Using a passive fiber ring cavity to generate shot-noise-limited laser light for low-power quantum optics applications

High-stability single-frequency fiber lasers typically exhibit relative intensity noise that is far in excess of shot noise across a broad frequency range extending from dc to many tens of megahertz. This excess noise precludes the use of these fiber lasers in a range of precision interferometry and quantum optics applications. We present experimental results using a passive, high Q, fiber ring resonator to filter out up to 26 dB of excess laser intensity noise, resulting in a stabilized laser output that reaches the shot-noise limit over most of its signal spectrum.