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Non-invasive optical focusing inside strongly scattering media with linear fluorescence

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arXiv 2020年

作者： Li, Dayan Sahoo, Sujit Kumar Lam, Huy Quoc Wang, Dong Dang, Cuong Nanyang Technological University Singapore 50 Nanyang Avenue Singapore639798 Singapore School of Electrical Sciences Indian Institute of Technology Goa Goa403401 India Temasek Laboratories @ Nanyang Technological University 50 Nanyang Avenue 639798 Singapore Key Laboratory of Advanced Transducers and Intelligent Control System Ministry of Education and Shanxi Province College of Physics and Optoelectronics Taiyuan University of Technology Taiyuan030024 China

Non-invasive optical focusing inside scattering media is still a big challenge because inhomogeneous media scatter both incoming photons for focusing and outgoing photons for observation. Various approaches, utilizing non-linear fluorescence or ultrasound, have been reported to address this difficulty. However, implementation of these methods is complicated and highly expensive, as ultrafast laser systems or photo-acoustic equipment must be employed. Here, we demonstrate a wavefront shaping technique to achieve non-invasive focusing (NiF) inside scattering media using only a linear fluorescent signal. Contrast and mean of incoherent speckles, produced by the linear fluorescence, are utilized as feedback signals to optimize the input wavefront. While increasing speckle contrast makes the focus tighter, and increasing the speckle mean enhances the intensity, fine-tuning the contribution of these two factors in our two-step optimization is essential. An optimal wavefront is found to achieve simultaneously both a micrometer focal spot size (down to 20 μm diameter) and high intensity (more than a 100-fold enhancement) inside the scattering media. Our method promises a new route in life science towards focusing, imaging or manipulating deep into biological tissues with linear fluorescent agents. Copyright © 2020, The Authors. All rights reserved.

关键词： Fluorescence

Charged Lovelock black holes in the presence of dark fluid with a nonlinear equation of state

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arXiv 2019年

作者： Li, Xiang-Qian Chen, Bo Xing, Li-Li College of Physics and Optoelectronic Engineering Taiyuan University of Technology Taiyuan030024 China Key Laboratory of Advanced Transducers and Intelligent Control System Ministry of Education and Shanxi Province Taiyuan University of Technology Taiyuan030024 China

We consider a model that charged static spherically-symmetric black hole is surrounded by dark fluid with nonlinear equation of state pd = -B/ρd. We find that the energy density of the dark fluid can be characterized by two parameters. The derivation of metric solution, as well as the calculation of black hole thermodynamical quantities as functions of horizon radius, are performed. Specially, in D-dimensional Einstein gravity and Gauss-Bonnet gravity cases, we plot the metric functions and corresponding thermodynamical quantities, such as mass, Hawking temperature and heat capacity, by varying the values of spacetime dimensions and dark fluid parameters. The effects of the dark fluid parameters on black hole solutions as well as on thermodynamical stability of black holes are discussed. Copyright © 2019, The Authors. All rights reserved.

关键词： Gravitation

0.75 Gbit/s high-speed classical key distribution with mode-shift keying chaos synchronization of Fabry-Perot lasers

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arXiv 2020年

作者： Gao, Hua Wang, Anbang Wang, Longsheng Jia, Zhiwei Guo, Yuanyuan Gao, Zhensen Yan, Lianshan Qin, Yuwen Wang, Yuncai Key Laboratory of Advanced Transducers and Intelligent Control System Ministry of Education and Shanxi Province Taiyuan China College of Physics and Optoelectronics Taiyuan University of Technology Taiyuan China School of Information Engineering Guangdong University of Technology Guangzhou China Guangdong Provincial Key Laboratory of Photonics Information Technology Guangzhou China Center for Information Photonics and Communications School of Information Science and Technology Southwest Jiaotong University Chengdu China

High-speed physical key distribution is diligently pursued for secure communication. In this paper, we propose and experimentally demonstrate a scheme of high-speed key distribution using mode-shift keying chaos synchronization between two multi-longitudinal-mode Fabry–Perot lasers commonly driven by a super-luminescent diode. Legitimate users dynamically select one of the longitudinal modes according to private control codes to achieve mode-shift keying chaos synchronization. The two remote chaotic light waveforms are quantized to generate two raw random bit streams, and then those bits corresponding to chaos synchronization are sifted as shared keys by comparing the control codes. In this method, the transition time, i.e., the chaos synchronization recovery time is determined by the rising time of the control codes rather than the laser transition response time, so the key distribution rate is improved greatly. Our experiment achieved a 0.75-Gbit/s key distribution rate with a bit error rate of 3.8 × 10-3 over 160-km fiber transmission with dispersion compensation. The entropy rate of the laser chaos is evaluated as 16 Gbit/s, which determines the ultimate final key rate together with the key generation ratio. It is therefore believed that the method pays a way for Gbit/s physical key distribution. © 2020, CC0.

