Millimeter-wave (mmWave) communication technologies offer abundant spectrum resources and higher data rates that present new opportunities to facilitate fifth-generation (5G) Internet of Things (IoT) systems. As IoT devices are randomly distributed in the environment, mmWave antennas with multiple switched directional beams are a better choice to reduce data collisions. In this context, a wideband multibeam antenna with a compact structure is presented for various mmWave IoT applications. First, a wideband dual-polarized magnetoelectric dipole (ME-dipole) antenna is developed as the excitation for the quasi-spherical lens. Next, by incorporating the lens with a group of the source antennas positioned at each edge of a hexagonal ground plane, six tilted beams with dual polarization are generated for pattern and polarization diversities. A prototype is constructed and measured, demonstrating a measured bandwidth from 27 to 37 GHz. Moreover, the maximum measured gain for each beam is around 18 dBi. Benefiting from the advantages of wideband operation and excellent radiation performance, the proposed mmWave-powered multibeam antenna can be mounted on the ceiling to communicate with multiple users and smart devices beneath it, offering a reliable and cost-effective solution for 5G IoT.

A wideband dual-circularly polarized (dual-CP) magneto-electric dipole reflectarray with independent beam control is reported. A dual-CP phase shifting unit cell is proposed to provide independent phase manipulation on the two CP waves. For proof, a 2 x 2 bit reflectarray operating at X-band with 16 x 16 elements is developed with different beam directions. The results show that the peak gain of the prototype is up to 23.85 dBic at 10.5GHzwith an aperture efficiency of 30.2%. The joint bandwidth for the 3 dB AR and 3 dB gain is around 22.5% (9.25-11.5 GHz). With advantages of wide operating bandwidth and independent beam control, the proposed dual-CP reflectarray would be an attractive candidate for satellite communication.

Stimuli-responsive patterned photonic actuators, characterized by their patterned nano/microscale structures and capacity to demonstrate synergistic color changes and shape morphing in response to external stimuli, have attracted intense scientific attention. However, traditional patterned photonic actuator systems still face limitations such as cumbersome and time-consuming preparation processes and small-scale deformations. Herein, we introduce a facile approach involving an athermal embossing technique to rapidly fabricate patterned photonic actuators based on near-infrared (NIR) light-responsive liquid crystal elastomers. The resulting patterned photonic actuators demonstrate remarkable features, including brilliant angle-dependent structural color, complex three-dimensional actuation, and good color durability under NIR light stimulation. As illustrative demonstrations of the proof-of-concept, we fabricate two light-fuelled patterned photonic soft actuators: a butterfly-inspired actuator that can produce wing-flapping dynamic changes in structural color, and an origami crane-shaped actuator with shape memory, structural color information storage, and dynamic display properties. This strategy provides distinct insights into the design and fabrication of various patterned photonic soft robotic devices and intelligent actuators.

A design method of a two-channel multiplexing transmissive Linear-to-Circular polarization converter (PC) with independent controllability is reported in this paper. In order to verify the feasibility of the design concept, sixteen kinds of anisotropic converter unit cells with linear polarization (LP) receiving and circular polarization (CP) transmitting are proposed. The Linear-to-Circular PC is enabled by introducing a length difference of.g/4 between the two parts of microstrip lines of the unit cell, which makes the transmission phase difference between the plane wave of transverse electric mode and transverse magnetic mode is 90 degrees. Based on the hybrid phase compensation strategy of propagation phase (PP) and geometric phase (GP), 16 kinds of cells are creatively designed, and the proposed idea is verified by forming an array. The simulation results show that the peak gain of dual CP beam is greater than 25.3 dBic, and the overlapping bandwidth of 3-dB axial ratio (AR) and 3-dB gain bandwidth is greater than 20%. The proposed transmissive Linear-to-Circular PC has the advantages of two-channel multiplexing and independent beam control, and is expected to play an important role in wireless and satellite systems.

A circularly polarized (CP) reconfigurable and linear polarized (LP) orbital angular momentum (OAM) mode multiplexing concentric uniform circular array (CUCA) is presented. The designed antenna array consists of two parts: an inner UCA composed of four LP antenna elements and an external UCA composed of eight sequentially rotated CP reconfigurable elements. The inner UCA and outer UCA are capable of generating multiplexed OAM beams at 3.28 GHz with l = +1 and mode l = ±2, respectively. To assess the performance of these vortex beams, a purity analysis of the multiplexed OAM modes was conducted. When all elements are fed with the same amplitude signal, the mode purity of the inner UCA at l = +1 with LP is 27.6%. As for the external UCA, at l = +2 with right-hand CP (RHCP), the mode purity in the electric field Ex- component is 32.5%, and in the Ey- component, it is 47.5%. Furthermore, l = -2 with left-hand CP (LHCP) has similar results. The obtained results are consistent, validating the potential application of the proposed modal multiplexing method in future communication.

