Although optical discs are no longer widely used, scientists may have found a means to increase their data storage capacity by several times.
In February, scientists from the Shanghai Institute of Optics and Fine Mechanics, the University of Shanghai for Science and Technology, and other Chinese universities stated that they had successfully shown the ability to fit more than a petabit (125 terabytes) of data onto a single optical disk. That surpasses the capacity of the largest hard disk in the world, a $40,000 monstrosity that can store 100 terabytes.
CD-ROMs, DVDs, and Blu-rays are examples of older optical storage devices that store data in one, two, or even four layers. The researchers assert that recent developments in optical technology, chief among which is an ultra-transparent film known as “aggregation-induced emission dye-doped photoresist” (AIE-DDPR), have made it possible for them to store 200 terabytes (1.6 petabits) of data on a single disc the size of a typical disc and to encode data on as many as 100 layers.
The scientists revealed they were able to blast beyond the optical diffraction limit, which is the smallest point an optical imaging system can resolve, using AIE-DDPR in conjunction with twin lasers, according to ZME Science. That has historically only applied to the size of the light wavelengths that an optical device produces.
The Chinese researchers said that they were able to encode and read data from spots that were about a tenth of the wavelength of the visible light used in the optics by carefully regulating the firing periods of two sets of dual lasers that were used for reading and writing to the disc and by employing the AIE-DDPR material. The investigation found that all 100 layers on the disc had similar write quality and are spaced apart by roughly one millimeter.
According to Min Gu, an optical-electrical and computer engineering professor at the University of Shanghai, “it has been a 10-year effort searching for this kind of material,” as she stated to IEEE Spectrum. “The challenge has been determining how the processes of writing and reading interact in a given material—specifically, in a three-dimensional geometry.”
Gu continued, expressing his surprise at how effectively the material handled reading at the nanoscale level as well as writing-recoding. The researchers tell IEEE Spectrum that the discs can probably be produced in roughly six minutes each using methods that are similar to those used to make DVDs.