Optically and Electrically Tunable Dirac Points and Zitterbewegung in Graphene-Based Photonic Superlattices

TL;DR

This paper presents a method to control photonic Dirac points in graphene-based superlattices using electrical and optical tuning, enabling deep-subwavelength beam manipulation and exploring Zitterbewegung effects.

Contribution

It introduces a novel platform for tunable photonic Dirac points in graphene superlattices with robust zero-permittivity properties and demonstrates significant spectral tunability.

Findings

Spectral variation of Dirac points exceeds 30 nm in mid-IR and THz frequencies.

Zero-ε Dirac points are highly robust against structural disorder.

Electrical and optical tuning enables deep-subwavelength control of photonic beams.

Abstract

We demonstrate that graphene-based photonic superlattices provide a versatile platform for electrical and all-optical control of photonic beams with deep-subwavelength accuracy. Specifically, by inserting graphene sheets into periodic metallo-dielectric structures one can design optical superlattices that posses photonic Dirac points (DPs) at frequencies at which the spatial average of the permittivity of the superlattice, $\bar{ \varepsilon}$, vanishes. Similar to the well-known zero-$\bar{n}$ bandgaps, we show that these zero-$\bar{\varepsilon}$ DPs are highly robust against structural disorder. We also show that, by tuning the graphene permittivity via the optical Kerr effect or electrical doping, one can induce a spectral variation of the DP exceeding \SI{30}{\nano\meter}, at mid-IR and THz frequencies. The implications of this wide tunability for the photonic Zitterbewegung effect in a vicinity of the DP are explored too.