Patent ID: 7627244
Filing Date: 2009-12-01
Classification: H04B

Abstract:
1. An optical transmission apparatus comprising: a preamplifier for pre-amplifying a wavelength-multiplexed signal beam inputted through an input transmission line; a first control unit for controlling said preamplifier so that amplified spontaneous emission including all wavelength bands of the wavelength-multiplexed signal beam is outputted, with said wavelength-multiplexed signal beam not inputted; a wavelength demultiplexing unit for demultiplexing the wavelength-multiplexed signal beam amplified by said preamplifier into a plurality of wavelength components, and for demultiplexing the amplified spontaneous emission from said preamplifier into a plurality of wavelength components; an add/drop processing unit for performing an adding/dropping process on signal beams at the respective wavelengths; a multiplexing unit disposed in a lower stream than said add/drop processing unit to wavelength-multiplex the signal beams at the respective wavelengths undergone the adding/dropping process and to output through an output transmission line; a second control unit for controlling said add/drop processing unit so that wavelength components of the amplified spontaneous emission outputted from said wavelength demultiplexing unit are outputted as they are toward said multiplexing unit; an optical power monitor for detecting an optical power of each of the wavelength components of said amplified spontaneous emission outputted from said add/drop processing unit under control of said second control unit; a determining unit for determining a continuity state of each of optical propagation paths of the corresponding wavelength components in an upper stream than said optical power monitor based on corresponding result of monitoring by said optical power monitor; and a variable attenuator for variably attenuating the optical power of each of the wavelength components from said add/drop processing unit; wherein, said optical power monitor comprises: a first optical power monitor for monitoring the optical power of each of the wavelength components of the amplified spontaneous emission outputted from said add/drop processing unit in the upper stream than said variable attenuator; a second optical power monitor for monitoring the optical power of each of the wavelength components of the amplified spontaneous emission outputted from said add/drop processing unit from the amplified spontaneous emission wavelength-multiplexed by said multiplexing unit; a third optical power monitor for monitoring the optical power of each of the wavelength components attenuated by said variable attenuator in the upper stream than said multiplexing unit; and an attenuation quantity constant controlling unit for controlling the variable attenuator based on results of monitoring by said first and third power monitors so that an attenuation quantity of said variable attenuator for each of the wavelength components is constant; said determining unit comprises: a first determining unit for determining a continuity state of each of said optical propagation paths of the corresponding wavelength components in the upper stream than said first optical power monitor based on corresponding result of monitoring by said first optical power monitor; and a second determining unit for determining the continuity state of each of said optical propagation paths of the corresponding wavelength components in the upper stream than said second optical power monitor and the lower stream than said third optical power monitor based on corresponding result of monitoring by said second optical power monitor.