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Lightwave Technology, Journal of

Issue 6 • Date March15, 2013

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Displaying Results 1 - 25 of 31
  • 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): 837 - 838
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  • Effect of Color Center Absorption on Temperature Dependence of Radiation-Induced Attenuation in Optical Fibers at Near Infrared Wavelengths

    Page(s): 839 - 845
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (671 KB) |  | HTML iconHTML  

    In order to explain the contradictory results on the temperature dependence of the radiation-induced attenuation (RIA) in optical fiber, the temperature dependence of color center absorption was proposed as a complementary explanation. The temperature tests were conducted on the four prototype optical fibers after irradiation. During the temperature tests the RIA in the fibers at the near infrared (NIR) wavelengths was measured continuously. The temperature dependence of color center absorption was verified. The competition between the thermally color center annealing and the temperature-dependent absorption of color center was observed. The test results show that the temperature dependent absorption of the color center at NIR wavelengths is an important factor influencing the temperature dependence of RIA besides the thermally driven color center generation, conversion and annealing process. View full abstract»

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  • Range of Influence and Impact of Physical Impairments in Long-Haul DWDM Systems

    Page(s): 846 - 854
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    In long-haul dense wavelength-division multiplexing (DWDM) systems with periodic dispersion compensation and amplification, system performance is adversely affected by severe physical impairments due to fiber losses, dispersion and nonlinearity. Fiber modeling is a prerequisite for the development of physical impairment mitigation techniques to improve system performance. The distance between two interacting symbols in time and wavelength, i.e., the range of influence (RoI) of each physical impairment, plays an important role in the development of these mitigation techniques. In this paper, we use the Volterra series transfer function (VSTF) method to define impairment characteristic coefficients that capture intersymbol interference (ISI), self phase modulation (SPM), intrachannel cross phase modulation (IXPM), intrachannel four wave mixing (IFWM), cross phase modulation (XPM) and four wave mixing (FWM), to characterize the impact of these impairments individually on the system output. We then investigate the impact of system parameters, namely, duty cycle, spectral efficiency, frequency chirp, and span length, on the RoI for long-haul DWDM systems. View full abstract»

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  • Impact of Burst Size and Inter-Arrival Time in All-Optical Gain Clamping Amplification for Optical Burst Switched Networks

    Page(s): 855 - 859
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (590 KB) |  | HTML iconHTML  

    This paper considers an optical burst switching network of 16 WDM channels amplified by all-optical gain clamped erbium-doped fiber amplifier. Experimental and numerical investigations are carried out in order to determine the impact of the burst length and inter-arrival time in the performance of stabilized amplification. The results show that the design of synchronous burst networks should take into account the characteristics of the clamped amplifier, whereas for asynchronous transmission, the power ripples induced by the critical cases may be neglected. View full abstract»

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  • Experimental Investigation of the Optical Injection Locking Dynamics in Single-Section Quantum-Dash Fabry-Pérot Laser Diode for Packet-Based Clock Recovery Applications

    Page(s): 860 - 865
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    An experimental study of the dynamics of a quantum-dash Fabry-Pérot passively mode-locked laser diode is presented. Firstly, the switching on and off characteristic times of the mode-locking mechanism with pulsed biasing current are assessed. Secondly, the locking and unlocking characteristic times to the injection of a 10-Gbps pseudo-random binary sequence of nonreturn-to-zero data are determined. The dynamics is analysed through the instantaneous frequency of the ~40 GHz beat-tone signal measured at the output of the laser under investigation, which after a frequency down-conversion stage, is recorded by a real-time oscilloscope. Experimental results indicate that a time of 5 ns characterizes the establishment of the passive mode-locking mechanism for a pulsed biasing current. A time of 20 ns has been measured for the synchronization of the quantum-dash laser diode to the injected 10 Gbps data sequence. In addition, the mode-locked laser diode de-synchronizes and switches to the free-running condition in also 20 ns after a holding time of ~ 100 ns. View full abstract»

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  • High Resolution PNC-OFDR With Suppressed Fading Noise for Dispersive Media Measurement

    Page(s): 866 - 873
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1209 KB) |  | HTML iconHTML  

