Modeling of High-Power Fiber Laser Performance

Narrow line width fiber lasers have great potential for high-power directed energy applications. The beams of multiple fibers can be combined using spectral or coherent methods for scaling to high power levels. To successfully achieve goals of multi-kW fiber laser system scaling, accurate methods are needed to predict the performance of individual fibers and how their performance is affected by fiber properties. In response to this need, our team is developing a comprehensive physics-based fiber laser analysis tool. The resulting product will be a user-friendly software package that uses as-drawn fiber properties as inputs and provides predictions of the time-dependent kinetics, pump absorption, laser light propagation, and thermal field along the fiber. During Phase I, we developed a first prototype of a high-fidelity laser analysis tool to incorporate experimentally observed distributions of fiber refractive index and doping, and we performed parametric sensitivity analyses. In Phase II, we will implement upgraded physical models and numerical methods and deliver a user-friendly software package. We will validate and verify the software through comparisons to selected literature results, reduced-order models, and experimental data. Approved for Public Release | 20-MDA-10643 (3 Dec 20)