Mid Sweden University

This paper reports the design and numerical results of three new extremely compact and efficient flat-top band-pass plasmonic filters operating in the near-infrared region. The proposed structures are realized in metal–insulator-metal plasmonic waveguides based on stub, tilted T-junction and right-angle trapezoid configurations. A built-in parameterized genetic algorithm is applied to maximize the transmission efficiency, while at the same time contributing to shrinking down the size of the device structures. It is shown that the tunability of the optical filters can be realized by modulating their structural parameters to gain control over the band-pass filtering wavelengths. Numerical calculations are conducted based on the finite element method of CST Microwave Studio and demonstrate that the suggested ultra-compact plasmonic waveguide filters offer wide bandwidths of more than 270 nm, 424 nm, and 289 nm, with transmission efficiencies of higher than 80%, 74.2%, and 74.3%, respectively. The sizes of the proposed wavelength filters are 490 nm × 575 nm, 350 nm × 180 nm, and 420 nm × 150 nm, respectively, which make them attractive candidates for applications in high density photonic integrated circuits (PICs). As a result, because of the promising characteristics of the proposed topologies such as their high efficiency, compact size, tunability, and simple structure they may find applications in on-chip integration, laser technology, and multi-photon fluorescence. 

This paper presents the design and numerical investigation of a novel, tunable, and highly efficient metal–insulator-metal (MIM) plasmonic device specifically designed for near-infrared (NIR) applications. The device leverages strategically placed stub resonators within a MIM waveguide. We introduce two small perturbations, a triangle and a rectangle, to achieve remarkable functional versatility. Comprehensive numerical analysis, employing the finite element method (FEM) and validated by the transmission line method (TLM), demonstrates the working principle and excellent agreement between the approaches. Our simulation-driven approach, utilizing a Genetic Algorithm (GA) for accelerated optimization, was crucial in achieving performance levels difficult or costly to reach through purely experimental methods. The GA enabled efficient exploration of a vast parameter space, iterative refinement of device configurations, and fine-tuning of geometric characteristics. This meticulous optimization allows us to control complex interactions within the simulated structure. The proposed device offers diverse functionalities based on adjusted geometrical parameters, including: A. Flat-top band-pass filtering: Achieving a maximum transmission efficiency of 95.8 % within a compact footprint of 420 nm × 540 nm. B. Dual-band band-pass filtering: Maintaining a high transmission efficiency of 88.4 % within a slightly larger size of 450 nm × 540 nm. C. Triple-band notch filtering: Exhibiting minimum transmission (below 1 %) at specific resonance wavelengths for targeted signal suppression. D. Plasmon-induced transparency (PIT) effect: Offering potential applications in various optical functionalities. And, E. Perfect absorption: Achieving a maximum absorption efficiency of 99.62 %, paving the way for efficient light harvesting and manipulation. This multifunctional plasmonic device excels in its combination of compactness, tunability, and diverse NIR functionalities. It holds promise for miniaturized optical components, integrated photonic circuits, and advanced light-matter interactions. Our findings contribute significantly to the advancement of compact, efficient, and readily manufacturable photonic technologies.

This paper presents design and numerical investigations of an ultra-compact, and highly-efficient plasmonic absorber based on metal–insulator–metal waveguides. The proposed device offers multiple narrow-band absorption at visible and near-infrared wavelengths with peak absorbance between 81 and 100%. The finite element method has been used to simulate the proposed structure. The simulation results show that the resonance wavelengths can be easily modulated by tuning the coupling distances between the input and output ports and the triangular resonators. To find the optimized size of the proposed structure, maximize its efficiency, and attain narrow-band resonances, a parameterized genetic algorithm has been used. Taking into account the obtained notable specifications of the proposed structure, it can contribute to the development of miniaturized and efficient optical components for photonic integrated circuits. 

