Polarization-based control of phonon laser action in a Parity Time-symmetric optomechanical system

Realizing a convenient way to control the phonon laser action is of great importance and may find applications in phonon laser devices engineering. Here we propose a vector parity time (PT)-symmetric optomechanical system to study the phonon laser action. We find that there is a specific region for the optimum mechanical gain appearing in parameter areas of the cavity gain and loss. The intensity of phonon laser action can be well controlled by adjusting the polarization of the pump field. The threshold value of phonon laser action manifests as a function relationship of the polarization direction θ. Furthermore, an ultralow threshold (even if threshold less) can be obtained around the exceptional point with the gain–loss balance. Our results indicate that the intensity and threshold of the phonon laser action can be continuously adjusted by only tuning the photon polarization, which provides a new degree of freedom to realize phonon laser regulation.A phonon laser is the mechanical equivalent of an optical laser and has potential application in precise, non-destructive imaging techniques. The authors theoretically demonstrate that the features of a phonon laser can be controlled by the polarization of light.