| 1. |
- Agrell, Erik, 1965, et al.
(författare)
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Roadmap of optical communications
- 2016
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Ingår i: Journal of Optics. - : IOP Publishing. - 2040-8978 .- 2040-8986. ; 18:6
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Tidskriftsartikel (refereegranskat)abstract
- Lightwave communications is a necessity for the information age. Optical links provide enormous bandwidth, and the optical fiber is the only medium that can meet the modern society's needs for transporting massive amounts of data over long distances. Applications range from global high-capacity networks, which constitute the backbone of the internet, to the massively parallel interconnects that provide data connectivity inside datacenters and supercomputers. Optical communications is a diverse and rapidly changing field, where experts in photonics, communications, electronics, and signal processing work side by side to meet the ever-increasing demands for higher capacity, lower cost, and lower energy consumption, while adapting the system design to novel services and technologies. Due to the interdisciplinary nature of this rich research field, Journal of Optics has invited 16 researchers, each a world-leading expert in their respective subfields, to contribute a section to this invited review article, summarizing their views on state-of-the-art and future developments in optical communications.
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| 2. |
- Bjork, G., et al.
(författare)
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Proposed Implementation of "Non-Physical" Four-Dimensional Polarization Rotations
- 2016
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Ingår i: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8724 .- 1558-2213. ; 34:14, s. 3317-3322
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Tidskriftsartikel (refereegranskat)abstract
- Recently one of us proposed a new formalism for modeling electromagnetic wave transformations for coherent communication using a real, four-vector description instead of the conventionally used Jones calculus or the Mueller matrices. The four-vector can then handle all superpositions of two orthogonal polarization basis and two orthogonal time bases (e.g., the in-phase and quadrature phase). In developing this formulation it was found that to provide a general but minimal framework for such rotations, it is natural to divide the six generators of four-dimensional (4d) rotations into two groups of three generators, the right-and the left-isoclinic matrices. Of the six transformations these generators define, it was furthermore found that four of them are readily implemented by linear optical components, while two of then were impossible to implement by such means. In this paper, we detail the reason these two "unphysical" rotations cannot be implemented with linear optics. We also suggest how they can be implemented, but at a cost in the signal-to-noise ratio, and give this minimum cost.
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| 3. |
- Czegledi, Cristian Bogdan, 1988, et al.
(författare)
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Modulation Format Independent Joint Polarization and Phase Tracking for Coherent Receivers
- 2016
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 13:14, s. 3354-3364
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Tidskriftsartikel (refereegranskat)abstract
- © 1983-2012 IEEE. The state of polarization and the carrier phase drift dynamically during transmission in a random fashion in coherent optical fiber communications. The typical digital signal processing solution to mitigate these impairments consists of two separate blocks that track each phenomenon independently. Such algorithms have been developed without taking into account mathematical models describing the impairments. We study a blind, model-based tracking algorithm to compensate for these impairments. The algorithm dynamically recovers the carrier phase and state of polarization jointly for an arbitrary modulation format. Simulation results show the effectiveness of the proposed algorithm, having a fast convergence rate and an excellent tolerance to phase noise and dynamic drift of the polarization at low complexity, which make the algorithm a strong candidate for future optical systems.
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| 4. |
- Czegledi, Cristian Bogdan, 1988, et al.
(författare)
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Polarization Drift Channel Model for Coherent Fibre-Optic Systems
- 2016
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 6, s. 21217-
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Tidskriftsartikel (refereegranskat)abstract
- A theoretical framework is introduced to model the dynamical changes of the state of polarization during transmission in coherent fibre-optic systems. The model generalizes the one-dimensional phase noise random walk to higher dimensions, accounting for random polarization drifts, emulating a random walk on the Poincare sphere, which has been successfully verified using experimental data. The model is described in the Jones, Stokes and real four-dimensional formalisms, and the mapping between them is derived. Such a model will be increasingly important in simulating and optimizing future systems, where polarization-multiplexed transmission and sophisticated digital signal processing will be natural parts. The proposed polarization drift model is the first of its kind as prior work either models polarization drift as a deterministic process or focuses on polarization-mode dispersion in systems where the state of polarization does not affect the receiver performance. We expect the model to be useful in a wide-range of photonics applications where stochastic polarization fluctuation is an issue.
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| 5. |
- Czegledi, Cristian Bogdan, 1988, et al.
(författare)
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Polarization-Mode Dispersion Aware Digital Backpropagation
- 2016
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Ingår i: 42nd European Conference on Optical Communication, ECOC 2016; Dusseldorf; Germany; 18 September 2016 through 22 September 2016. - 9783800742745 ; , s. 1091-1093
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Konferensbidrag (refereegranskat)abstract
- We study a modified DBP algorithm that accounts for PMD. Based on the accumulated PMD at the receiver, the algorithm distributively compensates for PMD in the reverse propagation and outperforms the conventional approach by up to 2.1 dB.
