Adv.Opt.Mat.http://dx.doi.org/10.1002/adom.201400105(2014)

By coating a highly reflective gold-film mirror with a thin layer of polystyrene doped with a photochromic spirooxazine polymer, researchers have created a photoswitchable super absorber. Mady Elbahri and co-workers say that the reflectivity of the metal mirror, which is usually very high, can be reduced to just a few percent by illuminating it with ultraviolet light. The structure's reflectivity can then be switched back to a high value by applying visible light. This dramatic change in the optical characteristics is due to the photochromism of the spirooxazine molecule, whose C–O bonds break when it is illuminated with ultraviolet light, causing it to become highly absorbing in the 500–700 nm wavelength window. By placing the structure in a cavity, it was possible to optically switch between weak and strong plasmon coupling. This approach may prove useful for sensing applications and for creating optically controlled plasmonic switches.