| 1. |
- Alijagic, Andi, 1992-, et al.
(författare)
-
Particle Safety Assessment in Additive Manufacturing : From Exposure Risks to Advanced Toxicology Testing.
- 2022
-
Ingår i: Frontiers in Toxicology. - : Frontiers Media S.A.. - 2673-3080. ; 4
-
Forskningsöversikt (refereegranskat)abstract
- Additive manufacturing (AM) or industrial three-dimensional (3D) printing drives a new spectrum of design and production possibilities; pushing the boundaries both in the application by production of sophisticated products as well as the development of next-generation materials. AM technologies apply a diversity of feedstocks, including plastic, metallic, and ceramic particle powders with distinct size, shape, and surface chemistry. In addition, powders are often reused, which may change the particles' physicochemical properties and by that alter their toxic potential. The AM production technology commonly relies on a laser or electron beam to selectively melt or sinter particle powders. Large energy input on feedstock powders generates several byproducts, including varying amounts of virgin microparticles, nanoparticles, spatter, and volatile chemicals that are emitted in the working environment; throughout the production and processing phases. The micro and nanoscale size may enable particles to interact with and to cross biological barriers, which could, in turn, give rise to unexpected adverse outcomes, including inflammation, oxidative stress, activation of signaling pathways, genotoxicity, and carcinogenicity. Another important aspect of AM-associated risks is emission/leakage of mono- and oligomers due to polymer breakdown and high temperature transformation of chemicals from polymeric particles, both during production, use, and in vivo, including in target cells. These chemicals are potential inducers of direct toxicity, genotoxicity, and endocrine disruption. Nevertheless, understanding whether AM particle powders and their byproducts may exert adverse effects in humans is largely lacking and urges comprehensive safety assessment across the entire AM lifecycle-spanning from virgin and reused to airborne particles. Therefore, this review will detail: 1) brief overview of the AM feedstock powders, impact of reuse on particle physicochemical properties, main exposure pathways and protective measures in AM industry, 2) role of particle biological identity and key toxicological endpoints in the particle safety assessment, and 3) next-generation toxicology approaches in nanosafety for safety assessment in AM. Altogether, the proposed testing approach will enable a deeper understanding of existing and emerging particle and chemical safety challenges and provide a strategy for the development of cutting-edge methodologies for hazard identification and risk assessment in the AM industry.
|
|
| 2. |
- Brentel, Jonas, et al.
(författare)
-
Single-wavelength 40 Gb/s soliton field transmission experiments over 400 km fibre without in-line control
- 1999
-
Ingår i: OFC/IOOC 1999 - Optical Fiber Communication Conference and the International Conference on Integrated Optics and Optical Fiber Communication. - 155752582X ; 3, s. 121-124
-
Konferensbidrag (refereegranskat)abstract
- We report single-wavelength 40-Gbit/s soliton transmission over 400-km installed fiber lines in Sweden. Both polarization-division multiplexed and parallel solitons were transmitted. The system performance is dominated by the polarization-mode dispersion.
|
|
| 3. |
- Kolltveit, Erling, et al.
(författare)
-
Single-wavelength 40 Gbit/s soliton field transmission experiment over 400 km of installed fibre
- 1999
-
Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 1350-911X .- 0013-5194. ; 35:1, s. 75-76
-
Tidskriftsartikel (refereegranskat)abstract
- 40Gbit/s soliton transmission over 400km (57km amplifier spacing) of installed lines without in-line control has been achieved. The maximum transmission penalties for parallel polarised and polarisation division multiplexed soliton transmission were ∼4 and 1dB, respectively. The transmission distance is the longest ever reported for a field trial with a single wavelength bit rate > 20Gbit/s for any optical transmission format. The polarisation mode dispersion was numerically found to completely dominate the system performance.
|
|
| 4. |
- Mazur, Mikael, 1990, et al.
(författare)
-
Field Trial of FPGA-Based Real-Time Sensing Transceiver over 524km of Live Aerial Fiber
- 2023
-
Ingår i: Optical Fiber Communication Conference, OFC 2023. - 9781957171180
-
Konferensbidrag (refereegranskat)abstract
- We perform fiber sensing over a 524 km live network using a real-time coherent transceiver prototype. Polarization and length changes from the link consisting exclusively of aerial fiber wound around high-voltage power cables are continuously monitored.
|
|
| 5. |
- Mazur, Mikael, 1990, et al.
