Lasers Give Disk Drives a Huge Boost
Researchers user lasers to increase disk write speeds by one hundred times over current drives.
Chris Mellor, Techworld
Thursday, July 05, 2007 8:00 AM PDT
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Researchers have demonstrated disk write speeds one hundred times faster than current hard drives. The method uses a laser to heat the recording surface and alter its magnetic field. There is no equivalent read speed increase though.
According to a report in Science Now, Dutch scientists at Radboud University Nijmegen used a laser to send flashes of polarized light to a 5-micron-wide spot on a disk surface which was heated. The sheer angular momentum of the photons hitting the recording surface was then able to flip the magnetic field if the light was polarized one way, but left it unaltered if polarized in the other direction. A traditional magnetic field reader was then able to detect binary ones or zeroes accordingly.
This shows the promise of heat-assisted magnetic recording (HAMR).
The laser flash duration was 40 femtoseconds -- 40 billionths of a millionth of a second -- which is 100 times shorter than the time needed for a current write head to change the magnetic field direction on a hard drive disk recording bit. Thus there is the promise of increasing data writing speed up to one hundred times. This will enable hard disk data writing speed to better keep up with ever-faster data transfers across networks.
However there are problems to be resolved. Firstly the recording area, at 5-microns wide, is very much bigger than the sub-half micron area in today's hard drives. Drive users won't accept a substantial decrease in areal density, meaning lower disk capacity, as the price of a substantial speed increase. However, the researchers expect to get it down to a 10 nanometer area.
A second problem is that the read component of the disk head remains magnetic and there is, as yet, no technology promising a hundredfold increase in read speed.
Physicist Julius Hohlfeld of the Seagate Research establishment in Pittsburgh says that a third problem is the need to have an affordable laser that can fire 40 femtosecond pulses.
Daniel Stanciu, co-author of the research paper, expects a working prototype within ten years, which means that a commercial product could be 13 to 15 years away. That would take us to 2019 or thereabouts. Seagate has suggested that HAMR could increase area density to 50Tbit/sq inch by 2019, meaning a 40-50TB 2.5-inch hard drive would be theoretically possible.
