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Lightwave Technology, Journal of

Issue 20 • Date Oct.15, 2011

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Displaying Results 1 - 17 of 17
  • [Front cover]

    Publication Year: 2011 , Page(s): C1
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  • Journal of Lightwave Technology publication information

    Publication Year: 2011 , Page(s): C2
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  • Table of contents

    Publication Year: 2011 , Page(s): 3023 - 3024
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  • IR-UWB-Over-Fiber Systems Compatible With WDM-PON Networks

    Publication Year: 2011 , Page(s): 3025 - 3034
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1871 KB) |  | HTML iconHTML  

    Integrating an ultrawideband-over-fiber (UWBoF) system into a wavelength division multiplexing passive optical network (WDM-PON) is of great interest due to the high potential to provide high data-rate and flexible wired and wireless services with a favorable cost. In this paper, we perform a comprehensive study on an impulse radio UWBoF system compatible with the WDM-PON architecture implemented based on a photonic microwave bandpass filter. The bandpass filter is a two-tap delay-line filter implemented using either a polarization modulator (PolM) or a phase modulator (PM), which is used to simultaneously shape an electrical Gaussian-like pulse to an optical UWB pulse and reduce the out-band noise and interference. The features of the photonic microwave bandpass filters are theoretically studied. The photonic microwave bandpass filter based on a PolM would produce a chirp-free UWB signal, while the one based on a PM would generate a UWB signal that is insensitive to fiber dispersion. A single-channel UWBoF system with ON-OFF keying, biphase modulation, and pulse-position modulation without and with time hopping are experimentally studied. The experimental results agree well with the theoretical predictions. A four-channel UWBoF broadcasting network as well as a hybrid WDM-PON network to provide both wireless and wired services is also experimentally investigated. Results show that a conventional WDM-PON network could be easily upgraded to provide UWB services by incorporating the proposed photonic microwave bandpass filter. View full abstract»

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  • Robust and Integrated Grooming for Power- and Port-Cost-Efficient Design in IP Over WDM Networks

    Publication Year: 2011 , Page(s): 3035 - 3047
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3534 KB) |  | HTML iconHTML  

    Fueled by the growing resource crisis and potential economic incentives, significant research attention has recently been devoted to improving the power efficiency of IP over Wavelength-Division-Multiplexing (WDM) networks. Previous works on power savings in IP over WDM networks have required explicit knowledge of the traffic between each network node pair and the resource assignment of each fiber link. However, it is difficult to accurately estimate this information in live networks due to the inherent features of IP traffic, e.g., bursts, unpredictability and variability. Furthermore, the number of ports consumed in Optical Cross-Connects (OXCs) trends to grow due to the use of traffic grooming and optical bypasses for power savings. Therefore, it is necessary to achieve joint power efficiency and port savings in live IP over WDM networks where the traffic between each network node pair and resource assignment of each fiber link are not known in advance. Since the problem of grooming, routing and wavelength/waveband assignment is NP-hard, a new heuristic approach, the Robust and Integrated Grooming (RIG) algorithm, is proposed in this paper. RIG uses a novel metric, a power ratio defined by the power consumed over the power saved, to evaluate the power efficiency. By determining the Traffic Distribution Vector (TDV) with the lowest power ratio using the Minimizing Power Ratio First (MPRF) method, the previously unknown information can be acquired. By performing traffic matrix transformations, we construct a green optical virtual topology to groom connection demands into established lightpaths using Hybrid Grooming Schemes (HGSs) for power efficiency and waveband switching for port savings. The simulation results demonstrate that RIG can, on average, achieve power efficiency and port savings of 15% and 32%, respectively, compared to state-of-the-art robust grooming methods. To the best of our knowledge, this paper is the first work addressing robust and integrated - - grooming for power- and port-cost-efficient design in IP over WDM networks. View full abstract»

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  • Rotation Sensitivity of Gyroscopes Based on Distributed-Coupling Loop Resonators

