Exploring Laser-Induced Damage Threshold in Metallic Coatings Across Fifteen-Order Magnitude Range of Pulse Lengths

We investigated the laser-induced damage threshold (LIDT) of seven metallic (Ag, Al, Au, Cr, Ta, Ti, W) and two semiconductor (Si, Ge) coatings on glass substrates as a function of the laser pulse duration using 1-on-1 and S(1000)-on-1 testing. Experiments spanning pulse durations from 10 femtoseconds to 10 seconds revealed two distinct LIDT scaling laws for pulsed and continuous-wave (CW) regimes. Numerical simulations of laser radiation coupling and heat diffusion in gold coating explained the observed scaling. They predicted the transition between pulsed and CW regimes, which depends on film thickness and material properties. For short pulses, LIDT is dominated by the metallic film, while for long pulses, heat dissipation into the substrate becomes critical. These findings enhance the understanding of LIDT scaling and the thermal dynamics of metallic coatings.