给出了一种适用于空间应用的全固态高重复频率窄脉冲激光器。激光器采用超稳双porro棱镜直线谐振腔, 以LD侧面抽运Nd∶YAG板条, 磷酸氧钛铷(RTP)晶体作为电光调Q开关, 并利用偏振耦合输出激光。实现了激光脉冲重复频率为1 kHz、平均功率为1.15 W、脉冲宽度为1.3 ns、光束质量因子M2为M2x=1.20和M2y=1.23、波长为1064 nm的脉冲激光输出。激光器结构紧凑, 性能良好, 可作为未来新型空间探测激光雷达系统的光源。

报道了一种基于被动调Q Nd∶YAG 微片结构的主振荡功率放大和Nd∶YVO4板条多程放大的激光器。主振荡级采用Nd∶YAG/Cr4+∶YAG 被动调Q 微片激光器，在重复频率为1 kHz时，输出单脉冲能量为82 μJ 、脉冲宽度为1 ns的近衍射极限的激光输出。为了实现信号光在Nd∶YVO4中获得5 次放大，设计采用了多程往返光路。得到最大单脉冲能量为2.3 mJ ，脉宽为1 ns 的激光输出，峰值功率大于2 MW ，光束质量M2 因子为M 2x = 2.48 和M 2y = 1.24 。该激光器结构简单、紧凑，采用传导冷却进行散热，适用于空间激光，在15 ℃~32 ℃的范围内，输出能量波动小于4%。

A compact passively Q-switched Yb:YAG microchip laser is demonstrated. Featuring a semiconductor saturable-absorber mirror (SESAM), the laser yields pulses of 219 ps when the length of the microchip Yb:YAG crystal is 100 μm and the beam quality is M2<1.3. To the best of our knowledge, pulses from the proposed laser are the shortest Q-switching pulses obtained from Yb:YAG microchip lasers currently available.

Gain medium of modern high-average-power solid-state lasers can produce distortion for the reason of thermal effect, such as YAG. Wavefront distortion and depolarization often occur simutaneously. The thermal stress of the high-power solid state laser slab is becoming a serious problem for hindering the further power increasing of the laser. A method for calculating the thermally induced refraction index in a pumped heat capacity slab laser was studied. In this method, the fourth-rank piezo-optics tensors of YAG crystal were transformed from the crystal lattice coordinate system to the laboratory coordinate system. With these new tensors, the thermally induced stress birefringence in a solid-state laser can be analyzed easily for any stress distribution. Furthermore, the calculations show that the birefringence in a zigzag slab depends on the angle under which the slab is cut from the boule. A theoretical description of the thermal and stress characteristics of heat capacity slab laser in two dimensional was also presented.

We investigate intersubband Rabi flopping in modulation-doped semiconductor quantum wells with and without the propagation effects, respectively. It is shown that propagation effects have a larger impact on Rabi flopping than the nonlinearities rooted from electron-electron interactions in multiple quantum wells. By using ultrashort \pi pulses, an almost complete population inversion exists if the propagation effects are not considered; while no complete population inversion occurs in the presence of propagation effects. Furthermore, the magnitude of the impact of propagation effects may be controlled by varying the carrier density.

高平均功率固体激光器的增益介质由于受热而容易发生畸变,如常用材料YAG,波前畸变和去偏振现象会同时发生,高热负载固体激光介质的热效应已成为制约激光器输出功率进一步提高的严重障碍。给出一种计算热容型板条激光器热感生折射率的方法。把YAG晶体的四阶压光张量从晶胞坐标系转换到实验室坐标系,采用经过坐标转换后的新的张量,可以分析在YAG激光器中任意应力分布引起的热感应双折射。进一步的计算表明,在zigzag板条激光器中,应力双折射率与板条从晶体毛胚上切割成材的角度有关。同时也对热容板条激光器的热效应和应力特性进行了二维的理论性概述。

The solid state heat capacity laser (SSHCL), as one of the most important high-power solid-state lasers, has attracted extensive attention. Numerical simulation of temperature and stress distributions of laser crystal slab in the heat capacity operation mode is a major means to understand the specific property of the laser. Using the method of plane stress approximation, the two-dimensional (2D) mathematical formulas that describe the temperature and stress distributions of laser diode (LD) pumped heat capacity slab laser are derived. Then the absorbed pump power density, 2D distributions of temperature and index of refraction are also analyzed and discussed. According to the results, the 2D distributions of temperature and stress are more homogeneous than that of the one-dimensional distributions.

In this paper we propose a system with the piezoelectric actuator by the single neuron adaptive PID controller for the grating tiling. Then the design of the control system as well as the control method by considering the nonlinearity of piezoelectric actuators is discussed. At last, close loop position examinations by the capacitive displacement sensor with nanometer scale precision are performed. The experimental results indicate that the system is working effectively. The system is provided with the characters of self-learning, easy calculating and adaptability as well as of a simple structure.

Based on the laser rate equations in a typical four-level system, we research the temperature-dependent gain characteristics of a solid-state heat-capacity laser (SSHCL) involving the small-signal gain coefficient and the gain distribution's uniformity. The influences of doping concentration of active ions and initial operating temperature on the small-signal gain coefficient are discussed for Nd-doped glass heat-capacity laser. Furthermore, the gain distributions of a slab laser gain medium operating in SSHCL mode are discussed.

In the 9th laser system of Shenguang II inertial confinement fusion (ICF) facility, tunable Fabry-Perot (F-P) filter is applied to compensate the FM-AM effect. According to the technical requirements of compensation device, a precise displacement monitor system using the capacitive displacement sensor with nanometer scale precision to stabilize the spacing of the tunable F-P filter is proposed firstly, then the basic structure and operating principle of the monitor system are analyzed. The scheme design of the driving circuit of capacitive displacement sensor, the data processing as well as the system controlling program are discussed in detail, and the precision of capacitive displacement sensor is calibrated. The experimental results show that the spacing stability of the tunable F-P filter is better than 15 nm/h and the modulation depth of the FM-AM effect is better than 4% by introducing the displacement monitor system.