The world’s first entirely light-based memory chip to store data permanently has been developed by material scientists at Oxford University.
The device makes use of materials used in CDs and DVDs, and it could help dramatically improve the speed of modern computing.
Today’s computers are held back by the relatively slow transmission of electronic data between the processor and the memory. There’s no point using faster processors if the limiting factor is the shuttling of information to-and-from the memory. The researchers think using light can significantly speed this up.
Simply bridging the processor-memory gap with photons isn’t efficient, though, because of the need to convert them back into electronic signals at each end. Instead, memory and processing capabilities would need be light-based too. Researchers have tried to create this kind of photonic memory before, but the results have always been volatile, requiring power in order to store data. For many applications — such as computer disk drives — it’s essential to be able to store data indefinitely, with or without power.
Now, an international team of researchers including researchers from Oxford University has produced the world’s first all-photonic nonvolatile memory chip. The new device uses the phase-change material Ge2Sb2Te5 (GST) — the same as that used in rewritable CDs and DVDs — to store data. This material can be made to assume an amorphous state, like glass, or a crystalline state, like a metal, by using either electrical or optical pulses.
The team has shown that intense pulses of light sent through the waveguide can carefully change the state of the GST. An intense pulse causes it to momentarily melt and quickly cool, causing it to assume an amorphous structure; a slightly less-intense pulse can put it into an crystalline state.
Later, when light with much lower intensity is sent through the waveguide, the difference in the state of the GST affects how much light is transmitted. The team can measure that difference to identify its state — and in turn read off the presence of information in the device as a 1 or 0
By sending different wavelengths of light through the waveguide at the same time — a technique referred to as wavelength multiplexing — the team also showed that they could use a single pulse to write and read to the memory at the same time.
Now, the team is working on a number of projects that aim to make use of the new technology. They’re particularly interested in developing a new kind of electro-optical interconnect, which will allow the memory chips to directly interface with other components using light, rather than electrical signals.
Post time: Nov-12-2017