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Lightwave Technology, Journal of

Issue 20 • Date Oct.15, 2012

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Displaying Results 1 - 24 of 24
  • 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): 3183 - 3184
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  • Joint-Polarization and Joint-Subchannel Carrier Phase Estimation for 16-QAM Optical Systems

    Page(s): 3185 - 3191
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1392 KB) |  | HTML iconHTML  

    Carrier phase estimation using information from multiple subchannels and orthogonal polarization channels is proposed and experimentally verified. The concept is evaluated with a 112 Gb/s dual-channel DP-16-QAM system, but may find applications in next generation Terabit systems utilizing superchannels and containing densely packed subchannels originating from the same laser. The new technique requires an accurate carrier frequency estimation algorithm, implemented in the paper using a decision-directed method. The algorithms are tested with a narrow (100 kHz) and a broad (2 MHz) linewidth laser in the coherent receiver. View full abstract»

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  • Performance of Instantaneous Microwave Analysis by Parametric Channelized Receiver Through Time Domain Monitoring

    Page(s): 3192 - 3198
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1026 KB) |  | HTML iconHTML  

    For many applications, ranging from commercial, surveillance, or defense, it is essential to analyze the frequency components of a captured microwave signal over a wide bandwidth in real time and with high resolution. Various photonic approaches have been proposed for the processing of wideband microwave signals in order to overcome limitations imposed by conventional electronic frequency measurements. Here, we present the performance analysis and characterization of a parametric channelized receiver with 275 MHz resolution defined by the Fabry-Perot 3 dB bandwidth and 1 GHz step. Our approach relies on the generation of high quality copies of the RF input by self-seeding wavelength multicasting in a two-pump parametric mixer. Periodic filtering using off-the-shelf elements is then performed on the multicast beam. Ease of filtering is thus achieved by relying on frequency nondegeneracy of the newly generated copies. In this paper, instantaneous analysis of the incoming microwave signal is demonstrated by simultaneous monitoring five of the generated parametric copies while transmitting a frequency-hopping pattern. Operating margins in terms of optical and microwave powers are studied using the five-channel data simultaneously collected on a real-time oscilloscope. Dynamic range adjustments through optical power tuning of the input signal seed are demonstrated. Finally, the effects of frequency mapping detuning are observed to determine optimal operating conditions. View full abstract»

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  • A Novel Method for Stripping Cladding Lights in High Power Fiber Lasers and Amplifiers

    Page(s): 3199 - 3202
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (903 KB) |  | HTML iconHTML  

    Fabrication techniques for the manufacture of a high power cladding light stripper are presented. Localized heating and thermal degradation of the recoating materials are the prime limiting factors for the operation of a high power cladding light stripper. In order to overcome this difficulty, the fiber is tapered by hydrofluoric (HF) acid and the surface of the tapered region is exposed to HF acid vapor. The acid vapor creates fine holes and scratches on the fiber surface. A low refractive index polymer is then used to recoat the fiber surface, which extracts the unwanted cladding light from the fiber over a relatively large area. This eliminates the abrupt removal of light and consequently the detrimental thermal effects due to localized heating. The power-handling capability of the device is tested under 90 W of cladding light, and attenuation of 16.7 dB is achieved. View full abstract»

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  • Improving the Power Efficiency in End-Pumped Gain-Guided Index-Antiguided Fiber Amplifiers

    Page(s): 3203 - 3210
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    In this paper, we highlight the key reasons behind the poor power efficiency observed in multiple experiments in gain-guided index-antiguided (GG-IAG) fiber amplifiers and lasers. We show that by properly designing the fiber geometrical characteristics, it is possible to considerably improve the power efficiency of GG-IAG fiber amplifiers in end-pumping schemes. View full abstract»

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  • Ring-Based WDM Access Network Providing Both Rayleigh Backscattering Noise Mitigation and Fiber-Fault Protection

    Page(s): 3211 - 3218
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1485 KB) |  | HTML iconHTML  

