Single-polarization large-mode-area Yb-doped photonic crystal fiber

We report on an ytterbium-doped, single-polarization, single-mode large-mode-area rod-type photonic crystal fiber. The active core possesses a diameter of 70 mum and a single-polarization window ranging from 1030 to 1090 nm. In a laser experiment without any intracavity polarization control up to 163 W of output power are obtained, with a degree of polarization better than 85% and a M
²
-value of 1.2.