| 摘要 |
PROBLEM TO BE SOLVED: To protect the device from the input of optical surge in the optical signal receiving device in an optical communication system including a light amplifier. SOLUTION: The optical signal receiving device in the optical communiation system provided with the light amplifier is provided with a resistor 3 as a load impedance connected between power source terminals in series, a photodetector 1 and an output resistor 2. An output terminal 4 is connected to a contact point between the photodetector 1 and the output resistor 2. When the resistance value of the resistor 3 is set to be R, power voltage to be Vd, limit current to be IL, the impression voltage of the photodetector 1 at normal time to be VO, current at that time to be IO and built-in voltage to be Vbi , the relation expression of R=(Vbi +VO)/(IL-IO). Vd=(IO.Vbi +IL.VO)/(IL-IO) are satisfied. |
