Demonstration of mode splitting in an optical microcavity in aqueous environment

TL;DR

This paper demonstrates mode splitting in an optical microcavity within water, showing potential for sensitive detection of nanoparticles and biomolecules through spectral analysis.

Contribution

It presents the first observation of mode splitting in aqueous environments, enabling advanced resonator sensors for biological and nanoparticle detection.

Findings

Mode splitting observed in water microcavities.

Detection of 50nm polystyrene nanoparticles at low concentrations.

Splitting rate correlates with particle concentration.

Abstract

Scatterer induced modal coupling and the consequent mode splitting in a whispering gallery mode resonator is demonstrated in aqueous environment. The rate of change in splitting as particles enter the resonator mode volume strongly depends on the concentration of particle solution: The higher is the concentration, the higher is the rate of change. Polystyrene nanoparticles of radius 50nm with concentration as low as 5x10^(-6)wt% have been detected using the mode splitting spectra. Observation of mode splitting in water paves the way for constructing advanced resonator based sensors for measuring nanoparticles and biomolecules in various environments.