Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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Author: search.filters.author.Ateş, SerkanPublisher: search.filters.publisher.01. Izmir Institute of Technology

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Now showing 1 - 4 of 4
  • Master Thesis
    Efficient Photon Pair Generation for Quantum Information Technologies
    (01. Izmir Institute of Technology, 2024) Ateş, Serkan; Ateş, Serkan; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of Technology
    Bu tez, dört dalga karışım (FWM) süreci yoluyla görünür dalga boylarında foton çiftleri üretmek için kullanılan dalga kılavuzu ve halka rezonatörün tasarım parametreler- ine odaklanmaktadır. Tezin amacı, görünür dalga boylarında foton çiftleri üretmektir ve bu fotonları algılamak için görünür dalga boyunda çalışan fotodedektörler kullanılmak- tadır. Bu dedektörler, telekomünikasyon muadillerine kıyasla daha iyi foton algılama ar- alıgı, daha düşük karanlık sayım ve hızlı tepki süresi sunmaktadır. Ayrıca, görünür dalga boyundaki fotonlar serbest uzay iletişiminde daha etkilidir. Foton çift üretimi için Si3N4 dalga kılavuzu veya SiO2 tabakası üzerindeki halka rezonatör gibi bir fotonik platform tercih edilmektedir. Bu platformlar, CMOS teknolo- jilerini kullanma ve oda sıcaklıgında çalışma gibi avantajlar sağlar. Si3N4 malzemesinin tercih edilme nedeni, iki foton emilim sürecinden kaçınmaktır. Si bazlı kaynaklar, bant enerjileri nedeniyle iki foton emilim süreci sergilerken, Si3N4 kullanımı bu sorunu ortadan kaldırır. Tezde, dalga kılavuzunun boyutları faz uyumu koşulunu sağlamak amacıyla tasar- lanmış ve dispersiyon özellikleri incelenmiştir. Belirlenen boyutlara göre tasarlanan halka rezonatör, spektral özellikleri açısından verimli foton çift üretimi için analiz edilmiştir.
  • Master Thesis
    Theoretical Investigation of Structural, Vibrational, Electronic, and Elastic Properties of Ultra-Thin Anisotropic Materials
    (01. Izmir Institute of Technology, 2024) Doğan, Kadir Can; Ateş, Serkan; Yağmurcukardeş, Mehmet; Yağmurcukardeş, Mehmet; Ateş, Serkan; 04.04. Department of Photonics; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of Technology
    Dimensional reduction in materials leads to significant improvements and changes in various properties due to quantum phenomena and intense confinement of electrons. Since the separation of graphene from bulk graphite in 2004, many different materials with layered bulk structures have been experimentally introduced into the literature, including hexagonal boron nitride (BN), transition metal dichalcogenides (TMDs), and in-plane anisotropic monolayer black phosphorus (BP). Among ultra-thin materials, anisotropic materials have attracted attention due to their distinct orientation-dependent vibrational, electronic, optical, and mechanical features and have been shown to have high potential for special applications such as polarization-sensitive photodetectors, orientation-dependent optoelectronic devices, and orientation-sensitive sensors. The aim of this thesis is to predict the stable structures of ultra-thin anisotropic materials such as HfTe5, TiX5, TaX3 (X:S, Se, Te), bismuthene and magnetic MnPS3 nanoribbons and to understand their structural, magnetic, vibrational, electronic, optical and elastic properties on a physical basis by performing density functional theory (DFT)-based first-principles calculations. Preliminary data via STM images are presented for the potential experimental characterization of possible defects and oxidized structures of the single-layer HfTe5, whose predicted stable structure. The existence of stable structures of titanium-based penta-calcogenides is predicted and the direction-dependent properties of the stable phases are investigated. The dynamic stability of Ta-based trichalcogens exhibiting anisotropy different from TiS3 and ZrS3 has been investigated and their crystal-orientation dependent elastic properties are analysed. In addition, in the tilted α-bismuth known as the α phase, the identification of the external strain direction through the Raman spectrum is examined. The reduction of in-plane anisotropy to 1 dimension is studied through the edge type- and width-dependent properties in magnetic MnPS3 nanoribbons. Our findings are important for the prediction of novel anisotropic materials.
  • Master Thesis
    B92 Based Quantum Key Distribution With Faint Pulsed Laser
    (01. Izmir Institute of Technology, 2021) Ateş, Serkan; Çakır, Özgür; Ateş, Serkan; Çakır, Özgür; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of Technology
    In quantum key distribution (QKD), photons are used to share the key between the transmitter and receiver, and in principle, single photon sources should be used to create a secure communication channel. Nowadays, attenuated laser sources are used in many studies. While it is practical to use attenuated laser pulses for QKD system, it poses many safety issues due to the possibility of multiple photons in the laser pulses. In addition, the key rate is waived to increase the level of security. However, the use of single photon sources is not as easy and practical as using attenuated laser sources. Today, studies of single photon sources to be used for QKD continue. In order for these single photon sources to be used actively, a photon source that operates at room temperature, operates in a wide band-gap range for different areas of use (underwater, optical fiber-based and free space) and can be excited at high speed is required. Since hBN defect centers are a material that can produce single photons at room temperature and have a wide band gap, it seems very ideal for these studies. In this thesis, studies have been carried out on the realization of the protocol, which is a part of QKD, with solid-state materials that produce single photons. In the studies, a key was produced with a faint pulsed laser. Also, data is encrypted using the key of the transmitter. Then the data is successfully decrypted with the key measured by the receiver.
  • Master Thesis
    Optical Spectroscopy of Single Defects in Hexagonal Boron Nitride
    (01. Izmir Institute of Technology, 2021) Ateş, Serkan; Birinci, Ayşenur; Ateş, Serkan; 01. Izmir Institute of Technology; 04.05. Department of Pyhsics; 04. Faculty of Science
    Single photon sources are main component for several applications in quantum information technologies. Hexagonal boron nitride (hBN) is a suitable material to create heterostructures with two dimensional materials. It is a popular two dimensional material and single photon source due to having stable and bright emission in visible range. In this thesis, optical properties of single defects in bulk hBN were investigated. Defects have been selected using the micro-Photoluminescence setup, and it was observed that the defects have high degree of polarization and show typical optical saturation behavior. Time-resolved photoluminescence measurements were done by time-correlated single photon counting. Single photon nature of generated light from individual defects were demonstrated using Hanbury-Brown and Twiss interferometer.