negative refraction index nanoscale-metamaterial at visible frequencies
Alkim Akyurtlu, Electrical and Computer Engineering
There has been interest in the Negative Refraction Index (NRI) material at optical frequencies. There are two approaches to optical frequencies. 1)Volumetric structure: it is based on the spherical structure. It consists of two dielectric mediums : MgB2 (Host) and SiC (Spherical Inclusions). The MgB2 gives the negative permittivity in some frequency range. The spherical inclusions of SiC give the negative permeability within another frequency range. The NRI was achieved within the visible region by the adjustment of the radius of the SiC sphere and the fill factor. The adjustment of fill factor and the radius of SiC sphere are the factors of generating NRI material at optical frequency range. The advantage of this structure is that this nanoscale metamaterial is isotropic and low loss. 2)Planar structure: it is applying the structure such as Split Ring Resonator (SRRs) that works in the Microwave region, Therahertz, and Infrared regions by generating the same structure in smaller scale. By making them in nanoscale and stacking layers of them, we can have the NRI material at optical frequency range. However, the misalignment of SRRs can affect the performance of the metamaterial. We need to investigate the performance of the misalignments. Due to the development of nanotechnology, we can use the Nanometer Pattern Generation System (NPGS) or Molecular Lithography to make the nanoscale structures.