Soliton crystals in Kerr resonators

TL;DR

This paper reports the discovery and characterization of soliton crystals in Kerr microresonators, revealing their ordered structures, interactions, and potential applications in optical buffering and enhanced Kerr combs.

Contribution

It introduces the concept of soliton crystals in Kerr resonators, demonstrating their formation, properties, and implications for photonics and optical information processing.

Findings

Identification of soliton crystals via spectral interference patterns

Observation of crystallographic defects and their analysis

Confirmation of crystal structures through time-domain measurements

Abstract

Strongly interacting solitons confined to an optical resonator would offer unique capabilities for experiments in communication, computation, and sensing with light. Here we report on the discovery of soliton crystals in monolithic Kerr microresonators-spontaneously and collectively ordered ensembles of co-propagating solitons whose interactions discretize their allowed temporal separations. We unambiguously identify and characterize soliton crystals through analysis of their 'fingerprint' optical spectra, which arise from spectral interference between the solitons. We identify a rich space of soliton crystals exhibiting crystallographic defects, and time-domain measurements directly confirm our inference of their crystal structure. The crystallization we observe is explained by long-range soliton interactions mediated by resonator mode degeneracies, and we probe the qualitative difference between soliton crystals and a soliton liquid that forms in the absence of these interactions. Our work explores the rich physics of monolithic Kerr resonators in a new regime of dense soliton occupation and offers a way to greatly increase the efficiency of Kerr combs; further, the extreme degeneracy of the configuration space of soliton crystals suggests an implementation for a robust on-chip optical buffer.