Engineers at the University of California San Diego have developed an optical switching technique that uses specialized ultrafast lasers to control magnetism, achieving speeds more than 1,000 times greater than conventional magnetic-field methods.
University of California San Diego Engineering Team Modifies Laser Beams
Modern data storage systems rely on tiny magnetic regions to store digital information as ones and zeros. Changing these states typically requires applying an external magnetic field, which consumes substantial energy and slows recording speeds. To bypass these limitations, researchers at the UC San Diego Jacobs School of Engineering redesigned the light itself rather than inventing a new material. By altering the shape and size of an ultrafast laser beam, the team reduced the beam’s footprint, with the researchers describing a reduction of tens of orders of magnitude to target microscopic regions directly.
“The smaller the size of the beam, the smaller and more dense the optical memory,” said study senior author Abdoulaye Ndao, professor in the Department of Electrical and Computer Engineering at the UC San Diego Jacobs School of Engineering.
Previous attempts at optical switching stalled because the method only worked on extremely thin magnetic structures containing three or fewer layers. Thicker materials suppressed the switching effect entirely. Furthermore, earlier experiments demanded light with a precise electromagnetic wave polarization.
Thicker Platinum And Cobalt Layers Resist Previous Constraints
Ndao’s research group overcame these physical barriers by concentrating laser energy into an exceptionally tight area and delivering a sequence of ultrafast pulses. The initial pulses heat a localized spot to reverse its magnetic orientation, while subsequent pulses expand that reversed zone until the new state stabilizes. This method successfully triggered optical switching in a nine-layer structure made of alternating platinum and cobalt films without requiring a specific light polarization.
“We’ve optically engineered the light to change the physics that’s happening in the material at the micro- and nanoscale,” said Muhammad Waleed Khalid, an electrical and computer engineering Ph.D. student and first author of the study published in Nature Communications.
The unusual results required extensive re-testing before the optics community accepted the findings. The breakthrough stemmed from a cross-disciplinary collaboration between Ndao’s optics team and Eric Fullerton, an expert in thin-film magnetic materials and professor of electrical and computer engineering and of chemical and nano engineering at UC San Diego.
Future Integration Challenges For Hardware Manufacturers
Despite the speed and density gains, significant hurdles remain before optical switching can move into commercial computer chips. Current ultrafast lasers are too bulky for standard electronic hardware integration. Researchers are now searching for magnetic materials compatible with more adaptable laser setups and aiming to shrink the beam size down to a few hundred nanometers using specialized optical structures.
“Instead of designing a new material to enable optical switching, we redesigned the light itself and showed new properties that were not previously thought to be possible,” Ndao said.
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