Design and Optimization of Nanoantennas for Nano-Optical Applications

Işıklar, Göktuğ
In this study, design and simulation of plasmonic nanoantenna structures to obtain high power enhancement capabilities at optical frequencies, as well as utilization of nanoantennas for imaging and sensing applications are presented. Plasmonic characteristics of nanoantennas, which depend on many parameters, such as material, frequency, geometry, and size, are investigated in detail via computational analyses of various nanoantenna structures. Numerical solutions of electromagnetic problems are performed by using surface-integral-equation formulations that are suitable for plasmonic objects, while the simulations are accelerated, where necessary, by employing the multilevel fast multipole algorithm. Various nanoantenna designs, including slitted structures and novel geometries obtained via shape optimization, are studied and compared with each other and with examples from the literature. Numerical analyses demonstrate superior properties of different nanoantenna designs depending on the frequency. In order to exemplify the applications that nanoantennas can be used for practical purposes, plasmonics structures with high optical sensitivities are designed by using bowtie geometries for particle sensing and nano-optical imaging applications. In this context, computational analyses of detection of nanoparticles with different shapes, sizes, and electrical properties are presented. Numerical results demonstrate the feasibility of particle detection and identification with both nanoantenna arrays and improved nano-holes.


Design and Simulation of Passive Reflecting Surfaces for 5G Applications
Karaova, Gokhan; Ergül, Özgür Salih (2021-01-01)
Design and simulation of passive reflectors to be used in 5G applications are presented. An optimization environment is constructed based on genetic algorithms (GAs) and a full-wave solver to obtain compact reflectors that possess various reflection characteristics in accordance with given design specifications. In addition to their triangulated models for simulations, reflectors are represented by Bezier surfaces on the optimization side to reach smooth designs that are suitable for fabrication. A multigri...
Computational simulation and realization of three-dimensional metamaterials with various exotic properties
İbili, Hande; Ergül, Özgür Salih; Department of Electrical and Electronics Engineering (2019)
In this study, computational analysis and realization of three-dimensional metamaterial structures that induce negative and zero permittivity and/or permeability values in their host environment, as well as plasmonic nanoparticles that are used to design metamaterials at optical frequencies are presented. All these electromagnetic problems are challenging since effective material properties become negative/zero, while numerical solvers are commonly developed for ordinary positive parameters. In real life, t...
Rigorous designs of nano-optical couplers and absorbers with photonic crystals involving irregular arrays and nonidentical elements
Yazar, Şirin; Ergül, Özgür Salih; Department of Electrical and Electronics Engineering (2021-9)
This thesis presents design and analyses of compact and effective nano-optical couplers and absorbers based on photonic crystals. Single-input and double-input nano-optical couplers that provide electromagnetic wave transmission in desired directions are designed, and important parameters regarding their transmission efficiency are investigated. These designs are further cascaded by adding one after another to create nano-optical transmission systems, whose transmission characteristics are also examined. In...
Development of D -type fiber optic sensors for detection of refractive index variation in evanescent wave field /
Güleryüz, Burcu; Durucan, Caner; Aslan, Mustafa M.; Department of Metallurgical and Materials Engineering (2014)
The purpose of this study is to design, construct, develop and test D-type multimode fiber optic (F/O) sensors based on evanescent wave field sensing. A comprehensive work has been performed both theoretically and experimentally using a geometrical modification approach to improve the sensors response in different manners for detecting the refractive index (RI) variations and bio-molecular interactions in aqueous environment. In this study, the D-type F/O sensors performance was improved utilizing optical w...
Design and implementation of magnetic field sensors for biomedical applications /
İnan, Ulaş Can; Gençer, Nevzat Güneri; Department of Electrical and Electronics Engineering (2015)
In this work, firstly the magnetic sensor types and their feasibility for biomedical applications are investigated. Then the air-cored induction coil sensor is chosen due to its advantages. Afterwards the usage of induction coils combined with amplifiers and connection types are studied. The biomedical applications requiring the use of magnetic field sensors are introduced. One of them, Lorentz Field Electrical Impedance Tomography (LFEIT) is explained in detail and experimental work is done for this applic...
Citation Formats
G. Işıklar, “Design and Optimization of Nanoantennas for Nano-Optical Applications,” M.S. - Master of Science, Middle East Technical University, 2020.