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Lightwave Technology, Journal of

Issue 11 • Date Nov 1989

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Displaying Results 1 - 25 of 31
  • Fiber-optic point-to-multipoint interface configuration for broad-band ISDN

    Page(s): 1849 - 1858
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    The physical layer characteristics and hardware implementation of broadband ISDN user-network interfaces are discussed. Optical fiber cable is employed as the transmission medium due to its broad bandwidth and low loss characteristics. For terminal connections in customer premises, a point-to-multipoint wiring configuration is adopted. The techniques needed to develop the fiber-optic point-to-multipoint transmission capability to realize an effective fiber-optic point-to-multipoint interface are discussed. A frame phase alignment procedure, a burst-mode automatic optical output power circuit for a laser diode, and bit timing extraction and DC-wandering cancellation for optical bursty signals are introduced. Experimental results demonstrate the feasibility of 1-km optical interface transmission at speeds over 140 Mb/s in a point-to-multipoint wiring configuration connecting up to eight terminals View full abstract»

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  • Subscriber single-mode optical fiber ribbon cable technologies suitable for midspan access

    Page(s): 1675 - 1681
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    The loop network configuration and high-fiber-count, single-mode optical fiber ribbon cable and jointing technologies which enable a quick response to service demand and offer high reliability in the subscriber network are described. Fiber parameters were chosen for 1.3/1.55-μm wavelength division multiplexing (WDM) transmission, and a 1000-fiber cable composed of 8-fiber ribbons was developed. A mass-fusion splicing technique and a multifiber connector were developed for the fiber ribbon. These techniques were evaluated by constructing an experimental line. It was found that they are highly suitable for midspan access, which is indispensable for the high-fiber-count loop network View full abstract»

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  • H-Bus: an experimental ATM-based optical premises network

    Page(s): 1859 - 1867
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    An optical customer premises network (CPN), called H-Bus, designed to interface future broadband ISDN signals and distribute available bandwidth to terminal equipment connected to the CPN, is discussed. Key features of this network are the use of optical fiber as a transmission medium and a hybrid architecture, namely, a broadcast bus for the downstream (network interface to subscriber terminal) and a looped bus for the upstream (subscriber terminal to network interface) traffic. The physical layer of the network makes use of the synchronous optical network (SONET) transmission format. The user information is carried using the asynchronous transfer mode (ATM) technique. The reliability of H-Bus is improved through the use of a network component called an optical protection socket (OPS). This is an automatic optical bypass switch that protects the CPN in the case of individual node failures. To resolve any access contention on the upstream bus, a multipriority media access control protocol has been defined. Its performance is compared with that of protocols used in other high-speed local area networks View full abstract»

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  • Smart optical receiver with automatic decision threshold setting and retiming phase alignment

    Page(s): 1634 - 1640
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    The requirements for a smart optical receiver are discussed, and a design architecture suitable for introducing ICs based on automatic decision threshold setting and retiming phase alignment using digital/analog signal processing feedback is proposed. With the proposed architecture, the decision threshold level and the retiming clock phase of received data in the decision circuit are automatically adjusted to the optimum position. This obviates the need for decision threshold level and retiming clock phase adjustments in production testing, and it reduces the power penalty (receiver sensitivity degradation) on the received optical waveform variation. The power penalty caused by temperature and supply-voltage variations and aging in installation is also reduced. The performance of the proposed architecture is estimated; the power penalty as compared with the manual optimum adjustment is less than 0.4 dB, and the robustness to avalanche photodiode multiplication factor variations and crosstalk are improved View full abstract»

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  • An optimal investment strategy model for fiber to the home

