Raman scattering of a laser beam carrying an orbital angular momentum

Abstract

We study theoretically and numerically the Raman backscattering process of a laser beam carrying an orbital angular momentum. By expanding the electromagnetic and electrostatic waves over the Laguerre–Gauss modes, we retrieve the strong dependence of the growth rate on the radial overlap of these functions. The presence of an orbital angular momentum in the laser beam results in a mitigation of the Raman backscattering by 30%. This is confirmed with three-dimensional particle-in-cell simulations. Both the theoretical description and numerical analysis show that the scattered electromagnetic wave is generated with an azimuthal order equal to the laser beam's.