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Lightwave Technology, Journal of

Issue 13 • Date July1, 2010

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Displaying Results 1 - 22 of 22
  • [Front cover]

    Page(s): C1
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  • Journal of Lightwave Technology publication information

    Page(s): C2
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  • Table of contents

    Page(s): 1871 - 1872
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  • First-Order PMD Outage Prediction Based on Outage Maps

    Page(s): 1873 - 1881
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (871 KB) |  | HTML iconHTML  

    We compare the applicability of different methods for the calculation of first order polarization-mode dispersion (PMD) outage probabilities under the Maxwellian probability density assumption for the differential group delay. Results based on measured outage maps are contrasted with outage predictions using various simplifying approximations. We present a comprehensive data set of measured PMD outage maps at 10.7 Gb/s using non return-to-zero and return-to-zero on-off keying in combination with both standard threshold detection and maximum likelihood sequence estimation, with and without residual chromatic dispersion. View full abstract»

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  • Influence of Surface Tension and Inner Pressure on the Process of Fibre Drawing

    Page(s): 1882 - 1888
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (534 KB) |  | HTML iconHTML  

    The present contribution deals with thermofluidynamical features occurring during the drawing of capillaries for microstructured optical fibres. Here, the process stability depends strongly on flow and thermal processes taking place as a preform is heated and drawn in the furnace. This is the case particularly for hollow fibres for which the existence of the inner hole directly depends on material parameters such as the surface tension and the rheological properties and on process parameter such as hole internal pressure and the process temperature. A fluid-mechanics model suggested in the literature that makes use of asymptotic analysis based on small aspect ratio of the micro capillaries, has been revisited and improved recently and the leading-order equations have been then examined in some asymptotic limits by Luzi et al. Starting from the novel class of solutions of the simplified equations of motion the present paper focuses on the effect of both surface tension and internal hole pressure since those are of essential importance during drawing. Thus, comparisons with experimental data are performed, in order to validate the analytical model developed in, which will be briefly presented here. The theoretical model gives very accurate predictions both when the internal hole is pressurized or when no pressure is applied, as long as the temperature does not reach too high values. View full abstract»

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  • High-Speed Optical Label Recognition Technique Using an Optical Digital-to-Analog Conversion and Its Application to Optical Label Switch

    Page(s): 1889 - 1896
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1484 KB) |  | HTML iconHTML  

    Operation performance of a 40 Gbps, 2-bit Optical Digital-to-Analog converter (ODAC) and its application to optical label switching systems have been investigated. The device is composed of a 1 × 2 multi-mode interference (MMI) splitter, one-bit-delay line, and a 2 × 1 MMI combiner. It has a high-mesa structure fabricated on InP-based materials. Dependence of output signal level on input signal wavelength and device temperature was measured. Due to the optical phase variation caused by the refractive index change with wavelength and temperature, output signal level varied, and it agreed well with simulation results. Four-level signals were generated and a quarter dependence of phase on temperature and wavelength compared with that for 10-Gbit/s was verified. Next, operation tolerance of the ODAC as an optical label processor, bit error rate (BER) of the digital-to-analog (DA)-converted signal was simulated. The tolerance against fluctuation of light source power, optical phase in the device, optical chirp, and extinction ratio of input signal was estimated. For all parameters, operation tolerance could be kept, but that for 40 Gbps is smaller than that for 10 Gbps. Then, autonomous label processing and optical label switching performance using a gate pulse generation scheme based on phase-shifted preamble was investigated. Optical DA conversion and three kinds of optical label were recognized at a bit rate of 40 Gbps, and optical packet transfer could be confirmed. View full abstract»

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  • Multidimensional Dynamic Displacement and Strain Measurement Using an Intensity Demodulation-Based Fiber Bragg Grating Sensing System

    Page(s): 1897 - 1905
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1338 KB) |  | HTML iconHTML  

    We set up a multidimensional dynamic fiber Bragg grating (FBG) displacement and strain sensing system. The proposed sensing system allows the FBGs to have the ability to measure transient point-wise displacement (in-plane and out-of-plane) and strain responses simultaneously with high sensitivity. The sensing system employs a long-period fiber grating filter and two FBG filters to dynamically demodulate the responses of the FBG sensors. To demonstrate the dynamic sensing ability and the application of the proposed system, the transient elastic wave propagation in a solid subjected to vertical and lateral impact loadings are investigated. A laser Doppler vibrometer is employed in our experiments simultaneously to verify the transient responses of out-of-plane particle transient motions measured by the out-of-plane FBG displacement sensor. The in-plane displacement measurement ability is demonstrated by the responses obtained by two geometrically orthogonal in-plane FBG displacement sensors. Dynamic strain sensing ability of our all-fiber sensing system is also demonstrated. The experimental results both in time domain and frequency domain show that the proposed FBG sensing system is capable of performing real-time displacement (out-of-plane and in-plane) and strain measurements. View full abstract»

