为了解决激光二极管(Laser Diode,LD)端面泵浦的热容激光器在泵浦阶段会在晶体内部产生大量废热的问题,由LD端面泵浦激光晶体的工作特点,建立了泵浦阶段无冷却、端面与空气热交换的Yb∶YAG复合晶体热模型.基于热传导理论,使用有限元方法对Yb∶YAG复合晶体的温度场、应力场及热形变场进行了计算,定量分析了键合长度与键合方式对温度场及热形变场的影响.研究结果表明:若以泵浦功率为50 W、泵浦光高斯半径为300 µm的激光二极管对晶体尺寸为3 mm ×3 mm ×4 mm、键合长度为1 mm、键合方式为单端键合,且掺杂浓度为5.0 at.％的Yb∶YAG复合晶体端面进行泵浦,且工作时长为2 s,晶体内部场的最高温升为248℃、最大热形变量为5.9515 μm、最大应力为3.70395 × 109 N/m2.研究结果对激光二极管端面泵浦的Yb∶YAG热容激光器的设计提供了理论依据.
Thermal effects of laser diode end pumped Yb∶YAG composite crystal heat capacity laser
In order to solve the problem that the heat capacity laser pumped by laser diode generate a large amount of waste heat inside the crystal during the pumping stage,a thermal model of Yb∶YAG composite crystal without cooling in the pumping stage and heat exchange between the face and air is established by the working characteristics of the LD end-pumped laser crystal.Based on the heat conduction theory,the temperature field,stress field and thermal de-formation field of Yb∶YAG composite crystal are calculated by finite element method.The effects of bonding length and bonding mode on the temperature field and thermal deformation field are quantitatively analyzed.The results show that if a laser diode with a pumping power of 50 W and a pumping optical Gaussian radius of 300 μm is used to pump the end face of Yb∶YAG composite crystal with a crystal size of 3 mm ×3 mm ×4 mm,a bonding length of 1 mm,a bonding mode of single end bonding,and a doping concentration of 5.0 at.％,and the working time is 2 s,The maxi-mum temperature rise of the internal field is 248 ℃,the maximum thermal shape variable is 5.9515 pm,and the max-imum stress is 3.70395 × 109 N/m2.The research results provide a theoretical basis for the design of Yb∶YAG heat capacity laser pumped by laser diode end face.
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