Patent ID: 9735916
Date: 2017-08-15
CPC Classifications: H04B,H04J

Claim:
1. An optical receiver comprising: an optical brancher configured to branch polarization multiplexed light to a first polarization multiplexed light and a second polarization multiplexed light and output the first polarization multiplexed light and the second polarization multiplexed light to a first output path and a second output path which is different from the first output path, respectively, the polarization multiplexed light in which a pilot signal is superimposed on at least one of a first polarization and a second polarization; an optical fiber, corresponding to the first output path, configured to transmit the first polarization multiplexed light; a first polarization rotator, coupled to the first output path, configured to control a first polarization state of the first polarization multiplexed light output from the optical fiber; a first polarization separator, coupled to the second output path, configured to separate the second polarization multiplexed light which is output from the second output path into a third polarization and a fourth polarization; a second polarization separator, coupled to an output of the first polarization rotator and being different from the first polarization separator, configured to perform polarization separation on the first polarization multiplexed light output from the first polarization rotator and output the separated first polarization multiplexed light to a first port and a second port; a controller configured to control the first polarization rotator based on one of a first pilot signal included in the third polarization and a second pilot signal included in the fourth polarization in such a manner that the first polarization state of the first polarization multiplexed optical signal output from the first polarization rotator matches a polarization axis of the second polarization separator; a second polarization rotator, provided between the optical brancher and the first polarization separator and in parallel with the first polarization rotator, configured to control a second polarization state of the second polarization multiplexed light and to supply the controlled second polarization multiplexed light to the first polarization separator; optical receivers, coupled to the second polarization rotator, configured to convert the third polarization and the fourth polarization output from the first polarization separator to electrical signals, respectively; and filters, coupled to the respective optical receivers, configured to extract the first pilot signal from the third polarization and the second pilot signal from the fourth polarization, respectively.