Unusual reflection of electromagnetic radiation from a stack of graphene layers at oblique incidence

TL;DR

This paper investigates how electromagnetic waves interact with single and multiple graphene layers at various angles, revealing polarization-dependent behaviors and the potential for tunable, spectral-selective mirrors and polarizers.

Contribution

It introduces the concept of using graphene stacks as tunable photonic structures with polarization control and spectral filtering capabilities.

Findings

Graphene's absorbance varies with polarization and incidence angle.

Stacked graphene enhances polarization-dependent effects.

Periodic graphene stacks act as tunable photonic crystals.

Abstract

We study the interaction of electromagnetic (EM) radiation with single-layer graphene and a stack of parallel graphene sheets at arbitrary angles of incidence. It is found that the behavior is qualitatively different for transverse magnetic (or p-polarized) and transverse electric (or s-polarized) waves. In particular, the absorbance of single-layer graphene attains minimum (maximum) for p (s) polarization, at the angle of total internal reflection when the light comes from a medium with a higher dielectric constant. In the case of equal dielectric constants of the media above and beneath graphene, for grazing incidence graphene is almost 100% transparent to p-polarized waves and acts as a tunable mirror for the s-polarization. These effects are enhanced for the stack of graphene sheets, so the system can work as a broad band polarizer. It is shown further that a periodic stack of graphene layers has the properties of an one-dimensional photonic crystal, with gaps (or stop--bands) at certain frequencies. When an incident EM wave is reflected from this photonic crystal, the tunability of the graphene conductivity renders the possibility of controlling the gaps, and the structure can operate as a tunable spectral--selective mirror.