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Lightwave Technology, Journal of

Issue 3 • Date March 2007

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Displaying Results 1 - 25 of 45
  • [Front cover]

    Page(s): C1
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    Freely Available from IEEE
  • Journal of Lightwave Technology publication information

    Page(s): C2
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    Freely Available from IEEE
  • Table of contents

    Page(s): 653 - 654
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  • Capacity Scaling in a Multihost Wavelength-Striped SOA-Based Switch Fabric

    Page(s): 655 - 663
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (793 KB) |  | HTML iconHTML  

    The scaling of the capacity of a semiconductor- optical-amplifier-based switch carrying wavelength-striped data is assessed under packet timescale reconfiguration for short- reach high-capacity data interconnects. Off-the-shelf components are used with a low-complexity control layer to demonstrate high-capacity end-to-end packet routing. The impact of increasing the aggregate data rate and the number of connections made to the switch fabric is assessed in terms of the power penalty and dynamic range for a broadcast and select architecture. Studies with up to ten wavelength-multiplexed data channels with an aggregate capacity of 100 Gb/s are shown to give sufficient margin for even higher aggregate data rates and for the additional splitter stages, which would enable 8times8 connectivity in a single stage. Further increases in connectivity are anticipated with higher performance commercially available transmitters and receivers. Multipath routing is assessed with three hosts simultaneously transmitting wavelength-striped data packets over the same switch fabric to reveal a penalty in the range of 0.3-0.6 dB due to multi- path crosstalk and a modest penalty in the range of 0.4-1.2 dB that was incurred through dynamic routing. A route to terabit-per- second switch performance in a single-stage low-complexity switch fabric is identified. View full abstract»

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  • Surviving-Channel-Power Transients in Second-Order Pumped Lumped Raman Fiber Amplifier: Experimentation and Modeling

    Page(s): 664 - 672
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (279 KB) |  | HTML iconHTML  

    In this paper, the effect of addition and/or dropping of wavelength-division-multiplexed channels in an all- optical gain-clamped (AOGC) second-order (SO) pumped lumped Raman fiber amplifier (LRFA) has been investigated experimentally and analyzed by numerical simulation. Channel addition/ removal was simulated by transmitting ten signals through a counter-directionally pumped LRFA consisting of a 16-km-long dispersion-compensating fiber. The light from eight lasers was square-wave modulated at 500 Hz; power transients of the surviving channels caused by cross-gain modulation of the LRFA were monitored at the output of the amplifier. All-optical feedback loop was implemented in the form of a ring laser. Gain-clamping properties of the SO-pumped LRFA are compared with those of the first-order pumped LRFA having the same ON/OFF Raman gain. Theoretical analysis of the AOGC LRFA was based on numerical solution of coupled propagation equations for the backward propagating pump, signals, and both forward and backward propagating spectral components of amplified spontaneous emission powers. View full abstract»

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  • Full-Duplex DOCSIS/WirelessDOCSIS Fiber–Radio Network Employing Packaged AFPMs as Optical/Electrical Transducers

    Page(s): 673 - 684
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1228 KB) |  | HTML iconHTML  

    A hybrid fiber-radio access network architecture for simultaneous wireline and wireless transmissions of data-over-cable service interface specification (DOCSIS) signals is presented. An all-optical harmonic up-conversion technique using a dual-drive Mach-Zehnder modulator provides the downstream optical signal modulated not only at the intermediate frequency in the 600- to 900-MHz band for wireline transmission but also at the up-converted frequency in the 5.45- to 5.75-GHz band for wireless transmission. An InGaAsP/InGaAsP multiple-quantum-well asymmetric Fabry-Perot modulator/detector has been designed, fabricated, and packaged and has been employed in the base station (BS) as an optical/electrical transducer, simultaneously providing the functions of optical intensity modulation and photodetection. At the BS, the DOCSIS signals are recovered at the wireline and wireless frequencies for the respective feeding of a cable access network or a fixed wireless access network in a highly flexible approach. Full-duplex operation has been demonstrated for both access types in an indoor laboratory environment. In a subsequent small-scale field trial, real-life Internet traffic provided by a local community antenna television system operator has been transported over the present hybrid fiber-radio access network architecture, and simultaneous transmission of both DOCSIS and digital television signals has also been performed. View full abstract»

