Polarization-maintaining fiber short axis
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. Their pure silica core provides protection from photodarkening, which makes them ideal for use at short wavelengths. In this article, the latest in FOC's series covering specialty fibers and their fabrication, we discuss polarization-maintaining (PM) fibers and the various approaches used to make them. There are several PM fiber designs – all quite different and each with its own complexities in preform.
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