Subwavelength imaging with composite metamaterials

Abstract

After reviewing the requirements, which has to be satisfied by a metamaterial based sub-wavelength imaging systems a thin films lens is reported herein. The material of the lens is a composite of spherical Ag nanoparticles embedded in SiO 2 host material. The image of the lens is calculated, by solving the Maxwell equations, with the Transfer Matrix method. The procedure applies Maxwell-Garnet mixing rule and high frequency effective medium theory to calculate the electromagnetic parameters of the composite material. The formula of the composite material, the optimum working frequency and the thicknesses of the layers are determined by minimizing the absolute difference of the field distribution in the source and image planes. The details of the design procedure are presented and optimized configurations obtained under different constrains are discussed. The main advantage of the composite lens is that it can eliminate the hotspots present in the images of metallic superlens.

Calculation of the Image of Extended Objects Placed Behind Metamaterial Slabs

“…However, the FDTD method is memory and time consuming when subwavelength metallic structures such as metamaterials are simulated. Taking the advantage that the effective parameters are already known, the Transfer Matrix Method [16,34] can provide a much more efficient simulation tool. We developed a modified formulation of the method, where the transfer function is calculated with the dispersion relation introduced in the previous section and illustrated for the fishnet type metamaterial in Fig.…”

“…3(b). The 2D calculations are performed in a configuration similar to [16], assuming that the metamaterial slab has an infinite extent in lateral directions. It is also assumed that TE and TM modes of the electromagnetic waves can be considered separately, and thus the electric or the magnetic field can be handled as a scalar field.…”

“…where d is the thickness of the slab, ξ(k x ) the generalized wave impedance and k z (k x ) the normal wave number in the medium that corresponds to k x [16,31]. This transfer function is calculated from the continuity conditions of the electromagnetic field components at the interfaces between different media and provides a steady state solution.…”

“…A number of novel imaging phenomena that cannot be achieved with classical optics were already demonstrated with metamaterials, such as subwavelength imaging [2,[12][13][14][15][16], aberration free focusing [17,18] and focusing without an optical axis [13,14,[19][20][21][22][23]. The last property allows the focusing of the whole scene behind a metamaterial slab into an image space.…”

From Flexible and Stretchable Meta-Atom to Metamaterial: A Wearable Microwave Meta-Skin with Tunable Frequency Selective and Cloaking Effects

“…Metamaterials have attracted considerable attention due to their inaccessible electromagnetic (EM) properties that can be hardly found in natural materials. The unique properties of negative permittivity, negative refractive index, and index close to zero 1 2 3 4 5 6 7 8 9 10 11 12 , allow metamaterials to be employed in many emerging applications such as sub-wavelength resolution imaging 13 14 , filtering 15 , and cloaking 16 17 18 19 . Compared to conventional microwave filters, metamaterial-based counterparts have demonstrated the potential to obtain compact sub-wavelength size and left-handed behaviors.…”