How to Fit 1,000 Terabytes Onto a DVD
DVDs and Blu-Rays don’t get a lot of respect from technophiles, because the optical disks aren’t able to store as much data as a typical hard drive. A team at Swinburne University in Australia could change that, by making it possible to store an entire year’s worth of video onto an optical disk. That could be good news for movie buffs but would also appeal to big data centers that who prefer to store the tremendous amounts of information they save in the least amount of space.
Storing data on conventional DVDs and Blu-Ray disk involves a single laser that burns a mark into the disk’s surfacing, changing its chemistry. The mark represents a 1 or 0, which is the basic binary language of all computer data. But because the marks can’t be smaller than a half the wavelength of the laser beam, there is a limit, to how many marks can be burned into the surface of a disk.
The Swinburne team, led by optoelectronics professor Min Gu, did something different. They used two lasers instead of one.
Each laser beamed a different wavelength of light onto the disk. The first one was in the near-infrared and created a spot of light, just like an ordinary DVD laser. The second laser beam was violet and partially interfered with the near-infrared beam in a way that ultimately shrank the spot burned into the disk. The technique shrank the size of the spot down to nine nanometers, enough to put 1,000 terabytes on a disk. For comparison, a Blu-Ray disk can hold 50 GB of data and a typical DVD holds about 4.7 GB of data.
The lasers are similar to those used in current players, so building a commercial version wouldn’t require any new technologies. Not too far in the future, the behemoth storage capacity of the Blu-Ray disk might seem as quaint as the 1.4 megabyte floppy disk.