We present the design of an invisible metamaterial fibre operating at optical frequencies, which could be fabricated by adapting existing fibre drawing techniques. The invisibility is realised by matching the refractive index of the metamaterial fibre with the surroundings. We present a general recipe for the fabrication of such fibres, and numerically characterise a specific example using hexagonally arranged silver nanowires in a silica background. We find that invisibility is highly sensitive to details of the metamaterial boundary, a problem that is likely to affect most invisibility and cloaking schemes.
New Scientist reports that the researchers have used a computer model to design an invisible version of their thread. To achieve that, the thread must be just 1 micrometre thick – the metamaterial absorbs some light and so would appear dark if it was any thicker. Their calculations suggest that the thread would be invisible if seen from the side – rather than end on – in polarised light. Fortunately for worried emperors, the model shows that, like other optical metamaterials, the fibre’s optical properties depend strongly on wavelength. An emperor might wear threads that make him appear naked in red light, says Tuniz, but “if you shine green light at him, you see the threads completely”