| 摘要 |
PURPOSE:To stabilize signal receiving sensitivity by reflecting the output light of a photocoupler by a reflecting mirror part formed by molding the side face of a semiconductor substrate to a slant face and receiving said light by photodetectors provided on the semiconductor substrate. CONSTITUTION:The end face on one side in the longitudinal direction of the semiconductor substrate 1 is formed aslant and a metallic film 5 is provided on the slant end face to constitute the reflecting mirror part 3. The signal light and locally emitted light from optical fibers 13, 14 are synthesized by the photocoupler 8 and are then approximately equally divided. The divided light rays are detected by the photodetectors 4, 4 via the mirror part 3. The optical distance from the output port of the photocoupler 8 to the photodetector 4 is determined by the extended length of waveguide 2, 2 and the reflection position of the mirror part 3 and, therefore, the deviation of the phases of the synthesized light branched to the two rays on the photodetection surface is prevented if the waveguides 2, 2 are so formed that the optical distances between both coincide at the time of forming the waveguides on the substrate 1. The decrease in the electrical outputs taken out of the photodetectors 4, 4 is thus prevented. The good signal receiving sensitivity is thereby obtd. |
