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Harmonic Mode-Locked Ytterbium-Doped Fibre Ring Laser

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Chinese Physics Letters 2007年第4期24卷 944-946页

作者：杨玲珍王云才陈国夫王屹山赵卫 Department of Physics College of Science Taiyuan University of Technology Shanxi 030024 State Key laboratory of Transient Optics Technology Xi'an Institute of Optics and Precision Mechanics Chinese Academy of Sciences Xi'an 710068

We demonstrate a harmonic mode-locked ytterbium-doped fibre ring laser, which consists of a polarization-sensitive isolator, two polarization controllers, two 976nm laser diodes as the pump source and a two-segment ytterbium-doped fibre. Utilizing an additive pulse mode-locked technique based on nonlinear polarization evolution, the ytterbium-doped fibre laser can operate in mode-locked state by adjusting the position of polarization controllers. The cavity fundamental repetition rate is 23.78 MHz. We also observe the second- and third-harmonic mode locking in the normal dispersion region, and their repetition rates are 47.66 MHz and 71.56 MHz, respectively. Over-driving of the saturable absorber in the harmonic mode-locking pulse is analysed and discussed in detail.

关键词： TI-SAPPHIRE LASER CHAOTIC BEHAVIOR GENERATION AMPLIFIER GHZ

All-Solid-State Near-Infrared and Blue Femtosecond Laser System

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Chinese Physics Letters 2002年第2期19卷 203-204页

作者： Bai Jin-Tao Chen Guo-Fu Huang Sheng-Hong Yu Lian-Jun Wang Yi-Shan Institute of Photonics and Photo-technology Northwest University Xi'an 710069 Provincial Key laboratory of Photoelectronic Technology Northwest University Xi'an 710069 State Key laboratory of Transient Optics and Technology Xi'an Institute of Optics and Precision Mechanics Chinese Academy of Sciences Xi'an 710068

We investigate an all-solid-state continuous wave (cw) green (532nm), femtosecond near-infrared (823.1nm) and blue (402nm) laser system which is pumped by a diode-laser-pumped intracavity frequency-doubled and all-self-structuring cw Nd:YVO4/KTP 532nm green laser. The cavity parameters of the Nd:YVO4/KTP laser have been optimized and the maximum 5.6W TEM00 green laser is obtained at a 22W pump power with an optical-optical conversion efficiency of 25.5%. A Ti:Sapphire laser and nonlinear second-harmonic generation by a crystal BBO is used to obtain different wavelengths. A femtosecond laser with an average output power of 300mW at 823.1nm and 73mW at 402nm is obtained when the green pump power is 2.5W. The spectral full width at half maximum are 32.3nm and 5.1nm, which can sustain the pulses of 22fs and 33.3fs, respectively.

关键词： Femtosecond lasers

Emerging miniaturized energy storage devices for microsystem applications:from design to integration

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International Journal of Extreme manufacturing 2020年第4期2卷 1-28页

作者： Huaizhi Liu Guanhua Zhang Xin Zheng Fengjun Chen Huigao Duan State Key laboratory of Advanced Design and manufacturing for Vehicle Body College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082People’s Republic of China

The rapid progress of micro/nanoelectronic systems and miniaturized portable devices has tremendously increased the urgent demands for miniaturized and integrated power *** energy storage devices(MESDs),with their excellent properties and additional intelligent functions,are considered to be the preferable energy supplies for uninterrupted powering of *** this review,we aim to provide a comprehensive overview of the background,fundamentals,device configurations,manufacturing processes,and typical applications of MESDs,including their recent *** attention is paid to advanced device configurations,such as two-dimensional(2D)stacked,2D planar interdigital,2D arbitrary-shaped,three-dimensional planar,and wire-shaped structures,and their corresponding manufacturing strategies,such as printing,scribing,and masking ***,recent developments in MESDs,including microbatteries and microsupercapacitors,as well as microhybrid metal ion capacitors,are systematically summarized.A series of on-chip microsystems,created by integrating functional MESDs,are also ***,the remaining challenges and future research scope on MESDs are discussed.

关键词： microsystems miniaturized energy storage devices microbatteries microsupercapacitors microhybrid metal ion capacitors

Effect of ultrasonic power and casting speed on solidification structure of 7050 aluminum alloy ingot in ultrasonic field

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Journal of Central South University 2010年第3期17卷 431-436页

作者：张立华余军张晓明 Key laboratory of Modern Complex Equipment Design and Extreme manufacturing Ministry of Education Central South University School of Mechanical and Electrical Engineering Central South University

With the experiment and finite element simulation, the influences of power ultrasonic on the solidification structure of 7050 aluminum alloy ingot in semi-continuous casting were researched, and the effects of casting speed on solidification structure in ultrasonic field were also analyzed. The experiment and simulation results show that the solidification structure of the ingot is homogeneously distributed, and its grain size is obviously refined at ultrasonic power of 240 W. The average grain sizes, which can be seen from the Leica microscope, are less than 100 μm. When the casting speed is 45-50 mm/min, the best grain refinement is obtained.

