From Costa Rica to Meta’s Latest Plasmonic Banknote Security Features

Meta Materials Inc. (previously Nanotech Security Corp) has been a pioneer in banknote OVD (Optically Variable Device) technology for the past decade with innovations in micro-, nano- and now plasmonic structures. The company has also developed in-house secure foil production so that it can offer banknote stripes direct to customers.

The physics of surface plasmons deals with phenomena that occur at an interface, or boundary, between a dielectric (an insulator whose electric charge can be shifted without flowing) and a metal (a conductor whose electric charge can flow). Under certain controlled conditions, energy, in the form of electromagnetic excitations, moves along the interface between the dielectric and the metal in the form of a wave. These so-called evanescent waves are trapped and can only move in particular directions. The plasmons can be controlled through careful modelling and application of, amongst other things, the dielectric and metal layer thickness in a ‘sandwich’ structure.