Polarization-maintaining Optical Fibres

Polarization-maintaining Optical Fibres

Polarization-maintaining optical fibers (PM fibers) are a type of optical fiber that is designed to maintain the polarization of light as it propagates through the fiber. These fibers are used in applications where the polarization of the light is critical, such as in fiber optic gyroscopes, interferometers, and telecommunications systems. PM fibers are made by introducing stress into the fiber during the manufacturing process. This stress causes the fiber to have a birefringence, which means that it has different refractive indices for light polarized in different directions. The stress is typically introduced by placing the fiber in a furnace and heating it to a high temperature while it is stretched. The birefringence of the PM fiber causes it to have two principal axes of polarization, which are known as the fast axis and the slow axis. When light is launched into the fiber, it will split into two orthogonal polarization states that propagate at different speeds along the fast and slow axes. This differential propagation causes the polarization of the light to be maintained as it travels through the fiber. PM fibers are typically more expensive than standard single-mode fibers, and they require more careful handling during installation and use. However, they are essential for many high-performance applications where the polarization of the light must be maintained.

polarization, optical fiber, birefringence, fast axis, slow axis

— Christopher White