| 摘要 |
PROBLEM TO BE SOLVED: To lessen a module in size by a method wherein it is equipped with a first and a second projection edge connected to a first and a second projection optical waveguide respectively. SOLUTION: Signal light of 1.3μm band impinging on an impinging/projecting edge is guided to a PD of 1.3μm band through a Y-branching optical waveguide and photoelectrically converted, and electrical signals are taken out. At this point, signal light of 1.3μm band is attenuated enough in both the PD of 1.3μm band and a DFB-LD of 1.3μm band, so that it is not projected from the 1.55μm band signal light projecting rear edges of the optical waveguides. On the other hand, signal light of 1.55μm band is made to impinge on the impinging/projecting edge and therx branched off by the Y-branching optical waveguide into two parts, one is projected from the 1.55μm band signal light projecting rear edge of the optical waveguide passing through the DBF-LD of 1. 3μm band and a waveguide-type monitor PD, and the other is projected from the 1.55μm m band signal light projecting rear edge of the optical waveguide passing through the PD of 1.3μm band. That is, an optical semiconductor integrated circuit of this constitution itself has the function of a branching filter. These elements are all monolithically integrated on the semiconductor substrate. |
