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Selected Topics in Quantum Electronics, IEEE Journal of

Issue 5 • Date Sept.-Oct. 2010

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Displaying Results 1 - 25 of 57
  • [Front cover]

    Publication Year: 2010 , Page(s): C1
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  • IEEE Journal of Selected Topics in Quantum Electronics publication information

    Publication Year: 2010 , Page(s): C2
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  • Table of contents

    Publication Year: 2010 , Page(s): 1045 - 1047
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  • Introduction to the Issue on Enabling Technologies for Digital Optical Communication Systems

    Publication Year: 2010 , Page(s): 1048 - 1050
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  • Optical Intersatellite Communication

    Publication Year: 2010 , Page(s): 1051 - 1057
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (724 KB) |  | HTML iconHTML  

    This paper describes the achievements in optical intersatellite communication based on technology developments that started in Europe (European Space Agency) more than 30 years ago. In 2001, the world-first optical intersatellite communication link was established (between the SPOT-4 and Advanced Relay and TEchnology MIssion Satellite (ARTEMIS) satellites), proving that optical communication technologies can be reliably mastered in space. In 2006, the Japanese Space Agency (JAXA) demonstrated a bidirectional optical link between its Optical Inter-Orbit Communications Engineering Test Satellite and ARTEMIS, and in 2008, the German Space Agency (DLR) established an intersatellite link between the near-field infrared experiment and TerraSAR-X satellites already based on the second generation of laser communication technology. View full abstract»

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  • Optical Communications for High-Altitude Platforms

    Publication Year: 2010 , Page(s): 1058 - 1070
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (778 KB) |  | HTML iconHTML  

    This paper contains a review of technologies, theoretical studies, and experimental field trials for optical communications from and to high-altitude platforms (HAPs). We discuss the pointing, acquisition, and tracking of laser terminals and describe how laser beams with low divergence can be used to transmit data at multi-Gigabits per second. Investigating the influence of the atmosphere, background light, and flight qualification requirements on system design, we explain why the data rates in free-space optical communications are still significantly below those possible in today's terrestrial fiber-based systems. Techniques like forward-error correction, adaptive optics, and diversity reception are discussed. Such measures help to increase the data rate or link distance while keeping the bit error ratio and outage probability of the optical HAP communication system low. View full abstract»

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  • Diversity Reception for Deep-Space Optical Communication Using Linear Projections

    Publication Year: 2010 , Page(s): 1071 - 1083
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (697 KB) |  | HTML iconHTML  

    A novel spatial diversity receiver for deep-space optical communication links is proposed. Using digital micromirror devices, the receiver optically computes linear projections of the turbulence-degraded focal-plane signal distribution onto an orthogonal binary basis. By using such projections, an estimate of the signal distribution is computed and updated adaptively to follow the time variations of the signal distribution. The estimate is used to perform selection combining, i.e., to select the portions of the focal plane that contain significant energy for symbol detection. The proposed receiver is less complex, requires less high-speed analog electronics and has lower preamplifier noise than a comparable multiple-detector array receiver. On the other hand, the proposed receiver requires more optical components and additional digital hardware to control the micromirror devices. Symbol error-rates (SERs) are simulated on a photon-counting channel and performance improvements about 2-5 optical decibels (dBo) over a conventional single-detector receiver are obtained at SER = 10-2. View full abstract»

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  • Improved Timing Resolution Single-Photon Detectors in Daytime Free-Space Quantum Key Distribution With 1.25 GHz Transmission Rate

    Publication Year: 2010 , Page(s): 1084 - 1090
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (253 KB) |  | HTML iconHTML  

    In free-space single-photon quantum key distribution (QKD), the error rate due to daytime background photons can be reduced with strong temporal filtering. In this case, the improvement in performance is determined by the receiver's ability to resolve signal-photon arrival times. We use fast clock recovery and commercially available single-photon detectors with timing resolution enhanced by additional electronic circuitry to implement temporal gating down to 50 ps in a free-space QKD system. The single-photon channel operates at 850 nm, and the improved timing resolution enables transmission rates of 1.25 GHz. We observe daytime quantum bit error rates of 0.04, which is less than one-third of the ungated error rate. We present the design and performance of the system and demonstrate its benefit to free-space QKD. View full abstract»

