Physics / Fizik

Permanent URI for this collectionhttps://hdl.handle.net/11147/6

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Author: search.filters.author.Çetin, Zebih

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  • Article
    Citation - WoS: 4
    Citation - Scopus: 4
    Photonic Crystal Textiles for Heat Insulation
    (American Institute of Physics, 2023) Çetin, Zebih; Tunçtürk, Yiğit; Sözüer, Hüseyin Sami
    In this work, we have studied transmission properties of a photonic crystal-like structure that can be woven into fabrics. An interesting possibility emerges when considering the potential energy savings through suppression of radiation. It is a well-established fact that every object at a finite temperature inherently emits electromagnetic waves. Within the specific context of the human body, radiation takes on a crucial role as a fundamental mechanism governing heat dissipation. Thus, exploring ways to manage or mitigate this radiation could offer innovative approaches to optimize energy consumption and enhance heat regulation. It is well known that a photonic crystal can block electromagnetic energy with a specific frequency that is falling into a photonic bandgap. By using the numerical method called a finite-difference time domain, we have shown that this property of a periodic structure can be used to make textiles to save energy that is used to heat a human body environment. Numerical calculations have shown that by using the proposed photonic crystal structure, 53 % of electromagnetic energy is reflected. Although we mainly focused on textiles, it is worth highlighting that the same fundamental principle can be extended to diverse fields; for example, this structure can be integrated with construction materials and effectively function as a radiation heat insulator. © 2023 Author(s).
  • Article
    Citation - WoS: 2
    Citation - Scopus: 2
    Analytical Improvement on the Electromagnetic Scattering From Deformed Spherical Conducting Objects
    (Institute of Electrical and Electronics Engineers, 2021) Ateş, Barış; Kuştepeli, Alp; Çetin, Zebih
    In this paper, electromagnetic scattering from con-ducting deformed spheres is considered analytically by employing the perturbation method and utilizing Debye potentials. To be able to analyze a wide variety of scattering problems, azimuthal variation is indispensable and therefore the geometries of the scatterers considered in this study do not have rotational symmetry, hence they are dependent on the θ and φ angles in spherical coordinates. Analyses are carried up to the second order explicitly to obtain more accurate results and thus scattered fields are obtained with second order corrections. The coefficients used to determine the scattered field are expressed in terms of Clebsch-Gordan coefficients, which enables one to obtain the results for new geometries only by simple algebraic manipulations. Numerical results and their comparisons are also presented for various deformation functions and parameters. IEEE
  • Article
    Citation - WoS: 1
    Citation - Scopus: 1
    Fully Three-Dimensional Analysis of a Photonic Crystal Assisted Silicon on Insulator Waveguide Bend
    (World Scientific Publishing, 2018) Eti, Neslihan; Çetin, Zebih; Sözüer, Hüseyin Sami
    A detailed numerical study of low-loss silicon on insulator (SOI) waveguide bend is presented using the fully three-dimensional (3D) finite-difference time-domain (FDTD) method. The geometrical parameters are optimized to minimize the bending loss over a range of frequencies. Transmission results for the conventional single bend and photonic crystal assisted SOI waveguide bend are compared. Calculations are performed for the transmission values of TE-like modes where the electric field is strongly transverse to the direction of propagation. The best obtained transmission is over 95% for TE-like modes.