| 1. |
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| 2. |
- Schael, S, et al.
(författare)
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Precision electroweak measurements on the Z resonance
- 2006
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Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
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Forskningsöversikt (refereegranskat)abstract
- We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLID experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, m(Z) and Gamma(Z), and its couplings to fermions, for example the p parameter and the effective electroweak mixing angle for leptons, are precisely measured: m(Z) = 91.1875 +/- 0.0021 GeV, Gamma(Z) = 2.4952 +/- 0.0023 GeV, rho(l) = 1.0050 +/- 0.0010, sin(2)theta(eff)(lept) = 0.23153 +/- 0.00016. The number of light neutrino species is determined to be 2.9840 +/- 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, m(t) = 173(+10)(+13) GeV, and the mass of the W boson, m(W) = 80.363 +/- 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of m(t) and m(W), the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level. (c) 2006 Elsevier B.V. All rights reserved.
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| 3. |
- Halim, Joseph, 1985-
(författare)
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Synthesis and Characterization of 2D Nanocrystals and Thin Films of Transition Metal Carbides (MXenes)
- 2014
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Two dimensional (2D) materials have received growing interest because of their unique properties compared to their bulk counterparts. Graphene is the archetype 2D solid, but other materials beyond graphene, such as MoS2 and BN have become potential candidates for several applications. Recently, a new family of 2D materials of early transition metal carbides and carbonitrides (Ti2CTx, Ti3C2Tx, Ti3CNTx, Ta4C3Tx, and more), labelled MXenes, has been discovered, where T stands for the surface-terminating groups.Before the present work, MXenes had only been synthesized in the form of exfoliated and delaminated powders, which is not suitable for electronic applications. In this thesis, I demonstrate the synthesis of MXenes as epitaxial thin films, a more suitable form for electronic and photonic applications. Results show that 2D epitaxial Ti3C2Tx films - produced by HF and NH4HF2 etching of magnetron sputter-grown Ti3AlC2 - exhibit metallic conductive behaviour down to 100 K and are 90% transparent to light in the visible-infrared range. The results from this work may open the door for MXenes as potential candidates for transparent conductive electrodes as well as in electronic, photonic and sensing applications.MXenes have been shown to intercalate cations and molecules between their layers that in turn can alter the surface termination groups. There is therefore a need to study the surface chemistries of synthetized MXenes to be able to study the effect of intercalation as well as altering the surface termination groups on the electronic structure and chemical states of the elements present in MXene layers. X-ray Photoelectron Spectroscopy (XPS) in-depth characterization was used to investigate surface chemistries of Ti3C2Tx and Ti2CTx. This thesis includes the discussion of the effect of Ar+ sputtering and the number of layers on the surface chemistry of MXenes. This study serves as a baseline for chemical modification and tailoring of the surface chemistry groups to potential uses and applications.New MXene phases, Nb2CTx and V2CTx, are shown in this thesis to be produced from HF chemical etching of Nb2AlC and V2AlC powders. Characterization of the produced MXenes was carried out using Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Transmission Electron Microscope (TEM) and XPS. Nb2CTx and V2CTx showed promising performance as electrodes for Li-ion batteries.In this thesis, electrochemical etching was used in an attempt to produce 2D metal carbides (MXene) from their ternary metal carbides, Ti3SiC2, Ti3AlC2 and Ti2AlC MAX phases. MAX phases in the form of highly dense bulk produced by Hot Isostatic Press. Several etching solutions were used such as HF, NaCl and HCl. Unlike the HF chemical etching of MAX phases, which results in MXenes, the electrochemical etching resulted in Carbide Derived Carbon (CDC). Here, I show the characterization of the produced CDC using several techniques such as XRD, TEM, Raman spectroscopy, and XPS. Electrochemical characterization was performed in the form of cyclic voltammetry, which sheds light on the etching mechanism.
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| 4. |
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| 5. |
- Campbell, PJ, et al.
