Optical transition process in AgO_x super-resolution near-field structure

A sandwiched 15 nm AgO_x thin film of the super-resolution, near-field optical disk was studied using a confocal Z-scan system. Nonlinear optical properties of quartz glass/ZnS-SiO₂ (170 nm)/AgO_x (15 nm)/ZnS-SiO₂ (40 nm) were measured using a Q-switch Nd:YAG pulse laser of wavelength 532 nm, pulse width 0.7 ns, and 15.79 kHz repetition rate. Transmittance and reflectance of the sandwiched AgO_x thin film show important optical responses at the focused position of Z-scan. The dissociation processes of AGO_x, recombination of the silver and oxygen, and the resonance of the localized surface plasmon of the nano-composites of the AgO_x thin film are correlated to transmittance and reflectance at the focused position of the Z-scan for different input laser powers. An irreversible upper threshold intensity of 4.40 × 10⁶ mW cm^-2 at the focused position was found. A reversible working window of the focusing intensity between 1.86 × 10⁶ and 4.40 × 10⁶ mW cm^-2 was measured with sandwiched AgO_x thin film alone. The near-field interactions of the AgO_x thin film and the recording layers of super-resolution near-field optical disk are also discussed.