A chip-scale oscillation-mode optomechanical inertial sensor near the thermodynamical limits

TL;DR

This paper presents a chip-scale optomechanical inertial sensor that achieves near thermodynamical limits of sensitivity, with high precision and stability suitable for various practical applications, using novel radio-frequency optomechanical readout techniques.

Contribution

The work introduces a chip-scale optomechanical inertial sensor with enhanced sensitivity and stability, operating near thermodynamical limits, and demonstrates a new radio-frequency readout method using a photonic crystal cavity.

Findings

Achieves 8.2 micro-g/Hz^1/2 velocity random walk at 100 Hz

Operates 2.56 times above thermodynamical limit at small integration times

Provides 43-dB dynamic range in a room-temperature solid-state device

Abstract

High-precision inertial sensing and gravity sensing are key in navigation, oil exploration, and earthquake prediction. In contrast to prior accelerometers using piezoelectric or electronic capacitance readout techniques, optical readout provides narrow-linewidth high-sensitivity laser detection along with low-noise resonant optomechanical transduction near the thermodynamical limits. Here an optomechanical inertial sensor with 8.2micro-g/Hz^1/2 velocity random walk (VRW) at acquisition rate of 100 Hz and 50.9 micro-g bias instability is demonstrated, suitable for consumer and industrial grade applications, e.g., inertial navigation, inclination sensing, platform stabilization, and/or wearable device motion detection. Driven into optomechanical sustained-oscillation, the slot photonic crystal cavity provides radio-frequency readout of the optically-driven transduction with enhanced 625 microg/Hz sensitivity. Measuring the optomechanically-stiffened oscillation shift, instead of the optical transmission shift, provides a 220x VRW enhancement over pre-oscillation mode detection due to the strong optomechanical transduction. Supported by theory, this inertial sensor operates 2.56x above the thermodynamical limit at small integration times, with 43-dB dynamic range, in a solid-state room-temperature readout architecture.