Harry Potter-like invisibility cloak in the offing

In a first, scientists have developed an invisibility cloaking technique based on the manipulation of the frequency of light waves as they pass through an object, a breakthrough that could make 3D objects invisible from all directions.

The new device, developed by researchers from the US-based 'The Optical Society', a scientific society dedicated to advancing the study of light, is known as spectral invisibility cloak.

The device can completely hide arbitrary objects under broadband illumination (with light sources containing many colours), unlike the cloaking devices currently in use, which can conceal the object of interest only when the object is illuminated with just one colour of light, researchers said.

The study, published in the journal Optica, could be constructive for sensing, telecommunications and information processing technologies.

It could be further extended to make 3-D objects invisible from all the directions.

"Our work represents a breakthrough in the quest for invisibility cloaking," said Jose Azana, one of the researchers in the team.

"We have made a target object fully invisible to observation under realistic broadband illumination by propagating the illumination wave through the object with no detectable distortion, exactly as if the object and cloak were not present," Azana said.

While the new design would need further development before it could be translated into a Harry Potter-style wearable invisibility cloak, the demonstrated spectral cloaking device could be useful for a range of security goals.

"Conventional cloaking solutions rely on altering the propagation path of the illumination around the object to be concealed; this way, different colours take different amounts of time to traverse the cloak, resulting in easily detectable distortion that gives away the presence of the cloak," said another researcher Luis Romero Cortes.

"Our proposed solution avoids this problem by allowing the wave to propagate through the target object, rather than around it, while still avoiding any interaction between the wave and the object," he added.

The team is also working to advance practical applications for single-direction spectral cloaking in one-dimensional wave systems, such as for fibre optics-based applications.