PREPARATION AND OPTICAL-PROPERTIES OF GOLD-DISPERSED BATIO3 THIN-FILMS

Gold-dispersed BaTiO3 thin films and gold-dispersed SiO2 thin films we re prepared by r.f. magnetron sputtering method. The as-deposited film s were heat-treated in air at temperature ranging from 700 to 900-degr ees-C for 1h, and were compared to the optical properties of these fil ms. For the SiO2 matrix, an absorption peak position shifted toward lo nger wavelength from 520 to 535 nm as the volume fraction of gold incr eases, and gold fine particles were spherical and were uniformly dispe rsed in the films. In contrast, for the BaTiO3 matrix, an absorption p eak position shifted from 580 to 640 run. The matrix had substantially crystallized, and the size of matrix grain and the gold particle size varied widely. The nonlinear optical property of these thin films was measured by the degenerate four-wave mixing (DFWM) method using a fre quency-doubled Nd : YAG laser with 7 ns pulse duration. Third-order no nlinear susceptibility chi(3) of gold-dispersed BaTiO3 films increased with increasing the heat-treating temperature, volume fraction of gol d in these films and the mean particle size of gold. The values of chi (3)/alpha532 Of BaTiO3 films were much larger than those Of SiO2 films . It seemed that BaTiO3 matrix contributes to increase the value of ch i(3)/alpha532. The resulting maximum value of gold-dispersed BaTiO3 fi lms was 3 x 10(-6) esu. The large chi(3) may be ascribed to the high d ielectric constant of the films.