Patent ID: 8977137
Filing Date: 2015-03-10
Classification: H04B

Abstract:
1. An apparatus configured to be implemented in a multi-channel optical network including a plurality of optical receivers that are optically coupled to one or more of a plurality of optical transmitters and polarization dependent loss (PDL) sources implemented between at least some of the optical transmitters and the optical receivers, the apparatus comprising: a first evaluation module located at a first optical receiver of the plurality of optical receivers, the first evaluation module configured to: a second evaluation module located at a second optical receiver of the plurality of optical receivers, the second evaluation module configured to: a first monitor located between the first PDL source and the first evaluation module and configured to measure an actual optical signal-to-noise ratio (OSNR) in the first channel; a second monitor located between the second PDL source and the second evaluation module and configured to measure an actual OSNR in the second channel; a first feedback loop that couples the first evaluation module and the first monitor to a first polarization controller, wherein the first polarization controller is included in the first optical transmitter and is configured to receive the first polarization rotation matrix from the first evaluation module and the OSNR from the first monitor via the first feedback loop and in response to a determination that an optical signal quality issue of the first channel is caused by the PDL rather than the OSNR, rotate a state of polarization (SOP) of the first channel at the first optical transmitter based on the first polarization rotation matrix to reduce the PDL caused by the first PDL source in the first channel; and a second feedback loop that couples the second evaluation module and the second monitor to a second polarization controller, wherein the second polarization controller is included in the second optical transmitter and is configured to receive the second polarization rotation matrix from the second evaluation module and the OSNR from the second monitor via the second feedback loop and in response to a determination that an optical signal quality issue of the second channel is caused by the PDL rather than the OSNR, rotate the SOP of the second channel at the second optical transmitter based on the second polarization rotation matrix to reduce the PDL caused by the second PDL source in the second channel.