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  • A 10-Gb/s 1024-Way-Split 100-km Long-Reach Optical-Access Network

    Page(s): 685 - 693
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (414 KB) |  | HTML iconHTML  

    Optical-access networks have been developed to remove the access-network bandwidth bottleneck. However, the current solutions do not adequately address the network economics to provide a truly cost-effective solution. Long-reach optical-access networks introduce a cost-effective solution by connecting the customer directly to the core network, bypassing the metro network, and, hence, removing significant cost. This paper charts the design and development of a 1024-way-split 100-km 10-Gb/s symmetrical network, which experimentally proves the feasibility of long-reach optical-access networks for both the upstream and downstream transmission. View full abstract»

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  • An Architecture for TSI-Free Nonblocking Optical TDM Switches

    Page(s): 694 - 702
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (374 KB) |  | HTML iconHTML  

    One of the key elements in building a time-division- multiplexed (TDM) switch is the time slot interchange (TSI). Given the current optical switching and buffer technologies, TSI-based TDM architectures have many implementation drawbacks, including severe signal attenuation. Some studies showed that some space-time equivalence diagrams can be converted into a delay-unit-based (TSI-free) TDM. This type of architecture is attractive for optical TDM switches, but the techniques discussed in those studies are for rearrangeable switches. Many applications require nonblocking switches where adding a new connection (or a flow) will not cause rearrangement of existing connections. In this paper, we present the design principle for building strictly nonblocking delay-unit-based (TSI-free) optical TDM switches. View full abstract»

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  • All-Optical-Packet Header and Payload Separation for Unslotted Optical-Packet-Switched Networks

    Page(s): 703 - 709
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (352 KB) |  | HTML iconHTML  

    A novel all-optical header and payload separation technique that can be utilized in unslotted optical-packet-switched networks is proposed. The technique uses two modified terahertz optical asynchronous demultiplexers: One is for packet header extraction with differential modulation scheme, and the other performs a simple xor operation between the packet and its self-derived header to get the separated payload. The main virtue of this system is simple structure and low-power consumption. Through numerical simulations, the operating characteristics of the scheme are illustrated. In addition, the parameters of the system are discussed and designed to optimize the performance of the scheme View full abstract»

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  • Performance Evaluation of Tunable Channel-Selective Wavelength Shift by Cascaded Sum- and Difference-Frequency Generation in Periodically Poled Lithium Niobate Waveguides

    Page(s): 710 - 718
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (352 KB) |  | HTML iconHTML  

    We theoretically evaluate the performance of tunable channel-selective wavelength shift based on cascaded sum- and difference-frequency generation by the use of two pump lights in periodically poled lithium niobate waveguides. In double-pass configurations, the functions of wavelength add/drop and wavelength shift are easy to integrate in the same waveguide. Analysis shows that a longer waveguide more competently adapts narrower channel spacing in wavelength-division-multiplexed (WDM) systems. This wavelength shifter is flexible due to the almost separable operations of the two pumps: The channel is selected by setting the first pump, and the wavelength-shifting value is tuned by adjusting the second pump. This wavelength shifter has a very large dynamic region. For a 2.56-cm-long waveguide, the maximum dynamic region is as broad as 67 nm in a 0.4-nm channel-spacing WDM system. The dynamic region is mainly dominated by the limitation of multiple-channel crosstalk in a dense WDM system. However, it is dominated by the limitation of single-channel efficiency fluctuation in a coarse one View full abstract»

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  • 1092 Channel 2-D Array Demultiplexer for Ultralarge Data Bandwidth

    Page(s): 719 - 725
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1270 KB) |  | HTML iconHTML  