This paper presents the design and numerical investigation of tunable, ultra-compact, and highly-efficient plasmonic filters based on stepped impedance resonators (SIRs). The proposed devices are realized in metal–insulator-metal (MIM) plasmonic waveguide systems and exhibit more degrees of freedom and high flexibility to design resonator-based devices, thanks to the SIRs. The principle of conventional SIRs is discussed in terms of equivalent circuit model and characteristic impedance. Among the three proposed plasmonic filters, one of them acts as a short-wavelength, while the other two nanostructures work as long-wavelength cut-off filters at near-infrared region (NIR) and telecom wavelengths. Simulation results are carried out by a finite element method (FEM)-based solver and indicate that the cut-off wavelengths of the proposed resonators found to be at 1187 nm, 1265 nm, and 999 nm, respectively, can be easily tuned by modulating their structural parameters. In addition to the mentioned remarkable properties of the designed structures including the size which are found to be 500 nm × 310 nm, 350 nm × 285 nm, and 210 nm × 195 nm, respectively, the simple structures of the proposed topologies facilitate their fabrication process. Therefore, the suggested devices can contribute to the development of miniaturized, tunable, and efficient optical components for photonic integrated circuits (PICs) applications and in optical wireless communication systems. 

Industrial innovation is mostly driven by miniaturization. As a result of remarkable technological advancements in the fields of equipment, materials and production processes, transistor, the fundamental active component in conventional electronics, has shrunk in size. Semiconductor technology is unique in that all performance metrics are enhanced, while at the same time unit prices are reduced. Moore’s Law, which predicts that the number of components per chip will double every two years, was established in 1965, and the industry has been able to keep up with this prophetic prognosis since. Thermal management, on the other hand, has become a key limiting factor for current electronic circuits and is set to put a stop to Moore’s Law. Given the fact that complementary metal oxide semiconductor (CMOS) scaling is reaching fundamental limits, there are several new alternative processing devices and architectures that have been investigated for both traditional integrated circuit (IC) technologies and novel technologies, including new technologies aimed at contributing to advances in scaling progress and cost reductions in manufacturing operations in the coming decades. These factors will encourage the development of new information processing and memory systems, new technologies for integrating numerous features heterogeneously and new system architectural design layouts, among other things. Energy efficiency is advantageous from a sustainability perspective and for consumer electronics, for which fewer power-hungry components mean longer times between charges and smaller batteries. The creation of novel chip-scale tools that can aid in the transfer of information across optical frequencies and microscale photonics between nanoscale electronic devices is now a possibility. Bridging this technological gap may be achieved by plasmonics. The incorporation of plasmonic, photonic and electrical components on a single chip may lead to a number of innovative breakthroughs. Photonic integrated circuits (PICs) enable the realization of ultra-small, high-efficiency, ultra-responsive and CMOS-compatible devices that can be used in applications ranging from optical wireless communication systems (6G and beyond) and supercomputers to health and energy.

This thesis provides a platform from which to design nanoplasmonic devices while facilitating high-transmission and/or absorption efficiency, miniaturized size and the use of near-infrared (NIR) wavelengths for telecom applications. With a significant amount of Internet traffic transmitted optically, communication systems are further tightening the requirements for the development of new optical devices. Several new device structures based on the metal-insulator-metal (MIM) plasmonic waveguide are proposed and investigated using performance metrics. The transmission line theory (TLM) from microwave circuit theory and coupled mode theory (CMT) is studied and employed in the design process of the nanostructures, in particular to address the losses in plasmonic-based devices, which has been the major factor hampering their widespread usage in communication systems. By taking advantage of well-established microwave circuit theory (through new design that paves the way for mitigating these losses and enabling efficient transmission of power flow in the optical devices), we have suggested a number of high-transmission efficiency nanodevices that offer highly competitive performance compared with other platforms. As a result, a promising future for plasmonic technology, which would enable design and fabrication of multipurpose and multifunctional optical devices that are efficient in terms of losses, footprint and capability of integrating active devices, is anticipated.

