Single attosecond pulse generation with intense mid-infrared elliptically polarized laser pulses.

We have studied theoretically high-harmonic-order and single attosecond pulse generation with elliptically polarized laser pulses at wavelengths ranging from the visible to the mid-infrared. Results of ab initio simulations of the time-dependent Schrödinger equation show that the ellipticity dependence of the high-harmonic signal intensifies with increasing wavelength of the driving pulse and saturates in the mid-infrared. The isolation of single attosecond pulses using the polarization gating method in the mid-infrared is due to an effective suppression of side pulses as compared with an operation at Ti:sapphire wavelengths.