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Lightwave Technology, Journal of

Issue 7 • Date April1, 2008

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  • Table of contents

    Publication Year: 2008 , Page(s): 741
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  • Using Dynamic Control Frames to Reduce Packet Delays in Transceiver Array-Based Single-Hop WDM Networks

    Publication Year: 2008 , Page(s): 742 - 755
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (674 KB) |  | HTML iconHTML  

    This paper considers transceiver array-based single-hop wavelength division multiplexing (WDM) networks with reservation-based packet scheduling algorithms. In reservation-based packet scheduling algorithms for single-hop WDM networks, one or more of the wavelengths are used as control channels for transmitting reservation information. Time on a control channel is divided into control frames and each control frame is further divided into control slots. Each node is usually assigned a dedicated control slot in each control frame. Before transmitting a data packet, a node sends a control packet in a control slot to all other nodes to reserve a data slot. This paper proposes to adjust the lengths of the control frames dynamically according to the loads of the nodes by removing unused control slots. A dynamic control frame structure with variable number of control slots is proposed. A method is devised to enable the nodes in the network to dynamically acquire and release control slots depending on their loads such that the control frames include only necessary control slots for those nodes that have or potentially have data packets to send. Therefore, the delays for transmitting control packets and data packets can be reduced. Dynamically adjusting the lengths of the control frames is able to reduce the delays for transmitting control packets and data packets when the network load is light to medium or the traffic pattern is moderately or highly nonuniform; however, it introduces extra overhead in each control frame such that the length of the control frame may become larger than the size of the control frame in the fixed control frame structure resulting in higher mean packet delay when the load of the network is heavy and the traffic pattern is uniform or nearly uniform. Therefore, this paper further proposes a hybrid fixed and dynamic scheme that dynamically employs the fixed control frame scheme or the dynamic control frame scheme depending on the loads of the nodes- . The performance of the proposed hybrid scheme is studied via simulations. Our simulation results show that the hybrid scheme is able to dynamically choose the better of the fixed and dynamic control frame schemes such that it yields the lowest mean packet delay for the entire range of network loads and traffic patterns. View full abstract»

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  • Fair Bandwidth Allocation Using Effective Multicast Traffic Share in TDM-PONs

    Publication Year: 2008 , Page(s): 756 - 767
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1017 KB) |  | HTML iconHTML  

    In this paper, the effects of optical traffic-sharing on the performance of multicast video delivery in terms of the efficiency of bandwidth allocation and the fairness of link-sharing are discussed for the downstream direction of a time-division-multiplexed passive optical network (TDM-PON). We analyze the practical issues associated with multicast packet switching and transmission control in a TDM-PON and also propose a fair bandwidth allocation mechanism, called share-based proportional bandwidth allocation (S-PBA), to effectively support multicast services. In order to provide an optical network unit with a fair amount of link bandwidth and high throughput independent of traffic type, S-PBA arbitrates the amount of unicast timeslot by using effective multicast traffic share, which is determined based on multicast traffic load distribution and traffic-sharing density. Analytic and simulation results clearly validate the effectiveness of the proposed mechanism. This work is applicable to multicast video delivery or multicast traffic transmission in general, such as voice traffic, or a combination of both in the case of video conferencing, for example. View full abstract»

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  • Modeling of a Time-Spreading OCDMA System Including Nonperfect Time Gating, Optical Thresholding, and Fully Asynchronous Signal/Interference Overlapping

    Publication Year: 2008 , Page(s): 768 - 776
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (737 KB) |  | HTML iconHTML  

    We present an extended theoretical model for time-spreading optical code-division multiple-access (OCDMA) coherent systems. We have updated well-known model to evaluate multiuser interference to include arbitrary encoded/decoded chip shape, receiver transfer function, and optical thresholding before detection. Full asynchronous regime is also assumed to exploit statistical benefits over the dominant primary beat noise. The model provides clear improvements in terms of number of users and required intercodes crosstalk, leading to more feasible OCDMA systems. View full abstract»

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  • Demonstration of an Integrated LiNbO _3 Synchronized Double Phase Modulator and Its Application to Dual-Pump Fiber Optical Parametric Amplifiers and Wavelength Converters

    Publication Year: 2008 , Page(s): 777 - 781
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (765 KB) |  | HTML iconHTML  

    We report the fabrication of an integrated LiNbO3 Y-junction synchronized double phase modulator fully packaged for RF-application up to 40 GHz. This optical modulator allows for delivering simultaneously counter-phase high-speed modulation and coupling for two input channels. It was designed for application to fiber-optical parametric amplifier and wavelength converters for suppressing idler spectral broadening and signal gain distortion caused by phase modulation itself. With this component, Idler spectral broadening suppression is experimentally demonstrated over all the parametric gain band of a two-pump parametric amplifier operating in the 1.55-mum region. In addition, we present a useful technique for straightforward and full coupling of the pumps and the signal. View full abstract»

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  • Figure-of-Merit of Dispersion Compensating Devices Based on Chirped Bragg Gratings

    Publication Year: 2008 , Page(s): 782 - 790
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (291 KB) |  | HTML iconHTML  

