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Lightwave Technology, Journal of

Issue 10 • Date May15, 2010

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Displaying Results 1 - 25 of 25
  • [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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  • Table of contents

    Page(s): 1433 - 1434
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  • Detection of CH _{4} in the Mid-IR Using Difference Frequency Generation With Tunable Diode Laser Spectroscopy

    Page(s): 1435 - 1442
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (868 KB) |  | HTML iconHTML  

    This paper demonstrates detection of methane using tunable diode laser spectroscopy (TDLS) through difference frequency generation (DFG) in order to address fundamental rotational-vibrational absorption lines, located around 3404 nm. Direct detection confirms that wavelength referencing of recovered lineshapes, developed for Near infra-red (Near-IR) systems, has been successfully transferred to the presented Middle infra-red (Mid-IR) system. Traditional 1f and 2 f TDLS with WMS detection regimes are also functionally confirmed analogous to their Near-IR equivalents. View full abstract»

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  • Broadband Single-Polarization Operation in Square-Lattice Photonic Crystal Fibers

    Page(s): 1443 - 1446
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (597 KB) |  | HTML iconHTML  

    A broadband single-polarization single-mode optical fiber is proposed. One of the polarized states of the highly birefringent square-lattice photonic crystal fiber is eliminated by index-matched coupling with the modes of two cladding defects. Numerical results show that single-polarization operation with the transmission losses of one polarized state larger than 2 dB/m and the losses of another state lower than 2 dB/km can be realized in a spectral region ranged from 1477 to 1776 nm. In addition, by modifying the air holes surrounding the cladding defects, the losses of the unwanted polarized state can be enhanced to be larger than 10 dB/m, with the losses of the transmission state lower than 0.1 dB/m in a 560-nm-broad spectral region. View full abstract»

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  • A Unified FDTD Lattice Truncation Method for Dispersive Media Based on Periodic Boundary Conditions

    Page(s): 1447 - 1454
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (928 KB) |  | HTML iconHTML  

    A unified treatment for the truncation of finite-difference time-domain lattices, applicable to dispersive and conductive media alike, is proposed. The method is based on periodic boundary conditions, hence necessitating that the medium under study be periodic along the direction of truncation. When this condition (which is satisfied in many practical cases) is met, a much simpler but equally effective alternative to the PML is provided by the combination of periodic boundaries with an array-scanning method. The proposed formulation does not need any additional auxiliary variables when applied to dispersive media, unlike the PML. Applications include a Bragg filter and a negative-refractive-index super lens. View full abstract»

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  • Influence of Fabrication Error on the Characteristics of a 2-D Photonic-Crystal Cavity

    Page(s): 1455 - 1458
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (432 KB) |  | HTML iconHTML  

    Statistical studies on the scanning electron microscope (SEM) images of two-dimensional photonic crystal (PhC) slab cavities show that fabrication errors in the size and position of etched air holes follow Gaussian distribution. The influences on the characteristics of PhC cavities are then investigated and compared with those caused by fabrication error with widely-accepted uniform distribution through finite-difference time domain (FDTD) simulation. As expected, Gaussian distribution in fabrication error has more significant impact on cavity characteristics than uniform distribution simply by their difference in the fourth moment. View full abstract»

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  • Bragg Grating Inscription in GeO _2 -Doped Microstructured Optical Fibers

    Page(s): 1459 - 1467
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2119 KB) |  | HTML iconHTML  

    We present KrF excimer laser-induced dynamics of Bragg grating growths in GeO2 doped microstructured optical fibers. The studied fibers all have 6 rings of airholes in a hexagonal lattice and a GeO2 doped region in the center of the microstructure. We compare the growth rates of fiber Bragg gratings in the different microstructured fibers with UV grating inscription. The influence of the doping level, the airhole filling factor, the airhole pitch distance and the fiber orientation are investigated. We expand the range of microstructured optical fibers in which Bragg gratings can be inscribed, achieving reflection strengths that are useable for FBG-based sensing applications, even for doped regions with GeO2 concentrations as low as 1.36 mol% and 0.45 mol%. View full abstract»