关键词： Synchronization

Temperature Sensing Characteristics of Surface Acoustic Wave Brillouin Scattering in Optical Microfibers

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Temperature Sensing Characteristics of Surface Acoustic Wave...

Progress in Electromagnetic Research Symposium (PIERS)

作者： Yi Liu Yuanqi Gu Pengfei Chen Rongrong Guo Yao Yao Yajun You Wenjun He Xiu-Jian Chou Key Laboratory of Advanced Transducers and Intelligent Control System Ministry of Education and Shanxi Province Taiyuan University of Technology 79 West Yingze Street Taiyuan China Institute of Optoelectronic Engineering College of Physics and Optoelectronics Taiyuan University of Technology 79 West Yingze Street Taiyuan China Strong Digital Technology Co. Ltd. (Thinvent) Nanchang China Key Laboratory of Instrumentation Science and Dynamic Measurement Ministry of Education North University of China 3 Xueyuan Street Taiyuan China College of Mechatronics Engineering North University of China Taiyuan China Science and Technology on Electronic Test and Measurement Laboratory School of Instrument and Electronics North University of China Taiyuan China

ISBN: (纸本)9781665409889

Abstract-Temperature sensing characteristics of surface acoustic wave Brillouin scattering in 1-1.3 $\mu\mathrm{m}$ diameter optical microfibers are simulated by using the elastodynamic equation including the electrostrictive stress. A multi-peak Brillouin gain spectrum with rather high scattering efficiency is observed. The highest temperature sensitivity of the surface acoustic mode is 0.568 MHz/°C. Meanwhile, the temperature sensitivity of the surface acoustic mode is less affected by fiber diameter changes, ranging from 0.05 to 0.25 MHz/°C/$\mu\mathrm{m}$. It can be found that using SAW BS for temperature sensing would put less stress on manufacturing constraints for optical microfibers. Moreover, the results provide guidance for the further improving the performance of temperature sensing in the microelectronics field.

关键词： Temperature sensors Optical fibers Optical fiber sensors Temperature distribution Sensitivity Surface acoustic waves Microelectronics

Real-world Robot Reaching Skill Learning Based on Deep Reinforcement Learning

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Real-world Robot Reaching Skill Learning Based on Deep Reinf...

第32届中国控制与决策会议

作者： Naijun Liu Tao Lu Yinghao Cai Rui Wang Shuo Wang State Key Laboratory of Management and Control for Complex Systems Institute of Automation Chinese Academy of Sciences University of Chinese Academy of Sciences Guangdong Provincial Key Lab of Robotics and Intelligent System Shenzhen Institutes of Advanced TechnologyChinese Academy of Sciences Center for Excellence in Brain Science and Intelligence Technology of the Chinese Academy of Sciences

Traditional programming method can achieve certain manipulation tasks with the assumption that robot environment is known and ***,with robots gradually applied in more domains,robots often encounter working scenes which are complicated,unpredictable,and *** overcome the limitation of traditional programming method,in this paper,we apply deep reinforcement learning(DRL) method to train robot agent to obtain skill *** policy trained with DRL on real-world robot is time-consuming and costly,we propose a novel and simple learning paradigm with the aim of training physical robot ***,our method train a virtual agent in an simulated environment to reach random target position from random initial ***,virtual agent trajectory sequence obtained with the trained policy,is transformed to real-world robot command with coordinate transformation to control robot performing reaching *** show that the proposed method can obtain self-adaptive reaching policy with low training cost,which is of great benefits for developing intelligent and robust robot manipulation skill system.

