Nanoscale pixels that can encode two different full-colour images in the same area are presented in Nature Communications this week. This method opens up the possibility of producing 3D images on microscale displays and developing high-density multiplexed optical data storage. In the future, this technology may also lead to the development of ultra-high resolution 3D displays, holograms and advanced elements for anti-counterfeiting and steganography.
Nanostructures are known to respond strongly to specific colours, based on their size and geometry. This property has been exploited to build colour filters already, but these are normally not responsive to different polarisations of light. Joel Yang and colleagues show that by changing the shape of the nanostructures into ellipses or pairs of squares and varying their orientation, it is possible to overlay two full-colour images. These images are then decoded by looking at them with different polarisations of light, much the same as with 3D movies. By encoding two identical images offset slightly from one another, they are also able to produce 3D prints.