(författare)
-
Real-Time Monitoring of Cable Break in a Live Network using a Coherent Transceiver Prototype
- 2024
-
Ingår i: Optical Fiber Communication Conference, OFC 2024. - 9781957171326
-
Konferensbidrag (refereegranskat)abstract
- We monitor a 524-km live network link using an real-time FPGA-based sensing-capable transceiver prototype during a human-caused cable break. Polarization sensing data shows minute-level potential break warning precursors, offering outage mitigation prospects.
|
|
| 6. |
- Ahmad, Tauseef, 1986, et al.
(författare)
-
Methodology for Power-Aware Coherent Receiver Design
- 2013
-
Ingår i: Optics InfoBase Conference Papers. - 2162-2701. ; , s. SPT4D.4-
-
Konferensbidrag (refereegranskat)abstract
- We describe a methodology to design and evaluate DSP hardware for a coherent receiver. Important parameters that can be assessed include DSP power consumption and chip area.
|
|
| 7. |
- Björk, Magnus, 1977, et al.
(författare)
-
Exposed Datapath for Efficient Computing
- 2006
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- We introduce FlexCore, which is the first exemplar of a processor based on the FlexSoC processor paradigm. TheFlexCore utilizes an exposed datapath for increased performance. Microbenchmarks yield a performance boost of a factor of two over a traditional five-stage pipeline with the same functional units as the FlexCore.We describe our approach to compiling for the FlexCore.A flexible interconnect allows the FlexCore datapath to bedynamically reconfigured as a consequence of code generation. Additionally, specialized functional units may be introduced and utilized within the same architecture and compilation framework. The exposed datapath requires a wide control word. The conducted evaluation of two micro benchmarks confirms that this increases the instruction bandwidth and memory footprint. This calls for an efficient instruction decoding as proposed in the FlexSoC paradigm.
|
|
| 8. |
|
|
| 9. |
- Börjeson, Erik, 1984, et al.
(författare)
-
Circuit Implementation of Pilot-Based Dynamic MIMO Equalization for Coupled-Core Fibers
- 2024
-
Ingår i: Optical Fiber Communication Conference, OFC 2024. - 9781957171326
-
Konferensbidrag (refereegranskat)abstract
- We explore ASIC implementation for pilot-based MIMO equalizers for coupled-core transmission, considering chip area scaling trends and performance impact of time-dependent drift. For a system with 28-GBd subcarriers, an equalizer for 8 × 8 is 5.3 times larger than for 2 × 2.
|
|
| 10. |
- Ebenhag, Sven-Christian, 1976, et al.
(författare)
-
Two-way coherent frequency transfer in a commercial DWDM communication network in Sweden
- 2015
-
Ingår i: 2015 Joint Conference of the IEEE International Frequency Control Symposium and the European Frequency and Time Forum, FCS 2015 - Proceedings. - 1075-6787. - 9781479988662 ; , s. 276-279
-
Konferensbidrag (refereegranskat)abstract
- An experimental fiber link is being established between SP Technical Research Institute of Sweden in Boras and Chalmers University of Gothenburg in Sweden. The one way fiber length is about 60 km and implemented in SUNET (Swedish University Network). The aim of the project is to evaluate the signal quality when sending a stable optical frequency utilizing a wavelength in a DWDM (Dense Wavelength Division Multiplexing) system fiber pair. The experiment uses a channel in the DWDM with the wavelength of 1542.14 nm. This wavelength is within the C band and is therefore compatible with common Erbium doped amplifiers in this network. Another aim of the system is to be ultra-stable which corresponds to a stability of 1×10-13 for τ = 1 s as well as providing the ability to distribute monitored ultra-stable frequency with a future traceability to UTC (SP) (National realization of Universal Time Coordinated within Sweden) to multiple users within the network. Measurements of an optical frequency transfer using a fiber-link based on unidirectional light signals in parallel fibers have shown promising results in a free-running setup and in a lab environment. The fractional frequency stability, analyzed as the Overlapping Allan deviation, is approximately 3×10-13 at τ = 10 s and almost 1×10-14 at 105 s.
|
|
| 11. |
- Ek, Staffan, et al.