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  • Differential Phase-Shift Keying in Spatial Diversity Transmitters for Fade Mitigation

    Publication Year: 2010 , Page(s): 1091 - 1098
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (509 KB) |  | HTML iconHTML  

    We investigate the use of differential phase-shift keying (DPSK) in multiwavelength spatial diversity transmitters for mitigation of atmospheric fading. By selecting the transmitter wavelengths to coincide with the transmission peaks of the delay-line interferometer in the receiver, the only modification required to a standard DPSK receiver is a wider optical filter. We examine the wavelength separation required to minimize penalties from beating between the wavelengths and find that a separation of twice the data rate is sufficient for a four-wavelength system with narrow filtering. We also demonstrate a reduction in scintillation loss for a four-wavelength DPSK system in a fading channel. View full abstract»

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  • Advanced Photoreceivers for High-Speed Optical Fiber Transmission Systems

    Publication Year: 2010 , Page(s): 1099 - 1112
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1455 KB) |  | HTML iconHTML  

    The increasing demand for higher transmission capacity over the existing optical fiber infrastructures raises the interest in using more efficient optical modulation formats supported by new challenging component technologies. This paper describes the current status of integrated photoreceivers, thus highlighting the relationship between sophisticated optical transmission requirements and feasible technology achievements. View full abstract»

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  • InP Photonic Integrated Circuits

    Publication Year: 2010 , Page(s): 1113 - 1125
    Cited by:  Papers (25)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1739 KB) |  | HTML iconHTML  

    InP is an ideal integration platform for optical generation, switching, and detection components operating in the range of 1.3-1.6 m wavelength, which is preferred for data transmission in the most prevalent silica-based optical fiber. We review the current state of the art in advanced InP photonic ICs. View full abstract»

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  • Chirp Managed Laser and Applications

    Publication Year: 2010 , Page(s): 1126 - 1139
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1569 KB) |  | HTML iconHTML  

    The chirp managed laser (CML) is an alternative transmitter technology that allows a directly modulated laser (DML) to be used in high-performance applications with a smaller size, lower power consumption, less device complexity, and lower cost. The CML comprises a DML and an isolated, passive optical filter. A key feature of the CML is its large tolerance to fiber dispersion, reaching over 360 km transmission at 10 Gb/s in standard single-mode fiber without dispersion compensation. The combination of adiabatic chirp from the laser and filter edge response produces high extinction ratio pulses with nearly uniform phase, abrupt phase shifts at bit transitions, and a correlation between the 1 bits; 1 bits separated by odd number of 0 bits are out of phase. This results in destructive intersymbol interference after fiber transmission. Other applications of CML are generation of advanced modulation formats, such as return-to-zero (RZ) alternate mark inversion, and RZ differential phase-shift keying. Tunable CML using DFB array, and sampled grating deterministic bit rate (DBR) technologies for 10 Gb/s metro applications have now been demonstrated. A four-element DBR array CML has also been demonstrated for 100 Gb/s metro applications. This paper reviews the principle of operation of CML and its various applications, as well as recent advances in CML-based devices. View full abstract»

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  • Coherent synthesis of optical multilevel signals by electrooptic digital-to-analog conversion using multiparallel modulator

    Publication Year: 2010 , Page(s): 1140 - 1149
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (614 KB) |  | HTML iconHTML  

    This paper presents an electrooptic vector digital-to-analog converter (EO-DAC) for coherent synthesis of optical multilevel signals, such as quadrature-amplitude modulation (QAM) signals. For generation of an optical multilevel/QAM signal, the inphase (I) and quadrature (Q) components of a carrier lightwave should be orthogonally modulated in multi-levels. Conventionally, inphase-quadrature (IQ) orthogonal modulators have been utilized for this purpose. In the scheme, however, the symbol rate available for multilevel/QAM signals is limited, and it is difficult to obtain a clear constellation because of the difficulty involved in handling with electrical multilevel signals. The EO-DAC employing multiparallel modulator, described in this paper, can be used to synthesize multilevel signals through the combination of binary data streams. Using this proposed technology, multilevel signals can be coherently synthesized at a high bit rate, and clearer constellations can be obtained. Further, because of its flexibility, and versatility, the EO-DAC can be used for the several types of multilevel modulation formats. In this paper, we describe the EO synthesis of optical multilevel signals especially focusing on the method based on the EO-DAC, along with comparisons with other conventional methods. View full abstract»

