The effect of mutual off-centered launch of a SM fiber into a few-modes fiber, on the output beam quality

摘要

Beam quality analysis of mutual off-centered fibers is presented. The relevant scenario is where a single mode input fiber is injecting optical radiation into a few-mode output fiber. Both are step-index, single clad fibers. Assuming the source's coherence time is short enough, the major finding is that the output beam quality is the highest when the injecting fiber is at some offset with respect to the center of the receiving core. A Theoretical analysis and an experiment are in good agreement with each other. These results may have practical consequences in beam-coupling schemes and in applications emphasizing the importance of beam quality.