(författare)
-
Relative Age Effect of Sport Academy Adolescents, a Physiological Evaluation
- 2020
-
Ingår i: Sports. - Basel : MDPI. - 2075-4663. ; 8:1
-
Tidskriftsartikel (refereegranskat)abstract
- The relationship between birth quarter distribution and physiological characteristics related to athletic skills, in adolescent sport academy students has not been fully investigated. In a cross-sectional study, we recruited 86 boys and 52 girls aged 12-14 years during their first term at a sport academy school. We measured body size, cardiac size, pulmonary function, body composition, lower body power, cardiorespiratory fitness parameters, and running endurance by standard methods and analyzed these estimates in relation to birth quarter by ANOVA. Birth quarter distribution in our cohort was compared with birth quarter distribution in the same ages in the whole of Sweden and analyzed by logistic regression. The academy had an overrepresentation of students born in the first quartile of the year compared to those born in the last quartile (odds ratio 2.3 (95% CI: 1.1-4.7)). When comparing the physiological characteristics between birth quarters, uniformity is prominent since out of 26 performed physiological and anthropometric tests only four showed statistically significant group differences. We thus believe that the selection process to the sport academy favours athletes with higher chronological age, i.e., a so-called relative age effect is present. © 2020 MDPI (Basel, Switzerland).
|
|
| 12. |
- Fougstedt, Christoffer, 1990, et al.
(författare)
-
ASIC Implementation of Time-Domain Digital Back Propagation for Coherent Receivers
- 2018
-
Ingår i: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 30:13, s. 1179-1182
-
Tidskriftsartikel (refereegranskat)abstract
- Digital back propagation (DBP) is often proposed and implemented offline for the mitigation of nonlinear impairments in long-haul fiber communications. However, complexity in terms of chip area and power consumption in a realistic application-specific integrated circuit implementation is yet to be determined. Here, we implement time-domain DBP (TD-DBP) in a 28-nm fully-depleted silicon-on-insulator process technology, considering digital implementation aspects such as limited-resolution arithmetic and finite-length filters. We choose as example a coherent optical transmission system, viz. a single-channel, single-polarization, and 20-GBd 16-QAM system, for which the DBP is known to perform well. For the considered system, we find that the TD-DBP can enable a reach increase from 3400 to 5300 km, at a power dissipation of <20 W (or, conversely, an energy dissipation of <230 pJ/bit), at a pre-FEC BER of 10-2.
|
|
| 13. |
|
|
| 14. |
- Fougstedt, Christoffer, 1990, et al.
(författare)
-
Time-Domain Digital Back Propagation: Algorithm and Finite-Precision Implementation Aspects
- 2017
-
Ingår i: Optics InfoBase Conference Papers. - 2162-2701. - 9781943580231 ; , s. Article no 7937325-
-
Konferensbidrag (refereegranskat)abstract
- We propose a nonlinear mitigation algorithm designed from an ASIC perspective, and analyze implementation aspects. Given 9 signal and 11 coefficient bits, reach is increased by 105% compared to linear compensation in single-channel 16-QAM transmission.
|
|
| 15. |
- Hedekvist, Per Olof E, 1967, et al.
(författare)
-
Fiber four-wave mixing demultiplexing with inherent parametric amplification
- 1997
-
Ingår i: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8724 .- 1558-2213. ; 15:11, s. 2051-2058
-
Tidskriftsartikel (refereegranskat)abstract
- We present an all-optical time-division demultiplexer with 22 dB conversion efficiency, using four-wave mixing (FWM) at 1550 nm in a single-mode dispersion-shifted fiber. Error-free demultiplexing of 20 Gb/s data to 10 Gb/s is obtained, with 1.4 dB power penalty at BER = 10-9. We also derive theoretical expressions for the conversion efficiency, the maximum bit rate that is possible to demux and the shape of the switching window. In particular we emphasize the importance of phase-matching in order to achieve a flat switching window. Furthermore the pump must remain undepleted to avoid a detrimental reduction of the extinction ratio due to instantaneous parametric gain saturation.
|
|
| 16. |
- Hedekvist, Per Olof E, 1967, et al.
(författare)
-
Polarization dependence and efficiency in a fiber four-wave mixing phase conjugator with orthogonal pump waves
- 1996
-
Ingår i: IEEE Photonics Technology Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1041-1135 .- 1941-0174. ; 8:6, s. 776-778
-
Tidskriftsartikel (refereegranskat)abstract
- We study the influence of pump separation on polarization dependence and on conversion efficiency in a fiberbased optical phase-conjugator with two orthogonal pump waves at different wavelengths. The polarization dependence is found to be minimized when the pump wavelength separation is small. Furthermore, both theory and experiments show that the efficiency is maximized if the signal wavelength is located close to one of the pumps.
|
|
| 17. |
- Kan, Haorui, et al.
(författare)
-
Digital Emulation of Time-Varying PMD for Real-Time DSP Evaluations
- 2021
-
Ingår i: Asia Communications and Photonics Conference, ACP. - 2162-108X. - 9781957171005 ; M4H
-
Konferensbidrag (refereegranskat)abstract
- We introduce a digital PMD emulator to accelerate BER analysis of coherent receiver DSPs. The emulator creates parameterizable, time-varying impairments, which we use to demonstrate real-time analysis of a CMA equalizer.
|
|
| 18. |
|
|
| 19. |
|
|
| 20. |
|
|
| 21. |
- Li, Jie, 1967, et al.
