摘要

We propose a method to generate broadband supercontinuum with a modulated polarization gating in the multi-cycle regime. The polarization gating at 1600 nm is employed to intensify the ellipticity dependence of high harmonic signal, and the adding second harmonic (SH) field is used for modulating ionization ratio between the driving field half-cycles. It is shown that longer driving pulses ( 6 optical cycles, 32.4 fs) can be applied to confine the efficient recollision of electron wave packet to half an optical cycle. The produced bandwidth of the extreme ultraviolet (XUV) supercontinuum is about 280 eV, corresponding to a fourier-transform-limited pulse of 10 as. In addition, an attosecond pulse of about 100 as with tunable wavelength can be straightforwardly obtained just by filtering different range of the spectrum.