Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Improving Coupling Efficiency by Using Adiabtic Transition in Photonic Crystal Waveguides(Izmir Institute of Technology, 2012) Çetin, Zebih; Sözüer, Hüseyin Sami; Sözüer, Hüseyin Sami; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyPhotonic crystal waveguides (PhCWGs), designed by removing one or more slabs from a perfectly periodic structures, are possibly future optoelectronic circuit elements that promising a good ability to confine light in a direction and allowing it to propagate in other direction. One of the problem in their application is the coupling from a PhCWG to a completely different structure. This difficulty arrives from sudden change in structure's geometry. In this thesis, to over come this difficulty we used a transition region between two photonic crystal structures that have completely different geometrical parameters. According to our simulation results we find that by using transition region, coupling can be achieved almost without any loss.Master Thesis Photonic Crystal Assisted L-Shaped Waveguide Bend(Izmir Institute of Technology, 2009) Şengün, Hediye Duygu; Sözüer, Hüseyin Sami; Sözüer, Hüseyin Sami; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyPhotonic crystals are periodic dielectric structures. This periodicity allow us to manipulate light in ways that have not been possible before. As a result, photonic crystal waveguide components play a significant role in integrated optical circuit design because waveguides allow only certain electromagnetic wave modes to propagate inside the structure. There are many corresponding applications that rely on total internal reflection. However, with total internal reflection, there is a problem in guiding light through sharp corners, large optical losses occur around tight curves with a small bending radius. A simple explanation for these losses is that the angle of the incident light too low for total internal reflection when wave turns through a sharp corner. Thus, an unacceptable fraction of the electromagnetic energy is radiated out of the waveguide. To overcome this difficulty, in this thesis, we demonstrate a novel method for guiding light through sharp corners, using a 1 photonic crystal slab waveguide for the straight sections, and assisted by 2D Line Defect Waveguide at the corners.Plane Wave Method and Supercell Method are used to Figure out parameters and obtain the guided mode for our proposed structure. Then, numerical simulations (FDTD) reveal nearly perfect transmission at certain frequency ranges. Also, in this thesis different corner elements are used to show highly efficient transmission of light through sharp corners. Thus, light can be guided through a 90. corner, almost without loss, by using different corner elements. "Crystals are like people, it is the defect in them which tend do make them interesting". Colin Humphreys.Master Thesis Frequency Splitting With Two Dimensional Triangular Photonic Crystal(Izmir Institute of Technology, 2009) Erol, Adem Enes; Sözüer, Hüseyin Sami; Sözüer, Hüseyin Sami; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyPhotonic crystals are periodically arranged dielectric materials. If the periodicity is broken along a line, i.e. a line defect is formed, then the line defect can behave like a waveguide. In this thesis, a frequency splitting device for electromagnetic waves is designed and tested theoretically using line defect waveguides. The theoretical design of the waveguides is accomplished using the plane wave expansion and the supercell method. The testing is done by the finite difference time domain method. Frequency mixing and splitting, or multiplexers and demultiplexers as they are known in industry, for electromagnetic waves are important since they lead to a multiplication in capacity for optical communications. Multiplexers and demultiplexers have been in use for a long time. However, designing photonic crystal multiplexers has a history of about ten years. In this thesis, a new photonic crystal demultiplexer design is suggested using photonic crystal line defect waveguides.