Flat lens imaging does not need negative refraction

TL;DR

This paper argues that flat lens imaging observed in photonic crystal experiments is due to anisotropic scattering, not negative refraction as previously claimed, challenging the interpretation of such phenomena in left-handed materials.

Contribution

It clarifies that flat lens imaging in photonic crystals results from anisotropic scattering, not negative refraction, providing a new understanding of the underlying physics.

Findings

Imaging is caused by anisotropic scattering, not negative refraction.

Negative refraction is not necessary for flat lens imaging in photonic crystals.

The observed focusing can be explained without invoking left-handed materials.

Abstract

In a recent communication, Parimi et al. (Nature 426, 404 (2003)) reported the experimental results on imaging by a flat lens made of photonic crystals. They attributed the observed focusing to the negative refraction expected for the Left-Handed-Materials (LHMs). Here we demonstrate that the experimental observation is irrelevant to the negative refraction of LHMs. Rather, the phenomenon is a natural result of the anisotropic scattering by an array of scatterers.