(författare)
-
0.5 Tbit/s eye-diagram measurement by optical sampling using XPM-induced wavelength shifting in highly nonlinear fiber
- 2003
-
Ingår i: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 16:2, s. 566-568
-
Tidskriftsartikel (refereegranskat)abstract
- In this letter, we report on a novel all-optical sampling scheme using cross-phase modulation-induced wavelength shifting and optical filtering. Up to 500-Gb/s optical signal eye-diagram measurements have been demonstrated for the first time with a temporal resolution of 0.7 ps. Signal operational wavelength range covering basically the whole erbium-doped fiber amplifier gain range (1535-1569 nm) with temporal resolutions equal to or less than 1 ps was also demonstrated in the experiment. These results show that the sampling system is suitable for directly monitoring and evaluating ultrahigh bit-rate optical time-division multiplexed data at or above 160 Gb/s.
|
|
| 22. |
- Lundberg, Lars, 1989, et al.
(författare)
-
Power Consumption of a Minimal-DSP Coherent Link with a Polarization Multiplexed Pilot-Tone
- 2016
-
Ingår i: 42nd European Conference and Exhibition on Optical Communications, September 18-22, 2016, Düsseldorf. - 9783800742745
-
Konferensbidrag (refereegranskat)abstract
- We experimentally study the trade-off between performance and DSP power consumption. While minimal DSP allows transmission of 16QAM at 5 GBaud, the symbol rate can be increased if anextra equalizer is added, leading to energy savings in optical components.
|
|
| 23. |
- Lundberg, Lars, 1989, et al.
(författare)
-
Power Consumption Savings Through Joint Carrier Recovery for Spectral and Spatial Superchannels
- 2018
-
Ingår i: European Conference on Optical Communication, ECOC. ; 2018-September
-
Konferensbidrag (refereegranskat)abstract
- The power consumption of a circuit implementation of a master-slave carrier recovery scheme is studied. Slave power consumption is 27% of master power for 16QAM and 13% for 64QAM, enabling power savings approaching 0.7W per channel through joint processing.
|
|
| 24. |
- Romon Sagredo, Rafael, et al.
(författare)
-
Waveform Memory for Real-Time FPGA Test of Fiber-Optic Receiver DSPs
- 2022
-
Ingår i: 2022 IEEE Nordic Circuits and Systems Conference, NORCAS 2022 - Proceedings.
-
Konferensbidrag (refereegranskat)abstract
- Verification of advanced circuit implementations poses many challenges. For complex digital signal processing (DSP) circuits, logic simulations may be prohibitively slow when non-stationary scenarios are considered. A real-time emulation technique like the Fiber-on-Chip (FoC) approach can significantly speed up DSP logic verification. However, a potential weakness with this type of emulation is that it does not use data obtained from experiments, but synthetically creates test data. We introduce a waveform memory, which can be integrated with FoC systems and similar emulators, and which allows measured waveforms to be stored and fed to DSP circuits under test. We perform real-time FPGA experiments where we evaluate a carrier-phase recovery (CPR) module that is tested using either waveform data or synthetic data. Our results for the two different data sets show that the CPR module behaves similarly, both qualitatively and quantitatively, which indicates that the synthetic phase-noise model is a valid replacement of measured data.
|
|
| 25. |
- Sheikh, Alireza, 1989, et al.
(författare)
-
Dispersion Compensation Filter Design Optimized for Robustness and Power Efficiency
- 2015
-
Ingår i: Signal Processing in Photonics Communications, SPPCom 2015; Boston, MA; United States; 27 June 2015 through 1 July 2015. - 9781557520005 ; , s. SpT3D.2-
-
Konferensbidrag (refereegranskat)abstract
- We present an optimized CD compensation filter with improved performance and increased resilience to quantization errors. The filter is given in closed form based on a constrained least-squares problem.
|
|
| 26. |
- Sheikh, Alireza, 1989, et al.
