Shuttle pulse measurements of pulse spreading in an optical fiber

Partially transparent mirrors were pressed against fiber ends so that the length dependence of pulse spreading could be determined without cutting the fiber into pieces. Measurements were made by comparing the widths of laser pulses (lambda = 0.9 microm) through the output end mirror, which returned from 9(1/2) successive round trips (2014-m extrapolated length) along a 106-m multimode fiber. Mode mixing was significant in this fiber (fabricated by Corning Glass Works), and a square root of length pulse width dependence was observed. However, some of the mode-mixing effects on pulse width were caused by the way in which the fiber was wound on a drum.