Optical nonlinearity of nanocrystalline Au/ZnO composite films.
The third-order nonlinear optical susceptibilities, chi(3), of composite films consisting of nanocrystalline Au and ZnO particles were investigated by use of a degenerate four-wave mixing scheme. The maximum value of chi(3), measured at a laser wavelength of 532 nm and a pulse duration of 70 ps, was approximately 2 x 10(-6) esu. Also, this chi(3) value was achieved with small absorption (the surface-plasmon peak was at the 615-nm wavelength). Our composite materials showed no discernible degradation after they were subjected to irradiation for a total of 3 x 10(7) high-intensity pulses (24 Mw/cm2, 70-ps pulse duration at 500 Hz) during 16 h of testing.