Strain effects on highly elliptical core two-mode fibers.

Longitudinal strains in optical fibers have been found to produce a large differential phase shift between the first-and second-order spatial modes propagating in a two-mode fiber. This differential phase shift between the modes is both calculated and measured to be dispersive with respect to wavelength. For fibers with highly elliptical core geometries, which propagate only one lobe orientation of the second-order mode, the differential phase shift is also found to be polarization dependent.