Micro/nano-scale optical network: A new challenge toward next generation

This presentation discourses on a newly emerging frontier technology called VLSI (very large scale integrated) photonics. It is a new field of optical circuit or optical network technology rapidly evolving in micro/nano-scale yet to complete the unfinished information revolution brought forth by the megascale optical fiber-based global network. It discusses the science and engineering of micro/nano-photonics and integration that can lead to VLSI photonic circuits and networks of generic and application-specific nature. The world in the 21st century is facing many new kinds of problems, including increasing demand for big data, higher information capacity, increasing population, increasing cost of energy, shortage of food and natural resources, environmental problems, global warming, increasing medical and health problems, and increasing demand for well living. Electron-based technology in the 20th century is beginning to show many limitations in the face of these and other rising problems. Photon-based technology, on the other hand, is showing many new promises that can lead to solutions to many of thes problems that electrons alone cannot. Compact, high-speed, light-weight, and low-powered optical and photonic micro/nano-systems using nano-wires, micro/nano-structures, plasmonics, and metamaterials, show possibilities of new properties and functions that can provide new solutions for the rising problems, that can address green and sustainable IT/BT/NT applications in the 21st century. The new optical systems consist of arrays of micro/nano-scale optical wires, circuits and devices on chips or on modular boards to perform the functions of sensing, switching, modulating, processing, transporting, routing, and distributing optical signals. The optical components include micro/nano-scale light sources, waveguides, detectors, switches, modulators, sensors, couplers, filters, resonators, photonic crystal devices, plasmonic devices, and quantum structures, made of polymer, silicon and other semiconductor micro/nano-materials. We discuss scientific and technological issues and challenges for the miniaturization and integration of micro/nano-scale photonic materials, devices, circuits, and networks for ultra-small and high-density integration and application. It includes new physics, theories, materials, designs, and structures. New perspectives and visions will be discussed along with the historical perspectives of the electrical technology. Recent progresses and examples will be presented.

This paper presents an overview of our work on the theory, design, fabrication, and integration of micro/nano-scale optical devices as applicable for all-optical generic and application-specific VLSI photonic integration. The micro/nano-optical devices are designed to perform the functions of collecting, storing, transporting, processing, switching, routing, and distributing optical signals on chips. The integrated optical components include micro/nano-scale optical waveguides, switches, modulators, sensors, directional couplers, multi-mode interference devices, micro-ring resonators, photonic crystal devices, and plasmonic devices made of polymer, silicon and semiconductor materials. The paper discusses scientific and engineering issues of miniaturizing and integrating micro/nano-scale photonic devices of small and ultra-small dimensions to a very large scale integration density as applicable for specific functions. Scientific and engineering issues are examined and examples of progresses are presented.

Extending the researches on wavelength switched optical networks (WSON), efficient integration of the novel optical packet switching network and wavelength switching-based optical circuit switching network technologies which offers both best-effort packet delivery and QoS guaranteed lightpath services has been being studied. In addition, researches on the optical-layer transparent data processing, such as all-optical wavelength multicasting, all-optical 3R regeneration, etc, are conducted simultaneously. It is believed that future innovative optical network services (INSes) would be built on these novel future-proof technologies, and foster colorful applications in the new generation networks. Before the wide applications of INS in different fields, there would be a foreseeable strong requirement for INS firstly posed by pioneer grid applications, e.g., e-science, e-government, and e-banking, etc, which would require the high-performance underlying networks. Our research here is motivated to glue the optical networks and grid applications by integrating lightpath, geographically distributed INS systems and grid resources (e.g., computers, storages, instruments, etc.), and finally offering an easy-to-use high performance networked grid computing environment-optical grid network (OGN) to user applications. In this paper, we introduce our research activities of a distributed optical grid network infrastructure (OGNI), and the creation of the future easy-to-use INS based on OGNI. The proposals have been validated through fieldtrial experiments over a developed WSON testbed.

