| 摘要 |
PURPOSE: To prevent effect of an optical surge from being imparted to a post- stage by providing an optical amplifier part and an optical output control circuit for monitoring an optical output of an optical demultiplexer and lowering the gain of the optical amplifier part when a surge optical input is detected within a prescribed time. CONSTITUTION: The optical input is divided into two parts by the demultiplexer 1, and one side is fed to the optical output control circuit 4 and the other side is fed to the optical amplifier part 3 after being delayed by a prescribed time with a dispersion compensation fiber 2. While the optical input is delayed with the dispersion compensation fiber 2, the optical output control circuit 4 monitors the optical output from the demultiplexer 1, and controls the optical amplifier part 3 to lower its gain when it detects the input of the optical surge. Further, by connecting the dispersion compensation fiber 2 to the optical amplifier part 3, a compensation function for transmission quality deterioration due to transmission line dispersion in a transmission line fiber in which a transmission wavelength does not match with a zero dispersion wavelength is provided. |
