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| 2. |
- Alic, N., et al.
(författare)
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Benefits of Joint Statistics in MLSD-Equalized Transmission
- 2009
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Ingår i: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 21:8, s. 495-497
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Tidskriftsartikel (refereegranskat)abstract
- We experimentally investigate and quantify performance improvement, accounting for multiple bit intervals' joint statistics in filtered equalized on-off keying OC-192 fiber-optic links relying on Viterbi-algorithm-based sequence detection. We demonstrate that the penalty associated with narrow filtering can be alleviated for the most part with an appropriate detection approach.
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| 3. |
- Alic, N., et al.
(författare)
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Joint Statistics and MLSD in Filtered Incoherent High-Speed Fiber-Optic Communications
- 2010
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 28:10, s. 1564-1572
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, signal statistics and their utilization for detection in narrowly filtered equalized high-speed fiber-optic communications are investigated experimentally. Tradeoffs between log-likelihood metric applications and oversampling are covered in detail. It is, for the first time, demonstrated that performance loss in bandwidth-limited systems can be nearly fully recovered (to within 0.5 dB) by taking advantage of band-width-limitation-induced noise correlations and oversampling.
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| 4. |
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| 5. |
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| 6. |
- Gonzalez-Mirelis, Genoveva, 1977, et al.
(författare)
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Using Vessel Monitoring System Data to Improve Systematic Conservation Planning of a Multiple-Use Marine Protected Area, the Kosterhavet National Park (Sweden)
- 2014
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 43:2, s. 162-174
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Tidskriftsartikel (refereegranskat)abstract
- When spatial fishing data is fed into systematic conservation planning processes the cost to a fishery could be ensured to be minimal in the zoning of marine protected areas. We used vessel monitoring system (VMS) data to map the distribution of prawn trawling and calculate fish- ing intensity for 1-ha grid cells, in the Kosterhavet National Park (Sweden). We then used the software Marxan to generate cost-efficient reserve networks that represented every biotope in the Park. We asked what were the potential gains and losses in terms of fishing effort and species conservation of different planning scenarios. Given a conservation target of 10 % representation of each bio- tope, the fishery need not lose more than 20 % of its fishing grounds to give way to cost-efficient conservation of ben- thic diversity. No additional reserved area was needed to achieve conservation targets while minimizing fishing costs. We discuss the benefits of using VMS data for conservation planning.
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| 7. |
- Lu, Guo-Wei, 1976, et al.
(författare)
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40-Gbaud 16-QAM transmitter using tandem IQ modulators with binary driving electronic signals
- 2010
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Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 18:22, s. 23062-23069
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Tidskriftsartikel (refereegranskat)abstract
- We propose a novel 16-quadrature amplitude modulation (QAM) transmitter based on two cascaded IQ modulators driven by four separate binary electrical signals. The proposed 16-QAM transmitter features scalable configuration and stable performance with simple bias-control. Generation of 16-QAM signals at 40 Gbaud is experimentally demonstrated for the first time and visualized with a high speed constellation analyzer. The proposed modulator is also compared to two other schemes. We investigate the modulator bandwidth requirements and tolerance to accumulated chromatic dispersion through numerical simulations, and the minimum theoretical insertion attenuation is calculated analytically.
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| 8. |
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| 9. |
- Sjödin, Martin E, 1983, et al.
(författare)
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Cancellation of SPM in Self-Homodyne Coherent Systems
- 2009
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Ingår i: Proceedings of European Conference on Optical Communication, ECOC 2009, Vienna, Austria, September 20-24, 2009, paper We8.4.5.
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Konferensbidrag (refereegranskat)abstract
- The signal and local oscillator acquire identical nonlinear phase shifts during propagation in a selfhomodynecoherent system. We exploit this to achieve cancellation of the phase distortion caused by self-phasemodulation.
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| 10. |
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| 11. |
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| 12. |
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| 13. |
- Sköld, Mats, 1977, et al.
(författare)
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Constellation diagram measurements of induced phase noise in a regenerating parametric amplifier
- 2008
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Ingår i: OFC/NFOEC 2008 - 2008 Conference on Optical Fiber Communication/National Fiber Optic Engineers Conference; San Diego, CA; United States; 24 February 2008 through 28 February 2008. - 9781557528551 ; , s. OML4-
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Konferensbidrag (refereegranskat)abstract
- We perform coherent constellation diagram measurements of phase modulated data before and after a saturated parametric amplifier, and find a novel kind of pump-induced phase noise in the amplifier.
