脉冲LD端面泵浦YAG/Nd∶YAG复合晶体热效应分析

Thermal Effect Analysis of Pulsed LD End-Pumped YAG/Nd∶YAG Composite Crystal

为了解决LD端面泵浦晶体引起的热效应问题,根据脉冲LD端面泵浦复合晶体工作特点,利用热传导理论建立了脉冲激光二极管泵浦YAG/Nd∶YAG复合晶体的有限元热模型。定量分析了泵浦功率、未掺杂晶体厚度、脉冲宽度对复合晶体温度场及热形变量的影响。结果表明,当掺杂晶体厚度为8 mm,未掺杂晶体厚度为3 mm,脉冲宽度为3 ms,经光学耦合系统准直聚焦的泵浦光斑半径为300μm,重复频率为100 Hz时,使用泵浦功率为80 W的脉冲LD端面泵浦复合晶体YAG/Nd∶YAG,泵浦端面中心的最高温度及最大热形变量分别66.84℃和0.12μm。可见,复合晶体能有效缓解晶体的温升和晶体端面的热形变。该研究为实现Nd∶YAG激光器高功率输出目标提供了理论指导。

Based on the working characteristics of the pulsed laser diode(LD)endpumped composite crystal,a finite element thermal model of the pulsed LD pumped YAG/Nd∶YAG composite crystal was established using the heat conduction theory to solve the thermal effect caused by the LD endpumped crystal.The effects of pump power,undoped crystal thickness,and pulse width on the temperature field and thermal deformation of the composite crystal were quantitatively analyzed.The results show that when the thickness of the doped crystal is 8 mm,the thickness of the undoped crystal,pulse width,and repetition rate is 3 mm,3 ms,and 100 Hz,respectively.Furthermore,the radius of the pump spot collimated and focused by the optical coupling system is 300μm when a pulse with a pump power of 80 W is applied.In the LD endface pumped composite crystal YAG/Nd∶YAG,the highest temperature and maximum thermal deformation available at the center of the endface pumped are 66.84℃and 0.12μm,respectively.It is thought that the composite crystal can effectively reduce the hightemperature rise of the crystal and the thermal deformation of the endface of the crystal.This conclusion provides theoretical guidance for realizing the high power output of a Nd∶YAG laser.