Beam Propagation in Photonic Crystals

TL;DR

This paper provides a detailed theoretical and numerical analysis of beam propagation in 1D and 2D photonic crystals, revealing that the propagation direction can differ from the normal to the dispersion curve due to evanescent waves.

Contribution

It introduces a renormalized dispersion curve that accurately predicts beam propagation directions in photonic crystals, challenging previous assumptions.

Findings

Propagation direction can differ from the normal to the dispersion curve.

Evanescent waves influence beam propagation.

A renormalized dispersion curve improves prediction accuracy.

Abstract

The recent interest in the imaging possibilities of photonic crystals (superlensing, superprism, optical mirages etc...) call for a detailed analysis of beam propagation inside a finite periodic structure. In this paper, we give such a theoretical and numerical analysis of beam propagation in 1D and 2D photonic crystals. We show that, contrarily to common knowledge, it is not always true that the direction of propagation of a beam is given by the normal to the dispersion curve. We explain this phenomenon in terms of evanescent waves and we construct a renormalized dispersion curve that gives the correct direction.