Memory Crystals: 'It Seemed to Defy the Laws of Physics'

Big data is becoming a big problem. In the face of rising emissions from data centres, researchers are turning to novel solutions for storage. Memory crystals and DNA are two frontrunners.

On a visit to Japan in 1999, researcher Peter Kazansky encountered a mysterious physical phenomenon that he now believes holds the answer to the future of data storage.

In Kyoto University's optoelectronics lab, scientists were experimenting with writing on glass using ultrafast, femtosecond lasers which emit a light pulse every quadrillionth of a second.

But they noticed something unusual about how light was travelling through the glass that had been lasered. Rayleigh scattering is a well-established effect which describes how white light bounces off small particles in all directions (explaining, among other things, why the sky appears blue). But in this case, the light wasn't bouncing as expected.

"It was difficult to explain," says Kazansky, a professor in optoelectronics at the University of Southampton in the UK, who was collaborating with the Kyoto University researchers. "We saw light scattering in a way that seemed to defy the laws of physics."

The puzzling observation eventually sparked "a real eureka moment", says Kazansky. The researchers discovered hidden nanostructures within the silica glass that had been created by "micro-explosions" from the femtosecond lasers.

Imagine holding a thick rock of crystal up to the sun and seeing light ricocheting off it in many different directions. With the lasering technique, the Kyoto researchers had accidentally created tiny holes that had the same property.

Some 1,000 times smaller than the breadth of a human hair, these "whirlpools" of light are so tiny as to be indiscernible to the human eye. But it soon became clear to the scientists that they had a potentially transformative utility. "This was the first proof that we could use light to 'print' complex patterns inside transparent materials at a scale smaller than the wavelength of light," says Kazansky.   

Now, 27 years later, he hopes the discovery can help solve one of the most intractable problems of our information age: mass data storage.

- Author: Laurie Clarke, BBC