Plasmonic Color Filters as Dual‐State Nanopixels for High‐Density Microimage Encoding

Plasmonic color filtering has provided a range of new techniques for “printing” images at resolutions beyond the diffraction‐limit, significantly improving upon what can be achieved using traditional, dye‐based filtering methods. Here, a new approach to high‐density data encoding is demonstrated using full color, dual‐state plasmonic nanopixels, doubling the amount of information that can be stored in a unit‐area. This technique is used to encode two data sets into a single set of pixels for the first time, generating vivid, near‐full sRGB (standard Red Green Blue color space)color images and codes with polarization‐switchable information states. Using a standard optical microscope, the smallest “unit” that can be read relates to 2 × 2 nanopixels (370 nm × 370 nm). As a result, dual‐state nanopixels may prove significant for long‐term, high‐resolution optical image encoding, and counterfeit‐prevention measures.