    We show that fading noise in phase-noise compensated optical frequency domain reflectometry (PNC-OFDR) can be effectively reduced by applying an optical comb light source without any degradation in the reflectometry performance. The optical comb light source provides broad wavelength tunability, which is required for the frequency shift averaging (FSAV) for fading noise reduction while maintaining a narrow linewidth of the fiber laser used as a seed lightwave. We also clarify that PNC-OFDR with a reference interferometer simultaneously compensates for both phase noise and group velocity dispersion (GVD) induced by wideband measurement and a dispersive medium. These PNC-OFDR functions enable us to realize a high accuracy measurement of Rayleigh scattering level with low fading noise and high spatial resolution over 10 km range. View full abstract»

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  • Distribution of Broadband Services Over 1-mm Core Diameter Plastic Optical Fiber for Point-to-Multipoint In-Home Networks

    Page(s): 874 - 881
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1191 KB) |  | HTML iconHTML  

    This paper presents a point-to-multipoint (P2MP) in-home optical network infrastructure based on 1-mm core diameter plastic optical fiber (POF). By employing passive POF splitters, converged broadband wired and wireless service transmission over a P2MP POF infrastructure is demonstrated. A gross 2.2 Gb/s fractional discrete multitone (DMT) and a 528-MHz ultra wideband (UWB) wireless signal distribution simultaneously to four end-users are successfully achieved with BER <; 10-3 and EVM <; 15.5% , respectively. Up to 50 m transmission distance is achieved using off-the-shelf optical components. This feasibility study on all-optical P2MP infrastructures presents a promising low-cost solution for high-speed in-home broadband communication. View full abstract»

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  • Highly Scalable Amplified Hybrid TDM/DWDM Array Architecture for Interferometric Fiber-Optic Sensor Systems

    Page(s): 882 - 888
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    We present a distributed amplified hybrid dense wavelength division multiplexing (DWDM) and time division multiplexing (TDM) array architecture for large scale interferometric fiber-optic sensor array systems. This architecture employs a distributed Erbium doped fiber amplifier (EDFA) scheme to decrease the distribution loss among multiplexed wavelengths, and employs TDM at each wavelength to increase the total number of sensors that can be supported. The first experimental demonstration of this system is reported including results which show the potential for multiplexing and interrogating up to 4096 sensors using a single telemetry fiber pair with good system performance. The number of interrogation sensors could be further increased by increasing the number of wavelength channels. These architectures would be of great importance in the application of systems requiring very large number of sensors with limited telemetry cabling. View full abstract»

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  • Splice-Free Fiber Laser Array

    Page(s): 889 - 895
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    We propose and investigate a novel splice-free fiber laser array architecture that uses a double-core fiber where one of the cores is active and the other is passive. Fiber tapers were implemented to transmit the light at the pump and signal wavelengths between cores. Experimental results on coupling between cores are presented for two different fibers. A two-element monolithic fiber laser array is demonstrated. View full abstract»

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  • Colorless Optical Transmitter for Upstream WDM PON Based on Wavelength Conversion

    Page(s): 896 - 902
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1077 KB) |  | HTML iconHTML  

    We propose and demonstrate a novel colorless optical transmitter based on all-optical wavelength conversion using a reflective semiconductor optical amplifier (RSOA) for upstream transmission in wavelength-division-multiplexed passive optical networks. The proposed colorless optical transmitter for the optical network unit is composed of an electro-absorption modulated laser (EML), an optical coupler, and an RSOA. Through cross-gain modulation in the RSOA, the upstream data from the EML pump light are imposed onto a continuous-wave probe light provided from the central office (CO). An optical delay interferometer at the CO tailors the chirp of the upstream signal to improve the bandwidth of the system and dispersion tolerance. The proposed upstream optical transmitter is based on the fast gain recovery of the RSOA governed by carrier-carrier scattering and carrier-phonon interactions. Thus, it can potentially operate at >; 10 Gb/s. Two separate wavelength bands are allocated, one for the pump signals and the other for the probe signals. Therefore, the proposed transmitter operates in a colorless manner since the EML can have any arbitrary wavelength within the pump band. We demonstrate the transmission of a 10.7-Gb/s upstream signal generated by the proposed scheme in a single-fiber loopback-configured network. The conditions for colorless operation of the proposed transmitter are investigated through experiment. View full abstract»

