Coherent four-wave mixing in a laser-preproduced plasma: Optical frequency conversion and two-dimensional mapping of atoms and ions

We discuss applications of coherent four-wave mixing in the plasma of optical breakdown produced by an additional laser pulse (laser-preproduced plasma) for the generation of short-wavelength radiation and the investigation of spatial distribution of atoms and ions. The use of an additional laser for the generation of laser-produced plasma on the surface of a metal target makes it possible to optimize the efficiency of frequency conversion and to implement plasma diagnostics at various stages of plasma expansion. An experimental technique based on hyper-Raman-resonant four-wave mixing is developed for two-dimensional mapping of relative populations of excited atomic and ionic states in laser-produced plasma.