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Widely Tunable Middle Infrared optical Parametric Oscillator Pumped by the Q-Switched Ho：GdVO_4 Laser

Chinese Physics Letters 2018年第5期35卷 48-51页

作者： Xiao-Ming Duan Cheng Chen Yu Ding Bao-Quan Yao Yue-Zhu Wang National Key Laboratory of Tunable Laser Technology Harbin Institute of Technology Harbin 150001 Science and Technology on Electro-Optical Information Security Control Laboratory Tianjin 300308

We demonstrate a middle infrared ZnGeP_2 optical parametric oscillator pumped by the Q-switched Ho：GdVO_4 laser. When the incident Ho pump power is 4.12 W, the maximum average output power of the ZGP-OPO laser is 2.05 W, corresponding to a slope efficiency of 74.6%. The ZGP-OPO laser produces 4.2 ns mid-infrared pulses at a pulse repetition rate of 5 kHz. In addition, we obtain 0.8 um of tunable range for the signal wave and 2.1 um of tunable range for the idler wave.

关键词： Ho OPO Widely Tunable Middle Infrared optical Parametric Oscillator Pumped by the Q-Switched Ho:GdVO4 Laser

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Topologically Enhanced Circular Dichroism from Metasurfaces

引用

Physical Review Applied 2021年第3期16卷 L031001-L031001页

作者： Jiaxin Chen Lishuan Wang Wei Wu Wei Cai Huasong Liu Mengxin Ren Jingjun Xu Key Laboratory of Weak-Light Nonlinear Photonics Ministry of Education School of Physics and TEDA Applied Physics Institute Nankai University Tianjin 300071 People’s Republic of China Science and Technology on Electro-Optical Information Security Control Laboratory Tianjin 300308 People’s Republic of China Tianjin Key Laboratory of Optical Thin Film Tianjin Jinhang Technical Physics Institute Tianjin 300080 People’s Republic of China Collaborative Innovation Center of Extreme Optics Shanxi University Taiyuan Shanxi 030006 People’s Republic of China

Circular dichroism (CD) is one of the most distinctive properties of chiral materials. In recent decades, chiral metasurfaces have been regarded as a promising framework to realize chiral optical devices with ultrathin thickness and compact footprints. Various efforts have been devoted to increase the CD response from such metasurfaces. Here we present a method to enhance the CD effect from metasurfaces utilizing a topological concept. Two multilayered photonic crystals with different topological invariants are adopted and put in contact leading to the appearance of a topological edge state and a distinct electromagnetic field concentration at the interface. By embedding L-shaped chiral metasurfaces into the interface, the CD response is observed to be obviously boosted. We find that due to the robustness feature of the topological edge state, the spectral position of the CD peak is fixed at the edge-state wavelength and is immune to structural variation of the metasurface array. Considering that the multilayered films are easy to fabricate, such a topological concept could act as a simple and feasible strategy for enhancing chiral optical response from nanoscales, and could find wide applications in realizing ultracompact polarization-selective optical components.

关键词： Edge states Metamaterials optical & microwave phenomena Photonics Topological effects in photonic systems Devices

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Delta interferometer: A polarization sensitive interferometer

arXiv

引用

arXiv 2022年

作者： Wei, Chaoqi Liu, Jianbin Sun, Yunong Zhuang, Rui Zhou, Yu Zheng, Huaibin Liu, Yanyan Yan, Xiusheng Li, Fuli Xu, Zhuo Electronic Materials Research Laboratory Key Laboratory of the Ministry of Education & International Center for Dielectric Research Xi’an Jiaotong University Xi’an710049 China The Key Laboratory of Weak Light Nonlinear Photonics Nankai University Ministry of Education Tianjin300457 China MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter Department of Applied Physics Xi’an Jiaotong University Shaanxi Xi’an710049 China Science and Technology on Electro-Optical Information Security Control Laboratory Tianjin300308 China

A new type of polarization sensitive interferometer is proposed, which is named as Delta interferometer due to the geometry of the simplest interferometer looks like Greek letter, Delta. To the best of our knowledge, it is the first time that this type of interferometer is proposed. The main difference between Delta interferometer and other existed interferometer, such as Michelson interferometer, Mach-Zehnder interferometer, Young’s double-slit interferometer, is that the two interfering paths are asymmetrical in Delta interferometer, which makes it polarization sensitive. The visibility of the first-order interference pattern observed in Delta interferometer is dependent on the polarization of the incidental light. optical coherence theory is employed to interpret the phenomenon and a single-mode continuous-wave laser is employed to verify the theoretical predictions. The theoretical and experimental results are consistent. Delta interferometer provides a perfect tool to study the reflection of electric field in different polarizations and may find applications in polarization sensitive scenarios. Copyright © 2022, The Authors. All rights reserved.

