Design and high power operation of a stress-induced single-polarization single-transverse mode LMA Yb-doped photonic crystal fiber

Photonic crystal fibers consisting of a solid fused silica core surrounded by a regular array of sub-micron air-holes have been shown to operate with single mode core well above 30 ?m in active laser geometries as well as passive beam delivery fibers. Novel designs based on the combination of stress applying elements that are index matched to the holey cladding have recently been emerged. In this report we summarize the properties of these polarization maintaining photonic crystal fibers. Beside the characterization of the polarizing window and birefringence, high power laser and amplifier configurations using these fibers are demonstrated and first experiments concerning the temperature sensitivity of the polarizing properties are presented.