Zhu Guangzhi, Zhu Xiao, Dai Zhongxiong, Wang Zexiong, Zhu Changhong
Appl Opt. 2015 Apr 1;54(10):3024-31. doi: 10.1364/AO.54.003024.
An analytical model of the thermal effect and optical path difference (OPD) of a thin-disk laser is developed by an arbitrary form pumping spot. Based on the analytical model, the distribution of temperature, stress, and strain can be derived using a super-Gaussian form pumping spot. The total OPD caused by temperature gradient, axial thermal strain, thermal strain-induced birefringence, and deformation of the thin-disk crystal is discussed for different super-Gaussian factors and is separated into spherical and aspherical parts. The analytical results show that the aspherical part of the OPD is the main reason leading to the decrease of the laser beam quality and it is closely related to super-Gaussian factors, which are very useful for thin-disk laser design and evaluation.
通过任意形式的泵浦光斑建立了薄盘激光器热效应和光程差（OPD）的解析模型。基于该解析模型，利用超高斯形式的泵浦光斑可以推导温度、应力和应变的分布。针对不同的超高斯因子，讨论了由温度梯度、轴向热应变、热应变诱导双折射以及薄盘晶体变形引起的总光程差，并将其分为球面和非球面部分。分析结果表明，光程差的非球面部分是导致激光束质量下降的主要原因，且与超高斯因子密切相关，这对薄盘激光器的设计和评估非常有用。
