Modeling and optimization of multimode fused fiber combiners

An effective method to predict the performance of multimode fused fiber combiners is presented. The realization of high power devices is strongly affected by the specific application, for instance whether used in fiber or in direct-diode lasers, and thus usually requires costly and time-consuming trial-and-error procedures. The proposed approach, which is based on ray tracing and statistical analysis, allows analyzing a-priori the impact of fiber dimensions, combiner geometry, glass material properties and laser beam quality on the coupling efficiency, therefore reducing the fabrication runs. Examples of application to 7-to-1 and 19-to-1 combiners are given and compared with experimental results.