Abstract The uniformity of temperature distribution of an end-pumped laser can be improved simply and effectively by introducing the correct amount of spherical aberration into the pump system. An iterative model of optical-thermal coupling is proposed to calculate the temperature distribution of the end-pumped laser amplifier. The results showed that, the thermal effect of the laser gain medium in the coupling system composed of spherical lenses decreased significantly compared with the coupling system composed of aspherical lenses. This is proved by a neodymium-doped yttrium orthovanadate (Nd:YVO4) amplification experimental system, which was end-pumped by a fiber-coupled laser diode (LD) with the optimized wavelength of 878 nm. A comparative study of the two pump systems showed that the decrease in the gain medium thermal wavefront peak-to-valley (PV), the thermal lens effect, and an improvement in beam quality are still observed in the pump amplification experiment with spherical aberration. At last, the relationship between the spherical aberration and the output brightness of the amplifier was established, which provides guidance for further optimization of the spherical aberration of coupling pump systems and improving the beam quality.

中文翻译：

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球面透镜泵浦系统产生漏斗形光束的激光热效应分析

摘要 通过在泵浦系统中引入正确的球面像差量，可以简单有效地提高端面泵浦激光器温度分布的均匀性。提出了一种光热耦合迭代模型来计算端部泵浦激光放大器的温度分布。结果表明，与非球面透镜组成的耦合系统相比，球面透镜组成的耦合系统中激光增益介质的热效应显着降低。这是由掺钕原钒酸钇 (Nd:YVO4) 放大实验系统证明的，该系统由光纤耦合激光二极管 (LD) 端部泵浦，优化波长为 878 nm。两种泵浦系统的比较研究表明，在具有球面像差的泵浦放大实验中，仍然观察到增益介质热波前峰谷 (PV) 的降低、热透镜效应和光束质量的改善。最后建立了球差与放大器输出亮度之间的关系，为进一步优化耦合泵浦系统球差和提高光束质量提供指导。