The maximum field enhancements E s-max outside the Au shell of the Au-silica-Au multilayer nanoshells (black dots) and NSNE (red dots) at different resonant wavelengths of ( {left|{omega}_rightrangle}_1 ) modes.
In Figure 6, the maximum field enhancements E s-max outside the Au shell of the Au-silica-Au multilayer nanoshells and NSNE at different resonant wavelengths of ( {left|{omega}_rightrangle}_1 ) modes are compared.
In the inset of Figure 6, the dependences of the resonant wavelength of ( {left|{omega}_rightrangle}_1 ) modes on the Au core radius r 1 are shown for the Au-silica-Au nanoshells and NSNE. Figure 6 Maximum field enhancements E s-max.
Besides, a maximum electric field enhancement reaching 41.8 is also observed in this work.
The maximum electric field enhancement is more than 7 times larger than the initial incident light electric field.
At the same time, this metasurface can achieve near-perfect absorption above 99.9% and maximum electric field enhancement reaching 108 simultaneously, and the strong electric enhancement is confined within a circular area with a diameter of only 3 nm, which is very beneficial to single molecule detection for many surface-enhanced spectroscopies.
Of the achieved nanoparticles such far, low-dimensional (LD) silver nanostructures (e.g., plates, discs, rods, and wires) have been extensively investigated because of an extreme degree of anisotropic geometry together with corners and/or edges (or ends) for generating maximum electromagnetic field enhancement.
Figure 6c shows that the maximum electric field enhancement at the resonant wavelength can reach as high as 108, around 1.4 times compared to the only film-coupled metasurface shown in Fig. 5d, which is much higher than those of the previously reported nanoantennas [21, 60 65].
We found the optimal thicknesses of the layers, which provide the maximum of the field enhancement [14] in the last dielectric layer.
