Strategy for steganography and information encryption-decryption using Fs laser-created luminescence in organic...

Functional materials, especially luminescent ones, are attracting increasing attention in the field of information security due to their potential in advanced steganography, information encryption-decryption, and anti-counterfeiting (IEDAC) technologies. However, current luminescence based IEDAC methods face several challenges, including risks of information leakage, ease of duplication, and sensitivity to environmental conditions, which limit their practical application. In this work, we demonstrate an IEDAC approach utilizing photoluminescence (PL) emission patterns generated by infrared femtosecond (fs) laser direct writing with their properties further tailored via post-exposure to linearly polarized continuous-wave (CW) laser. This method enables hierarchical two-level information storage: level-1 information is inscribed by creating PL in an organic substrate using fs laser direct writing, while level-2 information is concealed and encrypted through polarization-dependent excitation anisotropy in PL, which arises from polarization-selective bleaching of asymmetric luminophores induced by linearly polarized CW laser exposure. This technique not only allows polarization-based encoding, but also enhances security against brute-force attacks and reduces susceptibility to the environment. Validated across three different organic materials, with detailed results presented for Zeonex polymer, this method not only demonstrates its effectiveness but also suggests a versatile and universal approach for advancing IEDAC technology in the field of information security.