Analysis on laser-induced transient damage behavior in multilayer coating

• The transient damage of antireflection coating under ultrashort pulses is analyzed.
• The antireflective coating, composed of ZnS and SiO2 materials, is analyzed.
• The theoretical laser-induced damage threshold can be calculated.

Based on the ionization theory and the Drude model of free electron gas, transient damage principle of the anti-reflection coating under ultrashort pulses are analyzed. Specifically, the damage of an anti-reflection coating designed by ZnS/SiO2 materials is calculated. The results show that during the irradiation process the parameters, such as the refractive index, the electric field and the free electron density, should impact on each other. The coupling relationship between these parameters causes the change in the refractive index, which further leads to the decrease of transmittance of anti-reflection coating from 0.96 to 0.01. In addition, the coupling relationship causes the repartition of free electron density constantly, which eventually leads to the external damage of anti-reflection coating.