4-fold increase of the mode instability threshold in an Ybdoped multi-core fiber amplifier emitting 536 W

The scaling of the average output power of a single fiber laser emitting diffraction-limited beam-quality is limited by the onset of mode instabilities. The combination of several emitters working below their mode instability threshold is an efficient way around this challenge. In this contribution a robust and compact setup is presented, which employs a multicore fiber with four signal cores. An average output power of 536 W has been extracted, which constitutes a fourfold higher power than possible from a single-core emission of the same fiber, hence, the mode instability threshold of the system scales linearly with the number of cores.