On-chip photonic synapses herald new age of computing

Researchers at Oxford, Münster and Exeter universities have been working together on photonic microchips that mimic the way the brain’s synapses operate. The use of phase-change materials (PCMs), as used in rewritable optical discs for example, was key to creating the integrated photonic circuits that deliver a biological-like synaptic response. Impressively, photonic synapses can operate at speeds a thousand times faster than those of the human brain.

It is explained that in organic life forms “neuronal synapses outnumber neurons by many orders of magnitude” [approx 10,000 to 1].Thus, to make a powerful neuromorphic computer inspired by brains, scientists should replicate this structure. The new hardware which uses photonics to replicate a synapse, is considered to be a landmark breakthrough in the quest for the “holy grail” of computing.

Team leader, Professor Harish Bhaskaran from Oxford University said that “The development of computers that work more like the human brain has been a holy grail of scientists for decades. Via a network of neurons and synapses the brain can process and store vast amounts of information simultaneously, using only a few tens of Watts of power. Conventional computers can’t come close to this sort of performance.”

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Professor David Wright, co-author from the University of Exeter, added “Electronic computers are relatively slow, and the faster we make them the more they consume. Conventional computers are also pretty ‘dumb,’ with none of the in-built learning and parallel processing capabilities of the human brain. We tackle both of these issues here — not only by developing not only new brain-like computer architectures, but also by working in the optical domain to leverage the huge speed and power advantages of the upcoming silicon photonics revolution.”

The hardware synapse designed by the team is implemented entirely in the optical domain via a photonic integrated-circuit approach. The design eliminates bandwidth concerns and electrical interconnect power losses. A further great benefit of the optical design is the enabling of systems with a continuously variable synaptic plasticity, resembling the true analogue nature of biological synapses.

An abstract and the full research paper entitled ‘On-chip photonic synapse’ is available via the Science Advances journal.