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  • Distortion Correction in a High-Resolution Time-Stretch ADC Scalable to Continuous Time

    Page(s): 1468 - 1476
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1674 KB) |  | HTML iconHTML  

    Distortions caused by system components and by fundamental physical phenomena can limit the performance of photonic time-stretch ADCs. Here we use a combination of time-stretch linearization & equalization, DC-offset subtraction, and operation in a linear propagation regime to improve the signal-to-noise-and-distortion ratio by 17 dB for a 2-channel time-stretch ADC testbed and therein obtain noise-limited performance of 6-7 ENOB over a 10-GHz RF input bandwidth. Time-stretch linearization & equalization corrects for dispersion mismatches among testbed components by applying time-shifts calculated from component group delays to output ADC samples. DC-offset subtraction removes static errors due to insertion loss imbalances and Mach-Zehnder modulator bias offsets. If optical power levels are too high, nonlinear fiber propagation lowers the frequencies of dispersion-induced nulls in the RF transfer function and causes higher-order signal distortions. The 2-channel testbed can be directly scaled to a practical continuous-time system with the addition of more sub-aperture wavelength channels (total of 13 channels and 42 nm of optical bandwidth for a 90 MHz laser repetition rate). Adaptive online and fixed pre-calibrated stitching methods are demonstrated for joining data from one wavelength channel to the next. View full abstract»

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  • Analysis of Lithium Niobate Electrooptic Long-Period Waveguide Gratings

    Page(s): 1477 - 1484
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    We present an approximate step-index waveguide model for the study of lithium-niobate (LiNbO3 ) electrooptic (EO) long-period waveguide grating filters. The model takes into account the non-uniform spatial distributions of the EO coefficient and the applied electric field. Using this model, we analyze in detail the effects of the grating and waveguide parameters on the performance of the filter with the objective of identifying a set of optimal design parameters for the realization of an efficient filter. Guided by the results from the analysis, we fabricated a 12-mm-long EO grating, which produced a 24-dB rejection band at a driving voltage of 49 V. View full abstract»

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  • Dense SS-WDM Over Legacy PONs: Smooth Upgrade of Existing FTTH Networks

    Page(s): 1485 - 1495
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1157 KB) |  | HTML iconHTML  

    We propose a hybrid passive optical network (PON) architecture supporting time-division multiplexing (TDM) and dense spectrum-sliced wavelength-division multiplexing (SS-WDM) over the legacy PON infrastructure. We use a fiber Bragg grating (FBG)-based self-seeded reflective semiconductor optical amplifier (RSOA) transmitter in conjunction with a recently proposed balanced receiver (BR); identical transceiver pairs are placed at the central office and customer side. Self-seeded RSOAs obviate the need for centralized sources, providing a high power, directly modulated source. Intensity noise mitigation of this thermal source is investigated by operating the RSOA in saturation and employing the recently proposed BR. We study the optimal reflectivity for seeding that balances signal power and noise cleaning to achieve the best bit error rate (BER) possible; channel widths are comparable with dense WDM when using coherent sources. View full abstract»

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  • Enabling Technologies Incorporating Optical Tandem Single Sideband for Optical-Wireless Integrated Access Networks

    Page(s): 1496 - 1502
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (888 KB) |  | HTML iconHTML  

    In this paper, we investigate the level of crosstalk for simultaneous delivery of wired and wireless signals using optical tandem single sideband (OTSSB) transport in an optical-wireless integrated access network. Our results show that the placement of the wired data is crucial to minimize crosstalk resulting from the nonlinear optical frontend. We also propose passive interfaces for the optical-wireless integrated networks incorporating OTSSB. The performance of the interfaces is evaluated in a full-duplex experiment for simultaneous delivery of wired and wireless signals. View full abstract»

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  • Dual Waveband Remote Node for Extended Reach Full-Duplex 10 Gb/s Hybrid PONs

    Page(s): 1503 - 1509
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1260 KB) |  | HTML iconHTML  

