| 摘要 |
PURPOSE:To enable the reduction of noise by multimodes and to contrive to facilitate the design by obtaining the reduction in astigmatic difference and the symmetry and stability of a far field pattern by a method wherein the titled device is enabled to have both properties of gain guide type and index guide type. CONSTITUTION:A current restricting region layer 17 serving as a photo absorbing layer having a smaller energy gap than a clad layer 15 and having the conductivity type different from that of the layer 15 is formed in the layer 15, a current concentration part of stripe form being formed by providing a lack part 17a of stripe form at the center of the layer 17 and thus constructing an internal stripe structure. The width W of the part 17a is selected at 3-5mum. Further, the difference in effective refractive index DELTAn(n-nS) when the refractive index of the part corresponding to the part 17a 9s (n), and the refractive index nS under the layer 17 is nS is 8X10<-4>-2X10<-3>. |
