Characterization of ultraviolet femtosecond pulse propagation in aluminum-coated capillary fibers

Abstract

We demonstrate that hollow core fibers with aluminum-coated bores of ϕ=0.7mm and ϕ=1.0mm are well suited for guiding high-power ultraviolet femtosecond pulses. We consider 1-m-long fibers in two geometries: straight and bent with a 30-cm radius of curvature. The straight fibers transmit approximately 60% of the power at 200nm and 85% at 266nm, while the corresponding numbers for the bent fibers are 25% and 35%. The duration of the femtosecond pulses increases by 10% and 50% per meter at 200 and 266nm, respectively. The broadening increases to a factor of two when the fiber is bent. The maximum transmitted pulse energy at 266nm is 100μJ corresponding to 0.5GW or an intensity of 1011W∕cm2. However, this value is limited only by the 266nm pulse generation and is expected to go even higher. The applicability of the powerful femtosecond pulses from the fiber is demonstrated by an experiment in which water is ionized by two-photon absorption. This experiment indicates the potential of using aluminized hollow core fibers in medical therapy with ultraviolet femtosecond pulses.