| 摘要 |
PURPOSE:To reduce the threshold value by a method wherein a region provided with grating is lengthened enough to obtain sufficient amount of feedback, then an active layer is restricted to a part thereof in the optical direction and made transparent to laser oscillated light at regions other than that part. CONSTITUTION:In the section of the surface parallel with the direction of advancement of laser light of DFB type semiconductor laser, an N-Ga1-xAlxAs clad layer 2, Ga1-yAlyAs active layer 3, and a P-Ga1-zAlzAs clad layer 4 are grown on an N-GaAs substrate 1, and the periodic grating 10 is formed by a chemical etching. Thereafter, a P-Ga1-xAlxAs clad layer 5 and a P-GaAs cap layer 6 are grown, and next Zn is selectively diffused into a region 9 by leaving regions 11 and 11. Afterwards, an N-side electrode 8 and a P-side electrode 7 are formed. The band gap becomes small at the Zn diffused region, and the active layer 3 becomes transparent to laser light at the regions 11 and 11. |
