开展托卡马克等离子体中杂质输运与杂质控制研究对于提升等离子体约束性能与保障装置安全有重要意义。为了在EAST（Experimental Advanced Superconducting Tokamak）托卡马克装置上开展杂质输运研究，需要发展一套用于注入示踪杂质粒子的激光吹气（Laser Blow-off，LBO）微量杂质注入系统。本文描述了一种用于EAST托卡马克装置上LBO系统的控制系统设计过程与测试结果。该系统采用了全新的自动控制流程，使得系统可以重复、定量地向EAST等离子体注入不同元素的示踪杂质粒子。该设计通过STM32单片机系统实现对聚焦透镜位移、激光器被触发时刻的准确控制，且激光光斑直径可调，以改变杂质注入量。测试结果显示，系统能快速检测到外触发信号并实现精确定时，激光光斑聚焦位置误差小于0.40 mm，达到激光吹气杂质注入实验要求。本研究对在EAST装置上开展等离子体杂质输运研究具有重要意义。

Output power and reliability are the most important characteristic parameters of semiconductor lasers. However, catastrophic optical damage (COD), which usually occurs on the cavity surface, will seriously damage the further improvement of the output power and affect the reliability. To improve the anti-optical disaster ability of the cavity surface, a non-absorption window (NAW) is adopted for the 915 nm InGaAsP/GaAsP single-quantum well semiconductor laser using quantum well mixing (QWI) induced by impurity-free vacancy. Both the principle and the process of point defect diffusion are described in detail in this paper. We also studied the effects of annealing temperature, annealing time, and the thickness of SiO₂ film on the quantum well mixing in a semiconductor laser with a primary epitaxial structure, which is distinct from the previous structures. We found that when compared with the complete epitaxial structure, the blue shift of the semiconductor laser with the primary epitaxial structure is larger under the same conditions. To obtain the appropriate blue shift window, the primary epitaxial structure can use a lower annealing temperature and shorter annealing time. In addition, the process is less expensive. We also provide references for upcoming device fabrication.

The laser-induced damage threshold (LIDT) of plate laser beam splitter (PLBS) coatings is closely related to the subsurface absorption defects of the substrate. Herein, a two-step deposition temperature method is proposed to understand the effect of substrate subsurface impurity defects on the LIDT of PLBS coatings. Firstly, BK7 substrates are heat-treated at three different temperatures. The surface morphology and subsurface impurity defect distribution of the substrate before and after the heat treatment are compared. Then, a PLBS coating consisting of alternating HfO₂–Al₂O₃ mixture and SiO₂ layers is designed to achieve a beam-splitting ratio (transmittance to reflectance, s-polarized light) of approximately 50:50 at 1053 nm and an angle of incidence of 45°, and it is prepared under four different deposition processes. The experimental and simulation results show that the subsurface impurity defects of the substrate migrate to the surface and accumulate on the surface during the heat treatment, and become absorption defect sources or nodule defect seeds in the coating, reducing the LIDT of the coating. The higher the heat treatment temperature, the more evident the migration and accumulation of impurity defects. A lower deposition temperature (at which the coating can be fully oxidized) helps to improve the LIDT of the PLBS coating. When the deposition temperature is 140°C, the LIDT (s-polarized light, wavelength: 1064 nm, pulse width: 9 ns, incident angle: 45°) of the PLBS coating is 26.2 J/cm², which is approximately 6.7 times that of the PLBS coating deposited at 200°C. We believe that the investigation into the laser damage mechanism of PLBS coatings will help to improve the LIDT of coatings with partial or high transmittance at laser wavelengths.

改进了描述光学材料强激光损伤的吸收波前模型，在原有模型的基础上引入了杂质缺陷吸收项，并将一维形式推广到了三维。利用改进后的吸收波前模型，数值模拟了红外单晶硅光学材料在波长1064 nm皮秒激光辐照时杂质源（以金属铁为例）附近材料的温度、损伤半径及损伤阈值等变化情况，并分析了光学材料初始温度对损伤阈值的影响规律。数值结果显示：（1）与传统的热传递模型不同，在损伤阈值附近，激光场能量密度从低于损伤到达到（或超出）损伤的微小变化导致温度场的巨大变化；（2）达到损伤能量密度后，杂质附近的最高温度及利用吸收波前表征的材料损伤半径随着辐照能量密度的增加近似线性增长；（3）激光损伤阈值随着材料初始温度的增加而降低。研究结果表明改进后的吸收波前模型可以较好地描述光学材料的杂质缺陷诱导强激光损伤：相比于传统的热超导模型，吸收波前模型可以更合理的表示损伤阈值附近温度场的突变，并可定量分析杂质诱导光学材料的强激光损伤尺寸。另外对单晶硅吸收波前模型的研究还显示提升材料的初始温度可以有效降低材料的强激光损伤阈值，这为提升光电对抗中光电探测器的激光损伤效率提供了一种思路。