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Preparation and optimization of freestanding GaN using low-temperature GaN layer

Frontiers of Materials Science 2019年第3期13卷 314-322页

作者： Yuan TIAN Yongliang SHAO Xiaopeng HAO Yongzhong WU Lei ZHANG Yuanbin DAI Qin HUO Baoguo ZHANG Haixiao HU State Key Lab of Crystal Materials Shandong UniversityJinan 250100China Key Lab of Advaneed Transducers and Intelligent Control System(Ministry of Education) Taiyuan University of TechnologyTaiyuan 030024China College of Physics and Optoelectronics Taiyuan University of TechnologyTaiyuan 030024China

In this work,a method to acquire freestanding GaN by using low temperature(LT)-GaN layer was put *** obtain porous structure and increase the crystallinity,LT-GaN layers were annealed at high *** morphology of LTGaN layers with different thickness and annealing temperature before and after annealing was *** of GaN films using different LT-GaN layers was made to acquire optimal LT-GaN *** to HRXRD and Raman results,GaN grown on 800 nm LT-GaN layer which was annealed at 1090℃ has good crystal quality and small *** GaN film was successfully separated from the substrate after cooling *** self-separation mechanism of this method was ***-sectional EBSD mapping measurements were carried out to investigate the effect of LT-buffer layer on improvement of crystal quality and stress *** optical property of the obtained freestanding GaN film was also determined by PL measurement.

关键词： GaN self-separation low-temperature annealing

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Performance analysis of several wavelets in pipeline leak detection and location using Colpitts chaotic signal

Performance analysis of several wavelets in pipeline leak de...

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2018 International Conference on Electronics Technology, ICET 2018

作者： Zhang, Zhaoxia Cui, Gongzhe Xue, Xiaozhen Yang, Lingzhen Wang, Juanfen Xue, Pingping College of Physics and Optoelectronics Taiyuan University of Technology Key Laboratory of Advanced Transducers and Intelligent Control System Ministry of Education Taiyuan Shanxi030024 China

ISBN: (纸本)9781538657522

In this paper, the performance of wavelet transform on the detection and location of pipeline leak are explored. The effects of three wavelets on different thresholds and different decomposition layers are studied. Firstly, the UWB(Ultra Wideband) chaotic signal generated by Colpittscircuit is used as the signal detection signal, and the leak point of the pipeline is detected and located by analyzing the cross-correlation coefficient between the detection signal and the echo signal after the pipeline reflection. Because there are some questions such as how to choose the optimal threshold function, wavelets and optimal number of decomposed layers, three wavelet thresholds (hard threshold, soft threshold and given threshold)which has different signal-To-noise ratio (5dB, 10dB, 30dB) are used in signal threshold denoising. The paper explores the denoising effects of three wavelets(sym4, db4, Haar) after three, four and five wavelet decomposition, and finally gets the optimal threshold method, wavelet function and decomposition layer. This is important to achieve high-precision detection and location of water pipeline leak. © 2018 IEEE.

关键词： Leak detection

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Ultra-wide tuning single channel filter based on one-dimensional photonic crystal with an air cavity

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Journal of Semiconductors 2017年第2期38卷 26-30页

作者： Xiaodan Zhao Yibiao Yang Zhihui Chen Yuncai Wang Hongming Fei Xiao Deng Department of Physics and Optoelectronics Taiyuan University of Technology Taiyuan 030024 China Key Laboratory of Advanced Transducers and Intelligent Control System Taiyuan University of TechnologyMinistry of Education Taiyuan 030024 China

By inserting an air cavity into a one-dimensional photonic crystal of LiF/GaSb, a tunable filter covering the whole visible range is proposed. Following consideration of the dispersion of the materials, through modulating the thickness of the air cavity, we demonstrate that a single resonant peak can shift from 416.1 to 667.3 nm in the band gap at normal incidence by means of the transfer matrix method. The research also shows that the transmittance of the channel can be maximized when the number of periodic Li F/Ga Sb layers on one side of the air defect layer is equal to that of the other side. When adding a period to both sides respectively, the full width at half maximum of the defect mode is reduced by one order of magnitude. This structure will provide a promising approach to fabricate practical tunable filters in the visible region with ultra-wide tuning range.

关键词： photonic crystal filters transfer matrix method single resonant peak ultra-wide tuning range mechanical modulation

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Signal Fading Suppression in Ф-OTDR Based on EMD-GAN

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Zhongguo Jiguang/Chinese Journal of Lasers 2025年第6期52卷

作者： Liu, Xin Liu, Zhihua Zhou, Xiaoxu Wang, Yu Bai, Qing Jin, Baoquan College of Electronic Information and Optical Engineering Taiyuan University of Technology Shanxi Taiyuan030024 China Shanxi Transportation Technology Research & Development Co. Ltd. Shanxi Taiyuan030600 China Shanxi Intelligent Transportation Laboratory Co. Ltd. Shanxi Taiyuan030036 China Key Laboratory of Advanced Transducers and Intelligent Control Systems Ministry of Education Taiyuan University of Technology Shanxi Taiyuan030024 China

