New metamaterial for faster computers, invisibility cloaks

A new metamaterial that refracts light in an unusual way could be used to speed up computers, and even create invisibility cloaks in future, scientists say.
Scientists from the Moscow Institute of Physics and Technology and the Russian Academy of Sciences have proposed a two-dimensional metamaterial composed of silver elements.
In the future, these structures may be used to develop compact optical devices, as well as to create an 'invisibility cloak.'
Computer simulations showed that it would be a high performance material for light with a wavelength from 400-500 nanometres (violet, blue and light blue), researchers said.
A metamaterial has properties which are created by an artificial periodic structure.

When light is incident on the surface of such a material, the refracted light is on the same side of the normal to the surface as the incident light.

The unusual optical effects do not necessarily imply the use of the 3D metamaterials. Light can also be manipulated with the help of two-dimensional structures metasurfaces, researchers said. In fact, it is a thin film composed of individual elements.
The principle of operation of the metasurface is based on the phenomenon of diffraction. Any flat periodic array can be viewed as a diffraction lattice, which splits the incident light into a few rays.

The number and direction of the rays depends on geometrical parameters - the angle of incidence, wavelength and the period of the lattice.
The structure of the unit cell determines how the energy of the incident light is distributed between the rays.
For a negative refractive index it is necessary that all but one of the diffraction rays are suppressed, then all of the incident light will be directed in the required direction.
The unit cell of the proposed lattice is composed of a pair of closely spaced silver cylinders with a radius of the order of 100 nanometres.
Researchers were able to adjust the parameters of the cell so that the resulting optical lattice response is consistent with abnormal refraction of the incident wave.

The results achieved can be applied to control optical signals in ultra-compact devices, optical transmission and information processing technologies, which will help expedite computer processing in the future.
The conventional electrical interconnects used in modern chips are operating at the limit of their carrying capacities and inhibit further growth in computing performance.
To replace the electrical interconnects by optical we need to be able to effectively control optical signals at nanoscale, researchers said.
In order to solve this problem scientists are focused on creating structures capable of 'turning' the light in the desired direction.
The research was published in the journal Optical Material Express.