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  • Survivable Traffic Grooming in Elastic Optical Networks—Shared Protection

    Page(s): 903 - 909
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    This study investigates the survivable traffic grooming problem for elastic optical networks with flexible spectrum grid employing new transmission technologies. In such networks, instead of following the traditional fixed ITU-T wavelength grid, optical transponders are capable of properly tuning their rates, and consequently their spectrum occupation, by introducing the fine-granular spectrum unit, called a frequency slot. The number of contiguous frequency slots allocated to an optical path (i.e., lightpath) is adjusted to the current network flow. In this study, we propose a novel shared protection specific to elastic networks, namely, elastic separate-protection-at-connection (ESPAC). It not only provides traditional backup sharing, but also offers a new opportunity of spectrum sharing enabled by the elasticity of the transponders: 1) if the working paths of two connections are link disjoint physically, and 2) if their backup paths traverse two lightpaths which are adjacent on a fiber link, then the two backup lightpaths can share spectrum. The new opportunity of spectrum sharing is realized by using First-Fit to assign working traffic and Last-Fit to assign backup traffic, and allowing spectrum overlap between adjacent backup wavelengths. The elasticity of the transponder enables the expansion and contraction of the lightpaths, thus when a single failure occurs in the network, lightpaths carrying backup flows can be tuned to appropriate rates in such a way that the overlap spectrum is used by only one of the adjacent lightpaths. The results show ESPAC is very spectrum efficient in elastic network setting. View full abstract»

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  • Hybrid Photonic True-Time Delay Modules for Quasi-Continuous Steering of 2-D Phased-Array Antennas

    Page(s): 910 - 917
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1946 KB) |  | HTML iconHTML  

    Hybrid photonic true-time delay modules for phased-array antennas are designed and demonstrated. Continuously tunable true-time delay network based on highly dispersive photonic bandgap fiber (up to 2135 ps/nm/km at 1570 nm), combined with a programmable true-time delay network utilizing optical waveguide delay line and optical switches, provides the antenna with quasi-continuous steering ability. Far-field patterns are simulated and measured to confirm the squint-free beam steering. View full abstract»

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  • Information Rate of OFDM-Based Optical Wireless Communication Systems With Nonlinear Distortion

    Page(s): 918 - 929
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    In this paper, a piecewise polynomial function is proposed as a generalized model for the nonlinear transfer characteristic of the transmitter for optical wireless communications (OWC). The two general multicarrier modulation formats for OWC based on orthogonal frequency-division multiplexing (OFDM), direct-current-biased optical OFDM (DCO-OFDM) and asymmetrically clipped optical OFDM (ACO-OFDM), are studied. The nonlinear distortion of the electrical signal-to-noise ratio (SNR) at the receiver is derived in closed form, and it is verified by means of a Monte Carlo simulation. This flexible and accurate model allows for the application of pre-distortion and linearization of the dynamic range of the transmitter between points of minimum and maximum radiated optical power. Through scaling and DC-biasing the transmitted signal is optimally conditioned in accord with the optical power constraints of the transmitter front-end, i.e., minimum, average and maximum radiated optical power. The mutual information of the optimized optical OFDM (O-OFDM) schemes is presented as a measure of the capacity of these OWC systems under an average electrical power constraint. When the additional DC bias power is neglected, DCO-OFDM is shown to achieve the Shannon capacity when the optimization is employed, while ACO-OFDM exhibits a 3-dB gap which grows with higher information rate targets. When the DC bias power is counted towards the signal power, DCO-OFDM outperforms ACO-OFDM for the majority of average optical power levels with the increase of the information rate target or the dynamic range. The results can be considered as a lower bound on the O-OFDM system capacity. View full abstract»

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  • A Monotonic-Increasing-Thickness Model for Designing Cylindrically Diffractive Focusing Micromirrors and Micromirror Arrays

