| 摘要 |
PURPOSE:To easily couple with an external optical fiber or the like and to obtain the high coupling efficiency at any wavelength by a method wherein two or more quantum well active layers, which are laminated between interfaces in a propagation direction of a laser beam inside a single resonator via a barrier layer and whose structure of an energy level is different, and a diffraction grating as a reflector on one side of a resonator and installed so that an electric current can be impressed independently of each other. CONSTITUTION:Quantum well active layers 14a, 14b sandwiching a barrier layer 15 are composed of AlxGa1-xAs of a material of the same constituents; their thickness is different from each other; discrete accordingly, the discrete energy levels are different at the quantum well active layer 14a and the quantum well active layer 14b. If a function of select any wavelength is available, a laser is oscillated at a wavelength which corresponds to a range between these prescribed energy levels. In this semiconductor layer, a diffraction grating 19 as a reflector on one side of a resonator is installed at a part of an interface between a light waveguide layer 13 and a clad layer 12; accordingly, the laser is oscillated by the light of the prescribed energy level which corresponds to the wavelength satisfying Bragg's reflection condiction of this diffraction grating 19. If an electric current is impressed on this diffraction grating between a p-electrode 21b and an n-electrode 20, a length of a cycle of the diffraction grating 19 is changed effectively with reference to the light. |
