Linear and nonlinear intersubband optical absorption coefficients and refractive index changes in a quantum box with finite confining potential

Ünlü, Selim; Karabulut, İbrahim; Şafak, Haluk

doi:10.1016/j.physe.2006.03.163

Physica E: Low-dimensional Systems and Nanostructures

2006

DOI: 10.1016/j.physe.2006.03.163

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Linear and nonlinear intersubband optical absorption coefficients and refractive index changes in a quantum box with finite confining potential

Selim Ünlü

İbrahim Karabulut

Haluk Şafak

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Cited by 225 publications

(50 citation statements)

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“…In particular, the enhancement of nonlinear optical properties is important in QDs. Nonlinear properties depend on incident optical intensity; thus, at high incident intensities, the nonlinear properties should be considered.Researchers have recently investigated the electronic structure and the linear and nonlinear optical properties of different shapes of QDs, such as the box-shaped [1] , parabolic cylinder [3] , lens-shaped [4] , spherical [5] , and disc-like [6] QDs with finite, infinite, or Gaussian confining potential.Self-assembled InAs/GaAs QDs formed through Stranski-Krastanow growth can be pyramid-shaped [2] . These systems are important for laser applications [7] .…”

mentioning

confidence: 99%

“…Researchers have recently investigated the electronic structure and the linear and nonlinear optical properties of different shapes of QDs, such as the box-shaped [1] , parabolic cylinder [3] , lens-shaped [4] , spherical [5] , and disc-like [6] QDs with finite, infinite, or Gaussian confining potential.…”

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confidence: 99%

“…These quantum systems, which were first studied by Esaki in 1970 [1] , are described as "artificial atoms" because of their δ-function-like density of states [2] . Unlike bulk crystals with band energies, QDs have discrete subbands because of their three-dimensional (3D) confinements.…”

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confidence: 99%

“…Using the compact density matrix formulation of quantum mechanics, the linear and third-order nonlinear AC(RI) are obtained by [1] …”

mentioning

confidence: 99%

“…The following parameters are used in the calculations: ε = 13.18, σ ν = 3 × 10 16 cm −3 , n r = 3.2, and Γ 12 = 5ps −1 [1] . Figures 3(a) and (b) represent the linear, third-order nonlinear, and total AC and RI changes of a CQD as a function of photon energy ω for I = 0.4 MW/cm 2 , a basis radius of R ′ =10 nm, and an apex angle of α = π 4 [2] .…”

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confidence: 99%

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Exact investigation of the electronic structure and the linear and nonlinear optical properties of conical quantum dots

Dezhkam

Zakery

2012

Chin. Opt. Lett.

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Intersubband linear and third-order nonlinear optical properties of conical quantum dots with infinite barrier potential are studied. The electronic structure of conical quantum dots through effective mass approximation is determined analytically. Linear, nonlinear, and total absorption coefficients, as well as the refractive indices of GaAs conical dots, are calculated. The effects of the size of the dots and of the incident electromagnetic field are investigated. Results show that the total absorption coefficient and the refractive index of the dots largely depend on the size of the dots and on the intensity and polarization of the incident electromagnetic field.OCIS codes: 190.4720, 160.4760. doi: 10.3788/COL201210.121901.Quantum dots (QDs) are quasi-zero-dimension systems, the carriers of which are confined in all the three spatial dimensions. These quantum systems, which were first studied by Esaki in 1970 [1] , are described as "artificial atoms" because of their δ-function-like density of states [2] . Unlike bulk crystals with band energies, QDs have discrete subbands because of their three-dimensional (3D) confinements. Intersubband transitions result in physical and optical properties and make QDs useful for infrared (IR) optoelectronic devices. The absorption coefficient (AC) and refractive index (RI) of the host material change because of the considerably large dipole matrix element and the low energy of intersubband transitions. In particular, the enhancement of nonlinear optical properties is important in QDs. Nonlinear properties depend on incident optical intensity; thus, at high incident intensities, the nonlinear properties should be considered.Researchers have recently investigated the electronic structure and the linear and nonlinear optical properties of different shapes of QDs, such as the box-shaped [1] , parabolic cylinder [3] , lens-shaped [4] , spherical [5] , and disc-like [6] QDs with finite, infinite, or Gaussian confining potential.Self-assembled InAs/GaAs QDs formed through Stranski-Krastanow growth can be pyramid-shaped [2] . These systems are important for laser applications [7] . Thus, researchers have approximated the pyramids by using cones to obtain the energy levels of conical quantum dots (CQDs) [8−10] . In this letter, a CQD with an infinite barrier potential is considered. The Schrödinger equation in the effective mass approximation is solved analytically to determine the electronic structure of CQDs. Subsequently, the linear, third-order nonlinear, and total AC and RI changes are investigated. Moreover, the dependencies of these optical properties on QD size and on the intensity and polarization of the incident electromagnetic field are studied.We consider that an electron confined in a CQD has an infinite barrier potential, i.e., V (r) = 0 inside and V (r) = ∞ outside the CQD. To solve this problem analytically, we consider several assumptions, i.e., we deem the potential outside of the QD to be infinite, although in reality, the wavefunctions penetrate into the host ma...

