METHOD FOR REALIZING OPTICAL BISTABLE FUNCTION AND OPTICAL BISTABLE FUNCTION ELEMENT

摘要

PURPOSE:To provide a vertical oscillating semiconductor laser capable of operating bistably and having both light amplifying effect and rapid switching properties, by operating the laser with its active layer excited at a slightly lower level than the oscillating threshold value. CONSTITUTION:On the principal face of a semiconductor substrate 4, there are provided a lower reflector 3, an active layer 2 and an upper reflector 1 sequentially one on another to produce a vertical oscillating semiconductor laser, The vertical oscillating semiconductor laser thus produced is operated with its active layer 2 excited at a slightly lower level than the oscillating threshold value. The oscillating conditions of the laser in operation are reversibly controlled by inputting light from the outside of the laser. Thereby, high refractive index layers in the upper reflector 1 are excited and the absorption factor to laser light is decreased. Loss of an optical resonator is also decreased equivalently and the laser can be shifted to oscillating state. Once the laser has entered into the oscillating state, it can keep the high refractive index layers in the upper reflector 1 excited by its own laser light and can continue oscillation if external exciting light is removed.