    We demonstrate 1 times 1092 channel wavelength demultiplexing with 50-GHz channel pitch and a 600-nm total bandwidth. Outputs from 1 times 40 channel arrayed waveguide gratings operating with multiple orders enter a free-space optical grating demultiplexer which separates the orders into a 2-D spot array, where the light can be coupled into discrete output fibers or operated on by a surface normal device (i.e., microelectromechanical system switch or detector array). Supercontinuum source input from 1140 to 1750 nm produced a 28 times 39 spot array at the output plane. The insertion loss for light is coupled into a single mode fiber ranged from 7 to 18 dB with less than 10-dB loss in channels between 1300 and 1750 nm. Bit-error-rate measurements show a negligible 0.1-dB power penalty at 10 GB/s View full abstract»

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  • Transient Behavior of EDFA Stages Using Pump Power Splitting or Pump Bypass Technique

    Page(s): 726 - 732
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    Power transients in optical networks impose challenging requirements on the design and control of optical amplifiers. In addition, reducing amplifier cost has become mandatory. Therefore, setups using a single pump to supply pump power to several coils of erbium-doped fibers (EDFS) have become attractive. In most cases, the so-called pump bypass technique is employed, but pump power splitting also constitutes a favorable solution. Both techniques are compared with respect to their transient behavior. The investigations focus on the characteristics of the optical setup representing the control path. Appropriate scenarios are considered to take into account the influence of feedforward and feedback control techniques. Simulation results reveal that the pump power splitting approach is favorable with respect to a feedback control, whereas there are no significant differences with respect to feedforward approaches View full abstract»

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  • Double Raman Amplified Bus Networks for Wavelength-Division Multiplexing of Fiber-Optic Sensors

    Page(s): 733 - 739
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (410 KB) |  | HTML iconHTML  

    In this paper, three different double Raman fiber bus networks are compared and demonstrated experimentally for the first time as a means of gathering information from wavelength-division-multiplexed optical sensors: the double-bus scheme, the improved double-bus configuration, and the hybrid topology. We report how these structures reduce the received amplified-spontaneous-scattering noise generated. This low-noise configuration yields signal-to-noise ratios over 43 dB and increases the number of sensors that could be multiplexed in a single structure. Furthermore, the last one enables the reutilization of the gratings' wavelengths View full abstract»

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  • A Single Etch-Step Fabrication-Tolerant Polarization Splitter

    Page(s): 740 - 746
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (730 KB) |  | HTML iconHTML  

    A tolerant single etch-step passive polarization splitter on InP/InGaAsP is designed and fabricated. The device consists of a directional coupler with a wide and a narrow waveguide. Modal birefringence of the third-order modes for transverse electric (TE) and transverse magnetic (TM) polarizations is employed to selectively couple one polarization. Tapering is applied to increase the tolerances. The devices are characterized, and the measurement results show good agreement with the beam-propagation-method simulations: a splitting ratio larger than 95% for a width range of around 100 nm and over a large wavelength range, covering at least the C-band View full abstract»

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  • Output-Noise Statistical Characterization for Digital-Phase-Demodulation Systems With Intensity-Based Input Noise

    Page(s): 747 - 756
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (725 KB) |  | HTML iconHTML  

    A large fraction of fiber-optic-sensor systems make use of interferometry in the measurement process, implying the need for demodulation to obtain the encoded signal of interest. Of great interest for sensor characterization is the performance of the demodulation scheme under the influence of noise. In this paper, we construct a very general transfer function that relates intensity-induced input noise to its phase noise realization in the output for a wide class of digital-demodulation techniques. We proceed to compute analytically a probability density function of this output noise and use this to compute low-order statistical moments of the output noise. We compare the analytical formulations with simulated data from a representative demodulation scheme used in a currently existing fiber Bragg grating (FBG) sensor system and find excellent agreement View full abstract»

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  • Dispersion Compensation Over All the Telecommunication Bands With Double-Cladding Photonic-Crystal Fiber

