摘要 |
In an optical amplifier for wavelength-multiplexing transmission of this invention, signals of a plurality of wavelengths in a 1.55-mum wavelength band, which is input to an input terminal, sequentially passes through an optical isolator and optical coupler, and is input to an amplification optical fiber to be amplified. The signals amplified by and output from the amplification optical fiber sequentially passes through an optical isolator, optical coupler, optical isolator, and optical coupler, and is input to a further amplification optical fiber to be amplified. The signals amplified by and output from the further amplification optical fiber sequentially passes through an optical coupler, optical isolator, and optical coupler and is output from an output terminal. Each of an input-side optical amplifier and output-side optical amplifier performs constant output control.
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