Cascaded injection locking of optomechanical crystal oscillators

TL;DR

This paper demonstrates cascaded injection locking of silicon-based optomechanical crystal oscillators via a weak mechanical link, enabling synchronized operation for scalable photonic integrated circuits and future phonon-photon hybrid networks.

Contribution

It introduces a novel cascaded injection locking method for optomechanical oscillators using mechanical coupling, facilitating scalable synchronization in integrated photonic systems.

Findings

Successful demonstration of cascaded injection locking in silicon optomechanical cavities.

Mechanical coupling enables synchronization without relying solely on optical interactions.

Supports development of large-scale phonon-photon hybrid circuits.

Abstract

Optomechanical oscillators stand out as high-performance and versatile candidates for serving as reference clocks in sequential photonic integrated circuits. Indeed, they have the unique capability of simultaneously generating mechanical tones and optical signal modulations at frequencies determined by their geometrical design. In this context, the concept of synchronization introduces a powerful means to precisely coordinate the dynamics of multiple oscillators in a controlled manner, thus increasing efficiency and preventing errors in signal processing photonic systems or communication interfaces. In this work, we demonstrate the cascaded injection locking of a pair of silicon-based optomechanical crystal cavities to an external reference signal that subtly modulates the laser driving one of the oscillators. Both cavities interact solely through a weak mechanical link, making the extension of this synchronization mechanism to an increased number of optomechanical oscillators within a common chip more feasible than relying solely on optical interactions. Thus, the combination of the obtained results, supported by a numerical model, with remote optical injection locking schemes discussed in the literature, lays the groundwork for the distribution of reference signals within large networks of processing elements in future phonon-photon hybrid circuits.