A Spoof Surface Plasmon Polaritons (SSPPs) Based Dual-Band-Rejection Filter with Wide Rejection Bandwidth.

This paper presents a novel single-layer dual band-rejection-filter based on Spoof Surface Plasmon Polaritons (SSPPs). The filter consists of an SSPP-based transmission line, as well as six coupled circular ring resonators (CCRRs) etched among ground planes of the center corrugated strip. These resonators are excited by electric-field of the SSPP structure. The added ground on both sides of the strip yields tighter electromagnetic fields and improves the filter performance at lower frequencies. By removing flaring ground in comparison to prevalent SSPP-based constructions, the total size of the filter is significantly decreased, and mode conversion efficiency at the transition from co-planar waveguide (CPW) to the SSPP line is increased. The proposed filter possesses tunable rejection bandwidth, wide stop bands, and a variety of different parameters to adjust the forbidden bands and the filter's cut-off frequency. To demonstrate the filter tunability, the effect of different elements like number (n), width (WR), radius (RR) of CCRRs, and their distance to the SSPP line (yR) are surveyed. Two forbidden bands, located in the X and K bands, are 8.6-11.2 GHz and 20-21.8 GHz. As the proof-of-concept, the proposed filter was fabricated, and a good agreement between the simulation and experiment results was achieved

Spoof Surface Plasmon Polariton Based THz Circuitry

Terahertz, abbreviated as THz, is defined as the frequency band spanning from 300 GHz to 10 THz, which is located between the microwave from the electronic side of the electromagnetic (EM) spectrum to mid-Infra-Red on the photonic side of the EM spectrum. As accelerated research and innovations over the past seven decades have resulted in widespread commercialization of both electronic and photonic components, THz band has remained underdeveloped, underexploited, and mostly unallocated by the Federal Communications Commission (FCC). Though certain definitive merits of EM waves at THz have evoked interests of physicists, chemists, biologists and material scientists to deploy THz in Time-Domain Spectroscopy (TDS), bio-sensing, and classical imaging applications, the field of THz circuits (also known as THz electronics) has continued to remain in embryonic stage due to the speed limitations of conventional Silicon and compound semiconductor devices like Field Effect Transistors (FETs), Hetero-junction Bipolar Transistors (HBTs), and Hot Electron Mobility Transistors (HEMTs). On the other hand, conventional photonic devices cannot be readily adopted to design new THz circuits and systems. Our research vision in THz circuits and systems is to study the meta-material properties of THz in various forms of sub-wavelength structures and exploit those unique properties to invent the designs of large THz systems like the THz switch, Analog-to-Digital Converter (ADC), etc. The potential large bandwidth and high propagation speed helps photonic circuitry to be proposed against the above-mentioned challenges faced by its electronic counterpart. Optical-assisted as well as all-optical systems in various forms have been reported to realize different data-processing functionalities. For example, analog-to-digital converters (ADC) with the potential of high speed operation have been demonstrated by optical-assisted or all-optical approaches. Photonic logic has also been reported in numerous works by coding the Boolean information in the amplitude, phase or wavelength of the optical signals. Despite these efforts, however, the key element to address the fundamental deficiencies of CMOS circuit remained missing. The use of optical frequencies in these works brought about common shortcomings including dimension mismatch, lack of coherent detection, inflexibility, susceptibility to mechanical and environmental variations, and the presence of bulky optical elements (i.e., mirrors, beam splitters, lenses, etc.). More seriously, these works inherited sequential circuit designs directly from CMOS. It indicates that the cumulative delay still dominated the speed performance, which prevented further decrease of the circuit latency. In light of these problems, we foresee the implementation of THz circuitry as the next reasonable step to take in designing high-speed analog as well as digital circuits. Spoofed Surface Plasmon Polariton (SSPP) is known as a pseudo-surface mode in THz frequencies that mimics the slow wave nature and localized E-M field distribution of the plasmon mode typically observed in optical domain. By introducing periodic corrugations on the surfaces of a metal-dielectric-metal structure, SSPP mode is realized for propagating THz signal, and its mode dispersion is strongly dependent on the geometric dimensions as well as the material properties of the architecture. Recently propagation of THz wave utilizing Spoof surface plasmon polariton (SSPP) earned a great deal of attention due to the ability of SSPP modes to guide THz waves at very low dispersion. In this research, we exploit and investigate the SSPP modes in different periodic structure and utilizing them in different structure to introduce new THz devices, such as, polarization rotator, THz switch, ADC, etc.PHDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/144105/1/mahdia_1.pd

