Visible frequency range negative index metamaterial of hexagonal arrays of gold triangular nanoprisms

Spaces of electromagnetic and mechanical constitutive parameters for dissipative media with either positive or negative index

“…(2)-(5), without considering criteria based on the complexvalued refractive index n. We have also verified the consistency of this representation with the analysis of additional material parameters retrieved in the Gigahertz, 24,26,35 Terahertz, 36 and optical 34,37,38 regimes. In particular, all the couples of constitutive parameters associated with a negative refractive index 24,34,36,37 naturally belong to regions defined by Eqs.…”

Metamaterial study of quasi-three-dimensional bowtie nanoantennas at visible wavelengths

“…Conventional 2D bowtie nanoantennas are often fabricated in a single flat plane 8 21 22 , like the y-z plane in Fig. 1(a) .…”

“…Due to many applications in the fields of negative refractive index, invisibility cloaking, perfect lensing and superconductors, metamaterials have become one of the hottest fields of photonics 4 5 6 7 . According to the effective medium theory of metamaterials, the interior structure characteristic size of the medium must be in the nanometer scale when operating at visible wavelengths 8 9 . As experimentally fabricating of nanoscale metamaterials is one of the severe challenges, especially for fabrications with low-cost and facile processes, metamaterials have been limited to visible wavelengths 2 10 11 .…”

“…By numerical simulations, M. Giloan et al . have reported that 2D bowtie nanoantennas can be utilized as metamaterials in the visible range 8 . Magnetic fields of 2D bowtie nanoantennas have also been studied by some groups 17 18 19 .…”

“…3D metamaterials can be achieved using a “top-down” or a “bottom-up” fabrication approach. However, “top-down” fabrication approaches such as electron-beam lithography and focused ion-beam technology require expensive apparatuses and complicated processes 8 23 25 , which significantly limited the promotion of 3D metamaterials. Therefore, an effective fabrication approach with low-cost and facile processes is still challenging but very attractive and promising for nanostructures applied in visible regions, especially for 3D metamaterials.…”