Ensemble effect of intrinsic defects and Mn ions on the enhancement of third order nonlinearity of ZnO nanoparticles

Abstract

Mn doped ZnO nanoparticles were synthesized by the chemical co-precipitation method and XRD confirms the hexagonal structure of nanoparticles with good crystallinity. From TEM analysis, the average crystallite size of the nanoparticles is evaluated as 7-13 nm. All the prepared nanoparticles exhibit reverse saturable absorption in open aperture Z-scan measurements. The experimental data best fits for two-photon absorption along with saturable absorption and the obtained β values are found to be in the range of 0.3-0.5 × 10(-10) m W(-1). The enhancement of β upon increasing Mn concentration is attributed to the increase of absorption due to defect states created by Mn doping. EPR and PL measurements provide evidence of the presence of zinc vacancy defects. The self-defocusing nonlinearity exhibited in Mn doped ZnO nanoparticles at 532 nm indicates the reverse saturable absorption (RSA) based optical limiting behavior.