Counterfeiting results in significant losses worldwide and consequently, there is an obvious need for the constant development of security devices in order to stay one step ahead of counterfeiters. In addition, as passive optical devices based on metal-dielectric filters are becoming easier to imitate by use of commercially available iridescent materials, the addition of new optical effects becomes critical. Active materials, such as electrochromic (EC) WO_3 which colors upon the insertion of electrons and ions, can play such a role. In the present work, we combine both the angular color-shifting properties of a Fabry-Perot-like metal-dielectric filter with the contrasting coloration when voltage is applied to an EC device. This results in a 2-level authentication device of potential use for the next generation of security features. The same technological advancements may also be of use to smart windows, where control of the color of the windows is of critical importance in modern architectural design.
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