High-Brightness High-Order Harmonic Generation by Truncated Bessel Beams in the Sub-10-fs Regime

(Received 21 June 2001; published 2 January 2002)Low-divergence, high-brightness harmonic emission has been generated by using a fundamental beamwith a truncated Bessel intensity profile. Such a beam is directly obtained by using the hollow-fibercompression technique, which indeed allows one to optimize both temporal and spatial characteristicsof the high-order harmonic generation process. This is particularly important for the applications ofradiation, where extreme temporal resolution and high brightness are required.