Self-Injection Locking for Low Phase Noise Phonon Laser

Abstract

Phonon lasers, as analogues of optical lasers, have received widespread attention in optomechanical systems. In this Article, we achieve phonon laser self-injection locking using a microwave photonic architecture with a feedback loop, which can be analyzed as an optoelectronic cavity. The line width of the phonon laser with mechanical frequency of 4.97 GHz is narrowed from 3 kHz to 150 Hz at room temperature. The phase noise of the phonon laser can be as low as −95 dBc/Hz at a frequency offset of 10 kHz, representing a decrease of 40 dB compared to the free-running state. Additionally, we lock two phonon lasers onto different cavity modes within the same fiber loop, achieving a parallel output of the phonon lasers. This research yields promising results in the development of a low-noise oscillator, a coherent phonon laser, and mode-locked phonon lasers in optomechanical arrays.