Metasurfaces will control the colour of your car

The ability to control the appearance of objects at will might actually become a reality in the future. Assistant Professor Søren Raza from DTU Nanotech has just started a new project on Smart Optics where he will work on nanostructures in metasurfaces. The idea is to use electrical current to activate and change metasurfaces thereby making it possible to change the appearance and properties of a surface repeatedly.

Until now, most research has focused on passive metasurfaces. This means that once they have been fabricated, they cannot be changed. Although some advances have been made, very little research has focused on active metasurfaces that can be changed repeatedly.

For the next four years, Søren and his team will be looking into this challenge in this project funded by the Independent Research Fund Denmark. They will investigate how to make the most optimal design for active metasurfaces, which can be controlled and altered after fabrication.

‘Metasurfaces consist of nano-antennae arranged in a very specific pattern. These surfaces are very thin – only around 100 nanometers – which make them obvious candidates for integration into electronic components and small devices. One of the challenges with this material is the fabrication of the very small antennae and measuring their properties. We will be working in the cleanroom and using lithography techniques and electron microscopes for measuring and visualising the nanostructures’, Søren explains.

Devices are another interesting application for this technology. Personal devices are required to interact with and adapt to the user’s needs. Smart glasses are an example where in addition to correcting your eyesight, they are able to shade your eyes from the sun during the day and enhance your vision in the dark.

Finally, one could also imagine that this technology could improve lenses for video cameras and mobile phones. Today, mobile phones use digital zoom because optical zoom (which is far superior) requires moving lenses, which would increase the thickness of the phone. Active metasurfaces would be able to mimic the high quality optical zoom of a moving lens without any moving parts, thus not requiring any extra space.