A new optical metamaterial makes true unidirectional glass possible

Researchers at the University of Alto have adopted a new approach to create a metamaterial that exceeds the technological scope that has emerged so far. Unlike natural materials, metamaterials and metasurfaces can be customized to have specific electromagnetic properties, which means scientists can create materials with the characteristics required for industrial applications.

The new metamaterial utilizes the non reciprocal magnetoelectric effect. The NME effect implies a connection between the specific characteristics of a material and the different field components of light or other electromagnetic waves. The NME effect can be ignored in natural materials, but scientists have been trying to use metamaterials and metasurfaces to enhance it, as this will unleash technological potential.

The research findings are published in the journal Nature Communications.

"So far, the NME effect has not brought practical industrial applications. Most proposed methods are only applicable to microwaves and not to visible light, and they cannot be manufactured using existing technology," said Shadi Safaei Jazi, a doctoral researcher at Alto. The team has designed an optical NME metamaterial that can be created using existing technology, traditional materials, and nanofabrication techniques.

This new material opens up applications that originally required a strong external magnetic field to work, such as creating true unidirectional glass. The glass currently sold as "one-way" is only semi transparent, allowing light to pass through in two directions. When the brightness on both sides is different, it is like one-way glass. However, unidirectional glass based on NME does not require brightness differences, as light can only pass through it in one direction.

"Imagine having a window with glass in your house, office, or car. No matter how bright the outside is, people can't see anything inside, and you can enjoy the perfect view from the window," Safaei said. If the technology is successful, this unidirectional glass can also improve the efficiency of solar cells by blocking the thermal radiation from existing batteries to the sun, thereby reducing the energy they capture.

Source: Laser Net