Laser intensification by spherical inclusions embedded within multilayer coatings

The initiation of laser damage within optical coatings can be better understood by electric-field modeling of coating defects. The result of this modeling shows that light intensification as large as 24× can occur owing to these coating defects. Light intensification tends to increase with inclusion diameter. Defects irradiated over a range of incident angles from 0 to 60 deg tend to have a higher light intensification at a 45 deg incidence. Irradiation wavelength has a significant effect on light intensification within the defect and the multilayer. Finally, shallow, or in the case of 45 deg irradiation, deeply embedded inclusions tend to have the highest light intensification.