Third order optical nonlinearities in ZnFe2O4 nanocrystals

Using Z-scan method with picosecond laser at 532 nm, the third order optical nonlinearities of ZnFe2O4 were investigated. The nonlinear refractive index is positive for all ZnFe2O4 samples and decrease with the nanocrystal size. The nonlinear absorption dominated by saturable absorption for 19 nm and 11 nm ZnFe2O4 but by two photon absorption for 5 nm ZnFe2O4 organosol. Origin of the optical nonlinearities and the size effect has been discussed.