Ultrafast optical characteristics of Mn-doped CdS quantum dots

Abstract

Cadmium sulfide (CdS) quantum dots (QDs) doped with different concentrations of manganese (Mn = 0, 1, 3, 5, and 7 %) are synthesized via thermolysis of diselenocarbamato complexes of cadmium in the trioctylphosphine oxide (TOPO). The QDs show quantum size effects in the optical spectra and exhibit band-edge emission. The TEM images revealed that the QDs are spherical within the range of 3 to 5 nm. The nonlinear optical studies and optical limiting characteristics are studied. From open and closed aperture data, the nonlinear absorption coefficient (β) and refractive indices (n2) values are found to be in the range of 4–16 x10-9 cm2/w and 8-14x10-15 cm2/w. The cross relaxations and energy transfer mechanism of quantum dots are studied using the transient absorption pump–probe experiment.

Keywords

• Quantum dots
• Nonlinear optical studies
• Relaxation dynamics
• Cadmium sulfide