Tunable multifunctional terahertz metasurface based on an indium antimonide medium.

Active adjustable terahertz multifunctional devices are crucial for the application of terahertz technology. In this paper, we propose a composite metasurface structure based on an indium antimonide metal octagonal pattern, which achieves different functional switching by controlling the phase state of indium antimonide material under different ambient temperatures. When indium antimonide exhibits in the dielectric state, by stacking and encoding the unit cell, the designed metasurface has the functions of two-beam splitting beam superposition, vortex beam and quarter beam superposition, and dual vortex beam superposition for circularly polarized and linearly polarized wave incidence.

Flexible manipulation terahertz beam based on an all-dielectric metasurface by utilizing addition and convolution algorithms.

The flexibly manipulated terahertz wave is currently a hot research topic. To address this challenge, we proposed an all-dielectric coding metasurface for shaping the terahertz wave including beam splitting, beam deflection, vortex beam generators, and a vortex beam and multi-beam splitting combination by combining addition with the convolution theorem. This work represents what we believe to be a new method of combining terahertz wave regulation with digital signal processing and opens up the versatile design ideas of multifunctional metadevices.

Reconfigurable three multi-mode terahertz metasurface.

We designed a three reconfigurable multi-mode terahertz metasurface based on a concentric elliptical ring structure. The proposed unit cell is a concentric elliptical ring composed of copper, vanadium oxide and photosensitive silicon from the inside ring to the outside ring. The conductivity of photosensitive silicon and vanadium oxide can be adjusted by changing the external operating temperature and pump light intensity.

Frequency regulated transmission-reflection integration modes of a terahertz metasurface.

The conventional transmission and reflection operating mode switching metasurface depends on phase change materials, which are often difficult to integrate with metasurface devices and work in real time. Here, we propose an integration of a transmission-reflection metasurface that can dynamically control beam direction and functions in both transmission and reflection modes by varying the frequency of the incident wave. Remarkably, the transmission and reflection modes of terahertz beam manipulation can be obtained by illuminating only the transmission side of the metasurface.

Terahertz Bessel beam generator.

The Bessel beam has broad application prospects in wireless energy transmission and high-speed communications. The traditional Bessel beam generation method has the problems of large volume, low efficiency, and complex manufacturing. To solve the above problems, we present a terahertz Bessel beam generator based on the reflective metasurface, which is composed of a metal pattern, dielectric layer, and bottom metal plate.

Terahertz all-dielectric metasurface sensor based on quasi-bound states in the continuum.

We proposed a quasi-bound states in the continuum (QBICs) metasurface to realize sensing in the terahertz band. It consists of silicon split ellipse cylinders with different short-long axes and a quartz substrate. By introducing two asymmetric split ellipse cylinders unit cells, magnetic dipole and electric quadrupole resonances of the proposed structure are investigated by multiple Pole theory.

Terahertz vortex beam generator carrying orbital angular momentum in both transmission and reflection spaces.

Vortex beam generators carrying orbital angular momentum (OAM) with both transmission and reflection modes has broad application prospects in full-space high data capacity communication and orbital angular momentum multiplexing systems. In this work, we proposed a vanadium dioxide (VO) assisted metasurface to independently produce and manipulate focused vortex transmission-reflection modes with different number of beams and focal lengths under right-handed circular polarized (RCP) wave incidence. The proposed metasurface generates the diagonal vortex beams, four vortex beams, and focused vortex beam for transmission mode at 1.

Terahertz device utilizing a transmissive geometric metasurface.

Due to potential applications in next generation high-capacity wireless communication systems, generating and controlling vortex beams carrying orbital angular momentum (OAM) has received considerable attention. In this work, a scheme is proposed to generate two/four splitting vortex beams and focusing vortex beams with different topological charges under left circularly polarized and right circularly polarized terahertz waves under incidence. The meta-unit cell consists of a two-flying-fish-shaped patterned metallic top layer and an identical metallic patterned bottom layer separated by a silica layer.