Directional coupler (DC)-based optical switching networks can switch signals at the rate of several terabits per second. Benes networks are widely employed for their small depth and self-routing capability. Crosstalk between two optical signals passing through the same DC is an intrinsic drawback in DC-based optical networks. Vertical stacking of multiple copies of an optical Benes network has been intensively studied by researchers to build non-blocking optical networks. The resulting network is called vertically stacked optical Benes network (VSOBN). However, no rigorous analysis has been done to predict the behavior of VSOBN. In this paper, we study the deterministic conditions for strictly non-blocking VSOBN with and without worst case scenarios. We further analyze the blocking probabilities of VSOBN networks under a fixed load and develop their upper bound with respect to the number of planes in the networks. These performance measures can be used to predict the performance of VSOBN.

Optical networks are the backbone of today’s high-speed communication systems, but they can be attacked in many ways. Hackers might use advanced methods like wormhole attacks, Sybil attacks, or single-point failures to disrupt or take control of the network. Most current security systems rely on complex math to protect data. But with the development of quantum computers, those systems are no longer fully safe. Quantum computers could break these protections easily in the future. This problem can be solved by integrating two powerful technologies: Quantum Key Distribution (QKD) and blockchain This combination is called quantum-secured blockchain. This system removes the need for older, potentially breakable digital signatures, and instead uses methods that are resistant to quantum computer attacks. They also rely on new quantum materials and nanomaterials, which help in making better light sources, reducing signal loss and storing quantum information more reliably. AI and machine learning are now being used to speed up the discovery of these advanced materials such as superconductors, quantum dots and special optical fibers that are required to make the technology practical and scalable. This paper explains the different types of attacks that can occur in optical networks and the ways to protect optical networks using quantum-secured blockchain along. It gives the introduction to blockchain technology along with its security weaknesses, and then focuses on Quantum Key Distribution (QKD), which can make blockchain much stronger against attacks from powerful quantum computers. It also provides an overview of how quantum-secured blockchain works to secure optical communication networks.

We present a comprehensive overview of our original work on the theory, design, fabrication, and integration of micro/nano-scale optical circuits and networks (O-MNN). This is an extension of the macro-scale optical networks and electrical networks down to the level of micro/nano-scale. It also inte

