Yazar "Sokmen, Ismail" seçeneğine göre listele

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    Effect of Intense Laser Field in Gaussian Quantum Well With Position-Dependent Effective Mass
    (Wiley-V C H Verlag Gmbh, 2019) Sari, Huseyin; Kasapoglu, Esin; Sakiroglu, Serpil; Sokmen, Ismail; Duque, Carlos A.
    In this paper, the effects of the intense laser field (ILF) and position dependent mass (PDM) on the electronic structure in a Gaussian quantum well are theoretically deduced by using the diagonalization method for obtaining energy levels and corresponding wave functions. We find that, in the case of narrow PDM distribution, the dependence of the energy levels on the effective length of the electron mass distribution becomes more apparent, and the evolution of the dressed mass with ILF is significant. Given this feature, it is more meaningful to take into consideration the PDM of the electron in the low dimensional semiconductor heterostructures under the ILF.
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    The effect of magnetic field on the impurity binding energy of shallow donor impurities in a Ga1-xInxNyAs1-y/GaAs quantum well
    (SPRINGER, 2012) Yesilgul, Unal; Ungan, Fatih; Sakiroglu, Serpil; Duque, Carlos; Mora-Ramos, Miguel; Kasapoglu, Esin; Sari, Huseyin; Sokmen, Ismail
    Using a variational approach, we have investigated the effects of the magnetic field, the impurity position, and the nitrogen and indium concentrations on impurity binding energy in a Ga1-x In (x) N (y) As1-y /GaAs quantum well. Our calculations have revealed the dependence of impurity binding on the applied magnetic field, the impurity position, and the nitrogen and indium concentrations.
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    Effect of the High-Frequency Laser Radiation on the Nonlinear Optical Properties of n-Type Double delta-Doped GaAs Quantum Wells
    (AMER SCIENTIFIC PUBLISHERS, 2019) Ungan, Fatih; Sari, Huseyin; Kasapoglu, Esin; Yesilgul, Unal; Sakiroglu, Serpil; Sokmen, Ismail
    In the present work, the effect of non-resonant intense laser field on the nonlinear optical rectification and second and third harmonic generation of n-type double delta-doped GaAs quantum well is studied in detail. The energy eigenvalues and eigenfunctions of this structure are calculated within the framework of effective mass and envelope function approximations. Analytic formulas for the coefficients of nonlinear optical rectification and second and third harmonic generation are obtained using the compact-density matrix approach (CDMA) and iterative method. Based on this model, our obtained numerical results are reported as a function of incident photon energy for several values of non-resonant intense laser field. The results show that the coefficients of nonlinear optical rectification and second and third harmonic generation are strongly affected by the non-resonant intense laser field.
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    Effect of the intense laser field on the valance band for Ga1-xAlxAs/GaAs heterostructure
    (ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 2009) Ozturk, Emine; Sokmen, Ismail
    The energy levels of holes in symmetric single quantum well under the laser field are theoretically calculated within the framework of the effective mass approximation. Results obtained show that the potential profile and energy levels can significantly be modified and controlled by intense laser field and the well width. The effect of the laser field and the well width on the energy difference changes the degree of the confinement, and thus this behavior can be used to study these systems in regions of interest, without the need for the growth of many different samples. (C) 2008 Elsevier Ltd. All rights reserved.
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    Effects of an intense, high-frequency laser field on bound states in Ga1-xInxNyAs1-y/GaAs double quantum well
    (SPRINGER, 2012) Ungan, Fatih; Yesilgul, Unal; Sakiroglu, Serpil; Kasapoglu, Esin; Erol, Ayse; Arikan, Mehmet Cetin; Sari, Huseyin; Sokmen, Ismail
    Within the envelope function approach and the effective-mass approximation, we have investigated theoretically the effect of an intense, high-frequency laser field on the bound states in a Ga (x) In1 - x N (y) As1 - y /GaAs double quantum well for different nitrogen and indium mole concentrations. The laser-dressed potential, bound states, and squared wave functions related to these bound states in Ga1 - x In (x) N (y) As1 - y /GaAs double quantum well are investigated as a function of the position and laser-dressing parameter. Our numerical results show that both intense laser field and nitrogen (indium) incorporation into the GaInNAs have strong influences on carrier localization.
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    The effects of hydrostatic pressure on the nonlinear intersubband transitions and refractive index changes of different QW shapes
    (ELSEVIER SCIENCE BV, 2012) Ozturk, Emine; Sokmen, Ismail
    In this study, the effects of hydrostatic pressure on the linear and nonlinear intersubband transitions and the refractive index changes in the conduction band of different quantum well shapes are theoretically calculated within framework of the effective mass approximation. Results obtained show that intersubband properties and the energy levels in different QWs can be modified and controlled by the hydrostatic pressure. The modulation of the absorption coefficients and the refractive index changes which can be suitable for good performance optical modulators and various infrared optical device applications can be easily obtained by tuning the hydrostatic pressure strength. (C) 2012 Elsevier B.V. All rights reserved.
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    Intersubband transitions and refractive index changes in coupled double quantum well with different well shapes
    (ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 2011) Ozturk, Emine; Sokmen, Ismail
    In this study, both the linear intersubband transitions and the refractive index changes in coupled double quantum well (DQW) with different well shapes for different electric fields are theoretically calculated within framework of the effective mass approximation. Results obtained show that intersubband transitions and the energy levels in coupled DQW can importantly be modified and controlled by the electric field strength and direction. By considering the variation of the energy differences, it should point out that by varying electric field we can obtain a blue or red shift in the intersubband optical transitions. The modulation of the absorption coefficients and the refractive index changes which can be suitable for good performance optical modulators and various infrared optical device applications can be easy obtained by tuning applied electric field strength and direction. (C) 2011 Elsevier Ltd. All rights reserved.
