208 W single-frequency 1064 nm laser based on a single-crystal fiber master-oscillator power amplifier

High-power all-solid-state continuous-wave (CW) single-frequency laser with high linear polarization is a significant source for quantum optics and precision measurement. In this Letter, a high-power linearly polarized CW single-frequency laser based on the single-crystal fiber (SCF) master-oscillator power amplifier (MOPA) is presented, in which a homemade 140 W low-noise CW single-frequency laser and a Nd:YAG SCF are firstly employed as the seed laser and the medium of the MOPA, respectively. The mode-matching between the pump laser propagated with waveguide form and the freely propagated seed laser is optimized by considering the influence of the degradations of the polarization and the beam quality. Finally, when the incident powers of the pump and seed lasers are 262.6 W and 126.3 W, respectively, the seed waist radius is optimized to 200 μm. In this case, the output power of the linearly polarized laser reaches up to 208 W, which is the highest output power, to the best of our knowledge. The presented results provide a good reference for implementing a high power and high degree of the polarization and good beam quality laser based on the SCF MOPA.