Intensity improvement in the attosecond pulse generation with the coherent superposition initial state

摘要

We investigate the coherent superposition initial state effect and found that when the initial active electron state is prepared in the coherent superposition of the is and 2s states of the He+ ion and the chirp parameter of the fundamental field in the two-color scheme is chosen to be beta = 0.3, the harmonic cutoff energy is remarkably extended and the harmonic yield is enhanced by at least 6 orders of magnitude compared with the case of the single 1s ground state with chirp-free pulse. An ultrabroad supercontinuum with a 458 eV bandwidth is formed, directly producing an intense isolated 34 as pulse. (c) 2012 Elsevier B.V. All rights reserved.