Design of Dispersive Interferometers for the Self-Stabilization of Optical Frequency Combs

A promising approach for photonic-chip-based ultra-low-phase-noise microwave generation is to stabilize an optical frequency comb (OFC) using active feedback from a short-delay asymmetric interferometer. Previously, indirect evidence indicated that the microwave phase noise was limited by dispersion in the interferometer that reduced the interferometer’s sensitivity, ηrep, to the OFC’s repetition rate. No direct evidence was shown. Here, we compare direct measurements of ηrep in interferometers using single-mode and dispersion-shifted fibers (SMF and DSF). With SMF, ηrep was approximately 30% of the value that we measured with DSF, corresponding to a change in microwave phase noise of up to 10 dB.