| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an inexpensive optical amplifier where a flat output wavelength characteristic and sufficient NF can be obtained irrespective of a signal light input level per wavelength of WDM light and the number of wavelengths. <P>SOLUTION: The optical amplifier is provided with first and second optical amplification parts 10 and 20 connected in series between an input port IN and an output port OUT, a first variable optical attenuator 31 arranged in a prestage of the first optical amplification part 10, a second variable optical attenuator 32 arranged between the first and second optical amplification parts 10 and 20, an optical amplification control part 40 controlling the first and second optical amplification parts 10 and 20 and an optical attenuation control part 50 controlling the first and second variable optical attenuators 31 and 32. The optical amplification control part 40 controls the respective optical amplification parts so that a gain of the whole optical amplifier becomes constant. The optical attenuation control part 50 controls an attenuation amount of the respective variable optical attenuators so that monitor values of output power of the respective variable optical attenuators are approximated to the same values by making that a value of a sum of the attenuation amounts of the respective variable optical attenuators, which are decided in accordance with signal light input power per wavelength of WDM light, is held constant as a condition. <P>COPYRIGHT: (C)2008,JPO&INPIT |
