From single-cycle self-compressed filaments to isolated attosecond pulses in noble gases

We investigate numerically the recently proposed technique of pulse self-compression by filamentation in noble gases. We show that propagation of a 30 fs infrared pulse containing a few mJ of energy leads to a few-cycle pulse in xenon, krypton, argon, and neon. We describe the different mechanisms and stages of self-compression in the different gases and show that neon, with the highest ionization potential, allows compression to the shortest durations and highest peak intensities. We discuss the process by which an unavoidable frequency modulation of the self-compressed filament simultaneously allows the generation of isolated attosecond (as) pulses via high-order harmonic generation and limits the conversion efficiency of the as pulses.