Lasing on hybridized soliton frequency combs

TL;DR

This paper demonstrates a chip-scale coupled laser system that produces complex hybridized frequency combs with simultaneous bright and dark solitons, revealing new states of light enabled by coupling.

Contribution

It introduces a novel coupled semiconductor laser system that generates hybridized frequency combs with unique soliton states, not achievable in uncoupled lasers.

Findings

Formation of hybridized frequency combs in coupled lasers

Observation of simultaneous bright and dark solitons

Breathing soliton states in coupled laser cavities

Abstract

Coupling is an essential mechanism that drives complexity in natural systems, transforming single, non-interacting elements into intricate networks with rich physical properties. Here, we demonstrate a chip-scale coupled laser system that exhibits complex optical states impossible to achieve in an uncoupled system. We show that a pair of coupled semiconductor ring lasers spontaneously forms a frequency comb consisting of the hybridized modes of its coupled cavity, exhibiting a large number of phase-locked tones that anticross with one another. Experimental coherent waveform reconstruction reveals that the hybridized frequency comb manifests itself as pairs of bright and dark picosecond-long solitons circulating simultaneously. The dark and bright solitons exit the coupled cavity at the same time, leading to breathing bright solitons temporally overlapped with their dark soliton counterparts - a state inaccessible for a single, free-running laser. Our results demonstrate that the rules that govern allowable states of light can be broken by simply coupling elements together, paving the way for the design of more complex networks of coupled on-chip lasers.