Transient Regime of Kerr Frequency Comb Formation

TL;DR

This paper investigates the transient formation of Kerr frequency combs in microresonators, revealing that combs grow from vacuum fluctuations over extended timescales and exhibit intrinsic modelocking due to sequential four-wave mixing.

Contribution

It provides experimental and numerical insights into the transient dynamics and intrinsic modelocking mechanisms of Kerr frequency comb formation in microresonators.

Findings

Comb emerges from vacuum fluctuations over timescales longer than the resonator's ringdown time.

Frequency harmonics spread from the pumped mode in anomalous dispersion microresonators.

Different growth rates of harmonics result from sequential four-wave mixing, explaining modelocking.

Abstract

Temporal growth of an optical Kerr frequency comb generated in a microresonator is studied both experimentally and numerically. We find that the comb emerges from vacuum fluctuations of the electromagnetic field on timescales significantly exceeding the ringdown time of the resonator modes. The frequency harmonics of the comb spread starting from the optically pumped mode if the microresonator is characterized with anomalous group velocity dispersion. The harmonics have different growth rates resulting from sequential four-wave mixing process that explains intrinsic modelocking of the comb.