PURPOSE: To prevent the generation of return light generated by re-incidence to an optical fiber of reflected light by a photodetector, by placing a reference plane of the optical fiber by inclining it to a reference plane of the photodetector.
CONSTITUTION: An optical fiber 1 is placed so that an optical axis A becomes parallel to a photodetecting surface 4 of a photodetector 3 [shown in the figure (a)] and also an optical fiber reference plane, namely, a plane AP passing through the optical axis A and vertical to the end face is inclined at an angle θ to a photodetector reference plane, namely, a plane BP parallel to the optical axis A and vertical to the photodetecting surface 4 [shown in the figure (c)]. In this regard, the angle θ is made larger than the maximum emitting angle of light to the optical fiber reference plane AP.
OKIYAMA TADASHI
HORIMATSU TETSUO