(författare)
-
Dispersion Compensation FIR Filter with Improved Robustness to Coefficient Quantization Errors
- 2016
-
Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 34:22, s. 5110-5117
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we propose a new finite impulseresponse (FIR) filter for chromatic dispersion compensation which is given in closed form. We identify a relation between the out-of-band gain and the in-band error when the filter is implemented with finite-precision arithmetic. In particular, a large out-of-band gain makes the filter more sensitive tocoefficient quantization errors due to finite precision digital signal processing. To improve robustness to coefficient quantization errors, our proposed filter is designed based on confining the out-of-band gain. By means of simulations, we show that our filter outperforms other existing FIR filters. The performance gain improves with increasing modulation order and decreasing number of bits used to represent the filter taps.
|
|
| 27. |
- Szczerba, Krzysztof, 1985, et al.
(författare)
-
Impact of Forward Error Correction on Energy Consumption of VCSEL-based Transmitters
- 2015
-
Ingår i: 41st European Conference on Optical Communication, ECOC 2015, Valencia, Spain, 27 September - 1 October 2015. - 9788460817413 ; 2015-November
-
Konferensbidrag (refereegranskat)abstract
- We present an analysis of the effect of FEC on energy consumption of VCSEL based transmitters for short-range optical links. We show that a low-complexity FEC can reduce the overall energy consumption of the transmitter.
|
|
| 28. |
|
|
| 29. |
- Wu, Ping-Hsun, et al.
(författare)
-
The association between Single Nucleotide Polymorphisms of Klotho Gene and Mortality in Elderly Men: The MrOS Sweden Study
- 2020
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 10:1
-
Tidskriftsartikel (refereegranskat)abstract
- The Klotho (KL) gene is involved in phosphate homeostasis. Polymorphisms in this gene have been reported to be associated with the risk of cardiovascular disease. Here we used computational tools to predict the damage-associated single nucleotide polymorphisms (SNPs) in the human KL gene. We further investigated the association of SNPs in the KL gene and mortality in the Swedish multicenter prospective Osteoporotic Fractures in Men (MrOS) cohort. This study included 2921 men (aged 69-81 years) with mean 4.49 +/- 1.03 years follow-up. 18 SNPs in the KL gene were genotyped using Sequenom. These SNPs were identified by in silico tools for the coding and noncoding genome to predict the damaging SNPs. After quality analyses, SNPs were analyzed for mortality risk using two steps approach on logistic regression model screening and then Cox regression model confirmation. Two non-synonymous SNPs rs9536314 and rs9527025 were found to be potentially damaging SNPs that affect KL protein stability and expression. However, these two SNPs were not statistically significantly associated with all-cause mortality (crude Hazard ratio [HR] 1.72, 95% confidence interval [CI] 0.96-3.07 in rs9536314; crude HR 1.82, 95% CI 0.998-3.33 in rs9527025) or cardiovascular mortality (crude HR 1.52, 95% CI 0.56-4.14 in rs9536314; crude HR 1.54, 95% CI 0.55-4.33 in rs9527025) in additive model using Cox regression analysis. In conclusion, these two potentially damaging SNPs (rs9536314 and rs9527025) in the KL gene were not associated with all-cause mortality or cardiovascular mortality in MrOs cohort. Larger scales studies and meta-analysis are needed to confirm the correlation between polymorphisms of the KL gene and mortality.
|
|
| 30. |
- Zhang, Renyun, et al.
(författare)
-
Soap-film coating : High-speed deposition of multilayer nanofilms
- 2013
-
Ingår i: Scientific Reports. - Nature Publishing Group : Springer Science and Business Media LLC. - 2045-2322. ; 3, s. Art. no. 1477-
-
Tidskriftsartikel (refereegranskat)abstract
- The coating of thin films is applied in numerous fields and many methods are employed for the deposition of these films. Some coating techniques may deposit films at high speed; for example, ordinary printing paper is coated with micrometre-thick layers of clay at a speed of tens of meters per second. However, to coat nanometre thin films at high speed, vacuum techniques are typically required, which increases the complexity of the process. Here, we report a simple wet chemical method for the high-speed coating of films with thicknesses at the nanometre level. This soap-film coating technique is based on forcing a substrate through a soap film that contains nanomaterials. Molecules and nanomaterials can be deposited at a thickness ranging from less than a monolayer to several layers at speeds up to meters per second. We believe that the soap-film coating method is potentially important for industrial-scale nanotechnology.
|
|
| 31. |
- Agrell, Erik, 1965, et al.
