Patent ID: 8737840

Claim:
An optical transmission system comprising; a digital processor; an optical transmitter that combines first signal light and second signal light having different polarization orientations to generate a transmission signal light and outputs the transmission signal light to a transmission path; and an optical receiver that separates the transmission signal light input from the optical transmitter via the transmission path into the first signal light and the second signal light, wherein the optical transmitter comprises a coupler that multiplexes polarization combined signal lights different in wavelength to generate a multiplexed signal beam and a polarization changer that continuously changes a state of polarization of the transmission signal light at a first variation frequency, wherein the optical receiver comprises a polarization reverse-changer that continuously changes the state of polarization of the transmission signal light at a second variation frequency in a reverse direction of the change that the polarization changer applies, and a divider that demultiplexes the multiplexed signal beam into the polarization combined signal lights different in wavelength, wherein the digital processor comprises a digital circuit that adaptively estimates a polarization property of the transmission path and demodulates the polarization combined signal lights demultiplexed in the divider, and wherein a difference between the first variation frequency of the polarization changer and the second variation frequency of the polarization reverse-changer is set to be not greater than a response frequency based on abilities of demodulation in the digital processor.