Electromagnetically induced transparency in hybrid plasmonic-dielectric system

TL;DR

This paper theoretically and numerically investigates a hybrid plasmonic-dielectric system demonstrating electromagnetically-induced transparency (EIT), slow light, and enhanced group index, with potential applications in sensing and optical switching.

Contribution

It introduces a novel hybrid system showing both symmetric and asymmetric EIT effects, with significant group index enhancement due to asymmetry-induced double EIT.

Findings

Symmetric coupling produces a single transparency window.

Asymmetric coupling results in double EIT with improved group index.

The system enables slow light and high transparency efficiency.

Abstract

We present theoretical and numerical analysis of a plasmonic-dielectric hybrid system for symmetric and asymmetric coupling between silver cut-wire pairs and silicon grating waveguide with periodic grooves. The results show that both couplings can induce electromagnetically-induced transparency (EIT) analogous to the quantum optical phenomenon. The transmission spectrum shows a single transparency window for the symmetric coupling. The strong normal phase dispersion in the vicinity of this transparent window results in the slow light effect. However, the transmission spectrum appears an additional transparency window for asymmetry coupling due to the double EIT effect, which stems from an asymmetrically coupled resonance (ACR) between the dark and bright modes. More importantly, the excitation of ACR is further associated with remarkable improvement of the group index from less than 40 to more than 2500 corresponding to a high transparent efficiency by comparing with the symmetry coupling. This scheme provides an alternative way to develop the building blocks of systems for plasmonic sensing, all optical switching and slow light applications.