Measurements of mode conversion coefficients in graded-index fibers

Abstract

A new method of measuring mode conversion coefficients in multimode fibers is proposed. The principle is based on the phenomenon that modal power propagating along a fiber undergoes a gradual change due to mode coupling and mode-dependent losses. Application of the principle has made it possible to measure mode conversion coefficients of a graded-index fiber that, to the authors' belief, had not been reported before. In the experiment, it was found that the mode conversion coefficient is roughly independent of the mode order. A resolution limit of the mode analyzing technique is also discussed for graded-index fibers.