Mode Selective Distributed Characterization of Few-Mode Fibers

A new scheme for spatially resolved measurement of mode dispersion, modal birefringence and differential chromatic dispersion in few-mode fibers is presented and experimentally validated on a weakly-coupled, 4-mode-group fiber. The method relies on spectral correlation analysis between fiber's coherent Rayleigh backscattering traces generated by each of the supported mode groups, measured through optical frequency domain reflectometry. The presented technique provides a viable and effective way to measure modal and chromatic dispersion properties between arbitrary pairs of modes of the probed fiber, providing sub-picosecond delay resolution and centimeter-scale spatial resolution.