Electrical - Electronic Engineering / Elektrik - Elektronik Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/11

Browse

Filters

Settings

Department: search.filters.department.İzmir Institute of Technology. Electrical and Electronics EngineeringInstitution Author: search.filters.institutionAuthor.Dinleyici, Mehmet Salih

Search Results

Now showing 1 - 10 of 22
  • Article
    Citation - WoS: 1
    Citation - Scopus: 1
    Experimental Demonstration of a Transient Grating Controlled All-Optical Switch
    (IOP Publishing, 2023) Akın, Osman; Dinleyici, Mehmet Salih
    We demonstrate an on-fiber all-optical switching device based on a transient grating formed by the interference of control laser pulses in a Kerr-type nonlinear material placed in the evanescent region of the fiber. The device can operate in two distinctive modes. First, switching/coupling among the fiber modes using bulk index modulation was investigated and an efficiency of about %0.55 @852 nm was measured. Second, by exploiting Four Wave Mixing (FWM), an all-optical switching that transfers power among light signals with wavelengths of λ 1 = 440 nm and λ 2 = 663 nm was achieved by quasi-phase-matching and fRequency matching in a nonlinear thin polymeric film. The results prove that the introduced switching structure may have the potential to be used in integrated photonic applications such as intensity modulators or controllable couplers.
  • Article
    Citation - WoS: 5
    Citation - Scopus: 5
    Nanoscale Curved Dielectric Film Characterization Beyond Diffraction Limits Using Spatially Structured Illumination
    (Academic Press, 2020) Ataç, Enes; Dinleyici, Mehmet Salih
    Optical fiber based sensor systems often utilize thin dielectric films coated on non-planar surfaces are needed to be inspected for quality assurance. However, non-destructive optical characterization of these films is not a simple method especially on curved large surfaces. In this study, we propose a real time procedure to estimate the optical properties of sub-wavelength transparent dielectric films coated on optical fibers. The paper includes developing a mathematical model and its experimental verification. The near field phase diffraction method is combined with the structured light illumination that is spatial modes of optical fibers to estimate the thickness of the phase object beyond the classical diffraction limits. Numerical simulations and experimental results show that the film thickness can safely be characterized up to one tenth of wavelength of interest via selective spatial field distribution determined according to the morphology of the thin film. The outcomes have good agreements with destructive Scanning Electron Microscope (SEM) measurements. © 2020 Elsevier Inc.
  • Conference Object
    All-Optical Switching Based on Grating Written Photorefractive Slab/Fiber Waveguide Coupler
    (Institute of Electrical and Electronics Engineers Inc., 2002) Dinleyici, Mehmet Salih
    Since all optical switching is a key element for all kinds of optical networks, great amount of works have been dedicated either for material researches or various waveguide structures. Generally speaking the switching time of devices based on photorefractive effect are rather slow for today's high capacity optical fiber networks. In the field of waveguide architecture various geometries have been proposed and investigated for grating assisted or guided optical coupling for the purpose of designing all-optical switch, adddrop multiplexers, filters etc.
  • Conference Object
    Citation - WoS: 3
    Citation - Scopus: 4
    Düşük Maliyetli Serbest-uzay Optik İletişim Sistemi Tasarımı
    (Institute of Electrical and Electronics Engineers Inc., 2004) Karatay, Okan; Dinleyici, Mehmet Salih
    hi recent years commercial and military interest in free-space optical communication (FSO) is growing due to the high bandwidths, portability and high security. Although the numerous advantages, atmospheric events such as attenuation and scintillation severely effects the link quality. Novel methods of mitigating atmospheric events were applied. Usage of large aperture lenses and high transmitted power according to decrease scintillation effects increases the system cost. Fresnel lenses, as an alternative to the classical optic system for mitigating scintillation effects would be a low-cost solution. As a result of the technological improvements on the output power and divergence angles of VSCEL (Vertical Cavity Surface Emitting Laser) enables high-speed cost effective FSO communication system design. In this research current applied FSO systems are analysed and fresnel lens optical system of alternative low-cost system designed.
  • Conference Object
    Citation - Scopus: 1
    3-D Switching Fabric Node Design
    (ACTA Press, 2004) Dinleyici, Mehmet Salih; Akın, Osman
