Effect of Coulombic expansion on the evolution characteristics of short laser pulses propagating in clustered gas

In this paper, interaction of a short, linearly polarized laser with clustered gas has been studied. Assuming the clustered gas to be tenuous, Coulombic expansion of a single nanometer sized cluster in response to a short (∼100 fs) laser pulse has been analyzed and instantaneous change in cluster radius averaged over ion time scale is evaluated. A wave equation describing the laser field evolution, driven by the polarization field arising due to the presence of the clusters, is set up. Further temporal evolution of the spot-size, pulse duration, and induced chirp of a short laser pulse has been studied, using the Lagrangian approach.