(författare)
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Pan-cancer analysis of whole genomes
- 2020
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 578:7793, s. 82-
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Tidskriftsartikel (refereegranskat)abstract
- Cancer is driven by genetic change, and the advent of massively parallel sequencing has enabled systematic documentation of this variation at the whole-genome scale1–3. Here we report the integrative analysis of 2,658 whole-cancer genomes and their matching normal tissues across 38 tumour types from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). We describe the generation of the PCAWG resource, facilitated by international data sharing using compute clouds. On average, cancer genomes contained 4–5 driver mutations when combining coding and non-coding genomic elements; however, in around 5% of cases no drivers were identified, suggesting that cancer driver discovery is not yet complete. Chromothripsis, in which many clustered structural variants arise in a single catastrophic event, is frequently an early event in tumour evolution; in acral melanoma, for example, these events precede most somatic point mutations and affect several cancer-associated genes simultaneously. Cancers with abnormal telomere maintenance often originate from tissues with low replicative activity and show several mechanisms of preventing telomere attrition to critical levels. Common and rare germline variants affect patterns of somatic mutation, including point mutations, structural variants and somatic retrotransposition. A collection of papers from the PCAWG Consortium describes non-coding mutations that drive cancer beyond those in the TERT promoter4; identifies new signatures of mutational processes that cause base substitutions, small insertions and deletions and structural variation5,6; analyses timings and patterns of tumour evolution7; describes the diverse transcriptional consequences of somatic mutation on splicing, expression levels, fusion genes and promoter activity8,9; and evaluates a range of more-specialized features of cancer genomes8,10–18.
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| 6. |
- Kanai, M, et al.
(författare)
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- 2023
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swepub:Mat__t
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| 7. |
- Clark, DW, et al.
(författare)
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Associations of autozygosity with a broad range of human phenotypes
- 2019
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Ingår i: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 10:1, s. 4957-
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Tidskriftsartikel (refereegranskat)abstract
- In many species, the offspring of related parents suffer reduced reproductive success, a phenomenon known as inbreeding depression. In humans, the importance of this effect has remained unclear, partly because reproduction between close relatives is both rare and frequently associated with confounding social factors. Here, using genomic inbreeding coefficients (FROH) for >1.4 million individuals, we show that FROH is significantly associated (p < 0.0005) with apparently deleterious changes in 32 out of 100 traits analysed. These changes are associated with runs of homozygosity (ROH), but not with common variant homozygosity, suggesting that genetic variants associated with inbreeding depression are predominantly rare. The effect on fertility is striking: FROH equivalent to the offspring of first cousins is associated with a 55% decrease [95% CI 44–66%] in the odds of having children. Finally, the effects of FROH are confirmed within full-sibling pairs, where the variation in FROH is independent of all environmental confounding.
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| 8. |
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| 9. |
- Fan, Yuchuan, et al.
(författare)
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Feedforward Neural Network-Based EVM Estimation : Impairment Tolerance in Coherent Optical Systems
- 2022
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Ingår i: IEEE Journal of Selected Topics in Quantum Electronics. - : Institute of Electrical and Electronics Engineers Inc.. - 1077-260X .- 1558-4542. ; 28:4
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Tidskriftsartikel (refereegranskat)abstract
- Error vector magnitude (EVM) is commonly used for evaluating the quality of m-ary quadrature amplitude modulation (mQAM) signals. Recently proposed deep learning techniques for EVM estimation extend the functionality of conventional optical performance monitoring (OPM). In this article, we evaluate the tolerance of our developed EVM estimation scheme against various impairments in coherent optical systems. In particular, we analyze the signal quality monitoring capabilities in the presence of residual in-phase/quadrature (IQ) imbalance, fiber nonlinearity, and laser phase noise. We use feedforward neural networks (FFNNs) to extract the EVM information from amplitude histograms of 100 symbols per IQ cluster signal sequence captured before carrier phase recovery. We perform simulations of the considered impairments, along with an experimental investigation of the impact of laser phase noise. To investigate the tolerance of the EVM estimation scheme to each impairment type, we compare the accuracy for three training methods: 1) training without impairment, 2) training one model for all impairments, and 3) training an independent model for each impairment. Results indicate a good generalization of the proposed EVM estimation scheme, thus providing a valuable reference for developing next-generation intelligent OPM systems.
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| 10. |
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| 11. |
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| 12. |
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| 13. |
- Jia, Shi, et al.
