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Lightwave Technology, Journal of

Issue 3 • Date Feb.1, 2011

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Displaying Results 1 - 25 of 25
  • [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): 251 - 252
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  • First-Principles Full-Vectorial Eigenfrequency Computations for Axially Symmetric Resonators

    Page(s): 253 - 259
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (553 KB) |  | HTML iconHTML  

    Starting from the time-harmonic Maxwell's equations in cylindrical coordinates, we derive and solve the finite-difference (FD) eigenvalue equations for determining vector modes of axially symmetric resonator structures such as disks, rings, spheres and toroids. Contrary to the most existing implementations, our FD scheme is readily adapted for both eigenmode and eigenfrequency calculations. An excellent match of the FD solutions with the analytically calculated mode indices of a microsphere resonator provides a numerical confirmation of the mode-solver accuracy. The comparison of the presented FD technique with the finite-element method highlights the relative strengths of both techniques and advances the FD mode-solver as an important tool for cylindrical resonator design. View full abstract»

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  • The Study of Information Capacity in Multispan Nonlinear Optical Fiber Communication Systems Using a Developed Perturbation Technique

    Page(s): 260 - 264
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (168 KB) |  | HTML iconHTML  

    We study the information capacity for a multispan optical fiber transmission system with losses, dispersion, nonlinearity, and amplified spontaneous emission noise. A perturbation technique is developed to examine the information capacity, and a semianalytic expression of the conditional probability distribution function is determined initially. A novel semianalytical form of the information capacity was obtained, which can be extended to the wavelength division multiplexing optical fiber communication systems. Computer simulations are executed for various parameters of the transmission system. The studied results indicate that the capacity does not monotone increase with the input power and is affected by the nonlinear coefficient and bit rate prominently. View full abstract»

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  • Offline Impairment-Aware RWA and Regenerator Placement in Translucent Optical Networks

    Page(s): 265 - 277
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (834 KB) |  | HTML iconHTML  

    In translucent optical networks, the physical layer impairments degrading the optical signal are considered in the network planning. In this paper, we investigate the offline problem of routing and wavelength assignment (RWA) and regenerator placement (RP) in translucent networks, minimizing the lightpath blocking and regenerator equipment cost. We address two variants of the problem, which correspond to two different types of quality of transmission (QoT) estimators, called linear and nonlinear. In a nonlinear QoT, nonlinear impairments like crosstalk or cross-phase modulation, which account for the interferences from neighboring lightpaths in the network are explicitly computed. Then, the QoT estimated for a lightpath depends on the routes of other lightpaths in the network. In the linear QoT, the effects of the nonlinear impairments are overestimated and accumulated to the rest of the impairments in the QoT calculation. As a result, the QoT estimation of a lightpath solely depends on its route. For the linear case, we formulate an optimal integer linear programming model of the problem, to the best of the authors' knowledge, for the first time in the literature. Its simplicity allows us to test it for small- and medium-size networks. Also, we propose two heuristic methods, namely, lightpath segmentation and three-step, and a tight lower bound for the regenerator equipment cost. For the nonlinear QoT case, we propose a new heuristic called iterative RP (IRP). Both the IRP and three-step algorithms are designed to guarantee that no lightpath blocking is produced by signal degradation. This is a relevant difference with respect to earlier proposals. The performance and the scalability of our proposals are then investigated by carrying out extensive tests. Results reveal that the solutions obtained by the heuristic algorithms are optimal or close to optimal, and outperform the earlier proposals in the literature. View full abstract»

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  • Electronic Impairment Mitigation in Optically Multiplexed Multicarrier Systems

    Page(s): 278 - 290
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1055 KB) |  | HTML iconHTML  

