| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical module which is increased in coupling efficiency on the whole and can suppress stray light. SOLUTION: In Fig., a clad is indicated by 11-3a. A Y-branch part 13-1a normally branches off into two waveguides, so a stray light is generated differently from a waveguide mode transmitted through one waveguide. In a PD (photo diode) 12-2a, on the other hand, an absorption layer 12-2a-1 is able to receive light even not in single mode and the light need not to be guided to the PD by a single-mode waveguide as an optical waveguide. A multi-mode optical waveguide 11-2a is arranged as one circuit of the Y-branch circuit 13-1a and a photodiode is arranged at its terminal. Further, when the optical waveguide is abruptly changed as the multi-mode optical waveguide, many modes of high order are generated and it becomes difficult to completely confine light, so it is constituted so that the waveguide width is gradually expanded to generate a mode of high order which can be propagated. COPYRIGHT: (C)2004,JPO |
