NONLINEAR ELECTRODYNAMICS OF THE INTERACTION OF ULTRA-INTENSE LASER-PULSES WITH A THIN FOIL

An analytical description of the interaction of laser light with a foi l, described as a thin slab of overdense plasma, is presented together with the results of multidimensional particle in cell simulations. Th e matching conditions at the foil result in nonlinear boundary conditi ons for the wave equation. The conditions for relativistic transparenc y are given. The interaction with the foil leads to shaping of the las er pulse. In the case of oblique incidence of a relativistically inten se pulse, nonlinear coupling modifies the pulse polarization and cause s emission of high harmonics and generation of an electric current. St rong focalization of the reflected pulse, in particular in three-dimen sional simulations, is observed for normal and oblique incidence due t o the induced distortion of the foil surface. (C) 1998 American Instit ute of Physics. [S1070-664X(98)03507-1].