Pixelated metasurfaces for linear-polarization conversion and absorption

Abstract

Terahertz metasurfaces with pixelated meta-atoms were designed for linearpolarization conversion and absorption. The differences between the two functionalities emerged from the number and arrangement of metal-dielectric combos patching some but not necessarily every pixel of each meta-atom. A patching arrangement for a meta-atom with 3×3 pixels yielded polarization conversion ratio (PCR) > 0.9 over the 10.20-16.08 THz band, whereas another yielded absorptance (A) > 0.9 over the 27.67-28.73 THz band. A third patching arrangement delivered both functionalities, albeit in different spectral regimes: high PCR and high A at 13.92 THz and 29.1 THz, respectively. The spatial profiles of the electric and magnetic fields in each meta-atom suffice to explain the display of these functionalities. The generality of the pixelated meta-atom approach was supported by a meta-atom with 4×4 pixels.

Triple‐band metasurface absorber for RF energy harvesting applications

“…Here, the free space wavenumber is denoted with $${k}_{{\rm{o}}}(=2\pi /{\lambda }_{0})$$, and $${\lambda }_{0}$$ is the free‐space wavelength. The phasor form of the reflected electric field can be written as a doubly infinite series of Floquet harmonics owing to periodicity along the $$x$$‐ and $$y$$‐axis 8 : $$$\begin{array}{c}{E}_{{\rm{r}}}=\sum _{m}\sum _{n}\left\{\left[\left({<mpadded xmlns="http://www.w3.org/1998/Math/MathML">R</mpadded>}_{xx}^{m,n}{E}_{x}+{<mpadded xmlns="http://www.w3.org/1998/Math/MathML">R</mpadded>}_{xy}^{m,n}{E}_{y}\right){\hat{{\rm{u}}}}_{{\rm{x}}}+\left({<mpadded xmlns="http://www.w3.org/1998/Math/MathML">R</mpadded>}_{yx}^{m,n}{E}_{x}\right.\right.\right.\,\\ \,+\,\left.\left.\left. {<mpadded xmlns="http://www.w3.org/1998/Math/MathML">R</mpadded>}_{yy}^{m,n}{E}_{y}\right){\hat{{\rm{u}}}}_{{\rm{y}}}\right]\,\left.\text{exp}\left[\displaystyle \frac{j(mx+ny)2\pi }{L}\right]\text{exp}(-j{\beta }^{m,n}z)\right\},\end{array}$$$where the wavenumbers …”

“…A metasurface contains a periodic arrangement of the meta‐atoms along two mutually perpendicular directions maintaining sub‐wavelength periodicity. These meta‐atoms act as resonators and can be designed by using various methods like the pixelated concept, split‐ring resonators (SRRs), crosses, and so on 8–10 . The metasurface with various designs of meta‐atoms has been used for polarization conversion, absorbers, antennas, and filters 10–13 .…”

“…These meta-atoms act as resonators and can be designed by using various methods like the pixelated concept, split-ring resonators (SRRs), crosses, and so on. [8][9][10] The metasurface with various designs of metaatoms has been used for polarization conversion, absorbers, antennas, and filters. [10][11][12][13] A metasurface absorber can also be used for sensing the environment.…”

Polarization-insensitive graphene-based THz rasorber with ATA characteristics

“…The polyimide substrate layer is used for providing insulation and passivation in the fabrication of THz devices. These two layers are separated by a spacer made of a [31]. The top layer has a modified swastika geometry metallization, loaded with graphene strips to provide dual-band absorption, providing a band-stop response in the desired operating band.…”

Topological optimization of electrically tunable silicon-organic metasurfaces

“…6,7 Metasurface-based device designs usually depend on analytical studies that utilize either a mathematical model or information extracted from the literature. This information often includes the structural dimensions and shape parameters of simple patterns (such as U's, 8 ellipses, 9 and pixel arrays 5,10 ). Even for these designs, there are studies wherein optimization algorithms have been integrated in the device design process, thereby creating an alternative approach which leads to non-intuitive geometries through topological optimization.…”