A high-resolution microchip optomechanical accelerometer

Abstract

The monitoring of acceleration is essential for a variety of applications ranging from inertial navigation to consumer electronics. Typical accelerometer operation involves the sensitive displacement measurement of a flexibly mounted test mass, which can be realized using capacitive, piezo-electric, tunnel-current or optical methods. Although optical detection provides superior displacement resolution, resilience to electromagnetic interference and long-range readout, current optical accelerometers either do not allow for chip-scale integration or utilize relatively bulky test mass sensors of low bandwidth. Here, we demonstrate an optomechanical accelerometer that makes use of ultrasensitive displacement readout using a photonic-crystal nanocavity monolithically integrated with a nanotethered test mass of high mechanical Q-factor This device achieves an acceleration resolution of 10 µg Hz^(−1/2) with submilliwatt optical power, bandwidth greater than 20 kHz and a dynamic range of greater than 40 dB. Moreover, the nanogram test masses used here allow for strong optomechanical backaction, setting the stage for a new class of motional sensors.