Fig. 1. Effect of focusing mirror position on parametric light spot

Fig. 2. Schematic diagram of output wavelength and gain intensity of fiber laser

Fig. 3. Structure diagram of fiber laser

Fig. 4. Schematic diagram of 1 064 nm fiber pumped MgO:PPLN-OPO experimental device

Fig. 5. Spectra of 1064 nm YDFL with different linewidths

Fig. 6. 1 064 nm YDFL power comparison before and after linewidth narrowing

Fig. 7. Output spectrum

Fig. 8. The corresponding output condition when the position of the pump uniform lens changes

Fig. 9. Output comparison before and after different pump duty cyclies

Fig. 10. 3.8 μm beam quality factor