Studies on Laser Pulse Propagation

Propagation in a medium of a coherent optical wave packet whose longitudinal and transverse sizes are both of a few wavelength and whose field amplitude can induce relativistic motion of electrons is a novel challenging topic to be investigated in the general field of the so-called relativistic optics [11]. Theory and simulation have been applied to this problem for a few decades. A number of experiments have been performed since ultrashort intense laser pulses became available in many laboratories. 

In general, it has to be noticed that data from experiments have to be compared with data from numerical simulation with great care and prudence. As a matter of fact, most of the numerical codes describe propagation of the ultrashort laser pulse (1) without any pre-pulse and (2) in a medium already ionized. These two conditions are usually far from being fulfilled in a real experiment. In the following, we will show how precursors of the main laser pulse and ionization of the medium can deeply change the propagation of an ultrashort intense laser pulse. 

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