Study on compensation of thermal lens in high power high repetition solid-state laser

A model which treated the active medium as a thick lens was established to analyze the effects of thermal lens in the resonator. By using the matrix method, the equivalent resonator performance was studied. The uniformity of pump energy distribution was improved. An unstable plane-convex resonant cavity with special parameters was designed based on the calculation result of thermal lens compensation. The optimum radius of the rear convex mirror was presented which could efficiently compensate the effect of thermal lens. A beam divergence less than 1.3 mrad was achieved.