| 摘要 |
PURPOSE:To obtain a distributed feedback semiconductor laser possessed of a required coupling constant by a method wherein a diffraction grating is formed, the depth of the grating is measured, and a layer which controls the semiconductor laser in coupling constant corresponding to the depth concerned is formed. CONSTITUTION:A P-type InP clad layer 2, an In0.58Ga0.42As0.9P0.1 active layer 3, and an N-type In0.82Ga0.18As0.4P0.6 optical waveguide layer 4 are successively formed on a P-type InP substrate 1. A deepish diffraction grating 5 is provided to the N-type In0.82Ga0.18As0.4P0.6 optical waveguide layer 4 through an interference exposure method so as to make its coupling constant larger than a required coupling constant K. Then, the depth of the diffraction grating 5 is measured, an N-type In0.82Ga0.18As0.4P0.6 coupling constant controlling layer 7 is formed so as to make the diffraction grating 5 adequate in depth to obtain the required coupling constant K, and furthermore an N-type InP clad layer (6) is grown. If the grown layer is different from an N-type InP clad layer 6 is refractive index, it is replaced, whereby a required coupling constant can be obtained the same as above. |