    Page(s): 1868 - 1875
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    Planning for the deployment of fiber to the home is made particularly difficult by rapidly changing network component costs and a multitude of system architecture alternatives. A modeling approach using dynamic programming to select an optimal investment strategy for rehabilitating existing copper plant with fiber to the home is described. The optimal time to invest is determined by a simple tradeoff: early deployment allows the carrier to receive additional revenues from video services more quickly; later deployment can be accomplished with less costly technology. Given the assumptions of the model about component cost trends and demand forecasts, and in the absence of competition, the model predicts that discounted profits to a local exchange carrier (LEC) are maximized by deferring investment in fiber to the home until well into the 21st century. The results are particularly sensitive to a few system parameters: the assumed rate of subscriber growth in broadband services, the cost of optical components, and the cost of network maintenance. Some policy implications of the study are examined View full abstract»

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  • Optical fiber cables for subscriber loops

    Page(s): 1667 - 1674
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    The use of single-mode optical fiber cables in the local network is discussed. For various network structures, cable constructions with loose buffered fibers, ribbon, and V-groove elements are discussed. For star networks, cables with up to 2000 fibers are described. Cables for bus/star networks are also discussed. Splicing techniques and enclosures are considered. It is concluded that only mass splicing technologies with ribbons will lead to the required results View full abstract»

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  • An engineering and policy analysis of fiber introduction into the residential subscriber loop

    Page(s): 1876 - 1884
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    An engineering model which provides a framework for evaluating alternative network architectures for providing fiber to the home is presented. The analysis employs this model to construct estimates of the average cost per subscriber of several network alternatives which have been proposed in the literature. The results identify two possible network architectures, the active double star and the passive double star, as particularly attractive alternatives. Sensitivity analyses provide detail on the critical contributors to overall costs. Several policy issues raised by the analysis, including the proper allocation of risk from fiber-to-the-home investments, are considered View full abstract»

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  • Bragg gratings on InGaAsP/InP waveguides as polarization independent optical filters

    Page(s): 1641 - 1645
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    The fabrication and operation of Bragg gratings for future wavelength-division multiplexing (WDM) devices in integrated optical circuits are discussed. Crosstalk attenuation of more than 20 dB with respect to the optical power and spectral bandwidths of up to 2.2 nm were achieved. Polarization-independent operation of the gratings, an important qualification for their operation in fiber optical transmission systems, was demonstrated with a filter bandwidth of 0.2 nm at -10 dB and channel spacings as small as 1 nm View full abstract»

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  • Technology and system issues for the WDM-based fiber loop architecture

    Page(s): 1759 - 1768
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    A fiber-optic subscriber loop architecture employing multichannel wavelength-division multiplexing (WDM) techniques is discussed. The architecture, which is called the passive photonic loop (PPL), eliminates the need for outside-plant multiplexing and routing electronics while maintaining complete compatibility with broadband ISDN. An experimental demonstration of the PPL employing 32-channel WDM and a combination of distributed-feedback (DFB) laser and light emitting diode (LED) transmitters is described. A family of alternative PPL implementations is identified. Tradeoffs between these alternatives are explored, and related hardware issues such as wavelength alignment and WDM-component temperature sensitivity are discussed. An economic analysis comparing the PPL with the use of dedicated fiber between the central office and customer premises is presented. The analysis predicts that the PPL can achieve a cost advantage for at least 80 to 90% of the subscribers served in today's network, given DFB-laser and dense-WDM-component cost reductions of approximately one order of magnitude from today's unit-quantity prices View full abstract»

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  • Fiber-optic switch arrays for optical subscriber transmission systems

    Page(s): 1661 - 1666
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    Optical array devices play an important role in subscriber transmission systems because they can efficiently accommodate the large number of optical channels required. The use of two single-mode fiber-optic switch arrays in subscriber transmission systems is discussed. The first is a 16-element micromechanical switch array which is electrostatically driven and is used to separate abnormal subscriber units that transmit disturbing light signals. The second is a 16-element switch array which interconnects a pair of probe fibers and any one of 16-channel subscriber-line fibers to execute fault testing View full abstract»

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  • Filter-embedded design and its applications to passive components

