PURPOSE: To increase a product sum calculating speed and to perform integration by enabling a light emitting element in three-terminal structure to serve as both a light emitting means and an optical shutter means, and performing modulation for light emission by varying a voltage applied to a striped collector area and modulation for weighting by varying the amount of a current injected into an emitter area.

CONSTITUTION: A base electrode 4 is used as a common electrode, N voltage sources capable of voltage modulation are connected to N collector electrodes 3, and N×M current sources capable of current modulation are connected to N×M emitter electrodes 5. At this time, the quantity of light emission of the light emitting element 10 is proportional to the reciprocal of a light emission recoupling time and proportional to the amount of the injected current. The weighting of product sum arithmetic is controlled with the amount of current injection from the emitters 5 and the input vector of the product sum arithmetic is made to correspond to an input voltage to striped collector electrodes 3 which are arrayed. Consequently, the product sum arithmetic is speeded up and the integration is performed.