Stress induced birefringence in such a fiber, or bending of the fiber, will cause a tiny amount of crosstalk between different modes. 1) Fiber axis misalignment at fiber connection interfaces, of discrete coupling result in sharp, distinct peaks in the x-talk such as connectors or fusion splices, typically causes extremely measurement trace, with the width of the peak determin d by. In fiber optics, polarization-maintaining optical fiber (PMF or PM fiber) is a single-mode optical fiber in which linearly polarized light, if properly launched into the fiber, maintains a linear polarization during propagation, exiting the fiber in a specific linear polarization state; there is. This standard specifies a method for measuring polarization crosstalk in single-mode, high-linear-birefringence (commonly referred to as polarization-maintaining or PM) optical fibers and assemblies. This standard applies to optical fibers and assemblies with connectors at one or both ends, as well. Cross-polarization coupling in polarization maintaining fiber induced by periodic mechanical stress. As a result, the value is not affected by the quality of the output connector of the PM fiber. The difference in index of refraction between the 'fast' and 'slow'.