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Lightwave Technology, Journal of

Issue 6 • Date June 2003

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Displaying Results 1 - 22 of 22
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  • Generation of customized ultrahigh repetition rate pulse sequences using superimposed fiber Bragg gratings

    Page(s): 1490 - 1498
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (569 KB) |  | HTML iconHTML  

    We propose and experimentally demonstrate the use of superimposed fiber Bragg gratings (FBGs) as amplitude or phase filtering stages for generating ultrahigh-repetition-rate optical pulse bursts from a single ultrashort pulse. This approach offers the advantages of a compact all-fiber solution and provides high flexibility in tailoring the temporal features of the generated pulse sequence, namely, the repetition rate, as well as the shape and duration of both the individual pulses and the temporal envelope of the burst. To demonstrate the capabilities of the proposed approach, we generate near-flat-topped optical pulse bursts with repetition rates as high as ≈170 GHz at a wavelength of 1.55 μm using uniform and linearly chirped superimposed FBGs. We show that superimposed linearly chirped FBGs are more energetically efficient and provide increased design flexibility than superimposed uniform FBGs. Our experimental results also show the robustness of the technique to imperfections in the grating structures and to variations in the input pulse quality. View full abstract»

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  • Reduction of fiber chromatic dispersion effects in fiber-wireless and photonic time-stretching system using polymer modulators

    Page(s): 1504 - 1509
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (431 KB)  

    We have investigated the general characteristics of the power penalty due to the fiber chromatic dispersion effects in both fiber-wireless and photonic time-stretching systems. Two different modulation schemes have been demonstrated to reduce this penalty using our novel polymer modulators incorporating a multimode interference (MMI) structure. A single-sideband (SSB) modulator configuration has almost completely eliminated this penalty without a bandwidth limit. A double-sideband (DSB) modulator configuration with an appropriate quadrature bias has also shown significant improvement in bandwidth limitations for a given fiber link length. View full abstract»

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  • High-precision characterization of single-mode optical fiber arrays

    Page(s): 1557 - 1561
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (466 KB) |  | HTML iconHTML  

    A precise method of measuring core center dispersion in single-mode fiber arrays is presented. This approach dispenses with the use of high-precision linear translation stages and is based on a direct comparison of the fiber core center position to a simple lithographically patterned template. Combining image recognition and efficient processing algorithm, the fiber-core center positions of fiber arrays can be determined with precision of order of 0.1 μm, in both longitudinal and transversal directions. Complementary information about the position of fibers within v-grooves as well as bending of multifiber arrays can be also obtained. View full abstract»

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  • Logarithmic wavelength demultiplexers

    Page(s): 1576 - 1583
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (510 KB)  

    A general approach for a full 1 × N demultiplexer using a tree of filter stages is proposed. The device architecture is compact, requiring at least N - 1 filter stages, and flexible, as each filter stage can be arbitrarily designed, with the only constraint of the half-band power property. The filters can be realized using any optical filtering techniques as thin-film interference, Bragg gratings, or planar delay-line circuits. The performances of the proposed architecture are illustrated with respect to different lattice-form finite impulse response (FIR) and infinite impulse response (IIR) filter stages, showing that the demultiplexer inherently presents low crosstalk and flat passband. A design example of a 1 × 4 demultiplexer consisting of three all-pass (AP) filters is compared with a generalized Mach-Zehnder interferometer (MZI) with four AP filters in its arms, showing that the two approaches achieve similar results. View full abstract»

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  • An effective method for blocking performance analysis of WDM all-optical networks

    Page(s): 1421 - 1434
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (776 KB)  

    We propose a rational approximation (RA)-based algorithm to perform the blocking analysis of circuit-switched all-optical networks. Our algorithm can be applied to large networks with various topologies and routing and wavelength assignment algorithms. It can be applied to optical networks with either full, sparse, or no wavelength conversion. We also propose fixed-path wavelength assignment algorithms for networks with balanced and unbalanced traffic. View full abstract»

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  • Dense wavelength-division multiplexing millimeter-wave-band radio-on-fiber signal transmission with photonic downconversion

    Page(s): 1510 - 1517
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (911 KB) |  | HTML iconHTML  

