High-speed waveguide-coupled graphene-on-graphene optical modulators

TL;DR

This paper proposes a high-speed electro-absorption optical modulator using dual graphene layers on a silicon waveguide, achieving over 100 GHz bandwidths at infrared wavelengths, with detailed analysis of material effects.

Contribution

It introduces a novel dual-graphene layer modulator design with realistic performance predictions and analysis of doping and fluctuations impact.

Findings

Over 100 GHz bandwidth at 1.55 μm wavelength

Modulation depth and bandwidth affected by doping levels

Quantitative analysis of background doping effects

Abstract

An electro-absorption optical modulator concept based upon a dual-graphene layer is presented. The device consists of a silicon-on-insulator waveguide upon which two graphene layers reside, separated by a thin insulating region. The lower graphene acts as a tunable absorber, while the upper layer functions as a transparent gate electrode. Calculations based upon realistic graphene material properties show that 3-dB bandwidths over 100 GHz (30 GHz) are possible at near- (\lambda=1.55 \mu m) and mid- (\lambda=3.5\mu m) infrared bands. The effect of background doping and potential fluctuations on the bandwidth, modulation depth and insertion loss are also quantified.