Current and planned solutions used in the ICT infrastructure are largely based on Photonic and RF Communications Systems. Rapid advances in photonic and RF photonic technologies have significantly accelerated the introduction of these new technologies in access storage, backbone and grid networks, defining and building the rules to ensure transfer of multi Tera-bit volumes of data. The purpose of this volume is to provide a vehicle for directing research in this area from multiple lenses in the selected areas of investigation. Following an introduction by the editors, reviews of research will be clustered into two sections. The first part of this Special Issue focuses on the Photonic and RF Communications systems technologies and this Section comprises 7 articles. Recent solutions in wideband and multi-band RF circuits are presented in the articles 7 through 9 in the second part of the Special Issue. The first article, by Arash Bahrami , et al., present an experimental evaluation of a radio-over-fiber system. In the paper, the authors proposed an optical microwave radio-over-fiber system in which an integrated dual-parallel Mach-Zehnder modulator is biased at the maximum transmission biasing point. The authors consider the two following modulation schemes: binary phase shift keying (BSK) and quadrature phase shift keying (QPSK) over fiber spans of 10 and 25 km of standard single mode fiber. The obtained results show that the second order sideband of optical microwave has the potential to provide error-free transmission for BPSK and QPSK. John S. Vardakas , et al. in the next article, analyse the delay of converged Wavelength Division Multiplexing Ethernet Passive Optical Network and WiMax networks. In such access networks, the provision of Quality of Service (QoS) support is a challenging issue, mainly due to the different bandwidth allocation mechanisms of the two access technologies. In the paper, the authors analyse the delay performance by considering multiple service-classes with different priorities. The proposed analytical model allows the calculation of the average end-to-end packet delay of each service-class as the sum of the queuing delay in both domains. The accuracy of the analysis was verified by simulation. Ioannis Mamounakis , et al., propose a novel traffic prediction method to minimize packet delay in Ethernet Passive Optical Networks. The authors utilise traffic information to predict the accumulated burst size of each respective optical network unit in the following cycle. The paper demonstrates and proves that a significant delay enhancement can be accomplished by reporting the predicted burst size, rather than the current one, to the Optical Line Terminal (OLT). The simulation experiments carried out by the authors show that a significant decrease in the delay can be obtained without any changes to the dynamic bandwidth assignment scheme at the OLT. The paper by Mariusz Głąbowski , et al. proposes an analytical model of a multi-service switching network with overflow links with finite capacity in the first stage of the network. This model can be used to evaluate the QoS parameters which are closely interrelated with the method of operation of the large capacity optical nodes. The proposed method allows their traffic capacity to be increased through a significant decrease in the phenomenon of internal blocking in switching networks which is the basic element of the node. The proposed calculation method is validated by the authors via simulation. Aboagela Dogman , et al. present an integrated QoS management process for multimedia traffic in wire and wireless networks. In the proposed process, the statistics of traffic are determined and then used as an input to a fuzzy interface system (FIZ). FIZ allows the traffic to be accurately sampled and this traffic is in the next step pre-processed using a fuzzy c-means (FCM). FIZ identifies clusters representing poor, average and good QoS. This information is then used in a multilayer perceptron neural network to assess the overall QoS for multimedia traffic. The authors showed that the developed adaptive statistical sampling represents traffic more correctly than systematic, stratified and random non-adaptive sampling methods. The article by Adam Kaliszan , et al. provides a generalised convolution algorithm for modelling state-dependent systems. This model corresponds to the system that uses one or many physical resources, e.g. one or a set of lambda channels in DWDM optical networks. The proposed calculation method can be used for the analysis and dimensioning of optical networks and systems. This method is also useful for an optical system in which advanced traffic management mechanism have been applied, e.g. bandwidth reservation or threshold mechanism. The accuracy of the proposed model is validated by simulation experiments. From their onset RF Communications Systems have been critical to the development of ICT infrastructure. In mobile and satellite communication systems, wideband and multi-band RF circuits are important for achieving high-date wireless transmission and supporting a large number of standards (e.g. UMTS, WiFi, WiMAX, or LTE). A wideband or multi-band RF circuit can replace a number of single-band RF circuits, leading to a significant reduction of size, weight and cost of modern wireless systems. There have been a great number of recent developments in the above areas over the past years. The articles that outline these solutions are in the latter part of this Special Issue, i.e. comprise articles from Article 7 through Article 9. The article by Bingo Wing-Kuen Ling , et al. discusses the frequency spectrum of a pulse for ultra wideband impulse radio systems as the frequency response of a real valued causal rational infinite impulse response filter. The pulse design problem is formulated as a functional inequality constrained optimization problem that can be solved by the method proposed by the authors. This pulse can be generated via an excitation of a simple circuit. Numerical simulation