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    Third order nonlinear investigations of CuLaSe2 and ZnCuLaSe2 quantum dots
    (Elsevier, 2023) Gundogdu, Yasemin; Cadirci, Musa; Kilic, Hamdi Sukur; Elibol, Erdem
    Environmentally friendly quantum dots (QDs) with high two-photon absorption coefficients in the near-infrared region are important for nonlinear optics (NLO) applications. In this work, CuLaSe2 and ZnCuLaSe2 QD are successfully synthesized and characterized using UV-Vis, Photoluminescence and HRTEM analysis. Next, the third-order NLO properties of these materials are studied using the femtosecond Z-scan method. The samples showed efficient nonlinear responses. The nonlinear absorption coefficient (& beta;), the nonlinear refractive index (n2) and the third-order nonlinear susceptibility (& chi;(3)) values for all samples are deduced and discussed in detail. The results reported here pave the way towards building CuLaSe2 and ZnCuLaSe2 QDs-based nonlinear photoelectric devices operating in the near-infrared field.
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    Third order nonlinear optical properties of CdTe/CdSe Quasi Type-II Colloidal Quantum Dots
    (Elsevier, 2021) Gundogdu, Yasemin; Kilic, Hamdi Sukur; Cadirci, Musa
    Core/shell Colloidal Quantum Dots (CQDs) are of interest for nonlinear photonic applications due to their unique properties. In this work, firstly CdTe/CdSe Quasi Type-II Colloidal Quantum Dots with an average core size of 3.54 nm and four different shell thicknesses (1.8 nm, 2.7 nm, 3.2 nm and 3.8 nm) were synthesized and characterized using UV-Vis spectroscopy and Transmission electron microscopy (TEM). Secondly nonlinear optical properties of these structures were determined using Femtosecond Z-scan method at the wavelength of 800 nm. Measured values for two photons absorption coefficients (beta) and nonlinear refractive indices (n2) were found to be on the orders of 10-11 cm/W and 10-16 cm2/W, respectively. In addition, the third order nonlinear optical susceptibility values for these structures were calculated to be on the order of 10-10 esu. Quantum dots with thicker shells exhibited faintly higher nonlinear absorption coefficient and slightly lower third order nonlinear optical susceptibility values compared with that of thinner shells. Furthermore, pump power dependant nonlinear optical properties of core/shell nano-structures were investigated and it is observed that two photons absorption coefficient and the third order nonlinear optical susceptibility are pump dependant, while nonlinear refractive indices does not respond to the pump power.
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    Third-order nonlinear optical properties of CsPbCl3 and CsPbBr3 perovskite quantum dots: Effects of particle size and surface traps
    (Elsevier, 2023) Cadirci, Musa; Gundogdu, Yasemin; Bakay, Melahat Sevgul; Kilic, Hamdi Sukur
    Particle size and surface trap effects on the third-order nonlinear optical (NLO) properties of CsPbCl3 and CsPbBr3 perovskite quantum dots (PQD) have been investigated using a femtosecond (fs) z-scan experiment. Firstly, optical, morphological, and structural characterizations of the synthesized PQDs were performed using linear absorption and photoluminescence (PL) spectra, XRD, and TEM methods. Next, NLO properties of CsPbCl3 and CsPbBr3 PQDs were studied at the operating wavelength of 800 nm and 3.564 x 1011 W/cm2 laser intensity. The nonlinear absorption coefficient (& beta;), the nonlinear refraction coefficient (& gamma;), and the third-order susceptibilities (& chi;(3)) values for both sample types were calculated to be on the order of 10-11 m/W, 10-17 m2/W, and 10-11 esu, respectively. The effects of particle size and surface trap sites on the nonlinear properties of the PQDs were studied thoroughly. & gamma;, & chi; (3), and the unitless nonlinear figure of merits (FOM) parameters were realized to be proportional to the particle size for both types of materials. In addition, these parameters were improved by decreasing the surface trap sites in the PQDs. These results strongly indicate the significant potential of CsPbCl3 and CsPbBr3 PQDs for numerous nonlinear applications.