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Lightwave Technology, Journal of

Issue 22 • Date Nov.15, 2010

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Displaying Results 1 - 25 of 31
  • [Front cover]

    Publication Year: 2010 , Page(s): C1
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  • Journal of Lightwave Technology publication information

    Publication Year: 2010 , Page(s): C2
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  • Table of contents

    Publication Year: 2010 , Page(s): 3187 - 3188
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  • Light Emission Enhancement of GaN-Based Photonic Crystal With Ultraviolet AlN/AlGaN Distributed Bragg Reflector

    Publication Year: 2010 , Page(s): 3189 - 3192
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (618 KB) |  | HTML iconHTML  

    In this study, we demonstrated two-dimensional (2-D) photonic crystal band-edge coupling operation in the ultraviolet wavelength range. The light extraction enhancement was obtained from the photonic crystal structure with an ultraviolet AlN/AlGaN distributed Bragg reflector (UVDBR). The DBR provides a high reflectivity of 85% with 15-nm stopband width. A fivefold enhancement in photoluminescence emission was also achieved compared with the emission from the unpatterned area on the same sample at 374 nm wavelength. We also study the photonic crystal bandedge coupling with finite-difference time-domain and plane-wave expansion methods. View full abstract»

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  • Selective-Fluid-Filling Technique of Microstructured Optical Fibers

    Publication Year: 2010 , Page(s): 3193 - 3196
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (271 KB) |  | HTML iconHTML  

    A versatile technique is demonstrated to fill selectively a fluid into desired air holes in a microstructured optical fibers (MOFs). A fan-shaped groove is carved on the fiber surface to expose selected air holes to atmosphere by a micromachining system consisting of a femtosecond IR laser and a microscope. Then a fluid is filled into the exposed air holes through the carved groove with the well-known capillarity action. Such a technique can be used to fill selectively several different types of fluid samples into desired air holes in an MOF by means of carving fan-shaped grooves on different orientations of the fiber surface. View full abstract»

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  • Analysis and Design of Bragg Fibers Using a Novel Confinement Loss Diagram Approach

    Publication Year: 2010 , Page(s): 3197 - 3206
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (708 KB) |  | HTML iconHTML  

    In this paper, a confinement loss diagram (CLD) is proposed as a novel design tool for Bragg fibers. The CLD is a 2-D pseudocolor diagram, which presents the loss properties of a Bragg fiber in a coordinate of normalized frequency and the effective refractive index (ωr, neff), to quantitatively characterize the Bragg cladding without the parameters of the core. The CLD is derived from a ray reflection model, which describes the propagation in Bragg fibers as reflection and ray trajectory. Confinement loss is first determined from the reflection process and then developed into a 2-D CLD. In this paper, the confinement loss calculation with the ray reflection model is first shown to be accurate for Bragg fibers with a core radius as small as 0.8 wavelength, both in the TE modes and the TM modes. Then, the CLD is exploited to characterize the level core Bragg fiber and the depressed core Bragg fiber. It is found that the level core fiber is suitable for wide band designs, while the depressed core fiber is good for narrow band designs. Lastly, the CLD is applied to characterize the loss properties of different order bandgaps, so that the propagation region can be located for optimum Bragg fiber design. View full abstract»

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  • Design of Photonic Crystal Semiconductor Optical Amplifier With Polarization Independence

    Publication Year: 2010 , Page(s): 3207 - 3211
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (558 KB) |  | HTML iconHTML  

    Slow-light effects in photonic crystal (PC) waveguides can enhance light-mater interaction near the photonic band edge, which can be used to design a short cavity length semiconductor optical amplifier (SOA). In this paper, a novel SOA based on slow-light effects in PC waveguides (PCSOA) is presented. To realize the amplification of the optical signal with polarization independence, a PCSOA is designed with a compensated structure. The cascaded structure leads to a balanced amplification to the TE and TM polarized light. View full abstract»

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  • Experimental Comparison of Fundamental Mode Content in Er:Yb-Codoped LMA Fibers With Multifilament- and Pedestal-Design Cores

    Publication Year: 2010 , Page(s): 3212 - 3219
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (976 KB) |  | HTML iconHTML  

    We report on fundamental mode content measurements performed on single-frequency large mode area fiber amplifiers based on Er:Yb-codoped multifilament-core (MFC) and step-index pedestal-design fibers. The mode content of the amplifier output was analyzed with respect to free-space TEM modes using a nonconfocal scanning ring cavity. At power levels of several watts, the commercial step-index pedestal-design fibers with respective core diameters of 23 and 25 m showed a mode content exceeding 80%. However, a mode content of up to 95% could be obtained with an MFC fiber also with larger core diameter of 31/28 m in hexagonal shape. To the best of our knowledge, we utilized the nonconfocal scanning ring cavity technique for the first time in the wavelength region of 1.5 m and additionally for the first time on fibers with pedestal as well as MFC design. View full abstract»

