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Diverse terahertz wavefront manipulations empowered by the spatially interleaved metasurfaces

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Science China(Information Sciences) 2023年第3期66卷 230-238页

作者： Jitao LI Zhen YUE Jie LI chenglong zheng Silei WANG Mengyao LI Yating ZHANG Yan ZHANG Jianquan YAO School of Precision Instruments and Opto-Electronics Engineering Tianjin University College of Optoelectronic Engineering Chengdu University of Information Technology Department of Physics Capital Normal University

Optical metasurfaces have advanced approaches for manipulating light information in the spatial domain, in which the spatially interleaved metasurfaces demonstrate the ability to manipulate a more complex wavefront of light than metasurfaces without the spatial interleaving. The potential of the spatially interleaved metasurfaces has not been fully exploited. In this paper, we design the spatially interleaved terahertz(THz) metasurfaces based on the ingenious spatial interleaving principles to develop the diverse THz wavefront manipulations. Four functions are performed, including the orbital angular momentum(OAM)superposition of single-frequency vortex beams, the separate vortex focusing of single-frequency dual beams,the different OAM manipulations of bifrequency beams in different planes, and achromatic focusing. The demonstrated functions prove that the spatially interleaved metasurface can manipulate THz wavefront at both single frequency and bifrequency, which traditional metasurfaces cannot. This work paves the way for diverse THz wavefront manipulations.

关键词： terahertz wavefront manipulations metasurfaces spatial interleaving onformation optics

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

Terahertz metasurface polarization detection employing vortex pattern recognition

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Photonics Research 2023年第12期11卷 2256-2263页

作者： chenglong zheng JINGYU LIU HUI LI MENGGUANG WANG HUAPING ZANG YAN ZHANG JIANQUAN YAO Key Laboratory of Material Physics Ministry of EducationSchool of Physics and MicroelectronicsZhengzhou UniversityZhengzhou 450052China Beijing Key Laboratory for Metamaterials and Devices Key Laboratory of Terahertz OptoelectronicsMinistry of Educationand Beijing AdvancedInnovation Center for Imaging TechnologyDepartment of PhysicsCapital Normal UniversityBeijing 100048China Key Laboratory of Opto-Electronics Information Technology(Tianjin University) Ministry of EducationSchool of Precision Instruments andOpto-Electronics EngineeringTianjin UniversityTianjin 300072China State Key Laboratory of Modern Optical Instrumentation College of Optical Science and EngineeringZhejiang UniversityHangzhou 310027China

The manipulation and detection of polarization states play a crucial role in the application of 6G terahertz communication.Nonetheless,the development of compact and versatile polarization detection devices capable of detecting arbitrary polarizations continues to be a challenging endeavor.Here,we demonstrate a terahertz polarization detection scheme by performing mode purity analysis and multidimensional analysis of the transmitted vortex field.The power of the proposed polarization recognition is verified by using three polarization trajectories,including linear polarizations,circular polarizations,and elliptical polarizations.Using the reconstructed complete polarization parameters,the detected polarization states are characterized using polarization ellipses,Poincarésphere,and full-Stokes parameters.The experimental results validate the power of this scheme in polarization detection.This scheme holds promise for applications in polarization imaging and terahertz communication.

关键词： polarization scheme pattern

Application of S-transform threshold filtering in Anhui experiment airgun sounding data de-noising

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Geodesy and Geodynamics 2018年第4期9卷 320-327页

作者： chenglong zheng Xiaofeng Tian Zhuoxin Yang Shuaijun Wang Zhenyu Fan Geophysical Exploration Center China Earthquake Administration

As a relatively new method of processing non-stationary signal with high time-frequency resolution, S transform can be used to analyze the time-frequency characteristics of seismic signals. It has the following characteristics: its time-frequency resolution corresponding to the signal frequency, reversible inverse transform, basic wavelet that does not have to meet the permit conditions. We combined the threshold method, proposed the S-transform threshold filtering on the basis of S transform timefrequency filtering, and processed airgun seismic records from temporary stations in "Yangtze Program"(the Anhui experiment). Compared with the results of the bandpass filtering, the S transform threshold filtering can improve the signal to noise ratio(SNR) of seismic waves and provide effective help for first arrival pickup and accurate travel time. The first arrival wave seismic phase can be traced farther continuously, and the Pm seismic phase in the subsequent zone is also highlighted.

关键词： S transform Time-frequency filtering Airgun data Threshold filtering De-noising

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

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引入控制变量的车身噪声传递函数优化研究

汽车技术 2024年第5期 58-62页

作者：郑成龙常林王楷焱宫英伟张新敏北京交通运输职业学院北京100010 中公高远(北京)汽车检测技术有限公司北京100088 沈阳理工大学沈阳110159

为解决车辆整备车身噪声传递函数优化中消除某噪声传递函数声压级峰值时易引发新的噪声声压级峰值的问题,提出引入控制变量的车身噪声传递函数优化方法。以某车型驾驶室为研究对象,构建优化模型,以驾驶室结构板件厚度为变量,利用所提出... 详细信息

为解决车辆整备车身噪声传递函数优化中消除某噪声传递函数声压级峰值时易引发新的噪声声压级峰值的问题,提出引入控制变量的车身噪声传递函数优化方法。以某车型驾驶室为研究对象,构建优化模型,以驾驶室结构板件厚度为变量,利用所提出的算法对涉及的参数进行迭代优化。结果表明,该方法有效降低了目标频带内的噪声传递函数声压级峰值。

关键词：噪声传递函数控制变量贡献量

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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