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Lightwave Technology, Journal of

Issue 13 • Date July1, 2014

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Displaying Results 1 - 24 of 24
  • [Front cover]

    Publication Year: 2014 , Page(s): C1
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  • Journal of Lightwave Technology publication information

    Publication Year: 2014 , Page(s): C2
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  • Table of contents

    Publication Year: 2014 , Page(s): 2301 - 2302
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  • Fabrication, Characterization and Loss Analysis of Silicon Nanowaveguides

    Publication Year: 2014 , Page(s): 2303 - 2307
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (491 KB) |  | HTML iconHTML  

    Low loss silicon waveguides are the key to the realization of high performance photonic integrated circuits. In this paper, fabrication, characterization and loss analysis of silicon nanowaveguides are presented. Silicon nanowaveguides are fabricated on silicon-on-insulator (SOI) wafers with 0.13 μm complementary metal-oxide-semiconductor (CMOS) technology. To reduce the propagation loss, both photolithography and etching processes are optimized to make the waveguide sidewalls smooth. Propagation losses of 2.4 ± 0.2 and 0.59 ± 0.32 dB/cm are obtained at 1550 nm wavelength for TE and TM modes, respectively. A theoretical method is used to estimate the propagation losses for TE and TM modes. Scattering losses from both sidewalls and top/bottom surface are considered. The calculated results show that loss comes from sidewall roughness is the main source of propagation loss for TE mode while for TM mode, losses from both sidewall and top/bottom surface contribute comparably to the total propagation loss. The theoretically estimated propagation loss agrees well with the measured results. View full abstract»

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  • Cognitive, Heterogeneous and Reconfigurable Optical Networks: The CHRON Project

    Publication Year: 2014 , Page(s): 2308 - 2323
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3086 KB) |  | HTML iconHTML  

    High degree of heterogeneity of future optical networks, stemming from provisioning of services with different quality-of-transmission requirements, and transmission links employing mixed modulation formats or switching techniques, will pose a challenge for the control and management of the network. The incorporation of cognitive techniques can help to optimize a network by employing mechanisms that can observe, act, learn and improve network performance, taking into account end-to-end goals. The EU project CHRON: Cognitive Heterogeneous Reconfigurable Optical Network proposes a strategy to efficiently control the network by implementing cognition. In this paper we present a survey of different techniques developed throughout the course of the project to apply cognition in future optical networks. View full abstract»

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  • Transmission Performance of 256-Gb/s PDM-16QAM With Different Amplification Schemes and Channel Spacings

    Publication Year: 2014 , Page(s): 2324 - 2331
    Cited by:  Papers (1)
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    We experimentally investigate the performance of a 256-Gb/s polarization-division-multiplexed 16-ary quadrature-amplitude-modulation (PDM-16QAM) transmission system in dispersion uncompensated TeraWave SLA+ fiber spans using erbium-doped-fiber amplifiers (EDFAs), hybrid EDFA/Raman amplifiers, and all backward-pumped Raman amplifiers. The effects of 37.5- and 50-GHz channel spacings and cascaded optical add/drop multiplexers (ROADMs) on the system performance are studied. We find that when there are no ROADMs, hybrid EDFA/Raman amplifiers and all-backward-pumped Raman amplifiers can increase the reach by about 70% and 100%, respectively, compared to EDFA-only amplifiers, from 2000 to about 3500 and 4200 km, respectively, assuming 20% soft-decision forward-error-correction (SD-FEC) for the system with both 37.5- and 50-GHz channel spacings. We show that cascaded ROADMs have a small impact on the system with 50-GHz channel spacing, but can severely degrade the performance of the system with 37.5-GHz channel spacing and virtually eliminate the reach gain from Raman amplifiers in such systems due to large penalties and higher error floors induced by ROADM filtering effects. We also show that for the same number of channels, the system with 37.5- and 50-GHz channel spacings has similar performance when there are no ROADMs. View full abstract»

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  • Impact of Raman Scattered Noise from Multiple Telecom Channels on Fiber-Optic Quantum Key Distribution Systems

