Fujitsu claims to be able to double current storage capacity with new technology that will let you store one terabit per square inch - opening the way for huge 5TB computer hard drives.

The company demoed a key technology that will lead to larger capacity and smaller size hard disks - the optical element of a heat-assisted recording method (HARM) that produces sub-100nm spots on the disk drive surface and heats them with a laser.

This heating means that smaller magnetised areas can be created. As these can be packed closer together than with today's perpendicular recording technology, the areal density of the disk grows from around 421Gbit per square inch to 1Tbit. It opens the way to disk drives with up to ten times the capacity of today's drives, e.g. 5TB rather than 500GB.

Joel Hagberg, marketing and business development VP for FCPoA, talked of the achievement as "an exciting milestone for high density recording development, as well as for the storage industry as a whole."

Thermally assisting the recording method is seen by the disk drive industry as the most promising way of achieving higher storage densities through shrinking the magnetised spot size. Seagate calls its version HAMR - for heat-assisted magnetic recording.

Achieving it means adding a laser and optical element to the read/write head to focus the laser beam to the small spot size and transmit the laser beam efficiently to enable heating of the drive surface spot. Fujitsu used a layered optical element in the read/write head to achieve a spot size of 88nm by 60nm. It claims it is the first company in the world to achieve a sub-hundred nanometer optical spot with such a lens.

The head has three elements which the spinning disk platter passes under. In order they are: a read component; the laser light guide and optical element/heating component; and the magnetic writing component.

A package of read/write head and media technologies are needed to produce drives with a 1TB per square inch areal density. These include advancements in patterned media technology [pdf], a lubricant that allows for the lower head flying height needed to ensure smaller magnetised spots can be read and written, plus improvements in head material development.

It will be three to five years before HARM technology disk drives become available. Perpendicular recording technology will deliver a 1TB capacity drive next year. Seagate and Western Digital are bound to follow suit.