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Tunable magneto-optical polarization device for terahertz waves based on InSb and its plasmonic structure

Photonics Research 2019年第3期7卷 325-331页

作者： QIANYI MU FEI FAN SAI CHEN SHITONG XU CHUANZHONG XIONG XIN ZHANG XIANGHUI WANG SHENGJIANG CHANG Institute of Modern Optics Nankai University Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology State Key Laboratory of Applied Optics Changchun Institute of Optics Fine Mechanics and Physics Chinese Academy of Sciences Nanophotonics and Optoelectronics Research Center Qian Xuesen Laboratory of Space Technology China Academy of Space Technology

The nonreciprocal circular dichroism and Faraday rotation effect for terahertz(THz) waves in longitudinally magnetized InSb were investigated by theoretical and experimental studies in the THz regime, which indicated its ability for a THz circularly polarized isolator, THz circular polarizer, tunable polarization converter, and polarization modulator by manipulation of different magnetic fields. Furthermore, we demonstrated the InSb plasmonics based on its magneto-optical effects combined with artificial microstructure. We found the magnetooptical enhancement mechanisms in this magneto-plasmonic structure, achieving broadband near-perfect orthogonal linear polarization conversion modulated by the weak magnetic field in an experiment with an extinction ratio of 33 dB. Moreover, the magneto-optical modulation with an amplitude modulation depth of 95.8% can be achieved by this device under a weak magnetic field of 150 mT. InSb and its magneto-plasmonic device have broad potential for a THz isolator, magneto-optical modulator, and polarization convertor in THz application systems.

关键词： Tunable magneto-optical polarization device terahertz waves InSb

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Active terahertz spin state and optical chirality in liquid crystal chiral metasurface

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Physical Review Materials 2021年第8期5卷 085201-085201页

作者： Yunyun Ji Fei Fan Ziyang Zhang Zhiyu Tan Xin Zhang Yiwu Yuan Jierong Cheng Shengjiang Chang Institute of Modern Optics Nankai University Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology Tianjin 300350 China Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology Tianjin 300350 China

Dynamic control of photonic spin state and chirality plays a vital role in various applications, such as polarization control, polarization-sensitive imaging, and biosensing. Here, we present a scheme for the flexible and dynamic manipulation of terahertz spin state conversion and optical chirality by combining two achiral structures: an asymmetric metasurface and a layer of anisotropic liquid crystal. The proposed asymmetric metasurface can realize the polarization conversion effect. For the circularly polarized incidence, it exhibits the asymmetric transmission of the spin-flipped states but no spin-locked optical chirality since its geometry is mirror symmetric along with the wave propagation. The introduction of the liquid crystal makes the composite metasurface not only exhibit the spin state conversion but also spin-locked chirality and spin-flipped chirality on account of breaking mirror symmetry, which realizes an electrically active terahertz chiral device. The experimental results show that the asymmetric transmission of the terahertz spin states can be dynamically manipulated, resulting in a large controllable range 83.8% to −30.7% of spin-locked circular dichroism at 0.76 THz and −98.2% to 44.7% of spin-flipped circular dichroism at 0.73 THz. This work paves the way for the development of terahertz meta devices capable of enabling active photonic spin state and chirality manipulation.

关键词： Chirality Metamaterials Polarization of light Liquid crystals Terahertz techniques

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Flexible control of terahertz chirality in twisted nematic liquid crystal cell with submillimeter thickness

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Physical Review Materials 2023年第9期7卷 095602-095602页

作者： Hui-Jun Zhao Fei Fan Song-Lin Jiang Xin-Hao Jiang Yun-Yun Ji Sheng-Jiang Chang Institute of Modern Optics Nankai University Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology Tianjin 300350 China Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology Tianjin 300350 China