    Publication Year: 2014 , Page(s): 2332 - 2339
    Cited by:  Papers (1)
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    In this paper, we analyze the impact of the spontaneous Raman scattered noise generated from multiple optical classical channels on a single quantum key distribution channel, all within the telecom C-band. We experimentally measure the noise generated from up to 14 continuous-wave laser sources with different wavelengths using the dense wavelength division multiplexing (DWDM) standard, in both propagation directions in respect to the QKD channel, over different standard SMF-28 fiber lengths. We then simulate the expected secure key generation rate for a decoy-states-based system as a function of distance under the presence of simultaneous telecom traffic with different modulation techniques, and show a severe penalty growing with the number of classical channels present. Our results show that, for in-band coexistence, the telecom channels should be distributed as close as possible from the quantum channel to avoid the Raman noise peaks. Operation far from the zero dispersion wavelength of the fiber is also beneficial as it greatly reduces the generation of four-wave mixing inside the quantum channel. Furthermore, narrow spectral filtering on the quantum channels is required due to the harsh limitations of performing QKD under real telecom environments, with the quantum and several classical channels coexisting in the same ITU-T C-band. View full abstract»

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  • Mode Reduction for Efficient Modeling of Photonic Crystal Slab Structures

    Publication Year: 2014 , Page(s): 2340 - 2344
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    Rigorous numerical simulations for photonic crystal (PhC) slab structures and devices are difficult due to the complicated three-dimensional (3-D) geometry, high index-contrast, sharp edges, and possibly inhomogeneity at infinity. The approach based on expanding the field in 1-D vertical modes has great potential, but is currently limited by the relatively large number of modes needed for maintaining the accuracy of the solutions. In this paper, we show that if a single hole is first analyzed with the full set of vertical modes, the number of modes can be reduced to less than one third of the total in the main part of the computation. This leads to a speedup of more than 27 times. The method is illustrated by computing the transmission and reflection spectra for a PhC slab with a finite number of hole arrays. View full abstract»

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  • Analyses of Whispering Gallery Modes in Circular Resonators by Transmission Line Theory

    Publication Year: 2014 , Page(s): 2345 - 2352
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    Whispering gallery modes (WGMs) in circular resonators are investigated. Conformal transformation is used to transform circular resonators to more simplified structures. The principle of transverse resonance is utilized to calculate the resonant frequencies. Transmission line theory is applied to calculate the fields of electromagnetic waves. The resonant frequencies and field distributions in different high-Q resonators, including small resonators of several micrometers and large resonators of several millimeters in diameters, are investigated. The method provides a more efficient way to analyze the devices incorporating circular resonators. View full abstract»

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  • Reconfigurable Long-Reach UltraFlow Access Network: A Flexible, Cost-Effective, and Energy-Efficient Solution

    Publication Year: 2014 , Page(s): 2353 - 2363
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    In this paper, we propose and experimentally demonstrate a reconfigurable long-reach (R-LR) UltraFlow access network to provide flexible dual-mode (IP and Flow) service with lower capital expenditure (CapEx) and higher energy efficiency. UltraFlow is a research project involves the collaboration of Stanford, MIT, and UT-Dallas. The design of the R-LR UltraFlow access network enables seamless integration of the Flow service with IP passive optical networks deployed with different technologies. To fulfill the high-wavelength demand incurred by the extended service reach, we propose the use of multiple feeder fibers to form subnets within the UltraFlow access network. Two layers of custom switching devices are installed at the central office (CO) and remote node to provide flexibility in resource allocation and user grouping. With a centralized software-defined network (SDN) controller at the CO to control the dual-mode service, numerical analysis indicates that the reconfiguration architecture is able to reduce the CapEx during initial deployment by about 30%. A maximum of around 50% power savings is also achieved during low traffic period. The feasibility of the new architecture and the operation of the SDN controller are both successfully demonstrated on our experimental testbed. View full abstract»

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  • Energy-Efficient Future High-Definition TV

