19-cores Yb-fiber laser with mode selection for improved beam brightness

We propose a new method to control the mode combination at the output of a 19-core fiber laser in order to produce a bright beam with uniform phase. The technique is based on both the selective excitation of the amplifying multicore fiber and on an intra-cavity angular filtering at the output. The excitation of the fundamental in-phase supermode of the 19-core fiber was demonstrated, resulting in the emission of a single-mode beam with M 2 limited to 1.21.