    A promising technology for chromatic dispersion compensation in fiber communication networks are modules based on chirped Bragg gratings (DCM). Imperfections in the Bragg grating, however, give rise to a noise-like ripple in the phase characteristics of the DCM, which causes extra system penalty. In this paper, we derive an analytic formula that calculates an upper bound of the eye-opening penalty caused by a DCM in a transmission link with no optical amplifiers and with a chirp free NRZ optical signal. The primary use of this formula is as a quickly calculated quality measure (figure-of-merit) of the phase ripple characteristics of DCMs. It is shown that the difference in as given by the formula and obtained from simulation calculations is considerable smaller than given by other formulas found in the literature. View full abstract»

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  • Mathematical Modeling as an Accurate Predictive Tool in Capillary and Microstructured Fiber Manufacture: The Effects of Preform Rotation

    Publication Year: 2008 , Page(s): 791 - 798
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (664 KB) |  | HTML iconHTML  

    A method for modeling the fabrication of capillary tubes is developed that includes the effects of preform rotation, and is used to reduce or remove polarization mode dispersion and fiber birefringence. The model is solved numerically, making use of extensive experimental investigations into furnace temperature profiles and silica glass viscosities, without the use of fitting parameters. Accurate predictions of the geometry of spun capillary tubes are made and compared directly with experimental results, showing remarkable agreement and demonstrating that the mathematical modeling of fiber drawing promises to be an accurate predictive tool for experimenters. Finally, a discussion of how this model impacts on the rotation of more general microstructured optical fiber preforms is given. View full abstract»

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  • Mode-Locking in a Semiconductor Fiber Laser Using Cross-Absorption Modulation in an Electroabsorption Modulator and Application to All-Optical Clock Recovery

    Publication Year: 2008 , Page(s): 799 - 806
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (464 KB) |  | HTML iconHTML  

    We demonstrate the use of cross-absorption modulation in an electroabsorption modulator to actively mode-lock a semiconductor fiber laser at 10 GHz. The laser cavity also comprises a linearly chirped fiber Bragg grating to obtain wavelength tunable operation based on the dispersion tuning approach. The laser exhibits uniform output pulse characteristics throughout the tuning range. We also investigate the impact of using different types of optical pump signals on the output pulses. Finally, we demonstrate the application of the mode-locked laser for all-optical clock recovery. View full abstract»

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  • Improving the Performance of Sampled-Grating DBR Laser-Based Analog Optical Transmitters

    Publication Year: 2008 , Page(s): 807 - 815
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (565 KB) |  | HTML iconHTML  

    In this paper, the available analog link performance of integrated transmitters containing a sampled-grating distributed Bragg reflector laser, a semiconductor optical amplifier, and a modulator is evaluated. It is found that to provide a link gain and a low-noise figure, an RF preamplifier is required, and for this reason, spurious-free dynamic range (SFDR) including a preamplifier has been evaluated. An SFDR of 110-dBHz2/3, a noise figure of 5.4 dB, and link gain of 6.9 dB at 5 GHz is obtained. It is further investigated how link SFDR can be improved by linearization techniques. Two novel approaches are proposed and demonstrated: first, predistortion by extraction of nonlinear components from an integrated second modulator exposed to the same wavelength, optical power and temperature for matched nonlinear terms; second, a novel linearized modulator configuration balancing electroabsorption and Mach-Zehnder modulation that can reach a null for both second- and third-order intermodulation products at a single bias point. View full abstract»

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  • Optical Data Link Employing Organic Light-Emitting Diodes and Organic Photodiodes as Optoelectronic Components

    Publication Year: 2008 , Page(s): 816 - 823
    Cited by:  Papers (12)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1350 KB) |  | HTML iconHTML  

    An optical interconnect solely using organic optoelectronic components is presented. The data link is based on an organic light-emitting diode as the transmitter and an organic photodiode as the receiver. Light is transmitted via a polymer optical fiber coupled to the active components. A digitized audio signal based on the Sony/Philips Digital Interface Format standard at a signal bit rate of 2.8224 Mbit/s (44.1-kHz sampling frequency) is successfully transmitted. View full abstract»

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  • Coupled Optoelectronic Oscillation via Fundamental Mode-Locking in a Composite-Cavity Electro-Optic Microchip Laser

    Publication Year: 2008 , Page(s): 824 - 831
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1341 KB) |  | HTML iconHTML  

    Composite-cavity electro-optic microchip lasers have been proposed as a source for high-speed, low-noise microwave and optical signals. Such signals can be produced from a single short-cavity laser using the coupled optoelectronic oscillation architecture, but strict control of the cavity longitudinal modes must be maintained to achieve fundamental mode-locking. The mechanism for this control is studied analytically and it is determined that the Lorentzian gain approximation does not predict nonadjacent modal effects in short-cavity lasers. A modification is presented which can explain these effects. Experimentally, the modal structure of an adjustable short-cavity laser is investigated and the results are consistent with the revised model. Finally, the results of the theory are used to design an optimized cavity geometry that is used to successfully demonstrate FM mode-locking and coupled optoelectronic oscillation at 20 GHz using a Nd:YVO4/MgO:LiNbO3 prototype. View full abstract»

