Novel Surface Plasmon Polariton Waveguides with Enhanced Field Confinement for Microwave-Frequency Ultra-Wideband Bandpass Filters

© 2013 IEEE. In this paper, a novel planar waveguide based on spoof surface plasmon polaritons (SSPPs) using fish-bone corrugated slot structure is first proposed in the microwave region. Low-dispersion band can be realized by such structure with tight field confinement of SSPPs, resulting in size miniaturization of the proposed waveguide. The high frequency stopband of the proposed ultra-wideband bandpass filter (BPF) is created by using this proposed waveguide, while the low frequency stopband is properly designed through introducing the microstrip-to-slotline transition. The 2-D E-fields distribution, surface current flow, and energy flow patterns are all calculated and illustrated to demonstrate the electromagnetic (EM) characteristics of the proposed ultra-wideband BPF. The BPF tuning characteristics is explored to provide a guideline for facilitating the design process. To validate the predicted performance, the proposed filter is finally designed, fabricated, and measured. Measured results illustrate high performance of the filter, in which the reflection coefficient is better than -10 dB from 2.1 to 8 GHz with the smallest insertion loss of 0.37 dB at 4.9 GHz, showing good agreement with numerical simulations. The proposed surface plasmon polariton waveguides are believed to be significantly promising for further developing plasmonic functional devices and integrated 2-D circuits with enhanced confinement of SSPPs in microwave and even terahertz bands

Design, Analysis and Characterisation of Spoof Surface Plasmon Polaritons based Wideband Bandpass Filter at Microwave Frequency

This paper presents the wideband bandpass filter (BPF) in the microwave frequency domain. The realisation approach is based on spoof surface plasmon polaritons (SSPPs) phenomenon using plasmonic metamaterial. A novel unit cell is designed for filter design using an LC resonator concept. Then SSPPs BPF is realised using an optimised mode converter and five unit cells. This paper includes a brief design detail of the proposed novel unit cell. The passband of BPF is achieved at approximately 1.20 - 5.80 GHz, 3dB bandwidth is tentatively 4.60 GHz and the insertion loss is less than 2 dB approximately over the passband. The overall dimension of fabricated filter is (90 x 45) mm. A basic schematic of transmission line representation is also proposed to evaluate the BPF structure

Design, Modeling and Numerical Analysis of Microwave and Optical Devices: The Multi-band Patch Antenna, Ultra Wideband Ring Filter and Plasmonic Waveguide Coupler

In this dissertation, three devices are studied and devised for the applications in microwave and optical communication: (1) Multiband Patch Antenna, (2) Ultra-Wideband Band Pass Ring Filter and (3) Plasmonic Waveguide Coupler with High Coupling Efficiency. First, the idea of a simple frequency reconfigurable patch antenna that operates at multiband from 2 GHz to 4.5 GHz is presented; by changing the position of the microstrip connecting elements on the antenna patches, the operating frequency will shift with fixed radiation patterns, which can be utilized in MIMO (Multiple IN Multiple Out) wireless data transmission. Next, a compact ultra-wideband (UWB) single-ring bandpass filter of 8GHz bandwidth with sideband and harmonics suppression achieved by forced boundary condition and step impedance filter is proposed. This approach provides a simple way for the design of ultra-wideband filters. Based on the transmission spectrum, it is known that the group delay variation in the pass-band is smaller than 0.3 ns, which indicates the proposed structure is very suitable for real applications. Finally, a short partially corrugated tapered waveguide for silicon-based micro-slab waveguide to plasmonic nano-gap waveguide mode conversion at the optical communication frequency is investigated. The structure is designed to achieve mode matching between the silicon slabs and plasmonic waveguides. High coupling efficiencies up to 87%~98% are demonstrated numerically. The results show that the corrugated structure will be helpful for realizing full on-chip silicon plasmonic devices

