We demonstrate, for a widely used model of channels with polarization
dependent loss (PDL), that channel capacity is achieved by a simple
interference cancellation scheme in conjunction with a universal precoder.
Crucially, the proposed scheme is not only information-theoretically optimal,
but it is also exceptionally simple and concrete. It transforms the PDL channel
into separate scalar additive white Gaussian noise channels, allowing
off-the-shelf coding and modulation schemes designed for such channels to
approach capacity. The signal-to-noise ratio (SNR) penalty incurred under 6 dB
of PDL is reduced to the information-theoretic minimum of a mere 1 dB as
opposed to the 4 dB SNR penalty incurred under naive over-provisioning.Comment: Submitted to Journal of Lightwave Technolog