Performance analysis of DPSK modulated signals in optical transmission link with PMD and PDL

Polarization effects such as polarization mode dispersion (PMD) and polarization dependent loss (PDL) have become the critical limiting factors for long haul high bit rate optical fiber transmission. This paper use waveplate models to simulate the statistical performance of optical link with PMD and PDL in 40Gbit/s optical system. Three DPSK modulation formats are compared each other for their tolerance against PMD and PDL. The 33% RZ-DPSK is superior to the other two DPSK formats, the 50% RZ-DPSK and the CSRZ-DPSK whose duty cycle is 67% when only PMD is considered. And in case of PDL, the outages for three DPSK formats do not show obvious changes with the increasing of PDL. Furthermore, the performance of two RZ-DPSK formats, whose duty cycles are 33% and 50% respectively, is superior to that of CSRZ-DPSK. This shows that modulation format with narrower pulse width owns more high tolerance against PMD and PDL, therefore the CSRZ-DPSK format shows poorer performance when it is compared with the other two DPSK formats.