(författare)
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2 x 300 Gbit/s Line Rate PS-64QAM-OFDM THz Photonic-Wireless Transmission
- 2020
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Ingår i: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8724 .- 1558-2213. ; 38:17, s. 4715-4721
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Tidskriftsartikel (refereegranskat)abstract
- The proliferation of wireless broadband services have significantly raised the demand for high data rates. Due to the limited bandwidth of radio frequency (RF) bands that are currently in use for communication purposes, the choice of the 'Terahertz (THz) frequency region' (0.3-10 THz) is getting favored thanks to its merits of bringing together wireless and optical communications with photonics technologies. We report on an experimental demonstration of a hybrid THz photonic-wireless transmission based on a THz orthogonal polarization dual-antenna scheme. Probabilistic shaped 64-ary quadrature amplitude modulation based orthogonal frequency division multiplexing (64QAM-OFDM) modulation format is used to realize high transmission rate. A potential total system throughput of 612.65 Gbit/s (around 2 x 300 Gbit/s line rate) with an average net spectral efficiency of 4.445 bit/s/Hz per antenna is successfully achieved.
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| 14. |
- Li, Changle, 1992-
(författare)
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Ab Initio Investigation of Interfacial and Grain Boundary Properties of Metals and Alloys
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Phase interface (IF) and grain boundary (GB) are both common yet critical planar defects influencing the mechanical and physical properties of polycrystalline materials. Due to the complex nature of IFs and GBs in terms of structure and chemistry, determining the accurate excess energies associated with these defects is challenging for both experimental measurements and theoretical simulations. In this thesis, using first-principles methods, I make efforts towards establishing an efficient and robust model for predicting the IF and GB properties in elemental metals and complex multi-component alloys including the temperature and composition dependences.First I focus on the temperature dependent interfacial energy (IFE) for Cu-Co alloys. IFE plays a critical role in determining the nucleation and precipitate coarsening thermodynamics and kinetics. I start with assessing the phase diagram of Cu-Co alloys by ab initio calculations, which is used for establishing the composition-temperature relationship of precipitates and matrix. Calculations of the physical and thermodynamic properties for the ferromagnetic (FM) and paramagnetic (PM) $\ce{Cu}_{1-x}\ce{Co}_{x}$ solid solutions are performed using the exact muffin-tin orbital (EMTO) method in combination with the coherent potential approximation (CPA) for dealing chemical and magnetic randomness. This study demonstrates that the equilibrium volumes and magnetic states are crucial for a quantitative description of the thermodynamics of the Cu-Co system at temperatures up to 1400 K. The predicted ab initio Cu-Co phase diagram is in good agreement with the measurements and CALPHAD data. Then, the composition and magnetic dependent IFEs for a coherent $\ce{Cu}_{1-x}\ce{Co}_{x}$/$\ce{Cu}_{x}\ce{Co}_{1-x}$ interface are investigated at various magnetic states including FM, PM, and the mixed PM+FM states to account for the magnetic state change at different temperatures. Then, I translate the composition dependence of the IFE to the temperature dependence. The obtained results are in reasonable agreement with those obtained by experiments and thermodynamic calculations. The first part of the thesis provides an ab initio database for the IFEs in Cu-Co system and emphasizes the importance of understanding and properly describing various physical and thermodynamic quantities in different materials modeling approaches.The second focus of this thesis is on grain boundary energy (GBE). We calculate the GBEs for ten face-centered cubic (fcc) and seven body-centered cubic (bcc) metals. Various types of symmetric tilt GB structures ranging from twin boundary up to $\Sigma$19 coincident site lattice (CSL) boundaries are studied using the Vienna Ab initio Simulation Package (VASP). Ab initio results show a correlation between the GBEs of the same grain boundary structure in different fcc and bcc metals. Importantly, I show that the correlation factor is best determined by the ratio of the low-index surface energy. By using this correlation, the general GBEs of fcc and bcc metals are predicted at 0 K. Furthermore, using the Foiles's method, which assumes that the general GBE has a similar temperature dependence as the elastic modulus $c_{44}$, the general GBEs at elevated temperatures are predicted. The so obtained theoretical results show a good agreement with the available experimental data. Finally, the proposed method for predicting the general GBEs is applied to complex multicomponent alloys (austinite Fe-Cr-Ni and ferritic Fe-Cr alloys), yielding a parameterized prediction of the composition and temperature dependent GBE. After examining two common experimental methods used for determining the general GBEs, it is concluded that the two sets of experimental GBEs for fcc metals agree well with each other, while for bcc metals they correspond to different grain boundary structures and differ by a factor of 2. This part of the thesis introduces an effective and robust model for predicting the general GBEs of metals and alloys, facilitating grain boundary engineering for advanced alloy design. The third focus is on alloying GB segregation in complex alloys. Manganese (Mn) and Nickel (Ni) segregation behaviors at bcc Fe-Cr grain boundaries are investigated. In this segregation study, three GB structures, namely, $\Sigma$3(111), $\Sigma$9(114), and $\Sigma$11(332), are considered. First, a systematic comparison of the theoretical segregation energies for Mn and Ni solutes in pure Fe GBs is conducted between VASP and EMTO calculations. The EMTO results agree reasonably with VASP and previous theoretical data, indicating a reliable potential for capturing the solute segregation behaviors. Next, the Mn and Ni segregation energies at bcc Fe-Cr solid solution GBs are determined at various concentrations of the matrix and at the FM and PM states to account for the temperature effects on the magnetic state using the EMTO-CPA method. Strong magnetic effects on the segregation energy are observed. Particularly, it is found that the magnetic states of Mn atoms depend strongly on local chemical and structural environment, which has a remarkable effect on the segregation energy. It is found that Mn and Ni show different segregation tendencies at FM and PM states. This part of the thesis puts forward an attempt to investigate the solute segregation properties in complex solid solutions as compared to pure metal or dilute alloys, and improves our understanding of GB segregation in engineering alloys, like steels.
