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

A method of generating odd harmonics from an intense laser incident upon a sharp vacuum-overdense plasma interface is presented. One and two-dimensional simulations are used to investigate the interaction of ultra-intense laser pulses with a sharp vacuum-plasma interface. With an intensity greater than 10(18) W/cm2, these pulses have a pressure greater than 103 Mbars creating large density oscillations and relativistic electron velocities at the surface. This results in efficient odd harmonic generation. We present a physical model for this harmonic generation 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.