# Universal mechanism for the binding of temporal cavity solitons

## TL;DR

This paper uncovers a universal mechanism for the formation of long-range bound states of temporal cavity solitons in Kerr resonators, driven by spectral perturbations that induce resonant tails, supported by experiments and theoretical models.

## Contribution

It introduces a universal mechanism explaining how perturbations lead to stable long-range soliton binding in Kerr resonators, supported by experimental and theoretical evidence.

## Key findings

- Experimental observation of long-range bound states in fiber ring cavities.
- Identification of three different perturbations causing soliton binding.
- Good agreement between experiments and new vector mean-field model.

## Abstract

We present theoretical and experimental evidence of a universal mechanism through which temporal cavity solitons of externally-driven, passive, Kerr resonators can form robust long-range bound states. These bound states, sometime also referred to as multi-soliton states or soliton crystals in microresonators, require perturbations to the strict Lugiato-Lefever mean field description of temporal cavity solitons. Binding occurs when the perturbation excites a narrowband resonance in the soliton spectrum, which gives long oscillatory tails to the solitons. Those tails can then interlock for a discrete set of temporal separations between the solitons. The universality of this mechanism is demonstrated in fiber ring cavities by providing experimental observations of long-range bound states ensuing from three different perturbations: third-order dispersion (dispersive wave generation), the periodic nature of the cavity (Kelly sidebands), and the random birefringence of the resonator. Sub-picosecond resolution of bound state separations and their dynamics are obtained by using the dispersive Fourier transform technique. Good agreement with theoretical models, including a new vector mean-field model, is also reported.