Bio-inspired surface aberration mitigation technique for high-frequency conversion efficiency of large-aperture nonlinear optics

Low-frequency conversion efficiency severely limits the 3ω ultraviolet energy density at the target of inertial confinement fusion facilities. Here, we present a bio-inspired surface aberration mitigation (SAM) technique that could significantly reduce the crystal surface aberration and realize high frequency conversion efficiency over a clear aperture of 400 mm × 400 mm. Numerical models are utilized to optimize and verify the mechanical properties and physical performance of the SAM technique. In addition, the influences of various operation conditions on surface aberration, angle-detuning magnitude, and frequency conversion efficiency are illustrated. Finally, the process stability and online feasibility of this new approach are validated by the established offline characterization system and in situ imaging system.