an optical memory circuit comprises two photodetectors , and an intermediate signal conductor for connecting the two photodetectors , wherein the two photodetectors and the signal conductor are connected in series in a closed circuit , wherein each of the photodetectors comprises two spaced schottky electrodes symmetrically disposed on a semiconductor substrate and the signal conductor has a capacitance with a time constant of a potential of the signal conductor such that charges are stored in the signal conductor when an optical write signal is incident on one photodetector and stored charges are released from the signal conductor when an optical read signal is incident on the other photodetector .