Terahertz Transmission‐Type Metasurface for the Linear and Circular Polarization Wavefront Manipulation

Abstract

A transmission‐type metasurface (MS) based on the combined geometric and transmission phase is proposed and investigated here numerically, which can achieve independently manipulation of the circular polarization (CP) and linear polarization (LP) wavefront at terahertz (THz) region. The unit‐cell of the proposed MS is composed of the dielectric substrate sandwiched with the bilayered inner centrosymmetric‐notched‐elliptic (CNE), outer C‐shaped, and single‐split‐ring (SSR) structures. The proposed MS can convert the normal incident LP wave to its orthogonal one at the lower frequency (f1 = 0.68 THz) after transmission and left‐handed circular polarization to the transmitted right‐handed circular polarization wave or vice versa at the higher frequency (f2 = 1.34 THz). The full 2π phase shifts of the both transmitted LP and CP waves can be realized independently and simultaneously by varying the opening and orientation angles of the outer SSR structure based on the transmission phase and the orientation angle of the inner CNE structure based on geometric phase, respectively. As proofs of concept, anomalous refraction, planar focusing, and vortex beam generation for both LP and CP waves are demonstrated numerically. These findings show great potential applications in imaging and communication systems, providing new possibilities to develop multifunctional THz device for both LP and CP waves.

Photo-Excited Metasurface for Tunable Terahertz Reflective Circular Polarization Conversion and Anomalous Beam Deflection at Two Frequencies Independently

“…Note that the two distinct resonators (Si ESP and CDSR structure) are responsible for manipulating the THz wave at two corresponding frequencies independently. The sequence arrangement of discrete ESP and CDSR structures will inevitably lead to cross-coupling effects, which will cause some discrepancies between the designed phase and the practical arranged phase, thus finally resulting in a reduction of MS device efficiency [ 31 , 32 ]. In our design, the metal CR structure is added and used to reduce the cross-talk and cross-coupling effect between the ESP and CDSR structures.…”

“…Compared to MMs, MSs offer the advantage of being lighter, thinner, and easier to fabricate, while also providing more flexible modulation of THz waves. Thus, various THz devices with single or composite functions, such as abnormal refraction/reflection, perfect absorption, beam splitters, orbital angular momentum, polarization conversion, beam deflection, and so on, have been proposed intensively [ 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 ]. Among these functions, polarization conversion and beam deflection are some of the most fundamental functionalities in photoelectric information processing systems.…”

Design of a Three-channel Frequency Multiplexing Metasurface in Full Space

“…The phase discretization of 2π can be broadened from 1-bit to multi-bits [8,9], further simplifying the design and manufacturing of metasurface devices. Despite the limited number of encoded states, coded metasurfaces are usable to effectuate applications such as anomalous deflection [10], radar cross section (RCS) reduction [11,12], and vortex wave generation [13,14].…”

Spin-decoupled excitation and wavefront shaping of structured surface waves via on-chip terahertz metasurfaces

“…Recently, metasurfaces, which are ultrathin planar structures composed of subwavelength meta-atoms, have shown great potential to steer EM waves. By carefully designing the shapes and sizes of meta-atoms, plenty of EM wave manipulating applications have been achieved, including modulators, 9,10 holography, 11,12 polarization control, 13,14,28 vectorial fields, 15,16 wavefront manipulation, 17,18,[38][39][40][41] edge detection, [30][31][32] and topological photonics. [21][22][23][34][35][36] However, to date plentiful metasurfaces concentrate on the manipulation of PWs, while the manipulation of SWs through metasurfaces is not common.…”