Boundary-Induced Embedded Eigenstate in a Single Resonator for Advanced Sensing

TL;DR

This paper introduces a novel boundary-induced embedded eigenstate in a single subwavelength resonator, enabling high-resolution sensing applications such as detecting salt dissolution and evaporation rates with minimal footprint.

Contribution

It demonstrates the creation of a boundary-induced BIC in a single resonator, offering a compact alternative to large arrays for sensing and other applications.

Findings

Achieved sub-microliter resolution in evaporation rate measurement.

Demonstrated sensing of NaCl dissolution in water.

Validated boundary-induced BICs as a new sensing mechanism.

Abstract

Electromagnetic embedded eigenstates, also known as bound states in the continuum (BICs), hold a great potential for applications in sensing, lasing, enhanced nonlinearities and energy harvesting. However, their demonstrations so far have been limited to large-area periodic arrays of suitably tailored elements, with fundamental restrictions on the overall footprint and performance in presence of inevitable disorder. In this work, we demonstrate a BIC localized in a single subwavelength resonator obtained by suitably tailoring the boundaries around it, enabling a new degree of control for on-demand symmetry breaking. We experimentally demonstrate how boundary-induced BICs open exciting opportunities for sensing by tracing the dissolution of NaCl in water, determining evaporation rates of distilled and saltwater with a resolution of less than 1e-6 L using a tabletop experimental setup.