| 摘要 |
PROBLEM TO BE SOLVED: To amplify a wavelength multiplexed light under a flat gain profile, even in a 1580 nm band. SOLUTION: A pumping laser 12 pumps a laser beam with a prescribed luminous intensity, so that an optical amplifier employing an EDF 11 can obtain a fixed flat gain. Optical demultiplexers 21, 31 branch an input output signal light to an EDFA by about several percentages, a DMUX filter 22 branches the demultiplexed input light, a monitor circuit 23 monitors the presence of each channel signal and the luminous intensity via light receiving elements 24 and transmits the number of channels and the luminous intensity information to an arithmetic circuit 33. A light-receiving element 32 measures the intensity of the output light and delivers the information to the arithmetic circuit 33. The arithmetic circuit 33 decides attenuation depending on a change in the number of channels of the input output signal light and its luminous intensity, and allows a variable light attenuator 35 to cause the output signal of the EDF 11 to attenuate in batch via a drive circuit 34. |
