Preparation of high laser-induced damage threshold sol-gel Nb2O5 films with different additives

•Three different types of Nb2O5 films were prepared by using NbCl5 as precursor.•The highest laser-induced damage threshold of the film was 24.9 J/cm2.•The defect-induced damage showed different types of damage features.•Structural evolution models were proposed according to the results. In this study, different sol-gel Nb2O5 films were prepared by using NbCl5 as precursor, and acetylacetone (ACAC), diethanolamine (DEA) and citric acid (CA) as additive, respectively. The results showed that the film with ACAC as additive presented the highest absorption and stability, corresponding to the lowest laser-induced damage threshold (LIDT) of 18.9 J/cm2, while that with CA as additive had the lowest absorption, corresponding to the highest LIDT of 24.9 J/cm2. The film prepared with DEA as additive had the smallest surface roughness, and the LIDT was 21.1 J/cm2. Moreover, although the films prepared with three different additives were all subjected to typically defect-induced damages, different types of damage features were observed. Finally, three structural evolution models of the films were proposed, accompanied by establishment of the relationship between the additives and the LIDT, which was of great significance to further understand the laser damage mechanism.