- Elizabath Philip,
- M. Zeki Güngördü,
- Sharmistha Pal,
- Patrick Kung,
- Seongsin Margaret Kim
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https://link.springer.com/article/10.1007%2Fs10762-017-0405-y
In this article, recent progress and development of terahertz chiral metamaterials including stereometamaterials are thoroughly reviewed. This review mainly focuses on the fundamental principles of design and arrangement of meta-atoms in metamaterials exhibiting chirality with various asymmetry and symmetry and 2D and 3D configuration. Related optical and propagation properties in chiral metamaterials, such as optical activity, circular dichroism, and negative refraction for each different chiral metamaterials, are compared and investigated. Finally, comparison between chiral metamaterials with stereometamaterials in terms of the polarization selective operation along with the similarity and the distinction is addressed as well.
http://www.photonics.com/Article.aspx?AID=57821
TUSCALOOSA, Ala., Oct. 15, 2015 — Manipulating the speed of light more effectively than cold-atom methods, a metamaterial design could find use in optical networks and sensors.
The "slow light" effect was demonstrated using terahertz waves, but could be applied to other wavelengths including visible light, according to researchers at The University of Alabama.
"Slow light will lead to the development of optical buffers and delay lines as essential elements of future ultrafast all-optical communication networks that could meet the ever-increasing demands for long-distance communications," said professor Dr. Seongsin Margaret Kim.
From left, graduate student Mohammad Parvinnezhad Hokmabadi, Dr. Patrick Kung and Dr. Seongsin Margaret Kim work with the terahertz metamaterial. Images courtesy of The University of Alabama.
"In addition, enhanced interaction of photons with matter by lowering the speed of light gives rise to reduced power consumption in nonlinear optical switching devices and ultra-accurate sensing performance of optical sensors."
Light is generally accepted to travel at a constant speed, but its group velocity can be slowed by passing through refractive materials. Compared to its top speed in a vacuum, light travels slightly slower in air, and slightly slower still in water. These changes in speed are fairly insignificant, however.
Metamaterials, on the other hand, can be engineered with nanoscale structures that interact with light to significantly slow or even stop it.
Metamaterials consist of patterns whose size, geometry and orientation can be selected for exotic optical properties.
Unlike the best known methods for slowing light, which involve cold atoms, metamaterials use no energy and are much less complex to implement. They also show promise for use in optical filters, modulators, invisibility cloaks, superlenses and light absorbers.
The Alabama researchers fabricated and characterized a thin, flexible metamaterial film on a silicon substrate that behaves as if it is 1,000 times thicker than its actual thickness. This "effective thickness" had been difficult to gauge previously, the researchers said.
The work was supported by the National Science Foundation and published in Scientific Reports (doi: 10.1038/srep14373 [open access]).