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  • Differential Gain of Closely Spaced Energy States in Quantum Dashes

    Page(s): 1906 - 1912
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (563 KB) |  | HTML iconHTML  

    Simple quasi-equilibrium model for quantum dash (QDash) active material is derived for closely spaced energy states. The model is used to study the differential gain of Qdash for different key parameters. Expressions for the electron and the hole occupation probabilities as a function of electron concentration are derived. The derived analytical model shows excellent agreement with numerical simulation. The differential gain of Qdash active layer is calculated for different doping concentration and different electron energy separation between adjacent states. We find that when the electron energy states are widely separated, the differential gain can be slightly enhanced at low-energy detuning by doping the dashes by p-type doing. On the other hand, our calculations reveal that when the electron energy states are close to each other, doping the dashes by either n-type or p-type concentration will not enhance the differential gain. View full abstract»

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  • Lithium Niobate Ridge Waveguides Fabricated by Ion Implantation Followed by Ion Beam Etching

    Page(s): 1913 - 1916
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (299 KB) |  | HTML iconHTML  

    A new fabrication method for lithium niobate ridge waveguides is reported. Lithium niobate ridge waveguide with a smooth surface was fabricated by O+ ions implanted combined with Ar ion beam etching. The beam propagation method (BPM) was used to simulate the properties of planar and ridge waveguides by use of a reconstructed refractive index profile. The simulation results match to the experimental results very well, and the loss value of the ridge waveguide is about 2 dB/cm. View full abstract»

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  • A Radio-Over-GI-POF Transport System

    Page(s): 1917 - 1921
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (590 KB) |  | HTML iconHTML  

    A novel radio-over-graded index-plastic optical fiber (GI-POF) transport system is proposed based on vertical-cavity surface-emitting lasers (VCSELs) and light injection-locking technique. Comparing with other light sources, VCSEL provide a good balance between its cost and quality for intrabuilding network applications. To further enhance its transmission performance, we are the first one to integrate VCSELs with light injection-locking technique in radio-over-GI POF intrabuilding network. Impressive upgrading of third-order intermodulation distortion to carrier ratio, spurious-free dynamic range, error vector magnitude, and bit error rate were experimentally obtained and discussed in the paper. View full abstract»

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  • Efficient Scheduling and Grant Sizing Methods for WDM PONs

    Page(s): 1922 - 1931
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (530 KB) |  | HTML iconHTML  

    Bandwidth allocation and transmission grant scheduling are problems of particular interest to multichannel passive optical networks (PONs). While prior studies have addressed each of these subproblems separately, to the best of our knowledge, a study on the joint problem has been lacking. In this paper, we first revisit the sequential model and derive a more efficient Integer Linear Program (ILP) for the nonjoint problem that yields up to nearly 12% reduction in makespan and 11% increase in average channel utilization. Then, we investigate the joint problem of bandwidth allocation and transmission grant scheduling in multichannel optical access networks using a scheduling theoretic approach. We derive two ILP models and compare them with the sequential model. Results show that joint scheduling and sizing algorithm achieves significant improvement in terms of scheduling cycle length when compared to the nonjoint models. Since the models for the joint problem was shown to be very hard to solve, except for small-sized networks, we introduce a Tabu search heuristic that provides near-optimal solutions in significantly shorter times. We further perform a packet-level simulation to study the benefit of our new methods. View full abstract»

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  • Efficient Extraction of Input Pump Powers From Pump Power Integrals in the Design of Raman Fiber Amplifiers

    Page(s): 1932 - 1937
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    A novel method of extracting input pump powers from pump power integrals with high efficiency is proposed for the first time. In this method, a set of coupled nonlinear equations of input pump powers for given target pump power integrals are constructed. Finding the input pump powers corresponding to the target pump power integrals becomes finding solution of this set of nonlinear equations. A modified Newton's root-finding method is adopted to solve the nonlinear equations. To verify the proposed method, the input pump powers of a broadband (10 THz) Raman fiber amplifier that contains 100 signal channels and is counter pumped by 4 pumps is searched for given target pump power integrals. It is demonstrated that 3 iterations are enough for the method to achieve a satisfactory convergence. Compared with the previously reported techniques where hundreds of iterations are usually involved, the proposed method reduces the computational effort by two orders of magnitude. View full abstract»

