a tunable continuous wave single-longitudinal-mode fiber laser is proposed and developed. a saturable absorber, as well as, an all-fiber fabry-perot filter was used in the laser cavity to reduce mode-hopping. the laser was tunable from 1 565nm to 1 575nm and could produce an output power of 300m w while still maintaining single-mode operation with no mode-hoping. the linewidth of the laser was 􀁜9 mhz. the stability of the laser based on the length of the saturable absorber and the modal structure has been explored. we developed two brillouin fiber lasers using this laser as a pump source. a highly nonlinear photonic crystal fiber and a chalcogenide fiber were used as the nonlinear medium. the brillouin fiber laser based on pcf could produce either single wavelength or multiwavelength laser outputs. further, we investigated the coupling mechanism for the pump light into the chalcogenide glass fiber. in all cases the lasers were operated at room temperature.