On the modeling of thermal and free carrier nonlinearities in Silicon On Insulator microring resonators

TL;DR

This paper develops a refined model for silicon microring resonators that accurately captures thermal and free carrier nonlinearities, improving predictions over traditional methods and aiding the design of advanced photonic systems.

Contribution

It introduces a new temperature equation trained to match experimental data, addressing limitations of Newton's law of cooling in monolithic devices.

Findings

The refined model better predicts thermal dynamics in silicon resonators.

Traditional Newton's law can be inadequate for certain device configurations.

The model supports the development of neuromorphic photonic systems.

Abstract

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 relay on resonator dynamical states, such as all optical spiking neural networks or reservoirs for neuromorphic computing.