results confirm that the energy compaction performance defined in the frequency domain of the proposed pulse outperforms that of existing pulses. It is worth emphasizing that the pulse can be generated via an excitation of a simple circuit. In their article, Xue Li and , et al. present the WiFi leakage problem that appears in the users' equipment that simultaneously use both LTE and WiFi technologies. The authors propose WiFi leakage detection algorithms for successful detection of the weak WiFi leakage in the presence of both LTE signal and Gaussian noise. The algorithms include energy ratio detection, entropy ratio detection and cyclostationary detection based on spectral correlation function. The effectiveness and efficiency of the proposed WiFi leakage detection techniques have been confirmed by simulations performed for different scenarios. The article by Piotr Remlein discusses the performance of Intelligent Transportation Systems (ITS) that consists of satellite mesh networks. In the paper the author analyses a new power-limited and energy-efficient systems employing coded continuous phase modulation signals and with multiuser Frequency Division Multiplexed transmission. The results obtained by the author show that good performance of the proposed solution can be achieved by reducing the inter-carrier frequency spacing and using simple iterative ICI cancellation algorithm at the receiver. Based on the results, it can be concluded that this system might constitute a desirable option in ITS satellite mesh, ad-hoc networks. The objective of this Special Issue is to bring together the state-of-the-art research contributions that address challenges in emerging devices and architecture for photonic systems and RF circuits for wideband and multi-band communications systems. Due to the complexity and scope of the subject area, the set of articles presented attempts to address only some selected relevant issues. The Guest Editors believe though that the contributions included in the Special Issue will inspire the research activities of leading authors and scholars worldwide. The Guest Editors also expect this Special Issue to provide insight into the questions that they address as the presented articles expose important contributions to each of the relevant subject areas. Piotr Zwierzykowski received MSc and PhD (Hons) degrees in telecommunications from Poznan University of Technology, Poland, in 1995 and 2002, respectively. Since 1995 he has been working at the Poznan University of Technology, where he is currently an Assistant Professor. Piotr Zwierzykowski is the author, or co-author, of over 200 journals and conference publications and three books in the area of computer and communication networks. His research covers modelling and dimensioning of optical networks, teletraffic engineering and routing. He is a Senior Member of IEEE and the Secretary in the IEICE Europe Section. Steven Gao received a PhD degree from Shanghai University, P.R. China. He is a Professor and Chair in RF and Microwave Engineering at University of Kent, UK. His research covers smart antennas, satellite antennas, phased arrays, RF and microwave circuits (power amplifiers), satellite communications, UWB radars, synthetic-aperture radars and mobile communications. From 2007 to 2012, he was a Senior Lecturer and Head of Space Antennas and Microwave System Group at Surrey Space Centre, University of Surrey, UK. He has two books including “Space Antenna Handbook” (Wiley, 2012) and “Circularly Polarized Antennas” (IEEE-Wiley, 2014), published over 200 papers and holds several patents in smart antennas and RF. He is an IEEE AP-S Distinguished Lecturer and a Chair of LAPC 2013. He is an Invited Speaker at IWAT'2014 (Sydney), SOMIRES'2013 (Japan), APCAP'2014 (China), etc. He is an Associate Editor of Radio Science and the Editor-in-Chief for Wiley Book Series on "Microwave and Wireless Technologies". He is a Fellow of the IET. Wai Pang Ng received his BEng (Hons) Communication and Electronic Engineering and IEE Prize from Northumbria University, UK and PhD in Electronic Engineering from University of Wales Swansea, UK in 1997 and 2001, respectively. He is a Reader of Optical Communications at Northumbria University. From 2001 to 2004, he was a Senior Networking Software Engineer at Intel Corporation, before starting his academic career at Northumbria University. He has published over 80 journals and conference publications in the area of optical switching, optical signal processing and radio-over-fiber. He is a Chartered Engineer of the Engineering Council UK and a Senior Member of the IEEE. Currently he serves as the Chair of the IEEE UK&RI Communication Chapter. He was also the Co-Chair of the Signal Processing for Communications Symposium in IEEE International Conference on Communications (ICC) 2009 (Dresden, Germany) and now serves as the Publicity Chair of ICC 2015 in London. Zuqing Zhu received a PhD degree from the Department of Electrical and Computer Engineering, University of California, Davis, in 2007. From July 2007 to January 2011, he worked in the Service Provider Technology Group of Cisco Systems, San Jose, as a senior R&D engineer. In January 2011, he joined the University of Science and Technology of China (USTC), where he is currently an Associate Professor. He has published more than 100 papers in peer-reviewed journals and conferences. He has been in the technical program committees (TPC) of INFOCOM, ICC, GLOBECOM, ICCCN and etc. He is also an editorial board member of Elsevier Journal of Optical Switching and Networking, Springer Telecommunication Systems Journal, Springer Photonic Network Communications Journal and Wiley European Transactions on Emerging Telecommunications Technologies amongst others. He has received the Best Paper Awards from the IEEE International Conference on Communications (ICC) 2013, the IEEE Global Communications Conference (GLOBECOM) 2013, and the IEEE International Conference on Networking and Communications (ICNC) 2014. He is a Senior Member of IEEE and OSA.

