Superspontaneous Four-Wave Mixing in an Array of Silicon Microresonators

Composite optical systems can show compelling collective dynamics. For instance, the cooperative decay of quantum emitters into a common radiation mode can lead to super-radiance, where the emission rate of the ensemble is larger than the sum of the rates of the individual emitters. Here, we report experi-mental evidence of super spontaneous four-wave mixing, an analogous effect for the generation of photon pairs in a parametric nonlinear process on an integrated photonic device. We study this phenomenon in an array of microring resonators on a silicon photonic chip coupled to bus waveguides. We measure a cooperative pair-generation rate that always exceeds the incoherent sum of the rates of the individual res-onators. We investigate the physical mechanisms underlying this collective behavior, clarify the impact of loss, and address the aspects of fundamental and technological relevance of our results.