关键词： Robot reaching skill learning deep reinforcement learning

Atom-assisted second-order sideband generation in an optomechanical system with atom-cavity-resonator coupling

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Physical Review A 2019年第6期99卷 063810-063810页

作者： Bin Chen Lei Shang Xiao-Fang Wang Jian-Bin Chen Hai-Bin Xue Xin Liu Jie Zhang Department of Physics College of Physics and Optoelectronics Taiyuan University of Technology Taiyuan Shanxi 030024 China Key Laboratory of Advanced Transducers and Intelligent Control System Ministry of Education and Shanxi Province Taiyuan Shanxi 030024 China State Key Laboratory of Quantum Optics and Quantum Optics Devices Shanxi University Taiyuan 030006 China

Second-order sideband generation (SSG) is investigated in an optomechanical system with atom-cavity-resonator coupling. We focus mainly on the effect of the atomic ensemble trapped in the cavity on the SSG. The numerical results show that the second-order sideband is induced not only for the blue probe-pump detuning resonant case but also for the red one while coupling the atoms with the cavity. Moreover, it is found that the efficiency of the SSG can be significantly enhanced while increasing the atom-cavity coupling strength. More interestingly, the SSG is also sensitive to the atom-pump detuning. It is demonstrated that when optimizing this detuning and the atom-cavity coupling strength together, a robust second-order sideband can be induced and the efficiency of the SSG even surpasses the one of the first-order sideband generation. In addition, the efficiency of the SSG can also be tuned effectively by the decay rate of the atom.

关键词： Atoms, ions, & molecules in cavities Optomechanics Second order nonlinear optical processes Perturbative methods Rotating wave approximation

Correction to: Dielectric properties and nonlinear I–V electrical behavior of (Li1+, Al3+) co-doped CaCu3Ti4O12 ceramics

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Applied Physics A 2019年第9期125卷 1-2页

作者： Sun, Li Ni, Qing Guo, Jianqin Cao, Ensi Hao, Wentao Zhang, Yongjia Ju, Lin Key Lab of Advanced Transducers and Intelligent Control System Ministry of Education Taiyuan University of Technology Taiyuan People’s Republic of China College of Physics and Optoelectronics Taiyuan University of Technology Taiyuan People’s Republic of China College of Physics and Electrical Engineering Anyang Normal University Anyang People’s Republic of China

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Performance Improvement of Raman Distributed Temperature system by Using Noise Suppression

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Photonic Sensors 2018年第2期8卷 103-113页

作者： Jian LI Yunting LI Mingjiang ZHANG Yi LIU Jianzhong ZHANG Baoqiang YAN Dong WANG Baoquan JIN Key Laboratory of Advanced Transducers and Intelligent Control System of Ministry of Education Taiyuan University of Technology Taiyuan 030024 China College of Physics and Optoelectronics Institute of Optoelectronic Engineering Taiyuan University of Technology Taiyuan 030024 China

In Raman distributed temperature system, the key factor for performance improvement is noise suppression, which seriously affects the sensing distance and temperature accuracy. Therefore, we propose and experimentally demonstrate dynamic noise difference algorithm and wavelet transform modulus maximum （WTMM） to de-noising Raman anti-Stokes signal. Experimental results show that the sensing distance can increase from 3 kin to 11.5 km and the temperature accuracy increases to 1.58 ℃ at the sensing distance of 10.4kin.

关键词： Optical fiber sensors Raman scattering noise suppression wavelet transform modulus maximum

Seebeck and Nernst effects in topological insulator: The case of strained HgTe

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arXiv 2021年

作者： Peña, Francisco J. Negrete, Oscar Ma, Ning Vargas, Patricio Reis, Mario Lima, Leandro R.F. Departamento de Física Universidad Técnica Federico Santa María Casilla Valparaíso110-V2390123 Chile Centro para el Desarrollo de la Nanociencia y la Nanotecnología Santiago8320000 Chile Department of Physics College of Physics and Optoelectronic Engineering MOE Key Laboratory of Advanced Transducers Intelligent Control System Taiyuan University of Technology Taiyuan030024 China Institute of Physics Fluminense Federal University Av. Gal. Milton Tavares de Souza s/n Niteroi-RJ24210-346 Brazil Departamento de Física Instituto de Ciências Exatas Universidade Federal Rural do Rio de Janeiro Seropédica - RJ23897-000 Brazil

We theoretically study the thermoelectric transport properties of strained HgTe in the topological insulator phase. We developed a model for the system using a Dirac Hamiltonian including the effect of strain induced by the interface between HgTe and the CdTe substrate. The conductivity tensor was explored assuming the electrons are scattered by charge impurities, while the thermopower tensor was addressed using the Mott relation. Seebeck and Nernst responses exhibit remarkable enhancements in comparison with other two-dimensional Dirac materials, such as graphene, germanane, prosphorene and stanene. The intensity of these termoeletric responses, their dependencies with the external perpendicular magnetic field and temperature are also addressed. Copyright © 2021, The Authors. All rights reserved.

关键词： Cadmium telluride