Cavity optomechanical sensing in the nonlinear saturation limit

TL;DR

This paper demonstrates a method to significantly extend the dynamic range of cavity optomechanical sensors beyond the cavity linewidth limit by operating in the nonlinear saturation regime, without losing sensitivity.

Contribution

The authors experimentally show that operating in the nonlinear saturation regime can increase the dynamic range of microcavity sensors sixfold while maintaining sensitivity.

Findings

Dynamic range increased six times beyond the cavity linewidth.

Nonlinear saturation operation preserves detection sensitivity.

Method applicable to practical microcavity sensor design.

Abstract

Photonic sensors based upon high-quality optical microcavities have found a wide variety of applications ranging from inertial sensing, electro- and magnetometry to chemical and biological sensing. These sensors have a dynamic range limited by the linewidth of the cavity mode transducing the input. This dynamic range not only determines the range of the signal strength that can be detected, but also affects the resilience of the sensor to large deteriorating external perturbations and shocks in a practical environment. Unfortunately, there is a general trade-off between the detection sensitivity and the dynamic range, which undermines the performance of all microcavity-based sensors. Here we propose an approach to extend the dynamic range significantly beyond the cavity linewidth limit, in the nonlinear modulation regime, without degrading the detection sensitivity for weak signals. With a cavity optomechanical system, we experimentally demonstrate a dynamic range six times larger than the cavity linewidth, far beyond the conventional linear region of operation for such a sensor. The approach demonstrated here will help design microcavity-based sensors to achieve high detection sensitivity and a large dynamic range at the same time, a crucial property for their use in a practical environment.