| 摘要 |
<p>A gain waveguide type semiconductor laser (10) oscillating visible light has an N type GaAs substrate (12) of, and a double-heterostructure provided above the substrate to include an InGap active layer (20), and first and second cladding layers (16, 18) sandwiching the active layer (20). The first cladding layer (18) consists of N type InGaA l P, whereas the second cladding layer (18) consists of P type InGaA l P. A P type InGaP layer (22) is formed as an intermediate band-gap layer on the second cladding layer (18). An N type GaAs current-blocking layer (24) is formed on the intermediate band-gap layer (22), and has an elongated waveguide opening (26). A P type GaAs contact layer (30) is formed to cover the current-blocking layer (24) and the opening (26). The intermediate band-gap layer (22) has a carrier concentration, in a layer portion (28a) being in contact with the opening (26), high enough to cause a current injected in the oscillation mode to concentrate on the layer portion (28a) and has a carrier density, in the remaining layer portion, low enough to suppress or prevent the injected current from spreading thereinto. The layer portion (28a) may be formed by additionally doping a selected impurity into the intermediate gap layer (22) by using a presently available impurity diffusion/injection technique.</p> |
