A new mechanism for negative refraction and focusing using selective diffraction from surface corrugation

TL;DR

This paper introduces a novel negative refraction mechanism via surface corrugation, demonstrated with experiments on visible light and microwaves, enabling new optical devices like grating lenses.

Contribution

It presents a new surface engineering approach to achieve negative refraction using surface diffraction, independent of bulk material properties.

Findings

Successful demonstration of negative refraction with surface corrugation.

Creation of a grating lens that focuses microwaves.

Surface periodicity controls beam propagation.

Abstract

Refraction at a smooth interface is accompanied by momentum transfer normal to the interface. We show that corrugating an initially smooth, totally reflecting, non-metallic interface provides a momentum kick parallel to the surface, which can be used to refract light negatively or positively. This new mechanism of negative refraction is demonstrated by visible light and microwave experiments on grisms (grating-prisms). Single-beam all-angle-negative-refraction is achieved by incorporating a surface grating on a flat multilayered material. This negative refraction mechanism is used to create a new optical device, a grating lens. A plano-concave grating lens is demonstrated to focus plane microwaves to a point image. These results show that customized surface engineering can be used to achieve negative refraction even though the bulk material has positive refractive index. The surface periodicity provides a tunable parameter to control beam propagation leading to novel optical and microwave devices.