The process integrates optical elements as part of the manufacturing process for the hard drive. A lens is used to focus an extremely tight beam onto the magnetic platter. The beam heats the platter which allows easier recording on the magnetic media. Using a specially designed optical element, Fujitsu was able to attain a spot size of 88nm by 60nm with 17 percent optical efficiency.
Imagine having a 500GB iPod, or a laptop with 2 500GB HDDs in the space you formerly fit a single 2.5” in. Release dates for drives using such a technology haven't been made available, and nor have potential capacities. It sounds incredibly useful though.