In this article, the design and proof-of-concept demonstration of a dual-channel linearly polarized (LP) to circularly polarized (CP) conversion transmitarray are reported, which possesses the capability of independent beamforming for each channel. The fixed receiving patch and rotatable transmitting patch of the employed unit cell are connected by introducing two orthogonal signal paths with a phase difference of 90(degrees). Hence, the dual orthogonal LP incident waves from feeds can be effectively converted to dual CP radiation, therefore creating two independent LP-to-CP conversion channels. Moreover, based on a hybrid compensation strategy of propagation and geometric phase, the unit cell can provide independent phase control for the two channels through the cooperative control of the length of the two signal paths and the rotation angle of the transmitting patch. To demonstrate the proposed methodology, a 2 x 2 bit dual CP transmitarray with a designed dual LP horn feed, featuring different beam directions, is developed by utilizing the independent dual-channel phase shifting unit cell. A prototype of the integrated transmitarray is fabricated and characterized, exhibiting a good agreement between the simulation and the measurement. The measured gain at the center frequency of 20 GHz for the two channels is 23.6 and 23.1 dBic, and the joint bandwidth of 3-dB axial ratio (AR) and 3-dB gain bandwidth is wider than 20%. With advantages of independent controllability, good CP performance, and stable radiation pattern, the proposed wideband dual-channel CP transmitarray would be an attractive candidate for wireless and satellite communication systems.

In this paper, the design and implementation of a wideband circularly polarized (CP) reflectarray which consists of magneto-electric (ME) dipole elements at X-band are reported. The cell uses the ME dipole to achieve broadband characteristic. Beam independent controllability is realized through the cooperation of dynamic phase and Berry phase. The dynamic phase can be regulated via length modulation of microstrip lines while the Berry phase can be manipulated by rotating the element. The simulation results show that LHCP reflection wave at θ = 10° and RHCP reflection wave at θ = -20° at 10.5 GHz are created by the reflectarray. Moreover, the maximum gain value of dual CP wave can both reach 24.6 dBic at 10.5 GHz while the 3 dB axial ratio (AR) covers a frequency band from 8.5 to 12 GHz, respectively. With the advantages of broadband, high gain and independently controllable wave beams, the proposed wideband CP reflectarray would have appealing application prospects in satellite communications.

Graphene plasmonic logic gates (GPLGs) with high compaction and simple structure are presented and investigated in this paper. Due to the strong confinement of edge mode graphene surface plasmon polaritons (EGSPPs), it can process optical signal on nanoscale ribbons with both straight and flexible shapes. Three eigen modes of graphene surface plasmon polaritons (GSPPs) are studied from the aspect of their propagation properties, indicating that the symmetric edge-mode (SEM) is an optimal choice for designing the GPLGs. Finally, some basic logic gates, i.e., the XOR and XNOR gates, are demonstrated by employing the SEM. More kind of GPLGs and functional devices are expected to be realized by cascading these basic logic gates.

Plasmons induced by topological insulator (TI) Bi2Se3 micro-ribbon arrays have been experimentally observed recently (Nature nanotechnology 2013, 8, 556-560). In this letter, the surface plasmons excited by TI Bi2Se3 micro-disk arrays are investigated by the methods of full-wave numerical simulations. Numerical simulation results show that thin Bi2Se3 micro-disk arrays can support dipolar plasmon resonances in the terahertz (THz) regimes and the absorptions can be tuned by the structure parameters. In addition to the plasmon mode, two phonon-mode responses are also observed, which confirms the experimental results of micro-ribbon arrays. Our work further proves that TI can be a good candidate of plasmonic platform.

A three-dimensional plasmonic open waveguide ring resonator (WRR) based on graphene nanoribbons, which has high confinement and multiple tunability, is proposed and numerically investigated. The intensity of edge graphene plasmons modes (EGSPs) in a nanoring resonator reaches the maximum at resonant frequencies, which indicates that EGSPs can efficiently propagate along the open graphene nanoring resonator even though in nanoscale. Furthermore, the resonant frequencies can be easily manipulated not only by adjusting the geometric parameters but also by changing the doping level of graphene via chemical doping or electrostatic gating without changing the physical size of the geometric structure. The proposed plasmonic WRR can find important potential applications in optoelectronic integrated circuits.

The intrinsic strong confinement of flexible graphene plasmons (FGPs) is investigated in this paper, such unique property is interpreted by the ultra small thickness and metal like effective dielectric constant from the perspective of classical electromagnetic analysis. Utilizing this advantage, signals and energy can naturally propagate along curved surfaces with little curve-induced radiation loss and acceptable intrinsic propagation loss. Meanwhile, the metal plasmons (MPs) and graphene plasmons (GPs) on curved waveguides are simulated to illustrate the different property. At last, a stereo resonator is proposed as an application for the FGPs based devices.