| 摘要 |
PROBLEM TO BE SOLVED: To keep the output from the optical amplifier constant independently of a multiplexed signal number in the optical amplifier amplifying a signal light subject to wavelength multiplexing. SOLUTION: The amplifier is provided with an optical amplifier 1 amplifying a multiplexed signal light to provide an output of an amplified signal light, 1st and 2nd optical demultiplexers 2, 3 demultiplexing part of the amplified signal light and providing respectively 1st and 2nd demultiplexed signal lights, the number of multiplexed signal lights is detected from the 2nd demultiplexed signal light by a wavelength selection section and a reference value is set corresponding thereto and the reference value and the level of the 1st demultiplexed signal light are compared to control the amplifier 1. The wavelength selection section is provided with an optical switch 6 applying on/off control to the 2nd demultiplexed signal by a pulse signal and with a fiber grating 8 which reflects a light of each one wavelength with respect to a plurality of wavelength bands selectively and provides an output of a selected signal light from its input terminal and the both are connected by an optical circulator 7. The signal light having a peak value is detected from the multiplexed signal light and feedback control may be conducted based on the peak value. |
