All-frequency PMD compensator in feedforward scheme

We present the architecture of a broad-band polarization mode dispersion (PMD) compensator in a feedforward PMD compensation scheme. It is comprised of four stages. The net effect of the first two stages is equivalent to a frequency dependent polarization rotation that aligns all PMD vectors into a common direction. The third stage compensates the frequency dependent variable differential group delay (DGD) and the last stage compensates for the isotropic dispersion created by the first three stages. In Stokes space formulation, we describe the algorithm to find the required rotation angles of each stage using the PMD concatenation rule, and show that these rotation angles can be synthesized using all-pass filters (APF) in a compact integrated optics circuit. Through numerical simulations, we show significant improvement of the signal quality as a result of the compensation.