Spoof Surface Plasmon Research Articles

Photonic Spin‐Hall Logic Devices Based on Programmable Spoof Plasmonic Metamaterial

AbstractThe entanglement of the momentum of light with its spin at interfaces or inside structured media, known as the photonic spin‐Hall effect, holds great promise for various applications, such as beam splitting, focusing, and polarization detection. However, the photonic spin‐Hall effect remains unexplored in the field of logic operation. In this work, the photonic spin‐Hall effect of spoof surface plasmon polaritons (SSPPs) in programmable metamaterial is demonstrated. Moreover, photonic spin‐Hall logic devices based on programmable spoof plasmonic metamaterial are designed, enabling the control of energy flow through the utilization of both spin and digital coding, with examples including SSPPs logic gates such as the “AND” gate, the “NIMPLY” gate (A AND NOT B), the “OR” gate, and the “NOT” gate. The findings introduce the combination of digital coding metamaterial with the photonic spin Hall effect, which offers a powerful and flexible platform for controlling electromagnetic waves in information processing.

Multifunctional design of hierarchical corrugated metamaterial absorber realized by carbon fiber stitching

Carbon fiber (CF) which has both mechanical and electromagnetic (EM) characteristics can achieve multiple functions by special designing, such as load bearing and EM wave absorption. In this work, based on the excellent mechanical properties of hierarchical corrugated sandwich structure (HCSS), a novel CF interlaminar reinforced hierarchical corrugated metamaterial absorber (HCMMA) is constructed. By stitching CF arrays onto the core member face of HCSS, the spoof surface plasmon polaritons (SSPPs) structure is constructed, endowing HCSS with EM wave absorption ability and enhancing its interlaminar mechanical properties. Simulation and experimental results show that the proposed structure achieves efficient absorption (average over 90 %) of 4 - 12 GHz EM wave with an incident angle of 0 - 60°, which realized by the dielectric loss of EM wave and local strong E-filed formed by SSPPs structure. In addition, the stitching of CF arrays effectively limit the local buckling-debonding deformation region of the core member face, which greatly improves its mechanical performances. Thereby the compressive strength and specific compressive strength of the proposed structure is increased by 32.7 % and 16.7 %, respectively. Based on the multifunctional design characteristics of CF, the proposed structure effectively expands the application of composite sandwich structures in the field of multifunctional design.

Dual-Band Large-Frequency Ratio Power Divider Using Mode Composite Transmission Line for 5G Communication Systems

In this paper, a novel kind of mode composite transmission line (MC-TL) is proposed, and a dual-band power divider with a large frequency ratio using this novel MC-TL for 5G communication systems was developed. The proposed MC-TL was developed using spoof surface plasmon polaritons (SSPPs) and a corrugated substrate-integrated waveguide (CSIW) transmission line, which supports both a surface plasmon mode and TE10 mode, independently. The surface plasmon mode operates in the grooves of the surface metal layer, while the TE10 mode works in the substrate between two metal layers. These two parts can transmit different modes at independent frequencies. This structure can be used in dual-band transmission lines with a high frequency ratio. The characteristics and design of the MC-TL (SSPPs and CSIW) are analyzed and illustrated. The MC-TL was fabricated and measured to demonstrate its performance. Moreover, based on the proposed MC-TL, a dual-band power divider with a large frequency ratio (operating at 3 GHz and 28 GHz simultaneously) was also designed and fabricated. It can cover the frequency of a fifth-generation communication system perfectly. The measured outcomes align closely with the simulated results, demonstrating robust agreement and showcasing excellent transmission capabilities.

A low-profile high-isolation endfire MIMO antenna based on spoof surface plasmon polaritons for X-band applications

This work proposes a three-port, low-profile, coplanar endfire multiple-input-multiple-output (MIMO) antenna based on spoof surface plasmon polaritons (SSPPs). The proposed antenna comprises a coplanar waveguide (CPW)-fed SSPPs transmission line (TL). A transition to transform the CPW quasi-TEM mode to the SSPPs mode. The radiator section with asymmetric discontinuities converts the bounded SSPPs waves into radiating waves. The proposed MIMO antenna exploits the inherent feature of high isolation in the SSPPs TL due to its strong field confinement competency. Wider beamwidths for ample azimuth and elevation coverage with a stable pattern in the endfire direction are achieved in the 9.52–11.23 GHz operating band. In the operating band, the MIMO antenna has an average realized gain of 6 dBi. Mainly, it has high isolation below -35 dB (measured) in the operating range, a maximum envelope correlation coefficient (ECC) of 1.5 × 10−3, and a total active reflection coefficient (TARC) value below 0.3. The measured results are closely matched with the simulated ones in terms of S-parameters, radiation pattern, ECC, TARC, and CCL.