Simultaneous and independent regulation of circularly polarized terahertz wave based on metasurface.

A single metasurface-based device possessing multiple functionalities is highly desirable for terahertz technology system. In this paper, we design a reflective metasurface to generate switchable vortex beams carrying orbital angular momentum (OAM), focusing beams, focusing beams with arbitrary positions, and vortex beams with arbitrary topological charges in the terahertz region. By combining the spin decoupling principle and the phase addition theorem, the superposition states of OAM and focusing beams with arbitrary positions can be independent manipulated under right-handed and left-handed circularly polarized (LCP/RCP) waves illumination.

Switchable tri-function terahertz metasurface based on polarization vanadium dioxide and photosensitive silicon.

A terahertz switchable metasurface with the function of absorption and polarization conversion is proposed. It consists of metal pattern layer - dielectric layer - VO layer - dielectric layer - metal pattern layer, and the photosensitive silicon is embedded in the metal pattern. When VO is in insulated state, the metasurface behaves as a linear polarization converter.

Transmission and reflection bi-direction terahertz encoding metasurface with a single structure.

Most reported metasurfaces operate in single propagation direction mode (either transmissive mode or reflective mode), which hamper practical application. Here, we proposed a bi-directional operation coding metasurface based on a phase change material of a vanadium dioxide (VO) assisted metasurface. It can realize a dynamically invertible switch between the transmissive mode or reflective mode in the terahertz regime by changing the external ambient temperature.

Multi-beam and multi-mode orbital angular momentum by utilizing a single metasurface.

This paper proposes a novel metasurface that can simultaneously generate orbital angular momentum (OAM) beams with pre-designed different reflection directions, multi-beam and multi-mode under x-(y-) polarized terahertz wave incidence. The configuration of unit cell is made up of a hollow cross of Jesus structure as top layer, a PTFE substrate layer and a gold metal bottom plate. Theory of phase gradient distribution is derived and used to design multifunctional OAM metasurface.

Adjustable multichannel terahertz resonator.

Most reported terahertz devices are relatively simple to control by means of external applied electricity, light, heat, magnetism, etc. In the practical application of a terahertz system, the devices with a variety of adjustable methods are promising. In this paper, we design a rectangular-ambulatory-plane metal groove structure on apolymer polydimethylsiloxane (PDMS) substrate with graphene embedded in the metal grooves.

Diversified functions for a terahertz metasurface with a simple structure.

Here, we propose a new encoded metasurface with different predesigned coding sequences to dynamic manipulate terahertz wavefront and realize various functionalities including beam splitting, anomalous beam deflection, vortex beam generation, angle controlled single-beam deflection, angle controlled multi-beam deflection, angle-controlled vortex beam generation and multi-vortex beam generation. The far-field scattering patterns obtained by CST Microwave Studio demonstrate the behavior of the terahertz wave in each case and shows a high consistency with our theoretical prediction results. Due to the excellent properties of the diversified functionalities in a single structure at terahertz frequencies, the proposed encoded metasurface provides promising applications in terahertz multiple-input, multiple-output (MIMO) communication.

Switchable terahertz metasurface with polarization conversion and filtering functions.

A switchable metasurface with dual functions of polarization conversion and filtering is proposed in this paper. The designed structure is composed of a medium-metal-medium-metal-medium structure, and is embedded in the metal metasurface. When is an insulated state, this structure can perform linear polarization conversion under terahertz wave normal incidence, and it has good asymmetric transmission capabilities.

One-dimensional terahertz dielectric gradient metasurface for broadband spoof surface plasmon polaritons couplers: publisher's note.

This publisher's note contains corrections to Opt. Lett.46, 290 (2021)OPLEDP0146-959210.

One-dimensional terahertz dielectric gradient metasurface for broadband spoof surface plasmon polaritons couplers.

