Dual-wavelength fiber laser based on fine adjustment of cavity loss by a fiber optical loop mirror

We study experimentally the behavior of a dual wavelength Erbium doped fiber laser based on superimposed fiber Bragg gratings (SI-FBGs) and a loop mirror. The linear cavity is formed by a Hi-Bi Fiber Optical Loop Mirror (HBFOLM) and a SI-FBG. Three pairs of SI-FBGs were used to tune the dual wavelength laser at different wavelength ranges. The SI-FBGs were placed on a mechanical mount that allow compression, both lines are shifted simultaneously. The separation of SI-FBGs is 5nm, and the set of three SI-FBGs permit to cover almost the entire spectrum of erbium from 1529nm to 1556nm approximately. The HBFOLM is used as a spectral tunable filter, which adjusts the losses by controlling the temperature in the Hi-Bi fiber, in order to stabilize the dual wavelength emission of the laser.