Noise Properties in SESAM-Based Mode-Locked Laser With Intracavity Pump Reflection Coating

We investigate the intensity noise and microwave phase noise properties in an SESAM-based mode-locked fiber laser operating at 1.55 μm with intracavity pump reflection coating. Two lasers with similar design are made for comparison with one having a pump reflection coating whereas the other one has not. The noise conversion from pump relative intensity noise (RIN) to the RIN and phase noise of two lasers is evaluated experimentally. It is found that although the laser with pump reflection coating has much lower self-starting pump power and higher slope pumping efficiency, the pump-RIN-to-laser-RIN conversion scales as the square of the slope efficiency at low-frequency region and thus is increased by ~7 dB in the laser with coating. The pump-RIN-to-laser-phase-noise conversion is also increased due to the existence of the slow saturable absorber effect.