    In order to improve the performance of optically multiplexed multicarrier systems with channel spacing equal to the symbol rate per carrier, we propose and systematically investigate an electronic signal processing technique to achieve near-interchannel crosstalk free and intersymbol-interference (ISI) free operation. We theoretically show that achieving perfect orthogonality between channels in these systems, together with ISI free operation as needed in generic communication systems, requires the shaping of the spectral profiles of not only the demultiplexing filter, but also the signal of each channel before demultiplexing. We develop a novel semianalytical method to quantitatively analyze the levels of residual crosstalk and ISI arising from nonideal system response in these systems. We show that by prefiltering the signal to ensure that the system impulse response before channel demultiplexing approaches the targeted condition, the residual crosstalk due to imperfect orthogonality can be significantly mitigated and the necessity for carrier phase control in single-quadrature format-based system can be relaxed. Further combining prefiltering and receiver-side postfiltering to adaptively trim the demultiplexing filter enhances the performance. The use of the combined digital signal processing (DSP) in coherent-detection quadrature phase-shifted keying (QPSK)-based optically multiplexed multicarrier system shows that this method outperforms conventional QPSK-based multicarrier system without DSP or with only receiver-side DSP, especially when the responses of the transmitter and the demultiplexing filter are not precisely designed and the sampling rate of the analogue-to-digital converter is not sufficiently high. In addition, the inclusion of ISI free operation, with this aspect similar to the reshaping method in conventional wavelength-division-multiplexing systems, allows the relaxation of the modulation bandwidth and chromatic dispersion compensation. View full abstract»

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  • Analysis of an Optical Fiber Coherent System Immune to Polarization Fluctuations Using Adaptive Detection

    Page(s): 291 - 297
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1413 KB) |  | HTML iconHTML  

    The light polarization fluctuations strongly affect the performance of coherent optical communication systems due to the fact that to recover the information contained in the phase of the signal beam, it is necessary to have interference with a reference beam. In the present work, a simple system based on the use of an optical fiber interferometer and two adaptive photodetectors, which is immune to polarization fluctuations provoked by the fiber in both signal and reference beams, is theoretically analyzed. In such study, two models of the optical fiber, the first with just one linear retarder and another more complex with an additional circular retarder, were used. The results for linearly polarized light in the Y axis direction showed that digital signal transmission received by the adaptive system is immune to polarization fluctuations (in both signal and reference beams) in a wide range of ellipticity and rotation variations. In particular, if TTL logic is used, a maximum fluctuation of 60% with respect to the maximum of the output signal would be allowed to transmit the information correctly, in this case, ellipticity and rotation variations could be up to ±30°. View full abstract»

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  • Green's Function Analysis of Electromagnetic Wave Propagation in Photonic Crystal Devices Using Complex Images Technique

    Page(s): 298 - 304
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (677 KB) |  | HTML iconHTML  

    An integral equation method employing complex images Green's functions is developed for analyzing different devices fabricated in 2-D dielectric photonic crystals. The integral equation is written in terms of the unknown equivalent current sources flowing on the surfaces of the periodic 2-D cylinders. The method of moments is then employed to solve for the unknown current distributions. The required Green's function of the problem is represented in terms of a finite summation of complex images instead of the conventional slowly converging infinite series. It is shown that when the field-point is far from the periodic sources, it is just sufficient to consider the contribution of the propagating poles in the structure. This will result in a summation of plane waves that has an even smaller size compared with the conventional complex images Green's function. This will enable us to analyze the dielectric periodic structures efficiently and accurately. The method is applied to a number of waveguide structures and its results are compared with the existing literature. View full abstract»

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  • Statistical Study of Graded-Index Perfluorinated Plastic Optical Fiber

    Page(s): 305 - 315
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (893 KB) |  | HTML iconHTML  

    Plastic fiber-based optical links have been proposed for a wide variety of high-speed short reach applications. Graded-index (GI) multimode plastic optical fiber (POF) that supports 10 Gb/s over 50 m is commercially available and 40 Gb/s over 100 m has been demonstrated. However, unlike single-mode fiber and like silica multimode fiber (MMF), GI POF exhibits a range of performance that depends on launch condition and the accuracy of the index profile. Here, we report on the first statistical study of a large set of GI POF. We examine >; 40 samples of 62.5 μm core POF with four different cabling types that represent current-generation commercially available POF. We assess performance in terms of the 10 GbE requirements and quantify loss, chromatic dispersion, differential modal delay, effective modal bandwidth (EMB), and eye closure penalty. We find that nearly all of the measured 100 m fibers support the strict 10 GbE vertical-cavity surface emitting laser source EMB requirement, and that many fibers can support >; 40 Gb/s over 100 m. We thus demonstrate that GI POF can reliably support 10 Gb/s and larger bit rates to distances of 100 m. View full abstract»

