Device and method for compensating for polarization mode dispersion in optical transmission

A device for compensating for PMD (polarization mode dispersion) that occurs in a transmission optical fiber in an optical transmission system, comprising:

• a polarization controller (PC) for converting the state and direction of polarization of a signal beam received through the transmission optical fiber;
• a polarization beam splitter for splitting the signal beam outputted from the PC into two mutually orthogonal polarization components, to transmit a first polarization component among the two components to a first path and send a second polarization component to a second path, and then combining the two polarization components with each other after they have been reflected from the ends of the first and second paths to transmit the combined beam to an output path;
• a variable delay line for variably applying a time delay to the first polarization component traveling over the first path;
• a Faraday rotation mirror for rotating a polarization component outputted from the variable delay line of the first path by a predetermined angle to reflect it;
• a PSP monitoring part for rotating a portion of the second polarization component traveling over the second path by a predetermined angle to reflect it and receiving the remaining portion thereof to output it as an electric signal;
• a PC controller for controlling the PC such that two orthogonal PSP components of the signal beam are aligned with two orthogonal axes of the polarization beam splitter using the signal outputted from the PSP monitoring part;
• an optical tap for branching the signal beam that is outputted from the polarization beam splitter to travel to the output path;
• and
• a delay line controller for controlling the variable delay line using the signal beam branched by the optical tap, to remove differential time delay between the first and second polarization components of the signal beam.