Laser cavity-soliton microcombs

Microcavity-based frequency combs, or ‘microcombs’, have enabled many fundamental breakthroughs through the discovery of temporal cavity-solitons. These self-localized waves, described by the Lugiato–Lefever equation, are sustained by a background of radiation usually containing 95% of the total power. Simple methods for their efficient generation and control are currently being investigated to finally establish microcombs as out-of-the-lab tools. Here, we demonstrate microcomb laser cavity-solitons. Laser cavity-solitons are intrinsically background-free and have underpinned key breakthroughs in semiconductor lasers. By merging their properties with the physics of multimode systems, we provide a new paradigm for soliton generation and control in microcavities. We demonstrate 50-nm-wide bright soliton combs induced at average powers more than one order of magnitude lower than the Lugiato–Lefever soliton power threshold, measuring a mode efficiency of 75% versus the theoretical limit of 5% for bright Lugiato–Lefever solitons. Finally, we can tune the repetition rate by well over a megahertz without any active feedback.