Jiayuan Lu

Bio: Jiayuan Lu is an academic researcher from Southeast University. The author has contributed to research in topics: Surface plasmon polariton & Microstrip. The author has an hindex of 6, co-authored 11 publications receiving 83 citations.

Design of Miniaturized Antenna Using Corrugated Microstrip

Abstract: We present a new method to design miniaturized antennas using a corrugated microstrip (CM) line, which shows good slow wave characteristic in the required frequency band. To achieve good radiating behavior and low profile simultaneously, CM is employed as the resonating part of the antenna. The impact of the CM propagation constant on the antenna is discussed in detail. The miniaturized antenna is designed and measured to verify the feasibility of the design method. The measured results show that the proposed antenna can achieve a beamwidth of 70° in E-plane and 75° in H-plane with a gain tolerance of 3 dB, and the realized peak gain level at the central frequency is 5.15 dBi, which have good agreements to the expected designs. Such results indicate that the proposed antenna exhibits excellent radiation characteristics at the resonant mode. The effective size of the proposed miniaturized antenna is $0.16\lambda _{0}\times 0.16 \lambda _{0}\times 0.04 \lambda _{0}$ at 9 GHz, in which $\lambda _{0}$ is the wavelength of the central frequency.

Crosstalk Suppression Based on Mode Mismatch Between Spoof SPP Transmission Line and Microstrip

Abstract: We propose an efficient method to suppress the crosstalk based on the mode mismatch between spoof surface plasmon polariton (SPP) transmission line (TL) and microstrip. Since microstrip and spoof SPP TL support quasi-transverse electromagnetic (quasi-TEM) wave and transverse magnetic (TM) wave, respectively, the transmitting electromagnetic (EM) energy can hardly be coupled between these two kinds of TLs, which helps to reduce the crosstalk. For the cases of weak and strong coupling, two kinds of structures of spoof SPP TLs are designed. To verify the performance of crosstalk suppression, two samples of the coupled TLs are presented and fabricated. Simulated and experimental results show that the crosstalk of both strong and weak coupling is reduced by approximately 35 and 30 dB, respectively, by introducing the spoof SPP TL into the microstrip pair. Thus, crosstalk in traditional circuits can be alleviated by the mode mismatch between spoof SPP TLs and microstrips, which is significant for high-speed and high-density integrated systems.

A novel spoof surface plasmon polariton structure to reach ultra-strong field confinements

Abstract: Ultrathin corrugated metallic structures have been proved to support spoof surface plasmon polariton (SPP) modes on two-dimension (2D) planar microwave circuits. However, to provide stronger field confinement, larger width of strip is required to load deeper grooves, which is cumbersome in modern large-scale integrated circuits and chips. In this work, a new spoof SPP transmission line (TL) with zigzag grooves is proposed. This new structure can achieve stronger field confinement compared to conventional one with the same strip width. In other words, the proposed spoof SPP TL behaves equivalently to a conventional one with much larger size. Dispersion analysis theoretically indicates the negative correlation between the ability of field confinement and cutoff frequencies of spoof SPP TLs. Numerical simulations indicate that the cutoff frequency of the proposed TL is lower than the conventional one and can be easily modified with the fixed size. Furthermore, two samples of the new and conventional spoof SPP TLs are fabricated for experimental demonstration. Measured S-parameters and field distributions verify the ultra-strong ability of field confinement of the proposed spoof SPP TL. Hence, this novel spoof SPP structure with ultra-strong field confinement may find wide applications in microwave and terahertz engineering.

Compact filters with adjustable multi-band rejections based on spoof surface plasmon polaritons

Abstract: Owing to the gorgeous features of planar design, strong field confinement, and compatibility with traditional microwave devices, spoof surface plasmon polaritons (SSPPs) have been developing at a rapid pace in modern microwave technologies. Band-rejection filters, especially multi-band rejection filters, are a significant ecosystem of SSPPs to be designed. Here, we firstly propose compact multi-band rejection filters, including dual-band and triple-band, through the addition of interdigital capacitance loaded loop resonators (IDCLLRs) into the grooves of the corrugated SSPP transmission line (TL). Compared to traditional metamaterial particles like split ring resonators (SRRs) and complementary SRRs (CSRRs) with the same size, IDCLLRs possess excellent merits of lower resonant frequency, larger dynamic range, and more tunable parameters, which enable the proposed device to be more compact and have more freedom for adjusting bandwidths. Both the simulated and experimental results demonstrate the high performance of two multi-band rejection filters, which can provide wide stop-bandwidth (a maximum relative bandwidth of up to 9.5% for the dual-band filter and 8.8% for the triple-band filter) and high isolation (the isolation of both filters can be less than −30 dB and the maximum isolation of up to −60 dB for the dual-band filter and −58 dB for the triple-band filter). The compact SSPP filters with adjustable multi-band rejections may greatly advance progress towards SSPP-based devices and integrated systems.

