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Continuous-wave mid-infrared intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate

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Chinese Physics B 2008年第1期17卷 211-216页

作者：丁欣张少敏马洪梅庞明姚建铨李卓 College of Precision instrument and opto-electronics engineering Institute of Laser and Opto-Electronics Tianjin University Key Laboratory of opto-electronics Information science and Technology Ministry of Education Cooperated Institute of Nankai University and Tianjin University school of Information science and Technology Department of Opto-Electronic EngineeringBeijing Institute of Technology

This paper reports a continuous-wave （CW） mid-infrared intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate （PPLN） pumped by a diode-end-pumped CW Nd：YVO4 laser. Considering the thermal lens effects, it adopted an optical ballast lens and the near-concentric cavity for better operation. At the PPLN＇s grating period of 28.5 μm and the temperature of 140℃, the maximum idler output power of 155 mW at 3.86 μm has been achieved when the 808 nm pump power is 8.5 W, leading to an optical-to-optical conversion efficiency of 1.82%.

关键词： continuous-wave mid-infrared intracavity optical parametric oscillator periodically poled lithium niobate crystal

Influences of semiconductor laser on fibre-optic distributed disturbance sensor based on Mach-Zehnder interferometer

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Chinese Physics B 2010年第12期19卷 339-346页

作者：梁生张春熹蔺博林文台李勤钟翔李立京 school of instrument science and opto-electronics engineering Beihang University Photonics Research Centre School of Electrical and Electronic EngineeringNanyang Technological University50 Nanyang Avenue639798Singapore

This paper investigates the influences of a semiconductor laser with narrow linewidth on a fibre-optic distributed disturbance sensor based on Mach-Zehnder interferometer. It establishes an effective numerical model to describe the noises and linewidth of a semiconductor laser, taking into account their correlations. Simulation shows that frequency noise has great influences on location errors and their relationship is numerically investigated. Accordingly, there is need to determine the linewidth of the laser less than a threshold and obtain the least location errors. Furthermore, experiments are performed by a sensor prototype using three semiconductor lasers with different linewidths, respectively, with polarization maintaining optical fibres and couplers to eliminate the polarization induced noises and fading. The agreement of simulation with experimental results means that the proposed numerical model can make a comprehensive description of the noise behaviour of a semiconductor laser. The conclusion is useful for choosing a laser source for fibre-optic distributed disturbance sensor to achieve optimized location accuracy. What is more, the proposed numerical model can be widely used for analysing influences of semiconductor lasers on other sensing, communication and optical signal processing systems.

关键词： fibre-optic distributed sensor semiconductor laser narrow linewidth laser fibre-optic interferometric sensor

Spatial and temporal evolution of electromagnetic pulses from solid target irradiated with multi-hundred-terawatt laser pulse inside target chamber

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Plasma science and Technology 2024年第2期26卷 62-69页

作者：何强友邓志刚张智猛夏亚东张博孟令彪贺书凯黄华杨雷刘红杰范伟林晨周维民李廷帅颜学庆 State Key Laboratory of Nuclear Physics and Technology and Key Laboratory of HEDP of the Ministry of EducationCAPTPeking UniversityBeijing 100871People's Republic of China science and Technology on Plasma Physics Laboratory Research Center of Laser FusionChina Academy of Engineering PhysicsMianyang 621900People's Republic of China school of Materials and Energy University of Electronic Science and Technology of ChinaChengdu 611731People's Republic of China Beijing Laser Acceleration Innovation Center Beijing 101400People's Republic of China

Giant electromagnetic pulses(EMPs) induced by high-power laser irradiating solid targets interfere with various experimental diagnoses and even damage equipment,so unveiling the evolution of EMPs inside the laser chamber is crucial for designing effective EMP *** this work,the transmission characteristics of EMPs as a function of distances from the target chamber center(TCC) are studied using B-dot *** mean EMP amplitude generated by picosecond laser-target interaction reaches 561 kV m^(-1),357 kV m^(-1),395 kV m^(-1),and 341 kV m^(-1)at 0.32 m,0.53 m,0.76 m,and 1 m from TCC,which decreases dramatically from 0.32 m to 0.53 ***,it shows a fluctuation from 0.53 m to 1 *** temporal features of EMPs indicate that time-domain EMP signals near the target chamber wall have a wider full width at half maximum compared to that close to TCC,mainly due to the echo oscillation of electromagnetic waves inside the target chamber based on simulation and *** conclusions of this study will provide a new approach to mitigate strong electromagnetic pulses by decreasing the echo oscillation of electromagnetic waves inside the target chamber during laser coupling with targets.

