BACKSCATTERED SUPERCONTINUUM EMISSION FROM HIGH-INTENSITY LASER-PLASMA INTERACTIONS

We performed high-intensity subpicosecond laser-plasma interaction exp eriments to examine nonlinear scattering mechanisms in underdense plas mas. At incident laser intensities of 2 x 10(18) W/cm(2) the stimulate d-Raman-backscattered spectrum exhibited an extremely broad, supercont inuumlike structure (Delta omega/omega(0) > 1) extending from similar to 500 to >1200 nm (limited only by detector sensitivity). Large-ampli tude modulations in the spectrum of the backscattered light were measu red and are attributed to an interaction of the stimulated-Raman-scatt ered radiation with ion plasma waves. (C) 1996 Optical Society of Amer ica