The nonlinear susceptibilities associated with intersubband transitions in the conduction band are theoretically calculated for CdSe/ZnS spherical core–shell quantum dots. The confined wave functions ...and eigenenergies of electrons in quantum dots have been calculated under the effective-mass approximation by solving a three-dimensional Schrödinger equation. And the third-order susceptibilities for quadratic electro–optic effects as a function of core, shell radii, relaxation time and pump photo energy involving the position of energy levels also have been analyzed.
The third-order nonlinear susceptibilities associated with intersubband transition are theoretically calculated for ZnS/CdSe cylindrical quantum dot quantum well. The eigenenergies of electrons and ...wave functions in QDQW have been calculated under the effective-mass approximation by solving a three-dimensional nonlinear Schrödinger equation, and by means of compact density matrix method, the third-order nonlinear susceptibilities for third harmonic generation and quadratic electro-optic effects have been calculated for different sizes of QDQW. By increasing the width of shell well, the peaks of
χ
THG
(
3
)
and
χ
QEOE
(
3
)
as functions of pump photon energy
ℏ
ω
will shift to the lower energy, and the intensities of the peaks will increase.
The resonant third-order susceptibilities at various directions (both parallel and vertical to Z-axis) in self-assembled quantum dots (QDs) have been investigated. The nonlinear susceptibilities ...associated with the intraband transition in the conduction band are theoretically calculated for wurtzite InxGa1−xN/GaN-strained cylinder QDs. The confined wave functions and energies of electrons in the dots have been calculated in the effective-mass approximation by solving the 3D Schrödinger equation, in which a strong built-in electric field effect due to the piezoelectricity and spontaneous polarization has been taken into account. Furthermore, it is shown that the magnitude and the resonant position of the nonlinear susceptibility χ(3)(3ω) strongly depend on the dots’ size as well as size distribution.
The third-order nonlinear optical susceptibility for the third-harmonic generation of a spherical CdTe quantum dot is calculated using effective mass approximation and the density matrix method. The ...variation of susceptibility for the quantum dot induced by a metal nanoparticle is calculated by considering the local field enhancement and the dipole interaction. It is found that the contribution of the local field effect is the significant one, which can lead to considerable enhancement of optical nonlinearity for the quantum dot.
The second-order susceptibilities of GaN/AlGaN QWs have been studied by taking the strain-induced piezoelectric and spontaneous polarization effects into account, and the second-order ...susceptibilities as a function of Al content
x, well width
w, and pump photo energy
hω, have also been analyzed.
Including the contribution of spin–orbit splitting, the wave functions and energy structures of GaN/In
x
Ga
1−
x
N multiple quantum wells (MQWs) have been calculated. For the transition between ...valence band and conduction band, the third-order nonlinear optical susceptibility
χ
(3) of quadratic electro-optic effect (QEOE) for the mode whose polarization is vertical to the 0
0
1 direction of the MQWs, has been calculated. The correlations between
χ
(3) and the width of the MQWs, and the concentration of In, are obtained.
The quadratic electronic-optic effects (QEOE) and electro-absorption process (EA) are calculated and analyzed theoretically for a bundle of semiconductor carbon nanotubes (CNs) with two-band ...approximation. The third-order susceptibility dispersion behaviors of direct current (DC) are obtained and there are several new features, which are important for their potential application as photonic devices. Meanwhile, it is found that for two types of semiconductor carbon nanotubes the nonlinear susceptibilities χ(3) are substantially different and they both strongly depend on nanotubes geometry and considerably increase with the radius of the carbon nanotubes. For instance, χDC(3) of (22, 0) CN is larger than that of (23, 0), but the diameter of the former is smaller than that of the latter. In addition, it is also found that the resonant peak position in the dispersion of χDC(3) is related to the effect of the mixing between π and σ states.
The optical nonlinearities of an InGaN/GaN multiple quantum well (MQW) and a GaN film were experimentally investigated by using femtosecond Z-scan method in this paper. It was observed that the ...InGaN/GaN MQW displays a nonlinear saturable absorption (SA) effect and the nonlinear absorption coefficient
β was determined to be
-
5.5
×
1
0
3
cm
/
GW
; and the GaN film shows a reverse saturable absorption (RSA) effect and the
β is
7.5
×
1
0
3
cm
/
GW
. It is also found that the absorption cross sections and quantum confinement effect (QCE) give an influence on the SA of the InGaN/GaN MQW structure.
