Optoelectronic Memristor Model for Optical Synaptic Circuit of Spiking Neural Networks

Optoelectronic memristors are suitable candidates for hardware implementation of optical synapses in spiking neural networks (SNNs), thanks to their electrical and optical characteristics. To study the feasibility of memristor-based optical synapses in SNNs, a behavior model for optoelectronic memristors is proposed in this paper, including electrical programming modeling and photocurrent read modeling. Based on the model, the behavior of a molecular ferroelectric (MF)/semiconductor interfacial memristor is simulated. This paper also proposes an optical synaptic circuit for trace-based spike-timing-dependent plasticity (STDP) learning rule. The electrical characteristics of the memristor are explored and exploited to emulate the trace in the pairwise nearest-neighbor STDP, while the optical characteristics are utilized for non-destructive readout and weight calculation. Synaptic-level simulation results show a 99.96% correlation coefficient (CC) and a 1.91% relative root mean square error (RRMSE) in the weight approximate computation. Extending the simulation to the network level, the optoelectronic memristor-based unsupervised STDP learning system can achieve a 92.07± 0.64% accuracy on the MNIST benchmark.