Polarization-maintaining, Ytterbium-doped, rod-type, multicore fiber

We present the first polarization-maintaining, Ytterbium-doped, rod-type, multicore fiber with 5x7 cores. This fiber is drawn from a drilled 7x7 preform in which the outermost columns were filled with Boron-doped stress-rods, resulting in a stress-field strong enough to induce linear birefringence in all the cores simultaneously. Experimentally we have observed the preservation of linear polarization in the cores, albeit to a different degree depending on the core positions.