What is polarization mode dispersion Fiber
1. Polarization mode and polarization mode dispersion (PMD)
In single mode fibers, light pulses are actually composed of two distinct polarization modes. The electric field vector of the two modes are perpendicular to one another, or called orthogonal. Normally the two polarization modes behave just the same in the fiber which means they can not be distinguished.
But that is only the theory with a perfect symmetrical fiber and no outside force on the fiber. Since the world is not perfect and neither is the fiber, these two polarization modes do behave differently in real world fibers.
Stresses within the fiber, and outside forces applied to the fiber cause the refractive index of glass to differ slightly for these two polarization modes. This phenomenon is called birefringence.
Birefringence makes these two polarization modes travel at slightly different speed. This speed difference broadens lightwave signal just as other dispersions and this fact is called Polarization Mode Dispersion (PMD).
2. PMD and its impact on single mode fiber optic systems
The potential effects of polarization mode dispersion became significant only a few years ago when high speed fiber optic digital communication systems came to play, such as the 40Gbit/s systems.
Polarization mode dispersion (PMD) is smaller in magnitude than other types of dispersions, but it is more difficult to compensate for, at least until now. PMD becomes a problem in systems with data rates higher than 2.5Gbit/s. PMD makes more challenge to sending higher data rates over long distance..
Related reading:Polarization Maintaining Fiber Components quantum analyzer wireless remote control Best Quality Tungsten Bracelets