Nonlinear Polarization Scattering in Polarization-Division-Multiplexed Coherent Communication Systems

Abstract

Polarization-division-multiplexing (PDM) [1–4], which transmits two channels with orthogonal states of polarization (SOPs) at an identical wavelength, was proposed long time ago to double the capacity of fiber-optic communication systems, but it was only until recently that the technique attracted much attention. The increasing demand for communication capacity requires high spectral efficiency fiberoptic communication systems, and PDM is an effective technique to double the spectral efficiency. Advances in digital signal processing and high speed electronics make coherent detection an attractive technique for optical communication systems [5–9]. With coherent detection and digital signal processing, polarization demultiplexing, which was considered cumbersome in the optical domain, can be easily performed in the electrical domain, although there is still some interest to do polarization demultiplexing using optical methods [10–12]. Therefore, PDM is almost considered a standard option for today’s optical coherent systems.