Nonlinear spectral translation and injection locking of electro-optic combs in light-atom interfaces

We demonstrate injection locking of Fabry–Perot lasers to electro-optic (EO) frequency combs using comb powers as low as 1 nW, more than two orders of magnitude below the levels required for semiconductor optical amplification. This approach extends EO comb spectral translation from the telecom band to 780 nm via second-harmonic generation in silicon nitride microring resonators. We further generate EO combs at 420 nm by translating 780 nm combs through a four-wave-mixing process in rubidium vapor. Integrating these techniques paves the way toward chip-scale cascaded frequency conversion from the telecom band into the blue, providing compact and scalable light sources for quantum technologies.