Thesis (M.Sc.) - Cairo University - National Institute of Laser Enhanced Sciences - Department of Laser Applications in Environmental Metrology Photochemistry and Photobiology

Exploring of optical properties of metamaterials is one of the most hot topics in research today. In this work we aim at investigating different optical properties in optical range for different designs of metamaterials based on nanoparticles structures such as alternating layers of gold nano rods with gold nano spheres, alternating layers of gold nano rods with dielectric nano spheres, periodic rods only and periodic spheres only. As the design of a specific metamaterial requires the simulation of the material model structure, we established 3D-FDTD Matlab codes for theoretical investigation of optical properties of theses structures for wavelengths 0.25, 0.5, 0.75 and 1um. One of the most attracting results is the producing of new frequencies as a result of the propagation in the vicinity of the metallic nanoparticles in addition to those of incident ones. The produced frequencies are strongly related to the wave envelopes of the propagation. The presence of induced frequencies is verified experimentally. The transmission coefficients calculations showed the presence of band gap for wavelengths (n=0.5 and n=0.75om) for parallel and perpendicular polarization for the structure of the alternating layers of gold nano rods with the gold nano spheres. While this structure exhibit the maximum transmission for the wavelength of 1um. The real indices of refraction have distinctive values where negative values calculated for some structures' paths at n=0.75um and n=1um, while near zero refraction shown at n=0.5um and n=0.75um for other paths, as well high positive values achieved from sphere's paths of spheres only structures reaching up to 10.6. This indicates a very high anisotropy of the structures. The electric permittivity of some structures are also estimated showing their dependence on the ratio of wavelengths to the gap distances

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