数值模拟抽运分布对端泵激光器晶体热透镜球差的影响

为了研究端面抽运情况下,激光晶体在不同分布的抽运光抽运时热透镜球差的变化,通过对稳态热传导方程和Zernike多项式的求解,建立了热透镜球差与抽运光强度分布的模型,对模型进行了理论分析和仿真研究,并对仿真结果做了进一步理论和仿真分析.结果表明:在相同的抽运功率下,二阶超高斯分布抽运光抽运时球差最大,且随着抽运分布系数k的增大(除高斯分布外)球差逐渐减小;随着抽运功率的增加,抽运分布系数k对球差的影响逐渐加重,且不同分布系数k所产生的球差差距逐渐增大;并对二阶超高斯分布抽运光抽运得到最强激光功率的照射范围进行了理论分析和仿真分析,得知在相同抽运功率下,二阶超高斯分布抽运光得到最强激光功率的范围最宽为0.30—0.63倍高斯半径.

Numerical simulation of effect of pump distribution on spherical aberration of end-pumped laser

In order to study the spherical aberration of thermal lens when the laser crystal is pumped with the pump light distributed differently and the pump light under the end-pumping condition, in this paper we establish a single-ended pump and constant temperature thermal model to analyze the working characteristics of the Nd:YVO₄ crystal. The steady state heat conduction equation and Zernike polynomials are solved, and the relationship between thermal spherical aberration and distribution of pump laser is established. The model is used in simulation, and the simulation results are further analyzed theoretically, showing that under the same pump power, the spherical aberration is greatest when the pump beam is of 2-order super-Gaussian distribution. The spherical aberration decreases with the increase of pump distribution coefficient k (except the Gaussian distribution). With the increase of pump power, the influence of pump distribution coefficient k on spherical aberration is aggravated gradually, and the difference in spherical aberration caused by different values of distribution coefficient k increases gradually. The range of strongest laser power of the 2-order super-Gaussian distribution pump is analyzed and simulated. Under same pump power, the maximum range of the strongest laser power of 2-order super-Gaussian distribution pump is 0.3-0.63 times the Gauss radius. The research methods and conclusions obtained in this paper have universal applicability and can be used for quantitatively analyzing the temperature distributions, thermal deformations, optical path difference distributions, and spherical aberration distributions of other laser crystals. At the same time, this study also provides a theoretical reference for improving spherical aberration from the perspective of changing the distribution of pump light and the laser output characteristics.