Few-moded ultralarge mode area chalcogenide photonic crystal fiber for mid-infrared high power applications.

We demonstrate a novel few-moded ultralarge mode area chalcogenide glass photonic crystal fiber for mid-infrared high power applications. The numerical simulation indicates that the fiber has ultralarge mode areas of ∼10500 µm2 and ∼12000 µm2 for the fundamental mode LP01 and the lowest higher-order mode LP11, respectively. Dual-moded operation is confirmed experimentally at 2 µm, in good agreement with the numerical simulation. By selectively launching technique, low bending loss of 0.7 dB/m, equivalent to 0.55 dB/turn, has been observed in the fiber with a small bending radius of ∼12 cm, indicating excellent bending resistance of the few-moded fiber with such a large mode area. The fiber has been demonstrated to sustain an incident power density up to 150 kW/cm2 under 2-µm CW laser irradiation, showing the potential of the fiber for high-power applications in mid-infrared.