Highly polarized photonic crystal fiber laser.

We report on the design of a polarization maintaining, double-clad, Yb doped photonic crystal fiber and demonstrate its lasing properties. The polarizing properties of the fiber rely on birefringence and differential loss introduced by an anisotropic hole structure. Due to a slight leak from the core to the inner cladding only ~80% of the output light is in the core mode. We have demonstrated 2.9W of output in this mode with a polarization ratio in excess of 200:1.