SEMICONDUCTOR LASER

PURPOSE:To obtain a semiconductor laser having optical switching characteristics, a current narrowing high efficiency by combining multilayer films composed of predetermined thickness of quantum wells, setting the thickness of a semiconductor contact layer of an output side to a special value, and specifying compound of the semiconductor layer. CONSTITUTION:When a current flows forward between electrodes 111 and 101 and a light of a wavelength corresponding to a quantum level difference of a quantum well layer 107 is irradiated, lights having different wavelengths are output from quantum levels n=1 and n=2. In this case, a resonator is formed between upper and lower multilayer film mirrors, and a laser oscillation from the quantum level n=2 of high reflectivity occurs. When a light of a wavelength corresponding to n=1 is externally input in this state, the level of the laser oscillation is shifted from n=2 to n=1, and optical switching can be externally performed. Further, since leakage of injected current to the high resistance buried layer does not occur, current narrowing is performed. Further, an effective light confinement is performed by a rib waveguide structure using a ZnS0.06Se0.94 layer.