Sensitivity-bandwidth limit in a multi-mode opto-electro-mechanical transducer

TL;DR

This paper demonstrates how controlling interference in a multi-mode opto-electro-mechanical transducer can significantly increase its bandwidth while maintaining high sensitivity, with experimental validation at room temperature.

Contribution

It introduces a method to enhance transducer bandwidth by interference control in a two-mode mechanical system, validated through experimental proof-of-principle results.

Findings

Achieved 15 kHz bandwidth with 300 nV/Hz^{1/2} sensitivity

Attained 5 kHz bandwidth at shot-noise limit with 10 nV/Hz^{1/2} sensitivity

Showed multi-mode transducers can outperform single-mode devices in bandwidth for the same sensitivity

Abstract

An opto--electro--mechanical system formed by a nanomembrane capacitively coupled to an LC resonator and to an optical interferometer has been recently employed for the high--sensitive optical readout of radio frequency (RF) signals [T. Bagci, \emph{et~al.}, Nature {\bf 507}, 81 (2013)]. Here we propose and experimentally demonstrate how the bandwidth of such kind of transducer can be increased by controlling the interference between two--electromechanical interaction pathways of a two--mode mechanical system. With a proof--of--principle device \new{operating at room temperature, we achieve a sensitivity of 300 nV/Hz^(1/2) over a bandwidth of 15 kHz in the presence of radiofrequency noise, and an optimal shot-noise limited sensitivity of 10 nV/Hz^(1/2) over a bandwidth of 5 kHz. We discuss strategies for improving the performance of the device, showing that, for the same given sensitivity, a mechanical multi--mode transducer can achieve a bandwidth} significantly larger than that of a single-mode one.