A Novel Dual-Wavelength DFB Fiber Laser Based on Symmetrical FBG Structure

A novel grating structure is proposed and demonstrated to obtain stable dual-wavelength (DW) distributed-feedback (DFB) fiber lasers at room temperature. The proposed grating is based on a symmetrical structure, where one half is periodically sampled by "0"-to-"pi" period and the other half is done by "pi"-to-"0" period. This structure can create two separated resonance cavities and hence achieve the stable DW lasing operation. By fabricating the proposed grating on a piece of Er : Yb-codoped fiber, we experimentally obtain a stable DW-DFB fiber laser with wavelength spacing of ~440 pm at room temperature