Ultrathin Ultra-broadband Electro-Absorption Modulator based on Few-layer Graphene based Anisotropic Metamaterial

TL;DR

This paper proposes a nanoscale, ultra-broadband electro-absorption modulator using few-layer graphene in a dielectric metamaterial, achieving high modulation depth, polarization independence, and low insertion loss for infrared applications.

Contribution

It introduces a novel multilayer graphene dielectric stack design that outperforms mono-layer graphene devices in broadband electro-absorption modulation.

Findings

High modulation depth achieved

Ultra-broadband performance demonstrated

Low insertion loss due to metamaterial properties

Abstract

In this article, a few-layered graphene-dielectric multilayer (metamaterial) electro-optic modulator has been proposed in the mid and far infrared range that works on electro-absorption mechanism. Graphene, both mono layer and few layer, is an actively tunable optical material that allows control of inter-band and intra-band transition by tuning its chemical potential. Utilizing this unique feature of graphene, we propose a multilayer graphene dielectric stack where few layer graphene is preferred over mono layer graphene. Although the total thickness of the stack still remains in the nanometer range, this device can exhibit superior performances in terms of (i) high modulation depth, (ii) ultra-broadband performance, (iii) ultra-low insertion loss due to inherent metamaterial properties, (iv) nanoscale footprint, (v) polarization independence and (vi) capability of being integrated to a silicon waveguide. Interestingly, these superior performances, achievable by using few layer graphene with carefully designed metamaterial, may not be possible with mono layer graphene. Our proposals have been validated by both the effective medium theory and general transfer matrix method.