Advantages of polarization-maintaining fiber
Polarization-maintaining fibers work by intentionally introducing a systematic linear in the fiber, so that there are two well defined polarization modes which propagate along the fiber with very distinct phase velocities. The beat length Lb of such a fiber (for a particular wavelength) is the distance (typically a few millimeters) over which the wave in one mode will experience an additional delay of one wavelength compared to the other polarization mode. Thus a length Lb /2 of such fiber is equivalent to a Maintaining polarization improves sensitivity, accuracy, and noise rejection in strain, temperature, or vibration measurements. For example, availability can be limited for certain active fibers, for fibers with unusual values of the effective mode area.
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