A Single Mode Fibre Laser by Applying Self-Injection Locking with a DFB Structure

We report a novel single-frequency fibre ring laser using self-injection locking with a distributed-feedback (DFB) fibre laser at 1550nm. The operatingwavelength is controlled by a saturable absorber and a DFB fibre laser in the ring cavity, the saturable absorber acts as a narrow band-pass filter. In the primary experiment, the laser output exceeds 100mW with the linewidth less than 2kHz. The laser is stable, and no mode-hopping is observed within eight hours. Compared with other cavity designs using spatial hole-burning, our laser shows high controllability.