Optical Transport Systems Research Articles

Managing the management communications network in optical transport systems

Management of today's optical transport networks typically includes some or all of fault, configuration, accounting, performance, and security (FCAPS) management. Carrying this management information across the network requires the presence of a management communications network (MCN), also referred to as the data communications network (DCN). The MCN itself needs FCAPS management. The availability of management for the MCN is very sparse in today's management systems, and this paper is a first step towards addressing the problem. We describe algorithms for planning, designing, and analyzing the MCN. Central to these algorithms is a graph representation of the entire network. Our treatment views the management of the MCN as an extension of the management of the transport network. We envision this work as the basis for a suite of applications that can improve the management of the communications infrastructure in optical transport networks.

Long-distance Transport of Directly Modulated Fiber Optical CATV System over 100 km Large Effective Area Fiber

This study presents a directly modulated 1550 nm NTSC AM-VSB 77-channel fiber optical CATV long-distance transport system using push-pull preamplifier and large effective area fiber (LEAF). Good performances of carrier-to-noise ratio (CNR) 50 dB, composite second order (CSO) 62 dB and composite triple beat (CTB) 61 dB were obtained over a 100 km LEAF transport. Compared with a conventional externally modulated system, our proposed system does not require expensive externally modulated transmitter, sophisticated stimulated Brillouin scattering (SBS)-suppression and differential detection techniques, as well as CTB-predistortion circuit. This proposed directly modulated transport system is simpler and more cost-effective than the conventional externally modulated transport system.

First demonstration of native Ethernet optical transport system prototype at 10 Gb/s based on multiplexing of gigabit Ethernet signals

The first system to transport native Ethernet data at a serial rate of 10 Gb/s is reported. Up to 8 asynchronous gigabit Ethernet signals are multiplexed to 10 Gb/s and directly modulate a Fabry-Perot laser at 1310 nm for 2-8 km transport over standard single-mode fiber bidirectional full-duplex communication between individual gigabit Ethernet hosts is demonstrated. System operation is entirely based on the physical layer signaling standards for gigabit Ethernet. Solutions to unique Ethernet synchronization and control problems are presented, and novel differences between multiplexed 8b/10b data and pseudorandom bit sequences are shown. Optical link performance and packet loss rates are presented.

On the value of optical-layer reconfigurability in IP-over-WDM lightwave networks

As packet traffic threatens to rapidly dominate core lightwave networks, while IP-router architectures take aim at multi-Tb/s capacities, a fundamental architectural question is beginning to take shape. Will the simple expedient of directly connecting IP routers to wavelength-division-multiplexing (WDM) optical-transport systems offer decisive economies in emerging core-transport networks, or is there yet a role for an added layer of reconfigurable wavelength-level circuits interposed among router ports? By examining regular network topologies with uniform and random traffic, we show that by adding a reconfiguring optical layer one reaps large economies, so long as router ports remain marginally more costly than optical-layer crossconnect ports. These economies are essentially invariant with nodal degree over the range of interest in lightwave networks. They grow rapidly with network node count. The results offer a compelling case for incorporating optical-layer crossconnects in large datacentric core-transport networks, and suggest that the resulting economies will rise rapidly as the network itself grows.

Optical beam transport system at FEL-SUT

Kawasaki Heavy Industries Ltd. has installed an FEL beam transport system at the IR FEL Research Center of the Science University of Tokyo (FEL-SUT). This system transports the FEL output beam from the FEL machine room to the optical diagnostic room through a vacuum tube. The in-vacuum multi-mirror synchronized system operated from the FEL control room enables the operator to control the multiple mirrors simultaneously on or off axis of the FEL beam and to distribute the FEL output to one of the laboratories. The essential component of the transport system is the passive control optics that is composed of an elliptical and parabolic mirror couple. Once the control optics is aligned, a parallel FEL beam with a good pointing stability is obtained without any active operation to tune the optical system for different wavelengths.

Full-duplex broadband millimetre-wave optical transportsystem for fibre-wireless access

A full-duplex, optical feeder network for wireless access operating at 39 GHz is presented. The system transports 155 Mbit/s of data and three video channels downstream, and 51.8 Mbit/s upstream over 40 km of standard singlemode fibre. The 39 GHz carrier signal was generated using a novel tripling technique which enables low frequency electronics and optical components to be implemented in the central office. The architecture also incorporates simple, low cost remote base-stations with no millimetre-wave upconverting mixers required. To further minimise cost, an LED was used as the optical source for upstream transmission.

