Effects of deposition temperature on optical properties and damage characteristics of TiO₂ thin films

Titanium dioxide (TiO₂) thin films hold significant application value in fields such as optical communications and laser technology. In this study, TiO₂ thin films were prepared by ion source-assisted electron beam evaporation, and the effects of deposition temperature (T_dep) and annealing treatment on the film structure, optical properties, and laser-induced damage threshold (LIDT) were systematically investigated. The results indicate that increased deposition temperature progressively transforms the crystalline structure from amorphous to rutile phase, ultimately forming a mixed-phase structure of coexisting rutile and anatase. Films deposited at 180 ℃ exhibit the largest surface undulation and the highest roughness. The absorption coefficient and refractive index of the films show a trend of first increasing and then decreasing with the increase of deposition temperature, reaching the maximum at 180 ℃, while the transmittance decreases. Following annealing, all films demonstrate increased surface roughness along with reduced absorption coefficients and transmittance. Crystalline films possess a higher LIDT under 355 nm laser irradiation compared to amorphous films.