Light control

A team of researchers from Rensselaer Polytechnic Institute has created the world’s first material that reflects virtually no light.

Reporting in the March issue of Nature Photonics, they describe an optical coating made from the material that enables improved control over the basic properties of light. The research could open the door to much brighter LEDs, more efficient solar cells, and a new class of "smart" light sources that adjust to specific environments, among many other potential applications.

Most surfaces reflect some light. The new material has almost the same refractive index as air, making it an ideal building block for anti-reflection coatings. It is said to set a world record by decreasing the reflectivity compared to conventional anti-reflection coatings by an order of magnitude.

A fundamental property called the refractive index governs the amount of light a material reflects, as well as other optical properties such as diffraction, refraction, and the speed of light inside the material. ‘The refractive index is the most fundamental quantity in optics and photonics. It goes all the way back to Isaac Newton, who called it the “optical density,”’ said E. Fred Schubert, the Wellfleet Senior Constellation Professor of the Future Chips Constellation at Rensselaer and senior author of the paper.