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We report on a GaAs/AlGaAs optical neurochip based on a three-layered feed-forward model. The optical neurochip consists of a light-emitting diode array with 66 elements, a fixed interconnection matrix, and a photodiode array with 110 elements. The interconnection matrix is determined by the backpropagation learning rule with three quantized levels. There(More)
A novel type of photodetector called a variable-sensitivity photodetector has been developed for optical implementation of neural networks. It utilizes a metal-semiconductor-metal structure whose quantum efficiency can be modulated by an applied bias voltage. A linear dependence of the sensitivity on the bias voltage was obtained with the bipolar current(More)
An optical neurochip with learning capability and a memory function is reported for the first time, to our knowledge. The neurochip is a three-dimensional optoelectronic integrated circuit consisting of a light-emitting diode array and a variable-sensitivity photodetector array. The principle of operation and the fundamental characteristics of the neurochip(More)
A novel type of a dynamic optical neurochip that uses sensitivity-variable photodiodes (VSPD's) as variable interconnection weight elements is proposed and analyzed. The chip consists of the line-shaped light-emitting diode array and the VSPD matrix array. A monolithic integration of these arrays is presented. This dynamic chip has advantages such as less(More)
An optical associative neural network with a stochastic thresholding procedure has been demonstrated. The use of stochastic processing drastically improved the convergence rate into the correct global minima (recognition rate). The properties of undesirable spurious minima were also investigated. It was found that the spurious minima were represented as the(More)
A GaAs/AlGaAs optical synaptic interconnection device for neural networks is reported for the first time to our knowledge. This device consists of a light-emitting-diode array, an interconnection matrix, and a photodiode array, which are integrated into a hybrid-layered structure on a GaAs substrate. The device structure and characteristics are reported in(More)
A GaAs/AlGaAs optical synaptic interconnection device for neural networks is reported. It consists of a light-emitting-diode array, an interconnection matrix, and a photodiode array, which are integrated in a hybrid-layered structure on a GaAs substrate. The device structure and characteristics are reported. The fabricated device can simulate a 32-neuron(More)
A new architecture for optical implementation of large-scale neural networks is proposed. This architecture is based on a time-division-multiplexing technique, in which both the neuron state vector and the interconnection matrix are divided in the time domain. Computer simulation and experimental results for associative memories show the effectiveness in(More)