Linear and Nonlinear Coupling of Light in Twin-Resonators with Kerr Nonlinearity

TL;DR

This paper investigates the effects of Kerr nonlinearity on the coupling behavior of twin microresonators, revealing tunable mode splitting and spontaneous symmetry breaking at high powers, supported by experimental and theoretical analysis.

Contribution

It provides the first detailed experimental and theoretical study of linear and nonlinear coupling effects in Kerr-nonlinear twin microresonators.

Findings

Linear coupling causes tunable mode splitting at low powers.

High powers induce spontaneous symmetry breaking in the resonances.

Experimental results align with the theoretical model.

Abstract

Nonlinear effects in microresonators are efficient building blocks for all-optical computing and telecom systems. With the latest advances in microfabrication, coupled microresonators are used in a rapidly growing number of applications. In this work, we investigate the coupling between twin-resonators in the presence of Kerr-nonlinearity. We use an experimental setup with controllable coupling between two high-Q resonators and discuss the effects caused by the simultaneous presence of linear and non-linear coupling between the optical fields. Linear-coupling-induced mode splitting is observed at low input powers, with the controllable coupling leading to a tunable mode splitting. At high input powers, the hybridized resonances show spontaneous symmetry breaking (SSB) effects, in which the optical power is unevenly distributed between the resonators. Our experimental results are supported by a detailed theoretical model of nonlinear twin-resonators. With the recent interest in coupled resonator systems for neuromorphic computing, quantum systems, and optical frequency comb generation, our work provides important insights into the behavior of these systems at high circulating powers.