On-chip electrical excitation of micromembrane for fully integrated high-frequency, multi-mode optomechanical resonator

A micromembrane mechanical resonator was fabricated from stoichiometric silicon nitride. Its resonant motion was actuated using an electrical field gradient force generated by electrodes adjacent to the oscillating structure, eliminating the need for electrodes directly on the movable membrane, thereby preserving a high-quality factor. This method enables investigation of multiple modes of the micromembrane, up to the 32^nd mode with a resonant frequency of 78 MHz, using optical measurement technique. The absence of a substrate beneath the membrane makes the structure compatible with optical cavities. This compatibility is crucial for cavity-optomechanical systems, which require integration of mechanical devices with high-finesse optical cavities. Furthermore, by applying phase-shifted RF signals, symmetric modes at the similar resonant frequency can be separated and analyzed. The high-frequency and multi-mode operation, coupled with the substrate-free design makes this micromembrane resonator a promising candidate for applications in optical signal processing, optical component integration with high-finesse cavities, and exploration of cavity optomechanics.