| 摘要 |
PURPOSE:To perform the remote control of a repeater output level in the APC operation of an optical repeater by extracting a low frequency signal on which amplitude modulation is applied with a corresponding optical repeater, respectively, and controlling the degree of amplification of the optical repeater based on the information of the degree of modulation of an extracted low frequency signal. CONSTITUTION:Amplitude-modulated main transmission signal light SL1 is amplified with the optical repeaters 15a-15n that are optical amplifiers in the middle way of transmission on the optical fibers 14a-14n on an optical transmission line at every transmission. Part of the light is branched with optical beam splitters 16a-16n, and the level of the low frequency signal is detected with APC control circuits 17a-17n consisting of an O/E converter, a filter, a level comparator, and an amplifier current source. Thereby, the gains of the optical repeaters 15a-15n that are the optical amplifiers are controlled so that their levels can be kept constant. |
