have different electromagnetic responses with circularly polarized lights,showing as circular dichroism and optical activity.Here,a novel kind of all-silicon chiral metasurface is proposed by introducing destructive interference between achiral meta-atoms.The maximum value of circular dichroism spectra can reach 0.49.By adding an antireflective layer at the side of the silicon substrate,the maximum circular dichroism reaches 0.54.What is more,the bandwidth of circular dichroism greater than 0.4 reaches 0.15 THz.Two samples are fabricated to verify the feasibility of this scheme,and the experimental results are in good agreement with the simulations.In addition,the proposed scheme can also be used to generate various interesting functions,such as beam control and vortex generator.This flexible and efficient implementation solution of chiral metasurface can bring new ideas to the development of chiral devices in the future.

关键词： metasurface chiral terahertz decoupling

肌源性细胞分化的单细胞转录谱变化及细胞间通讯分析

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生物技术通报 2024年第6期40卷 330-342页

作者：秦健李振月何浪李俊玲张昊杜荣山西农业大学动物医学学院太谷030801 山西农业大学实验教学中心太谷030801

【目的】基于单细胞转录组测序(single-cell RNA sequencing,scRNA-seq)揭示牛肌源性细胞分化中的基因表达谱变化,并探究介导细胞间通讯的配体-受体互作机制,为构建成肌分化的动态调控网络奠定基础。【方法】利用Seurat、ClusterProfile... 详细信息

【目的】基于单细胞转录组测序(single-cell RNA sequencing,scRNA-seq)揭示牛肌源性细胞分化中的基因表达谱变化,并探究介导细胞间通讯的配体-受体互作机制,为构建成肌分化的动态调控网络奠定基础。【方法】利用Seurat、ClusterProfiler、STRING、Cytoscape、CellChatDB和Monocle2等数据库或软件,对NCBI-GEO公共数据库中牛肌源性细胞单细胞转录组测序的原始数据进行了深入分析,包括细胞分群鉴定及差异基因表达谱、相关性、GO富集、PPI、细胞间通讯和拟时序分析等。【结果】根据基因表达相关性及标志性基因共鉴定出4个具有独特转录特征的细胞群Myoblasts、Myocytes、Fibroblasts和FAPs,通过Myoblasts亚群的基因表达谱比较及拟时序分化轨迹分析发现,各亚群之间异质性很强,其中Myoblasts_1为分化轨迹起点,Myoblasts_0和3处于分化早期阶段,而Myoblasts_2是肌肉特征表现最为明显的亚群,可能是临近形成Myocytes的后期阶段的Myoblasts;Myoblasts_2和Myocytes差异基因富集的肌肉相关GO term存在差异,各基因间存在复杂的蛋白互作关系;Myoblasts_0-5、Myocytes、Fibroblasts和FAPs同型或异型细胞间的通讯机制,涉及到PTN-NCL、IGF2-IGF2R和ANGPTL2-(ITGA5+ITGB1)等多种不同的配体-受体作用。【结论】肌源性细胞在分化过程中存在不断变化的基因表达谱和细胞间通讯,反映了复杂的动态异质性及分子调控机制。

关键词：牛肌源性细胞单细胞转录组测序细胞亚群异质性基因表达谱细胞间通讯

Terahertz metasurface zone plates with arbitrary polarizations to a fixed polarization conversion

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Opto-Electronic Science 2022年第3期1卷 9-16页

作者： zhen yue Jitao Li Jie Li Chenglong zheng Jingyu Liu Guocui Wang Hang Xu Mingyang Chen Yating Zhang Yan Zhang Jianquan Yao Key Laboratory of Opto-Electronics Information Technology(Tianjin University) Ministry of EducationSchool of Precision Instruments and Opto-Electronics EngineeringTianjin UniversityTianjin 300072China Beijing Key Laboratory for Metamaterials and Devices Department of PhysicsCapital Normal UniversityBeijing 100048China Beijing Engineering Research Center for Mixed Reality and Advanced Display School of Optics and PhotonicsBeijing Institute of TechnologyBeijing 100081China Department of Optoelectronic Information Science and Engineering Jiangsu UniversityZhenjiang 212013China

Metasurfaces that can realize the polarization manipulation of electromagnetic waves on the sub-wavelength scale have become an emerging research field.Here,a novel strategy of combining the metasurface and Fresnel zone plate to form a metasurface zone plate is proposed to realize the conversion from nearly arbitrary polarizations to a fixed polarization.Specifically,when one polarized wave is incident on adjacent ring zones constructed by different types of meta-atoms,the transmitted waves generated by odd-numbered and even-numbered ring zones converge at the same focus and superimpose to generate a fixed polarized wave.As function demonstrations,we have designed two types of metasurface zone plates:one is a focused linear polarizer,and the other can convert nearly arbitrary polarized waves into focused circularly polarized waves.The simulated and measured results are consistent with theoretical expectations,suggesting that the proposed concept is flexible and feasible.Our work provides an alternative platform for polarization manipulation and may vigorously promote the development of polarization photonic devices.

关键词： metasurface zone plates polarization conversion terahertz