Plasmonic nanostructures represent an emerging class of novel optical technologies for the anti-counterfeiting industry. The phenomenon of surface plasmon resonance, arising from the resonant interaction of light with a nanostructured surface, can provide both overt and covert effects that are governed by physics that is principally distinct to traditional optically variable devices (OVDs).
We present the development of a platform technology that utilises laser-induced generation of plasmonic nanoparticles to create optically variable effects that are controlled by localised surface plasmon resonance (LSPR) – whereby spatial manipulation of a highly-localised heating effect allows for the selective nanostructuring of thin metal films on a range of industry-compatible polymers and the production of highresolution and easily identifiable optically active features.
We discuss the potential applications, highlighting that the optical effects arising from LSPR (such as an enhanced or reduced reflectivity, transmission, or absorption) are particularly suited for transparent substrates and can be tuned to produce a highly-controllable and reproducible colour gamut. Additionally, the laser-processing method aligns well to digitallydriven requirements, by allowing for the embedding of uniquely identifying information (i.e. numbering, barcoding, etc.), as well as affording the ubiquitous benefits of laser-based manufacturing, namely; scalable, large-area and rapid processing.