| 摘要 |
PROBLEM TO BE SOLVED: To appropriately amplify an optical signal to be transmitted through an optical fiber cable by controlling the light amplification factor of an optical amplifying means which is obtained by decoding a received optical signal. SOLUTION: In demodulators 321 to 32n, the electric signal of a respectively corresponding modulation frequency is extracted, and the extracted electric signal is demodulated. Also, in a light amplification factor controller 121, a bandpass filter 152 extracts an electric signal of modulation frequency of any modulator 101 which is included in an electric signal inputted from a distributor 131 and outputs it to a power meter 151. Then, the power of the electric signal is measured, and a light amplification factor controller 150 decides the light amplification factor for an optical amplifier of an optical amplifying device 105 so that the power of an electric signal to be demodulated by, e.g. a demodulator 321 can be within an allowable range based on an inputted power measurement result signal and outputs a light amplification factor instruction signal S121 showing the decided light amplification factor to plural optical amplifying devices including the device 105. |
