Optical Power Flow in Multimode Fibers

Telephone and Telegraph Company TECHNICAL JOURNAL SYSTEM Vol. 51, No. 8, Octobcr, 1972 Printed in U.S.A. Optical Power Flow in Multimode Fibers By D. GLOGE (Manuscript received May 8, 1972) Loss, coupling, and delay differences am ong the modes of multimode fibers influence their transmission characteristic in a complicated way. An approximation of the modes by a continuum leads to a comprehensive description of these interrelations. We relate the mode power distribution to the far-field output and calculate these distributions as functions of the fiber length and the input. We report measurements of the far-field distributes at various lengths of a cladded low-loss multimode fiber. A comparison of theory and experiment yields a quantitative estimate of the mode coupling involved. We associate this coupling with random irregularities of the fiber configuration and straightness, and construct a quantitative model of such irregularities.