Silicon anisotropy in a bi-dimensional optomechanical cavity

TL;DR

This study investigates how silicon's mechanical anisotropy influences the behavior of a 2D optomechanical crystal, revealing orientation-dependent effects on mechanical spectra and coupling, and demonstrating cryogenic operation.

Contribution

It provides experimental insights into the impact of silicon anisotropy on 2D optomechanical devices, including fabrication and cryogenic performance analysis.

Findings

Device orientation affects mechanical band structure

Mechanical anisotropy influences optomechanical coupling

Device achieves ground state occupancy of 0.2 phonons at mK temperatures

Abstract

In this work, we study the effects of mechanical anisotropy in a 2D optomechanical crystal geometry. We fabricate and measure devices with different orientations, showing the dependence of the mechanical spectrum and the optomechanical coupling with the relative angle of the device to the crystallography directions of silicon. Our results show that the device orientation strongly affects its mechanical band structure, which makes the devices more susceptible to fabrication imperfections. Finally, we show that our device is compatible with cryogenic measurements reaching ground state occupancy of 0.2 phonons at mK temperature.