Observation of spectral broadening caused by self-phase modulation in highly multimode optical fiber.
We observed spectral broadening caused by self-phase modulation in 400- and 600-microm core diameter fibers using amplified, Q-switched, Nd:YAG laser pulses with peak powers to 150 kW. The degree of spectral broadening was not dependent linearly on the fiber length as in single-mode fibers because of the more complicated modal evolution in highly multimode fiber. Furthermore, even slight stress near the input end of the fiber reduced the observed broadening. The results have significant implications for the delivery of high-peak-power laser beams through optical fiber with high-output beam quality for industrial applications.
Feldman
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General Electric Corporate Research and Development, P.O. Box 8, Schenectady, New York 12301, USA.
Staver
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Lotshaw
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