Third-order optical nonlinearities of sol-gel-processed Au-SiO2 thin films in the surface plasmon absorption region

Abstract

Nanometer-sized gold particles were prepared in thin-film silica glass by sol-gel processing and their third-order nonlinear optical properties were characterized in the surface plasmon absorption region (530-570 nm), employing the self-diffracted degenerate four-wave mixing (DFWM) technique. The Au-SiO2 thin films contained 0.73% of Au nanocrystals in volume fraction and the particle diameter was estimated to be ca. 10 nm. By the nanosecond DFWM measurement, the thermo-optical nonlinear optical coefficient χ(3) was obtained as (0.4-2.3) × 10-8 esu in which the largest value occurred near the surface plasmon frequency.