[1] The properties stem from the unique structure of the metal-dielectric composites, with features smaller than the wavelength of light separated by subwavelength distances.
[3] Various research groups are experimenting with different approaches to make plasmonic materials that exhibit lower losses and tunable optical properties.
Also known as left-handed or negative index materials, Veselago theorized that they would exhibit optical properties opposite to those of glass or air.
[7] In 2007, a collaboration between the California Institute of Technology, and the NIST reported narrow band, negative refraction of visible light in two dimensions.
[4][5] To create this response, incident light couples with the undulating, gas-like charges (plasmons) normally on the surface of metals.
This narrow channel serves as a transformative guide that, in effect, traps and compresses the wavelength of incoming light to a fraction of its original value.
Potential fabrication methods include multilayer thin film deposition, focused ion beam milling and self-assembly.
[10][11] The reported hyperbolic devices showed multiple functions for sensing and imaging, e.g., diffraction-free, negative refraction and enhanced plasmon resonance effects, enabled by their unique optical properties.
More recently, researchers used a novel self-folding technique to create a three-dimensional array of split-ring resonators that exhibits isotropy when rotated in any direction up to an incident angle of 40 degrees.
By arranging the strips at different angles to each other, 4-fold symmetry was achieved, which allowed the resonators to produce effects in multiple directions.
By incorporating this metamaterial into integrated optics on an IC chip, negative refraction was demonstrated over blue and green frequencies.
[18] Potential applications of graphene plasmonics involve terahertz to midinfrared frequencies, in devices such as optical modulators, photodetectors and biosensors.
The material is compatible with existing CMOS technology (unlike traditional gold and silver), mechanically strong and thermally stable at higher temperatures.
[21] Possible applications include a "planar hyperlens" that could make optical microscopes able to see objects as small as DNA, advanced sensors, more efficient solar collectors, nano-resonators, quantum computing and diffraction free focusing and imaging.
A theorized superlens could exceed the diffraction limit that prevents standard (positive-index) lenses from resolving objects smaller than one-half of the wavelength of visible light.
Structures are optimized using finite difference time domain electromagnetic simulations, fabricated using a combination of electron beam lithography and electroplating, and tested using both near-field and far-field optical microscopy and spectroscopy.