Optical fibers demonstrate brain-like computing

March 16, 2015

(Left) A biological neuron transmits information through electrical and chemical signals between neurons by propagation of action potentials through the axon and release of neurotransmitters at synapses, causing excitatory and inhibitory postsynaptic potentials (spikes) that propagate in the postsynaptic axon. (Right) The photonic axon and synapse transmit information with optical pulses that propagate along an optical fiber. Changes of light intensity create inhibitory or excitatory action potentials in the postsynaptic axon. (credit: Behrad Gholipour et al./Advanced Optical Materials)

UK and Singapore researchers have simulated neural networks and synapses in the brain using optical pulses as information carriers over fibers made from light-sensitive chalcogenide glass.

The research, published in Advanced Optical Materials, has the potential to allow faster and smarter optical neuromorphic (brain-like) computers capable of learning, the researchers say.

Compared to biological systems, today’s computers are “up to a billion times less efficient — simulating 5 seconds of brain activity takes 500 seconds and needs 1.4 MW of power,” they note.

The researchers, from the Optoelectronics Research Centre (ORC) at the University of Southampton, UK, and Centre for Disruptive Photonic Technologies (CDPT) at Nanyang Technological University (NTU), Singapore, developed a proof-of-concept system that demonstrated optical equivalents of brain functions. These include holding a neural resting state and simulating the changes in electrical activity in a nerve cell as it is stimulated.

The changing properties of the glass act as the varying electrical activity in a nerve cell, and light provides the stimulus to change these properties. This enables switching a light signal, the equivalent to a nerve cell firing.

The research paves the way for scalable brain-like computing systems that enable “photonic neurons” with ultrafast signal transmission speeds, higher bandwidth, and lower power consumption than their biological and electronic counterparts, including “non-Boolean computing and decision-making paradigms that mimic brain functionalities,” the researchers say.

The project, funded under Singapore’s Agency for Science, Technology and Research (A*STAR) Advanced Optics in Engineering programme, was conducted within The Photonics Institute (TPI), a recently established dual institute between NTU and the ORC.

Abstract of Amorphous Metal-Sulphide Microfibers Enable Photonic Synapses for Brain-Like Computing

In the pursuit of all-optical brain-like computing, optical axons and photonic synapses are demonstrated using metal-sulphide microfibers, which allow the generation and propagation of optical action potentials. This gives rise to an all-optical implementation of a number of interneuronal and intraneuronal communication protocols that underlie learning and cognition in the brain.