Observation of Bound States of Parametrically-Driven Kerr Cavity Solitons

Cavity solitons (CSs) are stable pulses emerging in Kerr resonators, resulting from a double balance between dispersion and Kerr non-linearity on the one hand and driving and loss on the other [1]. These localized wave packets are stable system attractors and display rich dynamics such as oscillatory behavior or the formation of bound states where multiple solitons coexist in a fixed relative arrangement [2]. It was recently shown that CSs can be hosted in degenerate optical parametric oscillators (OPO). In this configuration, there is no background (the pump is at twice the soliton carrier frequency) and two attractors, with phase differences of π may coexist [3]–[6]. Despite these observations and the strong potential for applications [7], bound states of PDCSs [8] have never been observed in quadratic OPOs.