Effects of oxygen flows on optical properties, micro-structure and residual stress of Ta2O5 films deposited by DIBS

High precision optical components, such as ultra-high reflectors, severely suffer from absorption losses. In order to get optical films with low absorption losses, many techniques, such as annealing and laser conditioning, have been widely employed as a post-deposition treatment process to deal with as-deposited films. However, the success of these processes starts with the correct choice of the deposition parameters. In this paper, Ta2O5 films are deposited by dual ion beam sputtering (DIBS) method and the effects of target oxygen flows on optical properties, microstructure and residual stress are systematically investigated. The results show that target oxygen flows can significantly affect the absorption losses and residual stress of Ta2O5 film. The XRD patterns reveal that Ta2O5 films deposited at different parameters are all amorphous. Finally, based on the results of Ta2O5 films, broadband dielectric mirror with high reflection and low absorption losses in the range from 380 nm to 750 nm is successfully fabricated.