A compact and narrow-band bandpass filter based on substrate integrated waveguide and spoof surface plasmon polaritons for millimeter-wave applications

This paper presents bandpass filter (BPF) comprising substrate integrated waveguide (SIW) and spoof surface plasmon polaritons (SSPPs), achieving miniaturized size, low insertion loss in the millimeter-wave band. SIW with single-slotted SSPP structure is employing to obtain the transmission zero (TZ) at the low-frequency part, and by introducing the SIW with rhombic periodic walls to enhance the low-frequency rejection. The target passband and TZ of the high-frequency part are realized by increasing the number of etching slots. Furthermore, we innovatively incorporate nonradiative (NR) slots etched below the SSPP structure to gain high out-of-band rejection level. SIW with rhombic periodic walls and slotted SSPP structure as one unit cell is analyzed and demonstrated. Ultimately, the two SIW unit cells are cascaded together to get better out-of-band rejection characteristics and serve as our final design. To validate the proposed design, the BPF prototype is fabricated and measured, showing good electrical performance in terms of high selectivity, low loss, and compact size.

Design and optimization of spoof surface plasmon polaritons based multi-octave power amplifier using PSO algorithm

In this article, we explore how spoof surface plasmon polaritons (SSPP) theory can be applied to the design of active radio frequency (RF) power amplifiers (PAs). This work utilizes SSPP structures for the design of both input and output matching networks for a multi-octave PA. In order to perform proper impedance matching, the properties of SSPP unit structures are presented and analyzed. A description of the performance of the initial PA has been provided and discussed. Additionally, particle swarm optimization (PSO) is used to further enhance the performance of the PA circuit. In comparison with an embedded gradient method in a commercial tool, the PSO method results in a better optimization result. The fabricated PA is tested and the results indicate that in the frequency range of 0.5 GHz to 2.9 GHz, it achieves an output power of 40.4 dBm to 41.2 dBm, a power added efficiency of 60.5–65%, and an output gain exceeding 10 dB. Compared to recent work, the multi-octave PA in this work broadens bandwidth while maintaining high output power and PAE. To further verify the linearity of the SSPP-based PA, digital pre-distortion (DPD) is implemented. As a result of the DPD, the linearity of the SSPP PA was greatly enhanced.

A Wireless Non-Metallic Pipeline Liquid Level Sensor Based on Spoof Surface Plasmon Polaritons

A Wireless Non-Metallic Pipeline Liquid Level Sensor Based on Spoof Surface Plasmon Polaritons

A Liquid Level Positioning System For Non-Metal Containers Based on Localized Spoof Surface Plasmon

A Liquid Level Positioning System For Non-Metal Containers Based on Localized Spoof Surface Plasmon

Microscopy of terahertz spoof surface plasmons propagating on planar metamaterial waveguides

Surface plasmon polaritons (SPPs) are electromagnetic waves that have attracted significant interest owing to their subwavelength confinement and the strong field enhancement that they provide. Yet in the terahertz (THz) frequency region of the spectrum, which is well below the plasma frequency of metals, these surface waves are characterized by extremely weak confinement that has severely limited their exploitation for information processing and sensing. One means to circumvent this limitation is through subwavelength structuring of a metallic surface, which can thereby be engineered to support the propagation of spoof surface plasmon polaritons (SSPPs) that closely mimic the properties of SPPs. In this work, we report the design and experimental characterization of an ultra-thin metamaterial planar waveguide that supports SSPPs at THz frequencies. Finite-element method simulations are shown to predict the excitation of SSPPs on the surface of our devices under free-space illumination at 3.45 THz. We investigate these structures experimentally using THz scattering-type scanning near-field microscopy (THz-s-SNOM) to map directly the out-of-plane electric field associated with the propagation of SSPPs on the surface of the waveguides. Our work paves the way for the future development of plasmonic integrated circuit technologies and components operating in the THz frequency band.

Refractive index sensing of spoof surface plasmon polaritons excited on graphene strips based on cylindrical dielectric metasurface coupling

In this paper, we present a novel terahertz plasmonic sensing concept that utilizes a metasurface coupler to excite spoof surface plasmon polaritons (SSPs) modes on graphene strips. The dielectric metasurface unit cell consists of two silicon cylindrical rods with different radii on a quartz substrate. Vertically incident terahertz waves are deflected by the metasurface, resulting in a transverse wave-vector within the substrate that matches the SSPs wave-vector supported by the graphene strips. This enables efficient excitation of SSPs modes on the graphene strips surface, leading to absorption resonances in the range of 0.420–0.430 THz with a high quality (Q) factor of 152. We then applied this device for refractive index sensing, and the investigation results indicate that the high Q resonances in the absorption spectrum experience shifts with changes in the refractive index of the target substance, with a sensitivity of 110 GHz/RIU. The designed structure in this study exhibits significant potential for applications in trace substance absorption spectrum detection.

