High-Q silicon optomechanical microdisk resonators at gigahertz frequencies

TL;DR

This paper presents silicon optomechanical microdisk resonators operating at frequencies up to 1.75 GHz, demonstrating high mechanical quality factors and sensitive optical transduction of thermal motion in ambient conditions.

Contribution

It introduces high-Q silicon microdisk resonators at gigahertz frequencies with detailed analysis of modal coupling and optimized pedestal design for enhanced Q factors.

Findings

Achieved a maximum mechanical Q of 4370 at 1.47 GHz in ambient air.

Demonstrated displacement sensitivity of 4.1 × 10^(-17) m/Hz^(1/2).

Numerical simulations guide pedestal size for optimal Q.

Abstract

We report disk-shaped silicon optomechanical resonators with frequency up to 1.75 GHz in the ultrahigh frequency band. Optical transduction of the thermal motion of the disks' in-plane vibrational modes yields a displacement sensitivity of 4.1 \times 10^(-17) m/Hz^(1/2). Due to the reduced clamping loss, these disk resonators possess high mechanical quality factors (Q), with the highest value of 4370 for the 1.47 GHz mode measured in ambient air. Numerical simulation on the modal frequency and mechanical Q for disks of varying undercut shows modal coupling and suggests a realistic pedestal size to achieve the highest possible Q.