Low-frequency noise suppression of a fiber laser based on a round-trip EDFA power stabilizer

We have designed a power stabilizer based on a round-trip erbium-doped fiber amplifier (EDFA) structure to suppress the low-frequency relative intensity noise (RIN) for a narrow linewidth fiber laser. The noise suppressor is analyzed theoretically and its feasibility is verified experimentally. For a short-cavity single-frequency fiber laser with this device, about 20 dB low-frequency RIN improvement is achieved (down to -120 dB Hz(-1) at 10 Hz). The corresponding frequency noise is also reduced by a factor of 1.6. The proposed method is an effective solution to achieve a low-frequency low RIN laser source for highly coherent detection applications.