Optical links and photonic integrated circuits require integration of photonic and electronic devices at chip, module, or board level. The complexity of such systems is motivating a need for system level CAD tools which can simulate electronic and photonic devices and circuits simultaneously and at multiple levels of abstraction. Furthermore integrating photonic devices into conventional electronic computer and communication systems needs to be justified in terms of cost, performance, and portability of existing computer software and hardware. Thus system level analysis of optoelectronic interconnect system is clearly necessary to ensure that an overall functional and performance requirements are met. The proposed approach for system level modeling is to integrate photonic device simulations into the established electronic design automation environment, particularly VHDL-based one. VHDL description of photonic devices will provide benefits such as portability of individual design, system level performance analysis before building a real system, and synthesis capability for a rapid- prototyping. This paper demonstrates the use of basic VHDL entities of various passive optical waveguide components and a special VHDL package (`Optical_Package') defining physical photonic parameters to verify the feasibility of this approach. It includes modeling and simulation of global signal distribution network on MCMs using optical interconnect and wavelength division (de)multiplexing-based optical link.

As one of the key component of photonic crystal optical circuit devices, the directional coupler is investigated. We explain the reason the directional coupler consisting of an ordinary symmetric parallel waveguide cannot have a high extinction ratio and a small coupling length simultaneously. To realize both characteristics simultaneously, we propose a novel directional coupler structure. By numerical calculation, we show the possibility of a directional coupler with a high extinction ratio (-24 dB) and a small coupling length (18a).

Scheduling traffic for maximum switch lifetime in optical data center fabrics

Within the spectacular and notorious explosion of the information technology economy, the part dedicated to hardware developments remains partially hidden. Nevertheless, the photonic technology industry strongly participates to the present expansion especially in the telecommunication domain. The maturing of WDM technologies has provided the key towards success. The requirements for data transmission capabilities related to the development of the Internet and other network exchanges has been fulfilled. A major characteristic related to the development relies in the long-term research and component and device design required for the new generation of systems. Although original applications of optics was concentrated on point-to-point transmission, advanced optical network architectures foresee a wide use of the “optical parameter” as a main feature for the required exchanges between the various network levels (local, metropolitan, backbone...). It is clear that photonic components are the fundamental building block that will have to perform the functions now carried out in the electrical domain, in order to fully explore and implement the all-optical networks. The strategic choice of transmitted signal granularity in every network node determines the optical/electronic and the WDM/OTDM alternatives and relies on the new component performances. A first generation of devices for optical routing and processing has been proposed. It is mainly based on semiconductor optical amplifiers (SOAs) that provide the strong non­linear operation required through cross-phase and cross-gain modulation and four-wave-mixing. Non-linearities in optical fibers (self-phase modulation, Raman amplification...) have also lead to some interesting proposals. Major achievements have been realized in the field of wavelength converters and 3R regenerators. These devices and sub-systems are ready to be used in industrial deployments. Present and future research should focus on the enhancement of non-linear operation (through strong light spatial confinement for example...) or of device speed, while keeping in minds the requirements for integration. Photonic band-gap structures in semiconductors and microstructured optical fibers already appears as powerful candidates for a new generation of components. New semiconductor materials and extensive use of polymers enhance the application fields of photonics well beyond the telecom application domain. “The new generation optical communications networks are being built using devices that emerge from fundamental research from the last ten years... Pursuing this research into basic physics may lead to a completely new area of communication and computing, with perspectives that we are not likely to imagine today” (OPTIMIST)