Objective In phase-sensitive optical time-domain reflectometers (Ф‑OTDRs), coherent and polarization fading caused by inherent destructive interference and polarization mismatch, affect phase restoration performance. Traditional signal fading suppression methods typically require additional hardware structures, which increases system complexity and cost. Moreover, vibration signals are non- stationary with complex frequency components, which further increases the fading suppression challenge. Therefore, it is of paramount significance to investigate a novel signal fading suppression method to achieve accurate phase reconstruction on the simplest structure in scientific research and engineering applications. Methods In this study, the random signal fading process in Ф- OTDR is analyzed, and it is confirmed that the fading point phase is a random noise value that follows uniform distribution. Using the empirical mode decomposition (EMD) algorithm, phase noise including phase accumulation noise and laser frequency drift is filtered out and phase information modulated by external vibration is extracted. The extracted phase data are subsequently organized into a two-dimensional space-time map, which are input into a generative adversarial network (GAN) to realize the repair of the fading data. The GAN training dataset, which is generated using software simulation, contains a total of 12000 images including the phase spectra of sinusoidal, square, and triangular wave vibration signals, Gaussian pulse vibration signal, and random vibration signal. Results and Discussions Experiments are designed as follows. The total length of the sensing fiber is 10.12 km, which is connected by three sections of single-mode fibers of 4.17, 1.92, and 3.95 km in length, respectively. A piezoelectric ceramic (PZT) is connected between each section of fiber and driven by the signal generator to produce the required vibration signal. Phase demodulation is performed at two vibration positions (

关键词： Single mode fibers

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controllable four-wave mixing response in a dual-cavity hybrid optomechanical system

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Chinese Physics B 2021年第5期30卷 406-411页

作者： Lei Shang Bin Chen Li-Li Xing Jian-Bin Chen Hai-Bin Xue Kang-Xian Guo Department of Physics College of Physics and OptoelectronicsTaiyuan University of TechnologyTaiyuan 030024China Key Laboratory of Advanced Transducers and Intelligent Control System Ministry of Education and Shanxi ProvinceTaiyuan 030024China Department of Physics School of Physics and Material ScienceGuangzhou UniversityGuangzhou 510006China

We systematically investigate the four-wave mixing(FWM)spectrum in a dual-cavity hybrid optomechanical system,which is made up of one optical cavity with an ensemble of two-level atoms and another with a mechanical *** this work,we propose that the hybrid dual-cavity optomechanical system can be employed as a highly sensitive mass sensor due to the fact that the FWM spectrum generated in this system has a narrow spectral width and the intensity of the FWM can be easily tuned by controlling the coupling strength(cavity-cavity,atom-cavity).More fascinatingly,the dual-cavity hybrid optomechanical system can also be used as an all-optical switch in view of the easy on/off control of FWM signals by adjusting the atom-pump detuning to be positive or *** proposed schemes have great potential applications in quantum information processing and highly sensitive detection.

关键词： four-wave mixing dual-cavity optomechanical system atomic ensemble

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Electromagnetic-acoustic Beam Compressor by Double-physical-fields Null Medium

Electromagnetic-acoustic Beam Compressor by Double-physical-...

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2024 Photonics and Electromagnetics Research Symposium, PIERS 2024

作者： Sun, Ran Sun, Fei Liu, Yichao Zhang, Zeyu Yang, Chao Taiyuan University of Technology Key Lab of Advanced Transducers and Intelligent Control System Ministry of Education and Shanxi Province College of Electronic Information and Optical Engineering Taiyuan030024 China

ISBN: (纸本)9798350375909

In this study, double-physical-fields null medium, i.e., a subwavelength air channels surrounded by a carefully arranged metal plates, is utilized to design an electromagnetic-acoustic beam compressor capable of simultaneously compressing electromagnetic waves and acoustic waves. Numerical simulation results verify its ability to simultaneously produce the expected compression ratios for both electromagnetic waves and acoustic waves. Moreover, the compression ratio precisely matches the geometric size ratio of the input and output planes of the compressor. This work may have potential applications in electromagnetic-acoustic coupling systems and electromagnetic-acoustic processing/detection. © 2024 IEEE.

关键词： Acoustic waves

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A Dual-function Quasi-static Magnetic Device with Cloaking and Concentrating Functions Simultaneously

A Dual-function Quasi-static Magnetic Device with Cloaking a...

