Distributed measurement of mode group effective refractive index difference in a few mode optical fibers

The possibility to perform distributed measurements of the effective refractive index difference between distinct modes in few mode optical fibers is demonstrated using phase sensitive optical time domain reflectometry. Effective refractive index differences between LP02, LP21a and LP21b modes are measured with for a spatial resolution of 24m. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement