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Optical Communications and Networking, IEEE/OSA Journal of

Issue 9 • Date Sept. 2012

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Displaying Results 1 - 21 of 21
  • [Front cover]

    Page(s): c1
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    Freely Available from IEEE
  • [Front inside cover]

    Page(s): c2
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    Freely Available from IEEE
  • Table of contents

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    Freely Available from IEEE
  • Enabling optical devices for scalable networks: Introduction to the feature issue

    Page(s): EOD1
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    Scalability in terms of both capacity and energy are gaining increasing focus as potential bottlenecks for future optical communication networks. Traffic growth is outpacing the rate of network efficiency improvements as well as the rate of optical system capacity improvement. Laboratory results are rapidly approaching the fiber transmission spectral efficiency limits. The energy efficiency benefits derived from Moore's law scaling are slowing. Research is under way today to address these challenges, covering the full range of technologies from devices to systems and networks. While many problems can be tackled by working independently within these areas, often important innovation comes from solutions that cut across such topical boundaries. Understanding device performance impacts and likewise network requirements can be essential to unlocking the critical ideas that lead to progress. View full abstract»

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  • Channel power excursions from single-step channel provisioning

    Page(s): A1 - A7
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    Steady-state power excursions arising from channel-addition wavelength-switching events are measured as a function of spectral configuration and amplifier settings in an erbium-doped-fiber-amplifier- (EDFA-) based reconfigurable optical add-drop multiplexer network, and they exhibit a maximum excursion of 4.5 dB after four spans of 40 km standard single-mode fiber and 5 EDFAs. A simple model is introduced to explain the power-coupling phenomena responsible for the power excursions. The results show that the maximum excursion is determined by the maximum mean gain difference between the existing and added channels and does not necessarily correspond to the maximum number of channels or input power change. View full abstract»

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  • Electro-absorption-based fast photonic integrated circuit sources for next network capacity scaling [invited]

    Page(s): A8 - A16
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1346 KB) |  | HTML iconHTML  

    Increasing component speed, throughput and efficiency inevitably leads to optoelectronic transmitters and receivers of more complexity, larger footprint, consumption and cost. Monolithic integration is known to help in solving these problems typical of discrete components. However, lowering of the cost, consumption and material usage must preserve high modulation performance especially while increasing the data rate. These issues are addressed by our new photonic integrated circuit technology on indium phosphide. The demonstrated laser transmitter circuits rely on electro-absorption modulators, one of the smallest and most energy-efficient electro-optic converters. By improving old and creating new component classes, this approach is expected to reduce dramatically their environmental footprint. View full abstract»

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  • Scaling low-latency optical packet switches to a thousand ports

    Page(s): A17 - A28
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    Optical packet switches that scale to thousands of input/output ports might find their application in next-generation datacenters (DCs). They will allow interconnecting the servers of a DC in a flat topology, providing higher bandwidth and lower latency in comparison with currently applied electronic switches. Using a simple analytic model that allows computing end-to-end latency and throughput, we show that optical interconnects that employ a centralized (electronic) controller cannot scale to thousands of ports while providing end-to-end latencies below 1 μs and high throughput. We therefore investigate architectures with highly distributed control. We present astrictly non-blocking wavelength division multiplexing architecture with contention resolution based on wavelength conversion. We study the packet loss probability of such architecture for different implementations of the contention resolution functionality. Furthermore, we show that the proposed architecture, applied in a short link with flow control, provides submicrosecond end-to-end latencies and allows high load operation, while scaling over a thousand ports. View full abstract»

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  • Silicon photonics for next generation FDM/FDMA PON

    Page(s): A29 - A37
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    Frequency division multiplexing/frequency division multi-access passive optical networks are shown to provide a possible solution in terms of performance, manufacturability and cost to the specification of the second next generation passive optical access systems (NG-PON2). The upstream capacity of a particular implementation is experimentally evaluated, and the implementation of the required optical network unit in silicon photonics is analyzed, as this complementary-metal-oxide-semiconductor-compatible technology is well suited for mass market applications. View full abstract»

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  • SPRINT: Scalable photonic switching fabric for high-performance computing (HPC)

    Page(s): A38 - A47
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    High-performance computing systems and datacenters will interconnect hundreds to thousands of heterogeneous general purpose or specialized cores in the future. As the number of network end-point sockets scales exponentially, the underlying communication fabric must deliver high bandwidth with low power and reduced switching complexity. While high-radix routers enable smaller diameter networks, the penalty is in increased switching complexity and router power. In this paper, we propose SPRINT (scalable photonic reconfigurable interconnect), which can scale to a large number of cores using photonic switching implemented with silicon micro-ring resonators (MRRs). MRRs are low power, high bandwidth photonic switching devices that can be arranged to function similarly to a high-radix router with reduced complexity and power. We will first show the design of a 64 core cluster using optical interconnects and electrical packet switching. To build scalable switching crossconnects, we investigate the design of 256-, 512- and 1024-socket versions of SPRINT connected to function as passive arrayed-waveguide gratings. Our proposed switching crossconnect with single and dual micro-rings minimizes the hop count to 4 for a 1024 core network while reducing the power dissipation, increasing the bandwidth and reducing the switching complexity. View full abstract»

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  • N × N coupler uniformity in a CWDM passive star home network based on multimode fiber: A time-effective calculation method

    Page(s): A48 - A58
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    Optical fiber is the most appropriate medium able to meet future requirements in terms of capacity and heterogeneity in the home network. The advantages of a passive star architecture associated with wavelength multiplexing have already been reported. For lower-cost issues, multimode fiber would be preferred, but some problems were raised related to poor uniformity of the N × N multimode coupler when using the usual coarse wavelength division multiplexing sources. An original time-effective method is proposed, based on both simulation and calculation. Many results are provided, giving a better understanding of the behavior of the N × N coupler when different types of sources are used, also taking into account improvement techniques such as offset launching or mode scrambling. View full abstract»

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  • Energy efficiency of optical transceivers in fiber access networks [invited]

    Page(s): A59 - A68
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (424 KB) |  | HTML iconHTML  

    The dramatic growth of Internet traffic is leading to a concern about the future power consumption of the Internet. Energy sustainability of communication networks is becoming a very important goal for the reduction of the global carbon footprint. As optical access networks gain more popularity, their share in the energy consumption of the data network will increase. Developing energy-efficient technologies for optical access networks is therefore crucial for the continuous scaling of the Internet. In this paper, we model the power consumption of different transceivers and demonstrate how various electronic and photonic technologies can help improve energy efficiency. We discuss the impact of different light sources and driver circuits on the transceiver power efficiency. We also show how energy efficiency is related to network topology. View full abstract»

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  • Quantum-dash mode-locked lasers for tunable wavelength conversion on a 100 GHz frequency grid

    Page(s): A69 - A76
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (446 KB) |  | HTML iconHTML  

    All-optical wavelength converters play a key role for next-generation high-bit-rate optical networks. A high-speed, simple, and compact wavelength converter can resolve contention, reduce wavelength blocking, and enable a multitude of new wavelength routing approaches. We propose the combination of a quantum-dash mode-locked laser (QD-MLL) with a frequency-selective filter to provide (two) tunable wavelength pumps for wavelength conversion of optical channels in a dual-pump four-wave-mixing (FWM) scheme. Such a converter is simple, practical, and offers a wide conversion range, modulation format transparency, and the potential for photonic integration. We examine the performance of the proposed scheme experimentally with a QD-MLL and manually tunable optical filters. Wavelength conversion is achieved via an extremely non-linear semiconductor optical amplifier (SOA), a commercial SOA with very high FWM efficiency. We achieved near -3 dB conversion efficiency across a 9.6 nm tuning range with a signal input power of -3 dBm and a pump input power of 2 dBm. We performed bit error rate (BER) measurement on a 5.6 nm conversion range and obtained error-free transmission (BER <;10-9) with less than 2 dB power penalty. View full abstract»

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  • Time resolved bit error rate analysis of a fast switching tunable laser for use in optically switched networks

