In the classic desert-highway mirage, hot air above the road bends light from the sky towards the eye, making the road look like the sky. The same effect can be created with transparent sheets of carbon nanotubes, say Ali Aliev and his colleagues at the University of Texas at Dallas.
When current is applied, the sheets' high electrical conductance and porosity allow them to quickly heat the surrounding liquid or gas, changing the angle at which it bends light. The team shot a laser beam at the sheets, and adjusted the amount of electrical power applied to the nanotube sheets to tune the bending of the beam. They showed that they could switch this 'cloaking' effect on (pictured top) and off (bottom) using a nanotube sheet immersed in water.
The researchers suggest that the sheets could be used as an optical deflector — important in optical scanning and data processing — or even as a form of 'invisibility cloak'.
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A mirage of invisibility. Nature 478, 159 (2011). https://doi.org/10.1038/478159c
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DOI: https://doi.org/10.1038/478159c
