A new optical neuron device for all-optical neural networks

A new optical neuron device has been developed. The device can perform both summation and thresholding operations in optics, and consists of a PIN a-Si:H photoreceptor, aluminum neuron electrodes and a ferroelectric liquid crystal light modulator. The a-Si:H photoreceptor shows characteristics of an ideal quantum efficiency (η∼1) and a good linearity (γ∼1). The optical neuron device exhibits a response time of ∼30 µs for incident light power of 9 µW and a contrast ratio of 300:1. Using this neuron device, a lenslet array and a memory mask, an all-optical neural network has been constructed. The network demonstrates an associative memory function on purely optical parallel processing without any help from electric computation.