Fig. 1. (a) Schematic of a deep-subwavelength 2D all-dielectric composite structure (left), which generally can be treated as a continuous effective medium (right). (b)–(d) Snapshots of (b) Ez, (c) Ex, and (d) |E| when a TM-polarized wave is normally incident from the free space on the left side. The composite is composed of a host with εh=2 and three inclusions with relative permittivities of 1, 5, and 3, respectively. The working wavelength is λ=125h. (e) Transmittance through the actual composite (lines) and its effective medium model (dots) by assuming N layers of unit cells along the propagation direction.

Fig. 2. (a) and (c) |E|-distributions for the composite structure with (a) εh=2 and ε1=5, (c) εh=5 and ε1=2 illuminated by a TM-polarized wave under normal incidence. The working wavelength is λ=125h. The dashed circles denote the positions of additional tiny inclusions. (b) and (d) Absorptance by the composite with (b) εh=2 and ε1=5, and (d) εh=5 and ε1=2 as functions of the working wavelength based on simulations of the actual composite (dots), traditional EMT (solid lines), and corrected EMT (dashed lines), when an additional tiny inclusion successively moves from position 1 to position 4. The radius of the tiny inclusion is r1/6, and the relative permittivity is 2+i in (b) and 5+i in (d).

Fig. 3. (a) Illustration of a complex composite structure consisting of a host embedded with two cloud-like large inclusions and three tiny inclusions placed at positions 1–3. (b) |E|-distribution illuminated by a TM-polarized wave under normal incidence in the absence of the three tiny inclusions. (c) Absorptance by the composite as a function of the working wavelength based on simulations of the actual composite (dots), traditional EMT (solid lines), and corrected EMT (dashed lines). (d) Transmittance through the effective media based on the traditional EMT (black lines) and the corrected EMT (red lines) by assuming N layers of unit cells along the propagation direction. The working wavelength is λ=125h in (b) and (d). The three tiny inclusions are the same with εa=2+0.5i and ra=0.015w. Other relevant parameters are εh=2, ε1=5, and ε2=1.

Fig. 4. (a) Illustration of a composite structure consisting of a host embedded with ENZ inclusion and two lossy inclusions. (b) |E|-distribution illuminated by a TM-polarized wave under normal incidence in the absence of the lossy inclusions. (c) Absorptance by the composite as functions of the working wavelength based on simulations of the actual composite (dots), traditional EMT (solid lines), and corrected EMT (dashed lines). (d) Transmittance through the effective media based on the traditional EMT (black lines) and the corrected EMT (red lines) by assuming N layers of unit cells along the propagation direction. The working wavelength is λ=125h in (b) and (d). The two tiny inclusions are the same with εa=2+i. Other relevant parameters are εh=2 and ε1=0.001.

Fig. 5. (a) Illustration of a 3D composite structure consisting of a SiO2 host and a Si sphere (radius 15 nm) surrounded by eight tiny ITO spheres (radius 3 nm). (b) |E|-distribution illuminated by a plane wave under normal incidence in the absence of the ITO spheres. (c) Absorptance by the composite as a function of working wavelength based on simulations of the actual composite (dots), traditional EMT (solid lines), and corrected EMT (dashed lines). (d) Transmittance on a log scale [i.e., log(T)], through the effective media based on the traditional EMT (black lines) and the corrected EMT (red lines) by assuming N layers of unit cells along the propagation direction. The working wavelength is 1400 nm in (b) and (d).