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Proceedings Paper

Theoretical analysis of effect of pump and signal wavelengths on modal instabilities in Yb-doped fiber amplifiers
Author(s): Shadi Naderi; Iyad Dajani; Jacob Grosek; Timothy Madden; Thien-Nam Dinh
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Paper Abstract

We present, using numerical simulations, investigations of the modal instability thresholds in high-power Yb-doped fiber amplifiers. We use a time-dependent temperature solver coupled to the optical fields and population inversion equations to determine the temporal dynamics of the modal content of the signal as well as the modal instability threshold. Our numerical code is optimized to achieve fast computations; thus allowing us to perform efficient detailed numerical studies of fiber amplifiers ranging in lengths from 1-20 meters using various pump and seeding wavelengths. Simulation results indicate promising modal instability suppression through gain tailoring, tandem pumping, or through seeding at an appropriate wavelength. We examine the threshold of an amplifier pumped using fiber lasers operating at 1018 nm; similar to the multi-kilowatt single-mode fiber laser demonstrated by IPG. In this case, we show an increase in threshold of 370%. By simply seeding at other wavelengths, as low as 1030 nm, a 60% suppression of the modal instability threshold can also be realized. Furthermore, we show that gain tailoring is an effective mitigation technique leading to an appreciable suppression of the instability in a fiber design that has already been experimentally tested.

Paper Details

Date Published: 20 February 2014
PDF: 7 pages
Proc. SPIE 8964, Nonlinear Frequency Generation and Conversion: Materials, Devices, and Applications XIII, 89641W (20 February 2014); doi: 10.1117/12.2044143
Show Author Affiliations
Shadi Naderi, Ball Aerospace & Technologies Corp. (United States)
Iyad Dajani, Air Force Research Lab. (United States)
Jacob Grosek, Air Force Research Lab. (United States)
Timothy Madden, Air Force Research Lab. (United States)
Thien-Nam Dinh, Univ. of Delaware (United States)

Published in SPIE Proceedings Vol. 8964:
Nonlinear Frequency Generation and Conversion: Materials, Devices, and Applications XIII
Konstantin L. Vodopyanov, Editor(s)

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