Optical transmission system and optical amplifying apparatus, optical amplifying unit, and optical coupler for the same

摘要

Inputted multiplexed optical signal is separated by an optical branching section into C-band multiplexed optical signal and L-band multiplexed optical signal, and the C-band multiplexed optical signal and L-band multiplexed optical signal are optically amplified by a C-band optical amplifier and an L-band optical amplifier, respectively. The amplified optical signals are combined by an optical combiner, and thus combined optical signal is outputted therefrom. The backward ASE light generated in the L-band optical amplifier upon optical amplification is blocked by an optical filter disposed between the optical amplifier and the optical branching section, so as to be prevented from traveling backward and being inputted to and amplified by the C-band optical amplifier, whereby the deterioration of noise characteristics is restrained.