关键词： Electric fields

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Theoretical analysis of a polarized two-photon michelson interferometer with broadband chaotic light

arXiv

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arXiv 2021年

作者： Zhou, Yu Luo, Sheng Liu, Jianbin Zheng, Huaibin Chen, Hui He, Yuchen Liu, Yanyan Li, Fuli Xu, Zhuo MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter Department of Applied Physics Xi'An Jiaotong University Shaanxi Xi'an710049 China Electronic Materials Research Laboratory Key Laboratory of the Ministry of Education International Center for Dielectric Research School of Electronic Science and Engineering Xi'An Jiaotong University Shaanxi Xi'an710049 China Science and Technology on Electro-Optical Information Security Control Laboratory Tianjin300308 China

In this paper, we study two-photon interference of broadband chaotic light in a Michelson interferometer with two-photon-absorption detector. The theoretical analysis is based on two-photon interference and Feynman path integral theory. The two-photon coherence matrix is introduced to calculate the second-order interference pattern with polarizations being taken into account. Our study shows that the polarization is another dimension, as well as time and space, to tune the interference pattern in the two-photon interference process. It can act as a switch to manipulate the interference process and open the gate to many new experimental schemes. Copyright © 2021, The Authors. All rights reserved.

关键词： Michelson interferometers

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Nth-order nonlinear intensity fluctuation amplifier

arXiv

引用

arXiv 2021年

作者： Zhang, Shuanghao Zheng, Huaibin Wang, Gao Chen, Hui Liu, Jianbin Zhou, Yu He, Yuchen Luo, Sheng Liu, Yanyan Xu, Zhuo Key Laboratory of Multifunctional Materials and Structures Ministry of Education School of Electronic Science and Engineering Xi'An Jiaotong University Shaanxi Xi'an710049 China Science and Technology on Electro-Optical Information Security Control Laboratory Tianjin300308 China School of Physics & Astronomy University of Glasgow GlasgowG12 8QQ United Kingdom MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter Department of Applied Physics Xi'An Jiaotong University Xi'an710049 China

Stronger light intensity uctuations are pursued by related applications such as optical resolution, image enhancement, and beam positioning. In this paper, an Nth-order light intensity uctuation amplifier is proposed, which was demonstrated by a four-wave mixing process with different statistical distribution coupling lights. Firstly, its amplification mechanism is revealed both theoretically and experimentally. The ratio R of statistical distributions and the degree of second-order coherence g(2)(0) of beams are used to characterize the affected modulations and the increased light intensity uctuations through the four-wave mixing process. The results show that the amplification of light intensity uctuations is caused by not only the uctuating light fields of incident coupling beams, but also the uctuating nonlinear coefficient of interaction. At last, we highlight the potentiality of applying such amplifier to other N-order nonlinear optical effects. Copyright © 2021, The Authors. All rights reserved.

关键词： Image enhancement

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Object Detection Based On Decision Level Fusion

Object Detection Based On Decision Level Fusion

引用

Chinese Automation Congress (CAC)

作者： Jun Yao Yong Zhang Fang Liu Yi-cong Liu College of Science Shengyang Ligong University Shenyang China Science and Technology on Electro-Optical Information Security Control Laboratory Tianjing China School of Automation and Electrical Engineering Shengyang Ligong University Shenyang China

Object detection is widely used in different fields. In this paper, a new object detection model of decision level fusion based on Mask R-CNN is proposed. The model fuses the infrared images and the visible images at decision-making level. It is called as IVF-Mask R-CNN. In order to improve the stability and the accuracy of the IVF-Mask R-CNN model, the partial network freeze strategy, learning rate reduction strategy and test image up-sizing strategy are used. The fuse model IVF-Mask R-CNN compensates the limitation of single imaging model of object detection. It improves the accuracy of the detection. The experimental results show that IVF-Mask R-CNN model contributes to a better object detection effect compared with the single visible detection model and the infrared detection model.

