Frequency noise of high-gain phosphate fiber single-frequency laser

Frequency noise in single-frequency high-gain phosphate fiber lasers is investigated theoretically and experimentally. An analytical expression relating the pump fluctuations to the laser frequency noise is established and verified by a homemade single-frequency phosphate fiber laser. The theoretical and experimental results indicate that the frequency noise of the output laser can be reduced by lowering the intensity noise of pump source. This will help improving the laser performance and progress the wide application of this type of fiber laser.