1908nm Single Frequency Fiber Laser Based on Dual-Ring Composite Cavity and Fabry-Perot Ring Filter

A thulium-doped single-frequency fiber laser based on dual-ring composite cavity and Fabry-Pérot (F -P) ring filter is proposed. Combining with the narrow-band filtering characteristics of the F - P filter, the composite sub-cavity filtering technique is utilized to expand the free spectral range and further achieve stable single-frequency output power. The output wavelength of 1907.95nm with an optical signal-to-noise ratio (OSNR) of 45.5 dB is obtained. The wavelength and power jitter over 60 minutes are less than 0.03nm and 0.85dB, respectively. Experimental results demonstrate that the Tm-doped laser can operate in a stable single-frequency output state. This provides an experimental basis for the development of high-power Tm-doped fiber lasers for subsequent use in Doppler wind lidar systems.