Spectral cloaking could make objects invisible

Avatar By Le Williams | 2 years ago

Researchers and engineers of the National Institute of Scientific Research (INRS) in Montréal, Canada have successfully fulfilled a new study, offering the first demonstration of invisibility cloaking based on the manipulation of the frequency of light waves as they pass through an object.

“Our work represents a breakthrough in the quest for invisibility cloaking,” said INRS lead researcher José Azaña. “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.”

The approach could be applicable to securing data transmitted over fiber optic lines and also help improve technologies for sensing, telecommunications, and information processing, researchers say.

The new device, called a spectral invisibility cloak, is designed to completely hide arbitrary objects under broadband illumination.

The cloaking device was constructed from two pairs of two commercially available electro-optical components. The first component is a dispersive optical fiber, which forces the different colors of a broadband wave to travel at different speeds. The second is a temporal phase modulator, which modifies the optical frequency of light depending on when the wave passes through the device.

One pair of these components was placed in front of the optical filter while the other pair was placed behind it.

While the researchers demonstrated spectral cloaking when the object was illuminated from only one spatial direction, Azaña said it should be possible to extend the concept to make an object invisible under illumination from every direction.

Additionally, Azaña’s team is working to advance practical applications for single-direction spectral cloaking in one-dimensional wave systems.