📄 Showing the "Simple" version — "Advanced" is not ready yet. Add it to favorites to help prioritize it. Ask for the full read

Imagine blinds that don't just block or let through light but change its color. Light hits the slanted stripes, and some rays come out a different shade, as if a white beam, passing through the slits, turned green. That's exactly how this new surface works: on a thin film of lithium niobate (a material that can transform light), there are slanted stripes of titanium dioxide. When light strikes them, part of it is converted into light at twice the frequency: this is called frequency doubling.

The key trick is that the stripes are slanted. This makes light linger longer inside the film, like water in a bent hose, giving it more time to interact with the material. So even weak light from an ordinary bulb produces a noticeable effect. The researchers tested it: a surface the size of a fingernail converts light with an efficiency of 0.15% per square centimeter at a power of one gigawatt — one of the best figures among similar lithium niobate devices.

This surface can be printed in large sheets, like wallpaper, using nanoimprint lithography: it's cheap and fast. By changing the angle of the incoming light, you can smoothly tune the output color from 870 to 920 nanometers (that's the infrared range, invisible to the eye but important for technology). The brightness remains stable. You can also control the polarization of light — roughly speaking, the direction of the light wave's oscillation, like turning a hose that's spraying water.

In the future, such surfaces could be used in sensors that detect the slightest changes in the environment, for generating terahertz waves (which can see through clothing and packaging), and for ultrafast processing of optical signals in compact devices.