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Lightwave Technology, Journal of

Issue 8 • Date Aug. 2006

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Displaying Results 1 - 25 of 39
  • Journal of Lightwave Technology publication information

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

    Page(s): 2965 - 2966
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    Freely Available from IEEE
  • ARTEMIS: 40-gb/s all-optical self-routing node and network architecture employing asynchronous bit and packet-level optical signal processing

    Page(s): 2967 - 2977
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    A 40-Gb/s asynchronous self-routing network and node architecture that exploits bit and packet level optical signal processing to perform synchronization, forwarding, and switching in the optical domain is presented. Optical packets are self-routed on a hop-by-hop basis through the network by using stacked optical tags, each representing a specific optical node. Each tag contains necessary control signals for configuring the node-switching matrix and forwarding each packet to the appropriate outgoing link and onto the next hop. In order to investigate the feasibility of their approach physical-layer simulations are performed, modeling each optical subsystem of the node showing acceptable signal quality and end-to-end bit error rates. In the All-optical self-RouTer EMploying bIt and packet-level procesSing (ARTEMIS) control plane, a timed/delayed resource reservation-based signaling scheme is employed combined with a load-balancing feedback-based contention-avoidance mechanism that can guarantee a high performance in terms of blocking probability and end-to-end delay View full abstract»

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  • Characterization of 1/spl times/N broadcast and 2/spl times/N multicast packet switching using active-vertical-coupler-based optical crosspoint switch

    Page(s): 2978 - 2985
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    This paper reports the expansion of a novel optical multicast scheme to 1-to-4 and 2-to-4 configurations using an active-vertical-coupler (AVC)-based optical crosspoint switch (OXS) matrix. A 1-to-4 broadcast experiment has been carried out first, with only 0.5 dB excess loss per signal split. Input signals with two wavelengths are then fed into one row of OXS to investigate the effect of wavelength-division multiplexing on the 1-to-4 multicast switching. Finally, combining both, the expanded 2-to-N multicast is also achieved with an N value up to 4. The switching characteristics, switched signal quality, and optical signal-to-noise ratio (OSNR) have been investigated in different configurations. Power penalties of less than 4.5 dB are found in worst case switched signals in the 2-to-4 configuration. Slow OSNR degradation in line with previous prediction is also observed. The measured results confirm the excellent multicast switching characteristics nearly free from power splitting loss in this device View full abstract»

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  • Blocking probability of a preemption-based bandwidth-allocation scheme for service differentiation in OBS networks

    Page(s): 2986 - 2993
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    For the next generation optical Internet, optical burst switching (OBS) is considered as a promising solution to exploit the capacity provided by wavelength-division-multiplexing technology. In this paper, the authors analyze preemption-based bandwidth-allocation (PBA) scheme for supporting service differentiation in OBS networks. They first propose the mathematical analysis of burst blocking probability (BBP) for a general case of probabilistic wavelength-preemption algorithm. The BBP of a new arrival burst for a K-channel N-class system is presented. They then apply this model to PBA. The results of analytical loss model are investigated and compared with simulations. The simulation results validate their analytical model and show that a BBP can be controlled for different service classes with the PBA scheme View full abstract»

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  • Time-slot assignment using optical buffer with a large variable delay range based on AVC crosspoint switch

    Page(s): 2994 - 3001
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    Time-slot assignment (TSA) functions including time-slot interchange and serial-to-parallel and parallel-to-serial conversions, and optical compressor are investigated using an optical buffer with a large variable delay range based on active vertical coupler crosspoint switch. The variable delay range could be achieved from 1 to 999 time slots in the proposed scheme, and correspondingly, the length of time slot is flexible. It is demonstrated that the experiments could be performed even at a data rate of 10 Gb/s with power penalties of about 1.5 and 5.6 dB compared with back-to-back when the packets pass through two buffers and one buffer nine times View full abstract»

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  • Adaptive path selection in OBS networks

    Page(s): 3002 - 3011
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    In this paper, the authors investigate the concept of adaptive path selection in optical burst-switched networks and its potential to reducing the overall burst drop probability. Specifically, the authors assume that each source maintains a (short) list of alternate paths to each destination and uses information regarding the recent congestion status of the network links to rank the paths; it then transmits bursts along the least congested path. The authors present a suite of path selection strategies, each utilizing a different type of information regarding the link congestion status, and evaluate them using simulation. The results demonstrate that, in general, adaptive path selection outperforms shortest path routing, and, depending on the path strategy involved, the network topology, and the traffic pattern, this improvement can be significant. A new framework for the development of hybrid (or meta) path selection strategies, which make routing decisions based on a weighted combination of the decisions taken by several independent path selection strategies, has been presented. This paper presents two instances of such hybrid strategies, i.e., 1) one that assigns static weights and 2) one that dynamically adjusts the weights based on feedback from the network; it has been shown that these strategies can further improve the overall burst drop probability in the network View full abstract»

