'Teleportation of Light'
Schematics of the Mach-Zehnder interferometer containing zero-index metamaterial on one arm and SEM images of the fabricated device
A team of international researchers including UCL Electronic and Electrical Engineers have produced a material that leaves absolutely no mark on the light travelling through it. Normally, even travelling through vacuum makes light waves acquire a phase change – but not when crossing these specially nano-patterned materials. For the light beam, it’s just as if there was no space crossed on its journey.
This precise control of the optical phase is based on a unique combination of materials with negative and positive indices of refraction. All naturally occurring materials have a positive index of refraction, which is a measure of how light moves differently when it travels through them. By patterning regular materials at a nano-scale, the researchers engineered the light dispersion within them so that for certain wavelengths of light the beam was changed in an opposite fashion – bending to the left instead of the right, and oscillating backwards instead of forwards. By matching layers of negative and positive index materials so that their effects cancelled out, they could produce zero phase change.
The multidisciplinary group - from Columbia University, University College London, Brookhaven National Laboratory (USA) and the Institute of Microelectronics of Singapore - have designed and built these silicon-based photonic metamaterials in order to demonstrate how the index of refraction of optical materials can be engineered, and to fully control light dispersion.
“We are excited about this breakthrough as it represents the first successful attempt to bring these zero-index metamaterials to the realm of practical applications”, said Dr Panoiu, the researcher who led the work of the UCL group. “This opens up new doors for research in chip-scale integrated devices made of silicon, including transmission lines, optical filters, broadband mirrors and optical isolators.”
This research was supported by grants from the National Science Foundation (NSF), the Defense Advanced Research Projects Agency (DARPA) and the Engineering and Physical Sciences Research Council (EPSRC).
Paper Reference: Nature Photonics