| 摘要 |
<P>PROBLEM TO BE SOLVED: To suppress a transient response when an input level to an optical amplifier is fluctuated. <P>SOLUTION: Supposing that a signal light 32 received by an optical multiplexer 13 is shut off by a line fault or the like, then an EDF 18 amplifies only an Add signal light 33. In this case, since a gain of the EDF 18 is low, an input level of the wavelength λk is increased in advance. Thus, since the EDF 18 carries out gain constant control, the input level set originally high is amplified by a constant gain, resulting in that an output level increases more than that before occurrence of the fault. When variations in the signal light 32 are detected, a level adjustment unit 15 is controlled so that the level of the Add signal light 33 amplified by the EDF 18 is constant. Thus, the transient response of the EDF 18 is suppressed. <P>COPYRIGHT: (C)2007,JPO&INPIT |
