  Electro-optic frequency combs were employed to rapidly interrogate an
optomechanical sensor, demonstrating spectral resolution substantially
exceeding that possible with a mode-locked frequency comb. Frequency combs were
generated using an integrated-circuit-based direct digital synthesizer and
utilized in a self-heterodyne configuration. Unlike approaches based upon laser
locking or sweeping, the present approach allows rapid, parallel measurements
of full optical cavity modes, large dynamic range of sensor displacement, and
acquisition across a wide frequency range between DC and 500 kHz. In addition
to being well suited to measurements of cavity optomechanical sensors, this
optical frequency comb-based approach can be utilized for interrogation in a
wide range of physical and chemical sensors.
