Feedback-Control Acceleration Sensing: Toward a Practical Small-Scale Levitated Optomechanical Accelerometer

Levitated optomechanical accelerometers (LOMAs) are expected to achieve ultrahigh precision as the optical levitation of the inertial mass will essentially isolate external thermal effects from the mechanical support. However, most designs of the accelerometers currently remain in the proof-of-principle stage in the laboratory. Here a practical accelerometer header in centimeter-scale is presented with the feedback control. An inertial mass of about 10 ng silica sphere is levitated in a dual-beam counter-propagating optical trap. The sensitivity is achieved in air as 232
$\pm 120 ~\mu \text{g}$
/Hz1/2 at 1–10 Hz, and 25.5
$\pm 8.2 ~\mu \text{g}$
/Hz1/2 at about 55 Hz. The bias stability is evaluated as
$418.1 ~\mu \text{g}$
at 0 g input by the Allan variance. At last, acceleration sensing of the header is tested on the city roads, and the output differences from a commercial reference accelerometer are mostly within 21 mg (
$1\sigma $
) in periods of about 480 s. It is the first demonstration of a practical small-scale LOMA, which will be an important step toward further improvement in future.