Optical nonlinearity of ZnO composite nanoparticles with different interfacial chemical environments

Abstract

This chapter reports that under proper thermal treatment, surface modification of ZnO nanoparticles with surfactant molecules result in the formation of a new ZnO-surfactant composite nanoparticles. The large and fast optical nonlinearity below band-gap occurring in these new organic-inorganic composite nanoparticles were examined by Z-scan and pump-probe technique. The sign and magnitude of both the real and imaginary parts of the third-order optical nonlinearity χ(3) of these ZnO composite nanoparticles with different chemical environments were measured by a single-beam Z-scan technique using 790 nm, 85 fs duration laser pulse. The ultrafast nonlinear response time, measured by time resolved pump-probe technique at excitation wavelength of 647 nm, suggest that the optical nonlinearity below band-gap originate mainly from a rapid electronic polarization process or virtual process such as the optical-stark effect.