    A remote node design for C + L band amplification is characterized and shown to cover the advanced optical power budget for a 55 km reach, 1:32 split hybrid Passive Optical Network (PON) with symmetrical full-duplex 10 Gb/s transmission. Different types of Erbium-doped fiber, designed for the C- and L-band are evaluated in a bidirectional amplification stage at the remote nodes of a ring + tree network, providing 5-10 dB of power margin for the reception of down- and upstream, despite degradation of the Optical Signal-to-Noise Ratio (OSNR). The evolution of signal power and the noise accumulation along the light path is discussed for both wavebands. View full abstract»

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  • Stationary Mode Distribution and Sidewall Roughness Effects in Overmoded Optical Waveguides

    Page(s): 1510 - 1520
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (814 KB) |  | HTML iconHTML  

    In this paper, the authors investigate analytically the transformation from the initial guided mode distribution to the stationary state and the effects of the bidimensional roughness profile, in multimode polymeric buried waveguides. In these structures, due to the geometrical dimensions and the operating wavelength, about a thousands of guided modes can propagate, even for weak core/cladding dielectric contrast. The coupling coefficients are computed by exploiting the geometrical features of the optical channels, such as the waveguide dimensions and the roughness surface statistics. The analysis gives insight on the guided/guided and guided/radiated mode interaction, and higher order solution is proposed, in the case of a great number of modes interacting over distances that are extremely long as compared to the signal wavelength and the roughness correlation length. Experimental results are valuated by means of semicontact atomic force microscopy as well as compared with existing numerical models. View full abstract»

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  • Optical Contrast Tuning in Three-Component One-Dimensional Photonic Crystals

    Page(s): 1521 - 1529
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1235 KB) |  | HTML iconHTML  

    In this study, three-component 1-D photonic crystal (PC) structures were investigated by modeling them as two-component PCs with an additional regular layer. The gap map (GM) approach and the transfer matrix method (TMM) were used in order to mathematically describe these structures. The introduction of a third component to a 1-D PC allows manipulation of the optical contrast to a high degree of precision by varying the thickness and refractive index of the additional layer. The introduction of a third component to the 1-D PC partially reduces the area of the photonic stopbands (SBs) on the GM, leaving the rest of SB area unchanged from that in the GM for the original, two-component, PC. Using this approach to decrease optical contrast in PCs, omnidirectional bands (ODBs) can be obtained in high-contrast periodic structures constructed from, for example, an array of silicon and air. Several mathematical models of three-component 1-D PCs are discussed, some of which may have practical applications. View full abstract»

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  • High-Temperature Annealing Behaviors of CO _{2} Laser Pulse-Induced Long-Period Fiber Grating in a Photonic Crystal Fiber

    Page(s): 1530 - 1535
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (699 KB) |  | HTML iconHTML  

    High-temperature annealing behaviors of long-period fiber grating (LPFG) induced by high-frequency CO2 laser pulse in an endlessly single-mode photonic crystal fiber (ESM-PCF) are investigated in this paper. We find that the change difference of effective refractive index between the air holes cladding and the solid core of the ESM-PCF both in grating fabricating and in annealing processes with different mechanisms would cause resonant wavelength red shift. Through annealing the gratings under high temperature at 600°C-650°C, its stability, linearity, and repeatability to temperature and tensile strain responses under high temperature condition can be greatly enhanced. Our study shows that the changes in fiber glass structure would have significant influence on the optical properties of ESM-PCF LPFG and thus will help understanding of the forming mechanisms and physical characteristics of ESM-PCF LPFG. In addition, ESM-PCF LPFGs can be used as temperature or strain sensors after annealing at high temperature of 600°C-650°C. View full abstract»

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  • Adaptive Receiver Structures for Fiber Communication Systems Employing Polarization Division Multiplexing: High Symbol Rate Case

    Page(s): 1536 - 1546
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1125 KB) |  | HTML iconHTML  