Liquid crystal (LC), an anisotropic and tunable material, is widely used in phase shifters, polarization converters, and chiral devices. However, it is difficult for simple LC devices to achieve strong chiral response in the terahertz regime, even for cholesteric LCs. In this paper, we observe a strong optical rotation effect in a twisted nematic (TN) LC cell with submillimeter thickness; moreover, the magnetic field disturbance breaks the mirror symmetry of the whole structure and a discontinuous TN LC molecular alignment is formed, thus realizing the strong circular dichroism effect. The above two effects can also be actively tuned by electrically controlling the arrangement of LC molecules. First, without applying an external magnetic field, the dynamic modulation of the optical rotation angle in the above TN LC device can be as high as about 75∘. Then, when a magnetic field in the x-axis direction is applied, the dynamic manipulation range of circular dichroism in the TN LC device can be up to 35 dB. Meanwhile, the dynamic polarization conversion function (from LP to CP or LP to LP) can also be achieved. The optical rotation and circular dichroism effect of this TN LC with submillimeter thickness offer a clear physical picture for the development of efficient and active terahertz polarization conversion and chiral devices.

关键词： Chirality Optical activity Nematic liquid crystals Terahertz techniques

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Active Terahertz-Beam Deflection in a Double-Sided All-Dielectric Metadevice Modulated by both Polarization Rotation and Optical Pumping

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Physical Review Applied 2023年第5期19卷 054086-054086页

作者： Jiayue Liu Fei Fan Zhiyu Tan Huijun Zhao Jierong Cheng Shengjiang Chang Institute of Modern Optics Nankai University Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology Tianjin 300350 China Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology Tianjin 300350 China

Active manipulation of the terahertz (THz) beam, especially beam deflection, is urgently required for wide THz applications. Although Pancharatnam-Berry (PB) metasurfaces can flexibly control the spatial phase distribution of circularly polarized waves, active power distribution and modulation between two conjugate spin beams are still challenging. Here, we demonstrate an all-dielectric metadevice consisting of an anisotropic metasurface layer and a PB metasurface layer etched on both sides of a silicon wafer. This structure develops a photonic spin-decoupling mechanism for spin-beam manipulation, which actively controls the power distribution between the two deflected spin beams by rotating the incident linearly polarized direction. The power-distribution ratio reaches 14.9:1 in the experiment. Moreover, the deflected beam can also be modulated by active switching via a laser pump, achieving an intensity-modulation depth of over 90%. The experimental modulation depth of the metadevice is 52% higher than that of the bare silicon wafer at the same pump power, which originates from the THz localized field enhancement and the strong dispersion effect of the PB structures. Therefore, this work provides a scheme for actively manipulating THz-beam deflection, realizing controllable wave-division multiplexing, power distribution, polarization control, and modulation.

关键词： Beam control Geometric & topological phases Metasurfaces Optical pumping Polarization of light Dielectrics Terahertz techniques Terahertz time-domain spectroscopy

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Collision Dynamic between Soliton Molecule and Single Soliton

Collision Dynamic between Soliton Molecule and Single Solito...

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Asia Communications and Photonics Conference and Exhibition (ACP)

作者： Jiangyong He Mengjie Zhou Congcong Liu Yange Liu Yang Yue Dengke Xing Kaiyan Zhu Kun Chang Zhi Wang Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology Institute of Modern Optics Nankai University Tianjin China

ISBN: (纸本)9781665410953

For the first time, we used the DFT technology to detect the collision process of single soliton and soliton molecules. Our work reveals the complete dynamic process of elastic collision of single soliton and soliton molecule, especially the soliton molecule disintegrating and the reform of soliton molecule. Numerical simulation shows that gain dynamics is the main physical origin of collision. Our investigations illustrate the particle nature of soliton and supplements the previous research of soliton collision dynamics.

关键词： Atmospheric measurements Discrete Fourier transforms Asia Solitons Numerical simulation Particle measurements Real-time systems

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Orbital Angular Momentum (OAM) Carried by Asymmetric Vortex Beams for Wireless Communications: Theory and Experiment

Orbital Angular Momentum (OAM) Carried by Asymmetric Vortex ...