(författare)
-
Capacity of a nonlinear optical channel with finite memory
- 2014
-
Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 32:16, s. 2862-2876
-
Tidskriftsartikel (refereegranskat)abstract
- The channel capacity of a nonlinear, dispersive fiber-optic link is revisited. To this end, the popular Gaussian noise (GN) model is extended with a parameter to account for the finite memory of realistic fiber channels. This finite-memory model is harder to analyze mathematically but, in contrast to previous models, it is valid also for nonstationary or heavy-tailed input signals. For uncoded transmission and standard modulation formats, the new model gives the same results as the regular GN model when the memory of the channel is about ten symbols or more. These results confirm previous results that the GN model is accurate for uncoded transmission. However, when coding is considered, the results obtained using the finite-memory model are very different from those obtained by previous models, even when the channel memory is large. In particular, the peaky behavior of the channel capacity, which has been reported for numerous nonlinear channel models, appears to be an artifact of applying models derived for independent input in a coded (i.e., dependent) scenario. © 1983-2012 IEEE.
|
|
| 32. |
- Agrell, Erik, 1965, et al.
(författare)
-
Influence of Behavioral Models on Multiuser Channel Capacity
- 2015
-
Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 33:17, s. 3507-3515
-
Tidskriftsartikel (refereegranskat)abstract
- In order to characterize the channel capacity of a wavelength channel in a wavelength-division multiplexed (WDM) system, statistical models are needed for the transmitted signals on the other wavelengths. For example, one could assume that the transmitters for all wavelengths are configured independently of each other, that they use the same signal power, or that they use the same modulation format. In this paper, it is shown that these so-called behavioral models have a profound impact on the single-wavelength achievable information rate. This is demonstrated by establishing, for the first time, upper and lower bounds on the maximum achievable rate under various behavioral models, for a rudimentary WDM channel model.
|
|
| 33. |
- Agrell, Erik, 1965, et al.
(författare)
-
Modulation and detection for multicore superchannels with correlated phase noise [Invited]
- 2018
-
Ingår i: 2018 Conference on Lasers and Electro-Optics, CLEO 2018 - Proceedings. ; Part F94-CLEO_SI 2018
-
Konferensbidrag (refereegranskat)abstract
- SDM fibers offer new opportunities and challenges for joint transmitter and receiver processing. We review multidimensional modulation and detection theory, describe algorithms for phase tracking and detection over spatial superchannels, and present some experimental results.
|
|
| 34. |
- Agrell, Erik, 1965, et al.
(författare)
-
On the symbol error probability of regular polytopes
- 2011
-
Ingår i: IEEE Transactions on Information Theory. - 0018-9448 .- 1557-9654. ; 57:6, s. 3411-3415
-
Tidskriftsartikel (refereegranskat)abstract
- An exact expression is derived for the symbol error probability when the vertices of the four-dimensional 24-cell are used for digital transmission in Gaussian noise. Corresponding expressions for other regular convex polytopes are summarized. Numerically stable versions of these error probabilities are also obtained. © 2011 IEEE.
|
|
| 35. |
|
|
| 36. |
- Agrell, Erik, 1965, et al.
(författare)
-
Power-efficient modulation formats in coherent transmission systems
- 2009
-
Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 27:22, s. 5115-5126
-
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.
|
|
| 37. |
- Agrell, Erik, 1965, et al.
(författare)
-
Roadmap of optical communications
- 2016
-
Ingår i: Journal of Optics. - : IOP Publishing. - 2040-8978 .- 2040-8986. ; 18:6
-
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.
|
|
| 38. |
- Agrell, Erik, 1965, et al.
(författare)
-
Roadmap on optical communications
- 2024
-
Ingår i: Journal of Optics. - 2040-8978 .- 2040-8986. ; 26:9
-
Forskningsöversikt (refereegranskat)abstract
- The Covid-19 pandemic showed forcefully the fundamental importance broadband data communication and the internet has in our society. Optical communications forms the undisputable backbone of this critical infrastructure, and it is supported by an interdisciplinary research community striving to improve and develop it further. Since the first ‘Roadmap of optical communications’ was published in 2016, the field has seen significant progress in all areas, and time is ripe for an update of the research status. The optical communications area has become increasingly diverse, covering research in fundamental physics and materials science, high-speed electronics and photonics, signal processing and coding, and communication systems and networks. This roadmap describes state-of-the-art and future outlooks in the optical communications field. The article is divided into 20 sections on selected areas, each written by a leading expert in that area. The sections are thematically grouped into four parts with 4-6 sections each, covering, respectively, hardware, algorithms, networks and systems. Each section describes the current status, the future challenges, and development needed to meet said challenges in their area. As a whole, this roadmap provides a comprehensive and unprecedented overview of the contemporary optical communications research, and should be essential reading for researchers at any level active in this field.
|
|
| 39. |
- Agrell, Erik, 1965, et al.
