二极管泵浦高能固体激光器中的光热耦合现象

Optic-thermal coupling in high-power diode pumped solid-state lasers

为满足二极管泵浦的高能固体激光器(DPSSL)的理论分析要求,研究了DPSSL中产生光热耦合现象的物理机制。在微观上,上激光能级粒子的热弛豫导致增益介质的产热与激光场强度分布相关,而激活离子在各Stark能级间的热配分使得激光场分布与温度场相关。加之通常的热光效应所导致的激光场对温度场的依赖性,激光场和温度场产生彼此耦合。在大口径的高能DPSSL中该耦合现象变得重要,并且在这类激光器中大幅度改善了无耦合情况下的热透镜效应对光束质量的影响。

The interaction between the temperature field and the laser field plays a crucial role in solid-state lasers. In this paper, the optic-thermal coupling in the diode pumped solid-state lasers（DPSSL） is investigated. From the point of view of microcosmic physics, the thermal transition of particles at upper laser level makes heat generation of the laser crystals depend on the shape of the laser beam, while the laser field is influenced by the temperature in terms of thermal partition of doped particles. These effects, together with the usual thermal-optic effect of a fluctuation of the refraction index induce by uneven temperature distribution, lead to a complicated coupling between the laser field and the temperature field. It is shown that the optic-thermal coupling plays an important role in high-power DPSSL with large size beam, it also improves the beam quality by means of partly compensating to the thermal lens.