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  • Wavelength-Selective Switches for ROADM Applications

    Publication Year: 2010 , Page(s): 1150 - 1157
    Cited by:  Papers (31)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (756 KB) |  | HTML iconHTML  

    The trends, architecture, and performance of wavelength-selective switches (WSS) are analyzed in the context of their application to reconfigurable optical add/drop multiplexer (ROADM)-based optical networks. The resulting analyses define the requirements for the latest generation of ROADM systems and provide insight into the critical specifications of this technology. In addition, the current trends for WSS technology are reviewed in the context of synergies with the strengths of different switching technologies. View full abstract»

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  • Endless Optical Polarization Control at 56 krad/s, Over 50 Gigaradian, and Demultiplex of 112-Gb/s PDM-RZ-DQPSK Signals at 3.5 krad/s

    Publication Year: 2010 , Page(s): 1158 - 1163
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (802 KB) |  | HTML iconHTML  

    In this paper, we present an field-programmable gate array-based automatic endless optical polarization control system, which drives a commercial LiNbO3 polarization transformer. It is capable of tracking endless polarization changes of up to 56 krad/s with mean and maximum polarization errors of 0.077 and 0.197 rad, respectively. While tracking up to 50 krad/s, the system was likewise tested over >2 weeks with maximum polarization error of 0.195 rad during which time it tracked polarization changes of 50 Gigaradian. 112-Gb/s polarization-division multiplexed return to zero differential quadrature phase-shift keying transmission with direct detection and polarization scrambling up to 3.5 krad/s is also demonstrated. View full abstract»

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  • Digital Coherent Optical Receivers: Algorithms and Subsystems

    Publication Year: 2010 , Page(s): 1164 - 1179
    Cited by:  Papers (98)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (760 KB) |  | HTML iconHTML  

    Digital coherent receivers have caused a revolution in the design of optical transmission systems, due to the subsystems and algorithms embedded within such a receiver. After giving a high-level overview of the subsystems, the optical front end, the analog-to-digital converter (ADC) and the digital signal processing (DSP) algorithms, which relax the tolerances on these subsystems are discussed. Attention is then turned to the compensation of transmission impairments, both static and dynamic. The discussion of dynamic-channel equalization, which forms a significant part of the paper, includes a theoretical analysis of the dual-polarization constant modulus algorithm, where the control surfaces several different equalizer algorithms are derived, including the constant modulus, decision-directed, trained, and the radially directed equalizer for both polarization division multiplexed quadriphase shift keyed (PDM-QPSK) and 16 level quadrature amplitude modulation (PDM-16-QAM). Synchronization algorithms employed to recover the timing and carrier phase information are then examined, after which the data may be recovered. The paper concludes with a discussion of the challenges for future coherent optical transmission systems. View full abstract»

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  • Equalizer Design and Complexity for Digital Coherent Receivers

    Publication Year: 2010 , Page(s): 1180 - 1192
    Cited by:  Papers (31)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (830 KB) |  | HTML iconHTML  

    Digital signal processing has completely changed the way optical communication systems work during recent years. In combination with coherent demodulation, it enables compensation of optical distortions that seemed impossible only a few years ago. However, at high bit rates, this comes at the price of complex processing circuits and high power consumption. In order to translate theoretic concepts into economically viable products, careful design of the digital signal processing algorithms is needed. In this paper, we give an overview of digital equalization algorithms for coherent receivers and derive expressions for their complexity. We compare single-carrier and multicarrier approaches, and investigate blind equalizer adaptation as well as training-symbol-based algorithms. We examine tradeoffs between parameters like sampling rate and tracking speed that are important for algorithm design and practical implementation. View full abstract»

