Research on self phase-locked two-channel narrow linewidth laser

We have designed and constructed a self phase-locked two-channel narrow linewidth solid-state laser based on reflective volume Bragg grating (RVBG) as the output mirror. The resonant cavity of the laser is designed as a U-shaped structure, and two independent laser diode (LD)-side-pumped modules achieve passive phase locking of the output laser through mutual injection of photon energy. Compression of the linewidth is achieved by the RVBG. When the LD pump power was 70 W, the output powers of the two-channel lasers were 1.59 W and 1.61 W, the measured central wavelengths of the spectra were 1064.23 nm and 1064.24 nm, and the linewidths were 0.10 nm and 0.11 nm, respectively. The slope efficiencies of the two lasers are 9.5 % and 9.56 %, respectively, and their powers stability were both better than 3 %. The beam quality factors were Mx2=1.29, My2=1.31 and Mx2=1.32, My2=1.36, respectively. The interference fringes formed by the coherent superposition of two laser beams in the far field were observed through CCD, which verified the phase-locked coherence characteristics of the two lasers. The output power of the coherent combination laser is 2.64 W, with a corresponding efficiency of coherent combination is 82.5 %. The experimental results show that the laser can directly obtain two-channel narrow-linewidth continuous wave lasers output with phase locking and consistent laser intensity. Our research provides a new idea for obtaining a new type of high-quality narrow-linewidth coherent laser source