Optical features of noble-metal-oxide thin films under irradiation of blue laser.

The optical reflectance and transmittance of Platinum oxide (PtO(x)) and palladium oxide (PdO(x)) thin films for ultrahigh-density optical storage are investigated using Z-scan technique under irradiation of blue laser (442 nm). The power thresholds of the PtO(x) and PdO(x) decomposition, 3.1 mW and 2.6 mW, are obtained respectively; the PtO(x) (PdO(x)) thin film is reversible and irreversible when input power is less than and more than 3.1 mW (2.6 mW). Deformation analyses by using an atom force microscope (AFM), which is formed in the micro irradiation region of surface on the thin film samples due to decomposition of the PtO(x) or PdO(x) driving the Z-scan, agree well with the Z-scan results. The optical features obtained at 442-nm wavelength are compared with those at 532-nm wavelength, and the threshold difference between the two wavelengths is also analysed in detail based on wavelength-dependent average power density and wavelength-selected absorption of the thin films.