    Page(s): 1646 - 1653
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    A design in which a filter is embedded in a fiber fixed on a substrate is proposed. It was successfully applied to the fabrication of low loss fiber optic components for a single-mode fiber transmission system. These components have a wide operational temperature range. The design is easily adapted to a multifilter or multifiber component. Filter embedding is achieved in two ways. One is to insert a thin filter chip in a slit which is machined into a fiber fixed on a substrate by a dicing saw (filter inserted type). The other is to evaporate a filter film directly on a fiber end face and butt this fiber to another fiber on a guide groove on a substrate (filter evaporated type) View full abstract»

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  • Subcarrier multiplexed lightwave system design considerations for subscriber loop applications

    Page(s): 1806 - 1818
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    Design considerations for subscriber multiplexed (SCM) systems distributing multichannel analog/digital signals are reviewed. In particular, video distribution schemes based on lightwave transmission technologies are discussed. The two most important system design considerations in an SCM system are the control of intensity noise and nonlinear distortions. Intensity noise characteristics and degradation caused by optical reflections are discussed. Laser and detector linearity requirements are reviewed. System signal-to-noise ratio analysis is performed. Design considerations for receivers for SCM systems are reviewed, and various system applications are examined View full abstract»

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  • Optical architecture and interface lightguide unit for fiber-to-the-home feature of the AT&T SLC Series 5 carrier system

    Page(s): 1727 - 1732
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    The subscriber loop has evolved from analog transmission on passive copper through digital carrier on copper to initial applications of fiber to customer premises. In planning its initial deployment of fiber to customer premises, AT&T analyzed a variety of optical devices and transmission techniques. It was decided to employ 1300-nm laser-based baseband duplex transmission employing fused fiber splitter devices. An optical interface lightguide unit was designed to house the optical components and protect them during assembly to a transceiver circuit board. This unit has proved compatible with a mass production factory environment. The optical transceivers have been deployed to sites throughout the US and have been performing reliably since the fall of 1988. The author discusses the choice of media, source, and wavelength; the lightguide unit; and the system characteristics View full abstract»

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  • The analog local loop: a growing revolution in optical transmission

    Page(s): 1819 - 1824
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    To provide an economic justification for the widespread deployment of optical fiber in the local loop, it may be necessary in some situations to install networks which will carry only telephony but can be upgraded to provide broadband services. Methods by which this may be achieved using analog carrier techniques are discussed. Passive optical networks (PONs) are considered, and the application of plain old telephone service (POTS) and broadband services over PONs is considered. Frequency planning and future trends are summarized View full abstract»

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  • SC-type single-mode optical fiber connectors

    Page(s): 1689 - 1696
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    SC-type single-mode optical fiber connectors specifically developed for subscriber loop networks are discussed. The properties and design of precision zirconia ceramic ferrules which have been found to be ideal for high-performance, low-cost single-mode optical fiber connectors are described. A design approach featuring a plastic-molded rectangular connector housing using a push-pull coupling mechanism which has also been found to be suitable for durable, compact, and low-cost connectors is presented. SC connectors used with 10/125 single-mode fibers exhibit insertion loss of 0.06 dB and return loss of 38.6 dB, with no degradation during and after mechanical and environmental tests. To realize higher packaging density, duplex-ferrule connectors, quadruple-ferrule connectors and optical attenuators have also been developed on the basis of the SC connector design View full abstract»

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  • Passive components in the subscriber loop

    Page(s): 1623 - 1633
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    The status of passive optical components for optical fiber subscriber loop systems is reviewed in the context of the most often discussed architectures. These architectures and the passive component types and functions are described. It is shown how the components are meeting the key functional requirements of interconnection, furcation, and filtration. A logic flow to the evolution of the architecture which is based on the expected development of the passive components is indicated View full abstract»

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  • Flexible synchronous broad-band subscriber loop system: optical shuttle bus

