  The field of micro-cavity based frequency combs, or 'micro-combs'[1,2], has
recently witnessed many fundamental breakthroughs[3-19] enabled by the
discovery of temporal cavity-solitons, self-localised waves sustained by a
background of radiation usually containing 95% of the total power[20]. Simple
methods for their efficient generation and control are currently researched to
finally establish micro-combs as out-of-the-lab widespread tools[21]. Here we
demonstrate micro-comb laser cavity-solitons, an intrinsically
highly-efficient, background free class of solitary waves. Laser
cavity-solitons have underpinned key breakthroughs in semiconductor
lasers[22,23] and photonic memories[24-26]. By merging their properties with
the physics of both micro-resonators[1,2] and multi-mode systems[27], we
provide a new paradigm for the generation and control of self-localised pulses
in micro-cavities. We demonstrate 50 nm wide soliton combs induced with average
powers one order of magnitude lower than those typically required by
state-of-the-art approaches[26]. Furthermore, we can tune the repetition-rate
to well over a megahertz with no-active feedback.