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  • Electronic Polarization Control Algorithms for Coherent Optical Transmission

    Publication Year: 2010 , Page(s): 1193 - 1200
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (850 KB) |  | HTML iconHTML  

    In this paper, we review the nondata-aided constant-modulus algorithm (CMA) and a data-aided decision-directed algorithm (DDA) for polarization control and propose different extensions to both algorithms to improve their performance. The first extension to the CMA enables a common carrier recovery (CCR) through differential phase compensation (DPC-CMA). The second extension adapts the CMA for quadrature amplitude modulation signals (CMA-QAM). Both extensions can be combined to form a DPC-CMA for QAM signals (DPC-CMA-QAM). A new, modified DDA (MDDA) considerably increases polarization tracking speeds compared to the original DDA (ODDA). It is also usable for QAM signals. The algorithms are compared in simulations of QPSK and 16-QAM transmission systems. The results show that the DPC extension for the CMA in combination with CCR doubles laser linewidth tolerance and also the CMA-QAM triples polarization control speed compared to the standard CMA for QAM signals. The MDDA is 1.6-4 times faster than the CMA variants and is, at least when QAM signals are transmitted, more hardware-efficient. View full abstract»

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  • Improvements to Digital Carrier Phase Recovery Algorithm for High-Performance Optical Coherent Receivers

    Publication Year: 2010 , Page(s): 1201 - 1209
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (493 KB) |  | HTML iconHTML  

    The Viterbi-and-Viterbi (V-V) algorithm is widely used to recover the carrier phase in optical digital coherent receivers. For simplicity, the basic V-V algorithm assumes constant carrier phase within the average duration. However, this basic assumption is probably violated by factors such as laser frequency offset and nonlinear XPM. In order to improve the basic V-V carrier phase recovery, five methods are introduced, verified, and analyzed. All these methods are compatible with parallel implementation that is mandatory for a realistic DSP circuit. The Q-improvement brought by each algorithm is analyzed together with the complexity of each. Among the five methods, the laser frequency offset compensation expands the tolerable frequency offset to 0.37 symbol rate, and the optimum weighted averaging in conjunction with normalization processing improves the Q-value by 2 dB under severe XPM condition. View full abstract»

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  • Phase-Noise-Tolerant Two-Stage Carrier Recovery Concept for Higher Order QAM Formats

    Publication Year: 2010 , Page(s): 1210 - 1216
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (966 KB) |  | HTML iconHTML  

    In this paper, a phase-noise-tolerant two-stage carrier recovery concept for arbitrary quadrature amplitude modulation (QAM) constellations is presented. Possible implementations are evaluated in simulations of square 16-QAM, 64-QAM, and 256-QAM transmission systems, considering fourth-power and decision-directed carrier recovery for the first stage. The second stage uses QAM feedforward carrier recovery. It is shown that the two-stage concept achieves the same phase noise tolerance as the original QAM feedforward carrier recovery concept, but reduces the required hardware effort by factors of 1.5-3 depending on the order of the QAM constellation. View full abstract»

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  • Mitigation of Fiber Nonlinearity Using a Digital Coherent Receiver

    Publication Year: 2010 , Page(s): 1217 - 1226
    Cited by:  Papers (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (695 KB) |  | HTML iconHTML  

    Coherent detection with receiver-based DSP has recently enabled the mitigation of fiber nonlinear effects. We investigate the performance benefits available from the backpropagation algorithm for polarization division multiplexed quadrature amplitude phase-shift keying (PDM-QPSK) and 16-state quadrature amplitude modulation (PDM-QAM16). The performance of the receiver using a digital backpropagation algorithm with varying nonlinear step size is characterized to determine an upper bound on the suppression of intrachannel nonlinearities in a single-channel system. The results show that for the system under investigation PDM-QPSK and PDM-QAM16 have maximum step sizes for optimal performance of 160 and 80 km, respectively. Whilst the optimal launch power is increased by 2 and 2.5 dB for PDM-QPSK and PDM-QAM16, respectively, the Q-factor is correspondingly increased by 1.6 and 1 dB, highlighting the importance of studying nonlinear compensation for higher level modulation formats. View full abstract»

