High-order coherent communications using mode-locked dark-pulse Kerr combs from microresonators

TL;DR

This paper demonstrates high-order coherent optical communications using dark-pulse Kerr combs from microresonators, achieving high signal quality with efficient power use in a novel comb state.

Contribution

It presents the first coherent transmission experiments with dark-pulse Kerr combs, showcasing their potential for advanced fiber-optic communication systems.

Findings

Achieved optical SNR above 33 dB with 64-QAM modulation.

Demonstrated compatibility with hybrid silicon lasers.

Validated dark-pulse combs as effective multi-wavelength sources.

Abstract

Microresonator frequency combs harness the nonlinear Kerr effect in an integrated optical cavity to generate a multitude of phase-locked frequency lines. The line spacing can reach values in the order of 100 GHz, making it an attractive multi-wavelength light source for applications in fiber-optic communications. Depending on the dispersion of the microresonator, different physical dynamics have been observed. A recently discovered comb state corresponds to the formation of mode-locked dark pulses in a normal-dispersion microcavity. Such dark-pulse combs are particularly compelling for advanced coherent communications since they display unusually high power conversion efficiency. Here, we report the first coherent transmission experiments using 64-quadrature amplitude modulation encoded onto the frequency lines of a dark-pulse comb. The high conversion efficiency of the comb enables transmitted optical signal-to-noise ratios above 33 dB while maintaining a laser pump power level compatible with state-of-the-art hybrid silicon lasers.