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| 6. |
- Dharmaweera, Madushanka Nishan, 1986, et al.
(författare)
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Nonlinear-Impairments- and Crosstalk-Aware Resource Allocation Schemes for Multicore-Fiber-based Flexgrid Networks
- 2016
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Ingår i: ECOC 2016; 42nd European Conference on Optical Communication; Proceedings of. - 9783800742745
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Konferensbidrag (refereegranskat)abstract
- Abstract: In this study, we propose a novel spectrum and core allocation scheme that incorporates both intra-core physical layer impairments and inter-core crosstalk. We demonstrate that accounting for the latter increases spectral efficiency by at least 50% when crosstalk is significant.
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| 7. |
- Dharmaweera, Madushanka Nishan, 1986, et al.
(författare)
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Regenerator site selection in impairment-aware elastic optical networks
- 2016
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Ingår i: 2016 Optical Fiber Communications Conference and Exhibition (OFC). Anaheim, CA, MAR 20-24, 2016. - 9781943580071
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Konferensbidrag (refereegranskat)abstract
- We propose a novel regenerator site selection scheme for nonlinear impairment-aware elastic optical networks. The proposed scheme reduces bandwidth use by up to 40% in a realistic network by employing only 6 regenerator sites.
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| 8. |
- Dharmaweera, Madushanka Nishan, 1986, et al.
(författare)
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Traffic-grooming- and multipath-routing-enabled impairment-aware elastic optical networks
- 2016
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Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 8:2, s. 58-70
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Tidskriftsartikel (refereegranskat)abstract
- Traffic grooming and multipath routing are two techniques that are widely adopted to increase the performance of traditional wavelength division multiplexed networks. They have been recently applied in elastic optical networks to increase spectral efficiency. In this study, we investigate the potential gains by jointly employing the two techniques in combination with a realistic physical impairment model. To allocate resources and quantify spectral efficiency gains over existing impairment-aware schemes, we present an analytical optimization formulation for small networks and a heuristic for large networks. Through numerical simulations, we demonstrate that traffic grooming and multipath routing, together, increase spectral efficiency and reduce resource consumption over existing schemes. We show that the proposed scheme offers significant performance improvements in networks with low degrees of connectivity, high traffic loads, and long links.
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| 9. |
- Ebenhag, Sven-Christian, et al.
(författare)
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Coherent optical two-way frequency transfer in a commercial DWDM network
- 2016
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Ingår i: Proceedings of the Annual Precise Time and Time Interval Systems and Applications Meeting. - : Institute of Navigation. ; , s. 116-120, s. 116-120
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Konferensbidrag (refereegranskat)abstract
- An experimental fiber connection for ultra-stable optical frequency transfer is established between SP Technical Research Institute of Sweden in Borås and Chalmers University of Technology in Gothenburg. The distance is approximately 60 km, and the connection is implemented in the Swedish University Computer Network. The sites are connected through an active flexible communication network where each optical channel can be configured with terminal equipment based on the user needs. The network is implemented with unidirectional optical amplifiers and duplex fibers. The signal quality and the stability when sending an optical coherent frequency utilizing a wavelength in a DWDM system fiber pair, is evaluated within this work. The aim of the system is to be ultra-stable which corresponds to a stability of 10-13 for t = 1 s (Overlapping Allan Variance), as well as providing the ability to distribute monitored ultra-stable frequency with a future traceability to UTC (SP) to multiple users within the future network. This paper describes the current status and results from the frequency transfer between SP and Chalmers.
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| 10. |
- Ebenhag, Sven-Christian, et al.
(författare)
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Implementation of an optical fiber frequency distribution via commercial DWDM
- 2016
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Ingår i: 2016 IEEE International Frequency Control Symposium (IFCS). - 1075-6787. - 9781509020911
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Konferensbidrag (refereegranskat)abstract
- The rapid development in communication infrastructure over the past decades entails an increasing dependence on time and frequency, as well as its redundant distribution. This places demands not only on already existing distribution methods, but also on the development of new ones to meet future needs. To meet these demands several research groups are working on high performance fiber-based frequency transfer techniques. The best achieved performance so far is the techniques using a single bi-directional fiber connection, with customized bi-directional optical amplifiers [1]. The objective of this project is to develop a method that is compatible with data communication in DWDM-systems, i.e. using the existing infrastructure, as well as to be complementary technique for time and frequency distribution. Even though it is likely to have worse performance than the bi-directional system in terms of frequency stability, it will allow for the impassable obligation to follow the deployed structure of telecom networks. The establishment and early results of the non-stabilized link has been previously presented [2, 3]. The ongoing evaluation and improvement will be aimed at finding relevant performance specifications for a connection using this technique. The work presented here is the most recent results of the frequency transfer and discusses the future plans for the fiber connection, including the added time transfer method. If proven successful, the long-term objective is to establish a distribution network for optical frequency references in Sweden.
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