New opportunities for integrated microwave photonics

Recent advances in photonic integration have propelled microwave photonic technologies to new heights. The ability to interface hybrid material platforms to enhance light-matter interactions has led to the developments of ultra-small and high-bandwidth electro-optic modulators, frequency synthesizers with the lowest noise, and chip signal processors with orders-of-magnitude enhanced spectral resolution. On the other hand, the maturity of high-volume semiconductor processing has finally enabled the complete integration of light sources, modulators, and detectors in a single microwave photonic processor chip and has ushered the creation of a complex signal processor with multi-functionality and reconfigurability similar to their electronic counterparts. Here we review these recent advances and discuss the impact of these new frontiers for short and long term applications in communications and information processing. We also take a look at the future perspectives in the intersection of integrated microwave photonics with other fields including quantum and neuromorphic photonics

Active and Fast Tunable Plasmonic Metamaterials

Active and Fast Tunable Plasmonic Metamaterials is a research development that has contributed to studying the interaction between light and matter, specifically focusing on the interaction between the electromagnetic field and free electrons in metals. This interaction can be stimulated by the electric component of light, leading to collective oscillations. In the field of nanotechnology, these phenomena have garnered significant interest due to their ability to enable the transmission of both optical signals and electric currents through the same thin metal structure. This presents an opportunity to connect the combined advantages of photonics and electronics within a single platform. This innovation gives rise to a new subfield of photonics known as plasmonic metamaterials.Plasmonic metamaterials are artificial engineering materials whose optical properties can be engineered to generate the desired response to an incident electromagnetic wave. They consist of subwavelength-scale structures which can be understood as the atoms in conventional materials. The collective response of a randomly or periodically ordered ensemble of such meta-atoms defines the properties of the metamaterials, which can be described in terms of parameters such as permittivity, permeability, refractive index, and impedance. At the interface between noble metal particles and dielectric media, collective oscillations of the free electrons in the metal particles can be resonantly excited, known as plasmon resonances. This work considered two plasmon resonances: localised surface plasmon resonances (LSPRs) and propagating surface plasmon polaritons (SPPs).The investigated plasmonic metamaterials, designed with specific structures, were considered for use in various applications, including telecommunications, information processing, sensing, industry, lighting, photovoltaic, metrology, and healthcare. The sample structures are manufactured using metal and dielectric materials as artificial composite materials. It can be used in the electromagnetic spectrum's visible and near-infrared wavelength range. Results obtained proved that artificial composite material can produce a thermal coherent emission at the mid-infrared wavelength range and enable active and fast-tunable optoelectronic devices. Therefore, this work focused on the integrated thermal infrared light source platforms for various applications such as thermal analysis, imaging, security, biosensing, and medical diagnosis. Enabled by Kirchhoff's law of thermal radiation, this work combined the concepts of material absorption with material emission. Hence, the results obtained proved that this approach enhances the overall performance of the active and fast-tunable plasmonic metamaterial in terms of with effortless and fast tunability. This work further considers the narrow line width of the coherent thermal emission, tunable emission, and angular tunable emission at the mid-infrared, which are achieved through plasmonic stacked grating structure (PSGs) and plasmonic infrared absorber structure (PIRAs).Three-dimensional (3D) plasmonic stacked gratings (PSGs) was used to create a tunable plasmonic metamaterial at optical wavelengths ranging from 3 m to 6 m, and from 6m to 9 m. These PSGs are made of a metallic grating with corrugations caused by narrow air openings, followed by a Bragg grating (BG). Additionally, this work demonstrated a thermal radiation source customised for the mid-infrared wavelength range of 3 μm to 5 μm. This source exhibits intriguing characteristics such as high emissivity, narrowband spectra, and sharp angular response capabilities. The proposed thermal emitter consists of a two-dimensional (2D) metallic grating on top of a one-dimensional dielectric BG.Results obtained presented a plasmonic infrared absorber (PIRA) graphene nanostructure designed for a wavelength range of 3 to 14 μm. It was observed and concluded that this wavelength range offers excellent opportunities for detection, especially when targeting gas molecules in the infrared atmospheric windows. The design framework is based on active plasmon control for subwavelength-scale infrared absorbers within the mid-infrared range of the electromagnetic spectrum. Furthermore, this design is useful for applications such as infrared microbolometers, infrared photodetectors, and photovoltaic cells.Finally, the observation and conclusion drawn for the sample of nanostructure used in this work, which consists of an artificial composite arrangement with plasmonic material, can contribute to a highly efficient mid-infrared light source with low power consumption, fast response emissions, and is a cost-effective structure

