NONRESONANT OPTICAL NONLINEARITIES OF SURFACE CHEMICALLY-MODIFIED ZNOCOMPOSITE NANOPARTICLES

With surface chemical modification, we have obtained core-shell struct ure ZnO nanoparticles. The nonresonant third-order nonlinear optical r etraction of this new composite material was found to be -3.8 x 10(-10 ) esu by Z-scan measurements with a femtosecond pulsed laser. The ultr afast nonlinear response time similar to 250 fs measured by time-resol ved pump-probe techniques suggests that the nonlinearity of this new m aterial originates mainly from a rapid electronic polarization process or virtual process such as the optical Stark effect.