Radio-frequency optomechanical characterization of a silicon nitride drum

On-chip actuation and readout of mechanical motion is key for characterizing mechanical resonators and exploiting them for new applications. We capacitively couple a silicon nitride membrane to an off-resonant radio-frequency cavity formed by a lumped element circuit. Despite a low cavity quality factor of about 7.4 and off-resonant, room temperature operation, we are able to parametrize several mechanical modes and estimate their optomechanical coupling strengths. This enables fast characterization of a device without requiring a superconducting cavity, thereby eliminating the need for cryogenic cooling. We also observe optomechanically induced transparency and absorption which is crucial for a number of applications including sensitive metrology, ground state cooling of mechanical motion, and slowing of light.