High precision thermal healing of large aperture crystal optics in ultrahigh energy lasers via laser–solid–thermal–fluid multiphysics

In inertial confinement fusion (ICF) device, large aperture frequency doubling crystal with uniform temperature distribution is the key to obtaining ultrahigh energy laser output under noncritical phase matching (NCPM) conditions. To address the challenge of significant temperature rise caused by the absorption of laser energy by frequency doubling crystal under ultrahigh energy laser irradiation, which restricts the efficient energy output of the device, this study focused on the multiphysics coupling mechanism and thermal healing modeling of large aperture frequency doubling crystal under service conditions. Firstly, the optical model of the crystal component was analyzed to establish the laser-solid-thermal-fluid coupling model of the crystal component under laser irradiation, revealing the generation and mechanism of the temperature field under the coupling of multiphysical field. Secondly, based on the service temperature characteristics and heat transfer mechanism of crystal, a high precision thermal healing scheme for crystal component was proposed, and a rapid recovery method for uniform temperature distribution of crystal was obtained. The results show that forced convective heat transfer reduces the temperature difference on the crystal surface to 0.02 °C. Compared with 0.08 °C of the basic model, the control accuracy is improved by 75 %. Meanwhile, the frequency doubling conversion efficiency has been increased to 88 %, representing a breakthrough in thermal management precision for nonlinear crystals. This study constructs a high precision thermal healing model under multiphysics coupling for large aperture crystal component, enhances laser frequency doubling conversion efficiency, reveals the heat transfer mechanisms under ultrahigh energy laser conditions, and provides important insights for improving laser system performance and advancing laser technology.