Multimode Optical Fiber Beam-By-Beam Cleanup
Mario Ferraro, Fabio Mangini, Yann Leventoux, Alessandro Tonello, Mario Zitelli, Tigran Mansuryan, Yifan Sun, Sébastien Février, Katarzyna Krupa, D. S. Kharenko, S. Wabnitz, Vincent Couderc
Abstract
We introduce and experimentally demonstrate the concept of all-optical beam switching in graded-index multimode optical fibers. Nonlinear coupling between orthogonally polarized seed and signal beams permits to control the spatial beam quality at the fiber output. Remarkably, we show that even a few-mode control beam whose power is about ten times lower than that of the total beam may substantially enhance the quality of an intense, highly multimode signal beam. We propose a simple geometrical representation of the beam switching operation, whose validity is quantitatively confirmed by the experimental mode decomposition of the output beam. All-optical switching of multimode beams may find important applications in high-power beam delivery and fiber lasers.