Engineers at the University of California San Diego have demonstrated an optical switching technique using a specialized ultrafast laser that could make computer memory over 1,000 times faster, more compact, and more energy-efficient by controlling magnetism with light instead of external magnetic fields.
University of California San Diego Engineers Target Speed Limits in Data Storage
Modern hard drives and storage systems rely on tiny magnetic regions to encode digital information as 1s and 0s. Writing new data usually requires applying an external magnetic field to change the orientation of these regions. This conventional process consumes considerable energy and imposes strict limits on recording speeds. Researchers published findings in Nature Communications demonstrating an alternative that utilizes light to change these magnetic states.
Light can deliver energy in extremely short bursts and can be focused onto remarkably small areas. This physical property allows magnetic information to be written much faster and with significantly less energy. According to the research team, optical switching could achieve speeds more than 1,000 times greater than traditional methods dependent on external magnetic fields.
Overcoming Thickness and Polarization Barriers in Optical Switching
Until now, optical switching faced two critical technical restrictions. Earlier experiments had only succeeded with extremely thin magnetic structures containing no more than three magnetic layers. Furthermore, the process required light with a particular polarization, demanding that its electromagnetic waves be oriented in a specific way.
Increasing material thickness beyond three layers suppressed optical switching, which constrained the overall thickness of the magnetic material and its long-term memory retention capabilities. To bypass these obstacles, engineers used a specialized ultrafast laser and carefully modified the shape and size of its beam. The resulting beam was dramatically smaller than those employed in earlier experiments, featuring a reduction of tens of orders of magnitude.
Through careful adjustment of the laser beam’s dimensions and profile, the investigators successfully carried out optical switching within a considerably thicker magnetic architecture built from nine alternating strata of cobalt and platinum. The experiments also proved successful without requiring a particular polarization of light.
“We’ve optically engineered the light to change the physics that’s happening in the material at the micro- and nanoscale,” explained Muhammad Waleed Khalid, the primary author of the study and a Ph.D. candidate in electrical and computer engineering working within Ndao’s laboratory.
The technique concentrates laser energy into an extremely small region and delivers a sequence of ultrafast pulses. A targeted area of the magnetic material receives a brief thermal boost from the initial pulses, which prompts a localized flip in its magnetic orientation. Additional pulses gradually enlarge that reversed region until the new magnetic state becomes stable.
“Working with a specialized laser allowed us to optically engineer the beam to have a certain shape and size,” Khalid added. “That gave us the room to explore more fundamental physics, which cannot be done with conventional beam lasers.”
Bridging Optics and Magnetic Materials for Higher Density Storage
The senior author of the research is Abdoulaye Ndao, who serves as a professor inside the Department of Electrical and Computer Engineering at the UC San Diego Jacobs School of Engineering. Rather than developing a completely new material to enable optical switching, the team redesigned how light interacts with an existing material. Directing laser energy onto smaller magnetic regions allows future memory devices to hold significantly more information without increasing their physical size.
Ndao stated that instead of designing a new material to enable optical switching, the team redesigned the light itself and showed new properties that were not previously thought to be possible. “The smaller the size of the beam, the smaller and more dense the optical memory,” Ndao said.
Hardware Integration Challenges Facing Future Memory Devices
The team is exploring optical structures capable of concentrating light into progressively smaller regions. These efforts are aimed at understanding how precisely engineered light can manipulate magnetism at extremely small scales. Provided that the remaining technical hurdles can be successfully surmounted, this strategy could pave the way for a novel class of dense, miniaturized memory systems capable of recording digital data at vastly accelerated rates.
