Preparation of Silver Thin Films Consisting of Nano-Sized Particles by the Evaporation-Condensation Method and Its Linear and Nonlinear Optical Properties

Abstract

Silver particles generated by the evaporation-condensation method were deposited to form a film on a silica glass substrate. The films thus obtained consist of nano-sized silver particles. Nonlinear refractive index, γ and nonlinear absorption coefficient, β determined by using Z-scan technique were both negative, while γ in the literatures for the silver particles-dispersed-glass composites was positive. The absolute value of γ for the as-deposited samples was increased as absorption peak wavelength due to surface plasmon resonance became close to the laser wavelength used in the measurement. The particle size (D) dependence, especially D^-3 dependence of γ was clearly observed for the films which were prepared at different particle generation temperatures and annealed at 170°C, and consisted of particles of 26 to 46 nm in size. This dependence was explained in terms of the quantum confinement effect.