Re-writable DVDs and CDs save data using a material called "GST " -- an alloy made from germanium, tellurium and antimony -- that changes its structure when hit by a laser. The UK and German team built a chip using "waveguide" technology that directs light through channels etched into a silicon-nitride material. The chip was coated with nanoscale GST, then blasted by a high-intensity laser through the waveguide channels. That changed the GST from a consistent crystalline structure into an amorphous blob, which was detected by another low-intensity laser and read out as data.
A nano-photonics chip developed by IBM Research
The GST transforms back to a crystalline state when hit with another high-intensity shot, making for a true rewritable device. By varying the intensity and wavelength of the lasers, the team was even able to store up to 8 bits of data in a single location, a big improvement over binary electronic devices.
While the research is promising, there's still a lot of work before commercial, light based devices appear. For starters, the chips will have to be hundreds of times smaller before they can compete with flash storage. However, the prototype chip is on par with its electronic counterpart for speed and power consumption, and the technology already exists to make it commercially feasible, according to the team. If paired with photonic logic chips, it could eventually result in computers that are up to 100 times faster than the one you're using now.