S. Papaioannou

Bio: S. Papaioannou is an academic researcher from Aristotle University of Thessaloniki. The author has contributed to research in topics: Wavelength-division multiplexing & Optical switch. The author has an hindex of 13, co-authored 35 publications receiving 575 citations. Previous affiliations of S. Papaioannou include Information Technology Institute.

Next Generation Fiber-Wireless Fronthaul for 5G mmWave Networks

Abstract: mmWave radio, although instrumental for achieving the required 5G capacity KPIs, necessitates the need for a very large number of access points, which places an immense strain on the current network infrastructure. In this article, we try to identify the major challenges that inhibit the design of the Next Generation Fronthaul Interface in two upcoming distinctively highly dense environments: in Urban 5G deployments in metropolitan areas, and in ultra-dense Hotspot scenarios. Second, we propose a novel centralized and converged analog Fiber-Wireless Fronthaul architecture, specifically designed to facilitate mmWave access in the above scenarios. The proposed architecture leverages optical transceivers, optical add/drop multiplexers and optical beamforming integrated photonics towards a Digital Signal Processing analog fronthaul. The functional administration of the fronthaul infrastructure is achieved by means of a packetized Medium Transparent Dynamic Bandwidth Allocation protocol. Preliminary results show that the protocol can facilitate Gb/s-enabled data transport while abiding to the 5G low-latency KPIs in various network traffic conditions.

Active plasmonics in WDM traffic switching applications

Abstract: With metal stripes being intrinsic components of plasmonic waveguides, plasmonics provides a “naturally” energy-efficient platform for merging broadband optical links with intelligent electronic processing, instigating a great promise for low-power and small-footprint active functional circuitry. The first active Dielectric-Loaded Surface Plasmon Polariton (DLSPP) thermo-optic (TO) switches with successful performance in single-channel 10 Gb/s data traffic environments have led the inroad towards bringing low-power active plasmonics in practical traffic applications. In this article, we introduce active plasmonics into Wavelength Division Multiplexed (WDM) switching applications, using the smallest TO DLSPP-based Mach-Zehnder interferometric switch reported so far and showing its successful performance in 4×10 Gb/s low-power and fast switching operation. The demonstration of the WDM-enabling characteristics of active plasmonic circuits with an ultra-low power × response time product represents a crucial milestone in the development of active plasmonics towards real telecom and datacom applications, where low-energy and fast TO operation with small-size circuitry is targeted.

Dielectric‐loaded plasmonic waveguide components: Going practical

Abstract: Surface plasmon propagating modes supported by metal/dielectric interfaces in various configurations can be used for radiation guiding similarly to conventional dielectric waveguides. Plasmonic waveguides offer two attractive features: subdiffraction mode confinement and the presence of conducting elements at the mode-field maximum. The first feature can be exploited to realize ultrahigh density of nanophotonics components, whereas the second feature enables the development of dynamic components controlling the plasmon propagation with ultralow signals, minimizing heat dissipation in switching elements. While the first feature is yet to be brought close to the domain of practical applications because of high propagation losses, the second one is already being investigated for bringing down power requirements in optical communication systems. In this review, the latest application-oriented research on radiation modulation and routing using thermo-optic dielectric-loaded plasmonic waveguide components integrated with silicon-based photonic waveguides is overviewed. Their employment under conditions of real telecommunications is addressed, highlighting challenges and perspectives.

