Modeling And Simulation Of Novel Metamaterials At Optical Frequencies

Metamaterial is a type of material that is engineered to possess some particular properties those are not present in naturally-occurring materials.They are manufactured f om assemblies composed of different elements that are crafted out of composite materials.Examples of these composite materials are plastics and metals.Typically,the materials are organized in recurring patterns,using scales that less in size compared to the wavelengths of the occurrences that they are supposed to influence.Metamaterials that have the appropriate design tend to possess the ability to affect electromagnetic radiation waves or sound.Moreover,metamaterials can do this in a way that is not commonly seen in bulk materials.Metamaterials that show negative refraction index for specific wavelengths are seen to attract a considerable amount of research and studies.These materials are referred to as negative-index metamaterials.The main goal of this dissertation is the study of metamaterials with new geometrical shapes.Another purpose is to explore materials that have a negative refractive index by using one element and achieve negative permittivity and permeability.In this work,simulations are performed on various designs of metamaterials in the optical spectrum,specifically in the visible light.Research results in this dissertation can be summarized as follows:(1)A kind of core-shell metal-dielectric structure is presented in the visible light range for the isotropic negative refractive index.For the presented structure,it made of two nano-spheres(core and shell);the materials chosen in this paper were wood,oil,and silver metal.In this structure,it is found out that silver core covered with oil shell,wood shell coated silver core,silver shell coated wood core,and oil shell coated wood core exhibit negative refractive index in the visible light.Silver core covered with oil shell nanoparticles possess a high transmission inside the wavelength variety 550nm-680nm;in other words,excessive transmission for yellow and orange colors which leads us to consider that it should have the ability in filtering applications.For wood shell coated silver core nanoparticles,the simulation demonstrates that using wood as a dielectric shell can absorb up to 50%of light at ?=456.9nm.This mixture reflects less than 20%of light at 456.9nm.We believe that this structure has the potential to be used as a band-reject filter at ?=456.9nm,on the other hand,this structure can absorb up to 50%of light at ?=456.9nm which lead us to consider the possibility to use this structure with this specific mixture as an optical resonance metamaterial absorber.Silver shell coated wood core nanoparticles structure shows the ability to control reflection and absorption.Oil shell coated wood core nanoparticles,it is found that this structure can obtain 81%of reflectivity,1.56%of transmission,and 19%of absorbency at 382nm.Hence,this structure with this combination might have the potential to be used as a reflector of UV light in astronomical telescopes.Reflection spectra of the oil shell coated wood core nanoparticles for different oil coating radii are also studied.It is found out that reflection spectra show a dependency on the oil shell radius.(2)A new shape of metamaterials is studied at optical frequencies,which present properties of mercury(or quicksilver)metal as a metamaterial in the visible light.The design made from a box that's opened from the front and back,within this box there are arrays of nanowires made of mercury.It is showed that this new form possesses a negative magnetic permeability within the visible light that results in negative refractive index material,and the structure's absorption is enhanced by ever-changing the radius of the nanowires,so that this structure might be used in the industry of wearable products or filtering applications specifically as a stop-band filter.(3)The metamaterial properties of an epoxy resin material are studied,which has a periodic spherical structure at optical frequencies(specifically visible light).This material shows a negative refractive index at a specific frequency range with small values of the imaginary part,which allow the waves to propagate through the nanostructure.Also,it gives an excellent transmission in the cases of the radius(R=10,15,20,and 25nm).It is resulted that increasing the semidiameter of the spheres make the refractive index to move towards positive values;the same effect applied to the permittivity and the permeability.Increasing the radius of these nanoparticles,precisely when r=30nm,we create wide-band high permeability metamaterial,which might have the potential to be used in the technology of gas separation.The simulation is continued with the consideration of adding a substrate.The epoxy resin nanoparticles of 20nm radius and permittivity ?r=4,are positioned on a substrate of mica glass with effective thickness d=70nm and permittivity ?r=6.7 at visible light wavelengths.At some wavelengths,the real part of the refractive index is observed to be negative,where both the real components of permittivity and permeability are negative without the use of split-ring resonators and thin cables.(4)A chiral metamaterial is presented to exhibit giant circular dichroism in the range of mid-infrared.The structure is a 3D chiral structure operating in the mid-infrared region.The suggested structure may have prospective biosensing applications such as detection of Myoglobin,?-Chymotrypsin,and Concanavalin A in the mid-infrared spectrum.