Microcombs for Optical Communications

Microcombs harness the Kerr nonlinear effect in a high-Q microresonator to generate an array of phase-locked frequency lines derived from a continuous-wave laser [1]. The line spacing in a microcomb is compatible with the channel spacing in wavelength division multiplexing (WDM) used in fiber-optic communication systems [2]. In this tutorial, I will give a historical overview of how frequency combs have been utilized in WDM [3] and discuss the possibilities in modern coherent systems enabled by their phase coherence [4]. Recent advances in heterogeneous integration of microcombs, power-efficient microcomb architectures [5], [6] and demonstrations in space division multiplexing will be highlighted [7].