Artificial optoelectronic spiking neuron based on a resonant tunnelling diode coupled to a vertical cavity surface emitting laser

Abstract

Excitable optoelectronic devices represent one of the key building blocks for implementation of artificial spiking neurons in neuromorphic (brain-inspired) photonic systems. This work introduces and experimentally investigates an opto-electro-optical (O/E/O) artificial neuron built with a resonant tunnelling diode (RTD) coupled to a photodetector as a receiver and a vertical cavity surface emitting laser as a transmitter. We demonstrate a well-defined excitability threshold, above which the neuron produces optical spiking responses with characteristic neural-like refractory period. We utilise its fan-in capability to perform in-device coincidence detection (logical AND) and exclusive logical OR (XOR) tasks. These results provide first experimental validation of deterministic triggering and tasks in an RTD-based spiking optoelectronic neuron with both input and output optical (I/O) terminals. Furthermore, we also investigate in simulation the prospects of the proposed system for nanophotonic implementation in a monolithic design combining a nanoscale RTD element and a nanolaser; therefore demonstrating the potential of integrated RTD-based excitable nodes for low footprint, high-speed optoelectronic spiking neurons in future neuromorphic photonic hardware.

Brain-inspired nanophotonic spike computing: challenges and prospects

“…CC BY 4.0. ), and (f) demonstration of in-device coincidence detection (logical AND), (right), and exclusive logical OR (XOR) tasks (left) (Reproduced from [73]. CC BY 4.0.).…”

Tunable presynaptic weighting in optoelectronic spiking neurons built with laser-coupled resonant tunneling diodes

“…In recent decades, research in artificial intelligence (AI) has experienced significant 39 advances driven by the rapid expansion of amounts of available data and cheaper, readily rendering them as a viable solution for controllable spiking generators [22], [31]- [34].…”

“…Spike amplitude tuning in synaptic links underpins the weighting 93 functionality, which is key to information processing in spiking neural networks. As The RTD device (with a 3 µm radius circular mesa) is fabricated by metalorganic 131 vapour-phase epitaxy (MOVPE) on a semi-insulating InP substrate, containing a core 132 1.7 nm AlAs/5.7 nm InGaAs/1.7 nm AlAs DBQW structure surrounded by highly doped As the core element of the PRL spiking neuromorphic system, the RTD provides 162 excitability and spiking functionality for the artificial neuron [22]. To trigger the spikes 163 in the PRL, the CW light from the 1310 nm tuneable laser is intensity-modulated via a 164 fiber-coupled MZM (JDS Uniphase).…”

“…where the threshold for spike firing is marked as a dashed line. Since the RTD is biased 175 at an operation point close enough to the NDC region (here V RT D = 870 mV), pulses 176 with sufficient (super-threshold) amplitude can elicit spiking responses, while pulses 177 with sub-threshold amplitude do not trigger a spike in the RTD and the system remain 178 quiescent [22]. during which it cannot respond to any other incoming stimulus.…”

“…during which it cannot respond to any other incoming stimulus. This is referred to 182 as the refractory (lethargic) period [22]. To investigate this behavior, the input signal 183 is designed with a series of doublets where the interval within each doublet gradually…”