关键词： 7050铝合金半连续铸造合金铸锭超声功率凝固组织凝固速度场结构平均晶粒尺寸

Army-Materiel-System-Analysis-Activity Maturity Projection Model Based on a Subsystem Stein Estimator

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Journal of Donghua University(English Edition) 2020年第5期37卷 436-445页

作者：李中生范晋伟潘日 Beijing Key laboratory of Advanced manufacturing Technology Beijing University of TechnologyBeijing 100124China

A reliability-growth test is often used to assess complex systems under ***-growth models are usually used to quantify the achievable reliability indices and predict the expected reliability *** Crow army-materiel-system-analysis-activity(Crow-AMSAA)projection model and the AMSAA maturity projection(AMPM)-Stein model are suitable for modelling delayed corrective *** AMPM-Stein model,which involves more failure data and requires limited assumptions,is more robust than the Crow-AMSAA projection ***,the rationality of the Stein factor introduced in the AMPM-Stein model has always been *** AMPM-Stein extended projection model,derived from data regrouping based on similar failure mechanisms,is presented to alleviate the *** study demonstrated that the proposed model performed well,the prediction results were credible,and the robustness of the proposed model was ***,the Stein-shrinkage factors,which are derived from components with similar inherent failure mechanisms,are easier to understand and accept in the field of *** example shows that the proposed model is more suitable and accurate than the Crow-AMSAA model and the AMPM-Stein model,by comparing the projection values based on the failure data of the previous phases with the actual values of the current *** study provides a technical basis for extensive applications of the proposed model.

关键词： reliability projection army-materiel-system-analysis-activity maturity projection model(AMPM) Stein estimator subsystem

Influence of welding parameters on temperature field characteristics during laser welding of TA15 by infrared thermography

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China Welding 2018年第2期27卷 1-12页

作者：段爱琴巩水利黄松 Science and Technology on Power Beam Process laboratory Beijing aviation manufacturing engineering research institute

Using an infrared thermographic technique, the temperature field during laser welding of TA15 is quantitatively measured and investigated. The ilffluenee of two welding parameters on the weld temperature distribution is analyzed and the meehanisnl is discussed. New conclusions are drawn that are different from conventional weld temperature distributions. For the face of the weld, changes in welding speed induce changes in the temperature distribution because of different heat inputs and the cooling effect. Sinfilar temperature features in the welds are observed for all speeds, which exhibit a relatively low temperature area below 1 500 ℃ between the high temperature area in the position of laser incidence and the sub-high temperature area at the end of the molten pool. For the ilffluenee of laser power on the face of the weld, the temperature on the weld is higher for P = 2.8 kW compared to P = 2.0 kW, especially the temperature in the sub-high temperature area. However, for the temperature field of the back of the weld, the ilffluenee of welding speeds is quite different compared to the results for the face of the weld. The highest temperature does not locate in the keyhole area, but instead in the middle of the molten pool. And there are different temperature features at different speeds. When v = 6 m/min, the temperature field is like a uniform color belt and the temperature along the center of the weld fluctuates between 300 and 450 ℃. When v = 4 m/rain, the transient temperature distribution is not uniform and is unstable at different times. However, for v = 2.4 m/rain and lower speeds, the temperature field becomes stable. The ilffluenee of laser power on the back of the weld temperature field is more complex. The measured temperature does not increase with increasing laser power, which seems to eolffliet with the conventional thermal conduction theory-. This may be related with the characteristics of the keyhole area.

关键词： YAG laser welding temperature field infrared thennography Ti alloy

Microwave Induced Ethanol Bath Bonding for PMMA Microfluidic Device

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Journal of Harbin Institute of Technology(New Series) 2016年第2期23卷 40-45页

作者： Xiaowei Han Xiaowei Liu Li Tian He Zhang Cuicui Zhuang Key laboratory of Micro-systems and Micro-structures manufacturing Ministry of EducationHarbin Institute of Technology

High bonding strength,low deformation and convenient procedure are all very important aspects in the microfluidic device fabrication process. In this paper,an improved microwave induced bonding technology is proposed to fabricate microfluidic device based on methyl methacrylate( PMMA). This method employs pure ethanol as the bonding assisted solvent. The ethanol not only acts as the microwave absorbing material,but also works as the organic solvent in bath. The presented research work has shown that the bonding process can be completed in less than 45 s. Furthermore,the convenient bonding only applies microwave oven,beakers and binder clips. Then,we discuss effects of microwave power,bonding time on bonding strength and deformation of microstructures on PMMA microfluidic device. Finally,a 4 layers micro-mixer has been fabricated using the proposed bonding technique which includes 15 trapezoid micro-channels,9 T-type mix units and an X-type mix unit. Experimental results show that the proposed bonding method have some advantages compared with several traditional bonding technologies,such as hot pressing bonding,ultrasonic bonding and solvent assisted bonding methods in respect of bonding strength,deformation and bonding process. The presented work would be helpful for low coat mass production of multilayer polymer microfluidic devices in lab.

