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Permanent URI for this collectionhttps://hdl.handle.net/20.500.14288/3

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Department: search.filters.department.Department of PhysicsSubject: search.filters.subject.Telecommunications

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    Image reconstruction in frequency space using sinusoidal illumination patterns
    (IEEE, 2020) Aydın, Musa; Department of Physics; N/A; N/A; Department of Physics; Kiraz, Alper; Uysallı, Yiğit; Özgönül, Ekin; Morova, Berna; Faculty Member; PhD Student; PhD Student; Researcher; Department of Physics; College of Sciences; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; 22542; N/A; N/A; N/A
    Structured Illumination Patterns is an imaging technique used in microscopic imaging to achieve super-resolution image by exceeding the diffraction limit. In microscopic imaging, the light projected onto the sample to be imaged is modulated into two dimensional sinusoidal illumination patterns and the raw image is obtained. By using this technique, the image reconstruction algorithm applied to the raw images in the frequency space is provided to increase the resolution of the final image up to two times. In this study, to obtain the high resolution target image, convolution multiplication of the structured illumination patterns with a test image is applied and a moire fringe pattern is formed as a result of this product. Next, the steps of the structured illumination microscopy technique algorithm are described. Finally, the algorithm for image reconstruction in frequency space has been developed and the results are shown.
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    Elastic scattering from germanium microspheres in the terahertz region
    (IEEE, 2016) N/A; N/A; Department of Physics; Bukhari, Syed Sultan Shah; Chaudhry, Muhammad Rehan; Serpengüzel, Ali; PhD Student; PhD Student; Faculty Member; Department of Physics; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; 27855
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    Optofluidic applications using droplet resonators and optical fiber resonators coupled with tapered optical fiber waveguides
    (IEEE, 2017) N/A; Department of Physics; Kiraz, Alper; Faculty Member; Department of Physics; College of Sciences; 22542
    Sessile microdroplets of water and other polar liquids take almost spherical shapes when standing on a superhydrophobic surface. With their truncated microsphere geometry, they act as optical microcavities hosting whispering gallery modes. We achieved coupling to liquid droplet resonators kept in a controlled humidity chamber with optical fiber waveguides. In these experiments, quality factors exceeding 1 million were observed. A method for self-stabilization of the size of the droplet resonators was also demonstrated using a fixed wavelength heating laser in addition to the probe laser coupled to the same tapered optical fiber. Self-stabilization mechanism relied on the absorption resonances of the heating laser encountered by an initially condensating droplet.
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    Optofluidic dye lasers based on holey fibers: modeling and performance analysis
    (Institute of Electrical and Electronics Engineers (IEEE), 2018) Jonas, Alexandr; Buczynski, Ryszard; Department of Physics; N/A; Kiraz, Alper; Rashid, Muhammed Zeeshan; Faculty Member; PhD Student; Department of Physics; College of Sciences; Graduate School of Sciences and Engineering; 22542; N/A
    Holey optical fibers with air-filled openings can be turned into unconventional optofluidic components by selectively introducing a suitable liquid into their internal holes. Enhanced interaction between the light guided by the fiber and molecular species suspended in the confined liquid then forms the basis for designing unique optofluidic devices-filters, sensors, or lasers-whose operating characteristics are extremely sensitive to minute changes in the liquid composition. We present a comprehensive mathematical analysis of dye lasers based on suspended-core and hollow-core fibers, with aqueous solution of Rhodamine B dye injected into the internal holes of the fibers acting as the gain medium. Our model consists of coupled first-order differential equations that characterize the population of lasing levels and the variation of pump and signal laser powers along the fiber length in the steady state. We obtain optimum operating conditions of the proposed holey fiber dye lasers, such as the optimum fiber length and dye concentration, and compare their performance to conventional dye jet lasers. We conclude that the fiber variant of dye laser using the hollow-core fiber is superior in terms of low lasing threshold and high slope efficiency. The presented theoretical framework can find applications in designing practical holey fiber dye lasers serving as fiber-based alternatives of conventional dye jet lasers as well as novel biological/chemical sensors and bio-lasers.
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    Simulation of elastic scattering from a germanium microsphere in the near-ir
    (IEEE, 2016) N/A; N/A; Department of Physics; Çirkinoğlu, Hüseyin Ozan; Khan, Imran; Serpengüzel, Ali; Master Student; Master Student; Faculty Member; Department of Physics; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; 27855
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    Image reconstruction in frequency space using sinusoidal illumination patterns
    (Institute of Electrical and Electronics Engineers Inc., 2020) Aydın, Musa; Department of Physics; N/A; N/A; N/A; Kiraz, Alper; Morova, Berna; Özgönül, Ekin; Uysallı, Yiğit; Faculty Member; Researcher; PhD Student; PhD Student; Department of Physics; N/A; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); N/A; N/A; College of Sciences; N/A; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; 22542; N/A; N/A; N/A
    Structured Illumination Patterns is an imaging technique used in microscopic imaging to achieve super-resolution image by exceeding the diffraction limit. In microscopic imaging, the light projected onto the sample to be imaged is modulated into two dimensional sinusoidal illumination patterns and the raw image is obtained. By using this technique, the image reconstruction algorithm applied to the raw images in the frequency space is provided to increase the resolution of the nal image up to two times. In this study, to obtain the high resolution target image, convolution multiplication of the structured illumination patterns with a test image is applied and a moire fringe pattern is formed as a result of this product. Next, the steps of the structured illumination microscopy technique algorithm are described. Finally, the algorithm for image reconstruction in frequency space has been developed and the results are shown.