    Page(s): A77 - A81
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (402 KB) |  | HTML iconHTML  

    We investigate the use of different direct detection modulation formats in a wavelength switched optical network. We find the minimum time it takes a tunable sampled grating distributed Bragg reflector laser to recover after switching from one wavelength channel to another for different modulation formats. The recovery time is investigated utilizing a field programmable gate array which operates as a time resolved bit error rate detector. The detector offers 93 ps resolution operating at 10.7 Gb/s and allows for all the data received to contribute to the measurement, allowing low bit error rates to be measured at high speed. The recovery times for 10.7 Gb/s non-return-to-zero on-off keyed modulation, 10.7 Gb/s differentially phase shift keyed signal and 21.4 Gb/s differentially quadrature phase shift keyed formats can be as low as 4 ns, 7 ns and 40 ns, respectively. The time resolved phase noise associated with laser settling is simultaneously measured for 21.4 Gb/s differentially quadrature phase shift keyed data and it shows that the phase noise coupled with frequency error is the primary limitation on transmitting immediately after a laser switching event. View full abstract»

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  • Scaling photonic packet switches to a large number of ports [invited]

    Page(s): A82 - A89
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    We review our work on optical switching architectures that allow for scaling to a large number (thousands) of ports. We explain that the complexity of the node control critically depends on the node architecture and, hence, critically impacts the end-to-end latency of the system. We introduce node architectures with highly distributed control that allow for systems with very low end-to-end latency. We present integrated devices that support such systems and we present laboratory experiments to illustrate the technical feasibility of such switching systems. View full abstract»

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  • Narrow-linewidth discrete-mode laser diodes for coherent communication applications

    Page(s): A90 - A96
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    Lasers with narrow-linewidth emission are a key component for higher-order modulation formats. We report on discrete-mode laser diodes designed for narrow-linewidth emission and demonstrate linewidths less than 80 kHz. Using these devices in quadrature phase shift keying and 16-quadrature amplitude modulation transmission setups, similar performance to that of an external cavity laser is demonstrated. View full abstract»

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  • AWGR-based optical topologies for scalable and efficient global communications in large-scale multi-processor systems

    Page(s): 651 - 662
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    In large-scale multi-processor computing systems, global communications are typically supported by an auxiliary network (e.g., IBM Blue Gene) or with hardware support in the network (e.g., NEC Earth Simulator). We explore the potential for realizing efficient global communications that can scale beyond a million processors by harnessing the unique parallelism and wavelength routing properties of optical devices. Specifically, we use an arrayed waveguide grating router (AWGR) device as the basic building block in realizing scalable global communication. The AWGR is a passive switch fabric (wavelength router) that uses multiple wavelengths to interconnect outputs and inputs by following a specific cyclic wavelength routing (permutation) pattern. We analyze different network topologies using AWGR devices for barrier synchronization and propose techniques to pick parameters of the network for a given number of processors. We compare the performance and energy consumption for barrier synchronization with what is achievable with state-of-the-art electrical networks. View full abstract»

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  • Link-layer buffering requirements and optimization of Gb/s infrared enabled devices

    Page(s): 663 - 670
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    We present an analytical model for dimensioning the buffering requirements of the link-layer in half-duplex Gb/s infrared links. Our model takes into account both physical layer parameters, including the bit-error-rate and the turnaround time of the link, and link-layer parameters, including the protocol window and frame size, in order to calculate the utilization efficiency of the infrared link as a function of the buffer size. We utilize the model to establish the buffer size that is required to achieve acceptable efficiencies for a broad range of standardized infrared link and link-layer protocol configurations. Our analysis shows that it is possible to optimize the link-layer window and frame size in order to achieve maximum efficiency for any given buffer size and link configuration, and we provide analytical relations for the buffer-constrained optimal window and frame size. View full abstract»

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  • Add/drop contention-aware RWA with directionless ROADMs: The offline lightpath restoration case

    Page(s): 671 - 680
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (320 KB) |  | HTML iconHTML  

