Simulation of stimulated Raman backscatter from interaction between ultrashort, ultrahigh intensity laser and tenuous plasma

This paper studies the excitation of the stimulated Raman backscatter of ultrashort and ultrahigh intensity laser pulse. Through one dimentional particle-in-cell code LPIC++, it is found that in the relativitic condition, the stimulated Raman backscatter is not in the mormal mode but strongly coupled. The frequency spectra become broad with blueshift and the interval between the peaks are greater than the frequency of the plasma wave frequency. These results are consistent with the prediction of a srongly coupled Raman theory.