Research on LD-pumped single-frequency laser based on twisted-mode-cavity and RVBG

Abstract Single-frequency lasers have the advantages of good spectral purity, high peak spectral density, long coherence distance and low phase noise. They are widely used in fields such as laser spectroscopy, laser lidar, sodium guide stars, coherent optical communication and high-resolution measurement. We designed an all-solid-state single-frequency laser based on twisted-mode-cavity (TMC) structure and used a reflective volume Bragg grating (RVBG) to replace the ordinary output mirror. Through the composite mode selection effect of the twisted-mode-cavity and RVBG, the occurrence of multi-longitudinal mode oscillation is eliminated successfully, and precise optical frequency selection is achieved. When the pump power reached 88.0 W, the output power was 1.6 W, allowing for stable single-frequency laser operation at 1064.44 nm, with an output laser linewidth of 9.77 × 10 −3 pm, the corresponding slope efficiency was 10.00%, and the light-to-light conversion efficiency was 1.82%. The power instability was less than 4.44% and the beam quality factor were M x 2 = 1.35 , M y 2 = 1.38 . Experimental results show that compared with using a RVBG or twisted-mode-cavity individually, the combination of the two methods can significantly compress the laser linewidth and achieve single-frequency laser output.