Efficient Generation of a Near-visible Frequency Comb via Cherenkov-like Radiation from a Kerr Microcomb

Optical frequency combs are widely used in precision metrology, communication, and sensing. Though highly desired for biosensing and interconnection with atomic systems, on-chip generation of combs near visible-light frequencies is severely limited by high losses. This study uses coexisting optical nonlinearities in an AlN microring resonator to generate a near-visible frequency comb with surprising efficiency (up to 22%). The approach could be extended to other frequency ranges as well.