关键词： PMMA microwave bonding multilayer microfluidic device micro-mixer

Unveiling the parasitic-reaction-driven surface reconstruction in Ni-rich cathode and the electrochemical role of Li_(2)CO_(3)

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Journal of Energy Chemistry 2023年第10期85卷 126-136,I0006页

作者： Jiyu Cai Zhenzhen Yang Xinwei Zhou Bingning Wang Ana Suzana Jianming Bai Chen Liao Yuzi Liu Yanbin Chen Shunlin Song Xuequan Zhang Li Wang Xiangming He Xiangbo Meng Niloofar Karami Baasit Ali Shaik Sulaiman Natasha A.Chernova Shailesh Upreti Brad Prevel Feng Wang Zonghai Chen Chemical Sciences and Engineering Division Argonne National Laboratory9700 South Cass AvenueLemontIL 60439USA Center for Nanoscale Materials Argonne National Laboratory9700 South Cass AvenueLemontIL 60439USA Condensed Matter Physics and Materials Science Department Brookhaven National LaboratoryUptonNY 11973USA Energy and Photon Sciences Directorate Brookhaven National LaboratoryUptonNY 11973USA Beijing Easprint Material Technology Co.Ltd. Beijing 100160China Institute of Nuclear and New Energy Technology Tsinghua UniversityBeijing 100084China Department of Mechanical Engineering University of ArkansasFayettevilleAR 72701USA Charge CCCV(C4V) 45 Murray Hill RoadCenter of ExcellenceBinghamton UniversityVestalNY 13850USA Primet precision Materials 950 Danby RoadIthacaNY 14850USA Applied Materials Division Argonne National Labo

Nickel-rich transition-metal oxides are widely regarded as promising cathode materials for high-energydensity lithium-ion batteries for emerging electric vehicles. However, achieving high energy density in Ni-rich cathodes is accompanied by substantial safety and cycle-life obstacles. The major issues of Ni-rich cathodes at high working potentials are originated from the unstable cathode-electrolyte interface, while the underlying mechanism of parasitic reactions towards surface reconstructions of cathode materials is not well understood. In this work, we controlled the Li_(2)CO_(3) impurity content on LiNi_(0.83)Mn_(0.1)Co_(0.07)O_(2) cathodes using air, tank-air, and O_(2) synthesis environments. Home-built high-precision leakage current and on-line electrochemical mass spectroscopy experiments verify that Li_(2)CO_(3) impurity is a significant promoter of parasitic reactions on Ni-rich cathodes. The rate of parasitic reactions is strongly correlated to Li_(2)CO_(3) content and severe performance deterioration of Ni83 *** post-mortem characterizations via high-resolution transition electron microscope and X-ray photoelectron spectroscopy depth profiles reveal that parasitic reactions promote more Ni reduction and O deficiency and even rock-salt phase transformation at the surface of cathode materials. Our observation suggests that surface reconstructions have a strong affiliation to parasitic reactions that create chemically acidic environment to etch away the lattice oxygen and offer the electrical charge to reduce the valence state of transition metal. Thus, this study advances our understanding on surface reconstructions of Nirich cathodes and prepares us for searching for rational strategies.

关键词： Ni-rich cathodes Surface reconstructions Phase transformation Parasitic reactions Li_(2)CO_(3)

A 1.7-ps pulse mode-locked Yb^(3+):Sc_2SiO_5 laser with a reflective graphene oxide saturable absorber

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Chinese Physics B 2015年第1期24卷 287-289页

作者：葛平广苏黎明刘杰郑丽和苏良碧徐军王勇刚 Shandong Provincial Key laboratory of Optics and Photonic Devices College of Physics and ElectronicsShandong Normal University Key laboratory of Transparent and Opto-functional Inorganic Materials Shanghai Institute of CeramicsChinese Academy of Sciences State Key laboratory of Transient Optics and Photonics Xi’an Institute of Optics and Precision MechanicsChinese Academy of Sciences

By using a reflective graphene oxide as saturable absorber, a diode-pumped passively mode-locked Yb^3＋：Sc2Si O5（Yb：SSO） laser has been demonstrated for the first time. Without extra negative dispersion compensation, the minimum pulse duration of 1.7 ps with a repetition rate of 94 MHz was obtained at the central wavelength of 1062.6 nm. The average output power amounts to 355 m W under the absorbed pump power of 15 W. The maximum peak power of the mode-locking laser is up to 2.2 k W, and the single pulse energy is 3.8nJ.

关键词： reflective graphene oxide absorber Yb^3+:Sc2SiO5 crystal passive mode-locking diode pump