Abstract

A technique is introduced that determines power distribution in fibers from the measured near-field pattern, assuming that: (1) the optical power distributes uniformly among degenerated modes with the same propagation constant, (2) enough modes are excited to ensure the validity of calculation by geometrical optics, and (3) the phase of each propagation mode has no correlation. Experiments verifed that the fibers have the function of flattening power distribution among modes with the same propagation constant. This fact shows that assumption (1) does not severely limit the applicability of the technique. Wave optical calculation is done to determine the numbers of modes that must be excited to satisfy assumption (2). As an example of application of the technique, differential mode attenuation of graded-index fibers is determined from longitudinal variation of the measured near-field pattern.

© 1979 Optical Society of America

Diameter determination of graded-index optical fibers from backward-scattered pattern

Charoon Saekeang and Pak L. Chu
Appl. Opt. 18(19) 3276-3281 (1979)

Measurement of refractive-index profile and transmission characteristics of a single-mode optical fiber from its exit-radiation pattern

Kazuo Hotate and Takanori Okoshi
Appl. Opt. 18(19) 3265-3271 (1979)

Relations between near-field and far-field intensities, radiance, and modal power distribution of multimode graded-index fibers

Gerhard K. Grau and Ottokar G. Lerminger
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Ernst Brinkmeyer
Appl. Opt. 18(6) 932-937 (1979)

Propagation constants and group delays of guided modes in graded-index fibers: a comparison of three theories

Gunnar Jacobsen and J. J. Ramskov Hansen
Appl. Opt. 18(16) 2837-2842 (1979)