Towards Faster Data Transfer by Spoof Plasmonics

With the emergence of complex architectures in modern electronics such as multi-chip modules, the increasing electromagnetic cross-talk in the circuitry causes a serious issue for high-speed, reliable data transfer among the chips. This thesis aims at developing a cross-talk resilient communication technology by utilizing a special form of electromagnetic mode, called spoof surface plasmon polariton for information transfer. The technique is based on the fact that a metal wire with periodic sub-wavelength patterns can support the propagation of confined electromagnetic mode, which can suppress cross-talk noise among the adjacent channels; and thus outperform conventional electrical interconnects in a parallel, high channel density data-bus. My developed model shows that, with 1 THz carrier frequency, the optimal design of cross-talk resilient spoof plasmon data-bus would allow each channel to support as high as 300 Gbps data, the bandwidth density can reach 1 Tbps per millimeter width of data-bus, and the digital pulse modulated carrier can travel more than 5 mm distance on the substrate. I have demonstrated that spoof plasmonic interconnects, comprised of patterned metallic conductors, can simultaneously accommodate electronic TEM mode, which is superior in cross-talk suppression at low-frequencies; and spoof plasmon mode, which is superior at high-frequencies. The research work is divided into two complementary parts: developing a theory for electromagnetic property analysis of spoof plasmon waveguide, and manipulating these properties for high-speed data transfer. Based on the theory developed, I investigated the complex interplay among various figure-of-merits of data transfer in spoof plasmonics, such as bandwidth density, propagation loss, thermal noise, speed of modulation, etc. My developed model predicts that with the availability of 1 THz carrier, the bit-error-rate of spoof plasmon data bus, subject to thermal noise would be $sim10^{-8}$ while the Shannon information capacity of the bus would be $10$ Tbps/mm. The model also predicts that, by proper designing of the modulator, it can be possible to alter the transmission property of the waveguide over one-fifth ($1/5$) of the spoof plasmon band which spans from DC frequency to the frequency of spoof plasmon resonance. To exemplify, if the spoof plasmon resonance is set at $1$ THz, then we can achieve more than $200$ Gbps speed of modulation with a very high extinction ratio, assuming the switching latency of the transistors at our disposal is negligible to the time-resolution of interest. We envision spoof plasmonic interconnects to constitute the next generation communication technology that will be transferring data at hundreds of Gigabit per second (Gbps) speed among different chips on a multi-chip module (MCM) carrier or system-on-chip (SoC) packaging.PHDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/163041/1/srjoy_1.pd

Spoof Surface Plasmon Polaritons Based Antenna and Array by Exciting both Even and Odd Mode Resonances

