Metamaterials step into the light
April 27, 2012 | Source: IEEE Spectrum
Scientists in England and Valencia, Spain, have constructed what may be the first practical metamaterial that manipulates visible light.
The researchers predict it could be used for subpicosecond (less than a trillionth of a second) optical switches and finely controlled laser pulses. The layered structure, in contrast to the makeup of earlier visible-light devices, means it can conceivably be built up into a usable, full-size object.
However, not everyone is convinced this is possible.
The researchers laid down alternating 15- to 35-nanometer-thick layers of silver and hydrogen silsesquioxane (a type of glass). They then etched rectangular holes through the layers with a focused ion beam to make a structure that looks something like a fishnet.
This “nanofishnet” structure has become a standard arrangement in metamaterials, with each hole acting as an artificial atom. But Garcia-Meca says his group’s nanofishnet has two unprecedented features: its multilayer composition and its use of second-order magnetic resonance to create negative magnetic permeability for red and near-infrared light.
The group was able to adjust the material’s index of refraction for different wavelengths of lighjt simply by varying the size of the holes in the fishnet.
Ref.: C. García-Meca et al., Low-Loss Multilayered Metamaterial Exhibiting a Negative Index of Refraction at Visible Wavelengths, Physical Review Letters, 2011, [DOI: 10.1103/PhysRevLett.106.067402]
Ref.: Costas M. Soukoulis and Martin Wegener, Past achievements and future challenges in the development of three-dimensional photonic metamaterials, Nature Photonics, 2011 [DOI: 10.1038/nphoton.2011.154]
Ref.: Costas M. Soukoulis and Martin Wegener, Past Achievements and Future Challenges in 3D Photonic Metamaterials, arxiv:1109.0084