    Page(s): 757 - 762
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    This paper numerically describes the design of double-cladding photonic-crystal fiber (DC-PCF) for ultrabroadband compensation over all telecommunication bands (O to L), i.e., ranging from 1260 to 1625 nm. We show that an ultrabroadband compensating DC-PCF can be designed simply by considering the zero-dispersion wavelength and the relative dispersion to the slope at a particular wavelength of a conventional single-mode fiber (SMF). As a result, we reveal that the proposed DC-PCF can successfully compensate for the dispersion of a conventional SMF with an effective dispersion range of plusmn0.4 ps/nmmiddotkm over all telecommunication bands as well as provide an effective area comparable to that of conventional dispersion-compensating fiber View full abstract»

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  • Steady-State Noise Analysis of Spontaneous and Stimulated Brillouin Scattering in Optical Fibers

    Page(s): 763 - 770
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (665 KB) |  | HTML iconHTML  

    In this paper, we present a steady-state theoretical and experimental analysis of the noise resulting from spontaneous and stimulated Brillouin scattering in an optical fiber. Wave equations are derived and solved that describe the evolution of the pump and Stokes waves along the fiber. Experiments and numerical results demonstrate the validity of the theory, either when a Stokes wave is launched at the end of the fiber or when the noise in the Stokes wave is spontaneously generated View full abstract»

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  • ASE Analysis and Correction for EDFA Automatic Control

    Page(s): 771 - 778
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (665 KB) |  | HTML iconHTML  

    A theoretical model is described that can be used for calculating the amplified spontaneous emission (ASE) at the output of an optical amplifier. The technique can be used to determine the usable optical signal power at the output of an erbium-doped fiber amplifier (EDFA) operating in the constant-output-power control mode. The model was experimentally verified by automating an EDFA to operate in the constant-signal-power control mode using an ASE correction based on our model. Calculated signal-output powers were then compared to the measured values that were obtained using an optical spectrum analyzer View full abstract»

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  • Characterization of the Birefringence in Fiber Bragg Gratings Fabricated With an Ultrafast-Infrared Laser

    Page(s): 779 - 786
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (273 KB) |  | HTML iconHTML  

    The changes of birefringence in Type I-infrared (Type I-IR) and Type II-IR fiber Bragg gratings induced by an ultrafast-IR laser in SMF-28 fibers are examined after and/or during grating inscription. The gratings are then annealed at increased temperatures up to 800 degC, and their polarization properties are monitored. It is shown that the birefringence in Type I-IR gratings inscribed in hydrogen (H2)-loaded fibers is small (~10-6) and can be decayed at room temperature, while the birefringence in Type I-IR gratings inscribed in non-H2-loaded fibers is relatively higher (~10-5) and shows strong dependence on the polarization of the IR laser beam. It has the same annealing resistance as the induced index. For Type II-IR gratings, the birefringence is an order of magnitude higher than in Type I-IR gratings (~10-4) and shows strong temperature variation during annealing View full abstract»

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  • Maximizing the Transmission Performance of Adaptively Modulated Optical OFDM Signals in Multimode-Fiber Links by Optimizing Analog-to-Digital Converters

    Page(s): 787 - 798
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (350 KB) |  | HTML iconHTML  

    Based on a comprehensive theoretical model of a recently proposed novel technique known as adaptively modulated optical orthogonal frequency-division multiplexing (AMOOFDM), investigations are undertaken into the impact of an analog-to-digital converter involved in the AMOOFDM modem on the transmission performance of AMOOFDM signals in unamplified intensity-modulation and direct-detection (IMDD) multimode-fiber (MMF)-based links. It is found that signal quantization and clipping effects are significant in determining the maximum achievable transmission performance of the AMOOFDM modem. A minimum quantization bit value of ten and optimum clipping ratio of 13 dB are identified, based on which, the transmission performance is maximized. It is shown that 40-Gb/s-over-220-m and 32-Gb/s-over-300-m IMDD-AMOOFDM signal transmission at 1550 nm with loss margins of about 15 dB is feasible in the installed worst case 62.5-mum MMF links having 3-dB effective bandwidths as small as 150 MHz middot km. Meanwhile, excellent performance, robustness to fiber types, and variation in launch conditions and signal bit rates is observed. In addition, discussions are presented of the potential of 100-Gb/s AMOOFDM signal transmission over installed MMF links View full abstract»

