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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 gain medium of high average power solid state laser is prone to distortion due to the heat. Such as common materials YAG, wavefront distortion and depolarization phenomena occur simultaneously. The thermal effect of the high thermal load solid laser medium has become a serious obstacle to the further improvement of the laser output power. A method of calculating the thermal induced refractive index of a heat capacity slab laser is given. The fourth-order calendering tensor of YAG crystal is converted from the cell coordinate system to the laboratory coordinate system. The thermal-induced birefringence caused by arbitrary stress distribution in YAG laser can be analyzed by using the new tensor after coordinate transformation. Further calculations show that in zigzag slab lasers, the stress birefringence is related to the angle at which slats cut into material from the crystal blank. At the same time, a two-dimensional theoretical overview of the thermal effects and stress characteristics of the heat-lasted strip lasers is also given.