Broadband Balanced-to-Balanced Filtering Power Divider Using HMSIW-SSPP Transmission Line.

In this paper, a novel broadband balanced-to-balanced (BTB) filtering power divider (FPD) utilizing the half-mode substrate-integrated waveguide and spoof surface plasmon polariton (HMSIW-SSPP) hybrid transmission line is introduced. Initially, a new HMSIW-SSPP unit cell is proposed, demonstrating a lower upper cut-off frequency compared to the classical HMSIW-SSPP unit cell. Building upon this unit cell, a bandpass BTB FPD is devised employing dual-layer stacked substrates, enabling independent control over the passband's lower and upper cut-off frequencies through specific physical dimensions. Additionally, the incorporation of isolation resistors and defected ground structures in the BTB FPD enhances differential-mode isolation and common-mode (CM) suppression between output ports. A manufactured and tested BTB FPD prototype validates this design method, showcasing a broad fractional bandwidth of 52.31% (6.72-11.48 GHz), output port isolation surpassing 14.25 dB, and transmitted CM suppression exceeding 34.05 dB.

Shared‐Aperture 2‐Bit Coding Metasurface for Simultaneous Manipulation of Space Wave and Surface Wave

AbstractA shared‐aperture 2‐bit coding metasurface for simultaneously and independently manipulating space wave and surface wave is proposed in this paper. When the proposed coding metasurface is expected to modulate space wave, the unit cells can control the reflection phase. The reflected wave becomes various according to the specific coding sequence. When the proposed coding metasurface acts as spoof surface plasmon polaritons (SSPP) transmission line, the unit cells can modulate the surface impedance. With periodic modulation to the surface impedance, electromagnetic wave can be radiated into free space and the radiation beam scans as frequency changes. Space wave modulator works at 22.5 GHz, while the surface wave modulator works during the frequency range of 6.5–11.4 GHz. The total scanning angle of the radiated beam of surface wave modulator covers from −54° to 52°, with an average gain of 10.64 dBi. Simultaneous manipulation of both space wave and surface wave by a single metasurface makes the proposed device promising in the new radar and satellite communication systems with compact requirement.

Excitation of Terahertz Spoof Surface Plasmons on a Roofed Metallic Grating by an Electron Beam.

In this paper, both fundamental SSP modes on a roofed metallic grating and its effective excitation of the bounded SSP mode by an injected electron beam on the structure are numerically examined and investigated in the THz regime. Apart from the bounded SSP mode on the metallic grating with open space, the introduced roofed metallic grating can generate a closed waveguide mode that occupies the dispersion region outside the light line. The closed waveguide mode shifts gradually to a higher frequency band with a decreased gap size, while the bounded SSP mode line becomes lower. The effective excitation of the bounded SSP mode on this roofed metallic grating is also implemented and studied by using a particle-in-cell simulation studio. The output SSP power spectrums with various gap sizes by the same electron beam on this roofed metallic grating are obtained and analyzed. The simulation results reveal that the generated SSP spectra show a slight red shift with a decreased gap size. This work on the excitation of the SSP mode using an electron beam can benefit the development of high-power compact THz radiation sources by utilizing the strong near-field confinement of SSPs on metallic gratings.

Dispersion curve engineering for automated topology design of a unit cell in spoof surface plasmon polaritons

In this paper, an automatic design method is proposed for unit cell in spoof surface plasmon polaritons (SSPP) with an almost arbitrary dispersion curve. In this method, the pixel configuration is considered for the unit cell and, by using the binary particle swarm optimization method, the proper topology of the unit cell is explored so as to reach the target dispersion curve. Unlike the traditional method of controlling the dispersion curve, which is performed based on changing the geometric parameters of the predetermined unit cell, in this method, there is no need to know the shape of the unit cell, and the dispersion curve of the modes of SSPP unit cell can be controlled independently with more freedom. Two unit cell samples are designed in order to show the efficiency of the procedure. In the first sample, the dispersion curve is designed to have the lowest asymptotic frequency; in the second sample, the dispersion curve of the second mode is controlled independently from the first mode and is changed arbitrarily. SSPP transmission lines which are related to the unit cells of the two samples are designed, and it is demonstrated that measurement and simulation results are greatly in line with each other.

High gain and high-efficiency compact resonator antennas based on spoof surface plasmon polaritons

Abstract We proposed a high gain high-efficiency compact metallic resonator antenna operating at even-mode meander line spoof surface plasmon polaritons (MLSSPPs). The high radiation efficiency is caused by the bulk of fields crowded in lossless air near the antenna rather than in lossy dielectric as in conventional dielectric resonator antennas (DRAs). The proposed antenna also exhibits compact size because of its high effective refractive index. A reliable equivalent circuit model is proposed for the design of the resonator antenna with basic mode of half wavelength resonant mode. As an example, a meander-line SSPP antenna is designed, fabricated and measured. Both the simulated and measured results show the advantages of high efficiency and compact volume. In addition, the antenna achieves higher gain and wider relative bandwidth per wavelength cube volume compared with its counterparts. This method provides a good alternative for designing DRAs.

