PURPOSE: To easily handle the input output of two-dimensional picture information by connecting a light emitting element for input arranged to a two-dimensional array and a light receiving element for output arranged to the two-dimensional array with an optical fiber coupling circuit.

CONSTITUTION: A laser diode (LD) to receive an input signal is two- dimensionally arranged, an LD array 5 is formed, a photodiode (PD) to output an output signal is two-dimensionally arranged and a PD array 7 is formed. The array corresponding to the LD and the PD is combined by optical fiber coupling circuits 6 and 6' and 2-channel constitution is obtained. The output signal of the PD is threshold-processed by a threshold circuit 8 and fed back to the LD. Thus, a light associative memory to facilitate the handling of the two-dimensional picture information can be constituted.