Clock-tone regeneration due to higher order PMD in NRZ systems

We show that the clock tone will be regenerated in the presence of higher order fiber-based polarization-mode dispersion (PMD) in nonreturn-to-zero systems. Due to the frequency-dependent optical propagation induced by higher order PMD, the extracted clock-tone power of the received data correlates with higher order PMD and is independent of first-order PMD.