| 摘要 |
PROBLEM TO BE SOLVED: To flatten the amplification gain for each wavelength of input light signals with different wavelengths by providing a plurality of preset optical fiber amplifiers in series. SOLUTION: An input light signal from a multiplexer 72 is branched by a tap coupler 16, 99% of it is transmitted to optical amplification optical fibers 80 and 90 where erbium is added, and 1% is transmitted to a photodiode 28 and then is inputted to a control circuit 50. Also, a photodiode 38 applies an output light signal from a tap coupler 36 to the control circuit 50. On the other hand, diodes 60 and 30 for pumping laser allow excitation light with a specific wavelength to be passes through multiplexers 66 and 26 according to an operation current, amplifies a light signal with a short wavelength by an optical fiber 80, and amplifies a light signal with a long wavelength by an optical fiber 90. On the other hand, the flat gain spectrum of an input light signal that is applied to the laser diodes 60 and 30 by a specific program and is passed through two optical fiber amplifiers is maintained by the control circuit 50. |
