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Structures with Negative Refractive Index for Applications in Optics and Nanophotonics

Ames Laboratory

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Technology Marketing Summary

Iowa State University and Ames Laboratory researchers have developed materials and structures with a negative refractive index that potentially open new frontiers in optics applications.


No known materials exist in nature with a negative refractive index—natural materials reflect light or electromagnetic radiation. Materials with a negative refractive index (NIMs) have been demonstrated and are currently made through a combination of artificial “electric atoms”—metallic wires with negative electrical permittivity, and artificial “magnetic atoms”—split ring resonators with negative magnetic permeability. These NIMs are typically built from an array of split ring resonators combined with a grid of continuous metal wires. However, these materials are difficult to fabricate and characterize, especially at high (THz and optical) frequencies. To overcome this drawback, ISU and Ames Laboratory researchers have recently developed left-handed materials, also referred to as metamaterials, and structures that have a negative refractive index. These NIMs are constructed using wire-pair structures that lie in parallel planes, making fabrication easier. In addition, the structures have a negative refractive index at microwave and optical frequencies and thus may enable new applications in optics, such as “perfect lenses”, and nanophotonics.


* Amenable to conventional micro-fabrication techniques
* Allows for the complex, multilayer interconnects used integrated circuits to be applied to these wire-pair NIMs
* May enable miniaturization of devices and components, such as antennas and waveguide structures

Applications and Industries

Advanced optics and imaging; nanoelectronics

More Information

Publication: “Magnetic response in metamaterials at 100 THz”, S. Linden, C. Enkirch, M. Wegner, J. Zhou, T. Koschny and C. M. Soukoulis, 2004, Science 306:1351-1353.

Patents and Patent Applications
ID Number
Title and Abstract
Primary Lab
Patent 8,054,146
Structures with negative index of refraction
The invention provides simplified negative index materials (NIMs) using wire-pair structures, 4-gap single ring split-ring resonator (SRR), fishnet structures and overleaf capacitor SRR. In the wire-pair arrangement, a pair of short parallel wires and continuous wires are used. In the 4-gap single-ring SRR, the SRRs are centered on the faces of a cubic unit cell combined with a continuous wire type resonator. Combining both elements creates a frequency band where the metamaterial is transparent with simultaneously negative .di-elect cons. and .mu.. In the fishnet structure, a metallic mesh on both sides of the dielectric spacer is used. The overleaf capacitor SRR changes the gap capacities to small plate capacitors by making the sections of the SRR ring overlap at the gaps separated by a thin dielectric film. This technique is applicable to conventional SRR gaps but it best deploys for the 4-gap single-ring structures.
Ames Laboratory 11/08/2011
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To: Stacy Joiner<>