Right- and left-handed twist in optical fibers

The effect of twist-induced variation of the output state of polarization on clockwise and counterclockwise torsion was measured in two standard optical fibers made by different manufacturers. It was' found that standard fiber samples may exhibit a different twist-induced polarization performance for right- and left-handed twists. In this work we compare the results obtained for two commercial fibers using linearly polarized input signals with azimuth angles between 0 and 150 degrees, within the 1520-1570 nm spectral range. In all cases these results could be described using the same theoretical model. We demonstrate that the different behavior observed for right- and left-handed twists for one of the samples can be explained by the presence of a residual torsion.