Quantum wave-packet exploration of isolated ultra-short attosecond pulse generation by a modified three-color laser field scheme

摘要

By numerically solving the three dimensional time-dependent Schr?dinger equation, we explore the high-order harmonic and attosecond pulse generation of He atoms exposed to a special three-color field. An ultrabroad supercontinuum with a bandwidth of 887 eV has been attained, supporting an isolated 4 as pulse straightforwardly by Fourier transforming. Utilizing available intense infrared femtosecond laser resource within the nonrelativistic regime, the produced laser pulse is near to zeptosecond region. Remarkably, the harmonic conversion efficiency is enhanced in terms of the double-plateau structure of the harmonic spectra, yielding high-intensity attosecond pulses with alternative plateau.