Abstract
Thin disk geometry for laser active medium has advantages for high-average-power operation with good beam quality. However it is difficult to obtain high pumping efficiency due to the small thickness of the crystal. To improve the pumping efficiency, we have developed a side-pumped Yb: YAG/YAG composite disk laser with a stacked-LD tight-focusing technique. The maximum output power was 235-W from one disk with the optical efficiency of 0.38.