© 2023 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. This is the accepted manuscript version of a conference paper which has been published in final form at https://doi.org/10.1109/TAP.2023.3335840Spoof surface plasmon polaritons (SSPPs) based antenna and array by exciting both even and odd mode resonances are developed and investigated in this paper. Different from others’ work and for the first time, we use the separated corrugated grooves to achieve the consistent fundamental even and odd mode resonances on the same SSPPs aperture. In this way, the even and odd mode resonances can be operated in the same frequency band. Also for the first time, we introduce the SSPPs into an orthogonal-mode resonated antenna pursuing high isolated radiation. New challenges including the feed methods and impedance matching of two different resonant modes are overcome by introducing the capacitive patch and triangular cuts on the SSPPs. Finally, the SSPPs antenna and array were tested for performance investigation. It is found that in addition to the obtained wide overlapped impedance bandwidth of 14.8%, a very high isolation of 29 dB is achieved in the developed compact antenna element. The couplings between other antenna elements, radiation patterns, gains, and efficiencies of the array are also investigated. Both the measured and simulated results show that SSPPs and the developed antenna can be very appealing in MIMO applications owing to their orthogonal even-odd modes and compact structures.Peer reviewe

Terahertz Spoof Surface Plasmon Polariton Waveguides: A Comprehensive Model with Experimental Verification

Spoof surface plasmon polariton waveguides are perfect candidates to enable novel, miniaturized terahertz integrated systems, which will expedite the next-generation ultra-wideband communications, high-resolution imaging and spectroscopy applications. In this paper, we introduce, for the first time, a model for the effective dielectric constant, which is the most fundamental design parameter, of the terahertz spoof surface plasmon polariton waveguides. To verify the proposed model, we design, fabricate and measure several waveguides with different physical parameters for 0.25 to 0.3THz band. The measurement results show very good agreement with the simulations, having an average and a maximum error of 2.6% and 8.8%, respectively, achieving 10-to-30 times better accuracy than the previous approaches presented in the literature. To the best of our knowledge, this is the first-time investigation of the effective dielectric constant of the tera hertz spoof surface plasmon polariton waveguides, enabling accurate design of any passive component for the terahertz band.Turkish Academy of Sciences (TUBA GEBIP 2015

The engineering way from spoof surface plasmon polaritons to radiations

In recent years, spoof surface plasmon polaritons (SPPs) have been investigated at microwave and THz frequencies for engineering purpose. Due to momentum mismatch, the SPP mode cannot be directly converted from the spatial mode, and vice versa. Stimulating schemes have been developed to transform spatial waveguide modes to SPP modes with high efficiency. On the other hand, the question may arise that, is it possible to transform the propagating SPP waves to directive radiating waves for wireless communication? In view of this, this paper introduces the new-concept antennas based on spoof SPPs at microwave frequencies. Methods of transforming SPP modes to radiating modes are studied, whilst a series of antenna designs are presented and discussed. Feeding networks for antenna arrays using SSPP TLs are also investigated. Most works reviewed in this paper are fulfilled at Southeast University in China

Planar-Goubau-line components for terahertz applications

Terahertz-wave technology has a broad range of applications, including radio astronomy, telecommunications, security, medical applications, pharmaceutical quality control, and biological sensing. However, the sources, detectors, and components are less efficient at this frequency band due to parasitic effects and increased total losses, which hinder the performance of terahertz systems. A common platform for terahertz systems is planar technology, which offers good integration, ease of fabrication, and low cost. However, it also suffers from high losses, which must be minimised to keep the system\u27s performance. A pivotal choice to reduce losses is using power-efficient waveguides, and single-conductor waveguides have shown promisingly high power efficiencies compared to multi-conductor planar waveguides. The planar Goubau line (PGL) is a planar single-conductor waveguide consisting of a metal strip on top of a dielectric substrate which propagates a quasi-transverse magnetic surface wave, similarly to Sommerfeld\u27s wire and the Goubau line, a conducting wire coated with a dielectric layer. Some limitations of the PGL, which complicate the design of components, are the lack of a ground plane and the weak dependence of impedance with the metal strip width of the line.This thesis presents the development of PGL technology and components for terahertz frequencies. It developed design strategies to maximise the power efficiency, using electrically-thin substrates, which drastically drop radiation losses compared to thick substrates. The first PGL calibration standards were developed, which de-embeds the transition needed to excite the propagation mode and sets the calibration plane along the line, allowing the direct characterisation of PGL components. This work also presents several PGL components with a straightforward design procedure, including a stopband filter based on capacitively-coupled λ/2 resonators, an impedance-matched load based on an exponentially-tapered corrugated line, and a power divider based on capacitive-gap coupled lines to a standing wave in the input port. Finally, the PGL was integrated with a microfluidic channel to measure changes in the complex refractive index of a high-loss aqueous sample (water/isopropyl alcohol) as the first step toward a biological sensor

