Swept-Frequency Drumhead Optomechanical Resonators

We demonstrate a high-Q (>5 × 106) swept-frequency membrane mechanical resonator achieving resonance tuning over more than one octave via a simple integrated electrical heater. Throughout this tuning range, the membrane displacement noise remains dominated by fundamental thermo-mechanical fluctuations. Such high Q-factor and low displacement noise make the device especially promising for acceleration sensing. The inferred acceleration noise floor of the device is below 1 μg Hz–1/2, an unprecedented level of performances for acceleration sensors operating at frequencies above 50 kHz. The device can also be mechanically stabilized (or driven) via bolometric optomechanics, and we demonstrate laser cooling from room temperature to 10 K using a low finesse optical cavity. This method of frequency tuning is also well-suited to fundamental studies of mechanical dissipation; in particular, we recover the dissipation spectra of many modes, identifying material damping, and coupling to substrate resonances as the dominant loss mechanisms. The device is compatible with established batch fabrication techniques, and its optical readout is compatible with low-coherence light sources (e.g., a monochromatic light-emitting diode).