Control of high-order harmonics from H2+ and D2+ for producing intense single attosecond pulse

Generally, the intensities of molecular high-order harmonic spectra from H-2(+) and its isotope molecules are quite different due to the effect of nuclear signals. Thus, in this paper, we investigate the change law of harmonic spectra from H-2(+) and D-2(+) driven by different laser fields and try to find the optimal harmonic spectra for producing intense single attosecond pulses (SAPs). The results show that in lower laser intensity case, the harmonic yield follows as H-2(+ )> D-2(+); while, in higher laser intensity case, the harmonic yield meets the condition of D-2(+) > H-2(+). Further, by using this change law of harmonic yield and choosing the optimal harmonic emission peak (HEP), we can obtain the intense spectral continuum with the assistance of the half-cycle pulse (HCP). Next, with the superposition of some harmonics on the spectral continuum, the intense SAPs shorter than 37 as can be obtained from H-2(+) and D-2(+) harmonic spectra. Finally, the results show that the stronger attosecond signals can be obtained when the light nucleus or heavy nucleus molecules are driven by lower or higher laser intensities, respectively.