Polarization maintaining fiber is also named polarization preserving fiber or HI-BI fiber. Pm fiber has very high birefringence deliberately induced to enable them to function as the name implies. The high birefringence is achieved by having very high asymmetry in the fiber core or fiber cladding. Both designs can make the fiber well pronounced slow and fast in terms of velocity of the polarized light propagation-axes.
Disadvantage of pm fiber is the high cost and its high attenuation. And installation and maintenance of Polarization maintaining fiber is also high. For these reasons the PM fiber products are not widely used in today’s fiber optic communication systems.
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