1 四川大学电子信息学院, 四川成都 610064
2 中国空间技术研究院西安分院空间微波技术重点实验室, 陕西西安 710000
针对无源互调(PIM)严重影响卫星通信系统性能和稳定性问题, 提出了一种利用内导体非接触式结构实现低 PIM的同轴接头设计方法。设计并实现了 2款分别工作在 S波段和 C波段的内导体非接触式同轴接头: S波段的内导体非接触式同轴接头在 2.1~2.7 GHz下实测|S11 |<-30 dB, 通带内插入损耗小于 0.3 dB; C波段的内导体非接触式同轴接头在 3.5~4.2 GHz下实测|S11 |<-30 dB, 通带内插入损耗小于 0.2 dB。该改进型同轴接头设计方法为卫星通信系统的微波连接器的设计提供了重要的参考价值和新的研究思路。
内导体非接触式同轴接头 卫星通信系统 S波段 C波段 等效电路 coaxial connector of noncontact inner conductors satellite communication S band C band equivalent circuit 太赫兹科学与电子信息学报
2023, 21(7): 845
辐射研究与辐射工艺学报
2023, 41(1): 010101
1 新疆大学机械工程学院, 新疆 乌鲁木齐 830047
2 中国工程物理研究院材料研究所, 四川 绵阳 621907
3 四川大学物理学院, 四川 成都 610064
采用激光熔化沉积法制备AlCoCrFeNi2.5高熵合金,通过X射线衍射仪、扫描电子显微镜、能谱仪、电子背散射衍射技术和力学拉伸测试研究合金的凝固组织、元素分布和力学性能。研究结果表明,通过激光熔化沉积法制备的AlCoCrFeNi2.5高熵合金的微观组织为外延生长的柱状枝晶,其由一次和二次枝晶干处的面心立方(FCC)相与枝晶间隙处的体心立方(BCC)相组成。拉伸结果表明,在激光沉积方向,合金的抗拉强度达到1428 MPa,延伸率为25.8%。断口形貌显示出在 FCC 相区域观察到了大量的滑移轨迹,而位于枝晶间隙处的硬质BCC相能够有效阻碍滑移的扩展,使得FCC相中的位错密度进一步提高。拉伸变形过程中,合金内部组织中的FCC相与BCC相的耦合协同作用,可以促使AlCoCrFeNi2.5高熵合金表现出优异的综合力学性能。
材料 激光熔化沉积 高熵合金 微观组织 拉伸性能
沈阳化工大学信息工程学院, 辽宁 沈阳 110142
针对图像边缘与轮廓不能精确重构的问题,提出了一种基于灰度共生矩阵的多尺度分块压缩感知算法。该算法利用三级离散小波变换将图像分解为高频部分和低频部分。通过灰度共生矩阵的熵分析高频部分图像块的纹理复杂度,并根据图像块纹理进行再分块、自适应分配采样率。采用平滑投影Landweber算法重构图像,消除分块引起的块效应。对多种图像进行压缩重构仿真,实验结果表明,无观测噪声情况、采样率为0.1时,本算法在Mandrill图像上得到的峰值信噪比(PSNR)为25.37 dB,比现有非均匀分块算法提高了2.51 dB。不同噪声水平下,本算法的PSNR比无噪时仅下降了0.41~2.05 dB。对于纹理复杂度较高的图像,本算法的重构效果明显优于非均匀分块算法,对噪声具有较好的鲁棒性。
图像处理 压缩感知 灰度共生矩阵 自适应采样率 纹理复杂度 激光与光电子学进展
2021, 58(4): 0410002
Author Affiliations
Abstract
1 Department of Physics, College of Mathematics and Physics, Beijing University of Chemical Technology, Beijing 100029, China
2 Research Center for Optoelectronic Materials and Devices, School of Physical Science Technology, Guangxi University, Nanning 530004, China
3 Guangxi Key Laboratory of Processing for Non-Ferrous Metal and Featured Materials, Guangxi University, Nanning 530004, China
Aluminum nitride (AlN) is the promising substrates material for the epitaxial growth of III-nitrides devices, such as high-power, high-frequency electronic, deep ultraviolet optoelectronics and acoustic devices. However, it is rather difficult to obtain the high quality and crack-free thick AlN wafers because of the low surface migration of Al adatoms and the large thermal and lattice mismatches between the foreign substrates and AlN. In this work, the fabrication of AlN material by hydride vapor phase epitaxy (HVPE) was summarized and discussed. At last, the outlook of the production of AlN by HVPE was prospected.
