Covert Images Using Surface Plasmon‐Mediated Optical Polarization Conversion

Covert optical signatures are a vital element in anticounterfeiting technologies. Plasmonic surfaces offer a means of manipulating the properties of light including the realization of colored pixels and images. In this work, concealed images with accurate color reproduction using plasmonic pixel arrays are demonstrated. The spectral and spatial control of optical polarization conversion is accomplished by tailoring the interaction of light with surface plasmons through the design and arrangement of surface nanostructures. The latent image is revealed using a polarization-sensitive optical system, which represents a means for the authentication of security features that can be created using these nanostructured devices. A red-green-blue color space is defined containing a wide gamut of chromaticities, enabling comprehensive full-color image capability. The device concept extends the functionality of a polarization-dependent plasmonic response to realize the encoding of a color image in covert form.