Dynamics of mode-coupling-induced microresonator frequency combs in normal dispersion

TL;DR

This paper explores how mode coupling influences the generation of frequency combs in microresonators with normal dispersion, revealing mechanisms for initiating modulation instability and forming low-noise combs, with implications for broadband comb development.

Contribution

It provides a combined experimental and theoretical analysis of mode-coupling effects on frequency comb dynamics in the normal GVD regime, extending existing models and understanding.

Findings

Mode coupling can trigger intracavity modulation instability in normal GVD microresonators.

A low-noise frequency comb forms as the pump is tuned further into resonance.

Phase-matching conditions accurately predict MI and comb spectral features.

Abstract

We experimentally and theoretically investigate the dynamics of microresonator-based frequency comb generation assisted by mode coupling in the normal group-velocity dispersion (GVD) regime. We show that mode coupling can initiate intracavity modulation instability (MI) by directly perturbing the pump-resonance mode. We also observe the formation of a low-noise comb as the pump frequency is tuned further into resonance from the MI point. We determine the phase-matching conditions that accurately predict all the essential features of the MI and comb spectra, and extend the existing analogy between mode coupling and high-order dispersion to the normal GVD regime. We discuss the applicability of our analysis to the possibility of broadband comb generation in the normal GVD regime.