ODD HARMONIC-GENERATION OF ULTRA-INTENSE LASER-PULSES REFLECTED FROM AN OVERDENSE PLASMA

A method of generating odd harmonics from an intense laser incident up on a sharp vacuum-overdense plasma interface is presented. One and two -dimensional simulations are used to investigate the interaction of ul tra-intense laser pulses with a sharp vacuum-plasma interface. With an intensity greater than 10(18) W/cm2, these pulses have a pressure gre ater than 103 Mbars creating large density oscillations and relativist ic electron velocities at the surface. This results in efficient odd h armonic generation. We present a physical model for this harmonic gene ration mechanism, and some scaling of the power in the third harmonic. This is compared with relativistic particle-in-cell simulations that include mobile and immobile ions, as well as a variety of upper shelf densities. A discussion on how ion profile modifications influence the harmonics is also presented.