Femtogram Doubly Clamped Nanomechanical Resonators Embedded in a High-Q Two-Dimensional Photonic Crystal Nanocavity

TL;DR

This paper presents a novel optomechanical system embedding femtogram nanobeam resonators in a high-Q photonic crystal cavity, enabling highly sensitive room-temperature transduction of GHz mechanical modes.

Contribution

The work introduces a new

Findings

Achieved displacement sensitivity of 0.94 fm/Hz^(1/2)

Demonstrated room-temperature optical transduction of 1 GHz mechanical modes

Highlighted the importance of structural symmetry for high Q factors

Abstract

We demonstrate a new optomechanical device system which allows highly efficient transduction of femtogram nanobeam resonators. Doubly clamped nanomechanical resonators with mass as small as 25 fg are embedded in a high-finesse two-dimensional photonic crystal nanocavity. Optical transduction of the fundamental flexural mode around 1 GHz was performed at room temperature and ambient conditions, with an observed displacement sensitivity of 0.94 fm/Hz^(1/2). Comparison of measurements from symmetric and asymmetric double-beam devices reveals hybridization of the mechanical modes where the structural symmetry is shown to be the key to obtain a high mechanical quality factor. Our novel configuration opens the way for a new category of "NEMS-in-cavity" devices based on optomechanical interaction at the nanoscale.