    Publication Year: 2014 , Page(s): 2364 - 2381
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    The rapidly growing IPTV market has resulted in increased traffic volumes raising concerns over Internet energy consumption. In this paper, we explore the dynamics of TV viewing behavior and program popularity in order to devise a strategy to minimize energy usage. We evaluate the impact of our strategy by calculating the power consumption of IPTV delivered over an IP-over-WDM network, considering both standard definition and high definition TV. Caches are used to reduce energy consumption by storing the most popular programs at nodes closer to the end user. We then use our knowledge of viewing behaviors to generate a time-driven content replacement strategy to maximize cache hit ratios and minimize energy use. We develop a mixed integer linear programming (MILP) model to evaluate the power consumption of the network while performing time-driven content replacements on caches and validate the results by simulation. Finally, we extend our model to perform content replacements on caches with sleep-mode capabilities which can save power by reducing their size. Our results show that time-based content replacements with such variable caches increase cache hit ratios and so reduces the overall power consumption by up to 86% compared to no caching. Our findings also show that more power savings are achieved for high definition TV compared to standard definition TV, so this strategy will be beneficial in the long term. View full abstract»

    Open Access
  • Analysis of the Coupling Mechanism in Asymmetric Fused Fiber Couplers

    Publication Year: 2014 , Page(s): 2382 - 2391
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    We investigated experimentally and numerically the coupling mechanism in asymmetric fused fiber couplers consisting of different single-mode fibers with unequal core diameter and numerical aperture. We increased the maximum coupled power by pretapering one of the fibers achieving a nearly complete power transfer at a specific pretaper length. Experimental results are compared to numerical results obtained by using our own 3-D FFT-based beam propagation method (BPM) algorithm. The numerical model explains qualitatively the coupler performance and allows to gain insight into the coupling mechanism. We discuss the influence of the fiber cores on the excited super-modes of the cladding structure. A modal decomposition of the light field is carried out in order to analyze the evolution of the super-modes and to discuss the influence of pretapering on the excitation of these modes. View full abstract»

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  • I/Q Channel Separated Baseband OFDM Optical Transmission Using Orthogonal Polarizations in IM/DD System

    Publication Year: 2014 , Page(s): 2392 - 2398
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    We have proposed baseband orthogonal frequency division multiplexing (OFDM) optical transmission technique using I/Q channel separation based on dual polarization with intensity modulation/direct detection (IM/DD). We experimentally verified performance of a proposed system in compare with intermediate frequency (IF)-upconverted OFDM system. In order to obtain better performance, adaptively modulated optical OFDM signal was used in this study. As a result, experimentally achieved maximum throughput after 50 km single mode fiber transmission was 28 Gbps with only using 4 GHz signal bandwidth. The proposed technique has relatively simple hardware structure and reduces computational complexity compared to other methods (IF upconversion or Hermitian symmetry) in IM/DD-based polarization multiplexed OFDM system. View full abstract»

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  • Numerical Analysis of Electro-Optical Modulators Based on the Amorphous Silicon Technology

    Publication Year: 2014 , Page(s): 2399 - 2407
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    This paper reports about an efficient method for the numerical simulation of the electrical and optical characteristics, in both steady state and transient conditions, of free carrier injection- or depletion-based electro-optical active devices, based on the low cost technology of hydrogenated amorphous silicon (a-Si:H) and related semiconducting alloys, like a-SiC:H. In particular, our experimental results, recently achieved for low-loss, birefringence-free, single-mode waveguide-integrated phase modulators, are used to tune the many simulation parameters and validate the mixed electro-optic simulation environment. The tool is used to design a Mach-Zehnder Interferometer (MZI)-based modulator enhancing the performances of previous realized devices. View full abstract»

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  • Long-Term Frequency Stabilization of an Optoelectronic Oscillator Using Phase-Locked Loop

    Publication Year: 2014 , Page(s): 2408 - 2414
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    We demonstrate an approach of long-term frequency stabilization of a single-loop optoelectronic oscillator (OEO) with a phase-locked loop (PLL). The OEO is frequency locked to a highly stable microwave reference via a PLL circuit with a PID regulator. With this approach, we obtained a highly stable 3.035-GHz microwave signal with phase noise of -65 dBC/Hz at 10-Hz offset frequency, and the frequency stability has reached 6.98 × 10-14 at average time of 1000 s. These experimental results show that the PLL-locked OEO is greatly improved in both long-term frequency stability and phase noise performance at low offset frequencies. Therefore, the PLL-locked OEO can be a strong candidate of highly stable, low phase noise microwave generators for microwave photonics applications. View full abstract»

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  • Highly Stable On-Chip Embedded Organic Whispering Gallery Mode Lasers

