Polarization anisotropic gain behavior in elliptical-core rare-earth-doped fibers

We report the first dedicated study on the polarization properties of fiber lasers based on rare- earth-doped single-mode elliptical-core fibers. More specifically, with the use of elliptical-core (2:1) Nd-doped fibers, we report evidence of significant gain anisotropy, primarily due to the differences in the modal overlap in the two orthogonal polarizations.