Professor Soo Seok Choi's team, comprising first author Seungmin Nam, a POSTECH Electrical Engineering doctoral graduate and former postdoctoral researcher now Assistant Professor at Chosun University, integrated student Seohyeon Woo, and doctoral student Jiyoon Park, developed the first programmable stretchable optical encryption using stretchable multipixel/color separation. It was published online in March in Springer Nature's leading optics journal Light: Science & Applications, impact factor 20.6.
Rapid advances in AI and digital technology increase demand for correspondingly more complex and secure information encryption. Optical encryption, combining light and pattern information so data are revealed only under specified conditions and hidden otherwise, is growing worldwide. The source describes conventional digital encryption as vulnerable to advances in AI computation/analysis and argues that binary semiconductor combinations limit complexity, motivating more combinations and harder-to-decipher conditions.
The researchers maximized complexity by combining stretchability, multiple patterns, and multiple colors. Stretching was divided into precise strain conditions rather than simple on/off extension. Pattern information used sixteen pixels in a 4 × 4 array, while color covered continuous wavelengths across approximately 150 nm. Combining strain conditions, sixteen-pixel patterns, and wavelength combinations created a highly complex system.
Encrypted information combined with Base64 codes can be retrieved only under specific conditions among many possibilities. Yet stretching and color provide intuitive decoding when the required conditions are known. Chiral liquid-crystal elastomer materials enabling stretchable color changes and device parameters such as thickness provide combinations difficult to decode digitally, hindering arbitrary electronic, computational, or AI-based decryption and hacking.
The technology suggests possibilities for security/encryption devices, optical computing, analog computing, and other applications. Support came from the Samsung Science & Technology Foundation and the Korea Evaluation Institute of Industrial Technology's stretchable demonstration technology program.