Figure 1

(Color online) Geometry of the superlens: an array of crossed metallic wires tilted by $\pm 45°$ with respect to the interfaces is embedded in a host material slab with thickness $L$ and relative permittivity ${\epsilon }_h$. The wires are contained in planes parallel to the $xoz$ plane. Each wire mesh is arranged in a square lattice with lattice constant $a$. The wires in adjacent planes are orthogonal and are spaced by $a/2$.Reuse & Permissions

Figure 2

(Color online) Amplitude of the transmission coefficient as a function of normalized frequency for different lattice constants, $a$, and a fixed slab thickness $L$. Solid lines represent the analytical model; dashed lines represent full wave simulations obtained with CST MICROWAVE STUDIO (Ref. 13). The angle of incidence is ${\theta }_i=15°$, the radius of the wires is $r_w=0.05a$, and the permittivity of the substrate is ${\epsilon }_h=1$.Reuse & Permissions

Figure 3

(Color online) Step-by-step construction of the crossed wire mesh [panel (c)] starting from an array of parallel wires tilted by an angle $\alpha$ with respect to the interface [panel (a)]. The incoming wave propagates along the normal direction and the wires stand in air. In order to delay the wave supported by the structure of panel (a), one can add suitable inclusions to the material (small wire dipoles) [panel (b)]. These inclusions will partially block the path of propagation and in this way increase the effective index of refraction of the composite material. By adding many of such wire dipoles we arrive at the configuration of panel (c).Reuse & Permissions

Figure 4

(Color online) Amplitude of the transmission coefficient as a function of the normalized transverse wave vector, $k_y$, for different frequencies of operation $\omega$ and a fixed thickness $L$ of the material slab. Notice that for $k_{y}c/\omega >1$ the incoming wave is an evanescent mode, whereas if $\left|k_{y}c/\omega \right|<1$ the incoming wave is a propagating plane wave. The lattice constant is $a=L/10$, the radius of the PEC wires is $r_w=0.05a$, and ${\epsilon }_h=1.0$. Solid lines represent the analytical model; dashed lines represent full wave simulations obtained with CST MICROWAVE STUDIO (Ref. 13).Reuse & Permissions

Figure 5

(Color online) Amplitude of the transmission coefficient as a function of the normalized transverse wave vector, $k_y$, for the frequencies of operation 5, 10, and 15 THz, and for a material slab with thickness $L=2.9$, 1.4, and $0.95\mu \text{m}$, respectively (thus $L=0.3c/\omega$ in all the cases). The lattice constant is $a=L/10$, the radius of the silver wires is $r_w=0.05a$, and ${\epsilon }_h=1.0$. Solid lines represent the analytical model; dashed lines represent full wave simulations (Ref. 13). The inset represents the geometry of the artificial material slab.Reuse & Permissions

Figure 6

(Color online) Amplitude of the normalized electric field imaged by the superlens for a material slab with: (i) (left-hand side panel, $y<0$) $L=0.3{\lambda }_0/2\pi$, $a=L/10$, $r_w=0.05a$, and ${\epsilon }_h=1$; and (ii) (right-hand side panel, $y>0$) $L=0.1{\lambda }_0/2\pi$, $a=L/20$, $r_w=0.05a$, and ${\epsilon }_h=1$. Solid black line: electric-field profile in the absence of the metamaterial slab. Solid red (light gray in grayscale) line: image profile for an infinitely extended metamaterial slab; this curve was calculated using the analytical model [Eq. (6)]. Dashed red (light gray in grayscale) line: image profile calculated using a full wave numerical method [Method of Moments (MoM)] that takes into account all the fine details of the microstructure of the artificial material for a substrate with finite width $W$ along $y$, with $W=2.15{\lambda }_0$ and $0.96{\lambda }_0$ for cases (i) and (ii), respectively. The inset represents the geometry of the problem: an electric line source is placed a distance $d_1$ above the superlens, and the observation plane is located at a distance $d_2$ below the lens. For both examples, $d_1=d_2=0.04{\lambda }_0$. The relative electric-field amplitude with respect to the case in which the superlens is removed (black curve) is (a) infinite substrate: 0.25 (case i) and 0.17 (case ii); and (b) finite substrate: 0.28 (case i) and 0.19 (case ii).Reuse & Permissions

Figure 7

(Color online) Amplitude of the normalized electric field $E_x$ for a superlens configuration with the same geometry as case (i) of Fig. 6, except that the width of the lens along the $y$ direction is $W=0.39{\lambda }_0$.Reuse & Permissions

Figure 8

(Color online) Amplitude of the normalized electric field imaged by a superlens characterized by $L=0.3{\lambda }_0/2\pi$, $a=L/10$, $r_w=0.05a$, and ${\epsilon }_h=1$ at the reference wavelength ${\lambda }_0$. The line source is placed at a distance $d_1=0.8L$ above the superlens, and the observation plane is at a distance $d_2=0.8L$ below the superlens. Solid black line: electric-field profile in the absence of the metamaterial slab at $\lambda ={\lambda }_0$. Solid red (light gray) line: electric-field profile for a superlens made of PEC wires at $\lambda ={\lambda }_0$. (i) (Left-hand side panel, $y<0$) electric-field profile for PEC wires at $\lambda =0.9{\lambda }_0$ and $1.1{\lambda }_0$. (ii) (Right-hand side panel, $y>0$) electric-field profile for silver wires at ${\lambda }_0=30$ and $60\mu \text{m}$.Reuse & Permissions