    Page(s): 930 - 935
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    In this paper, a monotonic-increasing-thickness model (MITM) is proposed for designing cylindrically diffractive focusing micromirrors (DFMs) and cylindrically diffractive focusing micromirror arrays (arrayed DFMs). Based on rigorous electromagnetic theory and the boundary element method, numerical results reveal that focal properties of the designed DFMs are significantly improved through replacing the traditional equal-thickness model (ETM) with the proposed MITM, especially in the case of small f -numbers. In addition, the superiority of the MITM to the ETM is demonstrated in designs of the arrayed DFMs. For interference effect in the arrayed DFMs, we present new explanations. View full abstract»

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  • Design and Analysis for a 850 nm Si Photodiode Using the Body Bias Technique for Low-voltage Operation

    Page(s): 936 - 941
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    This study presents a design of the body contact in an 850 nm Si photodiode (PD) fabricated using standard 0.18-μm CMOS technology, and presents a systematic investigation of its effects on PD performance. This study confirms a good PD performance within 3 V bias and the establishment of the body current by directly measuring the body current, PD capacitance, and photocurrents. The body current from the biasing body contact was designed to eliminate the slow diffusion photocarriers in the substrate and increase bandwidth. The highest responsivity of 1.2 A/W was obtained from the PD without the body current, with biasing in the avalanche region. Adding the body bias increased the optimal bandwidth from 2.51 to 3.11 GHz, but reduced responsivity. However, the operating bias of the Si PD in the avalanche region was high, making it unsuitable for practical applications. While biasing PD at a low 3 V with a coordinated body bias, a bandwidth of 2.46 GHz was obtained with an acceptable responsivity of 0.1 A/W to allow low-voltage operation. View full abstract»

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  • A Cognitive Quality of Transmission Estimator for Core Optical Networks

    Page(s): 942 - 951
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1089 KB) |  | HTML iconHTML  

    We propose a cognitive Quality of Transmission (QoT) estimator for classifying lightpaths into high or low quality categories in impairment-aware wavelength-routed optical networks. The technique is based on Case-Based Reasoning (CBR), an artificial intelligence technique which solves new problems by exploiting previous experiences, which are stored on a knowledge base. We also show that by including learning and forgetting techniques, the underlying knowledge base can be optimized, thus leading to a significant reduction on the computing time for on-line operation. The performance of the cognitive estimator is evaluated in a long haul and in an ultra-long haul network, and we demonstrate that it achieves more than 98% successful classifications, and that it is up to four orders of magnitude faster when compared with a non-cognitive QoT estimator, the Q-Tool. View full abstract»

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  • Data Transfer From RZ-OOK to RZ-BPSK by Polarization-Insensitive XPM in a Passive Birefringent Nonlinear AlGaAs Waveguide

    Page(s): 952 - 966
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    The polarization-insensitive data transfer of 10-Gb/s return-to-zero ON-OFF keying (RZ-OOK) to RZ-binary phase-shift keying (RZ-BPSK) has been successfully carried out for the first time, in a passive birefringent nonlinear Al0.18Ga0.82As waveguide, utilizing polarization-insensitive cross-phase-modulation (PI-XPM). A 10-9 bit-error-rate (BER) pre-amplified receiver sensitivity penalty of ≈2.2 dB relative to baseline RZ-BPSK was measured for PI-XPM, when the RZ-OOK pump was polarization-scrambled and the RZ-probe was launched at 40°. The probe's optimal launch angle for PI-XPM was significantly influenced by the anisotropy of the Al0.18Ga0.82As waveguide. View full abstract»

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  • Investigation Into Optical Performance of Fiber Connections With Imperfect Physical Contact

