| 摘要 |
PROBLEM TO BE SOLVED: To attain relay transmission without attenuating an optical signal over a wide band by arranging an optical filter making a pass band gain characteristic of an optical amplifier flat so as to make an accumulated gain characteristic of the optical amplifier flat. SOLUTION: A plurality of optical amplifiers 1 are arranged between a wavelength multiplex luminous signal transmitter 2 and a wavelength division luminous signal receiver 3 and an optical filter 4 is arranged to each of a prescribed number of optical amplifiers. The optical filter 4 is desired to be arranged to each of 10 to 30 optical amplifiers 1. When the number of the optical amplifiers 1 is less than 10, much gain difference is not caused in the pass band and the matching with the filter is not taken, then an output is affected by the filter characteristic. On the other hand, when the number of the optical amplifiers 1 exceeds 30, it is difficult to configure the optical filter 4 to compensate it. Even if it is possible to configure the optical filter 4, it results in matching with a wavelength with less gain, undesirably accompanied by the increase in loss. |
