Tunable exciton-optomechanical coupling in suspended monolayer MoSe2

TL;DR

This paper demonstrates tunable exciton-optomechanical coupling in suspended monolayer MoSe2, showing optical damping, anti-damping, and spring effects, with potential applications in NEMS and exciton-optomechanics.

Contribution

It reports the first observation of gate-tunable exciton-optomechanical coupling in a monolayer TMD, combining optical control with mechanical resonators.

Findings

Optical damping and anti-damping of mechanical vibrations.

Gate-tunable exciton-optomechanical coupling strength.

Observation of optical spring effect in MoSe2 resonator.

Abstract

The strong excitonic effect in monolayer transition metal dichalcogenide (TMD) semiconductors has enabled many fascinating light-matter interaction phenomena. Examples include strongly coupled exciton-polaritons and nearly perfect atomic monolayer mirrors. The strong light-matter interaction also opens the door for dynamical control of mechanical motion through the exciton resonance of monolayer TMDs. Here we report the observation of exciton-optomechanical coupling in a suspended monolayer MoSe2 mechanical resonator. By moderate optical pumping near the MoSe2 exciton resonance, we have observed optical damping and anti-damping of mechanical vibrations as well as the optical spring effect. The exciton-optomechanical coupling strength is also gate-tunable. Our observations can be understood in a model based on photothermal backaction and gate-induced mirror symmetry breaking in the device structure. The observation of gate-tunable exciton-optomechanical coupling in a monolayer semiconductor may find applications in nanoelectromechanical systems (NEMS) and in exciton-optomechanics.