Extraordinary transmission caused by symmetry breaking

TL;DR

This paper investigates how breaking symmetry in annular aperture arrays enhances terahertz transmission, enabling tunable filtering and sensing through symmetry-induced resonance control.

Contribution

It demonstrates that symmetry breaking allows access to both odd and even resonant modes, significantly improving transmission modulation capabilities.

Findings

Symmetrical AAAs show only odd order resonances.

Asymmetrical AAAs exhibit both odd and even order resonances.

Symmetry breaking achieves up to 99% modulation depth in second order resonance.

Abstract

The terahertz transmission properties of symmetrical and asymmetrical annular apertures arrays (AAAs) are investigated both experimentally and numerically. It is found that only odd order resonant modes are observed for the symmetrical structures but both odd and even order resonances can be shown for the asymmetrical structures. Breaking the symmetry of AAAs by gradually displacing the H-shaped AAAs to U-shaped AAAs allows an intensity modulation depth of 99% of the second order resonance. Simulation results verify the experimental conclusions well. This result provides a tremendous opportunity for terahertz wavelength tunable filtering, sensing, and near-field imaging.