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2024 Photonics and Electromagnetics Research Symposium, PIERS 2024

作者： Chen, Hanchuan Liu, Yichao Sun, Fei Taiyuan University of Technology Key Lab of Advanced Transducers and Intelligent Control System Ministry of Education and Shanxi Province College of Electronic Information and Optical Engineering Taiyuan030024 China

ISBN: (纸本)9798350375909

In previous study, many single-function static/quasi-static magnetic devices, such as cloak and concentrator, have been designed base on transformation optics. However, few have explored devices capable of simultaneously generating two different functions on the static/quasi-static magnetic field. In this study, we propose a dual-function quasi-static magnetic device, which can create a concealed region and concentrated region for quasi-static magnetic field simultaneously. The dual-function quasi-static magnetic device is designed via twice extreme spatial stretching transformation and magnetic null medium, which can be realized by using arrays of superconductors and ferromagnetic materials in specific arrangement. The simulated results verify the performance of the proposed dual-function quasi-static magnetic device, which can simultaneously achieve cloaking and concentrating effect for the magnetic field from DC to 1000 Hz. The quasi-static magnetic field can be enhanced 9 times than the background magnetic field when the side lengths of the internal square pillar and external square pillar of the proposed structure are selected as a = 10 mm and b = 90 mm, respectively. Moreover, the concentrating ratio obtained from theoretical calculation fits well with the results obtained through numerical simulation. The dual-function quasi-static magnetic device designed in this study may have essential application in medical testing for special occasions. © 2024 IEEE.

关键词： Wigglers

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Parallel Implementation of the Non-Overlapping Template Matching Test Using CUDA

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China Communications 2020年第8期17卷 234-241页

作者： Kaikai Li Jianguo Zhang Pu Li Anbang Wang Yuncai Wang Key Lab of Advanced Transducers and Intelligent Control System(Taiyuan University of Technology) Ministry of Education&Shanxi ProvinceTaiyuan 030024China College of Information Engineering Guangdong University of TechnologyGuangzhou 510006China Guangdong Provincial Key Laboratory of Photonics Information Technology Guangdong University of TechnologyGuangzhou 510006China

NIST(National Institute of Standards and Technology) statistical test recognized as the most authoritative is widely used in verifying the randomness of binary sequences. The Non-overlapping Template Matching Test as the 7 th test of the NIST Test Suit is remarkably time consuming and the slow performance is one of the major hurdles in the testing process. In this paper, we present an efficient bit-parallel matching algorithm and segmented scan-based strategy for execution on Graphics Processing Unit(GPU) using NVIDIA Compute Unified Device Architecture(CUDA). Experimental results show the significant performance improvement of the parallelized Non-overlapping Template Matching Test, the running speed is 483 times faster than the original NIST implementation without attenuating the test result accuracy.

关键词： random numbers CUDA non-overlapping template matching test parallel implementation NIST test

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Realizing mode conversion and optical diode effect by coupling photonic crystal waveguides with cavity

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Chinese Physics B 2015年第9期24卷 284-288页

作者：叶寒张金倩楠俞重远王东林陈智辉 State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and Telecommunications Theoretical Condensed Matter Physics and Computational Materials Physics Laboratory School of PhysicsUniversity of Chinese Academy of Sciences Key Laboratory of Advanced Transducers and Intelligent Control System Ministry of Education and Shanxi ProvinceTaiyuan University of Technology

We propose a novel two-dimensional photonic crystal structure consisting of two line defect waveguides and a cavity to realize mode conversion based on the coupling effect. The W1/cavity/W2 structure breaks the spatial symmetry and successfully converts the even（odd） mode to the odd（even） mode in the W2 waveguide during the forward（backward）transmission. When considering the incidence of only the even mode, the optical diode effect emerges and achieves approximate 35 d B unidirectionality at the resonant frequency. Moreover, owing to the narrow bandpass feature and the flexibility of the tuning cavity, utilization of the proposed structure as a wavelength filter is demonstrated in a device with a Y-branch splitter. Here, we provide a heuristic design for a mode converter, optical diode, and wavelength filter derived from the coupling effect between a cavity and adjacent waveguides, and expect that the proposed structure can be applied as a building block in future all-optical integrated circuits.

关键词： mode conversion optical diode photonic crystal

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Fusion modeling of the hot rolling strip width

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Journal of Computational Information systems 2014年第12期10卷 5373-5380页

作者： Tian, Jianyan Wang, Fang Qiu, Huadong Li, Wenting College of Information Engineering Taiyuan University of Technology Taiyuan 030024 China Key Lab. of Advanced Transducers and Intelligent Control Syst. at Taiyuan Univ. of Technol. Ministry of Education Taiyuan 030024 China

By organically integrating the computation formulas of hot rolling strip width mechanism model with the intelligent modeling technique, this paper proposes an intelligent fusion modeling method for a hot rolling strip width model. Due to the relations between the variations of hot rolling strip width and factors such as the chemical composition of the slabs, side compression of vertical rollers, thickness compression ratios, plate temperature, velocity and strain, and also the distinct influences by these factors mentioned afore, this paper adopts a neural network based on the improved particle swarm optimization to adjust parameters in the width mechanism model. It aims to give the mechanism model some level of self-learning and adaptive abilities, as to improve the model accuracy, broaden the range of applications, and also ensure modeling speed. In addition, in order to better control the head and tail shapes of the strip, an improvement about short stroke control has been made to the head and tail width model. Practical applications at a steelworks indicate that this method is feasible and effective by reducing width fluctuations of finished strips, raising steel yield rates and achieving favorable economical benefits. 1553-9105/Copyright © 2014 Binary Information Press.

关键词： Particle swarm optimization (PSO)

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