Competence Center for Specialty Optical Fibers

Understanding polarization in waveguides is of fundamental importance for any photonic device and is particular relevant within the scope of fiber optics. Here we investigate the dependence of the geometry-induced polarization behavior of anti-resonant hollow core fibers on various parameters from the experimental perspective. A distinct dependence of the output polarization as function of number of core sides is found, which reduces for cores with more corners. The minimal output ellipticity was found at the wavelength of lowest loss near the center of the transmission band, whereas a substantial increase is found towards the resonances. The analysis showed that maximizing the amount of linearly polarized light at the fiber output demands both operating at the wavelength of lowest loss as well as carefully choosing the relative orientation of input polarization and main fiber symmetry axis. Due to their practical relevance we expect our findings to be very important in fields such as nonlinear photonics or interferometry.