414
A. Pors et al.
by minimizing a function β(n, ∂) which describes the error between the experimental and theoretical metamaterial transmission and metamaterial grating diffraction
efficiency, respectively. For a specific wavelength, the error function exhibits distinct minima (Fig. 11.7a) corresponding to solutions of n and ∂, thereby enabling
experimental access to the DED metamaterial wavelength dispersions (Figs. 11.7b
and 11.7c). Comparison of the experimental and simulated real and imaginary parts
of the metamaterial refractive index of the DEDs comprised of two (Fig. 11.7b) and
three (Fig. 11.7c) nanorods reveals reasonably consistent trends regarding the wavelength dispersion of the refractive index. However, there is in general a substantial
difference in the actual value of the real part. Nevertheless, this is not unexpected,
when taking into account the evident differences in resonance strengths and widths
in the experimental and simulated transmission and reflection spectra (Fig. 11.6), and
n
κ
1.6
1.7
1.8
1.9
2
0.1
0.2
0.3
0.4
0.5
0
0.5
1
1.5
2
(b)
(a)
(c)
Fig. 11.7 a Contour plot showing the error β(n, ∂) in the case of a DED metamaterial consisting
of three nanorods at the wavelength 770 nm, which is used for retrieval of n ∼ 1.84 and ∂ ∼ 0.34
corresponding to the minimum in β(n, ∂). b, c Experimental and simulated real (n) and imaginary
(∂) parts of the complex refractive index for the DED metamaterial consisting of b two nanorods and
c three nanorods. In the simulations and experiment, the metamaterial thickness is 150 nm, which
corresponds to 50 nm of gold embedded in 50 nm PMMA above and below the nanorod antennas.
Reproduced with permission from Ref. [34], DOI: 10.1088/2040-8978/13/5/055106. ©Institute of
Physics 2011
A. Pors et al.
by minimizing a function β(n, ∂) which describes the error between the experimental and theoretical metamaterial transmission and metamaterial grating diffraction
efficiency, respectively. For a specific wavelength, the error function exhibits distinct minima (Fig. 11.7a) corresponding to solutions of n and ∂, thereby enabling
experimental access to the DED metamaterial wavelength dispersions (Figs. 11.7b
and 11.7c). Comparison of the experimental and simulated real and imaginary parts
of the metamaterial refractive index of the DEDs comprised of two (Fig. 11.7b) and
three (Fig. 11.7c) nanorods reveals reasonably consistent trends regarding the wavelength dispersion of the refractive index. However, there is in general a substantial
difference in the actual value of the real part. Nevertheless, this is not unexpected,
when taking into account the evident differences in resonance strengths and widths
in the experimental and simulated transmission and reflection spectra (Fig. 11.6), and
n
κ
1.6
1.7
1.8
1.9
2
0.1
0.2
0.3
0.4
0.5
0
0.5
1
1.5
2
(b)
(a)
(c)
Fig. 11.7 a Contour plot showing the error β(n, ∂) in the case of a DED metamaterial consisting
of three nanorods at the wavelength 770 nm, which is used for retrieval of n ∼ 1.84 and ∂ ∼ 0.34
corresponding to the minimum in β(n, ∂). b, c Experimental and simulated real (n) and imaginary
(∂) parts of the complex refractive index for the DED metamaterial consisting of b two nanorods and
c three nanorods. In the simulations and experiment, the metamaterial thickness is 150 nm, which
corresponds to 50 nm of gold embedded in 50 nm PMMA above and below the nanorod antennas.
Reproduced with permission from Ref. [34], DOI: 10.1088/2040-8978/13/5/055106. ©Institute of
Physics 2011