Interaction of acoustic waves with optomechanical resonators and oscillators

摘要

We experimentally study acoustic excitation of a radiation pressure coupled optomechanical resonators above and below self-sustained oscillation threshold. First we demonstrate injection locking of a radiation pressure driven microtoroidal optomechanical oscillator (OMO) via acoustic waves by locking its phase and frequency to a piezoelectric transducer (PZT). We characterize the injection locking process and show that even without proper acoustic impedance matching, the OMO can be locked to the PZT and tuned over 17 kHz with only -30 dBm of RF power driving the PZT. As opposed to the previously reported techniques, injection locking of OMO via acoustic waves does not require optical power modulation or physical contact with the OMO and it can be easily implemented on various platforms to lock different types of OMOs independent of their size and structure. The high efficiency, simplicity and scalability of the proposed approach paves the road toward a new class of photonic systems that rely on synchronization of several OMOs to a single or multiple RF oscillators with applications in optical communication, metrology and sensing. Next we study the acousto-optical response of the same optomechanical resonator below oscillation threshold optical power level. We show that in this regime the reduced damping due to radiation pressure may be used for high sensitivity detection of acoustic waves. We analyze the performance of radiation pressure coupled optomechanical resonators as acousto-optical transducers and explore their potential advantages over other optical and piezoelectric transducers in applications where high sensitivity, low power consumption and small size are critical.