Abstract

Recently, high-harmonics of femtosecond laser pulses are actively utilized in time-resolved photoelectron spectroscopy and transient absorption spectroscopy for revealing ultrafast electronic dynamics of atoms and molecules. Short-wavelength pulses generated as high-harmonics are also sensitive probes into laser plasma with high density of excited electrons on the surface of solid materials, because the plasma resonance frequency is proportional to the square root of the density of excited electrons. We demonstrated that time-resolved vacuum ultraviolet (VUV) reflection spectroscopy is applicable to extraction of time-dependent reflectivity change in ultrafast plasma formation as well as to characterization of VUV pulses [1]. In this study, we turn our attention to the spatial mode of plasma mirror reflection in addition to the temporal characteristics.

© 2017 IEEE