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  • Experimental demonstration of OCDMA traffic over optical packet switching network with hybrid PLC and SSFBG en/decoders

    Page(s): 3012 - 3020
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    The transmission of coherent optical code division multiple access (OCDMA) traffic over optical-code-based optical packet switching (OPS) network has been proposed and successfully demonstrated in experiment. Full function of the OPS node has been successfully demonstrated in the experiment with coherent OCDMA traffic. A hybrid using planar lightwave circuit and superstructured fiber Bragg grating en/decoder for packet label and OCDMA-payload encoding/decoding has been verified as well. Error-free (<10-12) transmissions have been achieved for the 10- and 40-Gb/s payload data and up to two OCDMA channels View full abstract»

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  • High-repetition-rate pulsed-pump fiber OPA for amplification of communication signals

    Page(s): 3021 - 3027
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    The use of a high-repetition-rate pulsed-pumped fiber optical parametric amplifier (OPA), followed by a narrow optical filter for transparent signal amplification, was proposed. Theory and simulations predict larger gain and gain bandwidth compared to a continuous-wave pump with the same average power. Experimentally, when using a pump with 0.63 W of average power in a 500-m-long highly nonlinear fiber, the gain increased from 19.7 to 29.2 dB, and the bandwidth increased when a CW pump was changed to one that is modulated by a 20-GHz cosine-squared function. Clear eye openings were demonstrated for the amplification of a 10-Gb/s NRZ signal, with a power penalty of 1.5 dB View full abstract»

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  • Simultaneous all-optical frequency downconversion technique utilizing an SOA-MZI for WDM radio over fiber (RoF) applications

    Page(s): 3028 - 3034
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    Simultaneous all-optical frequency-downconversion technique utilizing a semiconductor optical amplifier Mach-Zehnder interferometer (SOA-MZI) is experimentally demonstrated, and its application to a wavelength-division-multiplexing (WDM) radio over fiber (RoF) uplink is proposed. The conversion efficiencies from 22.5 (fRF) to 2.5 GHz (fIF=fRF-2fLO) are in the range from 1.5 to 3 dB for the optical RF wavelength between 1548 and 1558 nm. Error-free simultaneous all-optical frequency downconversion of the two WDM RoF upstream channels that carry 155-Mb/s differential phase-shift keying data at 22.5 GHz to an optical intermediate frequency signal having the frequency of 2.5 GHz with the power penalty less than 0.1 dB at the bit error rate of 10-8 is achieved View full abstract»

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  • A study on the wavelength conversion and all-optical 3R regeneration using cross-absorption modulation in a bulk electroabsorption modulator

    Page(s): 3035 - 3044
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    A 40-Gb/s 3R regenerator with a two-ring injection mode-locked fiber laser as the clock recovery and an electroabsorption modulator (EAM) as the reshaping optical decision gate is proposed and demonstrated. The cross-absorption modulation effect in a bulk EAM was also numerically modeled. Using this model, both the shape and the extinction ratio of the optical decision gate are optimized. The model is also employed to investigate the tolerance of the timing jitter, the chromatic dispersion, and the polarization mode dispersion of an all-optical 3R regenerator based on a bulk EAM decision gate. The operation margin of the 3R regenerator is presented. The theoretical results agree well with the experimental results View full abstract»

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  • Dynamic properties of FP-LD transmitters using side-mode injection locking for LANs and WDM-PONs

    Page(s): 3045 - 3058
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    In this paper, the dynamic properties of Fabry-Perot laser diode (FP-LD) transmitters using side-mode injection locking, which are intended to be applied in wavelength-division-multiplexed passive optical networks (WDM-PON) and local area networks (LANs), have been investigated. Both the direct modulation properties and wavelength switching properties of the transmitters have been clarified theoretically and experimentally, as well as the important direct modulation characteristics, such as injection power dependence, side-mode dependence, and wavelength detuning dependence. To confirm the transmission ability, fundamental transmission experiments of the transmitters in both continuous and discontinuous injection cases have been made. The experiments clarified that the error-free transmission was possible in both cases. Falling and rising times during wavelength switching actions in LAN applications have been calculated and measured. A high-speed switching method was proposed in this paper, and the effectiveness of the proposed method has been confirmed theoretically and experimentally View full abstract»

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  • Phase-induced intensity noise in digital incoherent all-optical tapped-delay line systems

