Localized plasmon resonance of a metal nanoantenna is determined by its size, shape and environment. Here, we diminish the size dependence by using multilayer metamaterials as epsilon-near-zero (ENZ) substrates. By means of the vanishing index of the substrate, we show that the spectral position of the plasmonic resonance becomes less sensitive to the characteristics of the plasmonic nanostructure and is controlled mostly by the substrate, and hence, it is pinned at a fixed narrow spectral range near the ENZ wavelength. Moreover, this plasmon wavelength can be adjusted by tuning the ENZ region of the substrate, for the same size nanodisk (ND) array. We also show that the difference in the phase of the scattered field by different size NDs at a certain distance is reduced when the substrate is changed to ENZ metamaterial. This provides effective control of the phase contribution of each nanostructure. Our results could be utilized to manipulate the resonance for advanced metasurfaces and plasmonic applications, especially when precise control of the plasmon resonance is required in flat optics designs. In addition, the pinning wavelength can be tuned optically, electrically and thermally by introducing active layers inside the hyperbolic metamaterial.
We propose and demonstrate the fabrication of a curved fishnet metamaterial integrated into a rolled-up tube (RUT) that consists of eight alternating layers of gold and silicon dioxide. We adopt a self-rolled technique for the fabrication of metal/dielectric microtubes with large enough diameters for optical characterization. We experimentally characterize the fabricated fishnet structure, and by means of numerical calculations, we show that the fabricated structure possesses a negative refractive index with a high figure of merit. We demonstrate that the negative refractive index region can be tuned by precisely controlling the dimensions of the holes forming the metamaterial. The results of this study open up the possibility to obtain a simple, fast, and flexible platform for the fabrication of RUT-based metamaterials for bioimaging and sensing applications.
Planar metasurfaces
provide exceptional wavefront manipulation
at the subwavelength scale by controlling the phase of the light.
Here, we introduce an out-of-plane nanohole-based metasurface design
with the implementation of a unique self-rolling technique. The photoresist-based
technique enables the fabrication of the metasurface formed by nanohole
arrays on gold (Au) and silicon dioxide (SiO
2
) rolled-up
microtubes. The curved nature of the tube allows the fabrication of
an out-of-plane metasurface that can effectively control the wavefront
compared to the common planar counterparts. This effect is verified
by the spectral measurements of the fabricated samples. In addition,
we analytically calculated the dispersion relation to identify the
resonance wavelength of the structure and numerically calculate the
phase of the transmitted light through the holes with different sizes.
Our work forms the basis for the unique platform to introduce a new
feature to the metasurfaces, which may find many applications from
stacked metasurface layers to optical trapping particles inside the
tube.
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