A 5G mmWave Fiber-Wireless IFoF Analog Mobile Fronthaul Link With up to 24-Gb/s Multiband Wireless Capacity

Abstract: We experimentally demonstrate a multiband intermediate frequency-over-fiber/mmWave (IFoF/mmWave) fiber/wireless mobile fronthaul link for gigabit capacity over the unlicensed V-band (57–64 GHz). Digital synthesis of the multiband radio waveforms is performed at the baseband unit using digital subcarrier multiplexing technique, whereas digital predistortion is exploited to cope with the analog IFoF channel impairments without any further baseband processing at the digital-free remote radio head. Commercial optoelectronic components and analog V-band radio and antenna equipment for 7-km fiber and 5-m wireless transmission are employed to successfully demonstrate both uplink and downlink connectivity. An aggregate capacity up to 24 Gb/s was demonstrated with a 6-band 1 Gbaud 16-QAM on a 7.2-GHz analog bandwidth over the combined fiber/wireless channel showing error vector magnitude (EVM) values below the 3GPP requirements (<12.5%) for 5G systems. Multiformat assignment on each subcarrier was also realized by using M-PSK and 16-QAM schemes to achieve 18-Gb/s connectivity for both uplink and downlink, while demonstrating flexible resource allocation capabilities. By replacing the stand-alone optical modulator with an InP-based externally modulated laser chip for the implementation of the IFoF transmitter, a 16-Gb/s aggregate capacity was showcased on a 7-km fiber link and 5-m wireless channel with a 4-band 16-QAM encoded at 1 Gbaud. Successful operation with robust EVM performance was demonstrated using also the 6-band scheme of 1 Gbaud QPSK bands.

A 320 Gb/s-Throughput Capable 2 $\,\times\,$ 2 Silicon-Plasmonic Router Architecture for Optical Interconnects

Abstract: We demonstrate a 2 × 2 silicon-plasmonic router architecture with 320 Gb/s throughput capabilities for optical interconnect applications The proposed router platform relies on a novel dual-ring Dielectric-Loaded Surface Plasmon Polariton (DLSPP) 2 × 2 switch heterointegrated on a Silicon-on-Insulator (SOI) photonic motherboard that is responsible for traffic multiplexing and header processing functionalities We present experimental results of a Poly-methyl-methacrylate (PMMA)-loaded dual-resonator DLSPP waveguide structure that uses two racetrack resonators of 55 μm radius and 4 μ m-long straight sections and operates as a passive add/drop filtering element We derive its frequency-domain transfer function, confirm its add/drop experimental spectral response, and proceed to a circuit-level model for dual-ring DLSPP designs supporting 2 × 2 thermo-optic switch operation The validity of our circuit-level modeled 2 × 2 thermo-optic switch is verified by means of respective full vectorial three-dimensional Finite Element Method (3D-FEM) simulations The router setup is completed by means of two 4 × 1 SOI multiplexing circuits, each one employing four cascaded second order micro-ring configurations with 100 GHz spaced resonances Successful interconnection between the DLSPP switching matrix and the SOI circuitry is performed through a butt-coupling design that, as shown via 3D-FEM analysis, allows for small coupling losses of as low as 26 dB The final router architecture is evaluated through a co-operative simulation environment, demonstrating successful 2 × 2 routing for two incoming 4-wavelength Non-Return-to-Zero (NRZ) optical packet streams with 40 Gb/s line-rates

Active Plasmonics: Principles, Structures, and Applications

Abstract: Active plasmonics is a burgeoning and challenging subfield of plasmonics. It exploits the active control of surface plasmon resonance. In this review, a first-ever in-depth description of the theoretical relationship between surface plasmon resonance and its affecting factors, which forms the basis for active plasmon control, will be presented. Three categories of active plasmonic structures, consisting of plasmonic structures in tunable dielectric surroundings, plasmonic structures with tunable gap distances, and self-tunable plasmonic structures, will be proposed in terms of the modulation mechanism. The recent advances and current challenges for these three categories of active plasmonic structures will be discussed in detail. The flourishing development of active plasmonic structures opens access to new application fields. A significant part of this review will be devoted to the applications of active plasmonic structures in plasmonic sensing, tunable surface-enhanced Raman scattering, active plasmoni...

