Hybrid Bound States in Continuum for Enhanced Sensing and Light Manipulation

TL;DR

This paper introduces hybrid bound states in continuum (BICs) that significantly enhance optical sensing and light manipulation by increasing the figure of merit through a novel hybridization approach, supported by theoretical and experimental evidence.

Contribution

It demonstrates that hybrid BICs can surpass traditional limits by increasing the figure of merit, combining high Q and sensitivity, with a proposed waveguide design and initial experimental validation.

Findings

Hybrid BICs outperform dielectric and plasmonic BICs in FOM*.

Symmetric waveguide design enables topologically protected hybrid BICs.

First experimental evidence confirms the existence of hybrid BICs.

Abstract

Light can be influenced by permittivity changes in optical resonators, enabling optical sensors, modulators and optical switches. It is straightforward that a high relative change of intensity per change of permittivity, labelled as figure of merit FOM*, is sought. This FOM* is proportional to the product of quality factor Q and sensitivity S of the resonator. In known resonators, an increase of Q is always accompanied by a decrease of S leaving FOM* constant. Hybridization of resonators has always been reported to lead to an averaging of their performance, only. Here, we theoretically show that light diffracted by bound states in continuum (BICs) breaks that rule. Its FOM* is strongly increased by hybridization, thus outperforming both purely dielectric or plasmonic BICs. We suggest a symmetric waveguide geometry for realising topologically protected hybrid BICs, develop a polymer based fabrication technology and show first experimental evidence of hybrid BICs.