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22 March 2013 Numerical studies of modal instabilities in high-power fiber amplifiers
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We present a detailed time-dependent numerical model of the modal instability phenomenon observed in Yb-doped fiber amplifiers. The thermal effects are captured by solving the heat equation in polar coordinate using a 2D, second-order, time-dependent, alternating direction implicit (ADI) method. The model captures the three power-dependent regions that are characteristic of the transfer of energy between the fundamental mode and the higherorder mode as a function of time. It is also shown that for the fiber configuration investigated, the modal instability threshold scales linearly over a wide range with the seed power. Furthermore, we present numerical results indicating that gain tailoring can increase the threshold. Two different gain-tailored fiber designs are simulated and compared.
© (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Shadi Naderi, Iyad Dajani, Timothy Madden, Bemjamin Ward, Craig Robin, and Jake Grosek "Numerical studies of modal instabilities in high-power fiber amplifiers ", Proc. SPIE 8601, Fiber Lasers X: Technology, Systems, and Applications, 86013F (22 March 2013);

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