Optical Janus Effect in Large Area Multilayer Plasmonic Films

Abstract

Plasmonic and other nanoparticles have attracted considerable interest for their role in structural coloration. The optical “Janus” effect, where the color of light reflected from a partially transmitting film depends on whether the device is viewed from the substrate or the coating side, is observed using a variety of nanostructured films. Herein, the optical Janus effect produced by homogeneous thin-film structures comprising only four layers of three different materials with a total thickness less than 300 nm is demonstrated. An asymmetric Fabry–Perot (FP) nanocavity is formed with a dielectric film bounded by two different metal films of nanoscale thickness. The semitransparent device ha..