Taking the metal out of metamaterial

Abstract

A flash of light is all it takes to convert a metal-free metamaterial from a state that blocks certain wavelengths of light to one that transmits them, according to a study (App. Phys. Lett. 2016, DOI: 10.1063/1.4959272). The advance could lead to photonic and optoelectronic devices for use in telecommunications and other areas. Metamaterials exhibit unnatural properties—for example, the ability to selectively reflect, absorb, or transmit light or sound—by virtue of the geometry of their engineered structures. Many metamaterials are made from metals. This includes versions that switch between “on” and “off” states in response to electric or thermal stimulus. Because metals generally absorb visible and infrared light, these metamaterials can’t be used in various optical devices. So Kevin F. MacDonald and coworkers at the University of Southampton used a 300-nm-thick film of germanium antimony telluride (Ge2Sb2Te5), or GST, to make a grating featuring parallel lines of GST, roughly 750