Scalable and flexible covert polarization displays

Researchers have developed numerous applications with structural colors, among them the creation of sophisticated security features for anti-counterfeiting. Covert polarization displays, for instance, provide a barrier to the inadvertent viewing of encrypted optical information without compromising packaging aesthetics. To break through the flexibility/scalability limitation of existing systems, researchers have now developed a large-area covert polarization display technology by using ultrathin lossy nanocolumns deposited on a metal film. This clever strategy for switching covert optical information uses polarization-dependent multicolors without structurally sophisticated fabrication processes.