Tunable optical nonlinearity of Au-TiO2 nanocomposites

The present work is focused on the correlation studies of Fermi energy level and optical nonlinearity of Au-TiO2 nanocomposites. The Fermi energy and optical nonlinearity arc found to be nearly proportionally related with respect to concentration of Au. The observed shift in Fermi level with increasing concentration of Au is due to charge transfer between TiO2 and Au in the presence of ultraviolet light irradiation during the formation of Au-TiO2 nanocomposites. The estimated third order optical nonlinearity was found to increase from 3.80 x 10(-6) to 9.69 x 10(-6) esu with increase in Au concentrations from 0 to 1.0 x 10(-2) M. This observed increment in nonlinearity is due to the enhancement of local electric field created by excitation of surface plasmon resonance that affects the Fermi energy level or work function.