    Page(s): 1788 - 1797
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    A flexible, synchronous, broadband subscriber loop system called the optical shuttle bus is discussed. The emphasis is on the proposed design architecture and performance of a 1.8-Gb/s prototype system. The optical shuttle bus is constructed of multigigabit/second intelligent optical shuttle nodes (OSNs). The software-defined OSNs allow the bus to be configured as a synchronous transmission network with any topology and provides flexible channel allocation by means of a drop/insert/cross-connect function. The OSN can be configured as a highly reliable network by virtue of its self-healing functions such as line switch, bypass, and loop back. The proposed bus architecture has been successfully applied in a 1.8-Gb/s prototype in which three OSNs are connected by one 10-km and two 5-dm single-mode fibers in a ring configuration. Very compact and inexpensive equipment is realized by using high-speed ICs. Experimental results show the proposed architecture to be a powerful one for the realization of synchronous broadband subscriber loop systems View full abstract»

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  • RACE Project R1030, ACCESS-a system study of the broad-band subscriber loop

    Page(s): 1715 - 1726
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    The ACCESS project, which is a project within the RACE (Research in Advanced Communication in Europe) program, is described. The scope of the project is to study the entire customer access connection, including the transmission, the multiplexing, and the passive optical network. The goal of the project is to perform an overall cost optimization, leading to one or more preferred implementations. Because the project is oriented toward the early phases of the integrated broadband network, the majority of the effort is spent on optimization and supplementation of present near-commercial technologies. The project involves 13 partners who share the work organized in three major areas, namely, the 622 Mb/s transmitter/receiver unit for bidirectional transmission on one single-mode (SM) fiber at 1330 and 1550 nm; the passive optical components, including mass splicing techniques, low-cost connectors, wavelength division multiplexing (WDM) devices, optical distribution frames, and optical cables; and system aspects of the frame structure and the interfaces to the customer premises network and to the exchange, with the associated functional units being the multiplexers and the broadband channel selector View full abstract»

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  • Passive optical subscriber loops with multiaccess

    Page(s): 1769 - 1777
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    Deployment of optical fiber in the subscriber loop may eventually lead to a full-scale deployment of the broadband network. A network architecture that can be introduced inexpensively to meet the near-term demand and upgraded smoothly to support future needs is desired. The feasibility of applying multiaccess architectures to subscriber loops is studied, and five architectures for passive optical subscriber loops that meet this need are presented. All of these architectures use a double-star topology and dense wavelength division multiplexing in the downstream direction; however, various topologies and multiaccess techniques are used in the upstream direction. Limitations on node size, frame synchronization, cost, privacy and security, and standards are discussed View full abstract»

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  • A hybrid lightwave transmission system for subcarrier multiplexed video and digital B-ISDN services in the local loop

    Page(s): 1839 - 1848
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    Lightwave-subcarrier-multiplexed (SCM) transmission systems can provide high-capacity and low-cost delivery of both current and future advanced TV signals. Compatibility of SCM technology with existing baseband digital transmission equipment would eliminate the need for a separate analog distribution network and thereby permit a more graceful evolution to a broadband integrated digital services network (B-ISDN). One version of a hybrid system whereby SCM video and baseband digital signals are simultaneously transmitted by a single laser diode, and the technical issues related to such an implementation are considered. An experiment is discussed in which the three color components of a high-definition TV (HDTV) signal and a baseband 622.08-Mb/s SONET STS-12 rate data signal are transmitted simultaneously by a DFB laser diode via frequency-modulated (FM) subcarriers, over 2 km of a single-mode fiber View full abstract»

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  • Lightwave subscriber loop systems toward broad-band ISDN

    Page(s): 1705 - 1714
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    The state-of-the-art of lightwave subscriber loop systems is reviewed. An approach is described for deriving an architecture for subscriber loop systems that can accommodate technological trends in broadband ISDN such as asynchronous transfer mode (ATM) and synchronous digital networks. Key component technology is discussed, namely, optical fibers and cables, splicing and connectors, and switching View full abstract»

