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31.
The lateral shift of focus diffracted and reflected beam and resolving power, insertion loss of a five channel grating spectrometer for 25 to 100 GHz are experimentally investigated. And some analysis for these results are also given. 相似文献
32.
以行波半导体光放大器速度方程为基础,采用传输矩阵方法,对锥形结构半导体光放大器的增益和饱和特性进行理论研究。讨论了不同锥形长度,不同结构时的增益和饱和特性差异。理论研究表明,锥形结构能改善半导体光放大器的偏振灵敏度。在同一锥度下,长锥形长度能提高饱和增益,降低偏振度。在进行半导体光放大器有源条结构设计时要综合考虑锥度及锥形长度的影响,以实现结构优化 。 相似文献
33.
Xiangdong Liu Hongwei Liu Kexu Yuan Huiping Du 《International Journal of Infrared and Millimeter Waves》1991,12(9):1023-1034
According to the angular-spectrum method, a radiation beam of an antenna horn in the Fresnal region is decomposed into the plane waves with the fast Fourier transform algorithm and the waves diffracted from a reflection grating are superposed as a diffracted beam. Compared with the reflected beam from the same size mirror, the radiation half width of the diffracted beam from a grating is narrower and its lateral shape is shift. These performances have been experimentally verified at Ka-band by: (1). The relative diffraction efficiencies in the first order with two triangular gratings which is put along propagating direction of a beam produced by a conical lens-horn. (2). H-plane lateral width with power—3dB lapsed of the focus beam from a grating and a mirror in a grating spectrometer for millimeter waves (25–100 GHz). 相似文献
34.
35.
Novel oxyfluoride glasses are developed with the composition of 30SiO2-15Al2O3-28PbF2-22CdF2-0.1TmF3 - xYbF3 - (4.9 - x) AlF3(x=0, 0.5, 1.0, 1.5, 2.0) in tool fraction, Furthermore, the upconversion luminescence characteristics under a 970nm excitation are investigated. Intense blue, red and near infrared luminescences peaked at 453nm, 476nm, 647nm and 789nm, which correspond to the transitions of Tm^3+: ^1D2 →^3F4, ^1G4 →^3H6, ^1G4 →^3F4, and ^3H4 →^3H6, respectively, are observed. Due to the sensitization of Yb^3+ ions, all the upconversion luminescence intensities are enhanced considerably with Yb^3+ concentration increasing. The upconversion mechanisms are discussed based on the energy matching rule and quadratic dependence on excitation power. The results indicate that the dominant mechanism is the excited state absorption for those upconversion emissions. 相似文献
36.
等离子体氧化nc-Si/SiO_2多层膜的蓝光发射 总被引:1,自引:0,他引:1
报道了在等离子体增强化学气相沉积 (PECVD)系统中用交替淀积 a-Si对其进行原位等离子体氧化的方法制备了 a-Si∶H/ Si O2 多层膜。随着 a-Si∶H子层的厚度从 3 .8nm减小到 1 .5 nm,a-Si∶H/ Si O2 多层膜的光吸收边和光致发光 (PL )出现了蓝移。在晶化的 a-Si∶ H/ Si O2 多层膜中不仅观察到室温下的红光带 (80 0nm)的发光峰 ,而且还观察到蓝光发射 (4 2 5 nm) ,结合 Raman,TEM和 PL测试 ,对其原因作了简单的分析 相似文献
37.
Hongwei Yu 《General Relativity and Gravitation》1991,23(3):297-304
By solving the coupled SU(5) Einstein-Yang-Mills-Higgs equations, we obtain the exact Reissner-Nordstrom type gravitational field of a family of spherically symmetric SU(5) dyons with magnetic charge 1/2e. 相似文献
38.
39.
Xie Ruixiang Wang Min Duan Changchun Yan Yihua R. A. Sych A. T. Altyntsev 《中国科学A辑(英文版)》2002,45(1):97-105
A complex solar radio moving type IV burst was observed on 23 September 1998 with the broadband (1.0–2.0 GHz and 2.6–3.8 GHz) spectrometers with high temporal and spectral resolutions at National Astronomical Observatories of China (NAOC). Comparing to the high spatial resolution data of Siberian Solar Radio Telescope (SSRT), we find that this burst is a rare type of moving type IV burst which is caused by the expanding arches, and the spatial structure oscillations of the radio sources are related with the time structure pulsations of the radio emission. Furthermore, the burst is associated with the multiple quasi-periodic long-term pulsations, and this suggests the existence of multi-scale magnetic structures in a large expanding coronal arch. We think the moving type IV burst is due to the synchrotron emission of the energetic electrons trapped in the expanding arch, and the multiple quasi-periodic pulsations are due to the second harmonic plasma emission. 相似文献
40.
Wang Yongqian Liao Xianbo Diao Hongwei Cheng Wenchao Li Guohua Chen Changyong Zhang Shibin Xu Yanyue Chen Weide Kong Guanglin 《中国科学A辑(英文版)》2002,45(10):1320-1328
A set of a-SiOx:H (0.52 <x< 1.58) films are fabricated by plasma-enhanced-chemical-vapor-deposition (PECVD) method at the substrate temperature
of 250°C. The microstructure and local bonding configurations of the films are investigated in detail using micro-Raman scattering,
X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). It is found that the films are
structural inhomogeneous, with five phases of Si, Si2O:H, SiO:H, Si2O3:H and SiO2 that coexist. The phase of Si is composed of nonhydrogenated amorphous silicon (a-Si) clusters that are spatially isolated.
The average size of the clusters decreases with the increasing oxygen concentration x in the films. The results indicate that
the structure of the present films can be described by a multi-shell model, which suggests that a-Si cluster is surrounded
in turn by the subshells of Si2O:H, SiO:H, Si2O3:H, and SiO2. 相似文献