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  • Optimization of Fiber Bragg Gratings Using a Hybrid Optimization Algorithm

    Page(s): 799 - 802
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (368 KB) |  | HTML iconHTML  

    A new hybrid optimization algorithm is proposed for the design of a fiber Bragg grating (FBG) with complex characteristics. The hybrid algorithm is a two-tier search that employs a global optimization algorithm (i.e., the Staged Continuous Tabu Search (SCTS) algorithm) and a local optimization method (i.e., the Quasi-Newton method). First, the SCTS global optimization algorithm is used to find a "promising" FBG structure that has a spectral response as close as possible to the targeted spectral response. Then, a local optimization method, namely, the Quasi-Newton method, is applied to further optimize the promising FBG structure obtained from the SCTS algorithm to arrive at a targeted spectral response. To demonstrate the effectiveness of the method, the design and fabrication of an optical bandpass filter are presented View full abstract»

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  • A Fiber Splicing-Plane-Inspection Technique Using Lens–Fiber Interference for the Cascaded Fiber Fabrication

    Page(s): 803 - 810
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1455 KB) |  | HTML iconHTML  

    In this paper, a novel inspection technique for the cascaded fiber fabrication is proposed to improve the coupling performance of such fibers. Instead of using a direct-monitoring method, an indirect technique with the help of the ray tracing and the lens-fiber interference is used. By calculating the optical-path length of the light rays passing through the fiber, the interference fringes and light intensity can be counted. Then, the splicing plane of the cascaded fiber can be determined by observing the difference between the two fiber sections. Simulations and experiments have been performed to find the splicing plane. Finally, the accuracy of fabrication can be improved from 10 to about 1 mum; thus, the coupling loss due to the fabrication process can be reduced View full abstract»

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  • Calculating Dispersion Derivatives in Fiber-Optic Design

    Page(s): 811 - 819
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (314 KB) |  | HTML iconHTML  

    Maxwell's equation for modeling the guided waves in a circularly symmetric fiber leads to a family of partial differential-equation-eigenvalue systems. In fiber design, one would like to determine the index profile, which is involved in Maxwell's equation so that certain optical properties, which sometimes involve derivatives of the eigenvalues, are satisfied. In this paper, we will discuss how to determine derivatives of the eigenvalue problem and the gradients of the dispersion with respect to design parameters in the model View full abstract»

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  • Dispersion Measurement in Optical Fibers Using Supercontinuum Pulses

    Page(s): 820 - 824
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (219 KB) |  | HTML iconHTML  

    The chromatic dispersion of an optical fiber is measured using a time-of-flight technique, based on temporally and spectrally resolving a dispersed broadband pulse, on which a spectral fringe pattern has been imposed using an etalon. The technique employs broadband supercontinuum radiation, generated by launching picosecond pulses from a fiber laser into a photonic-crystal fiber. It allows the dispersion of highly dispersive optical fibers and components to be measured with a high spectral resolution over a wide wavelength region. The technique is demonstrated by measuring the dispersion of a dispersion-compensating module over its entire 400-nm transmission band with a subnanometer spectral resolution View full abstract»

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  • Multiplexing of Fiber-Optic Long-Period Grating-Based Interferometric Sensors

    Page(s): 825 - 829
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (247 KB) |  | HTML iconHTML  

    Two long-period gratings (LPGs) fabricated in series in an optical fiber form a Mach-Zehnder interferometer, producing a sinusoidal channelled spectrum within the characteristic LPG attenuation bands, which has the appearance of an interference fringe pattern. The phase of the fringes is sensitive to changes in the surrounding environmental parameters, such as refractive index. Fabrication of a number of identical cascaded LPG pairs with different separations produces independent fringe patterns of different frequencies within the attenuation bands. The application of basic Fourier techniques to analyze the transmission spectrum allows the phase of each fringe pattern to be determined independently, facilitating the differentiation of external effects acting on each interferometer 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