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| 15. |
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| 16. |
- Qiao, Mengyao, et al.
(författare)
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60 Gbit/s PAM-4 wireless transmission in the 310 GHz band with nonlinearity tolerant signal processing
- 2021
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 492
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Tidskriftsartikel (refereegranskat)abstract
- We experimentally demonstrate a terahertz (THz) photonic wireless transmission system in the 310 GHz band with four-level pulse amplitude modulation (PAM-4) signals. A zero-bias diode is used as a simple direct detection receiver, which is cost-effective compared to a conventional coherent receiver. Moreover, we comprehensively investigate the system performance by applying linear and nonlinear equalization schemes. The experimental results show that Volterra nonlinear filtering can significantly improve the system capacity by around 90%, and transmissions of up to 60 Gbit/s PAM-4 signals over a 3 m wireless link are successfully achieved. The advantageous features of this make it promising for high-speed THz wireless communications.
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| 17. |
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| 18. |
- Wang, Shiwei, et al.
(författare)
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26.8-m THz wireless transmission of probabilistic shaping 16-QAM-OFDM signals
- 2020
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Ingår i: APL Photonics.. - : AIP Publishing. - 2378-0967. ; 5:5
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Tidskriftsartikel (refereegranskat)abstract
- Recently, remarkable efforts have been made in developing wireless communication systems at ultrahigh data rates, with radio frequency (RF) carriers in the millimeter wave (30-300 GHz) and/or in the terahertz (THz, >300 GHz) bands. Converged technologies combining both the electronics and the photonics show great potential to provide feasible solutions with superior performance compared to conventional RF technologies. However, technical challenges remain to be overcome in order to support high data rates with considerably feasible wireless distances for practical applications, particularly in the THz region. In this work, we present an experimental demonstration of a single-channel THz radio-over-fiber (RoF) system operating at 350 GHz, achieving beyond 100 Gbit/s data rate over a 10-km fiber plus a >20-m wireless link, without using any THz amplifiers. This achievement is enabled by using an orthogonal frequency division multiplexing signal with a probabilistic-shaped 16-ary quadrature amplitude modulation format, a pair of highly directive Cassegrain antennas, and advanced digital signal processing techniques. This work pushes the THz RoF technology one step closer to ultrahigh-speed indoor wireless applications and serves as an essential segment of the converged fiber-wireless access networks in the beyond 5G era.
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| 19. |
- Yu, Xianbin, et al.
(författare)
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Multi-dimensional Multiplexed Fiber-Wireless Transmission in the THz Band
- 2022
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Ingår i: Proceedings of the 2022 Conference on Lasers and Electro-Optics Pacific Rim, CLEO/PR 2022. - : Optica Publishing Group.
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Konferensbidrag (refereegranskat)abstract
- We propose and experimentally demonstrate multi-dimensional multiplexed THz photonic wireless communication systems, achieving wireless net data rates of up to 510 Gbit/s and 1.059 Tbit/s in the 350 GHz band.
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| 20. |
- Yu, Xianbin, et al.
(författare)
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Multi-dimensional Multiplexed Fiber-Wireless Transmission in the THz Band
- 2022
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Ingår i: 2022 Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2022 - Proceedings. - : Institute of Electrical and Electronics Engineers (IEEE).
