A microchip optomechanical accelerometer

TL;DR

This paper presents an integrated chip-scale optomechanical accelerometer with high sensitivity, broadband operation, and the potential for advanced motional sensing, achieved through a novel nano-tethered test mass and optical readout.

Contribution

The authors demonstrate a fully integrated, chip-scale optomechanical accelerometer with high resolution and bandwidth, enabling new possibilities for on-chip inertial sensing.

Findings

Achieved broadband acceleration resolution of 10 μg/rt-Hz.

Bandwidth greater than 20 kHz.

Dynamic range of 50 dB with low optical power.

Abstract

The monitoring of accelerations is essential for a variety of applications ranging from inertial navigation to consumer electronics. The basic operation principle of an accelerometer is to measure the displacement of a flexibly mounted test mass; sensitive displacement measurement can be realized using capacitive, piezo-electric, tunnel-current, or optical methods. While optical readout provides superior displacement resolution and resilience to electromagnetic interference, current optical accelerometers either do not allow for chip-scale integration or require bulky test masses. Here we demonstrate an optomechanical accelerometer that employs ultra-sensitive all-optical displacement read-out using a planar photonic crystal cavity monolithically integrated with a nano-tethered test mass of high mechanical Q-factor. This device architecture allows for full on-chip integration and achieves a broadband acceleration resolution of 10 \mu g/rt-Hz, a bandwidth greater than 20 kHz, and a dynamic range of 50 dB with sub-milliwatt optical power requirements. Moreover, the nano-gram test masses used here allow for optomechanical back-action in the form of cooling or the optical spring effect, setting the stage for a new class of motional sensors.