Fabrication and characterization of delay lines with spoof surface plasmon polariton waveguide coupled with C-shaped metamaterials for microwave integrated circuits

Abstract Here, we proposed two delay lines consisting of spoof Surface Plasmon Polariton (sSPP) waveguides and C-shaped metamaterials (C-MMs). The delay lines, namely OFF and ON devices, were designed and fabricated. On the OFF device, an sSPP waveguide is capacitively coupled to the C-MMs via an air gap on a high-resistivity silicon substrate. On the ON device, a connection is established between the C-MMs and the sSPP waveguide by metal connectors. The difference in the electrical properties in the coupling between the C-MMs and the sSPP waveguide creates a large phase contrast between the ON and OFF delay lines. The structural design was performed using a numerical calculation based on a commercial finite element solver. We successfully fabricated and characterized delay lines with phase differences equal to tens of degrees between the ON and OFF devices in the target frequency range of 2-6 GHz, while maintaining the original transmittance properties. The promising applications of the delay lines are a phase shifter or modulator when integrating with suitable switches.

A terahertz metamaterial biosensor based on spoof surface plasmon polaritons transmission line for avian influenza virus detection

A highly sensitive terahertz biosensor based on spoof surface plasmon polaritons for avian influenza virus detection is presented in this paper. The sensor utilizes a grating structure to support spoof plasmon modes with high-quality factors, enabling detection at 1.93 THz with a Q-factor of 690. The slow-wave transmission lines (SWTL) are connected to a metamaterial unit cell to achieve strong field confinement and resonance at terahertz frequencies. Various types of the H1N1, H5N2, and H9N2 are considered as material under test which is placed over the sensor. The main elements for controlling the resonance and increasing the Q-factor are the width of the gap and the unit-cell and the parametric studies show that the selected dimensions are optimum for this sensor. The high sensitivity is attributed to the excitation of spoof plasmons that concentrate the terahertz field within micro-scale regions, interacting with minute amounts of analyte. The full-wave method of the finite integrated technique (FIT) as a high-accuracy time domain method is used for the simulation of the proposed structure and it is compared with the finite element method (FEM) for confirming the results. Moreover, the transmission line model (TL) and circuit model (results) are extracted which prove the truth of the full-wave results. The average sensitivity (Savg) of this sensor for material in the range of 1.1 to 1.5 is obtained up to 8 %. This work demonstrates the application of plasmonic metamaterials to terahertz biosensing for virus detection with high sensitivity.

Mush-Room Structures–Loaded Coplanar Waveguide Spoof Surface Plasmon Polariton with Reduced Longitudinal Length

Mush-Room Structures–Loaded Coplanar Waveguide Spoof Surface Plasmon Polariton with Reduced Longitudinal Length

Electronic excitation of high-order spoof surface plasmons on metallic grating at terahertz frequencies

High-order spoof surface plasmon (SSP) mode on corrugated metallic surfaces can find many interesting applications, such as in imaging, sensing, transmission and enhanced radiation source, etc. In this paper, an efficient excitation method of the high-order SSP mode by using an injected electron beam on the uniform rectangular metallic grating is proposed and investigated numerically. Based on the matched wave momentum between the SSP mode and the electron beam, both the fundamental and high-order SSP modes can be excited on the structure by using a single injected electron beam. Numerical simulation results indicate that the maximum electric field intensity of the generated high-order SSP mode is about two orders higher than that of the fundamental SSP mode. In addition, the peak power of the excited high-order SSP mode is almost two times that of the fundamental SSP mode power by the same energy electron beam, which demonstrates the obvious advantage of the high-order SSP electronic excitation approach compared to the previous fundamental SSP mode excitation on the structure. The central working frequency of high-order SSP power spectrum is about three times that of the fundamental SSP power spectrum. Moreover, the influences of the injected electron beam energy on the excited SSP power spectrum are analyzed specifically. It is shown that the generated SSP power spectrum demonstrates a blue shift with the decreased working voltage of the electron beam simultaneously, with its peak power increasing. However, the working bandwidth is narrowed with decreased beam voltage, which further reveals its working mechanism of presented electronic excitation of the SSP mode. The presented studies provide a new method to excite a high-order SSP mode on the metallic grating, which can find some potential applications in high-sensitivity sensing, deep sub-wavelength waveguide, and many others in terahertz spectra.

Full-Space and High-Scanning Rate Leaky-Wave Antenna Based on Spoof Surface Plasmon Polaritons

Full-Space and High-Scanning Rate Leaky-Wave Antenna Based on Spoof Surface Plasmon Polaritons