    In this work we investigate an all-optical switching node that can be controlled by means of a transient grating, which is formed by interference of two Gaussian beams. This design considers 3-D architecture of switching fabrics.. real profile of Gaussian beams and fast switching time requirements. Four Wave Mixing (FWM) technique is applied in the evanescent field region of waveguide, showing chi((3)) nonlinearity. The formed grating is analysed by standart methods to obtain reflection coefficient and then coupling coefficient for power exchange between waveguides.
  • Conference Object
    Citation - Scopus: 1
    Lcd Arkaışık Modüllerinde Moire Etkisinin İncelenmesi
    (Institute of Electrical and Electronics Engineers Inc., 2007) Dinleyici, Mehmet Salih; Akın, Osman
    LCD panellerde, Sıvı Kristal (Liquid Crystal) camdan önce parlak ve homojen bir ışık dağılımı elde etmek için LCD Arkaışık Modülünün içinde Dağıtıcı tabaka, Dağıtıcı filmler ve Parlaklık Arttırıcı Film (Brightness Enhancement Film – BEF) kullanılır. Ancak modülün en üstünde kullanılan dağıtıcı film, ışığı dağıtmanın ve BEF’i korumanın yanında Moire Etkisini önlemek için de kullanılabilir. Bu çalışmada, bahsi geçen bu son dağıtıcı filmin Moire etkisinin yokedilmesi konusundaki rolü incelendi.
  • Conference Object
    Tam Optik Anahtarlama için Faz Analizi
    (IEEE, 2006) Dinleyici, Mehmet Salih; Akın, Osman
    In this work we investigate an all-optical switching node that can be controlled by means of a transient grating, which is formed by interference of two Gaussian beams. This design considers phase effect in the reflection of light from transient grating, real profile of Gaussian beams and fast switching time requirements. Four Wave Mixing (FWM) technique is applied in the evanescent field region of waveguide, showing ?(3) nonlinearity. The formed grating is analysed by standart methods to obtain the phase of diffracted light and reflection coefficients to find the power exchange between reflection orders. © 2006 IEEE.
  • Article
    Citation - WoS: 2
    Citation - Scopus: 2
    Investigating the Experimental Limits of the Brewster’s Angle Method
    (Türkiye Klinikleri Journal of Medical Sciences, 2018) Sümer, Can; Kuştepeli, Alp; Dinleyici, Mehmet Salih
    We present the method, analysis, and experimental results of the Brewster’s angle method commonly used for determining the refractive indices of optical films. We show the significance of the intersection of reflectance curves, in that the necessity for substrate refractive index and film layer thickness knowledge are both eliminated. We present the conditions for the existence of the second intersection of reflectance curves and introduce a method for determining the refractive index of the substrate layer by using the angular information alone. Analytical results reveal impressive practical sensitivity and accuracy limits for the method, where the experimental results also support the theoretical analysis.
  • Article
    Citation - WoS: 7
    Citation - Scopus: 7
    Demonstration of Pulse Controlled All-Optical Switch/Modulator
    (The Optical Society, 2014) Akın, Osman; Dinleyici, Mehmet Salih
    An all-optical pulse controlled switch/modulator based on evanescent coupling between a polymer slab waveguide and a single mode fiber is demonstrated. Very fast all-optical modulation/switching is achieved via Kerr effect of the nonlinear polymer placed in the evanescent region of the optical fiber. Local refractive index perturbation (δn = -1.45612 × 10 -5) on the thin film leads to 0.374 nW power modulation at the fiber output, which results in a switching efficiency of ≈1.5%.
  • Article
    Citation - WoS: 5
    Citation - Scopus: 7
    A Practical Approach for Optical Characterization of a Film Coated on the Optical Fiber
    (Academic Press Inc., 2017) Ekici, Çağın; Dinleyici, Mehmet Salih
    Phase Diffraction (PD) Phase Diffraction. which is a result of the interaction of light waves with a transparent object, is exploited to characterize precisely optical properties of dielectric films coated on the optical fiber without harming any feature of the sample. Typical fiber sensor applications require films coated on the side surface of the optical fiber and optical properties of that curved films are crucial for design purposes. In this study, three Polyvinyl Alcohol (PVA) films are prepared, their thicknesses are estimated based on the phase diffraction method by fitting experimental results with a mathematical model within 2.3% error. The outcomes of this practical method show good agreement with findings of the destructive Scanning Electron Microscopy (SEM) measurements. The method has the potential to allow real time monitoring abrupt changes of surrounding medium's properties and to examine coating quality (i.e. thickness uniformity) of the film.