Yazar "Sayraç, Muhammed" seçeneğine göre listele

Listeleniyor 1 - 7 / 7
  • Küçük Resim Yok
    Öğe
    Generation of Coherent XUV Radiation in Gas Mixture of N2 and H2 using High Power Laser System
    (2021) Sayraç, Muhammed
    High harmonic generation is studied in gas species, namely pure H2, pure N2, and their mixture in 1:1 ratio. Observation of harmonic orders from 17H to 35H orders is well resolved. The harmonic spectrum produced from pure H2 is obtained, and the harmonic signal is weaker compared to that produced from pure N2 and their mixture. On the other hand, harmonic yield in the gas mixture is enhanced compared to that from pure H2. The maximum photon energy that harmonic orders can reach is calculated with the well-known cutoff formula. The experiment and the calculation results are in close agreement. In the mixture of N2:H2, the higher harmonics are enhanced compared to the plateau region harmonics. The enhancement of 35H orders in pure N2 or H2-N2 mixture is observed compared to pure H2.
  • Küçük Resim Yok
    Öğe
    High Harmonic Generation Produced in Molecular Nitrogen using Ultrashort Optical Pulses
    (2022) Sayraç, Muhammed
    Generation of coherent extreme ultraviolet (XUV) pulses is a nonlinear process of high harmonic generation (HHG). HHG produced in molecular nitrogen (N2) medium has been obtained using ultrashort intense laser pulses. The strong laser field was focused onto a gas cell to produce short wavelengths having photon energy up to 54 eV. The highest photon energy is experimentally observed as the 35th order. The absorption of harmonics restricts the harmonic yield efficiency. The harmonic yield is affected by the interaction length and medium pressure. The harmonic yield changes with the medium parameters. The simulation for the absorption length was performed using the Mathematica program. Variation of the harmonic signal has been attributed to the absorption of harmonics, and it is compared with the absorption length.
  • Küçük Resim
    Öğe
    Interband transitions and exciton binding energy in a Razavy quantum well: effects of external fields and Razavy potential parameters
    (2022) Sayraç, Muhammed; John Peter, A.; Ungan, Fatih
    In this paper, we theoretically investigated the influence of externally applied fields such as high-frequency non-resonant intense laser fields, static electric and magnetic fields, as well as structure parameters, on the interband transitions and exciton binding energy of a GaAs quantum well with Razavy confinement potential. To perform numerical calculations, the ground state electron and heavy hole subband energy levels of the structure and the envelope wave functions corresponding to these states were calculated using a variational method within the framework of the effective mass and parabolic band approaches. After obtaining the numerical values, the band transitions of the structure, the exciton binding energy, the dipole moment matrix elements, and the transition energy between the ground state electron and heavy hole subband energies of the structure were evaluated in detail. The results show that the Razavy potential profile turns into a single QWstructure for particular dimensionless structure parameters and the peak position of the interband transition coefficient shifts toward red (lower energy) with the increase in the structure parameters and electric field strength, while it shifts toward the blue (higher energy) with the increase in the intensity of the intense laser field and magnetic field.We believe that these numerical results will be useful in the design and production of next-generation electronic and optoelectronic devices.
  • Küçük Resim
    Öğe
    The nonlinear optical rectification, second and third harmonic generation coefficients of Konwent potential quantum wells
    (2022) Sayraç, Muhammed; Martinez-Orozco, Juan Carlos; Mora-Ramos, Miguel Eduardo; Ungan, Fatih
    We have theoretically investigated the effect of structure parameters and applied external fields on the Ga1−xAlxAs/GaAs Konwent quantum well structure. Results of theoretical simulation have clarified the impact of applied external electric and magnetic fields, non-resonant intense laser field, as well as of the change in structure parameters, on the nonlinear optical rectification (NOR), second harmonic generation (SHG), and third harmonic generation (THG) in quantum wells with the Konwent potential. To evaluate these coefficients, we have solved the Schrödinger wave equation using the diagonalization method within the framework of the effective mass and single parabolic band approximations.Wave functions and the subband energy levels for the lowest bounded four states confined within the structure have been obtained. Then, NOR, SHG, and THG coefficient expression have been evaluated as functions of the incident photon energy. It is concluded that the appropriate choice of structure parameters and applied external fields could control the nonlinear optical properties of the Konwent potential quantum wells. The energy levels and the corresponding wavefunctions change with the applied external fields. The energy level change results in the shift of the peak position while the wavefunction change causes the variation in the dipole moment matrix elements, which affect the amplitude of the resonant peaks.