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| 14. |
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| 15. |
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| 17. |
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| 18. |
- Sköld, Mats, 1977, et al.
(författare)
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Polarization-based Monitoring in WDM Systems
- 2007
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Ingår i: Proceedings of Optoelectronics and Communications Conference. - 9784885522215 ; , s. 346-347
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 19. |
- Sköld, Mats, 1977, et al.
(författare)
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Quasi-Real-Time Optical Sampling Scheme for High-Speed Signal Acquisition and Processing
- 2013
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Ingår i: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 25:5, s. 504-507
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Tidskriftsartikel (refereegranskat)abstract
- We present a quasi-real-time coherent sampling approach that combines the high-bandwidth and high-fidelity signal acquisition of equivalent-time optical sampling with real-time digital signal processing and equalization algorithms. The quasi-real-time concept enables feasibility studies of optical communication at symbol rates beyond the bandwidth of conventional digitizer approaches. Here we demonstrate the technique using a 107-GBd polarization-division-multiplexed quadrature phase shift keyed signal.
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| 20. |
- Sköld, Mats, 1977
(författare)
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Signal Characterization in Optical Networks
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The thesis presents and demonstrates methods to characterize high-speed (>10 Gbaud) signals in fiber optic communication systems and networks, including acquisition of the optical signal intensity, amplitude, phase and polarization. These quantities are necessary for the analysis of system performance, both in research and development stages, as well as for monitoring and management of operational systems. This becomes increasingly important as the optical communications systems develop toward using more sophisticated modulation formats.We demonstrated real-time optical intensity waveform sampling with high sampling rate and simultaneous high bandwidth by parallelizing the sampling in four optical gates. The optical sampling gates provide a total sampling rate of 100 GSample/s with sampling bandwidth limited by the Nyquist criterion. As an example, the first real-time acquisition of a 40 GHz bandwidth signal was demonstrated.The characterization of the full optical field, i.e. both the optical signal amplitude and phase, was used to analyze the regenerative properties of a saturated parametric amplifier on a 10 Gbit/s differential phase shift keying (DPSK) signal. The optical signal was visualized in a constellation diagram which enabled separation of amplitude and phase fluctuations.By introducing the phase preserving optical sampling gate to our coherent detection scheme, we were able to increase the temporal resolution tenfold. The high bandwidth was demonstrated by studying a 40 Gbit/s DPSK signal. Furthermore, we visualized the signal transitions by implementing signal averaging.Polarization analysis was utilized to characterize system properties. We investigated the polarization-mode dispersion (PMD) properties of a recirculation loop. It was found that, in contrast to the normal Maxwellian distribution, the first-order PMD statistics approaches a uniform distribution when no loop-synchronous polarization scrambling is used. Furthermore, we demonstrated methods to utilize the signal polarization for low-cost optical performance monitoring. The methods provide information about several parameters, e.g. power, wavelength, optical signal-to-noise ratio (OSNR), first-order PMD, etc., and the practical feasibility was demonstrated in an 820 km long installed optical system.
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| 21. |
- Sunnerud, Henrik, 1971, et al.
(författare)
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All-Optical Balanced Detection System with sub-ps Resolution
- 2009
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Ingår i: 2009 Conference on Optical Fiber Communication, OFC 2009; San Diego, CA; United States; 22 March 2009 through 26 March 2009. - Washington, D.C. : OSA. - 9781557528650 ; , s. Art. no. 5032648-
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Konferensbidrag (refereegranskat)abstract
- We demonstrate a dual-channel all-optical sampling system that simultaneously samples the two output ports from a DPSK demodulator. The two channels are combined to perform balanced detection with sub-ps resolution.
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| 22. |
- Tipsuwannakul, Ekawit, 1982, et al.
(författare)
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Comparison of 112-Gb/s PM-RZ-DQPSK and PM-RZ-D8PSK in Terms of OSNR Requirement and Transmission Impairments
- 2009
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Ingår i: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 21:22, s. 1680 - 1682
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Tidskriftsartikel (refereegranskat)abstract
- We have, for the first time, experimentally investigated112-Gb/s polarization-multiplexed return-to-zero differential8-ary phase-shift keying (PM-RZ-D8PSK) with differentialdetection in terms of optical signal-to-noise ratio requirement,group velocity dispersion (GVD), and differential group delay(DGD) tolerances, together with a direct comparison with PM-RZdifferential quadrature phase-shift keying at equivalent bit rate.The results indicate higher tolerances with respect to GVD andDGD but lower receiver sensitivity in the case of PM-RZ-D8PSK
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| 23. |
- Tipsuwannakul, Ekawit, 1982, et al.
