Fig. 1. Optical structure of 1064 nm linearly polarized single-frequency fiber amplifier

Fig. 2. End face of the 3C fiber

Fig. 3. Slop efficiency of the single-frequency fiber amplifier

Fig. 4. Laser spectrum at the maximum output power

Fig. 5. Spot morphology and beam quality

Fig. 6. Laser line-width at 138 W output power

Fig. 7. Polarization extinction ratio at different output power

Fig. 8. Laser pulse waveform and repetition of the pulsed laser