    In this paper, we propose and investigate a ring-based wavelength-division-multiplexing passive optical network (WDM-PON) providing both Rayleigh backscattering (RB) noise mitigation and fiber-fault protection. The proposed ring-based WDM-PON has a dual-ring architecture to protect and restore any fiber fault. Besides, the ring architecture also can mitigate the RB beat noise, since the RB and the upstream wavelengths are propagating in opposite directions. Here, we discuss and analyze the characteristics of the downstream signals using 10 Gb/s ON-OFF keying (OOK), 10 Gb/s differential phase-shift keying, and 10 Gb/s orthogonal frequency-division multiplexing (OFDM) modulations, respectively. Moreover, we also investigate the upstream traffic using the 2.5 Gb/s OOK and 10 Gb/s OFDM generated by the directly modulated reflective semiconductor optical amplifier-based optical network unit, respectively. View full abstract»

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  • Analysis of Noise Spread in Optical DFT-S OFDM Systems

    Page(s): 3219 - 3225
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1298 KB) |  | HTML iconHTML  

    A discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S OFDM) scheme is attractive for its effective peak-to-average power ratio (PAPR) reduction. This paper presents another important issue about DFT-S OFDM, which is noise spread induced by the extra inverse discrete Fourier transform for DFT-S OFDM data recovery at the receiver. It would reduce the optical signal-to-noise ratio (OSNR) and spread the noise over the whole DFT-S OFDM subband, make DFT-S OFDM being more sensitive to noise distribution, and weaken the improvement induced by PAPR reduction. The principle of DFT-S OFDM generation and theoretical analysis of the noise spread in DFT-S OFDM signal processing at the receiver is presented. 100 Gb/s multiband DFT-S OFDM simulation system and 2.5 Gb/s experiment have been demonstrated to prove that the DFT-S OFDM scheme has worse performance than the conventional OFDM scheme under the condition of low OSNR and bad channel estimation; hence, it is more sensitive to the OSNR in transmission channel and needs more accurate channel estimation. View full abstract»

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  • A Real-Time QKD System Based on FPGA

    Page(s): 3226 - 3234
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1171 KB) |  | HTML iconHTML  

    A real-time quantum key distribution (QKD) system is developed in this paper. In the system, based on the feature of a field-programmable gate array, secure key extraction control and algorithm have been optimally designed to perform sifting, error correction, and privacy amplification altogether in real time. In the QKD experiment, information synchronization mechanism and high-speed classic data channel are designed to ensure the steady operation of the system. Decoy state and synchronous laser light source are used in the system, while the length of optical fiber between Alice and Bob is 20 km. With photons repetition frequency of 20 MHz, the final key rate could reach 17 kb/s. Smooth and robust operation is verified with 6 h continuous test and associated with encrypted voice communication test. View full abstract»

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  • Theoretical Modeling of Ho-Doped Fiber Lasers Pumped by Laser-Diodes Around 1.125 \mu m

    Page(s): 3235 - 3240
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (975 KB) |  | HTML iconHTML  

    A theoretical model to describe Holmium-doped fiber lasers pumped by Laser-diodes around 1.125 μm is presented. With considerations of important energy transfer processes, such as laser re-absorption, cross-relaxation (CR), energy transfer upconversion (ETU), and excited state absorption (ESA), good agreement is achieved between the simulations and experimental measurements. The ESA process is found playing an important role to the fiber laser performance, and the CR and ETU processes make a negative contribution to the lasers. On the basis of the model, optimization of the lasers threshold and slope efficiency as well as output power on the length of active media, the output coupling, pump wavelength, and Ho3+ ions concentration are investigated. It is found that lower doping concentration (about 5000 ~ 10000 ppm) for the fiber lasers is preferred for efficient operation. View full abstract»

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  • GaN-Based LEDs With Contact-Transferred and Mask-Embedded Lithography and In-Situ N _{2} Treatments

    Page(s): 3241 - 3246
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (895 KB) |  | HTML iconHTML  

