| 摘要 |
An optical repeater for transmitting wavelength division multiplexed signal light comprising an optical amplifier for optically amplifies a wavelength division multiplexed signal light and an optical output control circuit for controlling the optical output level constant used in a bi-directional wavelength division multiplexed signal light transmission is provided, which detects an optical input level to be input in one optical amplifier and, when the level fluctuates from a predetermined value, adjusts the level to a predetermined optical input level by branching a part of an amplified signal light to be output from the other party's optical amplifier and combines it to an input light to return it to the original optical level. The predetermined optical level is set such that a gain obtained when each signal light is optically amplified by the optical amplifier will be a predetermined gain. Especially, by selecting a gain without the wavelength reliance of a gain of the optical amplifier, it becomes possible to uniform the level of each signal light and conduct a stable optical amplification even if the level fluctuates. Even if a certain signal light among the wavelength multiplexed signal lights has broken line or its level fluctuates, the input level of the optical amplifier is maintained constant and signal light is optically amplified properly. <IMAGE> |
