Mixed oxide coatings for advanced fs-laser applications

A modified IBS-process was used to create mixtures of oxide coating materials. The process allows to manufacture new designs, whereas the important optical and electronic properties of the material can be varied in a wide range. Especially for ultra short pulse applications, higher damage thresholds can be achieved. In this paper, LIDT measurements of mixed and pure single layers are presented. The coatings were investigated at different wavelengths and in a wide pulse duration range. The results of the measurements confirm the empirical law of the linear LIDT dependency on the absorption gap. Based on this empirical law, the Refractive Index StEps Down (RISED) concept was developed. From the data of the single layer measurements, an optimization of RISED optical components in the fs-regime will lead to even higher damage thresholds. Particularly, for high reflecting mirrors the damage threshold could be doubled for different dielectric coating materials. Additionally, the paper presents a theoretical analysis of the stack LIDT on the basis of the single layer properties.