High frequency nano-optomechanical disk resonators in liquids

TL;DR

This paper introduces nano-optomechanical semiconductor disk resonators capable of high-frequency operation in liquids, enabling ultrasensitive, rapid sensing of rheological properties despite dissipative challenges.

Contribution

It presents a novel nano-optomechanical approach using miniature disks that operate above GHz, with ultra-low mass and moderate dissipation, allowing direct optical resolution of vibrations in liquids.

Findings

High-sensitivity optical measurements resolve Brownian vibrations in liquids.

Resonators interact with liquids, providing rheological information.

Devices operate at frequencies above GHz with minimal dissipation.

Abstract

Vibrating nano- and micromechanical resonators have been the subject of research aiming at ultrasensitive mass sensors for mass spectrometry, chemical analysis and biomedical diagnosis. Unfortunately, their merits diminish dramatically in liquids due to dissipative mechanisms like viscosity and acoustic losses. A push towards faster and lighter miniaturized nanodevices would enable improved performances, provided dissipation was controlled and novel techniques were available to efficiently drive and read-out their minute displacement. Here we report on a nano-optomechanical approach to this problem using miniature semiconductor disks. These devices combine mechanical motion at high frequency above the GHz, ultra-low mass of a few picograms, and moderate dissipation in liquids. We show that high-sensitivity optical measurements allow to direct resolve their thermally driven Brownian vibrations, even in the most dissipative liquids. Thanks to this novel technique, we experimentally, numerically and analytically investigate the interaction of these resonators with arbitrary liquids. Nano-optomechanical disks emerge as probes of rheological information of unprecedented sensitivity and speed, opening applications in sensing and fundamental science.