Optical cavity and transport system for FELI

Optical cavity and transport system for FELI

Phase-space description of synchrotron radiation optics (invited) (abstract)

A study of the optics of synchrotron radiation in a fundamental level is important in view of the recent progress in synchrotron radiation research utilizing high brightness radiation from insertion devices, especially undulators, in low emittance storage rings. Important problems in synchrotron radiation optics are; How the strength of the various synchrotron radiation sources can be characterized in a manner independent from the optical transport system. How do the coherence properties of the synchrotron radiation differ from other sources such as lasers? How does radiation propagate through optical elements? What is the role of electron beam emittance in these respects, etc.? In this paper we review a theoretical formalism which can be a basis of a systematic study of synchrotron radiation optics. The approach, which will be called ‘‘The Phase Space Method of Synchrotron Radiation Optics,’’ starts from the Wigner distribution of electric fields and is a generalization of the phase space method of geometric optics to physical optics.

Optical beam transport system design for the Vanderbilt University free-electron laser

Abstract The initial design constraints and system requirements are given, and the design satisfying these requirements is presented. The optical requirement for beam quality dictates a design that is intrinsically without astigmatism. The optical design and its integration with the technical system is discussed. Broad spectral operation from 1–8 μm requires that the optical beam transport system (OBTS) be evacuated, due to atmospheric absorption that would otherwise occur.

Demonstration of harmonic lasing in a free-electron laser.

It has long been known that gain exists at the odd harmonics of a free-electron laser. Using a dispersive intracavity element to alter the cavity lengths for the fundamental and harmonic lasing, we have demonstrated harmonic lasing between 1.4 and 1.8 \ensuremath{\mu}m using the Stanford Mark III infrared free-electron laser. Gain at the third harmonic was seen to agree with theory to within experimental limits. The wavelength of the third harmonic was not quite equal to one third of the fundamental due to saturation and bandwidth effects. Power output was somewhat smaller than expected. This may have been due to losses in the optical transport system.

An approach to developing an infant mortality requirement for fiber optic transport systems

The approach used in developing an infant mortality requirement for fiber optic transport systems used in Bellcore client networks is described. Two generic parameters are considered: failure rate ratio, which is the ratio of the instantaneous failure rate to the steady-state failure rate, and infant mortality factor, which is the ratio of the expected number of failures in the first year of service to the expected number of failures in a steady-state year. Each of these parameters is discussed, and two methods of deriving a value for the infant mortality requirement are discussed. The first, a time-effective method, analyzes the infant mortality models to determine when there has been sufficient decay in the rate of change of the number of failures. The second, a cost-effective method, analyzes the models to determine a point at which overall costs are minimized.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

An availability requirement for fiber optic transport systems in distribution feeder applications

Abstract This paper contains a discussion of Bellcore's proposed channel availability requirement for fiber optic transport systems used in distribution feeder applications. A representative model of the distribution network is first constructed which includes a high capacity fiber optic system running to a distribution hub. An overall availability requirement, consistent with present availability requirements, is applied to this model. The allocation to the fiber system is determined by truncation of the current interoffice channel availability requirement which is prorated with distance. Further allocation of downtime to the electronic hardware reliability failures yields an objective that can be directly compared with the results of electronic hardware reliability models. This requirement is now included in Bellcore's proposed “Generic Reliability Assurance Requirements for Fiber Optic Transport Systems.”

Fiber Optic Transport Systems for Present and Future Local Networks

This paper describes fiber optic transport systems for present and future local networks. The present most important fiber optic system in a local network emerges as a broad-band video distribution system, because large-scale system introduction might be attained only for distributed video services. The system architecture and system parameters are presented. As for future integrated services, a highspeed digital transmission system and local network architecture are very important. The network architecture should be constructed to meet the demands for increased flexibility, capacity, reliability, and economy. Considering expected future demands and technologies, a new fiber optic local network architecture is proposed. The architecture's main features are the use of transmission processing nodes and a multilane-ring structure in subscriber transfer networks in combination with star-shaped subscriber access lines.