Orientation dependence of the optical spectra in graphene at high frequencies

TL;DR

This paper investigates how the optical spectra of graphene depend on orientation at high frequencies, revealing significant anisotropy in conductivity related to polarization direction, with potential applications as a high-frequency polarizer.

Contribution

It provides a detailed analysis of the orientation-dependent optical conductivity of graphene at high frequencies using the Kubo formula, highlighting anisotropic effects and potential device applications.

Findings

Optical conductivity anisotropy increases at high frequencies.

Photon absorption varies significantly with polarization direction.

Potential use as a high-frequency partial polarizer.

Abstract

On the basis of the Kubo formula we evaluated the optical conductivity of a graphene sheet. The full behavior of frequency as well as temperature dependence of the optical conductivity is presented. We show that the anisotropy of conductivity can be significantly enhanced at high frequencies. The photon absorption depends on the field polarization direction. At the frequency comparable to the maximum separation of upper and lower bands the photon-induced conduction of electrons is strongly suppressed if the polarization of field is along the zigzag direction. The corresponding optical conductivity is several orders of magnitude weaker than that when the light is polarizing along the armchair direction. We propose that the property of orientation selection of absorption in the graphene can be used as a basis for a high-frequency partial polarizer.