    Directionless reconfigurable add/drop multiplexers (ROADMs) permit changing the direction of an added/dropped lightpath without manual intervention. If the ROADM is also colorless, its wavelength can be automatically reconfigured. In broadcast-and-select directionless ROADM architectures, the number of lightpaths that can be added/dropped using the same wavelength is limited by the so-called add/drop contention factor C. This is a source of light-path blocking that reduces the network capacity. A previous work investigated this aspect for the case of unprotected and 1+1 protected lightpaths. In this paper, we address the case in which lightpath restoration is the fault recovery technique in the network. We hypothesize that, using appropriate network planning, the add/drop contention effects can be mitigated. For this, we propose and investigate the add/drop contention-aware routing and wavelength assignment with lightpath restoration offline planning problem, considering colored ROADMs. To solve the problem, an effective heuristic is presented. Extensive results are reported for four reference topologies. In our tests, the reduction in the network capacity caused by add/drop contention is eliminated in practice for factors C = 2, or even C = 1 in some topologies. These results contribute to the dimensioning of directionless ROADMs. View full abstract»

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  • Converged optical network and data center virtual infrastructure planning

    Page(s): 681 - 691
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    This paper presents a detailed study of planning virtual infrastructures (VIs) over a physical infrastructure comprising integrated optical network and data center resources with the aim of enabling sharing of physical resources among several virtual operators and services. Through the planning process, the VI topology and virtual resources are identified and mapped to the physical resources. Our study assumes a practical VI demand model without any in advance global knowledge of the VI requests that are handled sequentially. Through detailed integer linear program modeling, two objective functions - one that minimizes the overall power consumption of the infrastructure and one that minimizes the wavelength utilization - are compared. Both are evaluated for the virtual wavelength path and wavelength path optical network architectures. The first objective results in power consumption savings and the two optical network architectures provide similar performances. However, the trend changes for higher load values, due to the inefficient wavelength utilization that the first objective leads to. Finally, we compare the virtual infrastructures created by the two objectives through online traffic provisioning simulations. The objective minimizing wavelength utilization results in VIs suffering higher request blocking compared to the VIs created by the objective minimizing the overall power consumption. View full abstract»

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  • Segment-based protection of multicast connections in metropolitan area optical networks with quality-of-transmission considerations

    Page(s): 692 - 702
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (341 KB) |  | HTML iconHTML  

    This paper investigates the problem of protecting multicast sessions in optical networks utilizing a novel segment-based protection heuristic algorithm called LP (level protection). The proposed scheme exhibits improved performance in terms of blocking probability compared to other traditional segment-based multicast protection schemes, especially when sharing techniques are also utilized. Furthermore, when physical layer impairments are also taken into account for the calculation of the working and protection light-trees, it is shown that the LP technique presents significant improvement in performance compared to the other commonly used protection techniques. View full abstract»

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  • Bidirectional 60 GHz RoF system with two millimeter-wave signals generated by a novel generation scheme

    Page(s): 703 - 708
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (276 KB) |  | HTML iconHTML  

    A two millimeter-wave signal generation scheme for a bidirectional 60 GHz radio-over-fiber system is theoretically analyzed and numerically verified. Three dual-electrical Mach-Zehnder modulators (MZMs) and two optical inter-leavers (OILs) are employed, and MZM1, MZM2, and MZM3 are biased at the minimum, maximum, and minimum transmission points, respectively. The two OILs and a fiber Bragg grating are used to separate the subcarriers after transmission. In the scheme, a tunable laser serves as the optical source, and two 60 GHz millimeter-wave signals with modulating data are generated to transmit diversity, and a remote local oscillator is also generated. The analytical models for transmission through a dispersive medium are confirmed by simulations. It is found that chromatic dispersion has little impact on the bit error rate performance when a narrow-linewidth laser and a noise management technique are employed. View full abstract»

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Aims & Scope

IEEE/OSA Journal of Optical Communications and Networking covers advances in the state-of-the-art of optical communications and networks.

Full Aims & Scope

Meet Our Editors

Editors-in-Chief
Patrick Iannone
  Alcatel-Lucent Bell Labs
Ori Gerstel
   Cisco Systems, Inc.