(författare)
-
Satellite constellations: Towards the nonlinear channel capacity
- 2012
-
Ingår i: 25th IEEE Photonics Conference, IPC 2012, Burlingame, 23 - 27 September 2012 [Invited]. - 9781457707315 ; , s. 316-317
-
Konferensbidrag (refereegranskat)abstract
- We present a family of adaptive constellations that, in a nonlinear optical fiber channel model, has a mutual information (modulation-constrained capacity) that does not decrease with signal power.
|
|
| 40. |
- Agrell, Erik, 1965, et al.
(författare)
-
WDM channel capacity and its dependence on multichannel adaptation models
- 2013
-
Ingår i: 2013 Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference, OFC/NFOEC [Invited]. - 9781479904570
-
Konferensbidrag (refereegranskat)abstract
- Optical multichannel systems are often characterized by the channel capacity of a single channel, assuming a certain adaptation behavior of the other channels. We investigate some common adaptation models, which lead to dramatically different capacities.
|
|
| 41. |
- Akhmediev, N., et al.
(författare)
-
Cherenkov radiation emitted by solitons in optical fibers
- 1995
-
Ingår i: Physical Review A - Atomic, Molecular, and Optical Physics. - 2469-9926 .- 2469-9934. ; 51:3, s. 2602-2607
-
Tidskriftsartikel (refereegranskat)abstract
- We demonstrate a simple, fully analytic method of calculating the amount of radiation emitted by optical solitons perturbed by higher-order dispersion effects in fibers and find good agreement with numerical results. It is pointed out that this radiation mechanism is analogous to the well-known Cherenkov radiation processes in nonlinear optics. © 1995 The American Physical Society.
|
|
| 42. |
- Akhmediev, N.N., et al.
(författare)
-
Radiationless optical solitons with oscillating tails
- 1994
-
Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018. ; 110:5-6, s. 540-544
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate, analytically and numerically, stationary soliton-like pulse propagation in nonlinear optical fibres, taking into account the effects of fourth order dispersion. A new type of stationary stable soliton-like solution is found. A unique feature of this type of solution is their unusual asymptotic behaviour (oscillating tails). © 1994.
|
|
| 43. |
- Alfredsson, Arni, 1989, et al.
(författare)
-
On the Impact of Intercore Skew on Joint-Core Carrier-Phase Estimation
- 2019
-
Ingår i: European Conference on Optical Communication, ECOC. - : Institution of Engineering and Technology. ; 2019:CP765
-
Konferensbidrag (refereegranskat)abstract
- The impact of intercore skew on joint-core carrier-phase estimation in multicore-fiber transmission is studied. It is shown that the performance degradation is not dependent on the combined linewidth of the light-source laser and the local oscillator, but rather the ratio between the two linewidths.
|
|
| 44. |
- Alfredsson, Arni, 1989, et al.
(författare)
-
On the Performance of Joint-Core Carrier-Phase Estimation in the Presence of Intercore Skew
- 2019
-
Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 37:20, s. 5291-5298
-
Tidskriftsartikel (refereegranskat)abstract
- The sharing of lasers in space-division multiplexed multicore-fiber transmission yields correlated phase noise across the spatial channels. As a result, system performance can be improved through the use of joint-core carrier-phase estimation (CPE). However, the presence of intercore skew can reduce the potential of such schemes. This paper studies the effects of skew on pilot-aided joint-core CPE, where via simulations, it is shown that joint-core processing can be made to perform similarly to or better than separate-core processing for any amount of skew. It is shown that for a given signal-to-noise ratio (SNR) and skew, the performance of joint-core CPE relative to separate-core CPE is highly dependent on the ratio of the light-source linewidth to the local oscillator (LO) linewidth. In general, the performance of joint-core CPE in the presence of skew improves as the LO linewidth decreases compared to the light-source laser linewidth, assuming that the spatial channels are digitally realigned at the receiver.
|
|
| 45. |
- Alfredsson, Arni, 1989, et al.
(författare)
-
Optimization of Transmitter-Side Signal Rotations in the Presence of Laser Phase Noise
- 2020
-
Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 38:15, s. 3850-3858
-
Tidskriftsartikel (refereegranskat)abstract
- The effects of transmitter-side multidimensional signal rotations on the performance of multichannel optical transmission are studied in the presence of laser phase noise. In particular, the laser phase noise is assumed to be uncorrelated between channels. To carry out this study, a simple multichannel laser-phase-noise model that has been experimentally validated for weakly-coupled multicore-fiber transmission is considered. As the considered rotation scheme is intended to work in conjunction with receiver-side carrier phase estimation (CPE), the model is modified to further assume that imperfect CPE has taken place, leaving residual phase noise in the processed signal. Based on this model, two receiver structures are derived and used to numerically optimize transmitter-side signal rotations through Monte Carlo simulations. For reasonable amounts of residual phase noise, rotations based on Hadamard matrices are found to be near-optimal for transmission of four-dimensional signals. Furthermore, Hadamard rotations can be performed for any dimension that is a power of two. By exploiting this property, an increase of up to 0.25 bit per complex symbol in an achievable information rate is observed for transmission of higher-order constellations.
|
|
| 46. |
- Alfredsson, Arni, 1989, et al.