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  • Quantum Encryption Communication Over a 192-km 2.5-Gbit/s Line With Optical Transceivers Employing Yuen-2000 Protocol Based on Intensity Modulation

    Page(s): 316 - 323
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    A Y-00 transceiver for quantum encryption communication systems employing the Yuen-2000 protocol based on optical intensity modulation, which utilizes the quantum effect of coherent light has been developed and tested in field experiments. These experiments involved repeated transmission over a 192-km line on an existing commercial optical communication network with a bit-rate of 2.5 Gb/s based on STM-16 or OC-48. In addition, the affinity of the developed system for existing networks and communication protocols (Gigabit Ethernet and Fibre Channel) was examined. Subsequently, three optical fiber amplifiers were inserted as intermediate repeaters to give a non-repeated transmission distance of 48 km. The bit error rate after 192-km transmission was 10-12 with an optical power of -19.4 dBm at the receiving end. In addition, it was confirmed that if an eavesdropper increased the received optical power, the bit error rate converged to about 5 × 10- 1 and the identification of the true signal levels was virtually impracticable. These experimental results confirmed the high affinity between the Y-00 system and existing optical commercial networks and protocols used in the fundamental experiments. It was also apparent that the realization of highly secure optical communication networks was feasible. The performance of the Y-00 transceiver can be expected to improve to meet the strictest security evaluation. View full abstract»

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  • Coincidence Rates for Photon Pairs in WDM Environment

    Page(s): 324 - 329
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    We demonstrate the flexibility that a wavelength selective switch could offer to bandwidth provisioning of potential multi-user quantum key distribution networks based on entangled pair sources. We derive an analytical expression relating the coincidence detection rates of the photon pairs to the switch bandwidth characteristics. Experimentally measured coincidence rates verify the theory in three distinct network configurations. View full abstract»

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  • Wavelength and Polarization Dependences of Fused Fiber Couplers

    Page(s): 330 - 334
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1127 KB) |  | HTML iconHTML  

    Fused fiber couplers were fabricated by controlling the coupler waist profile, and the wavelength and the polarization dependences against the waist profile were investigated experimentally. In case of the strongly fused coupler, the coupling is a little stronger for the -polarized light than the -polarized light, and the wavelength dependence increases with fusing more strongly in spite of the shorter effective coupler length. In case of the weakly fused coupler having a dumbbell profile with a narrow neck, the wavelength and the polarization dependences increase rapidly with narrowing the neck, and the wavelength dependence and the coupling become much larger for the -polarized light. The wavelength dependence becomes smallest around a dumbbell profile with the aspect ratio of 1.94. View full abstract»

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  • Laser-Self-Mixing Fiber Sensor for Integral Strain Measurement

    Page(s): 335 - 340
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (577 KB) |  | HTML iconHTML  

    Laser-self-mixing has been successfully applied to measuring both mechanical and thermal deformations in single-mode optical fibers attached to a solid bar. Strain resolution of has been achieved in a continuous range spanning three orders of magnitude. Temperature compensation is not necessary if deformations/vibrations occurred on a time scale faster than environmental thermal changes. A calibrated fiber thermometer has been implemented to correct for the temperature induced phase drift in case of thermal deformations. View full abstract»

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  • Theoretical Study of Optical Fiber Raman Polarizers With Counterpropagating Beams

    Page(s): 341 - 347
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    The theory of two counter-propagating polarized beams interacting in a randomly birefringent fiber via the Kerr and Raman effects is developed and applied to the quantitative description of Raman polarizers in the undepleted regime. Here Raman polarizers, first reported by Martinelli, are understood as Raman amplifiers operating in the regime in which an initially weak unpolarized beam is converted into an amplified fully polarized beam towards the fiber output. Three parameters are selected for the characterization of a Raman polarizer: the degree of polarization of the outcoming beam, its state of polarization, and its gain. All of these parameters represent quantities that are averaged over all random polarization states of the initially unpolarized signal beam. The presented theory is computer friendly and applicable to virtually all practically relevant situations, including the case of co-propagating beams, and in particular to the undepleted as well as the depleted regimes of the Raman polarizer. View full abstract»

