Modulational instability and frequency combs in WGM microresonators with backscattering

TL;DR

This paper presents a first-principles model for frequency comb generation in WGM microresonators with backscattering, revealing how backscattering influences nonlinear resonance dynamics and enables modulational instability and soliton comb formation.

Contribution

The paper introduces the first detailed model accounting for backscattering effects in WGM microresonators, providing new insights into comb dynamics and instability mechanisms.

Findings

Backscattering causes splitting and reshaping of nonlinear resonances.

Backscattering induces modulational instability in the normal dispersion regime.

Novel soliton comb dynamics are driven by backward waves.

Abstract

We introduce the first principle model describing frequency comb generation in a WGM microresonator with the backscattering-induced coupling between the counter-propagating waves. {Elaborated model provides deep insight and accurate description of the complex dynamics of nonlinear processes in such systems.} We analyse the backscattering impact on the splitting and reshaping of the nonlinear resonances, demonstrate backscattering-induced modulational instability in the normal dispersion regime and subsequent frequency comb generation. We present and discuss novel features of the soliton comb dynamics induced by the backward wave.