    Publication Year: 2014 , Page(s): 2415 - 2419
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    Chip-embedded organic resonator is fabricated with 2,5-Bis(4-biphenylyl)thiophene (BP1T) crystals encapsulated with polydimethylsiloxane (PDMS). Whispering gallery mode lasing is demonstrated in these on-chip embedded crystalline microresonators, without decline in the spectral properties, and performance in comparison to the unencapsulated devices. The encapsulated lasers exhibit quality factor (Q) as high as 1066, and lasing threshold is about 120 nJ (1.5 mJ/cm2). Meanwhile, with protection of the PDMS, operation lifetime of the laser is increased from 2.1 × 106 to 4.6 × 106 pulses. View full abstract»

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  • Carrier-Phase Estimation for 16-QAM Optical Coherent Systems Using QPSK Partitioning With Barycenter Approximation

    Publication Year: 2014 , Page(s): 2420 - 2427
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    This paper presents a hardware-efficient carrier phase estimator with high-linewidth tolerance for 16-QAM optical coherent systems. The laser phase noise is estimated using quaternary phase-shift keying (QPSK) partitioning complemented with a low complexity angle-based barycenter approximation as opposed to the classical Viterbi and Viterbi algorithm. The various stages necessary for partitioning and removing the modulation on the received symbols for carrier phase recovery are presented. We show that the phase offset in the middle ring for a 16-QAM constellation can be removed through a simple comparison with the symbols lying on the inner and outer rings of the constellation thus enabling all the symbols to be efficiently utilized for carrier phase recovery. We assess the performance of different filter structures for 16-QAM with filter half width 8 and 16. Simulation results demonstrate that combined linewidth symbol duration product Δν · Ts of 10-4 is tolerable at the target BER of 10-2 and 10-3 when using the barycenter algorithm. Finally, carrier phase recovery in a 16-QAM experiment is investigated to validate the performance of the proposed algorithm. View full abstract»

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  • Optical Aging of Chalcogenide Microstructured Optical Fibers

    Publication Year: 2014 , Page(s): 2428 - 2432
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    The evolution with time of optical transmission of chalcogenide microstructured optical fibers has been studied. Microstructured optical fibers with “grapefruit” geometry (six holes) have been prepared from four glass compositions (Te20As30Se50, As38Se62, Ge10As22 Se68, and As40S60). Optical aging has been investigated by means of attenuation measurements carried out for each fiber. Fibers were stored in air between measurements. Transmission spectra show absorption bands due to O-H bonds and molecular water. Aging kinetics vary with glass compositions. For As40S60 glass, the O-H absorption band appears 2 h after the drawing step, while for Te20As30Se50 glass that band is observed after an aging period as long as 21 months. View full abstract»

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  • MZI-Semiconductor-Based All-Optical Switch With Switching Gain

    Publication Year: 2014 , Page(s): 2433 - 2439
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    In this paper, we propose and design a novel all-optical switch that exhibits switching gain, based on feasibly realizable symmetric passive Mach-Zehnder interferometer with direct bandgap active arms. The switching is based on the absorption modulation of active arms through carrier depletion by a weak data pulse to switch a stronger pump beam. The proposed switch does not require electrical driving, and because of switching gain, it may not require energy-consuming re-shaping and re-amplification stages. Hence, the power requirement is significantly low. We show that by suitably designing the length of the active arms, operating wavelength and operating intensity of the pump beam, a switching gain >2 can be achieved when input signal pulse is less than 1/8× the strength of pump beam. We also show that the slow switch-off time caused by carrier band-filling is circumvented by using an additional delayed signal pulse to deplete carriers in both arms at a faster switch-on rate. With an inherent switching gain, low power operation and a switching speed that can reach ~100 Gbps, it could be a scalable and feasible solution to large scale broadband switching and wavelength conversion for silicon photonics. View full abstract»

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  • [Blank page]

    Publication Year: 2014 , Page(s): B2440
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  • Open Access Publishing

    Publication Year: 2014 , Page(s): 2441
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  • IEEE Xplore Digital Library

    Publication Year: 2014 , Page(s): 2442
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  • Journal of Lightwave Technology information for authors

    Publication Year: 2014 , Page(s): C3
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  • [Blank page - back cover]

    Publication Year: 2014 , 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.

Full Aims & Scope

Meet Our Editors

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