Spatial Hole Burning in Distributed-Feedback Fiber Laser and its Reduction by Grating Apodization

We monitor the up-converted fluorescence from the pumped distributed-feedback (DFB) fiber laser in Erbium-doped fiber to find the intra-cavity power distribution. The intense spatial hole burning (SHB) effect in uniform DFB fiber laser is investigated theoretically and experimentally. For the laser performance optimization, we employ the phase-shifted grating apodization to suppress the SHB effect. Through the proposed apodization structure, the effective reduction in SHB of the DFB fiber laser is achieved.