(författare)
-
Phase-Noise Compensation for Spatial-Division Multiplexed Transmission
- 2017
-
Ingår i: Optics InfoBase Conference Papers. - 2162-2701. ; Part F40-OFC 2017
-
Konferensbidrag (refereegranskat)abstract
- The problem of correlated phase noise in spatial-division multiplexed transmission is studied. To compensate for the phase noise, an algorithm for joint-core phase-noise estimation and symbol detection is proposed, which outperforms conventional methods.
|
|
| 47. |
- Alfredsson, Arni, 1989, et al.
(författare)
-
Pilot-Aided Joint-Channel Carrier-Phase Estimation in Space-Division Multiplexed Multicore Fiber Transmission
- 2019
-
Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 37:4, s. 1133-1142
-
Tidskriftsartikel (refereegranskat)abstract
- The performance of pilot-aided joint-channel carrier-phase estimation (CPE) in space-division multiplexed multicore fiber (MCF) transmission with correlated phase noise is studied. To that end, a system model describing uncoded MCF transmission where the phase noise comprises a common laser phase noise, in addition to core- and polarization-specific phase drifts, is introduced. It is then shown that the system model can be regarded as a special case of a multidimensional random-walk phase-noise model. A pilot-aided CPE algorithm developed for this model is used to evaluate two strategies, namely joint-channel and per-channel CPE. To quantify the performance differences between the two strategies, their respective phase-noise tolerances are assessed through Monte Carlo simulations of uncoded transmission for different modulation formats, pilot overheads, laser linewidths, numbers of spatial channels, and degrees of phase-noise correlation across the channels. For 20 GBd transmission with 200 kHz combined laser linewidth and 1% pilot overhead, joint-channel CPE yields up to 3.4 dB improvement in power efficiency or 25.5% increased information rate. Moreover, through MCF transmission experiments, the system model is validated and the strategies are compared in terms of bit-error-rate performance versus transmission distance for uncoded transmission of different modulation formats. Up to 21% increase in transmission reach is observed for 1% pilot overhead through the use of joint-channel CPE.
|
|
| 48. |
- Alfredsson, Arni, 1989, et al.
(författare)
-
Pilot Distributions for Joint-Channel Carrier-Phase Estimation in Multichannel Optical Communications
- 2020
-
Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 38:17, s. 4656-4663
-
Tidskriftsartikel (refereegranskat)abstract
- Joint-channel carrier-phase estimation can improve the performance of multichannel optical communication systems. In the case of pilot-aided estimation, the pilots are distributed over a two-dimensional channel-time symbol block that is transmitted through multiple channels. However, suboptimal pilot distributions reduce the effectiveness of the carrier-phase estimation and thus result in unnecessary pilot overhead, which reduces the overall information rate of the system. It is shown that placing pilots identically in all channels is suboptimal in general. By instead optimizing the pilot distribution, the mean squared error of the phase-noise estimates can be decreased by over 90% in some cases. Moreover, it is shown that the achievable information rate can be increased by up to 0.05, 0.16, and 0.41 bits per complex symbol for dual-polarization 20 GBd transmission of 64-ary, 256-ary, and 1024-ary quadrature amplitude modulation over 20 four-dimensional channels, respectively, assuming a total laser linewidth of 200 kHz.
|
|
| 49. |
- Alfredsson, Arni, 1989, et al.
(författare)
-
Pilot Distributions for Phase Tracking in Space-Division Multiplexed Systems
- 2017
-
Ingår i: European Conference on Optical Communication, ECOC. ; 2017-September
-
Konferensbidrag (refereegranskat)abstract
- Several pilot distributions are compared for pilot-aided joint-core phase tracking in space-division multiplexed transmission affected by correlated phase noise. Results show that the best choice of distribution can reduce the bit error rate by a factor up to 170.
|
|
| 50. |
- Alic, N., et al.
(författare)
-
Benefits of Joint Statistics in MLSD-Equalized Transmission
- 2009
-
Ingår i: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 21:8, s. 495-497
-
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.
|
|
