Polarization fluctuation monitoring apparatus, communication system, and polarization fluctuation monitoring method

A communication system comprising:

• one or more transmitters, each of which transmits a main signal;
• a transmission path for transmitting one or more main signals transmitted from the one or more transmitters;
• optical receivers, each of which receives the one or more main signals transmitted through the transmission path;
• and
• a polarization fluctuation monitoring apparatus for monitoring a polarization fluctuation in the transmission path, wherein
• the transmission path includes a weakly-coupled multicore fiber including a first core and a second core, and
• the polarization fluctuation monitoring apparatus includes:
• a polarization characteristic measurement instrument for measuring polarization characteristics of a first monitoring signal transmitted in a first direction using the first core and a second monitoring signal transmitted in a second direction opposite to the first direction using the second core in the transmission path;
• at least one memory storing instructions;
• and
• at least one processor configured to execute the instructions to:
• detect polarization fluctuation occurring in the weakly-coupled multicore fiber based on the measured polarization characteristics;
• and
• estimate a position where the polarization fluctuation occurred in the transmission path based on the detected polarization fluctuation.

A polarization fluctuation monitoring method comprising:

• measuring polarization characteristics of a first monitoring signal transmitted in a first direction using a first core and a second monitoring signal transmitted in a second direction opposite to the first direction using a second core in a transmission path including a weakly-coupled multicore fiber including the first core and the second core;
• detecting polarization fluctuation occurring in the weakly-coupled multicore fiber based on the measured polarization characteristics;
• and
• estimating a position where the polarization fluctuation occurred in the transmission path based on the detected polarization fluctuation.