Pulsed and CW Gaussian beam interactions with double negative metamaterial slabs

Richard W. Ziolkowski

doi:10.1364/oe.11.000662

Abstract

The interactions of pulsed and continuous wave (CW) Gaussian beams with double negative (DNG) metatmaterials are considered. Subwavelength focusing of a diverging, normally incident pulsed Gaussian beam with a planar DNG slab is demonstrated. The negative angle of refraction behavior associated with the negative index of refraction exhibited by DNG metamaterials is demonstrated. The transmitted beam resulting from both 3- cycle and CW Gaussian beams that are obliquely incident on a DNG slab are shown to have this property. Gaussian beams that undergo total internal reflection from a DNG metamaterial slab are also shown to experience a negative Goos-Hänchen (lateral) shift. Several potential applications for these effects in the microwave and optical regimes are discussed.

Highlights

A material will be denoted throughout as a double positive (DPS) medium if its relative permittivity εr = ε / ε0 > 0 and permeability μr = μ / μ0 > 0 are both positive
The finite difference time domain (FDTD) simulator does not know which way the wave should refract at a DPS-double negative (DNG) interface nor whether it should focus a beam in a DNG region or cause it to diverge
The oblique incidence set of cases considered dealt with the primary issue of whether a DNG medium will provide a negative angle of refraction or not

Summary

Introduction

The presence of the negative angle of refraction is clearly demonstrated Both ultrafast pulsed (3-cycle) and continuous wave (CW) Gaussian beams are considered. The center frequency of interest to define the index of refraction was chosen to be f0 = 30 GHz , corresponding to a free-space wavelength λ0 = 1.0 cm This value was selected to connect these results to those presented in [8]. The FDTD simulator does not know which way the wave should refract at a DPS-DNG interface nor whether it should focus a beam in a DNG region or cause it to diverge. It calculates what is specified by Maxwell’s equations there. It provides an excellent approach to studying the wave physics associated with DNG metamaterials

Normal incidence results

Oblique incidence results

Goos-Hänchen effect

Findings

Conclusions