    Page(s): 3059 - 3072
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    In this paper, the authors analyze conditions under which they can be certain on the intensity addition of a given device, such as tapped-delay lines, used in digital incoherent all-optical communication systems. A general expression for phase-induced intensity noise that is applicable to all types of semiconductor lasers is derived by defining an optical self-SNR expression that can be used to analyze and measure phase-induced intensity noise. The result shows that in order to have a minimal phase-induced intensity noise in most digital optical incoherent systems, a large optical self-SNR, e.g., 20 dB or more, is needed. This in turn is shown to place a limit on the maximum rate of processing in a typical incoherent optical system even neglecting the bandwidth limitation of the photodetector. Furthermore, it is shown that the maximum rate of processing depends on the laser autocorrelation function and laser coherence time View full abstract»

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  • Maximum-likelihood sequence detection with closed-form metrics in OOK optical systems impaired by GVD and PMD

    Page(s): 3073 - 3087
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    This paper thoroughly investigates the maximum-likelihood sequence detection (MLSD) receiver for the optical ON-OFF keying (OOK) channel in the presence of both polarization mode dispersion and group velocity dispersion (GVD). A reliable method is provided for computing the relevant performance for any possible value of the system parameters, with no constraint on the sampling rate. With one sample per bit time, a practically exact expression of the statistics of the received samples is found, and therefore the performance of a synchronous MLSD receiver is evaluated and compared with that of other electronic techniques such as combined feedforward and decision-feedback equalizers (FFE and DFE). It is also shown that the ultimate performance of electronic processing can be obtained by sampling the received signal at twice the bit rate. An approximate accurate closed-form expression of the receiver metrics is also identified, allowing for the implementation of a practically optimal MLSD receiver View full abstract»

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  • Fiber-optic parametric amplifiers in the presence of polarization-mode dispersion and polarization-dependent loss

    Page(s): 3088 - 3096
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    Polarization-mode dispersion (PMD) and polarization-dependent loss (PDL) associated with various optical components affect the quality of pump beams even before they enter a fiber-optic parametric amplifier (FOPA). A vector theory of the underlying four-wave mixing process is developed to study the impact of PMD and PDL on the amplification of signal and idler fields. It is shown that the use of high-quality polarizers just before the input end of the fiber can improve the performance of a dual-pump parametric amplifier considerably View full abstract»

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  • The effect of strong inline filtering on the amplitude jitter in long optical systems

    Page(s): 3097 - 3102
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    The accumulation of amplitude jitter in ultralong-haul (ULH) systems deploying strong optical filters is studied. It is shown that in such systems that operate with nonsoliton waveforms, the selective inclusion of filters may lead to the enhancement or suppression of amplitude noise accumulation, depending on the filter's positioning. This paper explains the improvement in performance that was demonstrated experimentally in a 60-span 12.5-Gb/s system with 12 periodically positioned bandlimited dynamic gain equalizers (DGE) (Optical Fiber Communication Conf., 2005). It is also shown that the same noise suppression as in (Optical Fiber Communication Conf., 2005) achieved by such a system can be achieved with as few as two strong filters if their positioning is properly optimized View full abstract»

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  • Experimental multiuser quantum key distribution network using a wavelength-addressed bus architecture

    Page(s): 3103 - 3106
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    A six-user quantum key distribution network implemented on a bus topology is experimentally demonstrated. The network employs the BB84 protocol to transmit cryptographic keys encoded unto the phase states of highly attenuated laser light to distances of up to 31 km in a standard telecommunication-grade fiber. Each user on the network is assigned a unique wavelength for communication with the network server at a time. The measured quantum bit error rate and sifted key rate compare favorably with theoretical results View full abstract»

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  • 107-gb/s optical signal generation using electronic time-division multiplexing

    Page(s): 3107 - 3113
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    This paper reports the first optical transmitter implementations operating at a serial bit rate of 107 Gb/s using solely electronic time-division multiplexing. Two methods to overcome modulator bandwidth limitations are proposed and demonstrated: low-bandwidth optical duobinary modulation and integrated optical equalization. Both transmitters are characterized in terms of bit error ratio and chromatic dispersion tolerance View full abstract»

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  • Quantum key distribution by a free-space MIMO system

