Microwave Vortex Transceiver System with Continuous Tunability Using Identical Plasmonic Resonators

Abstract

features. Since then, there are long-time confusion about the phase vortex and the OAM, although these two concepts are not necessarily linked. [3] The fancy properties of optical vortices provide new understandings for a broad range of physical phenomena, [4][5][6][7][8][9] including light-matter interactions, [10,11] spin-orbit coupling, [12] Bose-Einstein condensates, [13] etc. Meanwhile, promising applications based on optical vortices have been developed in optical manipulations, [14] chiral molecular sensing, [10,15] high-capacity optical communications, [16] etc.The concepts and investigations of optical vortices have been generalized to microwave frequencies since 2007. [17] It has been demonstrated that multiplexing microwave vortices of different orders can increase the communication capacity without increasing the bandwidth. [18] Vortex beams can also acquire the azimuth information of the radar target, therefore benefiting the novel information-rich radar for target recognition. [19] Recently, novel principles and inspiring applications of microwave vortices keep emerging, such as chirality detection, [20] spinning speed detection, [21,22] etc.Compared with the optical vortices, it is more convenient to manipulate the microwave phase distributions in a subwavelength scale for vortex generation. Spiral phase plates and helicoidal parabolic antennas are traditionally employed. [18,23] Metasurfaces are also eye-catching in the microwave band since the flexible artificial unit design brings excellent phase modulation capabilities. [24][25][26] Recently, spoof localized surface plasmons (SLSPs) cut a good figure. [20,[27][28][29][30][31] SLSPs are printed on planar circuit boards and can generate microwave vortices using single resonators, hence highlighting their outstanding integration and convenience. Compared with other vortex generations based on single-resonators (e.g., patch antennas [32] and dielectric resonators [33] ), SLSPs present superiorities such as strong modal confinements, high quality-factors, and flexible symmetry engineering capabilities based on the plasmonic metamaterial concepts. [34][35][36][37] In contrast to the flourishment of vortex generation techniques, the detection and analysis of vortex modes remain challenging, which relies on the measurement of the phase gradient in a plane perpendicular to the beam axis. [38][39][40] Based on the collected phase distributions, mode purities, and orbital angular momentum spectra can be calculated to analyze the target vortex modes, [41][42][43] which can be generalized to vortex modes of fractional orders. [25] Such phase detection techniques Electromagnetic vortices have attracted vast interest for their unique physics and promising applications. Tremendous efforts have been devoted to vortex generations, but receiving vortex modes remains challenging and commonly requires spatial phase gradient measurements. Here, a compact microwave vortex transceiver system based on reversible superposition and decomposition of degenerate and orthogo...

Exceptional Point in a Microwave Plasmonic Dipole Resonator for Sub‐Microliter Solution Sensing

“…[44,45] For the symmetric SLSP resonator, the two dipoles share a degenerate eigenfrequency around 2.614 GHz, while the simulated values present very slight differences. [46,47] For the implementation of the EP state in a microstrip circuit, the chiral SLSP is excited by a side-coupled microstrip line. As shown in the inset of Figure 3a, the microstrip line width is W 1 = 1.32 mm therefore its impedance is 50 Ω.…”

“…In the contrastive symmetric SLSP structure, two degenerate and orthogonal dipoles are excited by the side-coupled microstrip line simultaneously and superposed to form the first-order vortex mode. [47] Although the EP and DP states present similar vortex fields, they are originated from different resonance principles and perform discriminative sensitivities. [49]…”

Impacts of Liquid Level on Microwave Resonance Sensing with a Flexible Microfluidic Channel

“…[1,30,[32][33][34] The features of deepsubwavelength confinement, excellent Q-factors, and high local sensitivity make SLSPs competitive candidates for trace-amount biomedical sensing. [8,9,22,28,[35][36][37][38][39] In 2022, Zhang and Cui reported sub-micromole glucose sensing using an SLSP resonator with an electrical size smaller than 1/40 wavelength and a high Q-factor of 187. [8] With the continuous promotion of sensitivities and detection limits, these sensors can also respond to the environmental distractions sensitively.…”

On-demand multiplexed vortex beams for terahertz polarization detection based on metasurfaces

“…[27][28][29] The vortex beam determined by the spatial spiral phase wavefront structure can carry the orbital angular momentum (OAM), and the spiral phase profile can be described as exp(ilθ), which carries OAM of lħ per photon. 30 The parameters l and θ denote the topological charge and the azimuth angle, respectively. Besides, the superposition of vortex beams plays an important role in many cutting-edge optical applications due to the rich polarization properties.…”