Reflectivity of intense femtosecond laser pulses from a simple metal

Abstract

Femtosecond laser heating of a solid offers the possibility of producing plasmas with near-solid densities. Many reflectivity measurements have been made on such plasmas to probe their electrical conductivity. In particular, the experiment of Milchberg, Freeman, and Davey has been interpreted as showing a significant discrepancy between theoretical and measured conductivities. Here we present an alternative interpretation based on careful analysis of hydrodynamic expansion and the nonlocal interaction of the incident laser field. We find the experimental data to be largely consistent with theoretical models. This finding is also supported by the experiment of Fedosejevs Fedosejevs et al.