Metamaterial-induced-transparency engineering through quasi-bound states in the continuum by using dielectric cross-shaped trimers

TL;DR

This paper introduces a method to engineer narrowband transparency in dielectric metasurfaces using quasi-bound states in the continuum, enabling polarization-dependent sensing applications.

Contribution

It demonstrates the control of resonance overlap in all-dielectric metasurfaces via a silicon trimer with broken symmetry, advancing transparency engineering techniques.

Findings

Resonance overlap governed by a silicon trimer with broken symmetry.

Main contributions from magnetic dipole and electric quadrupole multipoles.

Potential for polarization-dependent sensing and biosensing applications.

Abstract

This study presents a novel approach to activate a narrowband transparency line within a reflecting broadband window in all-dielectric metasurfaces, in analogy to the electromagnetically-induced transparency effect, by means of a quasi-bound state in the continuum (qBIC). We demonstrate that the resonance overlapping of a bright mode and a qBIC-based nearly-dark mode with distinct Q-factor can be fully governed by a silicon trimer-based unit cell with broken-inversion-symmetry cross shape, thus providing the required response under normal incidence of a linearly-polarized light. Our analysis that is derived from the far-field multipolar decomposition and near-field electromagnetic distributions uncovers the main contributions of different multipoles on the qBIC resonance, with governing magnetic dipole and electric quadrupole terms supplied by distinct parts of the dielectric ``molecule.'' The findings extracted from this research open up new avenues for the development of polarization-dependent technologies, with particular interest in its capabilities for sensing and biosensing.