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| 2. |
- Agrell, Erik, 1965, et al.
(författare)
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Power-efficient modulation formats in coherent transmission systems
- 2009
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 27:22, s. 5115-5126
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Tidskriftsartikel (refereegranskat)abstract
- Coherent optical transmission systems have a four-dimensional (4-D) signal space (two quadratures in two polarizations). These four dimensions can be used to create modulation formats that have a better power efficiency (higher sensitivity) than the conventional binary phase shift keying/quadrature phase shift keying (BPSK/QPSK) signals. Several examples are given, with some emphasis on a 24-level format and an 8-level format, including descriptions of how they can be realized and expressions for their symbol and bit error probabilities. These formats are, respectively, an extension and a subset of the commonly used 16-level dual-polarization QPSK format. Sphere packing simulations in 2, 3, and 4 dimensions, up to 32 levels, are used to verify their optimality. The numerical results, as the number of levels increases, are shown to agree with lattice-theoretical results. Finally, we point out that the use of these constellations will lead to improved fundamental sensitivity limits for optical communication systems, and they may also be relevant as a way of reducing power demands and/or nonlinear influence. © 2009, IEEE. All rights reserved.
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| 3. |
- 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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| 4. |
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| 5. |
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| 6. |
- Johannisson, Pontus, 1976, et al.
(författare)
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Suppression of Phase Error in Differential Phase-Shift Keying Data by Amplitude Regeneration
- 2006
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Ingår i: Optics Letters. ; 31:10, s. 1385-1387
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Tidskriftsartikel (refereegranskat)abstract
- A regenerator for DPSK modulated data, consisting of two Mach-Zehnder interferometers and two amplitude regenerators, is examined theoretically. The result, which shows that the phase error is suppressed if phase-preserving amplitude regenerators are used, provides a theoretical description of an already experimentally implemented regenerator.
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| 7. |
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| 8. |
- Karlsson, Magnus, 1967, et al.
(författare)
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Effect of nonlinearities on PMD system degradations
- 2006
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Ingår i: OFC/NFOEC 2006. 2006 Optical Fiber Communication Conference and National Fiber Optic Engineers Conference. ; , s. OWE4-
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Konferensbidrag (refereegranskat)abstract
- We review and discuss cross-phase modulation-induced polarization state changes in WDM systems, so called cross-polarization modulation, XPolM, and how it influences outage probabilities in polarization mode dispersion-limited systems
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| 9. |
- Karlsson, Magnus, 1967, et al.
(författare)
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Effects of Nonlinearities on PMD-Induced System Impairments
- 2006
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 24:11, s. 4127-4137
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Tidskriftsartikel (refereegranskat)abstract
- It is well known that cross-phase-modulation-induced polarization rotation, cross-polarization modulation (XPolM), significantly degrades the performance of polarization-mode-dispersion (PMD) compensators. In this paper, the research on XPolM is reviewed, unique simulations of XPolM in the presence of walk off are presented, and some pitfalls are demonstrated with respect to choice of data streams in such simulations. Then, the authors discuss how XPolM affects PMD and PMD-induced outage probabilities (OP) in fiber-communication systems by providing analytical formulas for the OP with and without XPolM. Finally, the XPolM and PMD compensation are tied together by giving simple rules of thumb for when XPolM degrades PMD compensated systems, and PMD mitigation methods that are robust to XPolM are discussed.
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| 10. |
- Karlsson, Magnus, 1967
(författare)
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Fiber optic parametric amplifiers - properties, applications and challenges
- 2008
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Ingår i: Conference on Quantum Electronics and Laser Science Conference on Lasers and Electro-Optics, CLEO/QELS 2008; San Jose, CA; United States; 4 May 2008 through 9 May 2008. - 9781557528599 ; , s. CWJ1-
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Konferensbidrag (refereegranskat)abstract
- This tutorial reviews the basic properties, applications and challenges for fiber-based parametric amplifiers.
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