Synchronization of silicon thermal free-carrier oscillators

Abstract

Recent exploration of collective phenomena in oscillator arrays has highlighted the potential to access a range of physical phenomena, from fundamental quantum many-body dynamics to the solution of practical optimization problems using photonic Ising machines. Spontaneous oscillations often arise in these oscillator arrays as an imbalance between gain and loss. Due to coupling between individual arrays, the spontaneous oscillation is constrained and leads to interesting collective behavior, such as synchronized oscillations in optomechanical oscillator arrays, ferromagnetic-like coupling in delay-coupled optical parametric oscillators, and binary phase states in coupled laser arrays. A key aspect of arrays is not only the coupling between the individuals but also their compliance toward neighbor stimuli. One self-sustaining photonic oscillator that can be readily implemented in a scalable foundry-based technology is based on the interaction of free carriers, temperature, and the optical field of a resonant silicon photonic microcavity. Here, we demonstrate that these silicon thermal free-carrier (FC) oscillators are extremely compliant to external excitation and can be synchronized up to their 16th harmonic using a weak seed. Exploring this unprecedented compliance to external stimuli, we also demonstrate robust synchronization between two thermal FC oscillators.