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    Intersubband transitions in an asymmetric double quantum well
    (ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD, 2007) Ozturk, Emine; Sokmen, Ismail
    The intersubband optical absorption in an asymmetric double quantum well for different barrier widths and the right well widths are theoretically calculated within the framework of effective mass approximation. The results obtained show that the intersubband transitions and the energy levels in an asymmetric double quantum well can be importantly modified and controlled by the barrier width and the well width. The sensitivity to the barrier and well widths of the absorption coefficient can be used in various optical semiconductor device applications. (c) 2006 Elsevier Ltd. All rights reserved.
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    Nonlinear intersubband absorption and refractive index changes in square and graded quantum well modulated by temperature and Hydrostatic pressure
    (ELSEVIER SCIENCE BV, 2013) Ozturk, Emine; Sokmen, Ismail
    In this study, the effects of hydrostatic pressure and temperature on the linear and nonlinear intersubband transitions and the refractive index changes in the conduction band of square and graded quantum well (QW) are theoretically calculated within the framework of effective mass approximation. Results obtained show that the energy levels in different QWs and intersubband properties can be modified and controlled by the hydrostatic pressure and temperature. The modulation of the absorption coefficients and the refractive index changes which can be suitable for good performance optical modulators and various infrared optical device applications can be easily obtained by tuning the temperature and the hydrostatic pressure. (c) 2012 Elsevier B.V. All rights reserved.
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    Nonlinear intersubband transitions in a parabolic and an inverse parabolic quantum well under applied magnetic field
    (ELSEVIER SCIENCE BV, 2014) Ozturk, Emine; Sokmen, Ismail
    In this study, both the intersubband optical absorption coefficients and the refractive index changes as dependent on the magnetic field are calculated in a parabolic (PQW) and an inverse parabolic quantum well (IPQW) for different Al concentrations at the well center. Our results show that the position and the magnitude of the linear, nonlinear and total absorption coefficients and refractive index changes depend on the magnetic field strength and the Al concentration at the well center. By decreasing the Al concentration at the well center we can obtain a red shift and a blue shift in the intersubband optical transitions for PQWs and IPQWs, respectively. Thus, the absorption coefficients and the refractive index changes which can be suitable for great performance optical modulators and multiple infrared optical device applications can be easily obtained by tuning the applicable magnetic field value and the Al concentration at the well center. (C) 2013 Elsevier B.V. All rights reserved.
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    Nonlinear Intersubband Transitions in Square and Graded Quantum Wells Modulated by Intense Laser Field
    (IOP PUBLISHING LTD, 2014) Ozturk, Emine; Sokmen, Ismail
    The intersubband optical absorption coefficients and the refractive index change depending on the intense laser field (ILF); both are calculated in a square quantum well (SQW) and a graded quantum well (GQW). Our results show that the position and the magnitude of the linear, nonlinear and total absorption coefficients and refractive index changes depend on the laser field parameter and the quantum well (QW) shape. By increasing the ILF value, we can obtain a red shift or a blue shift in the intersubband optical transitions as dependent on the shape of the QW. For the SQW, the intersubband absorption spectrum shows a blue shift up to the critical laser field value. This spectrum shows a red shift for ILF values larger than this certain value. For the GQW, the intersubband absorption spectrum shows a red shift by increasing the ILF. Thus the absorption coefficients and the refractive index changes, which can be suitable for great performance optical modulators and multiple infrared optical device applications, can be easily obtained by tuning the ILF value and the QW shape.
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    Nonlinear optical properties of asymmetric n-type double delta-doped GaAs quantum well under intense laser field? (vol 90, 162, 2017)
    (SPRINGER, 2018) Sari, Huseyin; Kasapoglu, Esin; Yesilgul, Unal; Sakiroglu, Serpil; Ungan, Fatih; Sokmen, Ismail
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    Resonant peaks of the linear optical absorption and rectification coefficients in GaAs/GaAlAs quantum well: Combined effects of intense laser, electric and magnetic fields
    (WORLD SCIENTIFIC PUBL CO PTE LTD, 2015) Ozturk, Emine; Sokmen, Ismail
    In this study, the resonant peaks of the linear optical absorption (OA) and rectification coefficients in GaAs/GaAlAs quantum well are calculated as dependent on the applied electric field (F), the magnetic field (B) and the laser field intensity parameter (alpha(0)). Our results show that the shape of confined potential profile, the energy levels and the dipole moment matrix elements are changed as dependent on the F, B and alpha(0). Also, the resonant peaks of the OA and rectification coefficients depend on the applied external field effects. Therefore, the variation of the resonant peaks of these coefficients which can be appropriate for various optical modulators and infrared optical device applications can be smoothly obtained by the alteration electric, magnetic and intense laser field.
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    The variation of electronic properties with the doping concentration of modulation-doped AlxGa1-xAs-GaAs double quantum wells
    (ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD, 2007) Ungan, Fatih; Ozturk, Emine; Ergun, Yuksel; Sokmen, Ismail
    In this paper we have calculated the sub-band structure and the confinement potential of modulation-doped Ga1-xAlxAs-GaAs double quantum wells as a function of the doping concentration. The electronic properties of this structure were determined by self-consistent solutions of the Schrodinger and Poisson equations. To understand the effects of doping concentration on band bending, sub-band energies, and sub-band populations, the doping concentration on one right side of the structure is decreased while holding it constant on the left side. We found that at low doping concentrations on the right side, the effects of the doping concentration are more pronounced on band bending and sub-band populations. (c) 2006 Elsevier Ltd. All rights reserved.