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  • An Experimental Study of XPM and SPM Upon a Long-Haul RZ-DSPK Transmission System With a Block-Type Dispersion Map

    Publication Year: 2010 , Page(s): 3220 - 3225
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (283 KB) |  | HTML iconHTML  

    We report on an experimental study that focus on the cross phase modulation (XPM) and self-phase modulation (SPM) effects upon the transmission performance of 10 Gb/s-based long-haul return-to-zero differential phase-shift keying system, using the block-type dispersion map. Experimental results show that for the channel at the system zero dispersion wavelength SPM causes a larger degradation as compared to channels at other wavelengths. Whereas it was observed that the XPM impairment does not vary significantly for channels at or away from the system zero dispersion wavelength. View full abstract»

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  • The Impact of Inhomogeneities in the Phosphor Distribution on the Device Performance of Phosphor-Converted High-Power White LED Light Sources

    Publication Year: 2010 , Page(s): 3226 - 3232
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (863 KB) |  | HTML iconHTML  

    We present a study by optical ray-tracing in order to determine the impact of an inhomogeneous phosphor distribution in the color conversion elements (CCE) of phosphor-conversion- based white LED light sources. It turns out that in particular the color temperature and its angular variation, but also the flux-output are highly sensitive towards phosphor distribution variations. View full abstract»

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  • Towards a Realistic Modelling of Ultra-Compact Racetrack Resonators

    Publication Year: 2010 , Page(s): 3233 - 3242
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (848 KB) |  | HTML iconHTML  

    We discuss all the necessary parameters to describe optical racetrack micro resonators fabricated with silicon on insulator (SOI) technology. We focus on some fundamental aspects crucial for a comprehensive and realistic modelling of racetrack resonators as building blocks of complex add-drop filters, like SCISSOR (Side-Coupled Integrated Spaced-Sequences of Resonators) or CROW (Coupled Resonator Optical Waveguides). When the radius of curvature is lower than 5 μm, and/or the separation gaps between waveguide and resonator is small, dispersion law, effective index mismatch, and mode mismatch between bend and straight waveguides are relevant for modelling. A new mode solver, specifically suited for high index contrast small mode area waveguides, is used whose results are compared with the measurement of the optical response of some resonant devices. View full abstract»

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  • Distributed Vibration Sensor Based on Coherent Detection of Phase-OTDR

    Publication Year: 2010 , Page(s): 3243 - 3249
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (813 KB) |  | HTML iconHTML  

    We developed a distributed vibration sensor by using heterodyne detection and signal processing of moving averaging and moving differential for the phase optical time domain reflectometry system. The broadband acoustic frequency components generated by pencil-break vibration have been measured and identified in location by our distributed vibration sensor for the first time. Pencil break measurement is a standard technique to emulate the acoustic emission of cracks in concrete or steel bridges for early crack identification. The spatial resolution is 5m and the highest frequency response is 1 kHz, which is limited by the trigger frequency of data acquisition card. This new sensing system can be used for vibration detection of health monitoring of various civil structures as well as any dynamic monitoring requirement. View full abstract»

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  • Design and Analysis of Single-Mode Polymer Segment Cladding Optical Fibers

    Publication Year: 2010 , Page(s): 3250 - 3257
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (976 KB) |  | HTML iconHTML  

    The mode properties of polymer segment cladding optical fibers are investigated. Numerical results demonstrate that for the previous reported fiber configurations, the LP11 mode is generally not the lowest loss high-order mode. As a result, the fibers are not single-mode guided. Improved design is presented to eliminate all the high-order modes of the fibers. In addition, a modified segment cladding optical fiber is proposed. The segment profile of the fiber is modified to effectively eliminate the high-order modes and confine the fundamental mode more effectively simultaneously. Numerical investigations demonstrate that single-mode operation with low confinement and bending loss can be achieved in the proposed fiber. View full abstract»

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  • An Ameliorated Phase Generated Carrier Demodulation Algorithm With Low Harmonic Distortion and High Stability

    Publication Year: 2010 , Page(s): 3258 - 3265
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (801 KB) |  | HTML iconHTML  

