Kerr-Induced Noise Quenching in Pulse Pumped Microcavity Solitons

Soliton mode locking in microresonators enables chip-scale generation of low-noise optical and microwave signals. Pulse pumped solitons offer a platform for broadband microcomb generation with stabilized repetition rates and for exploring soliton physics. In this Letter, we present a theoretical and experimental investigation of Kerr-induced phase noise quenching (KINQ) in pulse pumped solitons. We derive a model that quantifies the locking bandwidth between the soliton and the pump pulse and reveals the mechanism of KINQ. Experiments in a silica microresonator show up to ∼20  dB of phase noise suppression from the pump. The lowest noise is achieved by tuning the pump repetition rate to expand the soliton existence range and operating near, but not at, its upper boundary of this range. Our results establish a theory for solitons trapped by a nonuniform background and offer guidelines for attaining low-noise states in coherently pumped systems.