极小孔半导体激光器近场区光场分布研究

利用时域有限差分法(FDTD)计算和分析了极小孔半导体激光器输出光端面附近的光场分布,指出小孔激光器近场区域光场分布的特点,讨论了小孔大小和金属厚度对光场分布和光源分辨率的影响,得到设计和制备极小孔半导体激光器的优化方法.     

线电荷串产生的史密斯-帕塞尔辐射

采用积分方法分析了线电荷串,沿周期性理想金属光栅表面平行移动时产生的史密斯帕塞尔辐射。分别对短周期光栅、低能量线电荷串与长周期光栅、高能量线电荷串的辐射情况进行了数值计算。相对单个线电荷而言,N个线电荷与反射光栅作用产生的辐射场密度,在频率是线电荷串调制频率的整数倍处出现最大,辐射谱宽变窄;随电荷能量增高,辐射能量向高频方向移动,并具有强烈的定向性;可以通过调节线电荷调制频率等参量实现辐射电磁波频率锁定。研究结果表明,对高能量与低能量的电荷参量,适当选择光栅尺寸与线电荷串间隔周期,都可使辐射波工作于太赫兹波段。     

Optimization of a Cryogenic System at Temperature 2 K for the PKU-FEL Facility

The conceptual design of a cryogenic system at temperature 2 K for the Peking University Free Electron Laser （PKU-FEL） facility is carried out. In order to minimize the scale of the cryogenic system and the running cost, the superconducting accelerator and the superconducting injector will mainly run at a long-pulsed mode. Optimization of the 2-K cryogenic system is carried out based on the heat load estimation and running parameters. Total cooling power of 52.5 W for the long-pulsed mode is necessary for the PKU cryogenic system. The PKU cryogenic system will be the first 2-K system for accelerators in China and will provide experience for similar facilities.     

Simulation of Patterns and Qualitative Analysis of Pattern Rotation in an End-Pumped Nd：YVO4 Laser

We simulate some laser output patterns observed in our previous experiment employing superposition of Laguerre- Gaussian modes. The rotating pattern is qualitatively analysed from the point of contemporary spatial burning hole effect of the lasing crystal.     

Nd掺杂的Bi4Ti3O12变温X射线衍射分析

利用变温X射线衍射技术，在预烧过程中分析了Nd掺杂Bi4Ti3O12后生成Bi3.15Nd0.85Ti3O12（BNT）相的形成过程以及微结构的变化．实验观察到以30℃／min的升温速率，BNT相在700℃时开始形成，其衍射峰强度随温度的继续升高而增强，衍射峰半高宽随烧结时间延长而减小．X射线衍射分析结果表明，在900℃恒温条件下，烧结约2h，可形成单一的BNT相．     

光纤环形外腔半导体激光器频偏特性研究

本文给出了在环形光纤外腔光反馈之下半导体激光器频偏特性的小信号分析理论.分析表明,尤其在千兆赫以下的调制频段中,耦合腔相移、内外腔光耦合强度及内外腔光场相位失谐对频偏功率比均有显著影响.可望用作强度调制直接检测高速率、长距离光纤通信系统中的光源.     

Design of Two-Dimensional Photonic Crystal Edge Emitting Laser for Photonic Integrated Circuits

An edge emitting laser based on two-dimensional photonic crystal slabs is proposed. The device consists of a square lattice microcavity, which is composed of two structures with the same period but different radius of air-holes, and a waveguide. In the cavity, laser resonance in the inner structure benefits from not only the anomalous dispersion characteristic of the first band-edge at the M point in the first Brillouin-zone but also zero photon states in the outer structure. A line defect waveguide is introduced in the outer structure for extracting photons from the inner cavity. Three-dimensional finite-difference time-domain simulations apparently show the in-plane laser output from the waveguide. The microcavity has an effective mode volume of about 3.2（λ/nslab）^3 for oscillation mode and the quality factor of the device including line defect waveguide is estimated to be as high as 1300.     

Phase-Locked Fibre Array for Coherent Combination and Atmosphere Aberration Compensation

We report a fibre amplifier array that not only achieves coherent beam combination by compensation of phase noises of fibre amplifier, but also accomplishes correction of atmosphere aberration. It is of master-oscillatormultiple-amplifier （MOPA） configuration, which can be phase-locked by the multidither principle or heterodyne detection principle. First laboratory experiments of atmosphere aberration compensation of a three-element fibre amplifier array are reported. The atmosphere aberration is created by a phase screen in the experiment. The phase changes of the beam, which are introduced by the fibre amplifier and the phase screen, are both detected by the heterodyne detection method. Phase modulators are controlled to compensate for the phase in the three paths. No matter whether there is a phase screen producing atmosphere aberration or not, the dim dynamic interference fringes in the far field turn to a clear and stable pattern, and the peak intensity is maximized. It is indicated that the fibre amplifier array is phase-locked, and coherent combination of the three beams is achieved. It can be used not only to obtain high power fibre laser array but also in laser space communication.     

双折射双频激光器偏振特性的分析

用激光原理和晶体光学原理分析了腔内加旋光晶体的激光器输出光的偏振特性，实验和分析表明，激光器输出两束不同频率的垂直线偏振光，激光器两端输出光的偏振面有一夹角ａ，且此夹角与晶轴和传光方向的夹角θ有关。理论计算结果在双折射双频激光器的实验结果符合很好。     

半导体激光泵浦的掺铒光纤放大器新进展

本文作者曾于1991年4月采用国产元器件建立了国内第一台半导体激光泵浦的掺铒光纤放大器,当时增益为5.6dB.经过进一步的技术改进措施,依然是采用全部国产元器件,其增益已高达17.4dB.于1992年10月30日在上海市科委主持下,通过了以学部委员张煦教授为主任的鉴定委员会鉴定,得到好评