22 March 2013 Numerical studies of modal instabilities in high-power fiber amplifiers
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Abstract
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.
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Shadi Naderi, Shadi Naderi, Iyad Dajani, Iyad Dajani, Timothy Madden, Timothy Madden, Bemjamin Ward, Bemjamin Ward, Craig Robin, Craig Robin, Jake Grosek, 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); doi: 10.1117/12.2006571; https://doi.org/10.1117/12.2006571
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