Phase-sensitive symmetry breaking in bidirectionally pumped Kerr microresonators

TL;DR

This paper explores how linear coupling affects symmetry breaking in bidirectionally pumped Kerr microresonators, revealing phase-sensitive control of nonlinear states with implications for advanced photonic sensors.

Contribution

It provides a combined theoretical and experimental analysis of phase-sensitive symmetry breaking influenced by linear intermode coupling in Kerr microresonators.

Findings

Linear coupling causes extreme sensitivity of intensity asymmetry to pump phase.

Symmetry breaking can be suppressed or enhanced depending on phase and coupling strength.

Threshold for symmetry breaking can be lowered with increased linear coupling.

Abstract

We demonstrate theoretically and experimentally that linear coupling due to the backscattering between two counterpropagating modes in a Kerr microresonator leads to extreme sensitivity of the intensity asymmetry of nonlinear light states to the relative phase between the bidirectional pumps of equal power. In the absence of linear coupling, the relative pump phase does not affect counterpropagating intraresonator intensities, and two asymmetric states arise due to spontaneous symmetry breaking. Contrariwise, in the presence of weak linear intermode coupling, the asymmetry of the states is deterministically controlled via changes in phase (for all phases except 0 and $\pi$). Spontaneous symmetry breaking at zero phase is suppressed when the linear intermode coupling is increased, while for the $\pi$ phase it can be enhanced, so that the overall threshold for the spontaneous symmetry breaking can be significantly lower for nonzero linear coupling. These results are important for fundamental understanding of the processes in Kerr resonators and other systems with Kerr-like nonlinearities and linear intermode coupling and have high prospects for the development of photonic devices such as ultrasensitive sensors.