Metamaterial gradient index lens

Abstract

Examples of the present invention include a gradient index element formed from a material such as a metamaterial, the material having an index profile and an index gradient profile, where the index profile includes at least one discontinuity and the index gradient profile is substantially continuous.

Description

FIELD OF THE INVENTION[0001]The invention relates to gradient index materials, such as gradient index metamaterials, and applications thereof.BACKGROUND OF THE INVENTION[0002]Metamaterials are typically artificially structured composite materials. Components and structural parameters may be selected to obtain electromagnetic properties that are not readily available in a homogeneous material.[0003]The electromagnetic response of metamaterials is discussed in Int. Pub. WO 2006 / 023195 to Smith et al. In some metamaterial examples, permittivity and / or permeability may be negative at the electromagnetic frequency of interest. A metamaterial typically comprises a plurality of unit cells. In typical examples, each unit cell includes an electrically conducting pattern, such as a resonator, for example a split ring resonator, supported on a dielectric substrate. The metamaterial response may be determined from the unit cell parameters. Unit cell parameters include parameters such as resonan...

AI Technical Summary

Benefits of technology

[0007]Examples are not restricted to metamaterials. However, the artificial structure of the metamaterial facilitates the provision of carefully tailored index discontinuities and controlled index profiles, and embodiments of the present invention include gradient index metamaterial lenses having improved properties. The use of metamaterials allows the spatial index profile to be controlled at the scale of the unit cell. Typically, unit cell dimensions are somewhat less than the wavelength of electromagnetic radiation of interest, for example less than approximately ⅕ the operational wavelength. Applications include improved radio frequency (RF) devices, including lenses and beam steering devices, in particular automotive radar application, but are not limited to such devices.

Problems solved by technology

However, the range of unit cell parameters available may have an effective upper and lower bound, for example due to manufacturing limitations such as physical limits on a size variation.

Such limitations conventionally present a restriction on the index variation possible within a metamaterial, and limit applications of a metamaterial.

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