Near-Field Optical Forces: Photonics, Plasmonics and the Casimir Effect

The coupling of macroscopic objects via the optical near-field can generate strong attractive and repulsive forces. Here, I explore the static and dynamic optomechanical interactions that take place in a geometry consisting of a silicon nanomembrane patterned with a square-lattice photonic crystal suspended above a silicon-on-insulator substrate. This geometry supports a hybridized optical mode formed by the coupling of eigenmodes of the membrane and the silicon substrate layer. This system is capable of generating nanometer-scale deflections at low optical powers for membrane-substrate gaps of less than 200 nm due to the presence of an optical cavity created by the photonic crystal that enhances both the optical force and a force that arises from photo-thermal-mechanical properties of the system. Feedback between Brownian motion of the membrane and the optical and photo-thermal forces lead to dynamic interactions that perturb the mechanical frequency and linewidth in a process known as ``back-action.'' The static and dynamic properties of this system are responsible for optical bistability, mechanical cooling and regenerative oscillations under different initial conditions. Furthermore, solid objects separated by a small distance experience the Casimir force, which results from quantum fluctuations of the electromagnetic field (i.e. virtual photons).The Casimir force supplies a strong nonlinear perturbation to membrane motion when the membrane-substrate separation is less than 150 nm. Taken together, the unique properties of this system makes it an intriguing candidate for transduction, accelerometry, and sensing applications.Engineering and Applied Science

Subwavelength Surface Plasmons Based on Novel Structures and Metamaterials

With the rapid development of nanofabrication technology and powerful computational tools over the last decade, nanophotonics has enjoyed tremendous innovation and found wide applications in ultrahigh-speed data transmission, sensitive optical detection, manipulation of ultra-small objects, and visualization of nanoscale patterns. Surface plasmon-based photonics (or plasmonics) merges electronics and photonics at the nanoscale, creating the ability to combine the superior technical advantages of photonics and electronics on the same chip. Plasmonics focuses on the innovation of photonic devices by exploiting the optical property of metals. In particular, the oscillation of free electrons, when properly driven by electromagnetic waves, would form plasmon-polaritons in the vicinity of a metal surface and potentially result in extreme light confinement, which may beat the diffraction limit faced by conventional photonic devices and enable greatly enhanced light-matter interactions at the deep subwavelength scale. The objective of this dissertation is to develop subwavelength or deep subwavelength plasmonic waveguides and explore their integration on conventional dielectric platforms for multiple applications. Three novel structures (or mechanisms) are employed to develop and integrate nanoplasmonic waveguides; each consists of one part of the dissertation. The first part of this dissertation covers the design, fabrication, and demonstration of two-dimensional and three-dimensional metal-insulator-metal plasmonic couplers for mode transformation between photonic and nanoplasmonic domains on the silicon-on-insulator platform. In particular, deep subwavelength plasmonic modes under 100-nm are achieved via end-fire coupling and adiabatic mode transformation at telecom wavelengths. The second part studies metallic gratings as spoof plasmonic waveguides hosting deep subwavelength surface propagation modes. Metallic gratings under different dielectric coatings are numerically investigated for terahertz and gigahertz regions. The third part proposes, explores, and experimentally demonstrates the metametal for super surface wave excitation based on multilayered metal-insulator stacks, where the dispersion of the supported surface modes can be engineered by insulator dopant films in a given metal. The final part discusses the potential applications of active plasmonics for optical sensing, modulation and photovoltaics