Trapped-mode excitation in all-dielectric metamaterials with loss and gain

TL;DR

This paper demonstrates that introducing non-Hermitian perturbations with loss and gain in all-dielectric metamaterials enables excitation and quality control of trapped modes without altering unit cell symmetry, advancing nanophotonics applications.

Contribution

It shows that non-Hermitian perturbations can excite and restore high-quality trapped modes in dielectric metamaterials without changing their symmetry.

Findings

Non-Hermitian perturbations excite trapped modes without symmetry change.

Loss and gain can compensate asymmetry effects.

High-quality resonances are achievable in non-Hermitian metamaterials.

Abstract

Non-Hermitian photonics based on combining loss and gain media within a single optical system provides a number of approaches to control and generate the flow of light. In this paper, we show that by introducing non-Hermitian perturbation into the system with loss and gain constituents, the high-quality resonances known as trapped modes can be excited without the need to change the symmetry of the unit cell geometry. To demonstrate this idea, we consider a widely used all-dielectric planar metamaterial whose unit cell consists of a pair of rectangular nanoantennas made of ordinal (with loss) and doped (with gain) silicon. Since the quality factor of the trapped-mode resonance can be controlled by changing both spatial symmetry and non-Hermiticity, varying loss and gain allows us to compensate for the influence of asymmetry and restore the quality factor of the localized mode. The results obtained suggest new ways to achieve high-quality resonances in non-Hermitian metamaterials promising for many practical applications in nanophotonics.