关键词： Object detection Training Feature extraction Imaging Head Convolution Classification algorithms

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Object Detection Based on Improved YOLOv3-tiny

Object Detection Based on Improved YOLOv3-tiny

引用

Chinese Automation Congress (CAC)

作者： Hua Gong Hui Li Ke Xu Yong Zhang College of Science Shengyang Ligong University Shenyang China School of Automation and Electrical Engineering Shengyang Ligong University Shenyang China Science and Technology on Electro-Optical Information Security Control Laboratory Tianjing China

Deep learning has gradually become the mainstream object detection algorithm because of its powerful feature extraction ability and adaptive ability. However, how to guarantee the accuracy and speed is still a huge challenge in the field of object detection. This paper proposes an improved YOLOv3-tiny for object detection based on the idea of feature fusion. YOLOv3-tiny is chosen as the basic network framework to ensure the identification speed. In order to improve the poor detection accuracy of YOLOv3-tiny network, feature fusion is carried out based on Feature Pyramid Network. The last DBL (Darknetconv2d_ Batch Normalization_Leaky) output of the second scale output layer is fused with the fourth DBL output of the network. And a 52$\times$ 52 scale output is added on the basis of the original network. Experiments were carried out on our dataset. The experimental results show that compared with YOLOv3-tiny, the accuracy of the improved network structure is increased by 6.3%, and the detection speed is 31.8fps, ensuring the requirements of real-time detection.

关键词： Feature extraction Object detection Real-time systems Training Convolution Microprocessors Computer architecture

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A Multitask Cascaded Convolutional Neural Network based on Full Frame Histogram Equalization for Vehicle Detection

A Multitask Cascaded Convolutional Neural Network based on F...

引用

Chinese Automation Congress

作者： Hua Gong Yong Zhang Ke Xu Fang Liu College of Science Shengyang Ligong University Shenyang China Science and Technology on Electro-Optical Information Security Control Laboratory Tianjing China

In order to improve the accuracy of vehicle detection, a Multitask Cascaded Convolutional Neural Network (MC-CNN) based on Full Frame Histogram Equalization (FFHE) algorithm is proposed. FFHE is used to enhance the image, which can solve the problem of unclear image, low contrast, low overall gray value and uneven illumination when the imaging condition is not ideal. MC-CNN locates and classifies the object in the image. The algorithm first performs FFHE operation on the test datasets. Then the region image containing a single vehicle is obtained by the object location algorithm based on Faster R-CNN. Next, the six classification (bus, microbus, minivan, sedan, SUV, and truck) results of each vehicle are obtained through the object classification algorithm based on CNN. To verify the performance of the algorithm, MC-CNN was trained on BIT-Vehicle and tested on SYIT2018-Vehicle. Compared with Faster R-CNN, the average classification accuracy of our algorithm was improved by 11.5% on SYIT2018-Vehicle dataset.

关键词： Vehicle detection MC-CNN Full frame histogram equalization

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optical Image Encryption Based on Mixed Chaotic Maps and Single-Shot Digital Holography

引用

Transactions of Tianjin University 2017年第2期23卷 184-191页

作者： Yonggang Su Chen Tang Xia Chen Biyuan Li Wenjun Xu Zhenkun Lei School of Electrical and Information Engineering Tianjin University Tianjin 300072 China Science and Technology on Electro-Optical Information Security Control Laboratory Tianjin 300308 China State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian 116024China

Random phase masks play a key role in optical image encryption schemes based on double random phase technique. In this paper, a mixed chaotic method is proposed, which can efficiently solve some weaknesses that one-dimensional (1-D) single chaotic maps encounter to generate random phase masks. Based on the chaotic random phase masks, optical image encryption and decryption are realized with a single-shot digital holographic technique. In the proposed encryption scheme, the initial value and parameters of mixed chaotic maps serve as secret keys, which is convenient for the key management and transmission. Moreover, it also possesses high resistance against statistical attack, brute-force attack, noise attack and shear attack. Simulation results and security analysis verify the validity and security of the proposed encryption scheme. © 2017, Tianjin University and Springer-Verlag Berlin Heidelberg.

关键词： Chaotic systems Geometrical optics Holography Image processing Lyapunov methods optical data processing

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Wide-range-tunable Dirac-cone band structure in a chiral-time-symmetric non-Hermitian system

引用

Physical Review A 2017年第5期96卷 052121-052121页

作者： S. Lin Z. Song School of Physics Nankai University Tianjin 300071 China Science and Technology on Electro-Optical Information Security Control Laboratory Tianjin 300308 China

We establish a connection between an arbitrary Hermitian tight-binding model with chiral (C) symmetry and its non-Hermitian counterpart with chiral-time (CT) symmetry. We show that such a non-Hermitian Hamiltonian is pseudo-Hermitian. The eigenvalues and eigenvectors of the non-Hermitian Hamiltonian can be easily obtained from those of its parent Hermitian Hamiltonian. It provides a way to generate a class of non-Hermitian models with a tunable full real band structure by means of additional imaginary potentials. We also present an illustrative example that could achieve a cone structure from the energy band of a two-layer Hermitian square lattice model.

关键词： Fermi gases Discrete symmetries Schroedinger equation

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