Electromagnetic solitary waves in the saturation regime of stimulated Brillouin backscattering

Recent particle-in-cell simulations of the stimulated Brillouin backscattering (SBBS) of electromagnetic radiation have shown that even at sub-relativistic intensities (Iλ² = 10¹⁶ W μm²/cm²) non-drifting solitary waves, "solitons" for short, are easily produced, and remain almost unchanged all along the simulation time, typically for several thousands of optical cycles. They appear in the form of stable local concentrations of electromagnetic radiation trapped inside quasi-neutral density holes. The plasma density inhomogeneity associated with their presence disrupts the resonant SBBS amplification. The cavitation process is accompanied by strong electron and ion heating. The physical characteristics of such solitons are discussed and they are compared with the theoretical predictions of an analytical model for localized solution of the Maxwell equations in warm plasma.