关键词： target electromagnetic pulses spatial distribution

Broadband Terahertz Transmission Modulation Based on Hybrid Graphene-Metal Metamaterial

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Journal of electronic science and Technology 2018年第2期16卷 98-104页

作者： Lan-Ju Liang Zhang Zhang Xin Yan Xin Ding De-Quan Wei Qi-Li Yang Zhen-Hua Li Jian-Quan Yao College of Precision instrument and opto-electronics engineering Tianjin UniversityTianjin 300072 school of opto-electronic engineering Zaozhuang UniversityZaozhuang 277160

A novel patterned metamaterial,composed of graphene layer and metal periodic array of split ring resonators （SRRs） and cross-shapedresonators （CSRs）, with broadband terahertz （THz） wave modulation was proposed and theoretically studied. It demonstrated that a broad passband high transmission of over 96.1% in the frequency range from 1.02 THz to 1.66 THz and two narrow band resonance frequencies f1 and f2 could be generated. The modulation depth of transmission was 29.2% when the graphene layer was covered on the metal metamaterial surface, and the modulation depth could be further increased by increasing the Fermi energy of graphene layer and reached approximately 79.5% at 1.0 eV in a broadband THz frequency range. The resonance frequencies of f1 and f2 were blue-shifted, and their modulation depths reached about 63.2% and 18%, respectively. These results show that the ultrathin graphene-metal metamaterial exhibits potential to achieve highperformance active THz devices and may offer widespread applications.

关键词： Graphene metamaterial modulator terahertz

Development of an optical probe to measure the flattened area of ocular cornea

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Chinese Optics Letters 2010年第1期8卷 103-106页

作者：张学勇马建国卢荣胜李义宝唐震刘果红 school of instrument science and opto-electronic engineering Hefei University of Technology Department of Mathematics and Physics Anhui University of Architecture Department of Physics Huainan Normal University

The optical probe in tonometers is a key component in measuring the flattened diameter or area of the ocular cornea. A new kind of optical probe for the direct measurement of the flattened area of the ocular cornea is presented. The optical probe uses the cone prism with a modulating flake of light intensity as its measuring body. The test results on simulated eyeballs with different radii of curvature of the ocular cornea show that there is a linear relation between the flattened area of the ocular cornea and the normalized current. The optical probe, which is more compact compared with existing optical probes and easily configured with its coaxiality of optical parts, may be an excellent probe for constructing a low-cost, miniaturized applanation tonometer.

关键词： Optics Physics

Wearable multichannel-active pressurized pulse sensing platform Yunlong

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Microsystems & Nanoengineering 2024年第3期10卷 283-292页

作者： Zhao Qingxia Sun Shixuan Mei Libo Gao Xikuan Zhang Zekun Yang Xueli Nan Haiyan Zhang Chenyang Xue Junyang Li Pen-Tung Sah Institute of Micro-Nano science and Technology Xiamen University361102 XiamenChina Discipline of Intelligent instrument and Equipment Xiamen University361102 XiamenChina Department of electronic engineering Ocean University of China266000 QingdaoChina school of Automation and Software engineering Shanxi University030006 TaiyuanChina Innovation Laboratory for sciences and Technologies of Energy Materials of Fujian Province(IKKEM) 361005 XiamenChina Key Laboratory of instrumentation science and Dynamic Measurement Ministry of Education North University of China030051 TaiyuanChina science and Technology on Vacuum Technology and Physics Laboratory Lanzhou Institute of PhysicsChinese Academy of Space Technology730000 LanzhouChina

With the modernization of traditional Chinese medicine(TCM),creating devices to digitalize aspects of pulse diagnosis has proved to be *** currently available pulse detection devices usually rely on external pressure devices,which are either bulky or poorly integrated,hindering their practical *** this work,we propose an innovative wearable active pressure three-channel pulse monitoring device based on TCM pulse diagnosis *** combines a flexible pressure sensor array,flexible airbag array,active pressure control unit,advanced machine learning approach,and a companion mobile application for human–computer *** to the high sensitivity(460.1 kPa^(−1)),high linearity(R^(2)>0.999)and flexibility of the flexible pressure sensors,the device can accurately simulate finger pressure to collect pulse waves(Cun,Guan,and Chi)at different external pressures on the *** addition,by measuring the change in pulse wave amplitude at different pressures,an individual’s blood pressure status can be successfully *** enables truly wearable,actively pressurized,continuous wireless dynamic monitoring of wrist pulse *** innovative and integrated design of this pulse monitoring platform could provide a new paradigm for digitizing aspects of TCM and other smart healthcare systems.

