Strong 4-mode coupling of nanomechanical string resonators

TL;DR

This paper demonstrates strong coupling between four fundamental vibrational modes of two silicon-nitride nanomechanical string resonators, achieved through strain-mediated interactions and dielectric control, enabling complex multimode resonance phenomena.

Contribution

It introduces a method to induce and control strong 4-mode coupling in nanomechanical resonators via strain and dielectric tuning, revealing multimode resonance effects.

Findings

Strong mechanical coupling between resonators via shared clamping.

Observation of multimode avoided crossing phenomena.

Control of mode coupling through dielectric actuation.

Abstract

We investigate mechanical mode coupling between the four fundamental flexural modes of two doubly-clamped, high-Q silicon-nitride nanomechanical string resonators. Strong mechanical coupling between the strings is induced by the strain mediated via a shared clamping point, engineered to increase the exchange of oscillatory energy. One of the resonators is controlled dielectrically, which results in strong coupling between its out-of-plane and in-plane flexural modes. We show both, inter-string out-of-plane-in-plane and 3-mode resonance of the four coupled fundamental vibrational modes of a resonator pair, giving rise to a simple and a multimode avoided crossing, respectively.