Attosecond metrology: from electron capture to future signal processing

Abstract: The accurate measurement of time lies at the heart of experimental science, and is relevant to everyday life. Extending chronoscopy to ever shorter timescales has been the key to gaining real-time insights into microscopic phenomena, ranging from vital biological processes to the dynamics underlying high technologies. The generation of isolated attosecond pulses in 2001 allowed the fastest of all motions outside the nucleus — electron dynamics in atomic systems — to be captured. Attosecond metrology has provided access to several hitherto immeasurably fast electron phenomena in atoms, molecules and solids. The fundamental importance of electron processes for the physical and life sciences, technology and medicine has rendered the young field of attosecond science one of the most dynamically expanding research fields of the new millennium. Here, we review the basic concepts underlying attosecond measurement and control techniques. Among their many potential applications, we focus on the exploration of the fundamental speed limit of electronic signal processing. This endeavour relies on ultimate-speed electron metrology, as provided by attosecond technology. This article reviews the basic concepts underlying attosecond measurement and control techniques. Emphasis is given to exploring the fundamental speed limit of electronic signal processing that employs ultimate-speed electron metrology provided by attosecond technology.

Nanoscale conducting oxide PlasMOStor.

Abstract: We experimentally demonstrate an ultracompact PlasMOStor, a plasmon slot waveguide field-effect modulator based on a transparent conducting oxide active region. By electrically modulating the conducting oxide material deposited into the gaps of highly confined plasmonic slot waveguides, we demonstrate field-effect dynamics giving rise to modulation with high dynamic range (2.71 dB/μm) and low waveguide loss (∼0.45 dB/μm). The large modulation strength is due to the large change in complex dielectric function when the signal wavelength approaches the surface plasmon resonance in the voltage-tuned conducting oxide accumulation layer. The results provide insight about the design of ultracompact, nanoscale modulators for future integrated nanophotonic circuits.

Applications of Plasmon-Enhanced Nanocatalysis to Organic Transformations.

Abstract: Localized surface plasmon resonance (LSPR) is a physical phenomenon exhibited by nanoparticles of metals including coinage metals, alkali metals, aluminum, and some semiconductors which translates into electromagnetic, thermal, and chemical properties. In the past decade, LSPR has been taken advantage of in the context of catalysis. While plasmonic nanoparticles (PNPs) have been successfully applied toward enhancing catalysis of inorganic reactions such as water splitting, they have also demonstrated exciting performance in the catalysis of organic transformations with potential applications in synthesis of molecules from commodity to pharmaceutical compounds. The advantages of this approach include improved selectivity, enhanced reaction rates, and milder reaction conditions. This review provides the basics of LSPR theory, details the mechanisms at play in plasmon-enhanced nanocatalysis, sheds light onto such nanocatalyst design, and finally systematically presents the breadth of organic reactions hence catalyzed.

Radiation guiding with surface plasmon polaritons

Abstract: Surface plasmon polaritons (SPPs) are electromagnetic (EM) modes propagating along metal‐dielectric interfaces, in which surface collective excitations of free electrons in the metal are coupled to evanescent EM fields in the dielectric. Various SPP modes can be supported by flat and curved, single and multiple surfaces, exhibiting remarkable properties, including the possibility of concentrating EM fields beyond the diffraction limit, i.e. on the nanoscale, while enhancing local field strengths by several orders of magnitude. This unique feature of SPP modes, along with the ever-increasing demands for miniaturization of photonic components and circuits, generates an exponentially growing interest in SPP-mediated radiation guiding and SPP-based waveguide components. Here we review the current status of this rapidly developing field, starting with a brief presentation of the main planar SPP modes along with the techniques employed for their excitation and manipulation by sets of nanoparticles. We then describe in detail various SPP-based waveguide configurations that ensure two-dimensional mode confinement in the plane perpendicular to the propagation direction and compare their characteristics. Excitation of SPP waveguide modes and recent progress in the development of SPP-based waveguide components are also discussed, concluding with our outlook on challenges and possible future developments in this field. (Some figures may appear in colour only in the online journal) This article was invited by Horst-Guenter Rubahn.