端侧面组合抽运DPL热透镜效应研究

通过数值计算发现：在端侧面组合抽运DPL中，晶体横截面上的温度分布接近于轴对称分布，并且端面抽运功率占有率越大，温度分布越接近于轴对称分布。将端侧面组合抽运DPL中的热效用等效薄透镜近似，给出了等效热透镜焦距的计算方法，分析了组合抽运引起的热透镜效应对基横模振荡光的光斑尺寸和衍射损耗的影响。在总抽运功率一定的情况下，端面抽运功率占有率的变化对热透镜焦距有一定的影响，占有率越大，热透镜焦距越长。提高端面抽运功率占有率，可在一定程度上减小热透镜效应对振荡光束尺寸和衍射损耗的影响。

Thermal lens effect in end-and-side pumped DPL

The numerical computation for an end-and-side pumped DPL indicates the temperature distribution in the cross section of the crystal is nearly axis symmetric, and the more proportion the end-pumping power occupies, the more axis symmetric the temperature distribution is. The thermal effect in an end-and-side pumped DPL was approximated with an equivalent lens. The calculation method for the focal length of the thermal lens was introduced. The influence of the thermal lens effect caused by combination pump on the spot radius of the fundamental-transverse-mode oscillation beam and the diffraction loss was analyzed. The proportion variation of the end-pumping power has some influence on the focal length of the thermal lens under a given total pumping power. The influences of the thermal lens effect on the oscillation beam radius and diffraction loss can be reduced by increasing the proportion of the end-pumping power.