Cavity optomechanical resonators have exhibited ultrahigh displacement sensitivity close to the quantum limit and hold promise for technological advances in metrology and quantum information processing. Building cavity optomechanics on chip allows for scalability afforded by CMOS-compatible fabrication and integration with well-established microwave and microelectromechanical system (MEMS) technologies. Chip-scale optomechanics ideally requires a material with a combination of desirable properties, including wide transparency window, low mechanical damping, low optical loss and capability of carrying out active functions such as wavelength conversion. In this talk, I will present our research on the development of noncentrosymmetric crystalline materials, particularly piezoelectric aluminum nitride (AlN), for building integrated optomechanical resonators and nonlinear optical components. Using low-loss AlN strip nanophotonic waveguides and microring resonators, we obtain efficient second harmonic generation and high-speed electro-optic modulation. AlN resonator’s piezoelectricity and high optical Q-factor enable a new class of “piezo-opto-mechanical” system vibrating at X-band frequencies. Our embedment of piezoelectric materials in nanophotonic circuits is applicable for metrology applications requiring ultrasensitivity and may provide a pathway to on-chip entangled photon pair source and fully integrated quantum optical circuits.
