Super-efficient temporal solitons in mutually coupled optical cavities

A coherently driven Kerr optical cavity is able to sustain dissipative temporal solitons, enabling all-optical data storage buffers and broadband frequency combs. Kerr solitons are balanced through an energy exchange with the pump field. Improving the pump-to-soliton energy conversion is of great importance for practical applications, but remains an outstanding challenge owing to a limited pump–soliton temporal overlap. Here we report the discovery of temporal solitons in mutually coupled cavities instead of a traditional single cavity. A pump recycling strategy is proposed, to greatly improve the power utilization efficiency. Using macroscale optical fibre-ring cavities, which share the same physical model as miniature microresonators, we demonstrate nearly 100% pump recycling and the ability to break the efficiency limit of a single cavity. This study could greatly extend the applications of temporal cavity solitons and provides an attractive platform for exploring the complex nonlinear dynamics in coupled cavity systems