| 摘要 |
PURPOSE:To enable the very period of a diffraction grating to change optionally through an external control by a method wherein a coherent monochromic light is made incident on both the ends of an active layer to generate a standing wave so as to make the active layer function as a diffraction grating. CONSTITUTION:This element of a semiconductor laser is composed of a p-InP layer 2 of a clad layer, an InGaAsP layer 3 of an active layer, and an n-InP layer 4 of a clad layer all formed on a p-InP substrate 1. External light rays, incident on both the ends of the active layer 3 of a high refractive index through the n-type clad layer 4, travel through the active layer as an optical waveguide in directions opposite to each other, so that a standing wave is generated. Therefore, the energy applied to the active layer 3 is made to grow periodic and a carrier density inside the active layer 3 varies in the same period, and consequently the active layer 3 serves as a diffraction grating toward oscillating laser rays of a semiconductor laser. By these processes, the wavelength of oscillating laser rays can be controlled by varying that of external laser rays. |