    Page(s): 967 - 974
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    We theoretically and experimentally investigated the optical performance of fiber connections with various air-filled gaps. Such gaps might occur when a fiber connection realized using physical contact (PC) fails unexpectedly resulting in imperfect PC. The experimental results suggested that the optical performance of these fiber connections depends on both wavelength and gap width. When the air-filled gap between the fiber ends is narrow (of wavelength order) the insertion loss increases between 0.0 and 0.6 dB. The return loss varies greatly and the worst value is about 8.7 dB. When the gap is much wider than the wavelength, the insertion losses are mainly affected by the radiation loss in the air-filled gap between the fiber ends and the return losses are close to 14.7 dB, which is the Fresnel reflection value at a fiber end in air. We also found that in the worst case the insertion and return losses for fiber connections with imperfect PC can deteriorate respectively to ~ 18 and 9.4 dB at a wavelength of 1.31 μm and ~ 17 and 9.9 dB at a wavelength of 1.55 μm. In addition, we studied the characteristics of multi-connected PC-type connectors with an air-filled gap. We discovered that the total returned light from multi-connected joints with an air-filled gap could deteriorate to 5.9 dB at worst for four-connected connectors. These results support the practical use of PC-type connectors in the construction and operation of optical network systems. View full abstract»

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  • Exploiting Two-Wavelength Switching Capability of Silicon Photonic Microrings

    Page(s): 975 - 981
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    Silicon photonic microrings have the capability of handling two wavelengths simultaneously and this capability does not exist in other types of photonic switching technologies, such as directional couplers or MEMS. Exploiting this two-wavelength switching capability has not been done before. In this paper, we use this capability to construct a new type of microring-based non-blocking optical interconnects. For a 4×4 network, the new architecture only needs four rings. In contrast, the conventional crossbar-based architecture requires 16 rings. For medium size switches, such as 8 ports or 16 ports, the new architecture also requires significantly fewer rings than conventional crossbar switches of the same sizes. View full abstract»

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  • Flexible Polymeric Tunable Lasers for WDM Passive Optical Networks

    Page(s): 982 - 987
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (926 KB) |  | HTML iconHTML  

    Flexible polymer waveguide with a Bragg reflection grating is incorporated to form an external cavity laser with a wide tuning range, and it is evaluated as a tunable light source for wavelength division multiplexing optical communication systems. The highly elastic property of polymer materials makes them suitable for producing a tunable Bragg reflector controlled by an imposed strain. The flexible tunable Bragg reflector is installed on a compact moving stage 6 connected to a piezoelectric motor. By applying a total strain of 60680 με (6.07%), wavelength tuning of 82 nm is achieved with a side-mode suppression ratio of 43 dB and a linewidth less than 0.1 nm. The tunable laser controlled by a microactuator exhibits long-term stability with a wavelength fluctuation of less than 0.1 nm. In the optical transmission experiment, various wavelengths are used to transmit the 2.5 Gb/s signal over 50 km, excellent performance was observed with a power penalty of 1 dB compared to the DFB laser. View full abstract»

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  • Bringing WDM Into Optical Static RAM Architectures

    Page(s): 988 - 995
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1592 KB) |  | HTML iconHTML  

    Optical RAM appears to be the alternative approach towards overcoming the “Memory Wall” of electronics, suggesting use of light in RAM architectures to enable ps-regime memory access times. In this communication we take advantage of the wavelength properties of optical signals to present new architectural perspectives in optical RAM structures by introducing the WDM principles in the storage area. To this end, we report on a 4 × 4 WDM optical RAM bank architecture that exploits a novel SOA-based multi-wavelength Access Gate (WDM-AG) and a dual wavelength SOA-based SET-RESET All-Optical Flip Flop (AOFF) as fundamental building blocks. The WDM-AG enables simultaneous random access to a 4-bit optical word encoded in 8 different wavelengths, allowing for the four AOFFs of each RAM row to effectively share the same Access Gate. The scheme is shown to support a 10 Gbit/s operation for the incoming 4-bit data streams, with a power consumption of 15 mW/Gbit/s for the WDM-AG and 120 mW/Gbit/s for the AOFFs. The proposed optical RAM architecture reveals that exploiting the WDM capabilities of optical components can lead to RAM bank implementations with smarter column/row encoders/decoders, increased circuit simplicity, reduced number of active elements and associated power consumption, while enabling for re-configurability in optical cache mapping. View full abstract»

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  • [Blank page]

    Page(s): 996
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  • 2013 IEEE International Reliability Physics Symposium (IRPS)

    Page(s): 997
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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