Location optimization and distribution of polarization-mode dispersion compensators using polarizers

This paper investigates the benefits of using compensators with either linear or elliptic variable polarizers in order to mitigate the effects of polarization-mode dispersion (PMD) in high-speed optical fiber transmission systems. Such compensators are characterized by only one or two degrees of freedom and the optical average power of the compensated signal is used as a monitor signal, which simplifies the control algorithm. We maximize the tolerable differential group delay for the compensated system with two different approaches. In the first, we optimize the position of the compensator along the transmission line. In the second, we distribute a number of compensators through the transmission line. The attenuation of the optical signal, caused by the use of polarizers in the PMD compensators, induces additional noise in amplified systems. We assess the impact of this impairment and show that the noise enhancement is limited in systems with erbium-doped fiber amplifiers operating in gain saturation.