Molecular-optomechanical phonon laser

TL;DR

This paper proposes a molecular cavity optomechanics system for a mid-infrared phonon laser with ultra-low threshold power, enabled by strong single-photon coupling and molecular effects.

Contribution

It introduces a hybrid molecular COM system capable of realizing MIR phonon lasers with remarkably low threshold power despite modest optical quality factors.

Findings

Achieves an ultra-low threshold power of 17.5 nW for the phonon laser.

Demonstrates tunability of mechanical gain and threshold power via cavity mirror distance.

Establishes a link between molecular COM and MIR phonon laser technology.

Abstract

Molecular cavity optomechanics (COM) leverages ultrastrong interactions between confined optical fields and high-frequency molecular vibration, providing a unique platform for exploring high-frequency phonon dynamics. In this work, we theoretically propose the use of a hybrid molecular COM system for realizing an ultra-low-threshold mid-infrared (MIR) phonon laser. Despite an optical quality factor of only $Q_a=100$, an ultra-low threshold power of $\mathrm{P}_{\mathrm{th}} = 17.5~\mathrm{nW}$ is achieved, enabled by giant single-photon optomechanical coupling and molecular collective effect. Moreover, the mechanical gain and threshold power can be further tuned by adjusting the distance between mirrors of the Fabry-P\'{e}rot cavity. Our findings establish the first direct connection between molecular COM and MIR phonon lasers, with potential applications in MIR acoustics and biomedical imaging.