Patent ID: 7151898

Claim:
A device for reducing distortion in an optical signal, comprising: a PMD detector for sensing first order PMD and second order PMD in the optical signal and for generating at least one feedforward control signal in accordance with the sensed first and second order PMD, and a PMD compensator, having at least three concatenated segments with first order PMD {right arrow over (τ)} 1 , {right arrow over (τ)} 2 , {right arrow over (τ)} 3 , and rotation matrices R 1 , R 2 , R 3 , respectively, and having at least three polarization controllers with respective rotation matrices C 0 , C 1 , C 2 , and a variable delay in series between two of the at least three polarization controllers, the PMD compensator for altering the optical signal in accordance with the at least one feedforward control signal to generate a corrected optical signal that is substantially devoid of first and second order PMD, wherein the at least one feedforward control signal determines values for the rotation matrices C 0 , C 1 , C 2, and includes a signal of the magnitude of the solution of {right arrow over (A)} given by {right arrow over (τ)} c −{right arrow over (τ)} 3 ={right arrow over (B)}+{right arrow over (A)} where {right arrow over (τ)} c is the first order PMD in a portion of the PMD compensator lacking the first of the at least three polarization controllers, {right arrow over (B)}=R 3 C 2 {right arrow over (τ)} 2 and {right arrow over (A)}=R 3 C 2 R 2 C 1 {right arrow over (τ)} 1 .