Minimizing Thermal Load and Stabilizing Mode in Yb:YAG Thin Disk Laser by 1030 nm Multi-Pass Pumping

We report for the first time a 1050 nm Yb:YAG thin disk laser multi-pass pumped by a 1030 nm laser with minimal thermal load and stable laser mode. The low quantum defect and anti-Stokes fluorescence cooling decrease the heat generation inside gain medium efficiently, leading to a maximum total fractional thermal load of 1.05% in consideration of the additional thermal load caused by roughness surface on the side of thin disk. And no significant temperature difference was observed in pumped area. In addition, the thin disk shaped structure with multi-pass pumping scheme can not only overcome the shortcoming of low absorption coefficient at 1030 nm but also stabilize the laser mode fundamentally, and the beam quality and efficiency are then promoted. Besides, this laser can scale the output power easily by increasing the number of pump passes and pumped spot size. As a result, a 60-pass pumping scheme delivered an average power of 6.32 W operated at fundamental mode, and the optical to optical efficiency and slope efficiency were 18.1% and 31.4%, respectively.