    Photonic downconversion (PDC) technique for dense wavelength division multiplexing (DWDM) millimeter-wave-band radio-on-fiber (ROF) uplink systems is investigated. The PDC technique is carried out for a lump of all uplink wavelength division multiplexing (WDM) ROF signals at a central station. Each channel is optically separated, photodetected, and demodulated individually without serious signal degradation due to the fiber dispersion effect. Error-free 25-GHz-spaced DWDM transmission and demultiplexing of two 60-GHz-band, 155-Mb/s differential phase-shift keying (DPSK) ROF signals over 25-km-long standard single-mode fiber (SMF) are experimentally demonstrated. View full abstract»

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  • Simultaneous suppression of third-order dispersion and sideband instability in single-channel optical fiber transmission by midway optical phase conjugation employing higher order dispersion management

    Page(s): 1465 - 1473
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (493 KB) |  | HTML iconHTML  

    In optical phase conjugation (OPC) systems, the third-order dispersion (TOD) of optical fibers and the nonlinear resonance at well-defined signal sideband frequencies called sideband instability (SI) mainly limit the transmission performance. We propose, for the first time, a scheme for simultaneous suppression of both TOD and SI in OPC systems using a periodic higher order dispersion-managed link consisting of standard single-mode fibers (SMFs) and reverse dispersion fibers (RDFs). Computer simulation results demonstrate the possibility of 200-Gb/s data transmission over 10 000 km in the higher order dispersion-managed OPC system, where the dispersion map is optimized by our system design strategies. View full abstract»

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  • Wavelength reuse for efficient packet-switched transport in an AWG-based metro WDM network

    Page(s): 1435 - 1455
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1391 KB) |  | HTML iconHTML  

    Metro wavelength-division multiplexed (WDM) networks play an important role in the emerging Internet hierarchy; they interconnect the backbone WDM networks and the local-access networks. The current circuit-switched SONET/synchronous digital hierarchy (SDH)-over-WDM-ring metro networks are expected to become a serious bottleneck-the so-called metro gap-as they are faced with an increasing amount of bursty packet data traffic and quickly increasing bandwidths in the backbone networks and access networks. Innovative metro WDM networks that are highly efficient and able to handle variable-size packets are needed to alleviate the metro gap. In this paper, we study an arrayed-waveguide grating (AWG)-based single-hop WDM metro network. We analyze the photonic switching of variable-size packets with spatial wavelength reuse. We derive computationally efficient and accurate expressions for the network throughput and delay. Our extensive numerical investigations-based on our analytical results and simulations-reveal that spatial wavelength reuse is crucial for efficient photonic packet switching. In typical scenarios, spatial wavelength reuse increases the throughput by 60% while reducing the delay by 40%. Also, the throughput of our AWG-based network with spatial wavelength reuse is roughly 70% larger than the throughput of a comparable single-hop WDM network based on a passive star coupler (PSC). View full abstract»

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  • Theoretical investigation of 8 × 10-Gb/s WDM signal transmission performance based on gain-equalized SOAs using backward Raman pumping at DCF

    Page(s): 1499 - 1503
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (374 KB)  

    We have theoretically investigated 8 × 10-Gb/s wavelength-division multiplexing (WDM) signal transmission characteristics based on semiconductor optical amplifiers (SOAs) with equalized gain using discrete Raman amplification (DRA). Gain equalization and low noise figures have been obtained by adjusting the backward Raman pumping power and wavelength at a dispersion compensating fiber (DCF) for each span. Bit-error-rate characteristics were calculated for 8 × 10-Gb/s WDM signal transmission over 6 × 40-km single-mode fiber (SMF) + DCF links with gain-equalized SOAs using DRAs at DCF. Approximately a 2.5-dB improvement of the receiver sensitivity was achieved by using SOAs and DRAs with optimized Raman pumping. One can easily upgrade the transmission length of a link based on SOAs with an appropriate backward pump laser at each DCF. View full abstract»

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  • Electrically tunable dispersion compensator with fixed center wavelength using fiber Bragg grating

    Page(s): 1568 - 1575
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (799 KB) |  | HTML iconHTML  

    We present the design and development of a novel tunable dispersion compensator with fixed center wavelength that is based on the electrical adjustment of the chirp of a fiber Bragg grating (FBG). Both temperature gradient and strain gradient are employed to adjust the chirp of the FBG jointly. The electrical current flowing through the taper on-fiber thin-film heater will introduce a temperature gradient on the FBG. The shrinkage of a negative thermal expansion coefficient (NTEC) ceramic due to the temperature rise will compress the tapered FBG mounted inside it, and this will introduce a strain gradient on the FBG. The center wavelength of the FBG will be kept fixed because the effect of temperature rise on the FBG and the effect of compression of the FBG will offset each other. Applying an electrical power of less than 0.68 W, we demonstrate a linearly chirped FBG whose dispersion can be continuously adjusted from -178 ps/nm to -302 ps/nm with a central wavelength shift of as small as 0.16 nm. View full abstract»

