Time-resolved VUV reflection spectroscopy as an approach to electronic excitation dynamics of solid in intense laser fields

Itakura, Ryuji; Kumada, Takayuki   ; Nakano, Motoyoshi*; Akagi, Hiroshi

When solid material is irradiated with an intense laser pulse, a number of electrons are excited to move freely. If the density of free electrons in the solid exceeds the critical density, the excited solid exhibits high reflectivity as a plasma mirror. In order to monitor electronic excitation dynamics, we have developed a time-resolved reflection spectrometer in the VUV range. Using an algorithm of frequency-resolved optical gating, we can obtain the time-resolved reflectivity of fused silica irradiated with an intense NIR pulse as well as the temporal waveform of a VUV probe pulse.