    Page(s): 3114 - 3120
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    Quantum key distribution (QKD) systems for use in future free-space optical communication links restrict communication to a low bit rate. In this paper, increasing the QKD bit rate using a communication system that includes a multiple-input-multiple-output quantum key distribution (MQKD) is proposed. Such a system can enable a number of receivers to communicate simultaneously with a number of transmitter elements, which consequently increases the overall QKD bit rate. However, due to scattering and turbulence in the atmospheric channel, this method may introduce interference effects when a photon transmitted from one transmitter element reaches the wrong detector element in the receiver. These interference effects reduce the system bit rate and increase the quantum bit error rate. A novel mathematical model for analyzing the effect of crosstalk and interference on the MQKD system performance is derived. The results of the analysis indicate that atmospheric effects impair performance. In order to mitigate the atmospheric effect, using several wavelengths simultaneously is suggested. Criteria to define the number of wavelengths that are required to achieve a given performance are also provided View full abstract»

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  • DS-OCDMA encoder/decoder performance analysis using optical low-coherence reflectometry

    Page(s): 3121 - 3128
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (333 KB) |  | HTML iconHTML  

    Direct-sequence optical code-division multiple-access (DS-OCDMA) encoder/decoder based on sampled fiber Bragg gratings (S-FBGs) is characterized using phase-sensitive optical low-coherence reflectometry (OLCR). The OLCR technique allows localized measurements of FBG wavelength and physical length inside one S-FBG. This paper shows how the discrepancies between specifications and measurements of the different FBGs have some impact on spectral and temporal pulse responses of the OCDMA encoder/decoder. The FBG physical lengths lower than the specified ones are shown to affect the mean optical power reflected by the OCDMA encoder/decoder. The FBG wavelengths that are detuned from each other induce some modulations of S-FBG reflectivity resulting in encoder/decoder sensitivity to laser wavelength drift of the OCDMA system. Finally, highlighted by this OLCR study, some solutions to overcome limitations in performance with the S-FBG technology are suggested View full abstract»

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  • Fast single-mode characterization of optical fiber by finite-difference time-domain method

    Page(s): 3129 - 3136
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    Usually, although not always, manufacturers producing optical fiber state that the functioning will be single mode in most cases without specifying the wavelengths to be worked with. A rapid method of light simulation within the optical fibers was developed for a single-mode characterization, which avoids errors and problems in transmitting the signals through the fiber. The method was validated with two optical fibers, in which the intensity patterns are well known in theory, and a rather good fit between the theoretic intensity curves at the endface of the fibers was achieved. In order to characterize the monomodal regime, the method was applied to two optical fibers with different refractive-index profiles, using the finite-difference time-domain (FDTD) for the body of revolution (BOR) View full abstract»

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  • Rayleigh and Mie scattering in polymer optical fibers

    Page(s): 3137 - 3146
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    In this article, the influence of Rayleigh and Mie scattering, which are the main causes of mode mixing in polymer optical fibers (POFs), is investigated. Measurement results obtained from a variety of different POF types ranging from standard POF, high-temperature POF, up to custom-made POF are presented. These measurements are compared to theoretical results obtained from a simplified scattering model. By comparing both results, the contribution of the different scattering sources and mechanisms is characterized independently View full abstract»

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  • Bending characteristics of fiber long-period gratings with cladding index modified by femtosecond laser

    Page(s): 3147 - 3154
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    A femtosecond laser has been used to asymmetrically modify the cladding of fiber containing long-period gratings. Following modification, devices in single-mode fiber are shown to be capable of sensing the magnitude and direction of bending in one plane by producing blue and red wavelength shifts depending upon the orientation of the bend. The resulting curvature sensitivities were -1.62 and +3.82 nmmiddotm. Devices have also been produced using an elliptical core fiber to study the effects of the cladding modification on the two polarization eigenstates. A cladding modification applied on the fast axis of the fiber is shown to affect the light in the fast axis much more significantly than the light in the orthogonal state; this behavior may ultimately lead to a sensor capable of detecting the direction of bending in two dimensions for applications in shape sensing View full abstract»

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  • Group velocity matching of multimode microstructure optical fibers

    Page(s): 3155 - 3161
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    Group velocity matching is a key to the performance of multimode microstructure fibers. Simulations show that only partial matching is achieved using an intuitive graded-hole strategy, but that the usual velocity-matching limit can be achieved by numerically optimizing designs. These results demonstrate the perturbative multipole numerical method and are a step toward improved strategies for achieving high-performance microstructure fibers for a multimode transmission View full abstract»

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  • Far-field radiation of optical fibers with tapered end

    Page(s): 3162 - 3168
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    In this paper, an accurate model of the far-field radiation of a tapered optical fiber, which is widely used in communication optics and biomedical tomography, is presented. The authors first analyze the far field that is radiated from the normally cut fiber then extend the model to a fiber with a tapered end by considering the different phase contributions of the emitted rays. The proposed technique shows the effects of the cut with a view of obtaining a high efficiency both in coupling and radiation pattern characteristics 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