Tuning and Stabilization of Optomechanical Crystal Cavities Through NEMS Integration

TL;DR

This paper demonstrates electrostatic tuning and stabilization of nanobeam optomechanical crystal cavities by integrating NEMS actuators, enabling precise control of optical resonance with minimal quality factor degradation.

Contribution

The work introduces a novel NEMS integration approach for tuning and stabilizing optomechanical cavities, achieving wide tuning ranges and feedback control.

Findings

Optical wavelength tuning across several linewidths with high Q factor

Resonance frequencies of actuators in the 10-20 MHz range

Successful feedback stabilization of optical resonance

Abstract

Nanobeam optomechanical crystals, in which localized GHz frequency mechanical modes are coupled to wavelength-scale optical modes, are being employed in a variety of experiments across different material platforms. Here, we demonstrate the electrostatic tuning and stabilization of such devices, by integrating a Si$_3$N$_4$ slot-mode optomechanical crystal cavity with a nanoelectromechanical systems (NEMS) element, which controls the displacement of an additional "tuning" beam within the optical near-field of the optomechanical cavity. Under DC operation, tuning of the optical cavity wavelength across several optical linewidths with little degradation of the optical quality factor ($Q\approx10^5$) is observed. The AC response of the tuning mechanism is measured, revealing actuator resonance frequencies in the 10 MHz to 20 MHz range, consistent with the predictions from simulations. Feedback control of the optical mode resonance frequency is demonstrated, and alternative actuator geometries are presented.