NONLINEAR OPTICAL PROPERTIES OF DOPED <font>ZnS</font> QUANTUM DOTS

Abstract

Three- and four-photon nonlinear absorptions are reported by z-scan techniques in ZnS and 1% Mn 2+ doped ZnS quantum dots (QDs) with 532 and 1064 nm radiations, respectively, obtained from a Q-switched Nd :YAG laser fundamental and its second harmonic radiation. The obtained maximum value of the 3PA coefficient in the doped ZnS QDs is ~10 5 times that of bulk ZnS . Also, intensity-dependent saturation of 3PA has been observed and the measured experimental data are explained theoretically using a 3PA saturation model and the characteristic saturation intensity is estimated to be 0.92±0.04 GW/cm 2 .