Terahertz dual phase gradient metasurfaces: high-efficiency binary-channel spoof surface plasmon excitation

Abstract

Spoof surface plasmon meta-couplers are compact antennas which link propagating waves and surface waves. However, most of them are designed with a fixed phase gradient and channel for the incident waves with specific polarization, which limits their further applications in multichannel scenarios. In this Letter, we propose, to the best of our knowledge, a new method that combines the Brillouin folds theory with the Generalized Snell Law. We demonstrate that when the phase gradient of the metasurface is large enough, Brillouin folds effect will occur, which will create dual phase gradient space in a single metasurface. With this method, we design two novel terahertz meta-couplers with functionalities of symmetrical and asymmetrical binary-channel/bidirectional SSP excitation. Furthermore, finite element method (FEM) simulations are performed to demonstrate their functionalities. Considering the orthogonality of the incident waves, there can be a total of four independent space channels to excite SSP on one metasurface. This work may open up new routes in multi-channel SSP meta-couplers and multi-beam surface wave antennas.

Robust Effective‐Medium Characteristics of Bianisotropic Reflective Metasurfaces based on Field‐Circuit Combined Analysis

“…Equation (11) indicates that the incident angles determine the relationship between r 1 and r 2 . Since only S 11 parameters can be obtained in the simulation or measurement, it is necessary to present the formulas between S 11 and r 1 or r 2 .…”

“…Then, the valid range of the 2 can be confirmed by checking in which range the retrieved results match well with each other. Before solving the equation set (11), (14), and 17, one can first obtain another relation of r 1 and r 2 using Equation 14and 17e −2jn eff k 0…”

“…Metasurfaces have been powerful tools to manipulate electromagnetic (EM) waves with various frequencies by arbitrarily tailoring amplitude and phase on the subwavelength scale. [1] With characteristics of ultrathin thickness, low loss, and easy fabrication, metasurfaces possess advantages over 3D metamaterials in practical applications, e.g., focusing or superfocusing, [2][3][4][5][6][7] spoof surface plasmon polariton couplers, [8][9][10][11][12][13] multichannel DOI: 10.1002/adts.202000246 reflectors, [14,15] etc. If the unit cells in metasurfaces are fully characterized, EM wave propagation, reflection, and transmission properties of metasurfaces can be tailored and accurately be predicted.…”

Surface Electromagnetic Performance Analysis of a Graphene-Based Terahertz Sensor Using a Novel Spectroscopy Technique

“…Contrary to the optical frequencies, surface plasmons cannot originally exist in metals at THz frequencies however, graphene can support surface plasmon oscillations at THz frequencies. [35], [36]. A considerable amount of research shows that there are two types of outer electrons ( and ) in the molecular structure of graphene and both can support plasmons.…”

Generalized Wavefront Manipulation: Dual-Foci Superfocusing with Hybrid-Magnitude Evanescent Modes and Terahertz Space-Division Multiplexing

“…With the development of electromagnetism, especially the proposal of metamaterials and metasurfaces, more and more flexibility and feasibility are accessible to control the propagation of EM waves on the subwavelength scales. Numerous methods and theories are proposed to design devices and arbitrarily steer light, for example, generalized laws of refraction and reflection, − spoof surface plasmon polarizations, − Fano resonance, − wave-vector matching, ,,− gradient index materials, ,,, and retrieval of constitutive effective parameters. − Each method is used to propose corresponding specific functions, and a considerable part of them are aimed at the far field. Simultaneously, the near-field applications of the subwavelength structures and the methods to flexibly manipulate EM waves intrigue more and more researchers and engineers.…”