向内发射磁绝缘振荡器

提出了一种向内发射磁绝缘振荡器,并给出了微波轴向提取的方法。这种新型结构通过外置阴极、内置阳极,使参与束波作用的轮辐电流通过阳极回流提供了自磁绝缘的角向磁场,有提高器件效率的可能。而外置阴极使阴极的发射面积增大,发射电流密度减小,有利于延长阴极寿命。通过粒子模拟,得到了几何参数与磁绝缘线振荡器输出功率的关系。在电压890 kV,电流56.1 kA下,输出功率为3.6 GW,频率为8.2GHz。     

Widely ultra-narrow linewidth 104 nm tunable all-fiber compact erbium-doped ring laser

A widely tunable narrow linewidth compact erbium-doped all-fiber ring laser with 104 nm tuning range was reported. An all-fiber Fabry-Perot filter (FFP-TF) was used to realize the laser tuning output, and the wavelength at constant voltage had high time stability. With the 8 m length erbium-doped fiber as gain medium, we realized widely tunable laser from 1513 to 1617 nm with the linewidth less than 40 pm at any wavelength. Pumped by the 976 nm laser diode, the fiber laser worked with slope efficiency of above 10% and threshold of less than 21 mW.     

Growth and spectral properties of Yb:Ca0.28Ba0.72Nb2O6 disordered crystal

The growth, XRD patterns, spectral properties, and fluorescence decays of Yb:Ca_0.28Ba_0.72Nb₂O₆ (Yb:CBN) with doping concentration of 1 at.% and 5 at.% were studied. The peak absorption cross-section and the emission cross-section were calculated. Larger Stark splitting of Yb:CBN offers the prospect of the quasi-four level laser operation.     

High-efficiency resonantly pumped room temperature Ho:YVO4 laser

An efficient 2 μm room temperature Ho:YVO(4) laser resonantly pumped by a 1.94 μm Tm:YAP laser is demonstrated, for the first time to our knowledge, in this Letter. Up to 8.58 W of laser output at 2053 nm is obtained with the optical-to-optical conversion efficiency as much as 41.2%. The output beam had quality of M² factor with Mx(2) of 3.58 and My(2) of 1.76 at 8 W output level. In addition, we also obtained 4.18 W laser output at 2066 nm and 7.04 W at 2040 nm from the Ho:YVO(4) laser with conversion efficiency of 27.8% and 33.8%, respectively.     

Room temperature operation of 2-μm microchip Tm,Ho:Lu2SiO5 laser

Room temperature operation of a c-cut microchip Tm,Ho:Lu₂SiO₅ laser end-pumping by a fibercoupled laser-diode is reported. A 4.03 W incident pump power is used to generate a maximum laser output of 98 mW, representing 2.43% optical-to-optical conversion efficiency and a 4.38% slope efficiency corresponding to incident power. In the experiment, the oscillating wavelengths shifting from 2.084 to 2.089 μm has been observed and approximately 10 mW single 2.087 μm wavelength oscillation has been obtained by changing the pump power to 1.43 W and the position of the pump focus.     

Absolute small-angle measurement based on optical feedback interferometry

We present a simple but effective method for small-angle measurement based on optical feedback interferometry （or laser self-mixing interferometry）. The absolute zero angle can be defined at the biggest fringe amplitude point, so this method can also achieve absolute angle measurement. In order to verify the method, we construct an angle measurement system. The Fourier-transform method is used to analysis the interference signal. Rotation angles are experimentally measured with a resolution of 10^-6 rad and a measurement range of approximately from -0.0007 to ＋0.0007 rad.     

基于红外波段光谱吸收的小型化湿度探测系统

 探测系统的光源选择为垂直腔面发射激光器,选定水汽在1.854 μm的吸收峰。系统自动在直接测量法与谐波测量法之间切换,能够适应高低湿度环境。在低湿度环境检测中,利用二次谐波与一次谐波的比值来定标湿度,有效去除了光源不稳定对测量带来的影响;过采样的A/D转换结合数字锁相放大（DLIA）技术,提高了检测精度。系统通过以太网接口,可以实现远程数据采集。     

Injection-seeded Tm:YAG laser at room temperature

The solid-state, tunable, narrowband, high pulse energy and high reliability lasers are attractive source for LIDAR system. In this paper, we demonstrated a diode pumped injection-seeded 2 μm Tm:YAG laser. By inserting two F-P etalons into the laser cavity, linear-polarized single-frequency seed-laser was achieved at a wavelength of 2013 nm, with a maximum output power of 60 mW. Long-term and short-term frequency stability for the seed-laser were 1.27 × 10^− 7 and 97 Hz/μs, respectively. High power Q-switched laser was operated using a bowtie cavity, the bidirectional output of which was favorable for the injection-seeded. After injecting the seed-laser to the power-laser, single-frequency, nearly transform-limited pulsed 2 μm laser was obtained. As much as 2.0 mJ output energy was achieved at an operating repetition rate of 15 Hz, with a pulse width of 356.2 ns.     

不协调目标信息系统知识约简的比较研究

研究不协调目标信息系统的各种知识约简之间的关系。证明分布约简既是β上分布约简，也是β下分布约简，并且在一定条件下,β上、下分布约简与不协调目标信息系统的分配约简和最大分布约简等价。