Optical transmission system

An optical transmission system comprising:

• an optical transmitter configured to transmit an optical signal, where an X-polarized signal and a Y-polarized signal each having a predetermined frame structure are polarization-multiplexed, to an optical transmission path;
• an optical receiver configured to receive the optical signal that has propagated through the optical transmission path,
• the optical transmitter including:
• a delay generator configured to delay a frame start position of the Y-polarized signal, by a predetermined delay time, relative to that of the X-polarized signal, and
• the optical receiver including:
• a polarization splitter configured to split the received optical signal into two polarization signals which are orthogonal to each other;
• a time difference detector configured to detect a time difference of frame start positions between the two polarized signals;
• and
• a polarization identifying unit configured to identify which of the two polarized signals is the X-polarized signal or Y-polarized signal;
• and,
• an output switching unit configured to switch output destinations of the two polarized signals, based on an identification result of the polarization identifying unit.

An optical transmission system comprising:

• an optical transmitter configured to transmit an optical signal, where an X-polarized signal and a Y-polarized signal each having a predetermined frame structure are polarization-multiplexed, to an optical transmission path;
• an optical receiver configured to receive the optical signal that has propagated through the optical transmission path,
• the optical transmitter including:
• a delay generator configured to delay a frame start position of the Y-polarized signal, by a predetermined delay time, relative to that of the X-polarized signal, and
• the optical receiver including:
• a polarization splitter configured to split the received optical signal into two polarization signals which are orthogonal to each other;
• a time difference detector configured to detect a time difference of frame start positions between the two polarized signals;
• and
• a polarization identifying unit configured to identify which of the two polarized signals is the X-polarized signal or Y-polarized signal;
• wherein in the event that input of signals is interrupted, the optical transmitter continues to transmit the X-polarized signal and/or the Y-polarized signal in which scrambled signal(s) are/is frame-structured, and
• the delay generator continues to delay the frame start position of the Y-polarized signal, by the predetermined delay time, relative to that of the X-polarized signal.