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3 Applications of Zero-Index Metamaterials
3.2.3 Controlling the Tunneling Using Obstacles
Nguyen et al. [133] reported in 2010 that by including defects in zero-index metamaterials, their tunneling capability can be so efficiently controlled that total transmission or total reflection can be achieved. They used cylindrical defects of different
radii to demonstrate the effect of geometrical and material parameters of the obstacles on the tunneling characteristics. Figure 3.5 shows how the transmission can be
controlled by introducing defects inside an EMNZ medium, which has both and μ
close to zero. The equal values of and μ have been assumed so that their ratio, and
hence the impedance of the EMNZ medium is equal to 1. The medium on both sides
of the EMNZ medium has been chosen to be air. Such a medium is called matchedimpedance zero-index material (MIZIM). Figure 3.5a–c shows the magnetic field H z ,
the electric field E y , and the Poynting vector S x , respectively, for an incident wave
of frequency 15 THz. It can be observed that the field on the right-hand side of the
EMNZ medium is substantially lower compared to the left-hand side, which indicates
reduced transmission. There are three different defect objects of radii 4 µm, 8 µm,
and 12.4 µm and permittivity 3.66, 11.86, and 15.67, respectively. In the absence of
these defects, the wave is fully transmitted to the other side of the EMNZ slab.
The defect’s size and the defect’s material play a crucial role in deciding the
transmission. Here, the effect of both these quantities has been numerically analyzed
and the results have been presented in Fig. 3.6. Figure 3.6a shows the design of the
computational region, in which the air, the EMNZ, and the defect regions have been
depicted. The defect object is cylindrical and has been arbitrarily placed inside the
EMNZ medium. The radius and the permittivity of the defect have been varied
and the corresponding transmission coefficient has been calculated. The plots thus
obtained have been shown in Fig. 3.6b, c, from which it can be inferred that for
certain values of R and the transmission can be as high as 100% while for certain
other it can be reduced down to almost zero. Thus, we get that the transmission
characteristic of a zero-index medium can be arbitrarily controlled by introduction
defects of strategically chosen geometrical and material properties.
3.3 Electromagnetic Cloaking
Electromagnetic cloaking is one of the most fantastic phenomena achieved by metamaterials, in which a metamaterial cloak manipulates the path of light around the
cloaked object in such a way that the wavefront emerging out of the cloak reforms
into its original shape, thereby casting no shadow. Incident wave completely ignores
an optically large object and passes unaltered, if the object is cloaked [27, 134–147].
This application is a major reason for the popularity of metamaterial, besides negative refraction, as it seems straight out of science fiction. There are two ways to
electromagnetic cloaking: (1) by means of transformation optics; (2) by means of
zero refractive index.
3 Applications of Zero-Index Metamaterials
3.2.3 Controlling the Tunneling Using Obstacles
Nguyen et al. [133] reported in 2010 that by including defects in zero-index metamaterials, their tunneling capability can be so efficiently controlled that total transmission or total reflection can be achieved. They used cylindrical defects of different
radii to demonstrate the effect of geometrical and material parameters of the obstacles on the tunneling characteristics. Figure 3.5 shows how the transmission can be
controlled by introducing defects inside an EMNZ medium, which has both and μ
close to zero. The equal values of and μ have been assumed so that their ratio, and
hence the impedance of the EMNZ medium is equal to 1. The medium on both sides
of the EMNZ medium has been chosen to be air. Such a medium is called matchedimpedance zero-index material (MIZIM). Figure 3.5a–c shows the magnetic field H z ,
the electric field E y , and the Poynting vector S x , respectively, for an incident wave
of frequency 15 THz. It can be observed that the field on the right-hand side of the
EMNZ medium is substantially lower compared to the left-hand side, which indicates
reduced transmission. There are three different defect objects of radii 4 µm, 8 µm,
and 12.4 µm and permittivity 3.66, 11.86, and 15.67, respectively. In the absence of
these defects, the wave is fully transmitted to the other side of the EMNZ slab.
The defect’s size and the defect’s material play a crucial role in deciding the
transmission. Here, the effect of both these quantities has been numerically analyzed
and the results have been presented in Fig. 3.6. Figure 3.6a shows the design of the
computational region, in which the air, the EMNZ, and the defect regions have been
depicted. The defect object is cylindrical and has been arbitrarily placed inside the
EMNZ medium. The radius and the permittivity of the defect have been varied
and the corresponding transmission coefficient has been calculated. The plots thus
obtained have been shown in Fig. 3.6b, c, from which it can be inferred that for
certain values of R and the transmission can be as high as 100% while for certain
other it can be reduced down to almost zero. Thus, we get that the transmission
characteristic of a zero-index medium can be arbitrarily controlled by introduction
defects of strategically chosen geometrical and material properties.
3.3 Electromagnetic Cloaking
Electromagnetic cloaking is one of the most fantastic phenomena achieved by metamaterials, in which a metamaterial cloak manipulates the path of light around the
cloaked object in such a way that the wavefront emerging out of the cloak reforms
into its original shape, thereby casting no shadow. Incident wave completely ignores
an optically large object and passes unaltered, if the object is cloaked [27, 134–147].
This application is a major reason for the popularity of metamaterial, besides negative refraction, as it seems straight out of science fiction. There are two ways to
electromagnetic cloaking: (1) by means of transformation optics; (2) by means of
zero refractive index.