Photodetector and optical receiver

摘要

An optical receiver is provided with an optical-signal-receiving section and a controlling section. The optical-signal-receiving section incorporates a photodetector. The photodetector has an APD. Through a passivation film, a photoconductor is placed on a portion of a surface of the APD which remains unoccupied by an optical-signal-receiving area of the APD. When this structure is employed, the signal for controlling the avalanche multiplication factor of the APD can be obtained from the photoconductor. Consequently, the signal can be obtained with a simple structure. Furthermore, the photoconductor has a good linearity of the output current even to a weak lightwave. As a result, the output current I for controlling the avalanche multiplication factor of the APD can be obtained with high accuracy.