Direct Temporal Measurement of Switching-Waves in a Normal Dispersion Kerr Resonator

The ability of Kerr resonators to generate high-quality frequency combs has attracted significant attention [1]. Combs operated in resonators with normal dispersion have been shown to possess attractive characteristics including both high conversion efficiency and spectral flatness [2]. The underlying nonlinear dissipative structures responsible for the formation of these normal dispersion combs are known as switching-waves (SWs) [3]. In the context of Kerr resonators, SWs provide a local connection between the two homogeneous levels of a bistable cavity. A pair of interlocked SWs thus allows the formation of stable dark pulses, with the bandwidth of the resultant comb set by the (temporal) durations of the two SWs [3]. In this abstract we present the direct temporal measurement of the profile of a SW for a wide range of cavity conditions. This allows us to experimentally measure the oscillation frequency and decay rate of the SW's tail, and compare these temporal observations to both spectral measurements of the associated dispersive wave (DW), and predictions of a simple phasematching analysis [4]. This enables us to fully characterise the properties of the SW as a function of the cavity parameters.