    A novel ameliorated phase generated carrier (PGC) demodulation algorithm based on arctangent function and differential-self-multiplying (DSM) is proposed in this paper. The harmonic distortion due to nonlinearity and the stability with light intensity disturbance (LID) are investigated both theoretically and experimentally. The nonlinearity of the PGC demodulation algorithm has been analyzed and an analytical expression of the total-harmonic-distortion (THD) has been derived. Experimental results have confirmed the low harmonic distortion of the ameliorated PGC algorithm as expected by the theoretical analysis. Compared with the traditional PGC-arctan and PGC-DCM algorithm, the ameliorated PGC algorithm has a much lower THD as well as a better signal-to-noise-and-distortion (SINAD). A THD of below 0.1% and a SINAD of 60 dB have been achieved with PGC modulation depth (C value) ranges from 1.5 to 3.5 rad. The stability performance with LID has also been studied. The ameliorated PGC algorithm has a much higher stability than the PGC-DCM algorithm. It can keep stable operations with LID depth as large as 26.5 dB and LID frequency as high as 1 kHz. The system employing the ameliorated PGC demodulation algorithm has a minimum detectable phase shift of 5 μrad/√Hz @ 1 kHz, a large dynamic range of 120 dB @ 100 Hz, and a high linearity of better than 99.99%. View full abstract»

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  • Cavity Enhanced Internal Photoemission Effect in Silicon Photodiode for Sub-Bandgap Detection

    Publication Year: 2010 , Page(s): 3266 - 3272
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (985 KB) |  | HTML iconHTML  

    In this paper, a new approach for the near infrared sub-bandgap detection in Si-based devices is investigated. In particular, the design, the realization and the characterization of a back illuminated silicon resonant cavity enhanced Schottky photodetectors, working at 1.55 μm, are reported. The photodetectors are constituted by Fabry-Perot microcavity incorporating a Schottky diode. The working principle is based on the internal photoemission effect enhanced by cavity effect. Performances devices in terms of responsivity, free spectral range, finesse and estimated bandwidth are reported. View full abstract»

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  • Design of Ge–SiGe Quantum-Confined Stark Effect Electroabsorption Heterostructures for CMOS Compatible Photonics

    Publication Year: 2010 , Page(s): 3273 - 3281
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (856 KB) |  | HTML iconHTML  

    We describe a combined 6 × 6 k · p and one-band effective mass modelling tool to calculate absorption spectra in Ge-SiGe multiple quantum well (MQW) heterostructures. We find good agreement with experimentally measured absorption spectra of Ge-SiGe MQW structures described previously in the literature, proving its predictive capability, and the simulation tool is used for the analysis and design of electroabsorption modulators. We employ strain-engineering in Ge-SiGe MQW systems to design structures for modulation at 1310 nm and 1550 nm. View full abstract»

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  • Design of Polarization De-Multiplexer and PMD Compensator for 112 Gb/s Direct-Detect PDM RZ-DQPSK Systems

    Publication Year: 2010 , Page(s): 3282 - 3293
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (938 KB) |  | HTML iconHTML  

    The design of a polarization de-multiplexer and a polarization mode dispersion compensator (PMDC) for direct-detect polarization division multiplexed (PDM) return-to-zero differential quadrature phase shift keying (RZ-DQPSK) systems are studied in detail. The impact of polarization dependent loss is studied in polarization de-multiplexers with different error detection configurations for both bit-aligned and bit-interleaved PDM systems. The level of the clock frequency of the combined pulse train of the two polarizations is proposed as the error signal for the PMDC. It enables the PMDC to work in the cancellation mode. Two separate control loops are proposed for the polarization de-multiplexer and the PMDC to allow them to work independently. The DGD tolerances for the one-stage and two-stage PMDC are measured and discussed. Finally the glitch problem in the polarization tuning algorithm is studied. An advanced dithering algorithm and the corresponding architecture of the polarization controller are proposed to solve the glitch problem. View full abstract»

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  • Phase-Shifted White-Light Interferometry for the Absolute Measurement of Fiber Optic Mach–Zehnder Interferometers

    Publication Year: 2010 , Page(s): 3294 - 3299
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (312 KB) |  | HTML iconHTML  

    An all-fiber 3 times; 3 coupler based phase-shifted white-light interferometry is presented, with which the absolute optical path difference (OPD) of a Mach-Zehnder interferometer can be measured automatically. The continuous test shows that the variation is ±0.5 μm when measuring a beam length of ~10 m with an OPD of 1847 μm. The technique is successfully demonstrated to measure static measurands, including strain, temperature and weight. View full abstract»

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  • Operation of Brillouin Optical Correlation-Domain Reflectometry: Theoretical Analysis and Experimental Validation

    Publication Year: 2010 , Page(s): 3300 - 3306
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (445 KB) |  | HTML iconHTML  

