Intense Isolated Short Attosecond Pulse Generation from a Coherent Superposition State in a Spatially Inhomogeneous Field

Abstract

Abstract We theoretically present an efficient method of generating an intense isolated short attosecond (as) pulse in a spatially inhomogeneous field. It is shown that this spatiotemporally combined field can significantly extend the harmonic cut-off and enhance the harmonic efficiency when the initial state is a coherent superposition of the ground and excited states. Then, a highly efficient continuum spectrum with an extremely wide bandwidth is directly generated. Due to the introduction of the spatial inhomogeneity, the short path is selected and the long one is removed; as a result, an intense isolated 17.3-as pulse is obtained straightforwardly. In addition, we also investigate the influences of the parameters including the population of the excited state, spatial inhomogeneity, carrier–envelope phase, pulse duration, and intensity on the harmonic spectrum.