| 摘要 |
PURPOSE:To eliminate the deterioration of a diffraction grating due to meltback at the time of crystal growth and to contrive to obtain the diffraction grating of good quality by a method wherein a semiconductor laser is provided with a clad layer of a flat structure, wherein mixed crystal parts and superlattice structure parts are regularly repeated, and this clad layer is utilized as the diffraction grating. CONSTITUTION:GaAs-AlAs superlattice structure parts 2A and AlGaAs mixed crystal parts 2B, made by Si ion implantation in a GaAs-AlAs superlattice structure at a pitch of about 3000Angstrom and by an annealing, are provided on an N-type GaAs substrate 1. By turning the GaAs-AlAs superlattice structure into a mixed crystal at a pitch of about 3000Angstrom , the periodic change of the refractive index can be obtained. For example, if the superlattice structure is turned into a mixed crystal and becomes an Al0.53Ga0.47As superlattice structure, the refractive index becomes smaller by 0.2. A clad layer having the periodic change of a refractive index at a pitch of 3000Angstrom or thereabouts can be used as a tertiary diffraction grating to light to ooze out to a guide layer 3 from an active layer 4. |
