Soliton Auto-generation Within Kerr Resonators under Pulsed-driving

Dissipative temporal Kerr cavity solitons (CSs) are ultra-short pulses of light that can circulate indefinitely and without distortion within an optical cavity [1]. Over recent years they have attracted considerable attention thanks to a suite of applications being demonstrated from real-time spectroscopy to ultra-fast ranging [2]. With the commercial potential of this technology beginning to be realised, there has been a push towards tackling practical issues, chief among them being the reliable and robust generation of CSs. In this contribution, we demonstrate within a pulse-driven Kerr resonator that there exists a novel regime of CS auto-generation in which the CS state is the only available optical state of the system. Operating in this regime not only provides the CS states an enhanced level of robustness to environmental factors, but also guarantees the direct and automatic generation of CSs from an empty cavity without the need of any external seed or parameter ramp (i.e., soft excitation). Experimentally, our setup is comprised of a 0.3 m length of dispersion-shifted fiber with two dielectric end caps creating a Fabry-Perot cavity. The cavity is driven with a periodic train of 1.6-ps-long pulses created via standard electro-optic means [1], and with the help of a weak control beam we can precisely control the cavity detuning over the whole free-spectral range. Figure 1(a) illustrates this CS auto-generation with a pseudo-coloured plot of the intracavity spectrum as we periodically turn our picosecond driving pulse off and on again, showing the intracavity field automatically evolve into a CS from noise given that the cavity parameters lie within the auto-generative regime. A single trace of the experimental CS spectrum is shown in Fig. 1(b) in red (with the prominent spectral peak corresponding to a phase-matched dispersive wave), overlaid with a numerical simulation obtained with the same parameters (with the inset showing the temporal intensity profile) using the governing Lugiato-Lefever model [1]. Furthermore, due to the interplay between higher-order dispersion and our pulsed driving field, the deterministic selection of CS bound-states [3] becomes possible by simply tuning cavity parameters such as the pump desynchronisation or cavity detuning.