Quadratic optical effects in ZnS/CdS/ZnS quantum dot-quantum well (original) (raw)
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Standards, Methods and Solutions of Metrology, 2019
Quantum dots (QDs) are semiconducting nanocrystalline particles. QDs are attractive photonic media. In this chapter, we introduce third-order nonlinear optical properties and a brief idea about the physics of QDs. Z-scan technique and theoretical analysis adopted to obtain nonlinear parameters will be discussed. Analysis of third-order nonlinear optical parameters for PbS QDs suspended in toluene with radii 2.4 and 5.0 nm under different excitation beam power level and three different wavelengths (488, 514, and 633 nm) will be detailed. Third-order optical susceptibility χ (3) and optical-limiting behavior of PbS QD suspended in toluene are presented. Irrespective of their size, QDs are a good example of optical limiters with low threshold.
Nanomaterials
A theoretical analysis of optical properties in a ZnS/CdS/ZnS core/shell/shell spherical quantum dot was carried out within the effective mass approximation. The corresponding Schrödinger equation was solved using the finite element method via the 2D axis-symmetric module of COMSOL-Multiphysics software. Calculations included variations of internal dot radius, the application of electric and magnetic fields (both oriented along z-direction), as well as the presence of on-center donor impurity. Reported optical properties are the absorption and relative refractive index change coefficients. These quantities are related to transitions between the ground and first excited states, with linearly polarized incident radiation along the z-axis. It is found that transition energy decreases with the growth of internal radius, thus causing the red-shift of resonant peaks. The same happens when the external magnetic field increases. When the strength of applied electric field is increased, the ...
Nanoengineering the second order susceptibility in semiconductor quantum dot heterostructures
Optics Express, 2011
We study second-harmonic generation from single CdTe/CdS core/shell rod-on-dot nanocrystals with different geometrical parameters, which allow to fine tune the nonlinear properties of the nanostructure. These hybrid semiconductor-semiconductor nanoparticles exhibit extremely strong and stable second-harmonic emission, although the size of CdTe core is still within the strong quantum confinement regime. The orientation sensitive polarization response is analyzed by means of a pointwise additive model of the third-order tensors associated to the nanoparticle components. These findings prove that engineering of semiconducting complex heterostructures at the single nanoparticle scale can lead to extremely bright nanometric nonlinear light sources. "X-ray diffraction study of CdS/CdTe heterostructure for thin-film solar cell: influence of CdS grain size on subsequent growth of (111)-oriented CdTe film," J. Phys. D: Appl. Phys. 39, 1537-1542 (2006). 31. S. Brasselet and J. Zyss, "Multipolar molecules and multipolar fields: probing and controlling the tensorial nature of nonlinear molecular media," J. Opt. Soc. Am. B 15, 257-288 (1998). 32. J. Zyss, "Molecular engineering implications of rotational invariance in quadratic nonlinear optics: From dipolar to octupolar molecules and materials," J.
Chemical Physics Letters, 2020
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Optik, 2021
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Study of nonlinear optical susceptibility of defective shell spherical quantum dot
Optik - International Journal for Light and Electron Optics, 2017
In this paper, the nonlinear third order susceptibility of proposed new GaN/AlGaN defective shell spherical quantum dot is calculated by using the effective mass approximation. The new proposed nanostructure is containing defective shell surrounding with two spherical well. The size of quantum dot, defective shell thickness, defect position and potentials of defect region have a significant effect on third order optical susceptibility. The results are shown that with increasing of quantum dot size the third order susceptibility is increased and resonance wavelength is red shifted due to quantum confinement effect. Also, with increasing of defective shell thickness nonlinear susceptibility is increased. The increasing of third order susceptibility and red shifting of resonance wavelength are occurring with increasing of defect potential too. The largest value of third order susceptibility is achieved when in the symmetric condition of defect position, the defect potential becomes equal to barrier potential.
Journal of Nanoparticle Research, 2011
In this article, we have investigated the photoluminescence intensity of quantum dot-quantum well heteronanocrystal with non-linear potential profile which has been analyzed by the finite element numerical methods and is compared with traditional potential profile of same heteronanocrystal. We have probed the effect of carrier localization in layers of heteronanocrystal on the photoluminescence intensity. Moreover, the effects of variation of radius layers such as CdSe core, shell, and ZnS barriers radius on the photoluminescence intensity are studied. Besides, for the first time, we demonstrated the shift of quantum dot-quantum well operation wavelength by introducing non-linear potential profile in the core of heteronanocrystal that can be drastically affected on biological application. Furthermore, in biological application, by tuning the emission wavelengths of quantum dot into the far-red and nearinfrared ranges, the non-invasive in vivo imaging technique was developed. In this wavelength window, tissue absorption, scattering, and auto-fluorescence intensities have minimum quantities. In our article with new structure, the relation between size and operation wavelength don't follow traditional relation.
Mathematical modelling of optical properties of CdSe/ZnS core shell quantum dot
In this paper, the electron and hole energies are computed for core/shell quantum dots (CSQDs) using two ways. First, we have resolved the three dimensional Schrödinger equation in the spherical coordinate system. The second approach is based on a combination of coordinate transformation and the finite difference method. The carrier energy levels of CdSe/ZnS CSQD are investigated, then the transition energies and the oscillator strength are deduced.
Journal of Applied Physics
To increase the optical nonlinearity effects in hybrid structures comprising a quantum dot and a nanoparticle, a quantum dot is taken as a three-level system. Under the dipole–dipole interactions between the quantum dot and the nanoparticle, the density matrix elements are derived within the rotating approximation. Under the quasi-static approximation by taking the nanoparticle polarization as a function of its geometry, the induced fields around the quantum dot in the presence of one/two nanoparticle(s) are obtained and the increasing factors of the local fields are calculated. The third-order nonlinear optical susceptibility of quantum dot is achieved by using the perturbation expansion theory of density matrix for different geometries of the nanoparticle, and the effects of the structural parameters are investigated to optimize the nonlinear optical response of the system. It can be seen that the presence of two nanorods results in great optical nonlinearities in the hybrid struc...