    The authors report that GaN-based LEDs with contact-transferred and mask-embedded lithography (CMEL) and in-situ N treatments were fabricated. From the experiment results, it can be seen clearly that the characteristic of ITO contacts on the etched p-GaN with the N treatment-20 sccm shows a near ohmic behavior. With 20 mA current injection, it was found that forward voltage and output power were 3.09 V and 5.16 mW for the LED with CMEL-400 nm-treatment. It was also found that we can achieve 20.5% enhancement for the LED with CMEL-400 nm and do not degrade the electrical properties of the GaN-based LEDs. Furthermore, the reliability of the proposed LED was good. View full abstract»

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  • An Integrated Long-Reach PON and GI-POF In-House Network Architecture for Hybrid CATV/OFDM Signals Transmission

    Page(s): 3247 - 3251
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (915 KB) |  | HTML iconHTML  

    We propose and demonstrate an integrated long- reach passive optical network (PON) and in-house graded-index plastic optical fiber (GI-POF) network architecture for hybrid community antenna television (CATV) and orthogonal frequency division multiplexing (OFDM) signals transmission. By reasonably multiplexing the OFDM and CATV signals into a CATV transmitter, both signals originated from a central office (CO) are successfully transmitted over a span of 60 km single mode fiber (SMF) and another span of 25 m GI-POF to consumers' devices. Although the SMF and GI-POF have different core sizes and attenuation features, no any bridge circuit or wavelength converter is utilized in the proposed architecture resulting in a transparent platform for the Internet service providers (ISPs) to directly manage their long-distance services toward suburban or rural areas. Since the optical signal generated at the CO can be transmitted straightforward to the consumers' devices, the average packet delay and packet overhead size can be greatly reduced and the quality of services (QoS) can be maintained easier. Good experimental performances of the CATV and OFDM signals transmission proof the practice and efficiency of this proposal to extend multimedia services from metro areas to suburban and rural areas. View full abstract»

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  • Nanoscale Resolution Interrogation Scheme for Simultaneous Static and Dynamic Fiber Bragg Grating Strain Sensing

    Page(s): 3252 - 3258
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1009 KB) |  | HTML iconHTML  

    A combined interrogation and signal processing technique which facilitates high-speed simultaneous static and dynamic strain demodulation of multiplexed fiber Bragg grating sensors is described. The scheme integrates passive, interferometric wavelength-demodulation and fast optical switching between wavelength division multiplexer channels with signal extraction via a software lock-in amplifier and fast Fourier transform. Static and dynamic strain measurements with noise floors of 1 nε and nε/√Hz, between 5 mHz and 2 kHz were obtained. An inverse analysis applied to a cantilever beam set up was used to characterize and verify strain measurements using finite element modeling. By providing distributed measurements of both ultra-high-resolution static and dynamic strain, the proposed scheme will facilitate advanced structural health monitoring. View full abstract»

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  • Graphene Oxide Absorbers for Watt-Level High-Power Passive Mode-Locked Nd:GdVO _{4} Laser Operating at 1 \mu m

    Page(s): 3259 - 3262
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (930 KB) |  | HTML iconHTML  

    A novel graphene-oxide-based saturable absorber with 12% modulation depth, which is fabricated by the novel vertical evaporation technique, can be used to passively mode locked the Nd:GdVO4 ultrafast laser system. The maximum average output power measured is 1.1 W and it is operating at TEM00 mode. The measured pulse duration and repetition rate are 4.5 ps and 70 MHz, respectively. This low-cost, broadband graphene-oxide-based saturable absorber can potentially be used practically in the high-power mode-locking laser system. View full abstract»

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  • New Design of a Thulium–Aluminum-Doped Fiber Amplifier Based on Macro-Bending Approach

    Page(s): 3263 - 3272
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    A new method for gain enhancement in a S-band thulium-doped fiber amplifier (TDFA) co-doped with aluminum is demonstrated using a macro-bending approach. The macrobending of the doped fiber in a small radius suppresses both amplified spontaneous emissions (ASEs) at 800 and 1800 nm band and thus increases the population inversion in the S-band region. The numerical aperture and core radius of the doped fiber are optimized so that 800 nm ASE propagates with higher order modes to achieve a significant suppression while the loss is minimum in the S-band region. Meanwhile, the 1050 nm pump wavelength should propagate in the fundamental mode to maximize the overlap factor and thulium ion absorption so that the ASE loss is maximum at the 1800 nm region. Gain enhancements of about 5-8 dB are obtained with macrobending at the wavelength region between 1420 and 1470 nm. View full abstract»