Journal of Semiconductors
2019, 40(12): 121803
中国科学院上海光学精密机械研究所强场激光物理国家重点实验室, 上海 201800
基于蒙特卡罗光线追迹法，进一步研究了钕玻璃片状放大器三维空间聚光腔抽运分布的数值模拟。并且，结合氙灯的充放电回路及辐射光谱、放大自发辐射、以及激光脉冲受激辐射放大等相关数值计算模块，实现了片状钕玻璃放大器由储能至放大的整个过程的动态数值仿真。基于该数值模拟结果，设计研制的钕玻璃片状放大器已用于5 PW钛宝石啁啾脉冲放大器的抽运源中，其实验输出结果与数值计算结果基本一致。
激光器 片状放大器 光线追迹 钕玻璃 受激辐射放大 中国激光
2016, 43(12): 1201006
Author Affiliations
Abstract
1 Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
2 Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 2000500, China
We demonstrate a diode-pumped picosecond Yb-doped silicate Yb3+:Sc2SiO5 (Yb:SSO) chirped pulse amplifier. The seed source with a pulse width of 220 fs is a diode-pumped Yb:KGW femtosecond oscillator. A single chirped volume Bragg grating is employed both as a pulse stretcher and as a compressor to improve the compactness of the system. Stretched pulse is amplified using a diode-pumped Yb:SSO regenerative amplifier. The maximum amplified pulse energy obtained at a pump power of 13.5 W is 450 μJ. The amplified pulse is centered at 1033.3 nm before compression at a frequency of 1 kHz. After compression, the pulse energy is 315 μJ with a pulse duration of approximately 1 ps.
140.3280 Laser amplifiers 140.3615 Lasers, ytterbium 140.4050 Mode-locked lasers Chinese Optics Letters
2015, 13(1): 011403
Author Affiliations
Abstract
1 Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
2 Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 2000500, China
3 School of Physical Science and Technology, Shanghai Tech University, Shanghai 200031, China
We demonstrate the laser performances of Nd, Y:SrF2 crystals with Nd3+ concentrations of 0.15 and 0.43 at.%. The sample with 0.43 at.% Nd3+ concentration yields a maximum output power of 1.023 W at 1056.9 nm with a slope efficiency of 53%. The focal length of the thermal lens is analyzed for the 0.15 at.% Nd3+-doped crystal sample. An improved cavity is designed considering the thermal lens. The maximum output power is 464 mW at 1056.9 nm, with a slope efficiency of 36.1%. The wavelength is tuned within the range of 1049.74–1059.13 nm.
140.3580 Lasers, solid-state 140.3530 Lasers, neodymium 140.6810 Thermal effects Chinese Optics Letters
2014, 12(12): 121403
Author Affiliations
Abstract
A stable self-starting mode-locked Nd:YVO4 laser with a Herriott-type multiple-pass cavity (MPC) operating at 1 064 nm is demonstrated. An in-band 880-nm laser diode is used as an end-pump and a semiconductor saturable absorber mirror (SESAM) is used for passive mode locking (ML) and providing pulse durations of 14 ps. At a pump power of 26.4 W, the maximum average output power is as high as 10.5 W at a repetition rate of 22 MHz, which corresponds to a single pulse energy of 0.48 \mu J. Optical-tooptical conversion efficiency is as high as 39.8% at the maximum output power with a slope efficiency of 55.2%.
140.4050 Mode-locked lasers 140.3480 Lasers, diode-pumped 140.3580 Lasers, solid-state Chinese Optics Letters
2013, 11(8): 081401
Author Affiliations
Abstract
A wavelength-tunable, efficient, and high-average power single diode-pumped continuons wave (CW) Yb:SSO laser is reported. A maximum output power of 8.8 W at 1 062.6 nm is obtained using the absorbed pump power of 11.7 W, which corresponds to a slope efficiency of 85.5% and an optical-to-optical conversion efficiency of 48.9%. The wavelength tuning of the Yb:SSO laser pumped by the 976-nm LD is also investigated. The results show the tuning range from 1 002.30 to 1 068.47 nm, which corresponds to a tunability range of 66.17 nm.
140.3580 Lasers, solid-state 140.3615 Lasers, ytterbium 140.6810 Thermal effects Chinese Optics Letters
2012, 10(11): 111404
