Recent developments in communication technology contributed to the growth of network traffic exponentially. Cost per bit has to necessarily suffer an inverse trend, posing several challenges to network operators. Optical transport networks are no exception to this. On one hand, they have to keep up with the expectations of data speed, volume, and growth at the agreed quality-of-service (QoS), while on the other hand, a steep downward trend of the cost per bit is a matter of concern. Thus, the proper selection of network architecture, technology, resiliency schemes, and traffic handling contributes to the total cost of ownership (TCO). In this context, this chapter looks into the network architectures, including the optical transport network (OTN) switch (both traditional and universal), resiliency schemes (protection and restoration), flexible-rate line interfaces, and an overall strategy of handover in between metro and core networks. A design framework is also described and used to support the case studies reported in this chapter.

The book Optical Fiber and Wireless Communications provides a platform for practicing researchers, academics, PhD students, and other scientists to review, plan, design, analyze, evaluate, intend, process, and implement diversiform issues of optical fiber and wireless systems and networks, optical technology components, optical signal processing, and security. The 17 chapters of the book demonstrate capabilities and potentialities of optical communication to solve scientific and engineering problems with varied degrees of complexity.

The increasingly important role of Internet-based, “cloud” service delivery is motivating the evolution of the Internet to a flatter hierarchy of more densely interconnecting networks that shall cost-effectively scale to Zettabytes of bandwidth with improved operational efficiency, under increased traffic variability, and forecast unpredictability. This chapter reviews the implications of this evolution in its underlying metro regional and core transport network architectures, and evaluates the most important innovations in photonics, optical transport, routing, and traffic engineering technologies enabling it. Most notably, 1) a new generation of coherent DWDM systems with more than 2 b/s/Hz spectral efficiency is scaling the existing fiber infrastructure, albeit at a significantly higher proportion, typically more than 50%, of the total transport network cost, while 2) the convergence of IP/MPLS with flexible DWDM promises the most cost-efficient transport evolution, in open architectures that combine advancements in photonics, routing, multi-layer control-plane and management coordination, with interoperability, to improve operation, automate provisioning and restoration, and may optimize network utilization.

"The burgeoning capacity demand for both optical transport links over metro / long-haul distances (> 100km) and short reach optical interconnects (100m-20km) for inter- and intra-datacenter networking is driving the notion of a digital signal processing (DSP) based optical transceiver. In optical transport, flexible optical transceivers employ coherent detection and DSP to enable mitigating various fiber transmission impairments such as chromatic dispersion (CD), polarization mode dispersion (PMD), Kerr nonlinearity, laser phase noise and frequency offset. In addition, these flexible transceivers need to be agile enough to adapt to the increasingly dynamic network traffic needs (e.g. varying capacity and reach requirements, dynamic wavelength assignments). On the short reach side, cheap and power efficient optics is a necessity for datacenter applications and hence intensity modulation / direct-detection (IM/DD) prevails over coherent detection. For such IM/DD transceivers, photonic integration is envisioned to play a significant role in reducing the cost along with DSP that potentially allows increasing the delivered bit rates with cheap electronics and reduced number of optical components (and consequently footprint).In the first part of the thesis, we propose and verify, both analytically and experimentally, a myriad of DSP algorithms suitable for implementation in flexible optical coherent transceivers for transport networks. The proposed DSP algorithms tackle impairments such as laser phase noise, frequency offset, polarization rotation, fiber Kerr nonlinearity and sampling frequency offset. For each of the proposed algorithms, we provide a performance comparison with the standard counterparts in the literature highlighting the advantages of our approaches together with the underlying tradeoffs. Next, we develop and experimentally verify a rigorously derived analytical model for performance evaluation of a flexible coherent optical front-end that can operate colorlessly in a wavelength division multiplexing (WDM) scenario, i.e. without the need for a WDM demultiplexing filter prior to the receiver. The accuracy of the developed model was proved by finding a close match between model predictions and experimental results. We finally show that the model can be used as a useful system design tool to predict the system performance at various operating scenarios.In the last part of the thesis, we propose a DSP algorithm to enable polarization division multiplexing (PDM) in IM/DD transceivers for short reach optical interconnects. This doubles the achievable bit rate with the same speed of the electronic components and with the same number of light sources by exploiting the two orthogonal polarization states per source. The proposed DSP algorithm is based on a multiple-input and multiple-output (MIMO) finite impulse response (FIR) filter that operates on the Stokes parameters of the received field, which can be obtained via a direct-detection receiver front-end, to invert the random rotations that occurred along the fiber. The proposed DSP was verified experimentally using an IM/DD transceiver that employs a single 1310 nm laser whose both polarizations were modulated by a packaged silicon photonic (SiP) intensity modulator. A record bit rate of 224 Gb/s was transmitted over 10 km with a BER below the forward-error-correcting (FEC) threshold." --

This handbook is an authoritative, comprehensive reference on optical networks, the backbone of today’s communication and information society. The book reviews the many underlying technologies that enable the global optical communications infrastructure, but also explains current research trends targeted towards continued capacity scaling and enhanced networking flexibility in support of an unabated traffic growth fueled by ever-emerging new applications. The book is divided into four parts: Optical Subsystems for Transmission and Switching, Core Networks, Datacenter and Super-Computer Networking, and Optical Access and Wireless Networks. Each chapter is written by world-renown experts that represent academia, industry, and international government and regulatory agencies. Every chapter provides a complete picture of its field, from entry-level information to a snapshot of the respective state-of-the-art technologies to emerging research trends, providing something useful for the novice who wants to get familiar with the field to the expert who wants to get a concise view of future trends.

This book takes a pragmatic approach to deploying state-of-the-art optical networking equipment in metro-core and backbone networks. The book is oriented towards practical implementation of optical network design. Algorithms and methodologies related to routing, regeneration, wavelength assignment, sub rate-traffic grooming and protection are presented, with an emphasis on optical-bypass-enabled (or all-optical) networks. The author has emphasized the economics of optical networking, with a full chapter of economic studies that offer guidelines as to when and how optical-bypass technology should be deployed. This new edition contains: new chapter on dynamic optical networking and a new chapter on flexible/elastic optical networks. Expanded coverage of new physical-layer technology (e.g., coherent detection) and its impact on network design and enhanced coverage of ROADM architectures and properties, including colorless, directionless, contentionless and gridless. Covers ‘hot’ topics, such as Software Defined Networking and energy efficiency, algorithmic advancements and techniques, especially in the area of impairment-aware routing and wavelength assignment. Provides more illustrative examples of concepts are provided, using three reference networks (the topology files for the networks are provided on a web site, for further studies by the reader). Also exercises have been added at the end of the chapters to enhance the book’s utility as a course textbook.

Using simple language, this text explains the properties of light, its interaction with matter, and how it is used to develop optical components such as filters and multiplexers that have applications in optical communications. The text also introduces the evolving dense wavelength division multiplexing (DWDM) technology and communications systems.