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  • Performance and Power Dissipation Comparisons Between 28 Gb/s NRZ, PAM, CAP and Optical OFDM Systems for Data Communication Applications

    Page(s): 3273 - 3280
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (876 KB) |  | HTML iconHTML  

    Theoretical investigations have been carried out to analyze and compare the link power budget and power dissipation of non-return-to-zero (NRZ), pulse amplitude modulation-4 (PAM-4), carrierless amplitude and phase modulation-16 (CAP-16) and 16-quadrature amplitude modulation-orthogonal frequency division multiplexing (16-QAM-OFDM) systems for data center interconnect scenarios. It is shown that for multimode fiber (MMF) links, NRZ modulation schemes with electronic equalization offer the best link power budget margins with the least power dissipation for short transmission distances up to 200 m; while OOFDM is the only scheme which can support a distance of 300 m albeit with power dissipation as high as 4 times that of NRZ. For short single mode fiber (SMF) links, all the modulation schemes offer similar link power budget margins for fiber lengths up to 15 km, but NRZ and PAM-4 are preferable due to their system simplicity and low power consumption. For lengths of up to 30 km, CAP-16 and OOFDM are required although the schemes consume 2 and 4 times as much power respectively compared to that of NRZ. OOFDM alone allows link operation up to 35 km distances. View full abstract»

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  • Silicon Polarization Beam Splitter Based on an Asymmetrical Evanescent Coupling System With Three Optical Waveguides

    Page(s): 3281 - 3287
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    A short polarization beam splitter (PBS) is presented based on an asymmetrical evanescent coupling system, which consists of a narrow input waveguide, a narrow output waveguide, and a wide middle optical waveguide between them. The width of the waveguides is designed so that the phase-matching condition is satisfied for the TM fundamental (TM0) mode in the narrow input/output waveguide and the first higher order TM (TM1) mode in the wide middle waveguide. Meanwhile, there is a significant phase mismatch for the case with TE polarization. Therefore, for the launched TE polarized light, almost no coupling happens when it goes through the coupling region and finally the TE polarized light is output from the through port. For the launched TM0 mode in the narrow input waveguide, it is completely coupled to the TM1 mode in the wide middle waveguide by choosing the optimal length of the coupling region. Furthermore, the TM1 mode excited in the wide middle waveguide is then coupled to the TM0 mode in the narrow output waveguide through the evanescent coupling between them. A short (~25 μm long) PBS is designed based on silicon-on-insulator nanowires, while the gap width is chosen as large as 300 nm to make the fabrication easy. Numerical simulations show that the present PBS has a good fabrication tolerance for the variation of the waveguide width (more than ± 20 nm) and a broadband ( ~ 50 nm) for an extinction ratio of >; 15 dB. View full abstract»

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  • Design of Multicavities on Left-Handed Photonic-Crystal-Based Chemical Sensors

    Page(s): 3288 - 3293
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (814 KB) |  | HTML iconHTML  

    This paper presents a theoretical study on a novel chemical sensor platform based on a 2-D photonic crystal with negative refraction (PCNR). The proposed device consists of distributed multinanocavities embedded within the PCNR. A 2-D finite-difference time-domain method with perfectly matched layers has been employed to investigate the performance of the sensor for different analytes and structural parameters. The calculations show that it is possible to detect simultaneously two analytes when the refractive index is larger than that of water. The quality factor was determined to be around 105 when the radii of the central nanocavity is and that of the external is . View full abstract»

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  • Open Access

    Page(s): 3294
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    Freely Available from IEEE
  • IEEE Xplore Digital Library

    Page(s): 3295
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    Freely Available from IEEE
  • IEEE Foundation

    Page(s): 3296
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    Freely Available from IEEE
  • Journal of Lightwave Technology information for authors

    Page(s): C3
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  • [Blank page - back cover]

    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