关键词： pulse diagnosis enable

A novel nondestructive detection approach for seed cotton lint percentage using deep learning

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Journal of Cotton Research 2024年第2期7卷 148-162页

作者： Geng Lijie YAN Pengji JI Zhikun SONG Chunyu SONG Shuaifei ZHANG Ruiliang ZHANG Zhifeng ZHAI Yusheng JIANG Liying YANG Kun school of electronic and Information Henan Key Laboratory of Magnetoelectronic Information Functional MaterialsZhengzhou University of Light IndustryZhengzhou 450002HenanChina

Background The lint percentage of seed cotton is one of the most important parameters for evaluating seed cotton quality and affects its *** traditional measuring method of lint percentage is labor-intensive and time-consuming;thus,an efficient and accurate measurement method is *** recent years,classification-based deep learning and computer vision have shown promise in solving various classification *** In this study,we propose a new approach for detecting the lint percentage using MobileNetV2 and transfer *** model is deployed on a lint percentage detection instrument,which can rapidly and accurately determine the lint percentage of seed *** evaluated the performance of the proposed approach using a dataset comprising 66924 seed cotton images from different regions of *** results of the experiments showed that the model with transfer learning achieved an average classification accuracy of 98.43%,with an average precision of 94.97%,an average recall of 95.26%,and an average F1-score of 95.20%.Furthermore,the proposed classification model achieved an average accuracy of 97.22%in calculating the lint percentage,showing no significant difference from the performance of experts(independent-sample t-test,t=0.019,P=0.860).Conclusion This study demonstrated the effectiveness of the MobileNetV2 model and transfer learning in calculating the lint percentage of seed *** proposed approach is a promising alternative to traditional methods,providing a rapid and accurate solution for the industry.

关键词： Neural network MobileNetV2 Nondestructive detection Smart agriculture Seed cotton lint percentage

Materials and applications of bioresorbable electronics

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Journal of Semiconductors 2018年第1期39卷 38-47页

作者： Xian Huang Biomedical engineering School of Precision Instrument and Opto-Electronic Engineering Tianjin University

Bioresorbable electronics is a new type of electronics technology that can potentially lead to biodegradable and dissolvable electronic devices to replace current built-to-last circuits predominantly used in implantable devices and consumer electronics. Such devices dissolve in an aqueous environment in time periods from seconds to months, and generate biological safe products. This paper reviews materials, fabrication techniques, and applications of bioresorbable electronics, and aims to inspire more revolutionary bioresorbable systems that can generate broader social and economic impact. Existing challenges and potential solutions in developing bioresorbable electronics have also been presented to arouse more joint research efforts in this field to build systematic technology framework.

关键词： bioresorbable electronics bioresorbable materials flexible electronics implantable devices

Effect of optical pumping on the momentum relaxation time of graphene in the terahertz range

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Chinese Physics B 2013年第9期22卷 579-582页

作者：左志高王平凌福日刘劲松姚建铨 Wuhan National Laboratory for optoelectronics Huazhong University of Science and Technology school of Optical and electronic Information Huazhong University of Science and Technology College of Precision instrument and opto-electronics engineering Tianjin University

The momentum relaxation time of a photoexcited graphene in the THz frequency range has been studied by using terabertz time domain spectroscopy under optical pumping at room temperature. It is found that the momentum relaxation time of the graphene as a function of the optical pumping intensity exhibits a threshold behavior. The features of the momentum relaxation time as a function of the optical pumping intensity are also investigated. The results are useful for understanding the basic underlying physics of graphene scattering as well as finding the possible applications in carbon- based electronics.

关键词： graphene momentum relaxation time optical pumping terahertz