What is polarization maintaining fiber

Polarization-maintaining fiber is a special type of single-mode fiber. Ordinary single-mode fibers can transmit randomly polarized light, while polarization-maintaining fibers can only transmit polarized light in one direction. In polarization-maintaining fibers, the polarization of linearly polarized light waves propagating into the fiber is maintained during propagation with little or no cross-coupling of optical power between polarization planes.