Measurements of waveguide structure fluctuation in a multimode optical fiber by backscattering technique

Utility of a backscattering technique for measuring waveguide structure fluctuation along a fiber is confirmed quantitatively. The backscattering technique is applied to three graded-index fibers: one fiber has uniform structure and the others have core diameter and refractive-index difference changes along the fiber length. The structural parameter fluctuations measured by the technique are in good agreement with those measured directly by the interference microscopy at several positions along the fibers. The resolvability and accuracy of the measured results by the backscattering technique is also compared with the relative error of the direct measurements.