COMPUTING AT THE SPEED OF LIGHT
Think the latest flash drives are fast? Think again. Researchers have created the first optical-only chip that can permanently store data, a development that could in time enable the production of storage devices that would make SSDs look like they were from the Stone Age.
The research team solved the problem of permanent storage using a familiar – albeit even old-fashioned lightbased medium – DVDs. Re-writable DVDs and CDs save data using GST, an alloy made from germanium, tellurium and antimony. GST changes structure when hit by a laser, and the researchers built a chip using waveguide technology that directs light through channels etched into a silicon-nitride material.
The chip itself was coated with nanoscale GST, then blasted by a high-intensity laser through the waveguide channels. This altered the GST’s consistent crystalline structure and made it more akin to an amorphous blob, a change that was then detected by another low-intensity laser and interpreted as data.
The process is cyclical, and when hit by another highintensity laser, the GST reverts to its crystalline state. By varying the intensity and wavelength of the lasers, the team was able to control the extent of each GST patch that was either crystalline or amorphous. This enabled them to store data in up to eight different combinations, a huge boost in the amount of data that each spot can store.
While you shouldn’t expect light-based drives any time soon, the team says that the technology already exists to make these optical chips commercially feasible. They even have applications beyond storage – if paired with photonic logic chips, we could one day see computers up to 100 times faster than modern machines.