Ultrashort laser pulses and ultrashort electron bunches generated in relativistic laser-plasma interaction

An experimental study of the interaction of ultrashort laser pulses with underdense plasmas in the relativistic regime is presented. A parameter regime of particular interest was found: the so-called bubble regime. In this regime, the laser pulse is focused to relativistic intensities and its pulse duration is comparable to or shorter than the plasma period. A wealth of physical phenomena occurs for such physical parameters. These phenomena have multiple signatures which have been investigated experimentally: (i) the generation of a high quality electron beam (high energy, very collimated, quasimonoenergetic energy distribution); (ii) the laser pulse temporal shortening in nonlinear plasma waves. In addition, experimental results suggest that the electron beam produced in this way has temporal structures shorter than 50 fs. (c) 2006 American Institute of Physics.