Dielectric Multilayer Films Fabricated by Magnetron Sputtering: How Far Can the Iridescence Be Tuned?

Periodic dielectric multilayer structures can generate interferential colours from optically transparent basic materials. Their iridescence property, i.e. the change of colour with the illumination or viewing angle, is exploited in the industry to produce structurally coloured coatings and paints. Magnetron sputtering is an efficient technique for producing multilayer films owing to its ability to deposit films on large surfaces with excellent uniformity and reproducibility in both the film thickness and composition. Based on a theoretical model of the optical response, we investigated the iridescence tuning range of the technologically important SiO2/TiO2 material system. Radically different iridescent behaviours were predicted theoretically and demonstrated experimentally by selecting appropriate combinations of period and layer thickness ratio.