    Publication Year: 2011 , Page(s): 3048 - 3053
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (285 KB) |  | HTML iconHTML  

    This paper reports a theoretical study of a recently proposed coupled-resonator optical waveguide (CROW) gyroscope consisting of a Sagnac interferometer in which light is coupled between adjacent loops in the coil. Simulations show that after optimization, this gyroscope is less sensitive to rotation than a conventional resonant fiber-optic gyroscope (RFOG) made of a single loop. Instead, the sensitivity decreases as the number of loops is increased. The fundamental reason is that in both types of sensors, the sensitivity is proportional to the group delay, and the maximum achievable group delay is limited in the same manner by loss. In addition, this CROW gyroscope utilizes multiple resonators instead of one, so it is much harder to stabilize against external perturbations. The RFOG still stands as the ideal candidate for a compact resonant gyroscope. View full abstract»

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  • Silicon-on-Insulator Nanowire Resonators for Compact and Ultra-High Speed All-Optical Wavelength Converters

    Publication Year: 2011 , Page(s): 3054 - 3060
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1493 KB) |  | HTML iconHTML  

    We present the development of application-specific silicon-on-insulator SOI nanowire ring and racetrack resonators designed to assist semiconductor optical amplifier (SOA)-based all-optical wavelength conversion. We demonstrate the fabrication of fix resonance racetrack resonators exhibiting coupling gaps as low as 160 nm and tunable ring resonators with coupling gaps <; 90 nm. The resonators are cascaded after commercial 40 Gb/s SOAs to realize chirp filtering of the optical data signals through high-resolution spectral sampling. We experimentally demonstrate inverted and non-inverted SOI resonator-assisted all-optical wavelength conversion at 40 Gb/s and 160 Gb/s with power penalties <; 3 dB. View full abstract»

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  • Impact of Third-Order Intermodulation on the Performance of Subcarrier Multiplexed Quantum Key Distribution

    Publication Year: 2011 , Page(s): 3061 - 3069
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1716 KB) |  | HTML iconHTML  

    This paper extends the analysis presented in a previous contribution to account for the effect of third-order intermodulation distortion in the system quantum bit error rate attainable in subcarrier multiplexed quantum key distribution (SCM-QKD) systems, showing that under practical conditions this effect can be safely neglected. When the unconditionally secure key distribution rate is computed for BB84 SCM-QKD systems based on weak coherent pulses and strong reference, it is found a per-channel additional decrease due to nonlinear distortions as low as 1% when compared to the dedicated nonmultiplexed BB84 key distribution channels operated under the same conditions. View full abstract»

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  • Block-Wise Digital Signal Processing for PolMux QAM/PSK Optical Coherent Systems

    Publication Year: 2011 , Page(s): 3070 - 3082
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2793 KB) |  | HTML iconHTML  

    In polarization multiplexing based coherent optical transmission, two main kinds of impairements have to be counter-acted: 1) the inter-symbol interference generated by the chromatic dispersion and the polarization mode dispersion and 2) the frequency offset. Usually adaptive approaches are carried out to mitigate them. Since the channel is very slowly time-varying, we propose to combat these impairements by using block-wise methods. Therefore, we introduce two new algorithms: the first one is a block-wise version of blind time equalizer (such as CMA), and the second one estimates the frequency offset in block-wise way. These algorithms are suitable for PSK and QAM constellations. By simulation investigations, we show that they outperform the standard approach in terms of convergence speed only at a moderate expense of computational load. We also experimentally evaluate their performance using 8-PSK real data traces and off-line processing which takes into account other physical impairments such as phase noise and non-linear effects. View full abstract»

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  • Slow Light Property Improvement and Optical Buffer Capability in Ring-Shape-Hole Photonic Crystal Waveguide

    Publication Year: 2011 , Page(s): 3083 - 3090
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1883 KB) |  | HTML iconHTML  

