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Title: Gain-induced Kerr beam cleaning in a femtosecond fiber amplifier

Kerr beam cleaning is a nonlinear phenomenon in graded-index multimode fiber where power flows toward the fundamental mode, generating bell-shaped output beams. Here we study beam cleaning of femtosecond pulses accompanied by gain in a multimode fiber amplifier. Mode-resolved energy measurements and numerical simulations showed that the amplifier generates beams with high fundamental mode content (greater than 30% of the overall pulse energy) for a wide range of amplification levels. Control experiments using stretched pulses that evolve without strong Kerr nonlinear effects showed a degrading beam profile, in contrast to nonlinear beam cleaning. Temporal measurements showed that seed pulse parameters have a strong effect on the amplified pulse quality. These results may influence the design of future high-performance fiber lasers and amplifiers.

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Award ID(s):
Author(s) / Creator(s):
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Publisher / Repository:
Optical Society of America
Date Published:
Journal Name:
Journal of the Optical Society of America B
0740-3224; JOBPDE
Page Range / eLocation ID:
Article No. 1510
Medium: X
Sponsoring Org:
National Science Foundation
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