Patent ID: 7650074
Filing Date: 2010-01-19
Classification: H04B,H04J

Abstract:
1. An apparatus receiving a light including a wavelength division multiplexed (WDM) light in which a plurality of optical signals at different wavelengths in a waveband are multiplexed together, the apparatus comprising: a demultiplexer configured to demultiplex the WDM light in the light received by the apparatus into the plurality of optical signals; an optical attenuator configured to adjust a level of a respective demultiplexed optical signal; a multiplexer configured to multiplex together the demultiplexed plurality of optical signals after the optical attenuator attenuates the level of said respective demultiplexed optical signal, to thereby provide an adjusted, WDM light; a bypass unit configured to route amplified spontaneous emission (ASE) light in the light received by the apparatus and which is outside of the waveband so that the routed ASE does not pass through the demultiplexer and the multiplexer; a coupler configured to multiplex together the adjusted, WDM light provided by the multiplexer and the ASE light routed by the bypass unit; and an optical amplifier having an amplification band that includes the waveband and the routed ASE light, and is provided at at least one of a stage prior to the demultiplexer so that the optical amplifier amplifies the WDM light and the ASE light in the light received by the apparatus, and a stage subsequent to the coupler so that the optical amplifier amplifies adjusted, WDM light and the ASE light multiplexed together by the coupler.