| 摘要 |
PURPOSE:To provide a photodetector in which detection accuracy due to interference by an undesired reflected light is not deteriorated with respect to an optical device employing a light source of a narrow spectrum. CONSTITUTION:An optical signal which is branched by a 12dB photocoupler 101 and attenuated by 10dB by an optical attenuator 105 is reflected partly for its optical power when a 2nd optical connector 108 is disconnected or the like. However, since the reflected return light is attenuated further by 10dB by passing through the optical attenuator 105 again, the light is considerably attenuated when the light is inputted to an optical-to-electrical transducer section 102 via the 12dB photocoupler 101 or the like and mutual interference effect with the reflection return light used to discriminate the connection state of the 1st optical connector 107 or the like is small and a change in the optical power due to interference is not caused. Thus, the electric signal level in the optical-to-electrical transducer section 102 is stabilized and a comparison discrimination section 109 discriminaties accurately the connection state of the 1st optical connector or the like. |
