Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Improving Doppler Radar Performance through Optically-Reconfigurable Unequal Power Division with Semi-Analytical Approach(Taylor & Francis Ltd, 2025) Karatay, Anil; Atac, Enes; Dinleyici, Mehmet Salih; Yaman, FatihThe improvement of the signal-to-noise ratio (SNR) of Doppler radar systems, enabling the detection of targets at greater ranges even with limited power, has been a longstanding focus of research. However, while key limitations such as low target reflectivity and environmental interference are often addressed, the impact of efficient use of the input power remains an overlooked, yet crucial factor in overall sensitivity. Additionally, the power allocation needs to be examined from an analytical perspective for further enhancement. In this study, we present a novel measurement approach, utilizing both semi-analytical analysis and experimental methods, to improve the performance of a dual-antenna CW Doppler radar through the use of an optically reconfigurable unequal microwave power divider which provides well-directed power utilization. Comprehensive grid searches, supported by an analytical approach and considering various loss and noise scenarios, demonstrate the capability of the proposed reconfiguration method. In the Doppler radar experiments where the pendulum and servo motor were used as targets, an SNR increase of 3.04 and 2.11 dB in the radar signal was observed with the proposed method, respectively. This noticeable improvement in the SNR of the time-frequency plots indicates an enhancement in the measurement performance. The unequal power allocation enabled continuous detection of target motion with minimal signal loss, lowering the minimum detectable power level by more than 2 dB compared to the equal power division case. The experimental results show that integrating an optically reconfigurable microwave power divider into the Doppler radar system increases precision in velocity measurements.Article Functional Manipulation of Nonspherical Nanoparticles With Cascaded Reconfigurable Modules(Elsevier, 2025) Arslanyurek, Seyma; Dinleyici, Mehmet SalihSelective nanoparticle sorting is essential for applications requiring monodisperse distributions, yet conventional methods lack adaptability for shape-based separation. This study introduces a reconfigurable optical manipulation technique that dynamically sorts spherical and non-spherical nanoparticles using cascaded modules based on evanescent fields. Optical forces were calculated using the Discrete Dipole Approximation (DDA) method, enabling the modeling of various particle shapes and accurately capturing rotational and translational movements. Two cascaded strategies are proposed: the first approach enables fluid-assisted filtration by selectively trapping spherical particles while allowing non-spherical ones to be carried away by the flow. The second strategy first induces the rotational alignment of particles and then employs a trapping mechanism that selectively retains specific geometries, enabling the separation of spherical and non-spherical nanoparticles. Unlike traditional approaches, this method enables high-precision, shape-selective separation without external flow modifications. The results demonstrate unprecedented control and efficiency in nanoparticle sorting, offering a scalable, high-throughput solution for microfluidic and optofluidic applications.Article Citation - WoS: 2Citation - Scopus: 2Subwavelength Thickness Characterization of Curved Dielectric Films Exploiting Spatially Structured Entangled Photons(Optica Publishing Group, 2023) Ataç, Enes; Dinleyici, Mehmet SalihPrecise determination of thin dielectric film optical properties is a critical issue for fiber optic sensor technologies. However, conventional methods for the optical characterization of these films not only are generally complex and tedious processes on curved surfaces but also require well-calibrated and overly sophisticated devices. We, on the other hand, propose a novel and practical quantum-based phase diffraction scheme to characterize the thickness of ultra-thin transparent dielectric films coated on an optical fiber beyond the classical diffraction limits in this paper. The approach is implemented by evaluating the effect of thickness variations on the highly visible two-photon diffraction pattern's zero crossings and amplitudes. The mathematical model and numerical simulations con-tribute to a better understanding of how the spatially structured entangled photons improve thickness precision with the help of intensity correlations and a confocal aperture. To prove the impact of the proposed system, it is compared with the classical phase diffraction method in the literature via simulations. According to the results, the thickness of the transparent dielectric films can be accurately estimated below one-twentieth of the wavelength of interest. & COPY; 2023 Optica Publishing GroupConference Object Citation - Scopus: 13-D Switching Fabric Node Design(ACTA Press, 2004) Dinleyici, Mehmet Salih; Akın, OsmanIn 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.