Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 21Citation - Scopus: 28Non-Iridescent Structural Colors From Uniform-Sized Sio2 Colloids(Elsevier Ltd., 2018) Topçu, Gökhan; Güner, Tuğrul; Demir, Mustafa Muammer; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyStructural colors have recently attracted interest from diverse fields of research due to their ease of fabrication and eco-friendliness. These types of colors are, in principle, achieved by periodically arranged submicron-diameter colloidal particles. The interaction of light with a structure containing long-range ordered colloidal particles leads to coloration; this usually varies depending on the angle of observation (iridescence). However, the majority of the applications demand constant color that is independent of the viewing angle (non-iridescence). In this work, silica colloids were obtained using the Stöber method at different sizes from 150 to 300 nm in an alcoholic dispersion. The casting of the dispersion on a substrate leaves behind a photonic crystal showing a colorful iridescent film. However, centrifugation and redispersion of the SiO2 particles into fresh solvent may cause the formation of small, aggregated silica domains in the new dispersion. The casting of this dispersion allows for the development of photonic glass, presumably due to the accumulation of aggregates showing stable colloidal film independent of viewing angle. Moreover, depending on the size of the silica colloids, non-iridescent photonic glasses with various colors (violet, blue, green, and orange) are obtained.Article Citation - WoS: 12Citation - Scopus: 12High Transmission Through a 90° Bend in a Polarization-Independent Single-Mode Photonic Crystal Waveguide(The Optical Society, 2015) Erol, Adem Enes; Sözüer, Hüseyin Sami; Sözüer, Hüseyin Sami; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyWe propose a polarization-independent single-mode waveguide, using a two-dimensional square photonic crystal with a complete band gap. The waveguide is tuned such that both TE and TM modes have the same group velocity and zero group velocity dispersion at the centergap frequency. We also present results for a 90° bend with transmission values of 98% for both modes.Article Citation - WoS: 8Citation - Scopus: 10Design of Dual-Mode Dual-Band Photonic Crystal Bandpass Filters for Terahertz Communication Applications(John Wiley and Sons Inc., 2015) Karakılınç, Özgür Önder; Dinleyici, Mehmet Salih; 03.05. Department of Electrical and Electronics Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyIn this study, Photonic Crystal (PhC) dual-mode dual-band bandpass filter is designed and its transmission characteristics are investigated for various configurations. PhC resonator structure is formed by a point defect microcavity that is equipped with one large and three smaller auxiliary perturbation rods. Degenerate modes at each band may also be excited by changing the structure properties of the perturbation. Plane wave expansion method and Finite Difference Time-Domain method are used to analyze the device characteristics. Proposed dual-band dual-mode PhC filter structure can effectively be used for terahertz communication applications.Article Citation - WoS: 3Citation - Scopus: 4Photonic Crystal Assisted 90° Waveguide Bend(World Scientific Publishing Co. Pte Ltd, 2011) Sözüer, Hüseyin Sami; Şengün, Hediye Duygu; Sözüer, Hüseyin Sami; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyThe 90° waveguide bend is an important component of optical circuit applications. We propose several models for such a bend, some of them assisted by a two-dimensional photonic crystal with a bandgap in the desired range of operating frequencies. We show that a photonic crystal assisted bend reduces bending loss by several orders of magnitude for transverse electric modes. © 2011 World Scientific Publishing Company.Article Citation - WoS: 14Citation - Scopus: 18Robustness of One-Dimensional Photonic Band Gaps Under Random Variations of Geometrical Parameters(American Physical Society, 2005) Sözüer, Hüseyin Sami; Sevim, Koray; Sözüer, Hüseyin Sami; Sevim, Koray; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyThe supercell method is used to study the variation of the photonic bandgaps in one-dimensional photonic crystals under random perturbations to thicknesses of the layers. The results of both plane wave and analytical band structure and density of states calculations are presented along with the transmission coefficient as the level of randomness and the supercell size is increased. It is found that with the supercell size fixed at 1024 unit cells, higher bandgaps disappear first as the randomness is gradually increased. The lowest bandgap is found to persist up to a randomness level of 55%. However, as the supercell size is increased all bandgaps are observed to approach pseudogaps but with very low density of states. It is shown that harmonics of a relatively small cluster of closely spaced defects largely account for the bulk of the modes that populate the photonic bandgaps.