    We theoretically and experimentally analyze the operation of Brillouin optical correlation-domain reflectometry (BOCDR). First, we experimentally confirm that BOCDR is not based on stimulated Brillouin scattering but on spontaneous Brillouin scattering. Then, we theoretically prove that the spatial resolution of BOCDR is given well by the same expression as that of Brillouin optical correlation-domain analysis (BOCDA). Finally, we demonstrate that the modulation amplitude of the laser frequency, which has been conventionally limited to a half of the Brillouin frequency shift, can be enhanced further by employing a sensing fiber shorter than a half of the measurement range. View full abstract»

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  • Accounting for PMD Temporal Correlation During Lightpath Set Up in Transparent Optical Networks

    Publication Year: 2010 , Page(s): 3307 - 3313
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (246 KB) |  | HTML iconHTML  

    In transparent optical networks, the signal transmission is degraded by optical layer physical impairments. Therefore, lightpaths may be blocked due to unacceptable quality of transmission (QoT). Among physical impairments, polarization mode dispersion (PMD) is a detrimental effect which has stochastic characteristics. Moreover, PMD depends on time-variant factors, such as the temperature and the fiber stress. View full abstract»

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  • A Simple Method of Jitter Evaluation for Designing Phase-Locked Loops for Optical Communication Systems

    Publication Year: 2010 , Page(s): 3314 - 3322
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (338 KB) |  | HTML iconHTML  

    A simple method for evaluating jitter generation is proposed for phase-locked loops (PLLs) applied to optical communication systems. The precise but complex expressions in the conventional method involving the phase noise of the voltage-controlled oscillator, the jitter-transfer function of the PLL, and integration using a filter function are greatly simplified with the objective of providing a simple estimate of the jitter generation avoiding iterative design procedures. These simplifications together with the data from the International Telecommunication Union (ITU)-T Recommendations lead to an integral-free expression with only a small number of parameters, which enables jitter evaluation using a hand-held calculator. By applying bandwidth limits to the jitter tolerance and transfer specifications, both the sufficient and insufficient conditions for the phase noise of a voltage-controlled oscillator are obtained to enable the efficient design of a PLL with the jitter generation specified in the ITU-T Recommendations. View full abstract»

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  • Influence of Acoustic Perturbation of Fibers in Phase-Noise-Compensated Optical-Frequency-Domain Reflectometry

    Publication Year: 2010 , Page(s): 3323 - 3328
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (510 KB) |  | HTML iconHTML  

    We show that the performance of phase-noise-compensated optical-frequency-domain reflectometry (PNC-OFDR) is affected by the acoustic phase noise caused by environmental acoustic perturbations applied to test fibers. When both the auxiliary interferometer and the fiber under test are insulated against acoustic perturbation, the theoretical spatial resolution is obtained. This means that a laser-induced phase noise compensation scheme with a concatenative reference method (CRM) works almost ideally and eliminates the phase noise even over a 40-km range, with 16-fold concatenation. We also reveal that even when we use a laser with a very narrow linewidth of a few kHz, the phase noise of the laser remains a dominant factor in performance degradation, and the CRM works effectively over the range. Test results for an actual fiber cable installed in underground show that there was no severe degradation in performance, and that PNC-OFDR sustained its unique high resolution in actual field use. View full abstract»

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  • Minimizing Photodiode Nonlinearities by Compensating Voltage-Dependent Responsivity Effects

    Publication Year: 2010 , Page(s): 3329 - 3333
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (782 KB) |  | HTML iconHTML  

    Two voltage-dependant responsivity effects, impact ionization and Franz-Keldysh oscillations, are shown to have opposing effects at certain wavelengths in p-i-n photodiodes. It is shown that these two effects can compensate each other and minimize photodiode nonlinearities when optimized with respect to wavelength and bias voltage. View full abstract»

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  • Broken-Ring-Based All-Solid Photonic Bandgap Fibers

    Publication Year: 2010 , Page(s): 3334 - 3339
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (526 KB) |  | HTML iconHTML  

    The design of bandgap-engineered all-solid photonic bandgap fibers based on a broken-ring structure is investigated in detail. Both density of states maps and Bloch mode field distributions are used to show how the bandgap structure can be engineered and a higher-order gap be greatly expanded by replacing the high-index germanium-doped rod in a repeating cell with a ring of several individual high-index rods. The strategy is that both the azimuthal and radial orders of the cladding LP modes can be controlled by the broken-ring parameters. In particular, the rod number determines the highest azimuthal order of the LP mode that is less affected by the broken-ring, and the bandgap width is largely affected by the rod size. The result of bandgap engineering is that the higher-order bandgap can be utilized to design all-solid photonic bandgap fibers with very broad transmission windows of 488 nm and 944 nm centered at 800 nm and 1550 nm, respectively, and with typical normal-zero-anomalous dispersion profiles. View full abstract»

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    Publication Year: 2010 , Page(s): 3340
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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