Fig. 1. Experimental setup and spot size. (a) Schematic of experimental setup; (b) spot size distribution in resonant cavity

Fig. 2. Schematics of beam spatial walk-off principle.

Fig. 3. Output power of 355 nm UV laser versus pump power. (a) Under different walk-off conditions; (b) under different SHG crystal lengths

Fig. 4. Output power of 532 nm green laser versus pump power under different SHG crystal lengths

Fig. 5. Beam quality of 355 nm UV laser. (a) Under walk-off superposition condition; (b) under walk-off compensation condition

Fig. 6. Output power of 355 nm UV laser versus pump power under different repetition frequencies

Fig. 7. Waveform and power stability at maximum average power output. (a) 355 nm UV laser pulse waveform; (b) 355 nm UV laser power stability