| 摘要 |
PROBLEM TO BE SOLVED: To reduce light loss inside a node and to suppress exciting light output to the rear part of an EDFA gate switch. SOLUTION: Signal light outputted to an optical transmission line 131 is outputted to a gate type light amplifier 51 by the demultiplexing function of a wavelength multiplexed light branching 151. The signal light light-amplified in the gate type light amplifier 51 is inputted through an optical isolator 91 to the wavelength multiplexed light branching 152, outputted to the optical transmission line 132 by the multiplexing function, then multiplexed with other wavelength light in an optical demultiplexer/multiplexer 410 and outputted to the optical transmission line 120. The signal light from the transmission line 131 is branched by optical branching 31 and inputted to an optical receiver 71. For the insertion of optical signals, the gate type light amplifier 51 is turned to an OFF state and the signal light outputted from an optical transmitter 81 is connected through the light branching 41 to the optical transmission line 132 and outputted through the optical demultiplexer/multiplexer 410 to the optical transmission line 120. Since the wavelength multiplexed light branching 151-154 demultiplex and multiplex the light of different wavelengths with low loss, the loss is lowered by 5 dB or more compared to the case of using the light branching of one-to-one correspondence. |
