Three-wavelength thulium-doped fiber random laser based on grating feedback technology

A linear cavity three-wavelength thulium-doped fiber random laser is demonstrated by using a femtosecond laser introduced random fiber grating to provide random distributed feedback and a superimposed-fiber Bragg grating to select lasing wavelengths. Stable three-wavelength random laser output is obtained at 1943.62, 1945.04 and 1946.32 nm. The 3-dB linewidth is less than 0.1 nm and the optical signal-to-noise ratio (OSNR) is up to 45.6 dB.