Triple-Wavelength Thulium-Doped Fiber Random Laser Based on Random Fiber Grating

We demonstrate a triple-wavelength thulium-doped fiber random laser using 10 cm long grating to provide distributed feedback and superimposed Bragg as the wavelength-selective mirror. The inscribed in single-mode fibers femtosecond provides strong that avoids use of distance leads relatively low threshold power. Triple-wavelength output at wavelengths 1943.6, 1945.0 1946.3 nm was achieved with power 2.01 W, slope efficiency 7.86% maximum 151.8 mW when it pumped 793 diode. 3 dB linewidth less than 0.1 optical signal-to-noise ratio up 45.6 dB. Good wavelength stability achieved, which attributed narrow band stable reflection grating. time-domain characteristics were also measured analyzed, some self-pulsing caused by relaxation oscillations observed.