Polarization-Insensitive Four-Wave-Mixing-Based Wavelength Conversion in Few-Mode Optical Fibers

Abstract

We report theoretical and experimental results on a wavelength converter based on intermodal phase matching in a graded index three-mode elliptical-core fiber. Here, two copolarized pump waves propagate in one spatial mode, whereas a signal and the corresponding generated idler propagate in another mode. We demonstrate that the idler power is independent of the signal polarization in both a 1 km and a 50 m long fiber. We attribute this polarization insensitivity to the fast random birefringence of the fiber under investigation in combination with the copolarized pump configuration.