London, May 14 : Your dream of having a Harry Potter 'invisibility cloak' could soon turn into a reality, thanks to physicists at the University of California at Berkeley, US, who have reported the development of the first 3D material able to bend light in the opposite direction to natural materials.
Researchers have long been working out to make it possible to bend, or refract, light in the opposite direction to any natural materials
These meta-materials can now make it possible to create invisibility cloaks a reality.
Jason Valentine, a graduate student in the nano-engineering lab at the University of California at Berkeley, US claims to have developed a 3D material that is capable enough to bend light in the opposite direction to natural materials.
The refractive index is a measure of how the material bends light. Natural materials always have positive refractive indexes while metamaterials have negative refractive indexes.
The newly created material also has negative refractive indexes.
This could be achieved with tiny periodic structures that interact with the electric and magnetic fields that comprise light.
For further investigation, Valentine built a "prism" of 21 alternating layers of silver and magnesium fluoride, organised in a "fishnet" structure
He claims that the refractive index is negative in a small region of the near-infrared spectrum and based his figures on measuring that light was bent backwards by the prism.
However, Gunnar Dolling of the University of Karlsruhe, Germany does not agree with the claims made by Valentine.
In another study, Dolling also made a flat negative refractive-index material for light on the boundary between red and infrared light.
Dolling and his team discovered that the complex interactions between light waves and such metal-based metamaterials can repel a light beam the "wrong way" without a negative refractive index.
"You can only measure a negative refractive index by measuring the phase velocity, meaning the actual speed of light in the medium," New Scientist quoted Dolling, as saying.
The study paper on negative prism was presented on 8 May at the Quantum Electronics and Laser Science Conference in San Jose, California, US.