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Linear and nonlinear optical properties of CdSe/ZnTe core/shell spherical quantum dots embedded in different dielectric matrices
摘要： Based on a two-level system, the linear and third-order nonlinear optical properties are analyzed for CdSe/ZnTe spherical core/shell quantum dots embedded in various dielectric matrices including poly-vinyl alcohol, polyethylene and silicon nitride. Our results reveal that by increasing core/shell radii ratio the eigenenergies as well as the transition energy decreased. The presence of the dielectric mismatch in the quantum dot-matrix system can cause significant enhancement of the linear and third-order nonlinear optical susceptibilities. We believe that our findings offer a new degree of freedom in optoelectronic device applications.
关键词： Core/shell,Dielectric matrices,Nonlinear optic,Third-order nonlinear susceptibility
更新于2025-09-23 15:19:57
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Theoretical investigation on the third order nonlinear optical susceptibility in CdS/ZnS/CdS/ZnS core/shell/well/shell quantum dots for optoelectronic applications
摘要： In this paper, a detailed study on the third order nonlinear optical susceptibility for quadratic electro-optic effects for CdS/ZnS/CdS/ZnS core/shell/well/shell spherical quantum dots is realized. Electron energies and corresponding functions are investigated under the frame work of the effective-mass approximation. Then, the third order nonlinear susceptibility is determined using the density matrix method. The dot size effect on this susceptibility is also examined. Numerical calculations confirm that both position and intensity of the peaks can be controlled by varying shell thickness. In addition, by increasing the width of inner or outer shell, the peaks of susceptibility is redshifted and the intensities are increased. Moreover, the 'inverted' structure, ZnS/CdS/ZnS/CdS has shown better nonlinear optical properties.
关键词： third order nonlinear susceptibility,II-VI Semiconductors,Quantum dot quantum well
更新于2025-09-23 15:19:57
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Improvement of the third order nonlinear optical properties of nematic liquid crystal under the influence of different compositional percentage of doped SWCNT and the external electric field
摘要： In this research, the nematic liquid crystal (NLC) was doped with varying concentration (0-1 % wt.) of single walled carbon nanotubes (SWCNTs) at room temperature to study the nonlinear optical (NLO) properties of E5CN7@CNT cell.The third order NLO properties such as the nonlinear susceptibility, the nonlinear refraction (NLR) and the nonlinear absorption (NLA) were determined by using Z-scan techniques. The nonlinear studies have been done using a continuous wave (CW) He: Ne laser at 632.8 nm.Doping SWCNTs to eutectic uniaxial NLC (E5CN7) enhanced the third order nonlinear susceptibility, ??(3) and consequently the nonlinearity properties of composite systems improved.It is found that at lower concentration of CNTs (c< 0.75 % wt.), the third order nonlinear susceptibility are increased, but for concentration 0. 5<c<1 % wt., the third order nonlinear susceptibility are decreased. The negative sign of the observed NLR index, indicates that the E5CN7@CNT exhibits self-defocusing type optical nonlinearity. The two photon absorption (TPA) behavior, corresponding to negative sign NLA of samples. The reorientation of samples molecules amplifies upon the application of electric field, then nonlinearity increases.
关键词： Composite materials,Nematic liquid crystal,Carbon nanotubes,Third order nonlinear susceptibility,Nonlinear optics,Electric field,Z-scan method
更新于2025-09-10 09:29:36