Combining techniques that produce light-bending metamaterials and optical fibres, researchers at the University of Sydney have been working on creating real invisible threads.
Alessandro Tuniz is interested in the optical metamaterials that are being fashioned into "invisibility cloaks" in labs across the world.
According to the New Scientist, these metamaterials can control the light waves and have optical properties beyond those of conventional materials.
Tuniz's colleagues Boris Kuhlmey, Simon Fleming and Maryanne Large assembled standard glass rods and metal tubes into a cylinder, heated the assembly until it softened, and drew it into a long thin fibre.
The process preserves the shapes of internal structures, but shrinks them down to tlength, he nanoscale needed to control visible light, and the resultant metamaterial is in the form of a thread that is thin enough to be flexible, like an optical fibre.
Now, the researchers have used a computer model to design an invisible version of their thread, which must be just 1 micrometre thick.
Their calculations suggest that the thread would be invisible if seen from the side - rather than end on - in polarised light. The fibre's optical properties depend strongly on wavelength - there may be threads that are invisible in red light but fully visible in green light.
"The theory is sound," said Asger Mortensen of the Technical University of Denmark in Lyngby and Min Yan of the Royal Institute of Technology in Stockholm, Sweden, who have stretched metamaterials into optical fibres which can transport infrared light.