Integrated multi-scheme digital modulations of spoof surface plasmon polaritons

Abstract: The future wireless communications require different kinds of modulation functions to be integrated in a single intelligent device under different scenarios. Here, we propose a multi-scheme digital modulator to achieve this goal based on integrated spoof surface plasmon polaritons (SPP) in different frequency bands. By constructing switchable spoof SPP units, the propagating wave in the proposed spoof SPP waveguide can be manipulated in amplitude domain, frequency domain, and phase domain. As a proof of concept, the integrated multi-scheme digital modulator is experimentally verified to achieve at least three kinds of modulations, including amplitude shift keying, phase shift keying, and frequency shift keying, in a single digital spoof plasmonic waveguide. The simulated and measured results show that the modulator has excellent property of field confinement and is capable of frequency-domain modulation. Hence, the multi-scheme modulation property makes the proposed SPP digital modulator be an effective and reliable candidate for efficient manipulations of SPP waves and for advanced modulation technology

A plasmonic route for the integrated wireless communication of subdiffraction-limited signals.

Abstract: Perfect lenses, superlenses and time-reversal mirrors can support and spatially separate evanescent waves, which is the basis for detecting subwavelength information in the far field. However, the inherent limitations of these methods have prevented the development of systems to dynamically distinguish subdiffraction-limited signals. Utilizing the physical merits of spoof surface plasmon polaritons (SPPs), we demonstrate that subdiffraction-limited signals can be transmitted on planar integrated SPP channels with low loss, low channel interference, and high gain and can be radiated with a very low environmental sensitivity. Furthermore, we show how deep subdiffraction-limited signals that are spatially coupled can be distinguished after line-of-sight wireless transmission. For a visualized demonstration, we realize the high-quality wireless communication of two movies on subwavelength channels over the line of sight in real time using our plasmonic scheme, showing significant advantages over the conventional methods. The unique properties of surface plasmons enable wireless transmission of signals separated by less than one wavelength. Until recently, it was considered impossible to distinguish signals with sub-wavelength separation, due to the so-called diffraction limit. This limit can be overcome using artificial structures called metamaterials, but it is difficult to integrate these new components with conventional electronics. Now, Tie Jun Cui at Southeast University in Nanjing, China, and co-workers have shown that sub-wavelength signals can be transmitted using surface plasmon polaritons (SPPs)—combinations of electromagnetic waves and charge motion that travel on the surface of a metal. By encoding signals in ‘spoof’ SPPs that mimic natural SPPs, the team were able to wirelessly transmit two high-definition movies on channels just one-tenth of a wavelength apart, even with a concrete wall in the way.

Active digital spoof plasmonics

Abstract: Digital coding and digital modulation are the foundation of modern information science. The combination of digital technology with metamaterials provides a powerful scheme for spatial and temporal controls of electromagnetic waves. Such a technique, however, has thus far been limited to the control of free-space light. Its application to plasmonics to shape subwavelength fields still remains elusive. Here, we report the design and experimental realization of a tunable conformal plasmonic metasurface, which is capable of digitally coding and modulating designer surface plasmons at the deep-subwavelength scale. Based on dynamical switching between two discrete dispersion states in a controlled manner, we achieve digital modulations of both amplitude and phase of surface waves with nearly 100% modulation depth on a single device. Our study not only introduces a new approach for active dispersion engineering, but also constitutes an important step towards the realization of subwavelength integrated plasmonic circuits.

Excitation of Surface Plasmon Resonance on Multiwalled Carbon Nanotube Metasurfaces for Pesticide Sensors.

Abstract: With the rapid advances in functional optoelectronics, the research on carbon-based materials and devices has become increasingly important at the terahertz frequency range owing to their advantages in terms of weight, cost, and freely bendable flexibility. Here, we report an effective material and device design for a terahertz plasmonic metasurface sensor (PMS) based on carbon nanotubes (CNTs). CNT metasurfaces based on silicon wafers have been prepared and obvious resonant transmission peaks are observed experimentally. The enhanced resonant peaks of transmission spectra are attributed to the surface plasmon polariton resonance, and the transmission peaks are further well explained by the Fano model. Furthermore, the different concentration gradients of pesticides (2,4-dichlorophenoxyacetic and chlorpyrifos solutions) have been detected by the designed PMSs, showing the lowest detection mass of 10 ng and the sensitivities of 1.38 × 10-2/ppm and 2.0 × 10-3/ppm, respectively. Good linear relationships between transmission amplitude and pesticide concentration and acceptable reliability and stability have been obtained. These materials and device strategies provide opportunities for novel terahertz functional devices such as sensors, detectors, and wearable terahertz imagers.

Metamaterial and Helmholtz coupled resonator for high-density acoustic energy harvesting

Abstract: High-density acoustic energy harvesting is one of the power solutions for wireless sensor network nodes in the Internet of Things. In this paper, we present a novel metamaterial and Helmholtz coupled resonator (MHCR) to enhance the sound energy density by energy focusing and pressure amplification. Metamaterial refers to a type of structural composite material, usually periodic. The local modification of the material by introducing a defect can make the wave at the defect band frequency be confined to the defect area to achieve acoustic energy focusing. The Helmholtz resonator is added to the defect of the metamaterial to amplify the focused sound waves. The variation in channel pressure causes the plug of the air in the neck to oscillate in and out, producing adiabatic compression and expansion of the air in the cavity to amplify sound pressure. The mathematical models of band structure, resonant frequency, vibration amplitude with vibroacoustic coupling and output voltage with electromechanical coupling are developed to design MHCR. The maximum voltage of the coupled energy harvester was about 3.5 times that of the maximum voltage of the metamaterial energy harvester. Field tests illustrated the effectiveness of the proposed MHCR with the maximum transmission ratio of 30.83 mV/Pa in mechanical noise environment, which was 48 times the maximum transmission ratio of the metamaterial energy harvester in the chirping of cicadas.