The glass can accommodate 3D patterns that appear and disappear from light

Chinese researchers develop rewritable photochromic glass that changes color at specific wavelengths, providing the potential for long-term data storage

In a small transparent glass, the purple bird appears to float in three dimensions. Use the correct light and it will turn into a green or red glow. Then, with a little heat, it’s gone completely – a new pattern is ready to replace it.

This is not magic, but cutting-edge materials science from Chinese researchers, according to research published on February 26 in ACS Energy Letters, which creates a special type of glass that can store and display rewritable 3D patterns.

“We created a doped photon glass that has the potential to store rewritable data indefinitely,” said the research team led by Jiayan Liao, Ji Zhou and Zhengwen Yang, which developed materials at Kunming University of Science and Technology, a company’s science and technology and collaboration organization.

Glass works through a phenomenon called reversible light pigmentation, which is the basic principle that makes certain glasses darken in the sun and clear the room. However, when exposed to a specific wavelength of laser light, this specially made glass does not respond to sunlight, but changes.

While photochromic glass itself is nothing new, researchers have made significant progress by adding magnesium and magnesium ions to silicate glass. This combination not only allows for writing patterns, but also provides something special: the ability to display them in different colors under different lighting conditions.

Write with light, read with color

To create the pattern in the glass, the team used a green laser with a wavelength of 532 nanometers. Photo triggers chemical changes in glass, causing manganese ions to transfer from one form (Mn)²⁺) to another (mn³⁺), looks purple.

The most significant aspect is how to “read” these patterns. When illuminated with a dark purple of 376 nanometers, the terbium in the glass is green. In the purple of 417 nanometers, magnesium produces red light. This means that the same pattern can be viewed in different colors simply by changing the wavelength of the light used to check it.

“The researchers considered the groundbreaking features of magnesium and terbium to enable it to glow at distinct wavelengths, which makes it possible to obtain adjustable, multi-color readings of 3D patterns from a single material,” the authors noted in the paper.

To completely erase the pattern without changing the structure of the glass, the team heated it to 550 degrees Celsius (1022 degrees Fahrenheit) for 25 minutes. After cooling, the glass returns to its original transparent state, ready for a new pattern.

From QR code to data storage

The research team demonstrates various applications by writing complex patterns into glass. They created simple shapes such as yangyang symbols, as well as more complex designs such as QR codes, and even complex 3D geometric shapes such as triangles and hexagonal prisms that appear to float in transparent materials.

By focusing the laser to increase power, the researchers reached a resolution of about 5 microns, one-tenth of the width of human hair, and reduced writing time to just 20 milliseconds per point. This accuracy shows that the technology can eventually store large amounts of data in a very small space.

What makes data storage particularly promising is the stability of written patterns. The researchers found that even after five months, the information written to the glass was still clearly visible and showed excellent chemical stability.

Potential solutions to long-term data archives

Current methods of digital storage (from hard drives to flash)—will be reduced for decades and require maintenance of data. However, glass can potentially retain information for thousands of years without electricity.

This approach addresses several limitations of current optical storage technologies such as CDs and DVDs that rely on binary data storage with reflectivity differences. Photon glass provides multiple dimensions of data storage through the ability to encode information in three physical dimensions and color variations.

The potential application scope of this technology goes beyond data storage. Researchers believe it may be valuable for encryption in industrial, academic and military environments where information security is crucial.

The research is funded by a variety of scientific organizations in China, including the National Natural Science Foundation of China, as well as the Prime Minister’s Research Fellowship Program in Sydney, Australia and the National Health and Medical Research Council.

As data demand continues to multiply globally, this glass technology represents a promising direction for creating stable, high-capacity storage media that can potentially retain digital information for generations – appearing and disappearing with the command of light.