title: All-optical suppression of relativistic self-focusing of laser beams in plasmas.
abstract: It is demonstrated that a catastrophic relativistic self-focusing (RSF) of a high-power laser pulse can be prevented all-optically by a second, much weaker, copropagating pulse. RSF suppression occurs when the difference frequency of the pulses slightly exceeds the electron plasma frequency. The mutual defocusing is caused by the three-dimensional electron density perturbation driven by the laser beat wave slightly above the plasma resonance. A bienvelope model describing the early stage of the mutual defocusing is derived and analyzed. Later stages, characterized by the presence of a strong electromagnetic cascade, are investigated numerically. Stable propagation of the laser pulse with weakly varying spot size and peak amplitude over several Rayleigh lengths is predicted.
authors.affiliation: The Department of Physics and Institute for Fusion Studies, The University of Texas at Austin, One University Station C1500, Austin, Texas 78712, USA. kalmykov@physics.utexas.edu
authors.forename: S Yu
authors.initials: SY
authors.lastname: Kalmykov
authors.forename: S Austin
authors.initials: SA
authors.lastname: Yi
authors.forename: G
authors.initials: G
authors.lastname: Shvets