Optical Kerr soliton microcombs for high bandwidth communications

Microcombs, optical frequency combs generated by nonlinear integrated micro-cavity resonators, have the potential to offer the full capability of their benchtop comb based counterparts, but in an integrated footprint. They have enabled breakthroughs in spectroscopy, microwave photonics, frequency synthesis, optical ranging, quantum state generation and manipulation, metrology, optical neuromorphic processing and more. One of their most promising applications has been optical fibre communications where they have formed the basis for massively parallel ultrahigh capacity multiplexed data transmission. Innovative approaches have been used in recent years to phaselock, or modelock different types of microcombs, from dissipative Kerr solitons to dark solitons, soliton crystals and others. This has enabled their use as sources for optical communications including advanced coherent modulation format systems that have achieved ultrahigh data capacity bit rates breaking the petabit/s barrier. Here, we review this new and exciting field, chronicling the progress while highlighting the challenges and opportunities.