Linear cavity all-fiber dual-wavelength actively Q-switched fiber laser with a Sagnac interferometer

We report an all-fiber dual-wavelength actively Q-switched pulsed laser. The linear cavity is limited by two fiber Bragg gratings with central wavelengths of 1538.3 nm and 1548 nm respectively in one side and Sagnac interferometer (SI) in the other side. The pump power is coupled into the doped fiber through a beam combiner. The SI used to equalize generated laser lines competition by cavity losses adjustment is formed by high birefringence (Hi-Bi) fiber in the loop. The SI spectrum wavelength displacement adjustment is performed by temperature variations applied on the Hi-Bi fiber loop with a temperature controller. The Q-switch operation is achieved at pulse repetition rate of 120 kHz with average pulsed output power of 404 mW and pulse duration of 470 ns.