Emergent Slowly Rotating Polarization State Suppresses Cross Beam Energy Transfer in Laser Driven Fusion Plasmas
Image : Laser beams crossing in inhomogeneous expanding fusion plasma
Original source: nature.com, Aug 22 , 2026. Click here for the article link
Abstract
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.
Image : Generation of linear slowly rotating polarization (SRP, green) through the overlap of left (red) and right (blue) circularly polarized laser beams.
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Blue Laser Fusion, Inc (BLF) is commercializing a proprietary and novel pulsed laser architecture based on its high peak power, efficient, reliable and cost-effective laser optical enhancement cavity (OEC) technology. BLF is pursuing pulsed laser applications in directed energy defense to neutralize advanced threats with instant engagement of targets at the speed of light, with a deep magazine and low cost per shot compared to conventional approaches. Additionally, the company is developing GW scale, safe, secure, clean fusion energy based the proven ignition and gain demonstrated by LLNL NIF in 2022 in order to power economic growth and meet the acute and increasing demand for data centers & Al, EVs, and on-shored manufacturing. BLF has a comprehensive IP portfolio with more than 120 patents and applications internationally. Blue Laser Fusion is based in Santa Barbara, CA with additional operations in Japan.
