TiO2/SiO2dielectric film damage induced by combination of pulsed and continuous wave infrared laser irradiation

This paper describes the combined irradiation effect of 2.7μm pulsed and 10.6μm continuous wave (CW) lasers on TiO2/SiO2 dielectric films. There were four combined irradiation time sequences, two of which were irradiation one after another and two were irradiation overlap. Single laser irradiation on the films was also carried out for analyzing the different results. The transmission spectrums of the films in visible and NIR region were measured before and after laser irradiation, which was taken as one of the measures of the damage degree. Typical damage morphologies under different conditions and the standing electromagnetic wave field of two laser wavelengths in the film samples were given. Comparing the irradiation results of different time sequences, especially when the pulsed laser ahead or behind of CW laser, conclusion can be drawn that the overlap of pulsed and CW laser had the most serious damage degree of the films.