摘要： Optical frequency combs based on micro-cavity resonators, also known as ‘micro-combs’, are ready to achieve the full capability of their bulk counterparts but on an integrated footprint [1]. They have enabled major breakthroughs in spectroscopy, communications, microwave photonics, frequency synthesis, optical ranging, quantum sources and metrology. Of particular relevance was the recent experimental implementation of temporal cavity-solitons [2,3]. Temporal cavity-solitons in micro-resonators are described by the well-known Lugiato-Lefever equation. Currently, these self-localised waves form on top of a strong background of radiation, usually containing 95% of the total power [4] and require active control of an external driving laser – a complex process which limits the choice of fundamental parameters such as the repetition-rate. Developing simple methods for controlling and generating highly efficient, self-localised pulses is one of the most compelling challenges to overcome, in anticipation of the widespread use of micro-combs outside of laboratory environments. Here we report the discovery of micro-comb laser cavity-solitons, which are the most efficient class of cavity-solitons because they are intrinsically background-free. Laser cavity-solitons have previously underpinned major breakthroughs in other systems, e.g. for the realisation of efficient semiconductor lasers [5]. By merging their properties with the physics of both micro-resonators and multi-mode systems, we provide a fundamentally new paradigm for the generation, stabilisation and control of self-localised optical pulses in micro-cavities. Our design is inspired to the filter-driven four-wave mixing scheme [6], which is based on a nonlinear micro-cavity nested in a larger fibre-cavity loop. We demonstrate 50 nm wide soliton combs induced with average powers more than one order of magnitude lower than those typically used in state-of-the-art soliton micro-combs [1]. Very importantly, in stark contrast to temporal cavity-solitons based on passive Lugiato-Lefever systems, our bright laser cavity solitons are background-free, and we achieve a mode-efficiency [4] above 75%, compared to typical 1% - 5% for bright solitons realised with standard approaches. Furthermore, we can tune the repetition-rate to well over a megahertz with no-active control.