Rewritable grating made of metamaterial with nanostructure

A metamaterial was fabricated by capsulating photochromic solution in nanoholes of polycarbonate. Nanoholes not only provided sufficient free volume for dye molecules to change structure for coloration, but also prevented the solution to flow and disturb an optically-induced grating pattern. The material exhibited a blue color by ultraviolet irradiation, and returned to the original transparent state when photobleached with visible light. A grating pattern was written in the material by irradiating an interference fringe of green laser. This grating pattern could be erased by ultraviolet irradiation, and a grating with a different period could be written in the same film.