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  • Metasurface Lens Could Transform Antennas

Photonics.com
Apr 2014
NANJING, China, April 16, 2014 — Traditional antennas could be in for a makeover following a discovery in broadband optics.

Researchers from Southeast University have developed an artificial surface lens that can bend and focus electromagnetic waves. Said to be the first broadband transformation optics metasurface lens, it may lead to the creation of new types of antennas that are ultra-low-profile, flat and could conform to curved surfaces.


A prototype metasurface lens, with simulated X components of electric fields. The source is shown at the bottom left, right and center. Courtesy of Southeast University.


To create the new lens, the researchers deposited an array of inhomogeneous, metallic, U-shaped structures onto a dielectric material. This provided the required surface refractive indexes. The metasurface lens has properties that mimic a Luneburg lens, but maintains a flat shape.

In the study, the lens also demonstrated success in controlling radiated surface waves.

Traditional construction of lenses with such properties is based on geometric optics, and more recent techniques have included holographic optics. This latest discovery complements and expands that, the researchers said.

“We now have three systematical designing methods to manipulate the surface waves with inhomogeneous metasurfaces: the geometric optics, holographic optics and transformation optics," said Tie Jun Cui, a researcher at Southeast University. "These technologies can be combined to exploit more complicated applications."

The research is published in Applied Physics Letters. (doi: 10.1063/1.4870809

For more information, visit: www.seu.edu.cn


GLOSSARY
dielectric
Exhibiting the characteristic of materials that are electrical insulators or in which an electric field can be sustained with a minimum dispersion of power. They exhibit nonlinear properties, such as anisotropy of conductivity or polarization, or saturation phenomena.
luneburg lens
A dielectric sphere with an index of refraction that varies with distance from the sphere center. A parallel beam of rays is focused on the lens surface at a point diametrically opposite the direction of incidence. Energy emanating from a point on the surface is focused into a plane wave.  
geometric optics
A field of physics that deals with light as if it truly were composed of rays diverging in various directions from the source and abruptly bent by refraction or turned by reflection into paths determined by familiar laws. The concept that light travels in a straight line is the basis of geometric optics, which neglects diffraction and acknowledges the wave theory of light only insofar as the wavelengths affect the refractive index.
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