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  • Submicron Etched Beam Splitters Based on Total Internal Reflection in GaAs–AlGaAs Waveguides

    Page(s): 1938 - 1943
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (434 KB) |  | HTML iconHTML  

    Submicron etched beam splitters are designed, fabricated and characterized in Al0.9Ga0.1As-GaAs waveguides. Beam splitter transmission and reflection characteristics show clear dependence on gap dimension and angle of incidence. It is possible to obtain 8 to 30% power transmission by adjusting the gap dimension and angle of incidence. The experimental results agree well with three-dimensional (3-D) finite difference time domain (FDTD) simulations. The effect of imperfections, mainly the slope of etched sidewalls and variations in etch depth are investigated using 3-D FDTD. Design guidelines for low loss etched beam splitters are also given. View full abstract»

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  • Loss Differentiation in OBS Networks With Limited or No Wavelength Conversion

    Page(s): 1944 - 1957
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (710 KB) |  | HTML iconHTML  

    Quality of Service differentiation is an open research issue in optical burst switching (OBS) networks. Most proposals assume full wavelength-conversion, but wavelength converters are still very complex and expensive, and accordingly limited and no wavelength conversion OBS networks are likely to be the most common scenarios. In this paper, we define and analyze the QoS Multiple Wavelength Simultaneous Transmission technique (QoS-MWST), a novel method for providing loss differentiation in OBS networks with limited or no wavelength-conversion capability. In QoS-MWST, multiple copies of each burst are simultaneously sent on different wavelengths, so as to increase the chances of data delivery, and loss differentiation is achieved by properly sending more copies of the higher-priority bursts. Through analysis and extensive simulation experiments, we demonstrate that QoS-MWST can provide loss differentiation in OBS networks without full wavelength-conversion capability more efficiently than other differentiation techniques proposed in the literature. View full abstract»

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  • Outage Statistics in a Waveplate Hinge Model of Polarization-Mode Dispersion

    Page(s): 1958 - 1968
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1095 KB) |  | HTML iconHTML  

    The properties of the waveplate hinge model of polarization-mode dispersion (PMD) are studied in detail, and its statistics are compared to those of the traditional hinge model based on the assumption of an isotropic output after each hinge. In particular, the probability density function of the differential group delay for each individual frequency band is computed using a combination of importance sampling and the cross-entropy method. The outage probability is then obtained combining these results with the outage map method, allowing the fraction of bands with unacceptable outage probabilities to be quantified by the noncompliant capacity ratio (NCR). The results show that the traditional hinge model significantly overestimates the NCR compared to the waveplate hinge model. View full abstract»

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  • Load-Balanced Optical Switch for High-Speed Router Design

    Page(s): 1969 - 1977
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    A hybrid electro-optic router is attractive, where packet buffering and table lookup are carried out in electrical domain and switching is done optically. In this paper, we propose a load-balanced optical switch (LBOS) fabric for a hybrid router. LBOS comprises N linecards connected by an N-wavelength WDM fiber ring. Each linecard i is configured to receive on channel λi. To send a packet, it can select and transmit on an idle channel based on where the packet goes. The packet remains in the optical domain all the way from input linecard to output linecard. Meanwhile, the loading in the ring network is perfectly balanced by spreading the packets for different destinations to use different wavelengths, and the packets for the same destination to use different time slots. With the pipelined operation of the LBOS, we show that LBOS can yield close-to-100% throughput performance. To address the ring-fairness problem under the inadmissible traffic patterns, an efficient throughput-fair scheduler is devised. To efficiently support multicast traffic, a simple multicast scheduler is also proposed. Finally, the linecard placement problem is investigated for further cutting down the average packet delay. View full abstract»

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  • Chaos Synchronization and Communication in Mutually Coupled Semiconductor Lasers Driven by a Third Laser

    Page(s): 1978 - 1986
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (765 KB) |  | HTML iconHTML  

    We numerically investigate the chaos synchronization and message transmission between two mutual coupling semiconductor lasers (MCSLs) subject to identical unidirectional injections (UIs) from an external cavity semiconductor laser (ECSL). The synchronization between the MCSLs is realized through injection locking in conjunction with symmetric operation. The simulation results show that stable isochronal synchronization between the MCSLs can be achieved under proper driving injections. This type of synchronization is robust to parameter mismatch up to tens of percentage and frequency detuning of several tens of gigahertz, which is much better than those of the MCSLs systems with self-feedback. Moreover, the investigations on the mutual chaos pass filtering effects and the message transmission indicate that the isochronal synchronization allows mutual message exchange with a bit rate higher than 10 Gb/s, when the chaos modulation technology is adopted. In addition, the MCSLs can synchronize with the ECSL for proper UI and MC, which provides an opportunity for array chaos synchronization and chaos communication networks. Finally, leader/laggard synchronization can also be achieved in the proposed system. View full abstract»