(författare)
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Performance Comparison of Differential 8-Ary Modulation Formats in High-Speed Optical Transmission Systems
- 2011
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 29:19, s. 2954-2962
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents back-to-back and transmission performance comparisons between single-polarization 120 Gbit/s RZ-DQP-ASK and RZ-D8PSK formats in a single-wavelength system. In the back-to-back configuration, we determine the OSNR requirements of the two formats and compare the results with those obtained analytically and numerically. In the transmission experiments, we examine signal constellations to quantify the significance of intra-channel fiber nonlinearities and investigate the BER performance of the two formats over different reaches (up to 480 km). The results show that the performance of DQP-ASK is superior to D8PSK in back-to-back configuration but is inferior over long distances.
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| 24. |
- Tipsuwannakul, Ekawit, 1982, et al.
(författare)
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Transmission of 240 Gb/s PM-RZ-D8PSK over 320 km in 10 Gb/s NRZ-OOK WDM System
- 2010
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Ingår i: Optical Fiber Communication Conference, OFC 2010; San Diego, CA; United States; 21 March 2010 through 25 March 2010. - 2162-2701. - 9781557528841
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Konferensbidrag (refereegranskat)abstract
- We present the first demonstration of 40 Gbaud PM-RZ-D8PSK and its successful transmission in a 100 GHz-spaced 10 Gb/s NRZ-OOK WDM system over a 320-km transmission link along with the studies of WDM nonlinear crosstalk.
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| 25. |
- Westbergh, Petter, 1981, et al.
(författare)
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High speed, low current density 850 nm VCSELs
- 2009
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Ingår i: IEEE Journal of Selected Topics in Quantum Electronics. - 1558-4542 .- 1077-260X. ; 15:3, s. 694-703
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Tidskriftsartikel (refereegranskat)abstract
- We report on the design, fabrication, and evaluation of large-aperture, oxide-confined 850 nm vertical cavity surface emitting lasers (VCSELs) with high modulation bandwidth at low current densities. We also compare the use of InGaAs and GaAs quantum wells (QWs) in the active region. Both VCSELs reach an output power of 9 mW at room temperature, with a thermal resistance of 1.9deg C/mW. The use of InGaAs QWs improves the high-speed performance and enables a small-signal modulation bandwidth of 20 GHz at 25degC and 15 GHz at 85degC. At a constant bias current density of only 11 kA/cm2, we generate open eyes under large-signal modulation at bit rates up to 25 Gbit/s at 85degC and 30 Gbit/s at 55degC.
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| 26. |
- Westlund, Mathias, 1975, et al.
(författare)
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All-optical phase-sensitive waveform sampling at 40 GSymbol/s
- 2008
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Ingår i: National Fiber Optic Engineers Conference, NFOEC 2008; San Diego, CA; United States; 24 February 2008 through 28 February 2008. - 2162-2701. - 9781557528582 ; , s. PDP12-
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Konferensbidrag (refereegranskat)abstract
- We demonstrate a novel, high-resolution all-optical phase-sensitive sampling method using separate lasers for signal, sampling and mixing. A 40 GBaud DPSK signal was asynchronously sampled and visualized as a constellation diagram including transitions (625 ksamples).
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| 27. |
- Wuth, Torsten, 1971, et al.
(författare)
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Fiber communications using convolutional coding and bandwidth-efficient modulation
- 2006
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Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 14:2, s. 542-555
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we evaluate numerically the advantage of combining convolutional coding and bandwidth-efficient modulation. We compare different multilevel modulation formats, line codes, and hard/soft decision decoding. Compared with DPSK modulation (with the same bandwidth and information transmission rate), an improvement of almost 5 dB is observed for bit error rates around 10 -8 . We also study the robustness to intersymbol interference in the form of chromatic dispersion, and find that the improvement of the coded transmission lines improves over the uncoded even in presence of chromatic dispersion. © 2006 Optical Society of America.
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