Self-injection linear polarization locking of a fiber laser

We present a novel approach for linear polarized operation of a fiber laser not requiring any intra-cavity components, but relying on an external self-seeding effect. A small fraction of back-reflected polarized light created in an external cavity consisting of fused coupler, polarizer and fiber Bragg grating is sufficient to seed and lock the laser to linear polarized operation. This approach enables the construction of polarized monolithic fiber lasers, minimizes intra-cavity losses and drastically reduces parasitic amplified spontaneous emission. We experimentally demonstrate strong polarization locking in an Yb-doped fiber laser with extinction ratio of 500:1 at 1154 nm.