    Polarization division multiplexing (PDM) has been proposed as a scheme for increasing data rates in fiber optic communication systems. In the PDM scheme, the use of two orthogonal polarizations as alternative data paths is a promising approach in terms of doubling the information rate relative to conventional schemes. However, due to the severe distortion caused by the propagation medium, especially the Polarization mode dispersion (PMD), the development of receiver compensation methods are critical for the deployment of PDM based transceivers. This article proposes a receiver compensation method for high symbol rate fiber optic communication links, where the two data streams sent through orthogonal polarizations are mixed by the fiber channel not only in space but also in time. The proposed receiver algorithm adaptively recovers the original pair of data streams from their space-time mixtures. We also provide simulation results for an end-to-end fiber communication link to illustrate the performance of the proposed approach. View full abstract»

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  • Bandwidth Improvement in Multimode Optical Fibers Via Scattering From Core Inclusions

    Page(s): 1547 - 1555
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1710 KB) |  | HTML iconHTML  

    We show that a controlled intentional mode coupling induced via scattering from core inclusions can substantially improve the bandwidth of graded index multimode fibers with centerline defect. We present a comprehensive analysis of the impact of the dielectric constant, size, density, and location of micrometer size inclusions on the bandwidth and attenuation of these fibers. We show that using a proper design, the bandwidth of a 1-km-long fiber can improve from 693-MHz to more than 2.5-GHz with less than 1-dB additional power loss. We also show that in practice, it is possible to obtain the desired level of mode coupling by exposing the photosensitive core of the fiber to a UV laser, therefore creating the micrometer size inclusions after the draw process. View full abstract»

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  • Loss Analysis of High Order Modes in Photonic Crystal Vertical-Cavity Surface-Emitting Lasers

    Page(s): 1556 - 1563
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1693 KB) |  | HTML iconHTML  

    A new technique for analyzing the loss of high order modes in photonic crystal VCSEL is reported. The technique proposed is a semi-empirical approach that uses comparison to experimental data. For that purpose, photonic crystal VCSEL devices of single mode and multi mode are fabricated and measured for device characteristics comparison. The fabricated devices are modeled using finite difference frequency domain technique for the purpose of investigating the photonic crystal guided modes and loss analysis. In order to verify the findings, full three dimensional analyses are performed based on the fabricated single mode and multi mode devices structures using common finite difference time domain technique. The results show close agreement between the computed and experiment findings, justifying the used of the proposed semi-empirical technique for analyzing the loss of high order modes in photonic crystal VCSEL. Results for guided modes and near- and far-field are also presented for the photonic crystal VCSEL. View full abstract»

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  • Joint Statistics and MLSD in Filtered Incoherent High-Speed Fiber-Optic Communications

    Page(s): 1564 - 1572
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (936 KB) |  | HTML iconHTML  

    In this paper, signal statistics and their utilization for detection in narrowly filtered equalized high-speed fiber-optic communications are investigated experimentally. Tradeoffs between log-likelihood metric applications and oversampling are covered in detail. It is, for the first time, demonstrated that performance loss in bandwidth-limited systems can be nearly fully recovered (to within 0.5 dB) by taking advantage of bandwidth-limitation-induced noise correlations and oversampling. View full abstract»

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  • MLSE-Based DQPSK Transmission in 43 ~ Gb/s DWDM Long-Haul Dispersion-Managed Optical Systems

    Page(s): 1573 - 1581
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1408 KB) |  | HTML iconHTML  

    We analyze by simulation the performance of the differential quadrature phase-shift keying (DQPSK) modulation format in dispersion-managed multi-span WDM optical systems at 43 Gb/s, with 50 GHz channel spacing, in the presence of fiber nonlinearity. We show that the use of maximum-likelihood sequence-estimation (MLSE) receivers significantly helps to increase tolerance to dispersion map design. We also show that the use of an MLSE algorithm which takes into account the correlation of samples allows to improve system performance, partially mitigating the impact of fiber non-linearity. Some of the results presented here hint at a possible use of similar techniques in the context of coherent systems as well. View full abstract»

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  • OFS-21

    Page(s): 1582
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    Freely Available from IEEE
  • Calls for papers on semiconductor lasers

    Page(s): 1583
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    Freely Available from IEEE
  • Announcing an issue of the IEEE JSTQE on NonlinearOptical Signal Processing

    Page(s): 1584
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    Freely Available from IEEE
  • Journal of Lightwave Technology Information for authors

    Page(s): C3
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    Freely Available from IEEE

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