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/sup 18/ W/cm/sup 2/, these pulses have a pressure greater than 10/sup 3/ Mbar creating large density oscillations and relativistic electron velocities at the surface. This results in efficient odd harmonic generation. The author present is a physical model for this harmonic generation mechanism, along with 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.>