# Enhancing the speed and sensitivity of a nonlinear optical sensor with noise

## TL;DR

This paper shows how noise can be exploited in nonlinear optical cavities to enhance detection speed and sensitivity for sensing applications, especially in noisy environments.

## Contribution

It introduces a method to turn noise into an advantage for optical sensing using a nonlinear cavity in the bistable regime, optimizing detection speed and sensitivity.

## Key findings

- Detection speed increases with noise strength.
- Sensitivity peaks at an optimal finite noise level.
- Applicable to ultrafast detection in noisy, low-power environments.

## Abstract

We demonstrate how noise can be turned into an advantage for optical sensing using a nonlinear cavity. The cavity is driven by a continuous wave laser into the regime of optical bistability. Due to the influence of fluctuations, the cavity randomly switches between two states. By analyzing residence times in these two states, perturbations to the resonance frequency of the cavity can be detected. Here, such an analysis is presented as a function of the strength of the perturbation and of the noise. By increasing the standard deviation of the noise, we find that the detection speed increases monotonically while the sensitivity peaks at a finite value of the noise strength. Furthermore, we discuss how noise-assisted sensing can be optimized in state-of-the-art experimental platforms, relying solely on the minimum amount of noise present in the cavity due to its dissipation. These results open new perspectives for the ultrafast detection of nanoparticles, contaminants, gases, or other perturbations to the resonance frequency of an optical resonator, at low powers and in noisy environments.