脉冲半导体激光器端面抽运Nd:YAG晶体瞬态热分析

为了研究脉冲半导体激光器端面抽运激光晶体产生的热效应,对激光晶体瞬态温度场以及热形变场进行解析分析与计算。考虑到脉冲LD出射光具有超高斯分布,且Nd:YAG晶体热传导各向同性的特点,利用热传导Poission方程得到了超高斯分布脉冲LD端面抽运Nd:YAG晶体瞬态温度场以及热形变场的一般解析表达式,定量分析了单脉冲抽运过程中超高斯抽运光光斑半径及超高斯阶次、脉冲宽度对Nd:YAG晶体瞬态温场的影响以及准热平衡状态温度场的时变特性。结果表明,当脉冲LD端面抽运光具有3阶超高斯分布、抽运功率为80W、脉冲频率为100Hz、脉宽为200 s、钕离子掺杂质量分数为0.01的Nd:YAG晶体瞬态温度场随抽运脉冲呈现出周期性分布,准热平衡状态的温度在25.5℃到29.2℃之间成锯齿形周期分布;晶体抽运面的热形变量在0.13m和0.19m之间也呈现出周期性变化。该研究对于脉冲LD端面抽运全固态激光器热不敏谐振腔设计具有理论指导意义。

Transient thermal analysis of Nd:YAG crystal end-pumped by pulsed diode laser

In order to study thermal effect of laser crystal end-pumped by pulsed laser diode, transient temperature field and thermal deformation field on the laser crystal were analytically investigated and calculated. Taking into account the outgoing light pulse LD with the super-Gaussian distribution and the Nd:YAG crystal isotropic heat conduction characteristics, the general analytical expressions of the transient temperature field and thermal deformation field of Nd:YAG crystal end-pumped by super-Gaussian distribution were obtained based on Poission equation of thermal conduction. The effect of the super-Gaussian pump light spot radius and super-Gaussian order times, pulse width on the transient temperature field of Nd:YAG crystal during the single-pulse-pumped and the quasi-thermal equilibrium temperature field of time-varying characteristics were quantitatively analyzed. The results show that when the LD end-pumped pulsed light has a third-order super-Gaussian distribution, the pump power is 80W, pulse frequency is 100Hz, pulse width is 200s, the mass fraction of neodymium-doped 0.01 Nd:YAG crystal transient temperature field with the pump pulse showing a periodic distribution, the quasi-thermal equilibrium the temperature of 25.5℃ to 29.2℃ into a zigzag shape between the distribution of the period. Crystal surface heat pump shape variables between 0.13m and 0.19m showing cyclical changes. The results have the theoretical instruction for designing the heat insensitive resonant cavity for the pulsed LD end-pumped all solid-state lasers.