| 摘要 |
PURPOSE:To reduce photodetection loss and return reflected light by arranging a photodetecting element that its photodetection surface is not perpendicular, but at a specific angle to the optical axis of a lens having a limited pitch range and providing a stopper for gap formation at the light incidence side of a lens insertion hole. CONSTITUTION:A convergent rod lens 17 with 0.35-0.45 pitch is inserted into the lens insertion hole 18 and fixed at the position of a gap stopper 15 with an adhesive. The package 13 of the photodetecting element 11 is fixed with an adhesive in an insertion hole 19 for the photodetecting element package which slants at 9.5-20 deg. to the axis of the lens insertion hole so that the photodetection surface faces the light output side of the lens 17. The gap forming stopper 15 not only specifies the arrangement position of the converging rod lens 17, but also forms a gap between the light incidence surface 20 of the lens 17 and the surface of an inserted optical fiber. Consequently, reflected light from the photodetecting element photodetection surface is prevented from returning to the optical fiber through the lens, and reflected light from the rod lens is also prevented from propagating in the optical fiber. |
