By layering thin film of electrochromic polymer over aluminum nanograting, NIST researchers have developed a new technology for building power-sipping full-color video displays, switches and routers for optical signals, as well as smart windows and coatings. In their setup, light first encounters nanograting which, depending on spacing of slits, filters out all but one color of light. Electrochromic coating serves to modulate that light by allowing all or some (or none) of it to pass.