Abstract
Multi-core fibers are a technology currently at the forefront of research due to the increasing need for efficient transport of high-power continuous and pulsed laser beams [1], Power scaling is gained by propagating independent beams through spatial multiplexing in different cores to avoid thermal instability issues [2], shifting the traditional trade-off involved in enlarging the mode area while preserving single-mode operation. Phase difference compensation between the various beams is achieved by a piezo mirror system, and experimental results show that onset of multi-modality in heated cores is one of the main causes of efficiency reduction [2].