Control of Asymmetric Scattering Behavior of Plasmonic Nanoparticle Ensembles

A transparent or translucent film shows the same color for both front and back sides in general. However, different colors can be shown by the aid of strong plasmonic scattering of metal nanoparticles. Here we propose a design strategy of films exhibiting asymmetric scattering behavior. Typically two different types of nanoparticles are embedded in a SiO2 thin film that is coated on a TiO2 thin film. One of the particle types is selectively excited for the front incidence, and the other type for the back incidence, by tuning the electric field distribution inside the SiO2 film. We experimentally prepared two different samples that scatter light of different colors from the front and the back sides by using Au nanorods and Ag nanospheres.