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  • Rapid Reconfigurable OCDMA System Using Single-Phase Modulator for Time-Domain Spectral Phase Encoding/Decoding and DPSK Data Modulation

    Page(s): 348 - 354
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1006 KB) |  | HTML iconHTML  

    An optical-code-division-multiple-access (OCDMA) system with a novel modulation scheme for simultaneous generation of time-domain spectral phase encoding/decoding (SPE/SPD) and differential phase-shift keying (DPSK) data modulation that can be potentially rapidly reconfigured using only a single-phase modulator (PM) is proposed and experimentally demonstrated. The time-domain SPE is realized by stretching and compressing the ultrashort optical pulse through two-chirped fiber Bragg gratings with opposite dispersion and a high-speed PM for optical code (OC) generation and data modulation. The SPD has similar configuration as the SPE counterpart but using another PM synchronously driven by the complementary code pattern for OC recognition. Simulation investigation and experimental results both show that the code transition, dispersion mismatch between the encoding and decoding side, and the transmission fiber dispersion have detrimental effect on the en/decoding performance. In the experiment, 16-chip, 40-Gchip/s OC pattern and 2.5-Gb/s DPSK data modulation have been simultaneously generated using a single PM. The 2.5-Gb/s DPSK data have been successfully decoded and transmitted over 34 km fiber with BER <; 10-9 for five OCs. The proposed scheme employs similar setup for transmitter and receiver, exhibiting the potential to simplify the architecture of the whole system, and improve the flexibility and confidentiality of OCDMA system. View full abstract»

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  • QBER Estimation in QKD Systems With Polarization Encoding

    Page(s): 355 - 361
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    A model for quantum BER estimation in polarization encoded quantum key distribution systems is presented. Both TDM and WDM based polarization control schemes are analyzed. It is shown that TDM presents some important advantages when compared with the WDM control scheme. In WDM, the polarization decorrelation between the reference and data signals is an intrinsic and very limitative impairment. This effect has a contribution to quantum BER that increases with the propagation distance, and is highly dependent on the fiber polarization mode dispersion. In the TDM control scheme, the polarization decorrelation is less critical and other issues, like the single photon detector and feedback polarization control system performance tend to dominate. We show that for long distances the fiber losses represent the main contribution to the total quantum BER. Nevertheless, for distances shorter than 70 km and frequencies higher than 5 MHz the after pulse detections provide an important contribution to the total quantum BER. View full abstract»

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  • Positioning Error Prediction Theory for Dual Mach–Zehnder Interferometric Vibration Sensor

    Page(s): 362 - 368
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (546 KB) |  | HTML iconHTML  

    The positioning mean square error (MSE) prediction theory for dual Mach-Zehnder interferometric vibration sensor is proposed. The cross-correlation algorithm is considered. By taking into account the general noise time delay model, the impact of each noise term in output interference signal to ultimate positioning MSE is to our knowledge the first time be analyzed. An equivalent signal to noise ratio term for general noise time delay model is derived. It shows that incoherent phase noise (coming from polarization fading effect) makes an equivalent contribution to positioning MSE as additive noise under assumptions. In practical prediction, cross-correlation coefficient between two channel signals can be used to estimate positioning MSE. Simulation as well as experimental results are presented to corroborate the theory. View full abstract»

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  • Blank page

    Page(s): 369 - 370
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  • Biophotonics 1

    Page(s): 371
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  • Biophotonics 2

    Page(s): 372
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  • 23rd IEEE International Symposium on Power Semiconductors and ICs

    Page(s): 373
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    Freely Available from IEEE
  • 37th IEEE Photovoltaic Specialists Conference

    Page(s): 374
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    Freely Available from IEEE
  • Journal of Lightwave Technology Information for authors

    Page(s): C3
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  • Blank page [back cover]

    Page(s): C4
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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