Guiding femtosecond high-intensity high-contrast laser pulses by copper capillaries

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Propagation of high-intensity, high-contrast (<10⁻⁸), 50fs laser pulses through triangilar copper capillaries is experimentally studied. The relative transmission through 20-mm-long, about 50μm wide capillaries is directly measured to be 70% for input intensities up to 10¹⁷W/cm². The copper reflectivity in vacuum, helium, and air is measured in the intensity range of 10¹⁰--10¹⁷W/cm². No reflectivity decrease in vacuum and helium is observed, which leads to the conclusion that copper capillary waveguides can efficiently guide laser pulses of intensities up to 10¹⁹W/cm² on the capillary axis (that corresponds to 10¹⁷W/cm² on the walls). The reduction of the transmission efficiency to zero after a number of transmitted pulses is observed, which is caused by plug formation inside the capillary. The dependence of the capillary lifetime on the pulse energy is measured.