--- In email@example.com
, "Robert Karl Stonjek"
Right, left, left.
Artist's impression of how laser pulses could replace conventional
data transfers to magnetic disks by reversing the spin--and therefore
the polarity--of their photons.
Credit: Stanciu et al., Physical Review Letters
Lighting a Fire Under Hard Drives
By Phil Berardelli
ScienceNOW Daily News
28 June 2007
In the race to make computers more powerful, magnets may be out and
lasers may be in. Ultra-rapid pulses of polarized light fired from
lasers, new tests show, can outperform conventional magnetic data
writers by as much as two orders of magnitude. The technology could
form the foundation of a new generation of computers that link lasers
to their hard drives.
Long gone are the days when computers were required only to make
mathematical calculations. Even modest desktop models are now expected
to handle streaming audio and video from multiple Web sites
simultaneously, for example. Those functions require huge amounts of
data to be transferred quickly to and from the hard drive. But current
data-processing systems, which use magnets to write and read the
binary code that constitutes computer language, can only work so fast.
Some users' needs have begun to bump up against the limitations of
this technology. If computers are to become faster, they'll require a
different data-transfer system, and the awesome promise of quantum
computing remains years away.
Researchers at Radboud University Nijmegen in the Netherlands think
they've found another candidate. In laboratory experiments, they used
laser light to write data to a magnetic hard drive at very high
speeds. The technique works because the photons transmitted by the
laser actually carry angular momentum, allowing them to interact with
the hard drive. Also, each laser pulse heats a tiny space on the disk
just enough to make changing its polarity--thereby storing a bit of
data--a little easier. The key is reversing the polarity of the laser
pulses, which can produce the equivalent of either a 1 or a 0 of
binary code on the disk storage medium.
The researchers managed to transfer data at intervals of about 40
femtoseconds, or quadrillionths of a second, about 100 times faster
than conventional magnetic transfers, the researchers report in a
paper accepted for publication by Physical Review Letters. One
drawback is that the footprint of the laser pulse on the disk is about
5 microns wide, which is considerably larger than the footprint
produced by existing data-transfer systems. But physics doctoral
candidate and co-author Daniel Stanciu says the team is working on
improvements in the technology that should reduce the footprint's size
to about 10 nanometers, and he expects to see a working prototype
within a decade.
"This is one of the most exciting stories in magnetics," says
physicist Julius Hohlfeld of Seagate Research in Pittsburgh,
Pennsylvania. Lots of other researchers have tried to employ polarized
laser light to write data, he says, but everyone failed because the
magnetic alloys they used for the storage medium did not work. But the
disk made of gadolinium, iron, and cobalt that Stanciu's team used has
succeeded. The next challenge, Hohlfeld says, will be to find a
relatively cheap laser technology that can fire pulses lasting less
than 100 femtoseconds.
Robert Karl Stonjek
--- End forwarded message ---