# Heteronuclear soliton molecules in optical microresonators

## TL;DR

This paper reports the discovery of heteronuclear dissipative Kerr soliton molecules in optical microresonators, revealing complex bound states of dissimilar solitons with potential applications in metrology and spectroscopy.

## Contribution

It introduces heteronuclear soliton molecules in Kerr microresonators, a novel state of bound solitons with dissimilar properties, expanding understanding of soliton interactions in nonlinear systems.

## Key findings

- Heteronuclear soliton molecules are tightly bound despite differences in soliton properties.
- Ultrafast sampling reveals short-range binding of dissimilar solitons.
- Generated frequency combs have unusual mode structures useful for applications.

## Abstract

Optical soliton molecules are bound states of solitons that arise from the balance between attractive and repulsive effects. Having been observed in systems ranging from optical fibers to mode-locked lasers, they provide insights into the fundamental interactions between solitons and the underlying dynamics of the nonlinear systems. Here, we enter the multistability regime of a Kerr microresonator to generate superpositions of distinct soliton states that are pumped at the same optical resonance, and report the discovery of heteronuclear dissipative Kerr soliton molecules. Ultrafast electrooptical sampling reveals the tightly short-range bound nature of such soliton molecules, despite comprising dissipative Kerr solitons of dissimilar amplitudes, durations and carrier frequencies. Besides the significance they hold in resolving soliton dynamics in complex nonlinear systems, such heteronuclear soliton molecules yield coherent frequency combs whose unusual mode structure may find applications in metrology and spectroscopy.