Emergent slowly rotating polarization state suppresses cross beam energy transfer in laser driven fusion plasmas

Cross-beam energy transfer (CBET) between intersecting laser beams remains a major challenge for controlling energy deposition in inertial confinement fusion (ICF) plasmas. Here we show that polarization dynamics can suppress CBET. When two laser beams cross in an inhomogeneous, expanding plasma, the local polarization in the overlap region evolves into a slowly rotating polarization that inhibits stimulated scattering responsible for beam-to-beam energy exchange. We show that this regime can be realized using state-of-the-art lasers with sufficiently narrow bandwidth. Two-dimensional simulations and Stokes-parameter analysis reveal the emergence of a linear slowly rotating polarization (SRP) during the interaction. The mechanism operates for both side and back scattering CBET geometries and remains effective at intensities relevant to modern fusion-class laser systems, providing a route to control laser-plasma coupling in direct-drive ICF.