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  • Photonic Down-Conversion of Millimeter Wave Multiband Orthogonal Frequency Division Multiplexing Ultra-Wideband Using Four Wave Mixing in an Electro-Absorption Modulator

    Page(s): 1987 - 1993
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (604 KB) |  | HTML iconHTML  

    We propose and demonstrate a novel and cost-effective photonic down-conversion scheme for millimeter wave (mm-wave) over fiber (MoF) uplinks using an electro-absorption modulator (EAM) at a base station. Two wavelengths with frequency difference of flo, used as dual wavelength, are incident to an EAM that is driven by an mm-wave signal at fmm to obtain optical subcarrier modulation. Due to four-wave mixing (FWM), two new wavelengths are generated inside the EAM and used for the optical carriers for the uplink. One of the generated two wavelengths and one of two mm-wave signal subcarriers is separated by fmm-flo in frequency, thus down-converted. Furthermore, down-conversion with tunability of optical carrier to optical subcarrier power ratio can be achieved by simply controlling the dual wavelength power into the EAM. We experimentally investigate the efficiency of the FWM versus EAM reverse bias voltage and input optical power. The performance of the proposed scheme for down-conversion of a 30 GHz multiband (MB) orthogonal frequency division multiplexing (OFDM) ultra-wideband (UWB) is also investigated in terms of error vector magnitude (EVM) versus RF and LO modulation index, and received optical power at the photodetector. View full abstract»

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  • Estimating the Performance of Direct-Detection DPSK in Optical Networking Environments Using Eigenfunction Expansion Techniques

    Page(s): 1994 - 2003
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    In-band crosstalk, due to multiple interferers, has been identified as one of the most severe impairments in optical transparent networks, especially in the ones with a large number of nodes and a high wavelength density. Due to its robustness to in-band crosstalk differential phase-shift keying (DPSK) emerges as an attractive modulation scheme to be used in such environments. This paper proposes a rigorous formulation to estimate the performance of direct-detection DPSK receivers using an eigenfunction expansion technique in the time domain. The method takes into account both the in-band crosstalk, due to an arbitrary number of interfering terms, and the amplified spontaneous emission noise and is able to deal with any combination of optical and electrical filter shapes. Using this method the accuracy of an approximation based on the wideband optical filtering assumption was evaluated and shown that the approximation, although not providing reliable results for the error probabilities, can be used with confidence to compute power penalties due to in-band crosstalk. Furthermore, the crosstalk tolerance of DPSK over on-off keying was quantified and shown that this tolerance is reduced when the number of interferers increases. View full abstract»

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  • Multi-Granular Waveband Assignment and Protection in WDM Networks

    Page(s): 2004 - 2013
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (316 KB) |  | HTML iconHTML  

    Waveband switching (WBS) is introduced to group multiple wavelengths together as a band or fiber and switch the group using a single port whenever possible. Instead of using the traditional optical cross-connects (T-OXCs), WBS networks employ multi-granular optical cross-connects (MG-OXCs) to switch the traffic at different granularities. In this work, we first briefly review and discuss the development in MG-OXC architecture design, routing and wavelength assignment algorithms, and protection schemes in WBS networks. Then two new schemes are proposed to solve the waveband assignment problem and waveband protection problem. In the first scheme, we demonstrate that factors such as bypass traffic and node degree can affect the waveband switching efficiency. A new hierarchical waveband assignment (HWA) algorithm is then proposed to effectively take these wavebanding factors into consideration for saving ports. In the second scheme, we introduce the concept of band-segment and explore band-segment based protection schemes to achieve the goal of port reduction, the sharing of resources and survivability in WBS networks. Our simulations show that the proposed HWA scheme outperforms a representative approach, namely balanced path routing with heavy-traffic first waveband assignment (BPHT), by up to 18% in terms of port reduction. For the first time, our study demonstrates that protection and the sharing of resources can be achieved without sacrificing port saving when the proposed concept of band-segment is efficiently adopted in WBS networks. View full abstract»

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  • 21st International conference on optical fiber sensors

    Page(s): 2465 - 2466
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    Freely Available from IEEE
  • Journal of Lightwave Technology Information for authors

    Page(s): C3
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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.

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Meet Our Editors

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