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  • Real-time implementation of digital signal processing for coherent optical digital communication systems

    Publication Year: 2010 , Page(s): 1227 - 1234
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (253 KB) |  | HTML iconHTML  

    Digital signal-processing-based coherent optical communication systems are widely viewed as the most promising next-generation long-haul transport systems. One of the biggest challenges in building these systems is the implementation of signal processors that are able to deal with signaling rates of a few tens of giga-samples per second. In this paper, we discuss implementation options and design considerations with respect to hardware realization and DSP implementation. View full abstract»

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  • Real-Time Digital Signal Processing for the Generation of Optical Orthogonal Frequency-Division-Multiplexed Signals

    Publication Year: 2010 , Page(s): 1235 - 1244
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (831 KB) |  | HTML iconHTML  

    In this paper, we investigate the design of a field-programmable-gate-array (FPGA) based optical orthogonal frequency-division multiplexing (OFDM) transmitter implementing real-time digital signal processing at 21.4 GSample/s. The transmitter was utilized to generate 8.34 Gb/s QPSK-OFDM signals for direct detection. We study the impact of the finite resolutions of the inverse fast Fourier transform cores and the digital-to-analog converters on the system performance. Furthermore, we describe a transmission experiment over 800 and 1600 km of uncompensated standard fiber with negligible optical SNR penalties and bit error rate <; 10-3. View full abstract»

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  • Future Prospects for FEC in Fiber-Optic Communications

    Publication Year: 2010 , Page(s): 1245 - 1257
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (267 KB) |  | HTML iconHTML  

    This paper reviews the application of forward error correction (FEC) techniques to long-haul fiber-optic communication systems. A brief tutorial on error-correcting codes and a discussion of their fundamental limits (on the additive white Gaussian noise channel and on a nonlinear fiber-optic transmission channel) is provided. To illustrate the potential for applying advanced FEC techniques that take channel nonlinearities into account, a novel faster than Nyquist style binary signaling scheme, providing significant rate improvements over a reference benchmark system, is described. To achieve higher spectral efficiencies, the judicious combination of higher order modulation schemes with FEC is discussed. Finally, several potential directions for further research in the application of advanced FEC systems to nonlinear fiber-optic channels are given. View full abstract»

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  • Soft-Decision-Based Forward Error Correction for 100 Gb/s Transport Systems

    Publication Year: 2010 , Page(s): 1258 - 1267
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (672 KB) |  | HTML iconHTML  

    Soft-decision-based forward error correction (FEC) and its practical implementation for 100 Gb/s transport systems are discussed. In applying soft-decision FEC to a digital coherent transponder, we address the configuration of the frame structure of the FEC. For dual-polarized multilevel modulation formats, the keys are having the FEC frames constructed individually for each polarization and a multilane distribution architecture to align each frame. We present two types of soft-decision FEC. One is the concatenation of a Reed-Solomon code and a low-density parity-check (LDPC) code with 2-bit soft decision yielding a Q limit of 7.5 dB. The other, even more powerful, is a triple-concatenated FEC, with a pair of concatenated hard-decision-based block codes further concatenated with a soft-decision-based LDPC code for 20.5% redundancy. We expect that the proposed triple-concatenated codes can achieve a Q limit of 6.4 dB and a net coding gain of 10.8 dB at a post-FEC bit error ratio of 10-15. For the practical implementation of soft-decision FEC for 100 Gb/s systems, we developed field-programmable gate array boards to emulate it. The concept of hardware emulation, with a scalable architecture for the FEC decoder boards, is introduced by way of a pipelined architecture. View full abstract»

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Aims & Scope

Papers published in the IEEE Journal of Selected Topics in Quantum Electronics fall within the broad field of science and technology of quantum electronics of a device, subsystem, or system-oriented nature.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Luke F. Lester
Virginia Polytechnic Institute & State University