US Patent 7650074 Optical transmission apparatus

An optical transmission apparatus includes a demultiplexing unit that demultiplexes a light input to the optical transmission apparatus into a plurality of lights; an optical attenuator that adjusts an output level of a light within a band that includes a signal light from among demultiplexed lights; a bypass unit that bypasses a light outside the band from among demultiplexed lights; a multiplexing unit that multiplexes adjusted light and the light from the bypass unit; and an optical amplifier that amplifies input light. The optical amplifier is provided at least one of a stage prior to the demultiplexing unit and a stage subsequent to the multiplexing unit.