Branschinnovation drivs främst av miniatyrisering. Som ett resultat av anmärkningsvärda tekniska framsteg inom områdena utrustning, material och produktionsprocesser kunde transistoren, den grundläggande aktiva komponenten i samtida elektronik, krympa i storlek. Halvledarteknik är unik genom att alla prestandamått förbättras, samtidigt som enhetspriserna sänks. Moores Lag, som förutspår att antalet komponenter per chip skulle fördubblas vartannat år, inrättades 1965, och branschen har kunnat hålla jämna steg med den profetiska prognosen sedan dess. Termisk hantering, å andra sidan, har blivit en viktig begränsande faktor för nuvarande elektroniska kretsar, och är inställd på att sätta stopp för Moores Lag. Med tanke på att CMOS-skalningen (Complementary Metal Oxide Semiconductor) når grundläggande gränser finns det flera nya alternativa bearbetningsanordningar och arkitekturer som har undersökts för både traditionell integrerad kretsteknik och ny teknik. Ny teknik som syftar till att bidra till framsteg i skalningen av framsteg och kostnadsminskningar i tillverkningsverksamheten under de kommande årtiondena. Dessa faktorer uppmuntrar utvecklingen av nya informationsbehandlings- och minnessystem, ny teknik för att integrera många funktioner heterogent och nya systemarkitekturdesignlayouter, bland annat. Energieffektivitet är fördelaktigt ur ett hållbarhetsperspektiv och för hemelektronik, där färre krafthungriga elektroniker innebär längre tid mellan laddningar och stimulerar för ett mindre energilagringssystem ombord. Skapandet av nya chip-scale verktyg som kan bidra till överföring av information över optiska frekvenser och mikroskala fotonik mellan elektroniska enheter i nanoskala är nu en möjlighet. Överbrygga denna tekniska klyfta kan uppnås av plasmonics. Införlivandet av plasmoniska, fotoniska och elektriska komponenter på ett enda chip kan leda till ett antal innovativa genombrott. Fotoniska integrerade kretsar (PIC-enheter) möjliggör förverkligande av ultrasmå, högeffektiva, ultraresponsiva och CMOS-kompatibla enheter som kan användas i applikationer som sträcker sig från optiska trådlösa kommunikationssystem (6G och därefter), superdatorer till hälso- och energiändamål.

Denna avhandling ger en plattform för att designa nanoplasmoniska enheter samtidigt som den innehåller hög överförings- och eller absorptionseffektivitet, miniatyriserad storlek och vid önskade våglängder av nära infraröd (NIR) för telekomapplikationer. Med den betydande mängden Internettrafik som överförs optiskt skärper kommunikationssystemen ytterligare kraven för utveckling av nya optiska enheter. Flera nya enhetsstrukturer baserade på metall-isolator-metall (MIM) plasmonisk vågledare föreslås och numeriskt undersöks. Överföringslinjeteorin (TLM) från mikrovågskretsteori och kombinationslägesteori (CMT) studeras och används i nanostrukturerna. För att ta itu med de förluster i plasmonbaserade enheter som har varit den viktigaste parametern som hindrade deras utbredda användning i kommunikationssystem, genom att dra nytta av den väletablerade mikrovågskretsteorin (genom ny design som banar väg för att mildra förlusterna och möjliggöra effektiv överföring av kraftflödet i den optiska enheten).  Vi har framgångsrikt föreslagit ett antal nanodevices med hög överföringseffektivitet som erbjuder en mycket konkurrenskraftig prestanda jämfört med andra plattformar. Som ett resultat förväntar vi oss en lovande framtid för plasmonisk teknik som skulle möjliggöra design och tillverkning av mångsidiga och multifunktionella optiska enheter som är effektiva när det gäller förluster, fotavtryck och förmåga att integrera aktiva enheter.

We report design and simulation results of a high-efficiency long-wavelength cut-off filter realized by stepped impedance resonators. Moreover, numerical results confirm by modulating the length of resonator, cut-off wavelength can be easily tuned.

This paper reports design and numerical results of an ultra-compact, efficient and tunable plasmonic band-stop filter based on a metal-insulator-metal waveguide at optical channels. Furthermore, a wide-bandgap can be easily achieved by adjusting the width of the of the stub resonator.

A miniaturized and efficient tunable wide flat-top band-pass filter at NIR is proposed in a MIM plasmonic waveguide. Furthermore, numerical results illustrate that tunability is readily attained by varying length of right-angle trapezoid resonator.

A highly efficient and compact wide flat-top band-pass filter at NIR is realized in a MIM plasmonic waveguide.Besides, simulation results reveal that through tuning the length of resonators, a broadband band-pass transmission can beeasily achieved.

We report the design and numerical results of a miniaturized and efficient plasmonic cut-off filter that is based on stepped impedance resonators and operates at telecom wavelengths.