Scientists, for quite some time now, have been advocating the use of “light” based computing and memory chips that could revolutionize the electronics world as we know it. Now a team of researchers led by a nanoengineering expert at the University of Oxford, Harish Bhaskaran, has claimed to have created the first optical memory chip that would permanently store data.
Earlier, the optical memory chip designs had failed due to its volatile nature. But the researchers’ team had bypassed the problem using an already available and widely used storage devices-CDs and DVDs. A thin layer of GST, an alloy of germanium, antimony, and tellurium is used on these devices to save data.
GST has a unique property of changing its atomic structure from the ordered crystalline to amorphous state when hit by laser pulses. Now light is reflected differently by both these atomic structures which is later on detected by low-intensity light as it tracks the difference on the GST surface, and that’s how the data is read back.
The researchers’ team build a chip using waveguide technology that channels the optical pulses on a silicon nitride device. After that, they tested the chip by coating it with a nanolayer of GST and shot high-intensity laser pulses at it. As the GST molecules changed their atomic structure from crystalline to amorphous, the low-intensity laser pulses reverted the process back i.e. from amorphous to ordered crystalline, making it a potential memory and rewritable device.
But what accounts as an achievement is that the scientists were able to store multiple bits (information) simultaneously as they sent multiple wavelengths of light through the waveguide. This means they could read and write multiple bits simultaneously, a property that is limited in the conventional storage devices.
As the team varied the wavelengths and intensity of the laser, they were able to store up to 8 bits of data at a single spot.
The experiment shows that the optical memory chips could make our computers 100 times faster with a more advanced photonic memory and better waveguide technology. And the pace at which the research is continuing, that future does not seem too far away.
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