# Multicolor interband solitons in microcombs

## TL;DR

Researchers observed multicolor solitons in microcombs using interband coupling, enabling synchronized pulses with the same repetition rate.

## Contribution

The first experimental observation of multicolor solitons using interband coupling in a compound resonator.

## Key findings

- Multicolor solitons were generated from a single optical pump in a compound resonator.
- The pulses share the same repetition rate and may be fully phase-locked.
- Interband coupling enabled the phenomenon under experimentally feasible dispersion conditions.

## Abstract

In microcombs, solitons can drive non-soliton-forming modes to induce optical gain. Under specific conditions, a regenerative secondary temporal pulse coinciding in time and space with the exciting soliton pulse will form at a new spectral location. A mechanism involving Kerr-induced pulse interactions has been proposed theoretically, leading to multicolor solitons containing constituent phase-locked pulses. However, the occurrence of this phenomenon requires dispersion conditions that are not naturally satisfied in conventional optical microresonators. Here, we report the experimental observation of multicolor pulses from a single optical pump in a way that is closely related to the concept of multicolor solitons. The individual soliton pulses share the same repetition rate and could potentially be fully phase-locked. They are generated using interband coupling in a compound resonator.