Gain-tunable optomechanical cooling in a laser cavity

TL;DR

This paper investigates how an optical gain medium within a laser cavity can be used to tune and enhance the cooling of a mechanical resonator, revealing new control mechanisms for optomechanical systems.

Contribution

It introduces a method to control optomechanical damping and cooling via incoherent pumping in a laser cavity with an optical gain medium, enabling transition between coupling regimes.

Findings

Optical damping rate is negligible above laser threshold without external drive.

External coherent drive significantly enhances damping rate.

Incoherent pump strength tunes damping and phonon number, enabling regime transition.

Abstract

We study the optical cooling of the resonator mirror in a cavity-optomechanical system that contains an optical gain medium. We find that the optical damping rate is vanishingly small for an incoherently pumped laser above threshold. In the presence of an external coherent drive however, the optical damping rate can be enhanced substantially with respect to that of a passive cavity. We show that the strength of the incoherent pump provides a conduit to tune the damping rate and the minimum attainable phonon number with the same radiation pressure force, and the latter can be lowered from that of a passive cavity if the thermal contribution is nonnegligible. We also show that the system can undergo a transition from the weak optomechanical coupling regime to the strong optomechanical coupling regime as the incoherent pump strength is varied.