Polarization-maintaining Fibers- Essential and Special Applications

Types of Polarization-maintaining Fiber

Generally speaking, there are two types of polarization-maintaining fiber, single-mode and few-mode fibers. However, they are mostly single-mode fibers, only in extremely rare cases few-mode fibers, and apparently never highly multimode fibers. Otherwise, it is hard to produce sufficiently strong and uniform birefringence in the fiber glass over a sufficiently large core area where many modes can be guided.

Application of Polarization-maintaining fibers

The application of polarization-maintaining fibers is important and special. There are many diverse and special application of them, for example, they can be applied in fiber optic sensing, interferometry and quantum key distribution. They are commonly used in telecommunications for the connection between a source laser and a modulator as well, since the modulator requires polarized light as input. They are hardly used for long-distance transmission, because of its much more expensive price and higher attenuation than single mode fiber. Gyroscopes is another important application of polarization-maintaining fibers, which are widely applied in the aerospace industry.

Disadvantages

1.    More expensive.

2.    Not all kinds of fibers are available in polarization-preserving form.