Provided that linearly polarized light is input in the polarization mode of either fast or slow axis, polarization crosstalk is represented by quenching ratio of orthogonal polarization modes at output edge; one is the polarized mode in the input direction, and the other is the leaking polarized mode in the orthogonal direction, as given by the following equation,
where Px, and Py is the power of light in X, and Y direction, respectively. The larger the birefringence is, the smaller the polarization crosstalk is, and the better the polarization maintaining property is. As light propagates in the fiber, the optical coupling occurs between polarization modes. Therefore, the polarization crosstalk is a function of the fiber length (in theory, linear function). The unit is “dB/100.” The standard requirement is -25 dB/100 m or lower.
The polarization crosstalk of PANDA fiber is little temperature-dependent in the range of -40 ~ +80 degree. Additionally, the polarization crosstalk of PANDA fiber is not degraded by torsion and bending, which may be applied in typical uses.