Dynamical Phonon Laser in Coupled Active-Passive Microresonators

TL;DR

This paper models a phonon laser in coupled microresonators, revealing how optical gain and thermal noise influence phonon amplification through a novel linearization approach of nonlinear dynamics.

Contribution

It introduces a new method to analyze phonon laser dynamics without steady-state assumptions, highlighting the role of thermal noise and gain in optimizing phonon lasing.

Findings

Thermal noise can significantly facilitate phonon laser action.

The approach provides explicit conditions for optimal phonon lasing.

Time-dependent stimulated phonon field amplification is demonstrated.

Abstract

Effective transition between the population-inverted optical eigenmodes of two coupled microcavities carrying mechanical oscillation realizes a phonon analogue of optical two-level laser. By providing an approach that linearizes the dynamical equations of weak nonlinear systems without relying on their steady states, we study such phonon laser action as a realistic dynamical process, which exhibits time-dependent stimulated phonon field amplification especially when one of the cavities is added with optical gain medium. The approach we present explicitly gives the conditions for the optimum phonon lasing, and thermal noise is found to be capable of facilitating the phonon laser action significantly.