Characterization of Rayleigh backscattering arising in various two-mode fibers

We experimentally characterize the mode dependent characteristics of Rayleigh backscattering (RB) arising in various two-mode fibers (TMFs). With the help of an all-fiber photonic lantern, we are able to measure the RB power at individual modes. Consequently, mode dependent power distribution of RB light caused by arbitrary forward propagation mode superposition can be obtained. The total RB power of the TMFs under test is higher than that of single mode fiber by at least 2 dB over the C band. Meanwhile, the RB light occurs among all guided modes in the TMFs with specific power ratios. The experimental characterization agrees well with the theoretical calculations.