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Pacific Rim Conference on Lasers and Electro-Optics (CLEO/Pacific Rim)

作者： Baoluo Yan Zehui Lu Jinyao Hu Tianxu Xu Hao Zhang Wei Lin Huanbao Wu Haifeng Liu Bo Liu Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology Institute of Modern Optics Nankai University Tianjin China

Unlike traditional symmetrical vortex beams, we demonstrate one kind of asymmetric spatial modes, namely Lommel-Gaussian mode carrying OAM for optical communications, which possesses higher channel capacity through or... 详细信息

ISBN: (数字)9781728143330

ISBN: (纸本)9781728152394

关键词： Wireless communication Multiplexing Optical vortices Lasers and electrooptics Orbits Optical fiber communication Laser beams

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Analysis of real-time spectral interference using a deep neural network to reconstruct multi-soliton dynamics in mode-locked lasers

Analysis of real-time spectral interference using a deep neu...

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Asia Communications and Photonics Conference and Exhibition (ACP)

作者： Caiyun Li Jiangyong He Ruijing He Yange Liu Yang Yue Luhe Zhang Longfei Zhu Mengjie Zhou Kaiyan Zhu Zhi Wang Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology Institute of Modern Optics Nankai University Tianjin China

A residual convolutional neural network (RCNN) is introduced to retrieve the separation and relative phase of solitons in soliton molecules in passively mode-locked lasers (PMLs). It proved to be an effective method t... 详细信息

ISBN: (数字)9781943580828

ISBN: (纸本)9781728176567

关键词： Laser mode locking Solitons Optical distortion Interference Real-time systems Phase distortion Photonics

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Beidou B1I signal acquisition scheme based on variable length data accumulation

Beidou B1I signal acquisition scheme based on variable lengt...

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第九届中国卫星导航学术年会

作者： Menghuan Yang Guoping Wang Yingxin Zhao Hong Wu College of Electronic Information and Optical Engineering Nankai University Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology

The Neumann-Hoffman code is modulated in Beidou D1 navigation message,which increases the possibility of bit sign *** puts a constraint on the coherent integration duration for possible bit sign *** acquisition scheme of Beidou B1 I signal has been proposed in this ***,the carrier and sign bit code are deprived by delay and ***,the Doppler shift of the ranging code is *** to the Doppler shift of ranging code,the variable length of data block is accumulated to 1 ms ***,the ranging code phase is detected by FFT-based synchronized *** carrier frequency offset,whose boundary is determined by the Doppler shift of ranging code,is accurately estimated by means of chirp-z *** experiment shows that the method can achieve long-term coherent integration and improve the acquisition probability.

关键词： BDS acquisition bit sign transition Doppler shift chirp-z transform

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Mode Transmission Analysis of Tapered Fiber Based on Coupled Local Mode Theory

Mode Transmission Analysis of Tapered Fiber Based on Coupled...

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Asia Communications and Photonics Conference and Exhibition (ACP)

作者： Siyu Chen Huiyi Guo Zhi Wang Yange Liu Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology Institute of Modern Optics Nankai University Tianjin China

A simulation method of analyzing mode transmission characteristics in tapered fiber based on coupled local mode theory is presented. The method gives a clear analysis of mode component in tapered fiber.

ISBN: (纸本)9781943580705

关键词： Fiber devices Finite element method Optical fibers Single mode fibers Tapered fibers Wavelength division multiplexers

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DTMB and FM Signals Indoor Fingerprint Positioning System based on Compressive sensing

DTMB and FM Signals Indoor Fingerprint Positioning System ba...

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第十一届中国卫星导航年会

作者： Menghuan Yang Hong Wu Hongzhao Peng Zhuo Chen College of Electronic Information and Optical Engineering Nankai University Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology

Location-based services have become an indispensable part of people’s daily lives. GNSS can provide favorable outdoor location services, but it cannot meet the needs of indoor positioning. This paper

关键词： Indoor positioning Fingerprint match Compressive sensing FM signal DTMB signal

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