    Flatband slow light in a ring-shape-hole photonic crystal waveguide (RPCW) has been theoretically investigated. Numerical results show that both the outer and inner radii of the first two rows of holes adjacent to the defect have much affect on slow light properties. Therefore, by appropriately modifying the outer and inner radii of the ring-shaped holes, the slow light property is successfully optimized. Then we further enlarge the flat bandwidth by introducing the oblique structure. The negligible dispersion bandwidths ranging from 3.57 to 24.67 nm for group indexes from 28 to 115 are obtained, respectively, which is effectively improved if compared with other RPCW structures in previous works. Moreover, we also discussed the buffer capability and signal transmission characters of the RPCW. The result shows that the proposed structure has considerable potential for optical buffering applications. View full abstract»

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  • Multiheterodyne Detection for Spectral Compression and Downconversion of Arbitrary Periodic Optical Signals

    Publication Year: 2011 , Page(s): 3091 - 3098
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1616 KB) |  | HTML iconHTML  

    Optical frequency combs are used as local oscillators for the measurement and analysis of unknown optical waveforms with periodic time domain structures. Experimental results obtained by heterodyning pulsed and phase-modulated laser sources are presented. The analysis is then extended to the heterodyning and sampling of bandlimited incoherent light sources. It is shown theoretically and experimentally that the correlations between photodetected white light at different times can generate RF interference that is sensitive to the optical phase. View full abstract»

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  • Photonic Time-Stretched Analog-to-Digital Converter Amenable to Continuous-Time Operation Based on Polarization Modulation With Balanced Detection Scheme

    Publication Year: 2011 , Page(s): 3099 - 3106
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1558 KB) |  | HTML iconHTML  

    In this paper, we show analytically and experimentally that a polarization modulator which supports TE and TM modes of opposite phase modulation indexes can be utilized to reject dispersion-induced even-order distortions in a photonic Time-Stretched Analog-to-Digital Converter (TS-ADC). The output of the polarization modulator propagates through a single dispersive channel. This makes the present scheme amenable to continuous operation. Based on the virtual time gating principle, the continuous-time RF signal is time-stretched by a factor of 4 and segmented into four channels prior to digitization. For a single channel, differential operation is achieved by using a polarization beam-splitter that generates complementary pulses which are fed to a balanced detector. The differential operation helps to reject dispersion-induced even-order distortions and the balanced detection assists in the suppression of second-order distortion as well as improving the signal-to-noise ratio (SNR) by 6 dB. Using a 10 bit electronic ADC with a sampling rate of 2 GSamples/s, we demonstrate digitization of RF signals up to a frequency of 950 MHz and obtain ~ 3.56 effective number of bits (ENOB) with a single channel at ~ 31.6% of the electronic ADC's peak-to-peak full scale voltage. With adequate backend digitizing hardware, a four-channel continuous-time TS-ADC with a sampling rate of 8 GSamples/s can be realized to handle RF frequencies as high as 4 GHz. View full abstract»

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  • Quality Factor of a Nanobowtie Antenna

    Publication Year: 2011 , Page(s): 3107 - 3114
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1301 KB) |  | HTML iconHTML  

    We present a rigorous formulation based on the Poynting's theorem in dispersive and lossy media to calculate the quality factor, material loss, radiation loss, and radiation pattern of an optical nanobowtie antenna using the finite-difference time-domain method. The quality factor obtained from our theory, 8.73, agrees well with the experimental data. Our results show that the radiation loss and material loss are comparable. The material loss mainly originates from the chromium rather than gold even though the nanobowtie antenna mostly consists of gold. In addition, due to the small gap and plasmonic mode confinement, the effective modal volume is ultrasmall [6.36 × 10-5(λ/neff)3], which significantly breaks the diffraction limit. View full abstract»

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  • Current trends in Terahertz Photonics and applications

    Publication Year: 2011 , Page(s): 3115
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  • IEEE/OSA Journal of Lightwave Technology

    Publication Year: 2011 , Page(s): 3116
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  • Journal of Lightwave Technology Information for authors

    Publication Year: 2011 , Page(s): C3
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  • Blank page [back cover]

    Publication Year: 2011 , 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