Transverse Anderson localization of light near Dirac points of photonic nanostructures

TL;DR

This study compares how disorder affects light localization in layered photonic structures with Dirac points versus Bragg gaps, revealing that Dirac points resist localization even under high disorder levels.

Contribution

It demonstrates that the localization length increases as the Bragg gap narrows, and near the Dirac point, optical modes remain delocalized despite high disorder levels.

Findings

Localization length increases as the Bragg gap decreases.

Optical modes near the Dirac point are resistant to localization.

High disorder does not localize modes at the Dirac point.

Abstract

We perform a comparative study of the Anderson localization of light beams in disordered layered photonic nanostructures that, in the limit of periodic layer distribution, possess either a Dirac point or a Bragg gap in the spectrum of the wavevectors. In particular, we demonstrate that the localization length of the Anderson modes increases when the width of the Bragg gap decreases, such that in the vanishingly small bandgap limit, namely when a Dirac point is formed, even extremely high levels of disorders are unable to localize the optical modes located near the Dirac point. A comparative analysis of the key features of the propagation of Anderson modes formed in the Bragg gap or near the Dirac point is also presented. Our findings could provide valuable guidelines in assessing the influence of structural disorder on the functionality of a broad array of optical nanodevices.