Dual Optical Information‐Encrypted/Decrypted Invisible Photonic Patterns based on Controlled Wettability

Abstract Invisible photonic patterns based on responsive photonic crystals show great potential in structural‐color encryption. However, single inherent information (structural color) encryption/decryption means and the incomplete invisibility in normal conditions greatly limit further development in high‐precision encryption. Here, a novel invisible photonic pattern encrypted/decrypted by dual optical information (structural color and brightness) is reported. It is prepared by engineering an extremely large wettability difference into the patterned and unpatterned regions of a vapor‐responsive inverse opal film. The same optical properties and the distinct wettability difference between the two regions not only ensure that the pattern encrypted by structural color and brightness in the normal state can be entirely hidden under the microscope, but also ensure that it can be decoded by large color contrast (Δλ = 26–32 nm) and brightness contrast (Δ B = 48–57.6) under flowing water vapor state. The unique invisible photonic pattern, reported for the first time, can inject new life into structural color‐based encryption.