Polarization Mode Dispersion
A basic property of single-mode fibers. PMD affects the magnitude of the transmission rate and results from the difference in propagation times of the energy of a given wavelength, which is split into two polarization axes that are at right angles to each other. Main causes of PMD are non-circularities of the fiber design and external applied stress (macro-bending, micro-bending, twist and temperature variations).
![SP4420_large](https://wiki.commscopetraining.com/wp-content/uploads/2018/10/SP4420_large-1-150x150.png)