Nonreciprocal Phonon Laser

Phonon lasing (coherent mechanical amplification) is a key element in phononic engineering. A one\penalty1000-\hskip0ptway phonon laser would be an indispensable tool to explore chiral light\penalty1000-\hskip0ptsound interactions or to drive chiral phonon devices, yet has remained elusive. This study proposes a strategy to achieve such a device, by coupling an optomechanical system to a spinning resonator. Through the optical Sagnac effect, enhancement or suppression of phonon lasing can be achieved by driving the coupled system from one side or the other. This strategy provides a versatile way to operate spinning devices for applications in directional phonon control, sound sensing, and topological acoustics.