University of California at San Diego (UCSD) physicists have discovered a new technique for controlling the direction and speed of light with the help of memory metamaterials whose characteristics can be subjected to constant changes.
A metamaterial represents a structure obtained from different substances which when combined together, generate optical properties that do not naturally exist. In this study, the metamaterial used by researchers is a hybrid device built from split ring resonators (SRRs), which are gold rings with a portion removed from one side, placed upon a thin vanadium dioxide (VO2) layer.
When a pulse of electricity was applied to this SRR- VO2 hybrid device, the physicists were able to produce a temperature gradient across the device that selectively alters the manner of interaction of the material with light, for instance, altering the direction and speed of the light, or the amount of light that is absorbed or reflected at every point along the hybrid device. Even when voltage is no longer applied, the material is capable of storing these alterations in memory.
The UCSD researchers collaborated with the researchers from the Electronics and Telecommunications Research Institute (ETRI) in South Korea and the Duke University in Durham, N.C. and used this gradient-generating concept to demonstrate the possibility of modifying the manner of light interaction with the metamaterial on the order of one wavelength for a single terahertz-frequency radiation. The findings were recorded in a paper published by AIP's Applied Physics Letters.
The ability to optimize metamaterial devices to this accuracy level repeatedly,whenever needed and even after the fabrication of the metamaterial paves way for novel methods such as the capability to produce gradient index of refraction (GRIN) devices, that find application in different communication and imaging technologies.
Source: http://www.ucsd.edu/