Reviewed by Lexie CornerFeb 27 2025
Researchers have developed a doped form of photochromic glass capable of indefinite rewritable data storage, as reported in ACS Energy Letters.
A tiny cube of transparent glass holds these 3D designs that are revealed when exposed to specific lasers. Image Credit: Adapted from ACS Energy Letters 2025.
For many years, scientists have explored the possibility of storing data in glass due to its ability to retain information over long periods without requiring power. A specific type of glass, photochromic glass, which changes color in response to different wavelengths of light, has emerged as a promising candidate for stable and reusable data storage.
Certain eyewear lenses darken when exposed to sunlight and return to a transparent state indoors due to reversible photochromism. Similarly, some types of photochromic glass change color in response to different light wavelengths, making them a cost-effective and stable option for storing large amounts of data in compact spaces.
However, challenges remain in utilizing this material for continuous writing, erasing, and data rewriting. To address this, Jiayan Liao, Ji Zhou, Zhengwen Yang, and their multidisciplinary team advanced the technology by creating reversible and tunable patterns on photochromic gallium silicate glass.
The team synthesized gallium silicate glass modified with magnesium and terbium ions using doped direct 3D lithography. They used a 532-nanometer (nm) wavelength green laser to inscribe intricate 3D patterns—such as QR codes, symbols, geometric shapes, and even a bird—into small slabs of the modified glass.
The patterns appear purple in the otherwise transparent material and change colors when exposed to specific light wavelengths. When excited by a 376-nm deep violet laser, terbium emits green luminescence, while magnesium glows red under a 417-nm violet laser. The patterns can be erased completely by applying heat at 1022 ºF (550 ºC) for 25 minutes, without altering the glass structure.
The researchers also introduced the novel application of magnesium and terbium for their distinct luminescence at separate wavelengths, enabling tunable, multicolor retrieval of 3D patterns from a single material. This innovation has potential applications in high-capacity, durable 3D optical memory storage and encryption for industrial, academic, and military uses.
The study was funded by the National Natural Science Foundation of China, the Science and Technology Project of Southwest Joint Graduate School of Yunnan Province, the Key Project of the National Natural Science Foundation of China-Yunnan Joint Fund, and the National Natural Science Foundation of High-end Foreign Experts Introduction Plan.
The Academician Expert Workstation of Cherkasova Tatiana in Yunnan Province, the Yunnan Province Major Science and Technology Special Plan, the Preparation and Property Control of Luminescent Materials and Application in Plateau Agriculture, the University of Technology Sydney Chancellor’s Research Fellowship Program, and the National Health and Medical Research Council also provided funding for the study.
Journal Reference:
Zhao, H., et al. (2025) Direct 3D Lithography of Reversible Photochromic Patterns with Tunable Luminescence in Amorphous Transparent Media. ACS Energy Letters. doi.org/10.1021/acsenergylett.5c00024.