Transition between Kerr comb and stimulated Raman comb in a silica whispering gallery mode microcavity

TL;DR

This paper explores how to control the transition between Kerr frequency combs and stimulated Raman scattering in silica microcavities, enabling selective switching between these states through experimental and theoretical analysis.

Contribution

It introduces a method to selectively switch between Kerr comb and Raman states in silica microcavities by controlling power, coupling, and detuning, based on gain competition analysis.

Findings

Raman-dominant region exists between Kerr comb transitions.

Stable Kerr and Raman states can be achieved by tuning parameters.

Experimental and theoretical results agree on the transition control mechanism.

Abstract

We theoretically and experimentally investigated the transition between modulation instability and Raman gain in a small silica microcavity with a large free-spectral range (FSR), which reveals that we can selectively switch from a four-wave mixing dominant state to a stimulated Raman scattering dominant state. Both the theoretical analysis and the experiment show that a Raman-dominant region is present between transitions of Kerr combs with different free-spectral range spacings. We can obtain a stable Kerr comb and a stable Raman state selectively by changing the driving power, coupling between the cavity and the waveguide, and laser detuning. Such a controllable transition is achieved thanks to the presence of gain competition between modulation instability and Raman gain in silica whispering gallery mode microcavities.