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  • Continuous and Damped Vibration Detection Based on Fiber Diversity Detection Sensor by Rayleigh Backscattering

    Publication Year: 2008 , Page(s): 832 - 838
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (886 KB) |  | HTML iconHTML  

    An optical fiber vibration sensor based on a polarization diversity scheme has been developed to study structural vibration properties under external disturbance. The polarization diversity scheme has improved signal-to-noise ratio (SNR) by over 13 dB with capability of detection frequency of sub-hertz to tens of kilo- hertz. The minimum dynamic strain we have detected is 3 nepsiv, and the SNR of the sensor is >37 dB without any averaging. For the first time, Rayleigh backscattering has been utilized to detect continuous and damped vibration generated by a piezo fiber stretcher and vibrating cantilever with a frequency range of sub-hertz to 16 kHz. We also use this sensor and polarization analyzer to characterize the polarization state change and phase shift of the piezo fiber stretcher in transmission and Rayleigh backscattering up to kilohertz frequency, both results agrees quantitatively. View full abstract»

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  • Design and Modeling of a Nanomechanical Sensor Using Silicon Photonic Crystals

    Publication Year: 2008 , Page(s): 839 - 846
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (892 KB) |  | HTML iconHTML  

    Conventionally a line defect in the photonic crystal (PhC) is used to create a waveguide for light propagation through the PhC. A PhC based filter is designed by introducing micro-cavities within the line defect so as to form the resonant bandgap structure for PhC. Such a PhC waveguide (PhCWG) filter shows sharp resonant peak in output wavelength spectrum. We proposed a suspended silicon bridge structure comprising this PhCWG filter structure. Since the output resonant wavelength is sensitive to the shape of air holes and defect length of the micro-cavity. Shift of the output resonant wavelength is observed for suspended PhCWG beam structure under particular force loading. In other words, the induced strain modifies the shape of air holes and the spacing among them. Such an effect leads to shift of resonant wavelength. Under optical detection limitation of 0.1 nm for resonant wavelength shift, the sensing capability of this nanomechanical sensor is derived as that vertical deformation is 20-25 nm at the center and the smallest strain is 0.005% for defect length. This innovative design conceptualizes a new application area for PhCs, i.e., the nanometer-scale physical sensors for strains and forces. View full abstract»

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  • Noise Figure of Silicon Raman Amplifiers

    Publication Year: 2008 , Page(s): 847 - 852
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (386 KB) |  | HTML iconHTML  

    The noise figure of silicon Raman amplifiers in the presence of nonlinear losses is calculated. The impact of two-photon absorption (TPA) and free-carrier scattering on the noise figure is quantified using the quantum formulation of the Langevin approach. It is found that TPA-induced free-carrier loss degrades the noise figure by an amount that depends on the carrier lifetime. For example, in a 1-cm-long waveguide pumped at 200 MW/cm2, the noise figure is 5.2 dB for a lifetime of tau = 1.6 ns and is reduced to 3.7 dB for tau = 0.1 ns. The reduction in the noise figure along with a concomitant increase in Raman gain from 2 to 8 dB suggests that lifetimes on the order of 0.1 ns or less are needed to create a useful silicon Raman amplifier that operates in the continuous-wave mode. It is also shown that in devices that use a p-n junction for carrier sweep-out, the screening of the junction field by generated free carriers results in a sharp increase in the noise figure at high-pump intensities. These results apply to operation in the near-infrared communication wavelengths. For mid-infrared wavelengths above the two photon absorption band-edge (2.3 nm), the absence of TPA and pump-induced free-carrier absorption ensures that the amplifier has a low-noise figure. View full abstract»

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  • Synthesis of One-Input M-Output Optical FIR Lattice Circuits

    Publication Year: 2008 , Page(s): 853 - 866
    Cited by:  Papers (4)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (723 KB) |  | HTML iconHTML  

    This paper presents a one-input M-output (1 x M)configuration and a synthesis algorithm for realizing an optical finite impulse response (FIR) lattice filter having M output channels (M ges 2). The circuit configuration has a multilayer structure consisting of multiple Mach-Zehnder interferometers with delay time differences of zero or Deltatau. It is a natural extension of the conventional two-port optical FIR lattice circuit (M = 2) . The proposed synthesis algorithm is based on factorizations of the paraunitary total transfer matrix. It realizes output responses having highest orders equal to the number of stages for all output channels. It is shown that such a synthesis algorithm maximizes the degrees of freedom for designing output responses. Two kinds of five-channel interleave filters are demonstrated as synthesized examples: one has a flat group delay response while the other has an inclined group delay response. View full abstract»

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  • [Front cover]

    Publication Year: 2008 , Page(s): 867
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    Freely Available from IEEE
  • Journal of Lightwave Technology publication information

    Publication Year: 2008 , Page(s): 868
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  • Journal of Lightwave Technology Information for authors

    Publication Year: 2008 , Page(s): 869
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  • Quality without compromise [advertisement]

    Publication Year: 2008 , Page(s): 870
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  • IEEE copyright form

    Publication Year: 2008 , Page(s): 871 - 872
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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