Abstract
Optical signal inverter and memory were demonstrated through a purely optical approach in a simple structure composed of a laser diode and an Er-doped YAG crystal. The intensity of an output laser transmitted through the Er: YAG was suddenly decreased by increasing the injection current to put the oscillation wavelength of the laser close to the central absorption peak of the Er: YAG at 787.6nm. In addition, the transmission of the Er: YAG versus injection current char-acteristics showed hysteresis and optical bistability. These effects were caused by the red shift and the hysteresis of the wavelength of the laser diode against the injection current. With the use of these effects, the optical signal inverter and memory were realized at a response time of 100ps.
