Dual-Functional Terahertz Waveplate Based on All-Dielectric Metamaterial

Abstract

Terahertz technology has attracted wide attention because of its potential applications in diverse fields, such as spectroscopy, imaging, and nondestructive evaluation, but the lack of functional devices, including polarization convertors, is still a major hurdle for these applications. In previous studies on metamaterialbased polarization convertors, only one single polarization conversion is generally achieved. This paper presents a transmissive dual-functional terahertz waveplate based on an all-dielectric metamaterial composed of periodic subwavelength pillars made of pure silicon that can achieve two different polarization conversions (i.e., a combination of quarter-and half-waveplates) at the same operation frequency and for x-and y-polarized incidences, respectively. Theoretical and numerical analyses are provided to illustrate the design principle. A sample is fabricated and characterized, and the experimental results show that the two polarization conversions are obtained at 1.01 THz, which is in good agreement with the corresponding simulations. Such a dual-functional terahertz waveplate will find applications in terahertz systems and the design strategy can be extended to other frequency ranges as well.

Dual‐Functional Optical Waveplates Based on Gap‐Surface Plasmon Metasurfaces

“…It is straightforward to show that a unit cell composed of a single subwavelength element is not able to achieve the dual‐functional polarization conversion due to insufficient degrees of design freedom. [ 46 ] In our configuration, the rectangular GSP meta‐molecule consists of two rectangular gold (Au) meta‐atoms with different dimensions and orientations sitting on top of a silicon dioxide (SiO 2 ) spacer layer and a continuous bottom Au layer (Figure 1b). Each meta‐atom supports two GSP resonances excited by orthogonal polarizations and associated with the resonant formation of standing‐wave patterns (in two orthogonal directions) for two counterpropagating GSP modes.…”

Terahertz Metasurfaces: Toward Multifunctional and Programmable Wave Manipulation

“…Although the significant feature of the passive metasurface is its fixed structure, functional multiplexing can still be achieved. Multifunctional passive metasurfaces can be divided into frequency multiplexing metasurfaces [31,32] and polarization multiplexing metasurfaces [33][34][35][36][37][38].…”

“…Furthermore, there are many circumstances belonging to polarization multiplexing. To our knowledge, two principles are commonly employed to design polarization multiplexed metasurfaces, one is Pancharatnam-Berry (PB) phase [33][34][35][36][37] and the other is anisotropy [38]. PB phase can be realized by rotating metasurface unit cell structures, such as the C-shaped structure and rod-shaped structure aforementioned, and there exist a specific relationship between the orientation angle and the PB phase.…”

“…Using the multifunctional metasurface, four characters "C, " "F, " "T, " and "W" were chosen to be displayed here, and measured results are shown in Figures 6B-E. Furthermore, the idea of polarization multiplexing has been utilized in designing many other powerful meta-devices, such as dual-functional polarization rotator [33] and dual-functional beam generator [37]. Apart from PB phase, anisotropy is also an effective principle for polarization multiplexing design.…”

None sharp corner localized surface plasmons resonance based ultrathin metasurface single layer quarter wave plate

“…Recently, as the very fast development of metasurface structures, localized surface plasmons (LSP) resonance based wave plates have been widely researched and published 1 – 19 . Some other metasurface wave plates such as dielectric metasurface wave plates are also studied 20 , 21 . The rapid development of nanostructures provides a new way of designing metasurface devices 22 – 28 .…”