Banyan networks are attractive for constructing directional coupler (DC)-based optical switching networks for their small depth and self-routing capability. Crosstalk between optical signals passing through the same DC is an intrinsic drawback in DC-based optical networks. Vertical stacking of multiple copies of an optical banyan network is a novel scheme for building nonblocking (crosstalk-free) optical switching networks. The resulting network, namely vertically stacked optical banyan (VSOB) network, preserves all the properties of the banyan network, but increases the hardware cost significantly. Though much work has been done for determining the minimum number of stacked copies (planes) required for a nonblocking VSOB network, little is known on analyzing the blocking probabilities of VSOB networks that do not meet the nonblocking condition (i.e., with fewer stacked copies than required by the nonblocking condition). In this paper, we analyze the blocking probabilities of VSOB networks and develop their upper and lower bounds with respect to the number of planes in the networks. These bounds depict accurately the overall blocking behaviors of VSOB networks and agree with the conditions of strictly nonblocking and rearrangeably nonblocking VSOB networks respectively. Extensive simulation on a network simulator with both random routing and packing strategy has shown that the blocking probabilities of both strategies fall nicely within our bounds, and the blocking probability of packing strategy actually matches the lower bound. The proposed bounds are significant because they reveal the inherent relationships between blocking probability and network hardware cost in terms of the number of planes, and provide network developers a quantitative guidance to trade blocking probability for hardware cost. In particular, our bounds provide network designers an effective tool to estimate the minimum and maximum blocking probabilities of VSOB networks in which different routing strategies may be applied. An interesting conclusion drawn from our work that has practical applications is that the hardware cost of a VSOB network can be reduced dramatically if a predictable and almost negligible nonzero blocking probability is allowed.

We present the results of our study on the micro/nano-scale design and fabrication of optical waveguide devices, photonic devices and sensors to be integrated in the form of optical printed circuit boards (O-PCBs) for various application. Application-specific O-PCBs are composed of varied forms of optical wires and devices tailored to perform specific functions. In this paper, we present two examples of application specific O-PCB. One is an all-optical wavelength splitting triplexer module that we designed for subscriber network application and the other is a grating array that we designed for temperature-sensor application. The triplexer module consists of an array of cascaded directional couplers to split the wavelengths for passive optical network and signal distribution application and the grating array is designed for wavelength splitting and temperature sensing applications. The advantages of these devices are that they can be readily fabricated out of polymer materials by way of thermal or ultraviolet (UV) embossing (or imprinting) technique. Theoretical calculations provide design rules for these devices. The results suggest that O-PCB can be a viable and useful platform for integration of various photonic devices for sensor application.

Miniaturization and performance enhancement of photonic devices remain key challenges in the advancement of optical information processing technologies and photonic neural networks. In this study, an inverted triangular resonator (ITR) based on a metal–insulator–metal (MIM) plasmonic architecture and phase-change material Ge2Sb2Te5 (GST) is introduced. By integrating a GST element with a volume of only 78,000 nm³ into the active region of the ITR, strong electromagnetic field confinement and optimized phase transition control are achieved. This design results in an unprecedentedly small footprint (0.031 μm²) and an outstanding optical contrast of 76% at the telecommunication wavelength of 1598 nm. The switching energy of this structure, estimated by numerical simulations, is about 7 pJ, placing it among the most energy-efficient photonic devices. The unique features of this structure—including the extremely small volume of active material, low energy consumption, high thermal stability, and excellent reliability—make it an ideal candidate for implementing tunable optical synapses in neuromorphic systems. Its fast nonlinear response and stable operation enable precise simulation of synaptic weighting and the implementation of learning algorithms in photonic architectures. These results demonstrate that the intelligent combination of plasmonic technology and phase-change materials in the ITR configuration can open new horizons in the design of ultra-compact, low-power photonic devices for next-generation neural networks and optical information processing.

We propose novel designs of optical vias to be used in high-density photonic integrated circuits (HDPICs), where photonic crystal (PhC) optical networks are used for spatial optical signal distribution and routing through multiple planes and in different directions. These optically conducting networks with their ability to guide light are an optical analogy to electrical circuits, in particular printed circuits boards (PCBs), which transport electrons through electrical networks. Different techniques for in- and out-of-plane broadband as well as narrow-band coupling between various PhC devices and layers are discussed. Numerical analyses were performed using the finite-difference time-domain (FDTD) method with appropriate boundary conditions.