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  • Design and performance of very-high-density 60-fiber connectors

    Page(s): 1549 - 1556
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (409 KB) |  | HTML iconHTML  

    High-density, high-count mechanically transferable (MT)-type and multifiber push-on (MPO)-type connectors were constructed by using a monolithic 60-fiber ferrule that aligns five stacked 12-fiber ribbons. The MT- and MPO-type connectors have high packaging densities of 286 and 40 fibers/cm2, respectively. We fabricated both types of connector. The average insertion loss of the MT type was 0.30 dB and that of the MPO type 0.70 dB, with and without index-matching material, respectively. View full abstract»

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  • Modeling and simulation of photonic devices by generalized space mapping technique

    Page(s): 1562 - 1567
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (459 KB) |  | HTML iconHTML  

    The generalized space mapping (GSM) technique is employed for modeling and simulation of photonic devices. The mapping is established between the parameter spaces of coarse and fine models so that accuracy of the coarse model is significantly improved for a given range of parameters. To demonstrate the usefulness of this technique, modeling and simulation of an optical waveguide facet is used as an application example. Two methods are adopted for the coarse model, i.e., the transfer matrix method (TMM) and the free space radiation mode (FSRM) method. The time-intensive and accurate finite-difference time-domain (FDTD) method is used as the fine model for model calibration. The mapping-enhanced coarse models show significant improvement in terms of accuracy. Further, a criterion is established to measure the accuracy of the coarse models. It is shown that the FSRM is one order of magnitude more accurate than the TMM for the TE case, however, the two methods have almost the same level of accuracy for the TM case. View full abstract»

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  • An optimized InGaAsP/InP polarization converter employing asymmetric rib waveguides

    Page(s): 1544 - 1548
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (507 KB) |  | HTML iconHTML  

    In this paper, we report on the design of a compact (≈ 226 μm) on-chip InGaAsP/InP polarization converter based on an asymmetric rib waveguide. Our theoretical analysis demonstrates that the device displays a conversion efficiency of < -25 dB (> 99.68% power conversion between orthogonal polarization) at 1550-nm wavelength with a nearly flat response over the optical C band. Regarding fabrication tolerances, we predict that the most sensitive design parameter is the waveguide width as the conversion efficiency drops to 10 dB for a deviation of ± 0.1 μm from the optimized value. View full abstract»

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  • Performance analysis of 10-μm-thick VCSEL array in fully embedded board level guided-wave optoelectronic interconnects

    Page(s): 1531 - 1535
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (750 KB) |  | HTML iconHTML  

    We introduce a simple and effective heat sink structure for thin-film vertical cavity surface emitting lasers (VCSELs) in fully embedded board level guided-wave interconnects. A 50% quantum efficiency increase is experimentally confirmed for the 10-μm thin-film VCSELs. The thermal resistance of a 1 × 12 embedded thin-film VCSEL array in printed circuit board (PCB) is further analyzed. The experimental results show an excellent match with the simulated results. The 10-μm-thick VCSEL had the lowest thermal resistance and the highest differential efficiency compared to 250-, 200-, 150-, and 100-μm-thick VCSELs. A substrate removed VCSEL can be used in fully embedded board level optical interconnects without special cooling techniques. View full abstract»

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  • Analysis and design of integrated optical mirrors in planar waveguide technology

    Page(s): 1584 - 1591
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (623 KB) |  | HTML iconHTML  

    We demonstrate integrated optical mirrors in alumina-based waveguides on oxidized silicon substrates. The finite-element method (FEM) is employed for the design of mirrors operating between 1.31 and 1.55 μm at both fundamental polarizations. Excellent agreement between measurement and simulation is achieved for the dispersion behavior of the device. The highly polarization-dependent scattering loss at the reflecting interface is well predicted considering approximate values for the reactive ion etching (RIE) process induced surface roughness. View full abstract»

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  • Comparison of the Jones matrix analytical models applied to optical system affected by high-order PMD

    Page(s): 1456 - 1464
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (501 KB)  

