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Excitonic effects on the second-order nonlinear optical properties of semi-spherical quantum dots.

Flórez J, Camacho A - Nanoscale Res Lett (2011)

Bottom Line: The exciton is confined in a semi-spherical geometry by means of a three-dimensional semi-parabolic potential.We calculate the optical rectification and second harmonic generation coefficients for two different values of the confinement frequency based on the numerically computed energies and wavefunctions of the exciton.We find that the second-order nonlinear coefficients exhibit not only a blue-shift of the order of meV but also a change of intensity compared with the results obtained ignoring the Coulomb interaction in the so-called strong-confinement limit.

View Article: PubMed Central - HTML - PubMed

Affiliation: Departamento de Física, Universidad de los Andes, A,A, 4976, Bogotá, DC, Colombia. j.florez34@uniandes.edu.co.

ABSTRACT
We study the excitonic effects on the second-order nonlinear optical properties of semi-spherical quantum dots considering, on the same footing, the confinement potential of the electron-hole pair and the Coulomb interaction between them. The exciton is confined in a semi-spherical geometry by means of a three-dimensional semi-parabolic potential. We calculate the optical rectification and second harmonic generation coefficients for two different values of the confinement frequency based on the numerically computed energies and wavefunctions of the exciton. We present the results as a function of the incident photon energy for GaAs/AlGaAs quantum dots ranging from few nanometers to tens of nanometers. We find that the second-order nonlinear coefficients exhibit not only a blue-shift of the order of meV but also a change of intensity compared with the results obtained ignoring the Coulomb interaction in the so-called strong-confinement limit.

No MeSH data available.


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The SHG coefficient as a functions of the incident photon energy ħω for (a) ω0 = 1 × 1013 s-1 and (b) ω0 = 2 × 1014 s-1, considering excitonic effects with (red line) and without Coulomb (black line)interaction. The blue line corresponds to the case without excitonic effects.
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Figure 3: The SHG coefficient as a functions of the incident photon energy ħω for (a) ω0 = 1 × 1013 s-1 and (b) ω0 = 2 × 1014 s-1, considering excitonic effects with (red line) and without Coulomb (black line)interaction. The blue line corresponds to the case without excitonic effects.

Mentions: The terms involving quantum states and energies in Equations 13 and 19 are found using the eigenstates and eigenenergies previously calculated. The OR and SHG coefficients are shown in Figures 2 and 3, respectively. Figures 2a and 3a correspond to ω0 = 1 × 1013 s-1, and Figures 2b and 3b to ω0 = 2 × 1014 s-1. In each figure, we present the corresponding nonlinear optical coefficient considering excitonic effects with and without Coulomb interaction. For comparative purposes, we also present the case without excitonic effects, i.e., when only one electron exists in the quantum dot.


Excitonic effects on the second-order nonlinear optical properties of semi-spherical quantum dots.

Flórez J, Camacho A - Nanoscale Res Lett (2011)

The SHG coefficient as a functions of the incident photon energy ħω for (a) ω0 = 1 × 1013 s-1 and (b) ω0 = 2 × 1014 s-1, considering excitonic effects with (red line) and without Coulomb (black line)interaction. The blue line corresponds to the case without excitonic effects.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211331&req=5

Figure 3: The SHG coefficient as a functions of the incident photon energy ħω for (a) ω0 = 1 × 1013 s-1 and (b) ω0 = 2 × 1014 s-1, considering excitonic effects with (red line) and without Coulomb (black line)interaction. The blue line corresponds to the case without excitonic effects.
Mentions: The terms involving quantum states and energies in Equations 13 and 19 are found using the eigenstates and eigenenergies previously calculated. The OR and SHG coefficients are shown in Figures 2 and 3, respectively. Figures 2a and 3a correspond to ω0 = 1 × 1013 s-1, and Figures 2b and 3b to ω0 = 2 × 1014 s-1. In each figure, we present the corresponding nonlinear optical coefficient considering excitonic effects with and without Coulomb interaction. For comparative purposes, we also present the case without excitonic effects, i.e., when only one electron exists in the quantum dot.

Bottom Line: The exciton is confined in a semi-spherical geometry by means of a three-dimensional semi-parabolic potential.We calculate the optical rectification and second harmonic generation coefficients for two different values of the confinement frequency based on the numerically computed energies and wavefunctions of the exciton.We find that the second-order nonlinear coefficients exhibit not only a blue-shift of the order of meV but also a change of intensity compared with the results obtained ignoring the Coulomb interaction in the so-called strong-confinement limit.

View Article: PubMed Central - HTML - PubMed

Affiliation: Departamento de Física, Universidad de los Andes, A,A, 4976, Bogotá, DC, Colombia. j.florez34@uniandes.edu.co.

ABSTRACT
We study the excitonic effects on the second-order nonlinear optical properties of semi-spherical quantum dots considering, on the same footing, the confinement potential of the electron-hole pair and the Coulomb interaction between them. The exciton is confined in a semi-spherical geometry by means of a three-dimensional semi-parabolic potential. We calculate the optical rectification and second harmonic generation coefficients for two different values of the confinement frequency based on the numerically computed energies and wavefunctions of the exciton. We present the results as a function of the incident photon energy for GaAs/AlGaAs quantum dots ranging from few nanometers to tens of nanometers. We find that the second-order nonlinear coefficients exhibit not only a blue-shift of the order of meV but also a change of intensity compared with the results obtained ignoring the Coulomb interaction in the so-called strong-confinement limit.

No MeSH data available.


Related in: MedlinePlus