Differential polarization time coding for PolDM systems without PMD compensator

Polarization division multiplexed (PolDM) systems have become a popular research field in modern fiber-optic communication systems due to their potential of doubling the spectral efficiency. However, polarization mode dispersion (PMD) is a major obstacle for PolDM systems, especially in long-haul applications. Existing techniques used to compensate for PMD are complicated and expensive to build. We propose a new differential polarization time coding (DPTC) scheme for PolDM systems, which is similar to differential space time coding (DSTC) schemes in wireless systems. Simulation results with optical distance of 2000 km show that DPTC can increase the PMD tolerance significantly with little added complexity.