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confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

“…Using the compact density matrix formulation of quantum mechanics, the linear and third-order nonlinear AC(RI) are obtained by [1] …”

mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Exact investigation of the electronic structure and the linear and nonlinear optical properties of conical quantum dots

Dezhkam

Zakery

2012

Chin. Opt. Lett.

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Third-order nonlinear absorption spectra of an impurity in a spherical quantum dot with different confining potential

Yılmaz

Şahin

2009

phys. stat. sol. (b)

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In this study, the linear and third-order nonlinear optical absorption coefficients of intersublevel transitions have been calculated for a spherical CdS/SiO 2 quantum dot (QD) with infinite and different finite confining potential by using the density matrix formalism. The electron eigenenergies and the corresponding wavefunctions have been determined by the variational method under the effective mass approximation. We have investigated the effects of the incident optical intensity, QD radius, and confinement potential on the intersublevel optical absorption coefficients. It is found that the size of the dot and depth of the confinement have a great effect on the linear, the nonlinear, and the total absorption coefficients. Also, the total optical absorption saturation intensity is controlled by the strength of the confinement or the incident optical intensity.

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Intersubband optical absorption coefficients and refractive index changes in a V‐groove quantum wire

Khordad

Khaneghah

2011

Physica Status Solidi (b)

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In this paper, the intersubband optical absorption coefficients and the refractive index changes are studied in a V-groove quantum wire. We use analytical expressions for these properties obtained by the compact-density matrix formalism. In this regard, the linear, nonlinear and total intersubband absorption coefficients and refractive index changes are investigated as a function of the bend width wire (b), the incident optical intensity (I), and the angle u. According to the results obtained from the present work, it is deduced that: (i) The linear terms in the refractive index changes and absorption coefficients dose not change with incident optical intensity whereas nonlinear terms depend on incident optical intensity; (ii) The total refractive index changes and the absorption coefficients reduce as the incident optical intensity increases; (iii) The total absorption coefficient and refractive index changes increase and also shift toward higher energies as the bend width wire increases; and (iv) The total refractive index changes and absorption coefficients shift toward higher energies as the angle u increases.

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Linear and nonlinear intersubband optical absorption coefficients and refractive index changes in a quantum box with finite confining potential

Cited by 225 publications

References 23 publications

Exact investigation of the electronic structure and the linear and nonlinear optical properties of conical quantum dots

Exact investigation of the electronic structure and the linear and nonlinear optical properties of conical quantum dots

Third-order nonlinear absorption spectra of an impurity in a spherical quantum dot with different confining potential

Intersubband optical absorption coefficients and refractive index changes in a V‐groove quantum wire

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