Birefringence and polarization mode dispersion caused by thermal stress in single-mode fibers with various core ellipticities

Modal birefringence and polarization mode dispersion in single-mode fibers with various core ellipticities were measured at wavelengths in the m region. From the measurements and numerical calculations of the birefringence and the modal dispersion due to a geometrical anisotropy by the point-matching principle, normalized frequency dependence of the birefringence and the dispersion caused by a thermal stress were clearly obtained for various core ellipticities. Comparing the evaluated results with the calculation within the first-order perturbation theory, it is found that the evaluated curves for core ellipticity of 20 percent are coincident fairly well with that of theory, while the curves for core ellipticity of 58 percent are shifted markedly toward higher υ value region.