Spectrally Resolved Nonlinear Optical Properties Of Colloidal Quantum Confined Semiconductor Dots, Rods And Nanoplatelets

Abstract

Extended Abstract Semiconductor nanomaterials with dimensions close to the exciton Bohr radius have received great attention over recent years, owing to their unique physical and chemical properties [1]. Luminescent quantum dots (QDs) are ideal luminophores for multiplexed optical coding because their fluorescence emission band position can be continuously tuned by changing the particle size. The absorption and emission spectra are regarded as properties of the material and are normally independent of the light intensity. However, for sufficiently large light intensities, such as those available with femtosecond lasers, these optical characteristics additionally become functions of the light intensity. The quantum confinement and dielectric confinement effects make these materials a promising class of third-order nonlinear optical (NLO) media with large third-order nonlinear susceptibilities and a fast response time. The colloidal syntheses presented here allow the fabrication of morphology well-defined, monodisperse in size semiconductor QDs, QRs, or quantum nanoplatelets (NPLs). In the literature current studies are primarily the NLO properties measured usually at a single wavelength. We studied the nonlinear optical (NLO) properties of several quantum-confined semiconductors with various morphologies, i.e. quantum QDs, QRs and NPLs. The NLO properties of the samples were measured by the Z-scan and two-photon excited emission (TPEE) techniques using a femtosecond laser system in a wide spectra range. Here, we show the NLO factors in a wide wavelength range to find maximal values of the parameters