  • Küçük Resim Yok
    Öğe
    Numerical Investigation of Diffraction Patterns of Small Size Apertures Using Light Sources From Xuv to The Visible Region: Simulation for The Small Size Structures
    (2023) Sayraç, Muhammed; Kaynar, Emine; Ungan, Fatih
    In the present work, a computer simulation program generates Fresnel diffraction patterns from small-size apertures using illumination wavelengths from extreme ultraviolet (XUV) to the visible region suggesting that it can be used to model a wide range of experimental setups. By being able to simulate diffraction patterns for such a broad range of wavelengths, the program can be used to investigate the effects of varying wavelengths and aperture size on the resulting pattern. By using a computer simulation program that can generate Fresnel diffraction patterns across a wide range of wavelengths, one can explore how different wavelengths of light interact with various aperture sizes. This allows one to investigate the effects of changing these parameters on the resulting diffraction pattern. The computer simulation program generating Fresnel diffraction patterns from square apertures by using the illumination wavelength sources from XUV to the visible region has been studied. Changing the aperture-screen distance, the illumination wavelength, and the aperture size provides a clear transition of diffraction patterns from the Fresnel to the Fraunhofer region. The diffraction patterns obtained by the Fresnel integral method have been compared with that simulated by the Fraunhofer calculation. There is a good agreement between the results. The structural similarity index (SSI) exhibits that comparing the diffraction images produced with both approaches agree.
  • Küçük Resim Yok
    Öğe
    Numerical Simulation of Coherent Extreme Ultraviolet Radiation by Considering Simple Hydrogen Atomic Potential
    (2023) Sayraç, Muhammed
    In this study, the ionization of a single electron exposed to an intense laser field is computed, and the nonlinear dipole response of a single electron is obtained. The ionization of a single electron exposed to an intense laser field can be computed using the strong field approximation (SFA), also known as the Keldysh theory. This method is based on the idea that the laser field is so strong that it can ionize the electron by tunneling through the Coulomb barrier. In this paper, the Xe, Ne, and H2 gas species are modeled since they have simple atomic systems. All gas species have relative or close ionization potentials. Ultra-short pulse duration (50 fs) is accepted because of the shorter time scale than the electron energy-lattice transfer. The ionization potentials of gas species result in the Keldysh parameter being smaller than one. The electron dipole oscillation spectra of these gas species are simulated by calculating the dipole spectrum considering the Lewenstein model. The electron propagation under the different wavelengths is simulated. The effects of the different driving wavelengths have noticeable effects on the enhancement and the extension of the extreme ultraviolet radiation signal.
  • Küçük Resim Yok
    Öğe
    Sputtered AlN for Distributed Bragg Reflectors Operating in the SWIR Wavelengths
    (Optica Publishing Group (formerly OSA), 2022) Kaynar, Emine; Hopoglu, Hicret; Altuntas, Ismail; Demir, Ilkay; Sayraç, Muhammed; Tüzemen, Ebru S.; Alaydin, B. Özgür
    In this study, we aim to eliminate low thermal conductivity and refractive index differences in InP and GaSb based materials, which result in low output power and limited operation wavelength range for VECSELs. © 2022 OSA - The Optical Society. All rights reserved.