Intelligent Machines

Higher-Density Data Storage

A novel nanolaser could cram more data onto a hard disk.

Dec 12, 2007


Spot light: To make a laser that focuses nanowatts of power into a 30-nanometer spot, researchers cover a semiconductor diode with an aluminum film etched with different nanoscale apertures. A scanning near-field optical-microscope image shows that the most laser light comes out from the C-shaped aperture.


The smaller the light spot of the laser, the smaller the bit size, which means more bits per square inch. Right now, the laser can concentrate 250 nanowatts of power on a 30-nanometer-wide spot. “Our technology can be scaled down to 5 to 10 nanometers for sure,” says Sakhrat Khizroev, an electrical-engineering professor who is leading the work at UCR. A 10-nanometer spot size should be small enough to get a density of 10 terabits per square inch.


Hard-disk manufacturers such as Seagate are now looking at a new method to store more data on disks. The technique, called heat-assisted magnetic recording, involves using a tightly focused light spot to heat up the bits when they are being recorded. This gives the magnetic crystals energy to retain their magnetic-field orientations. “There are various ways one could imagine bringing light on the disk,” says Mark Kryder, an electrical- and computer-engineering professor at Carnegie Mellon University. “The most elegant way would be to use a nanolaser.”


Ed Schlesinger, head of the Electrical and Computer Engineering department at Carnegie Mellon, says that the new nanolaser is “an important aspect of making heat-assisted magnetic recording a reality.” But he cautions that there are many engineering challenges to solve before the technology can be brought to market. They include mounting the laser on a slider so that it can move to various areas of the hard disk to record data, designing a new disk material that works with heat-assisted recording, and making disk lubricants that can handle the high temperatures during the heat-assisted writing process.

“Heat-assisted magnetic recording is a real systems problem and requires development and progress on a lot of fronts simultaneously,” Schlesinger says. “The nanolaser is a nice step forward and brings the technology closer.”