This Glass Can Hold 3D Patterns That Appear and Disappear at the Flick of a Light

Chinese researchers develop rewritable photochromic glass that changes color under specific wavelengths, offering potential for long-term data storage

Inside a small cube of clear glass, a purple bird seems to float in three dimensions. With the right light, it transforms to glow green or red. Then, with a bit of heat, it vanishes completely—ready for a new pattern to take its place.

This isn’t magic but rather cutting-edge materials science from researchers in China who have developed a special type of glass that can store and display rewritable 3D patterns, according to research published February 26 in ACS Energy Letters.

“We’ve created a doped photochromic glass that has the potential to store rewritable data indefinitely,” said the research team led by Jiayan Liao, Ji Zhou, and Zhengwen Yang, who developed the material at Kunming University of Science and Technology and collaborating institutions.

The glass works through a phenomenon called reversible photochromism—the same basic principle that makes certain eyeglasses darken in sunlight and clear up indoors. But instead of responding to sunlight, this specially crafted glass changes when exposed to specific wavelengths of laser light.

While photochromic glass itself isn’t new, the researchers made a significant advance by adding magnesium and terbium ions to gallium silicate glass. This combination allows not only for writing patterns but also provides something special: the ability to display them in different colors under different lighting conditions.

Writing with Light, Reading with Color

To create patterns in the glass, the team used a green laser with a wavelength of 532 nanometers. The light triggers a chemical change in the glass, causing manganese ions to shift from one form (Mn²⁺) to another (Mn³⁺), which appears purple.

The most remarkable aspect is how these patterns can be “read.” When illuminated with deep violet light at 376 nanometers, the terbium in the glass luminesces green. Under violet light at 417 nanometers, the magnesium produces red light. This means the same pattern can be viewed in different colors simply by changing the wavelength of light used to examine it.

“The researchers consider the use of magnesium and terbium groundbreaking for their abilities to luminesce at distinctly different wavelengths, which makes it possible to get a tunable, multicolor readout of 3D patterns from a single material,” the authors note in their paper.

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

From QR Codes to Data Storage

The research team demonstrated various applications by writing complex patterns into the glass. They created simple shapes like a yin-yang symbol, as well as more complex designs like QR codes, and even intricate 3D geometric shapes like triangular and hexagonal prisms that appear to float inside the transparent material.

By focusing the laser to increase power, the researchers achieved a resolution of approximately 5 micrometers—roughly one-tenth the width of a human hair—and reduced the writing time to just 20 milliseconds per point. This precision suggests the technology could eventually store large amounts of data in a very small space.

What makes this particularly promising for data storage is the stability of the written patterns. The researchers found that information written into the glass remained clearly visible even after five months, demonstrating excellent chemical stability.

A Potential Solution for Long-Term Data Archives

Current digital storage methods—from hard drives to flash memory—typically degrade within decades and require power to maintain data. Glass, however, could potentially preserve information for thousands of years without power.

This approach addresses several limitations in current optical storage technologies like CDs and DVDs, which rely on binary data storage with reflectivity differences. The photochromic glass offers multiple dimensions of data storage through its ability to encode information in three physical dimensions plus color variations.

The technology’s potential applications extend beyond data storage. The researchers suggest it could be valuable for encryption in industrial, academic, and military settings, where information security is paramount.

The research was funded by various Chinese scientific organizations, including the National Natural Science Foundation of China, as well as Australia’s University of Technology Sydney Chancellor’s Research Fellowship Program and the National Health and Medical Research Council.

As data needs continue to grow exponentially worldwide, this glass technology represents a promising direction for creating stable, high-capacity storage media that could potentially preserve our digital information for generations to come—appearing and disappearing at the command of light.