Optical transmission apparatus, continuity testing method therein, and optical transmission system

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 an optical power of each of the wavelength components from said add/drop processing unit;
• wherein, said optical power monitor comprises:
• a first 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 in the lower stream than 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
• a power equalizing control unit for controlling attenuation quantities of said variable attenuator based on a result of monitoring by said second optical power monitor so that the optical powers of the wavelength components monitored by said second optical power monitor are equalized;
• and
• said determining unit comprises:
• a first determining unit for determining a continuity state of an optical propagation path of each of the wavelength components in the upper stream than said first optical power monitor based on a result of monitoring by said first optical power monitor;
• and
• a second determining unit for measuring, from results of monitoring by said first and third optical power monitors, the attenuation quantity of said variable attenuator controlled based on a result of monitoring by said second optical power monitor to determine the continuity state of the optical
• propagation path of each of the wavelength components in the upper stream than said second optical power monitor and the lower stream than said third optical power monitor based on a result of the measurement.

A continuity testing method in an optical transmission apparatus including a preamplifier for pre-amplifying a wavelength-multiplexed signal beam inputted through an input transmission line, a wavelength demultiplexing unit for wavelength-demultiplexing the wavelength-multiplexed signal beam from said preamplifier into wavelengths, an add/drop processing unit for performing an adding/dropping process on a signal beam at each of the wavelengths wavelength-demultiplexed by said wavelength demultiplexing unit, and a multiplexing unit disposed in a lower stream than said add/drop processing unit to wavelength-multiplex signal beams at the respective wavelengths undergone the adding/dropping process and to be outputted through an output transmission path, comprising the steps of:

• controlling said preamplifier so that amplified spontaneous emission including all wavelength bands to be undergone an output route switching process by said add/drop processing unit is outputted therefrom, with said wavelength-multiplexed signal beam not inputted;
• controlling said add/drop processing unit so that wavelength components of said amplified spontaneous emission outputted from said wavelength demultiplexing unit are outputted as they are toward said multiplexing unit;
• monitoring an optical power of each of the wavelength components of the amplified spontaneous emission outputted from said add/drop processing unit and propagated through a plurality of optical propagation paths, respectively;
• and
• determining a continuity state of each of an optical propagation paths in an upper stream than a position at which the optical power is monitored, on the basis of corresponding result of the monitoring, wherein the optical power of each of the wavelength components of the amplified spontaneous emission outputted from said add/drop processing unit is monitored by a first optical power monitor disposed in the upper stream than said multiplexing unit;
• the continuity state of an optical propagation path of each of the wavelength components in the upper stream than said first optical power monitor is determined on the basis of based on a result of monitoring by said first optical power monitor;
• when the continuity state is determined to be normal as a result of determination of the continuity state on the basis of the result of monitoring by said first optical power monitor, the optical power of each of the wavelength components of the amplified spontaneous emission outputted from said add/drop processing unit is monitored by a second optical monitor disposed in the lower stream than said multiplexing unit;
• and
• the continuity state of an optical propagation path of each of the wavelength components in the upper stream than said second optical power monitor and the lower stream than said first optical power monitor is determined on the basis of based on a result of monitoring by said second optical power monitor.

An optical transmission system in which a first optical transmission apparatus being connected to a second optical transmission apparatus through an input transmission line,

• said first optical transmission apparatus comprising:
• a preamplifier for pre-amplifying a wavelength-multiplexed signal beam inputted through said 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 from said second optical transmission apparatus;
• 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 the 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 an optical propagation path of the corresponding wavelength components in an upper stream than said optical power monitor on the basis of 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 en-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.

An optical transmission system in which a first optical transmission apparatus being connected to a second optical transmission apparatus through an input transmission line,

• said first optical transmission apparatus comprising:
• a preamplifier for pre-amplifying a wavelength-multiplexed signal beam inputted through said 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 from said second optical transmission apparatus;
• 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 the 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 an optical propagation path of the corresponding wavelength components in an upper stream than said optical power monitor on the basis of 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 a variable attenuator for variably attenuating an optical power of each of the wavelength components from said add/drop processing unit;
• wherein, said optical power monitor comprises:
• a first 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 in the lower stream than 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
• a power equalizing control unit for controlling attenuation quantities of said variable attenuator based on a result of monitoring by said second optical power monitor so that the optical powers of the wavelength components monitored by said second optical power monitor are equalized;
• and
• said determining unit comprises:
• a first determining unit for determining a continuity state of an optical propagation path of each of the wavelength components in the upper stream than said first optical power monitor based on a result of monitoring by said first optical power monitor;
• and
• a second determining unit for measuring, from results of monitoring by said first and third optical power monitors, the attenuation quantity of said variable attenuator controlled based on a result of monitoring by said second optical power monitor to determine the continuity state of the optical propagation path of each of the wavelength components in the upper stream than said second optical power monitor and the lower stream than said third optical power monitor based on a result of the measurement.