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3 Applications of Zero-Index Metamaterials
(a) Computational cell
(b) With cloak
(c) Without cloak
Fig. 3.8 a Electromagnetic cloaking by transformation optics. No shadow is cast. b Uncloaked
object casts shadow. The arrows indicate the direction of power flow
as that at the boundary of incidence. This property of zero-index metamaterials has
already been discussed in Chap. 2. To demonstrate the ZIM-based cloaking, we have
chosen rods-in-air-type zero-index metamaterial in which an optically large object
has been embedded (see Fig. 3.9a). The rods of the ZIM are made of silicon, and the
surrounding medium is air. The ZIM is meant to cloak the object from any incoming
radiation, thereby making it invisible. In Fig. 3.9b, the design of the computational
cell used for numerical analysis has been shown, with proper boundary conditions
and port locations. To thoroughly explain the cloaking effect of the ZIM, various
types of simulations have been performed (Fig. 3.9c–f). Firstly, the invariance of the
phase and the magnitude of the electric field throughout the zero-index metamaterial
have been shown in Fig. 3.9c. Please note that the phase with which the wave enters
the ZIM is the same as that with which it exits. It seems as if a part of the space has
vanished for the incoming wave, by the effect of ZIM. Interestingly, the metamaterial
continues to exhibit the same behavior even in the presence of an opaque object, if
the ZIM region is sufficiently large, thereby cloaking it from the incident wave.
Here we have used a 10 × 10 array of silicon cylinders. Figure 3.9d showcases the
electromagnetic cloaking effect of the zero-index metamaterial, in which the plane
wavefronts enter the ZIM and exit undistorted, without any shadow region being
formed. On the other hand, in the absence of the metamaterial, the cloaking effect
is absent too. Consequently, the plane wavefront gets distorted, and a shadow region
gets formed behind the object (Fig. 3.9e). This illustrates the effectiveness of the ZIM
in providing the cloaking effect. Finally, for the sake of comparison and confirmation,
we performed the computation using a homogeneous ZIM slab of the same size as
the previously used 10 × 10 array, perfect exhibition of cloaking (Fig. 3.9f) with
3 Applications of Zero-Index Metamaterials
(a) Computational cell
(b) With cloak
(c) Without cloak
Fig. 3.8 a Electromagnetic cloaking by transformation optics. No shadow is cast. b Uncloaked
object casts shadow. The arrows indicate the direction of power flow
as that at the boundary of incidence. This property of zero-index metamaterials has
already been discussed in Chap. 2. To demonstrate the ZIM-based cloaking, we have
chosen rods-in-air-type zero-index metamaterial in which an optically large object
has been embedded (see Fig. 3.9a). The rods of the ZIM are made of silicon, and the
surrounding medium is air. The ZIM is meant to cloak the object from any incoming
radiation, thereby making it invisible. In Fig. 3.9b, the design of the computational
cell used for numerical analysis has been shown, with proper boundary conditions
and port locations. To thoroughly explain the cloaking effect of the ZIM, various
types of simulations have been performed (Fig. 3.9c–f). Firstly, the invariance of the
phase and the magnitude of the electric field throughout the zero-index metamaterial
have been shown in Fig. 3.9c. Please note that the phase with which the wave enters
the ZIM is the same as that with which it exits. It seems as if a part of the space has
vanished for the incoming wave, by the effect of ZIM. Interestingly, the metamaterial
continues to exhibit the same behavior even in the presence of an opaque object, if
the ZIM region is sufficiently large, thereby cloaking it from the incident wave.
Here we have used a 10 × 10 array of silicon cylinders. Figure 3.9d showcases the
electromagnetic cloaking effect of the zero-index metamaterial, in which the plane
wavefronts enter the ZIM and exit undistorted, without any shadow region being
formed. On the other hand, in the absence of the metamaterial, the cloaking effect
is absent too. Consequently, the plane wavefront gets distorted, and a shadow region
gets formed behind the object (Fig. 3.9e). This illustrates the effectiveness of the ZIM
in providing the cloaking effect. Finally, for the sake of comparison and confirmation,
we performed the computation using a homogeneous ZIM slab of the same size as
the previously used 10 × 10 array, perfect exhibition of cloaking (Fig. 3.9f) with