Proposal for single attosecond pulse production with a 43 fs super intense laser pulse

High harmonics generation (HHG) from Ne atom driven by a multi-cycle 43 fs laser pulse is investigated. The numerical simulation demonstrates that when the intensity of the driving laser is over-saturated, the atom will be ionized rapidly during a few optical cycles, this will lead to a continuous multi-plateau structure in the cutoff region of the high harmonics spectrum from the neutral atom. It is also shown that the signal of high-order harmonics from the ion becomes remarkable when the driving laser is super intense. The superposition of an appropriate sub-plateau can give single attosecond soft X-ray pulse, and the effect of HHG from ion has been eliminated through the band selection.