An optical Fiber in which the Polarization planes of Lightwaves launched into the fiber are maintained during propagation with little or no cross-coupling of Optical Power between the polarization modes.

Note 1: Cross Sections of polarization-maintaining optical fibers Range from elliptical to rectangular. Note 2: Polarization-maintaining optical fibers are used in special applications, such as in fiber optic sensing and interferometry. Synonym polarization-preserving (PP) optical fiber.