Nonlinear absorption and refraction of CdSe/ZnS quantum dots at two‐photon resonant excitation of excitons

Abstract

The observed nonlinear absorption, optical limiting and nonlinear refraction of colloidal CdSe/ZnS quantum dots in the case of two‐photon resonant excitation of 1S3/2(h) – 1S (e) exciton transition by powerful picosecond laser pulses have been explained by two‐photon absorption and self‐defocusing effect. The results of experiments have allowed to separate self‐defocusing effects arising due to the change of nonlinear refractive index of bound electrons and nonlinear refraction from two‐photon generated carriers. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Synthesis and Characterization of the Nonlinear Optical Properties of Novel Hybrid Organic–Inorganic Semiconductor Lead Iodide Quantum Wells and Dots

“…In that sense, only an indirect comparison can be made between the present findings and other literature reports, since different types of semiconducting QDs exhibit different NLO behavior based on their size and exciton binding energy. The most studied QDs are the CdSeS, CdS, or CdSe/ZnS. , These systems tend to exhibit strong reverse saturable absorption behavior, attributed to free carrier absorption. Nevertheless, the class of hybrid organic–inorganic materials studied in the present study was found to exhibit insignificant nonlinear absorption and strong nonlinear refraction, under all the experimental conditions employed, suggesting that these materials could be promising candidates for several applications in optoelectronics where absorption is unwanted.…”