Fig. 1. Energy level structure and spectrum of Yb∶YAG

Fig. 2. Self developed multiple-pass pumping system and the crystal

Fig. 3. Schematic of the pump module and the pump light spot on the crystal

Fig. 4. Absorption efficiency of thin-disk crystal versus number of pump passes

Fig. 5. Schematic of the Yb∶YAG thin disk laser based on the 48-passes pumping system

Fig. 6. Output characteristics of the pump source

Fig. 7. Output performance of the Yb∶YAG thin-disk laser