1720-nm narrow-linewidth all-fiber ring laser based on thulium-doped fiber

Abstract

A 1720-nm thulium-doped all-fiber laser based on a ring-cavity configuration is demonstrated. The long-wavelength lasing near the 1.9-mu m thulium emission peak was suppressed using a wavelength division multiplexer and single-mode-multimode-single-mode (SMS) fiber device, which together served as a short-pass filter instead of the grating devices usually used in 1.7-mu m thulium fiber lasers. A stable hundred-milliwatt-level 1720-nm laser output with a narrow spectral linewidth on the order of gigahertz was obtained after optimizing the output coupling, the active fiber length and the SMS device.