Optical nonlinearity and optical limiting of CdSeS/ZnS quantum dots

摘要

CdSeS/ZnS quantum dots (QDs) were synthesized through the chemical route. The optical limiting behavior of these QDs was observed. The quantum dots' nonlinear absorption and nonlinear refraction were investigated by the Z-scan technique using a Nd:YAG laser second-harmonic radiation (lambda = 532 nm, t = 35 ps). Based on the absorption and fluorescence spectra, it is reasonable for us to infer that the nonlinear absorption arises from free carrier absorption (FCA). These QDs have average absorption cross-section of 1.26 x 10(-16) cm(2) and nonlinear refractive index in the order of 10(-8) esu. The large nonlinear absorption perhaps allows them to be candidate material for the optical limiting devices.