Nondiffracting polarization textures enabled by anisotropic loss

We report a mechanism for suppressing diffraction of skyrmionic polarization textures by leveraging anisotropic absorption in inhomogeneous media. We show that dichroic media with longitudinally varying degree of dichroism can compensate the diffraction spreading of the skyrmion tube, enabling the formation of non-diffracting Stokes skyrmions. In contrast to trapped waves in gradient-index media, we present a non-diffraction mechanism in media with uniform refractive index in the transversal direction, thus the finite-size vortex beams themselves experience diffraction but their combined polarization texture remains confined within a non-spreading tube. We also show the robustness of the non-diffraction mechanism under changes in the input beam size and under beam shifts along longitudinal and transversal directions.