2.1 Optical Fibers2.2 Polarization and Radiation Field2.2.1 Jones Representation2.2.2 Stokes Representation2.2.3 Mueller Matrix2.2.4 Four-Dimensional Representation2.2.5 Evolution of Polarization in Optical Fiber2.3 Polarization Effects in Lightwave Systems2.3.1 Polarization Mode Dispersion (PMD)2.3.2 PMD Models2.3.3 PMD and PDL Impairments2.3.4 Birefringence2.3.5 Linear Birefringence2.3.6 Circular Birefringence2.3.7 Birefringence Models2.3.8 Model for SSMF with Linear Birefringence2.3.9 Model for Twisted SSMF2.3.10 SOP Fluctuations Compensation2.4 Novel Multilevel Polsk Coherent System2.4.1 Birefringence as a Resource2.4.2 System Description2.4.3 Statistical Analysis2.4.4 Mathematical Model2.4.5 Experimental Results2.4.6 Performance Evaluation2.4.7 Coherent Detection Performance2.4.8 Direct Detection Performance2.5 Multilevel Combined Phase and Polarization Shift Keying Modulation in Twisted Fibers2.5.1 The Phase Sphere2.5.2 A Novel Model in Twisted Fibers2.5.2.1 Transmitter2.5.2.2 Propagation in a Twisted Fiber2.5.2.3 Receiver2.5.3 System Performance Evaluation2.5.4 ConsiderationsReferences