Multimode opto-electro-mechanical transducer for high sensitive optical readout of electrical signals

An opto-electro-mechanical system formed by a nanomembrane capacitively coupled to an LC resonator and to an optical interferometer has been recently demonstrated for the high-sensitive optical readout of rf signals. We propose and experimentally demonstrate how the performance of such kind of transducer can be improved by controlling the interference between two electromechanical interaction pathways of a two-mode mechanical system. With a proof-of-principle device based operating at room temperature, we achieve a sensitivity of 10 nV/$\sqrt{{\rm Hz}}$ over a bandwidth of 5 kHz and a broader band sensitivity of 300 nV/$\sqrt{{\rm Hz}}$ over a bandwidth of 15 kHz. We discuss strategies for improving the performance of the device, showing that a mechanical multi-mode transducer can achieve a bandwidth larger than that of a single-mode one for the same given sensitivity. We derive a simple general relation between the bandwidth and the ultimate sensitivity of this class of transducers. We also underline that the interference at the basis of the increased bandwidth is the same allowing for a nonreciprocal feature of the device.
[1] I. Moaddel Haghighi et al., arXiv:1707.07562