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  • Single-mode fiber WDM unit for duplex subscriber link using a substrate with embossed alignment grooves

    Page(s): 1654 - 1660
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    A wavelength division multiplexing (WDM) unit for single-mode fiber (SMF) duplex transmission, with light source, photodiode (PD), and WDM coupler arranged on a common substrate, is described. Using a tolerant optical design, the optical elements, e.g. lenses and fibers, are positioned in embossed high-precision V grooves without active adjustments. Only the light source, a laser diode (LD) or an edge-emitting LED (ELED), must be aligned for optimum coupling and fixed by laser welding. Typical values of LD-to-fiber and fiber-to-PD coupling loss and crosstalk are 5 dB, 1.2 dB, and -44 dB, respectively. Hence, in spite of the potentially low-cost design, the optical performance of the device is virtually competitive with separated transmitter and receiver units View full abstract»

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  • Optical networks for local loop applications

    Page(s): 1741 - 1751
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    Some of the options for optical technology within the local loop environment are examined. In particular, passive shared access networks have been considered in some detail. These networks show great promise for delivering existing telephone services to small to medium business customers (4-30 lines) economically by the early 1990s. Extending fiber to the home will also be possible by virtue of a similar passive network infrastructure for customers requiring new broadband services beyond the single telephone line. For one-line plain old telephone service (POTS) customers, an intermediate approach of terminating the fiber network at the final network distribution point, with copper retained for the final leg, may be used prior to the provision of broadband services. A key feature of the passive optical network architecture is the use of wavelength-division multiplexing (WDM) as an upgrade strategy, allowing graceful upgrading from telephone services to multichannel high-definition television (HDTV) on gigabit/second bearers and full two-way switched broadband services employing wavelength routing across the network View full abstract»

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  • Two fibers or one? (a comparison of two-fiber and one-fiber star architectures for fiber-to-the-home applications)

    Page(s): 1733 - 1740
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    Issues for consideration when deciding between the two-fiber (2-F) and one-fiber (1-F) architectures for fiber deployment in the distribution portion of the loop are presented. A link-loss assessment of both architectures is presented. 1-F star transmission concerns, namely, directivity and wavelength isolation, are discussed. System upgrade of both architectures is considered. Testing and maintenance are addressed. A cost analysis is presented. The 2-F star is conceptually a simple architecture offering maximum upgrade potential and few transmission and testing concerns. However, its distribution link and life cycle costs exceed that of the 1-F star. The 1-F star offer potential cost savings in fiber cable, splicing, and long-term maintenance. The 1-F star has transmission concerns, however, that could impose limitations on the type of transceivers and other loop components being deployed, and this could result in higher system costs View full abstract»

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  • Photonic highway: broad-band ring subscriber loops using optical signal processing

    Page(s): 1798 - 1805
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    The introduction of optical signal processing technology into transmission systems and basic experiments with optical drop/insert using bistable laser diodes are discussed. With broadband integrated services digital network (B-ISDN) architecture and technology now under study, optical signal processing (OSP) is being considered to increase network capacity and flexibility. B-ISDN will require over 40 Gb/s in the feeder loop that connects the central office and remote terminals having drop/insert function. Remote terminals will process large amounts of high-speed data. An OSP-based broadband subscriber loop photonic highway that uses a ring architecture linking photonic access nodes (PANs) that directly process optical signals is proposed. Each PAN has an optical drop/insert function and can synchronize optical frame signals using a proposed optical sampling memory. Optical drop/insert experiments confirmed the feasibility of the proposed method View full abstract»

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Aims & Scope

The Journal of Lightwave Technology contains articles on current research, applications and methods used in lightwave technology and fiber optics.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Peter J. Winzer
Alcatel-Lucent Bell Labs