We present the z-scan studies of low-excited laser plasma showing a self-interaction of a femtosecond beam during the high-order harmonic generation in the laser plumes produced on the surfaces of different targets. This process was attributed to the ionization of neutrals and singly charged ions at the leading part of the laser pulse with further self-defocusing caused by the free electrons. The spatial distribution of the radiation propagating through the plasma showed an appearance of a ringlike shape at the intensities exceeding the barrier suppression intensity for singly charged ions. We show that this process leads to the restriction of the cutoff energy of high harmonics and the conversion efficiency from laser plasma.
© 2006 Optical Society of America
Original Manuscript: September 22, 2005
Revised Manuscript: February 26, 2006
Manuscript Accepted: March 3, 2006
Rashid A. Ganeev, Motoyoshi Baba, Masayuki Suzuki, and Hiroto Kuroda, "Analysis of nonlinear self-interaction of femtosecond pulses during high-order harmonic generation in laser-produced plasma," J. Opt. Soc. Am. B 23, 1332-1337 (2006)