Short-length homodyne interferometer for self-stabilization of an optical frequency comb

Abstract

We stabilized the repetition rate of an optical frequency comb with a self-referenced phase-locked loop that used a short-path-length fiber-optic interferometer to generate its error signal. In this work, we used a homodyne interferometer instead of a heterodyne interferometer, so that the architecture of the phase-locked loop was simpler than our previous implementation. We used the stabilized repetition rate to generate a 10-GHz signal with a phase noise of -120 dBc/Hz at an offset frequency of 1 kHz. The simplified architecture and the short path length imbalance of the interferometer would allow it to be fabricated on an all-passive silicon chip and may lead to a chip-scale optical frequency comb with an ultra-low-noise repetition rate.