Nearly total absorption of light and heat generation by plasmonic metamaterials

We theoretically and numerically study the absorption effect and the heat generation in plasmonic metamaterials under light radiation at their plasmonic resonance. Three different types of structures, all possessing high-performance absorption for visible lights, are investigated. The main aim of this work is to present an intuitive and original understanding of the high-performance absorption effects. From the macroscopic electromagnetic point of view, the effective-medium approach is used to describe the absorption effects of the plasmonic metamaterials. On the other hand, the field distributions and heat generation effects in such plasmonic nanostructures are investigated, which also provides a satisfactory qualitative description of such absorption behavior based upon the microscopic perspective.

Figure 1

Geometry of the structures studied in this paper. The orange regions are silver, and the cyan region is the dielectric. $W_x$ and $W_y$ represent, respectively, the side lengths of the rectangular metallic particle along the $x$ and $y$ axis and $t$ represents its thickness. $d$ and h, respectively, denote the thicknesses of the dielectric layer and the silver film. $a$ is the lattice constant.

Figure 2

(a) The simulated reflection ($R$), transmission ($T$) spectra, (b) correspondingly calculated absorbance ($A$) and attenuation ($Q$${}_{\mathrm{att}}$) spectra, and (c) the sum of higher-order scattering ($S$) spectrum for the first kind of metamaterial absorbers.

Figure 3

Absorbance as a function of wavelength and the angle of incidence for the first kind of metamaterial absorber. (a) TM polarization; (b) TE polarization.

Figure 4

(a) Magnitude and (b) phase of the simulated $S$ parameters for the first kind of metamaterial absorber. Retrieved permittivity (c), permeability (d), refractive index (e), and impedance (f) are also shown.

Figure 5

Absorbance as a function of wavelength and the width of the silver particles, where Wx $=$ Wy $=$ W, $t$ $=$ 30 nm, $d$ $=$ 12 nm, $h$ $=$ 80 nm, and $a$ $=$ 250 nm.

Figure 6

The simulated reflectance, transmittance, and the corresponding calculated absorbance as functions of wavelength and the thickness of silver film $h$ with other parameters $W$ $=$ 170 nm, $t$ $=$ 30 nm, $d$ $=$ 12 nm, and $a$ $=$ 250 nm.

Figure 7

(a) The maximum absorption and correspondingly simulated reflection, with transmission spectra for mode (2) as functions of $d$ with $W$ $=$ 170 nm, $t$ $=$ 30 nm, $h$ $=$ 80 nm, and $a$ $=$ 250 nm.(b) The resonant absorption peak wavelength λ${}_R$ corresponding to (a) as a function of $d$. (c) The maximum absorption ($A$) and correspondingly simulated reflection ($R$), transmission ($T$) spectra for mode (0) as functions of $d$ with $W$ $=$ 170 nm, $t$ $=$ 30 nm, $h$ $=$ 80 nm, and $a$ $=$ 250 nm. (d) The resonant absorption peak wavelength λ${}_R$ corresponding to (c) as a function of $d$.

Figure 8

(a) The maximum absorption ($A$) and correspondingly simulated reflection ($R$) and transmission ($T$) spectra for mode (2) as functions of the thickness of silver particles $t$ with $W$ $=$ 170 nm, $d$ $=$ 12 nm, $h$ $=$ 80 nm, and $a$ $=$ 250 nm. (b) The resonant absorption peak wavelength λ${}_R$ corresponding to (a) as a function of $t$. (c) The maximum absorption ($A$) and correspondingly simulated reflection ($R$) and transmission ($T$) spectra for mode (0) as functions of the thickness of silver particles $t$ with other geometric parameters $W$ $=$ 170 nm, $d$ $=$ 12 nm, $h$ $=$ 80 nm, and $a$ $=$ 250 nm. (d) The resonant absorption peak wavelength λ${}_R$ corresponding to (c) as a function of $t$.

Figure 9

Dependence of the absorption effect on the refractive index of the dielectric layer $n$${}_d$. (a) Mode (2); (b) the resonant absorption peak wavelength λ${}_R$ corresponding to (a); (c) Mode (0); (d) the resonant absorption peak wavelength λ${}_R$ corresponding to (c).

Figure 10

Absorbance as a function of wavelength and the angle of incidence for the second kind of metamaterial absorber: (a) TM polarization; (b) TE polarization.

Figure 11

Field distributions and resistive heat for the three modes. (a)–(c) Mode (0) at resonant wavelength 1.48 μm for the normal incident angle. (d)–(f) Mode (1) at resonant wavelength 787 nm for the incident angle of 45°. (g)–(i) Mode (2) at resonant wavelength 583 nm for the normal incident angle. In the field maps of (a), (d), and (g), the arrows represent electric displacement and the color represents the magnitude of the magnetic field. For (b), (e), and (h), the arrows represent the direction of electric field, and the color denotes the magnitude of the electric field. Panels (c), (f), and (i) depict resistive heat corresponding to each case.

Figure 12

Retrieved effective parameters, (a) permittivity and (b) permeability, for the second kind of metamaterial absorber as functions of wavelength. Optical parameters, (c) permittivity and (d) permeability, calculated with formula (12) as functions of wavelength.

Figure 13

(a) The simulated reflection ($R$) and transmission ($T$) spectra, (b) correspondingly calculated absorbance ($A$) and attenuation ($Q$${}_{\mathrm{att}}$) spectra, and (c) the sum of higher-order scattering ($S$) spectrum for the third kind of metamaterial absorbers.

Figure 14

Attenuation as a function of wavelength and the angle of incidence for the third kind of metamaterial absorbers. (a) TM polarization; (b) TE polarization.

Figure 15

Electric (E) and magnetic (H) field distributions and resistive heat ($q$) for the three modes: (a)–(c) at wavelength 595 nm for the normal incident angle; (d)–(f) at wavelength 691 nm for the incident angle of 60°; (g)–(i) at wavelength 555 nm for the incident angle of 60°.