Ionization Gating for the Generation of Tunable XUV Radiation and Isolated Attosecond Pulses

Few-optical-cycle pulses with high-peak intensity and controlled electric field can be used for the generation of isolated attosecond pulses, employing the ionization gating technique. The temporal reshaping of the electric field of the driving pulses, induced by propagation in a highly ionized gas cell, can be used to control the electron quantum paths, which contribute to the process of high-order harmonic generation. The peculiar effects produced on the generation process by temporal reshaping of the driving field, are investigated by using the nonadiabatic saddle-point method. In particular, a complete spectral tunability of the harmonic emission is understood upon considering the effects of driving pulse distortions on the phase of the relevant electron quantum paths.