DYNAMIC OPTICAL NEUROCHIP USING VARIABLE-SENSITIVITY PHOTODIODES

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 optical cross talk, higher processing speed, and realization of analog synaptic weights. Also, experimental results of the VSPD array using metal-semiconductor-metal structure are shown. The results of the computer simulation using this chip as a learning element show that the unwanted effect of the optical cross talk on the recognition rate can be alleviated by the learning capability of the chip. It is also found that the theoretical maximum density is approximately 2000 neurons/cm2 for the backpropagation model.