On the modeling of thermal and free carrier nonlinearities in silicon-on-insulator microring resonators

The temporal dynamics of integrated silicon resonators has been modeled using a set of equations coupling the internal energy, the temperature and the free carrier population. Owing to its simplicity, Newton's law of cooling is the traditional choice for describing the thermal evolution of such systems. In this work, we theoretically and experimentally prove that this can be inadequate in monolithic planar devices, leading to inaccurate predictions. A new equation that we train to reproduce the correct temperature behaviour is introduced to fix the discrepancies with the experimental results. We discuss the limitations and the range of validity of our refined model, identifying those cases where Netwon's law provides, nevertheless, accurate solutions. Our modeling describes the phenomena underlying thermal and free carrier instabilities and is a valuable tool for the engineering of photonic systems which rely on resonator dynamical states, such as all optical spiking neural networks or reservoirs for neuromorphic computing. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

The traditional Newton's law of cooling may be inadequate in describing the thermal evolution of integrated silicon resonators, but a new equation introduced in this study can fix the inaccuracies. The research discusses the limitations and range of validity of the refined model, while identifying cases where Newton's law still provides accurate solutions. The modeling is valuable for understanding thermal and free carrier instabilities, and for engineering photonic systems relying on resonator dynamical states.