Flexible All-Optical Steganographic Information Encryption Technique Based on Photoisomerized Polymer Films

In this work, a high-compact, high-density, and high-precision light-steganography information encryption technique is proposed through an all-optical controlled rewritable approach. The numerical or visual information protected is set using commercial SU-8 photoresist on a flexible substrate by direct UV lithography. The related information disguised is formed using a photoisomerized polymer on the SU-8 layer by the overlay lithography method. 365 nm UV light and 632 nm visible light are featured as pumping sources for the optical encryption and decryption process, with the threshold driving power of 130 mJ/cm 2 and 120 mJ/cm 2, respectively. The fabrication tolerance is obtained as less than 1 μm. The all-optical rewritable response time is lower than 10 s. This light-steganography information encryption technique is suitable for significant applications such as data security, covert communication, and copyright protection.