    The analytical models for the Jones matrix of an optical fiber affected by high-order polarization-mode dispersion (PMD) are studied in an original comparative analysis with the purpose of finding a useful, precise, and stable tool for the system performance evaluation. First, a preliminary deterministic study is done to explain how the conceptual difference among the models reflects onto their representation of the fiber PMD effects in terms of Jones matrix coefficients and dispersion vector. Then, the analytical models with PMD up to third order are exploited for the calculation of the outage probability on the sensitivity penalty at the receiver, and the results obtained are compared with those of the discrete random wave-plate numerical model, assumed as a faithful description of the real fiber. Two different approaches are used for the outage probability evaluation: an analytical method, which is precise and faster but can only be used with PMD parameters up to second order, and a semi-analytical method that allows a comparison of the numerical and analytical results with homogeneity, when the statistics of high-order PMD are not known. The analytical model, which describes the dispersion vector as rotating on a circumference in the Stokes space, is found to be the most accurate in the system performance computation. View full abstract»

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  • Effective electromagnetic shielding of plastic packaging in low-cost optical transceiver modules

    Page(s): 1536 - 1543
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (920 KB) |  | HTML iconHTML  

    A low-cost plastic package of the standard 1 × 9 type with effective electromagnetic (EM) shielding ability is developed. Optical transceiver modules with transmission rates of 155 Mb/s and 1.25 Gb/s are tested to evaluate the EM shielding against emitted radiation from the plastic packaging. The results show that the packaged optical transceiver modules exhibit shielding effectiveness (SE) of over 20 dB. The EM shielding properties of plastic materials consisting of nylon66 and liquid crystal polymer (LCP) with carbon fiber reinforced are investigated. The effects of weight percentage of fibers, carbon fiber length, and material thickness on the SE of the plastic composites are studied both from the plane-wave and near-field sources approaches. The packaged plastic optical transceiver modules with their good SE are suitable for use in low-cost and low electromagnetic interference (EMI) Gigabit Ethernet lightwave transmission systems. View full abstract»

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  • Reducing crosstalk and signal distortion in wavelength-division multiplexing by increasing carrier lifetimes in semiconductor optical amplifiers

    Page(s): 1474 - 1485
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (675 KB) |  | HTML iconHTML  

    A simple theory for the crosstalk in multichannel wavelength-division multiplexing (WDM) communication systems caused by the cross gain saturation in semiconductor optical amplifier (SOA) is developed. It is shown that increasing the carrier recombination lifetime while reducing the differential gain in the SOA greatly mitigates the crosstalk. An SOA using type-II quantum wells with reduced recombination probability is designed, and its characteristics are numerically modeled for a number of different WDM systems. It is shown that when used as a preamplifier or in local/metro networks with a small number of amplifiers, error-free transmission can be achieved with the type-II SOA. View full abstract»

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  • Design of two-section DBR laser operating at ITU frequencies only by grating current tuning

    Page(s): 1524 - 1530
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (537 KB) |  | HTML iconHTML  

    A new design procedure for multisection distributed Bragg reflector (DBR) lasers is presented and it has been applied to the design of two-section devices lasing at ITU frequencies only by grating current injection. The validity of the solution has been compared with respect to a nonoptimized structure and the possibility to compensate the device realization errors with only a fixed heat sink temperature change equal for all the channels has been analyzed. View full abstract»

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  • Ghost-pulse generation suppression in phase-modulated 40-Gb/s RZ transmission

    Page(s): 1486 - 1489
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (254 KB)  

    40-Gb/s return-to-zero (RZ) transmission in strong dispersion maps is limited by single-channel four-wave mixing. Appropriate phase modulation of the signal suppresses generation of the ghost pulses. Duobinary and modified duobinary encoding produce cancellation of nonlinear interaction while carrier-suppressed RZ generates perturbations that add up coherently. View full abstract»

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  • RIN transfer measurement and modeling in dual-order Raman fiber amplifiers

    Page(s): 1518 - 1523
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (552 KB)  

    A numerical analysis is presented that models the transfer of relative intensity noise (RIN) from the first- and second-order pump lasers to the signal radiation in dual-order Raman fiber amplifiers. Measurements are presented of the first- and second-order RIN transfer functions for co- and counter-propagating fiber amplifiers. The second-order RIN transfer function is similar to that found in single-order Raman fiber amplifiers and the first-order transfer function is approximately 15 dB less than the second-order transfer function. The impact of the RIN transfer from the first- and second-order pump lasers to the signal radiation on the system performance is examined and estimates for the required pump laser RIN levels are presented. View full abstract»

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Aims & Scope

The Journal of Lightwave Technology contains articles on current research, applications and methods used in lightwave technology and fiber optics.

Full Aims & Scope

Meet Our Editors

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