Plasmonics and metamaterials at terahertz frequencies

The research presented in this manuscript falls under the framework of metamaterials and plasmonics. It is mainly focused on applications at terahertz (THz) frequencies, a spectral band located between microwaves and infrared. Metamaterials are advanced materials able to synthesize electromagnetic properties hardly found in natural materials by means of engineering their meta-atoms. Metallic inclusions are commonly used in metamaterials design. At low frequency bands such as microwaves and millimeter-waves, metals behave fundamentally differently than at infrared and optics. Plasmonics sets the theory of the interaction processes between electromagnetic radiation and conduction electrons of metals at such high frequencies. The objective of this thesis is to devise, design, analyze and, whenever possible, experimentally realize and measure new metamaterials and plasmonics devices for free-space quasi-optical applications. Particularly, field concentrators in the form of advanced lenses and nanoantennas as well as advanced polarizing devices are targeted. The contributions presented here start from the specific theory of the field and the results are supported by numerical simulations, analytical calculations and/or measurements of real prototypes.Programa Oficial de Doctorado en Tecnologías de las Comunicaciones (RD 1393/2007)Komunikazioen Teknologietako Doktoretza Programa Ofiziala (ED 1393/2007

The 2019 surface acoustic waves roadmap

Today, surface acoustic waves (SAWs) and bulk acoustic waves are already two of the very few phononic technologies of industrial relevance and can been found in a myriad of devices employing these nanoscale earthquakes on a chip. Acoustic radio frequency filters, for instance, are integral parts of wireless devices. SAWs in particular find applications in life sciences and microfluidics for sensing and mixing of tiny amounts of liquids. In addition to this continuously growing number of applications, SAWs are ideally suited to probe and control elementary excitations in condensed matter at the limit of single quantum excitations. Even collective excitations, classical or quantum are nowadays coherently interfaced by SAWs. This wide, highly diverse, interdisciplinary and continuously expanding spectrum literally unites advanced sensing and manipulation applications. Remarkably, SAW technology is inherently multiscale and spans from single atomic or nanoscopic units up even to the millimeter scale. The aim of this Roadmap is to present a snapshot of the present state of surface acoustic wave science and technology in 2019 and provide an opinion on the challenges and opportunities that the future holds from a group of renown experts, covering the interdisciplinary key areas, ranging from fundamental quantum effects to practical applications of acoustic devices in life science

Plasmonic waveguides and nano-antennas for optical communications

The field of plasmonics has received great attention during the past years. Plasmonic devices are characterized by their small electrical size which enabled researchers to overcome the challenge of the size mismatch between the bulky photonic devices and the small electronic circuits. Plasmonic metals are characterized by their lossy dielectric nature which is different from the highly conductive classical metals. Consequently, the design of plasmonic devices necessitates upgrading the existing solvers to take into consideration their material properties at the optical frequency range. In this thesis, a plasmonic transmission line mode solver is developed in which the propagation characteristics of plasmonic transmission lines/waveguides are calculated. More specifically, the solver calculates the propagation constant, losses, and mode profile(s) of the propagating mode(s). The transmission lines can have any topology and are assumed to be placed within a stack of flat layers. The solver is developed using the Method of Moments technique which is characterized by its tremendously decreased number of unknowns compared to the finite element/difference methods leading to much faster calculation time. The solver is tested on several plasmonic transmission lines of various topologies, number of metallic strips and/or surrounding media. These transmission lines include rectangular strip, circular strip, triangular strip, U-shaped strip, horizontally coupled strips, and vertically coupled strips. The obtained results are compared with those calculated by the commercial tool “CSTâ€. Very good agreement between both solvers is achieved. The second line presented within this thesis is concerned with the design of plasmonic wire-grid nano-antenna arrays. The basic element of this array is a nano-rod, whose propagation characteristics are first obtained using the developed solver. The arrays are then optimized using “CSTâ€. Within the context of this thesis, three nano-antenna arrays are proposed: a five-element wire-grid array, an eleven-element wire-grid array, and a novel circularly polarized wire-grid array. All of these arrays have high directivity and are suitable for inter-/intra-chip optical communication, where they replace the losing transmission lines