At present, most of the gradient metasurfaces used to construct surface plasmon polaritons (SPPs)/spoof SPPs (SSPs) couplers are usually compact metal antennas working under reflection and transmission. In reflection mode, meta-couplers link propagating waves and surface waves (SWs), and SWs will undergo significant scattering before coupling to an Eigen SPP in the target system. In transmission mode, metal meta-couplers will encounter complex multilayer designing at the microwave/terahertz region and metal absorption loss at optical frequencies.

Simple terahertz vortex beam generator based on reflective metasurfaces.

Orbital angular momentum (OAM) is an effective way to increase wireless communication capacity. The existing OAM mainly focuses on the optical and microwave frequency domain. In this letter, a reflective metasurface is proposed to generate an OAM vortex wave beam in the terahertz region with different topological charges.

BiOSe for broadband terahertz wave switching.

Many modern terahertz systems require dynamic manipulation of a terahertz wave. We proposed a terahertz wave switch based on a / structure. The transmittance and conductivity characteristics of the in a terahertz region have been measured by terahertz time-domain spectroscopy and analyzed using the Drude model.

Multifunctional reflective dielectric metasurface in the terahertz region.

The recent emergence of digital coding metasurfaces has significantly simplified the design of functional devices and manipulated electromagnetic waves digitally. In this paper, we propose a dielectric coding metasurface with different functions, which is implemented by a metasurface with specific coding sequences. It is composed of a three-dimensional T-shaped dielectric block placed on a metal plate.

Dual-band passband terahertz filter based on multilayer metamaterial.

We have theoretically verified the design of dual-band passband terahertz filter using multilayer metamaterial. The top and bottom layers are composed of periodically branching structure metallic patterns, which are exactly the same. The middle layer consists of a periodically metallic square aperture.

Enhancement of silicon modulating properties in the THz range by YAG-Ce coating.

YAlGaO:Ce,V (YAG:Ce) has excellent chemical stability and unprecedented luminous efficiency. Its strong photoresponsive property is thoroughly utilized in designing excellent optical information storage device. Here, the remarkable photoconductivity of YAG:Ce is exploited to demonstrate a hybrid YAG:Ce-silicon device that shows high speed terahertz wave spatial modulation.

Hollow-petal graphene metasurface for broadband tunable THz absorption.

We propose a tunable and broadband terahertz (THz)-wave absorber based on the graphene metasurface, which consists of a layer of graphene-hollow-petal structure array and a bottom copper film separated by a 20-μm-thick lossless thermo plastic olefin polymer of amorphous structure layer. The mechanism of such a THz-wave absorber is numerically investigated and theoretically analyzed with the aid of a modified Fabry-Perot resonant model and finite element method. A large absorption efficiency of more than 90% in a frequency range of 2.

A Diaminopillar[5]arene-Based Macrobicyclic Molecule: Synthesis, Characterization and A Lock-Key Story.

A new macrobicyclic molecule (BC-DAP5), consisting of a diaminopillar[5]arene cavity and a fused ring, was successfully constructed using a Grubbs metathesis reaction. Further studies indicated that BC-DAP5 possessed a unique molecular behavior, showing a response to acid/base stimuli. In BC-DAP5, protons (acid) acted as a lock, locking the fused ring out of the cavity (pillar[5]arene), and a base served as the key, making the fused ring switch in or out freely.

Highly effective electrosynthesis of hydrogen peroxide from oxygen on a redox-active cationic covalent triazine network.

Direct electrosynthesis of hydrogen peroxide (H2O2) by oxygen reduction is a green and safe strategy to replace the traditional anthraquinone process. Herein, we have designed a two-dimensional redox-active cationic covalent triazine network to be used directly as a cost-effective metal-free electrocatalyst for the oxygen reduction reaction (ORR) to form H2O2. Such a dicationic 2D polymer possesses a porous structure with pore diameters of 2-10 nm and a total N content of 13.