PMD-Induced Crosstalk in Ultrahigh-Speed Polarization-Multiplexed Optical Transmission in the Presence of PDL

We present a new type of crosstalk in a polarization-multiplexed ultrahigh-speed transmission caused by polarization-mode dispersion (PMD) in the presence of polarization-dependent loss (PDL). When PMD and PDL are both present, the orthogonality between two principal states of polarization (PSP) is reduced. As a result, crosstalk inevitably occurs between two polarizations and prevents the two channels from being separated completely during polarization demultiplexing. The system impact of these effects in a polarization-multiplexed terabit/s transmission is also demonstrated experimentally.