Fig. 1. Schematic diagram of the frequency doubled CW single-frequency YDF MOPA.

Fig. 2. 1064 nm output power and backward light power of the main amplifier as a function of the pump power.

Fig. 3. Output spectra of the 1064 nm fundamental laser at different output powers: (a) wide spectra, (b) fine spectra.

Fig. 4. Spectra of the backward light from the 1064 nm main amplifier at different output powers: (a) wide spectra, (b) fine spectra.

Fig. 5. Dependence of the second-harmonic output power and the conversion efficiency on the pump power. A numerical fitting is also given.

Fig. 6. Linewidth measured with an FPI: (a) 1064 nm laser, (b) 532 nm laser.

Fig. 7. Far-field beam profile of the 532 nm laser.