Dual-Band High Efficiency Terahertz Meta-Devices Based on Reflective Geometric Metasurfaces

Abstract

The wavelength-dependent behavior of the metasurface is one of the severe disadvantages in the metasurface-based applications, which greatly limits its applications. In this work, a novel reflective building block (unit cell) has been proposed to work at two arbitrary terahertz frequency bands with independent phase control at each band. The geometric phase building block can reflect the incident circularly polarized wave and convert it to the wave with opposite helicity and high conversion efficiencies at both bands. As proof of concept demonstrations, a dual-band cylindrical meta-lens and two vortex beam generators operating at 0.45 and 0.7 THz are investigated to verify the performance of the proposed building block. The simulated results of the metalens agree very well with the theoretical calculations, which are consistent with the design goals. Moreover, the designed vortex metasurfaces reveal a convenient and low-cost way to realize the vortex beam carrying different/same orbital angular momentum modes at two bands.INDEX TERMS Dual-band, independent phase control, high efficiency, reflection.

Multifunctional Metasurface Design with a Generative Adversarial Network

“…Recently, metasurfaces consisting of all-dielectric meta-atoms have drawn enormous attention, [4,7,8] due to their unique capability of supporting EM multipole resonances and significantly lower losses as compared to their metallic counterparts. [9][10][11][12] The multipole responses in a meta-atom can be highly complicated, even for simple shapes, and thus an arbitrary meta-atom's response to an incident EM wave is difficult to predict. Traditional design approach relies on empirical reasoning or trial-and-error, [4,8] which is inefficient and often ineffective, since this approach involves tremendous numerical full-wave simulations (e.g., finite-element method, finite-difference time-domain method, and finite integration technique), which provide accurate predictions but are extremely time consuming.…”

Multifunctional Geometric Metasurfaces Based on Tri‐Spectral Meta‐Atoms with Completely Independent Phase Modulations at Three Wavelengths

“…Therefore, considerable efforts have been focused on demonstration of multiwavelength metadevices that could achieve multiple frequency-dependent functionalities due to the independent phase manipulations. Among these demonstrations, researchers usually adopt shared-aperture technique or spatial multiplexing to design the multiwavelength metadevices in a single layer or a few layers, [21][22][23][24][25][26][27][28][29][30] which could lead to low efficiency due to the reduced number of the active resonators or increased fabrication complexities. In addition, most of the reported multiwavelength metadevices only work at two wavelengths due to the strong coupling effect for closely spaced resonators.…”

Recent progress on RF orbital angular momentum antennas

“…The multiple and tunable features in real-time are the inevitable trend in RF OAM metasurface antenna designs [104]. It is easy for a single metasurface to generate multiple OAM modes by using the superposition of the aperture field or other methods [105][106][107][108][109]. As depicted in Figure 13(a), dual-modes with different radiation directions were obtained by a single metasurface [110].…”