Experimental determination and numerical simulation of the properties of negative index of refraction materials

Abstract

Negative index of refraction materials have been postulated for many years but have only recently been realized in practice. In the microwave region these materials are constructed of rings and wires deposited on a dielectric substrate to form a unit cell. We have constructed, experimentally characterized and simulated several of these structures operating in the 10 - 15 GHz range. Our simulations using Maxwell's Equations solvers have included wire arrays, ring arrays and assemblies of unit cells comprised of rings and wires. We find good agreement between the numerical simulations and experimental measurements of the scattering parameters and index of refraction. The procedure was to first model ring and wire structures on the unit cell level to obtain scattering parameters from which effective å, ì and n were retrieved. Next an assembled array of unit cells forming a 12 degrees wedge was used for the Snell's Law determination of the negative index of refraction. For the structure examined the computed value of n is within 20% of the one experimentally measured in the Snell's Law experiment from 13.6 to 14.8 GHz.

Tunable transmission and bistability in left-handed band-gap structures

“…Such materials can also be described by a negative refractive index, as was demonstrated by several reliable experiments [3,4] and numerical finite-difference time-domain simulations [5].…”

A positive future for double-negative metamaterials

“…As such, some of the ideas reviewed in this manuscript are speculative in nature, although they are based on mathematical foundations and are consistent with physical realizability conditions. It is important to point out that currently there are several active research directions in this field, one of which is the research efforts of various groups aimed at the construction and fabrication of 3-D volumetric DNG MTMs by embedding in host media various classes of small inclusions such as wires and split-ring resonators [8], [28]- [34], broadside coupled split-ring resonators [35], capacitively loaded strips and split-ring resonators [13], omega structures [36], [37], and space-filling elements [38] to name a few. Another direction of research effort by several groups is focused on 2-D planar DNG MTMs that utilize circuit and transmission-line implementations.…”

Negative index effects from a homogeneous positive index prism

“…For example, negative permittivity can be achieved by arrays of wires [2], and negative permeability can be achieved by arrays of split ring resonators [3]. These cellular structures have been combined to produce metamaterials with a negative refraction index [4][5][6][7].…”