Thermal analysis of multilayer dielectric grating with high power laser irradiation

We have established a thermal distribution model of the multilayer dielectric grating with laser irradiation based on the Beer–Lambert theory and the thermal conduction theory. The temperature change on the surface and inside of the grating is simulated according to the laser irradiation time, laser power, substrate size, and substrate material. The actual thermal behavior of a 50 × 50 × 10 mm3 multilayer dielectric grating with fused silica substrate is measured with 10 kW fiber laser irradiation. The results show a dynamic equilibrium between the energy absorbed in the laser irradiation area and the energy transferred in the thermal transfer area when the maximum temperature of the grating is kept stable. The simulation results are in good agreement with the experimental data, which provides a reference for understanding the thermal dynamics process of the multilayer dielectric grating with high power density laser irradiation.