'Nanofishnet' Could Be the First Metamaterial to Impossibly Bend Light in the Visible Spectrum: Visible light has been a particularly tough nut to crack when it comes to metamaterials, which essentially bend light unnaturally to achieve a desired effect. Light waves in the visible spectrum tend to degrade to nothing after passing through materials just a fraction of a wavelength thick, so it’s tough to make a metamaterial that can bend light in a predetermined way without also losing the visible light wave altogether.
The UK/Spanish team (from King’s College London and the Valencia Nanophotonics Technology Center, respectively) overcame this through a novel layered construction of silver and hydrogen silsesquioxane (a type of glass). Using a focused ion beam, they punched tiny holes through the layers to create a structure they refer to as a “nanofishnet.” This combination of materials, layering, and nanofishnet structure allows the material to create the necessary negative magnetic permeability (a necessary ingredient for metamaterials that you can learn more about here) in the red and near-infrared parts of the spectrum.
By varying the size of the holes in the nanofishnet the team was able to adjust the materials index of refraction, giving them some degree of freedom when it comes to “programming” the material for different kinds of light.