Diamond is a promising material for data storage, and now scientists have demonstrated a new way to write more data into it, even into individual atoms.This technology bypasses physical limitations and writes data to the same spots using different colors of light. Diamond has huge potential as a data storage medium - recent developments have produced 2-inch (5cm) diamond wafers that can store the equivalent of a billion Blu-ray discs.
Interestingly, it works by writing data not into the diamond itself, but into tiny nitrogen defects in the material. These defects absorb light and are therefore called "color centers."
Typically, optical storage technologies have a hard limit on how finely they can write data - after all, there is a limit to the smallest diameter a laser beam can be focused to. This diameter is called the diffraction limit and is proportional to the wavelength of light used.
Tom Delord, co-author of the study, said: "You cannot use such a beam to write data with a resolution smaller than the diffraction limit, because if you shift the beam smaller than the diffraction limit, it will affect the data that has been written. So, normally, optical memory increases storage capacity by shortening the wavelength (shifting to blue), which is why we have 'blue light' technology."
But in this new study, researchers at the City University of New York (CUNY) found a way around diffraction limitations. The trick is to use different wavelengths of light to write data to the center of the color closer than the diffraction limit - for example, it may not be possible to put two "greens" side by side, but if you alternate green, red, and blue, you can theoretically store three times more data in an area than with a single color.
"What we've done is use a narrow-band laser and cryogenic conditions to very precisely control the charge in these color centers," Delord said. "This new method allows us to write and read tiny bits of data at a much finer level than before, even down to individual atoms."
In tests, the research team demonstrated that the technology can imprint 12 different images at different frequencies at the same location, with a data density of 25GB per square inch (6.4 square centimeters). By comparison, a standard single-layer Blu-ray disc only has so much capacity on its entire surface. As an added bonus, the technology is reversible, so data can essentially be written, erased, and rewritten as many times as needed.
The team says that with further work, the technique could be applied to other materials and potentially at room temperature rather than cryogenic conditions.
The research was published in the journal Nature Nanotechnology.