-
Konferensbidrag (refereegranskat)abstract
- We propose and experimentally demonstrate multi-dimensional multiplexed THz photonic wireless communication systems, achieving wireless net data rates of up to 510 Gbit/s and 1.059 Tbit/s in the 350 GHz band.
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| 21. |
- Zhang, Hongqi, et al.
(författare)
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Tbit/s Multi-Dimensional Multiplexing THz-Over-Fiber for 6G Wireless Communication
- 2021
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Ingår i: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8724 .- 1558-2213. ; 39:18, s. 5783-5790
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Tidskriftsartikel (refereegranskat)abstract
- Photonics-aided terahertz (THz) wireless systems have been progressively developed to accommodate the forthcoming wireless communication with extremely high data rates in recent years. However, restrained by the obtainable signal-to-noise ratio (SNR) and the dimensions explored in THz photonic wireless systems, achieving data rates of Tbit/s and beyond is still challenging. In this paper, we present a multi-dimensional multiplexing Tbit/s THz-over-Fiber wireless communication system, by efficiently benefiting from the multiplexing gain in both optical wavelength and space domains. Enabled by a combined routine of an optical frequency comb, a low inter-core crosstalk (IC-XT) multi-core fiber and advanced digital signal processing, a line rate of up to 1176 Gbit/s over a wireless distance of 10 m in the 350 GHz band is experimentally demonstrated without any THz amplifiers, resulting in a net data rate of up to 1059 Gbit/s. To the best of our knowledge, this is the first time that beyond Tbit/s wireless data rate is successfully achieved in the THz region above 300 GHz, making a significant contribution to the development of THz-over-Fiber systems for the sixth generation (6G) wireless communication.
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| 22. |
- Zhang, Lu, et al.
(författare)
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Nonlinearity-aware optoelectronic terahertz discrete multitone signal transmission with a zero-bias diode
- 2020
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Ingår i: Optics Letters. - : The Optical Society. - 0146-9592 .- 1539-4794. ; 45:18, s. 5045-5048
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Tidskriftsartikel (refereegranskat)abstract
- The terahertz band has been recognized as a promising candidate to support future rate-greedy applications such as 6G communications. Optoelectronic terahertz communications are beneficial for the realization of high-speed transmission. In this Letter, we propose and experimentally demonstrate an optoelectronic terahertz transmission system with intensity modulation and direct detection, where a discrete multitone (DMT) waveform with high-order quadrature amplitude modulation (QAM) is used. A zero-bias diode (ZBD) is used in the system as a simple, cost-effective direct detection terahertz receiver. A nonlinearity-aware digital signal reception routine is proposed to mitigate the nonlinear impairments induced by subcarrier-to-subcarrier beating interference from the ZBD. In this experiment, up to a 60 Gbit/s line rate 16QAM-DMT signal is successfully transmitted over a 3 m wireless link in the 310 GHz band, and the mean signal-to-noise ratio is improved by 3 dB with nonlinearity-aware signal processing routine. The advantageous features of such a scheme make it a promising solution for terahertz wireless communications.
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| 23. |
- Niemi, MEK, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 24. |
- Alfakes, Boulos, et al.
(författare)
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Enhanced photoelectrochemical performance of atomic layer deposited Hf-doped ZnO
- 2020
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Ingår i: Surface & Coatings Technology. - : Elsevier BV. - 0257-8972 .- 1879-3347. ; 385
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Tidskriftsartikel (refereegranskat)abstract
- Generation of hydrogen using photoelectrochemical (PEC) water splitting has attracted researchers for the last two decades. Several materials have been utilized as a photoanode in a water splitting cell, including ZnO due to its abundance, low production cost and suitable electronic structure. Most research attempts focused on doping ZnO to tailor its properties for a specific application. In this work, atomic layer deposition (ALD) was used to precisely dope ZnO with hafnium (Hf) in order to enhance its PEC performance. The resultant doped materials showed a significant improvement in PEC efficiency compared to pristine ZnO, which is linked directly to Hf introduction revealed by detailed optical, structural and electrical analyses. The photocurrent obtained in the best performing Hf-doped sample (0.75 wt% Hf) was roughly threefold higher compared to the undoped ZnO. Electrochemical impedance spectroscopy (EIS) and open-circuit potential-decay (OCPD) measurements confirmed suppression in photocarriers' surface recombination in the doped films, which led to a more efficient PEC water oxidation. The enhanced PEC performance of Hf-doped ZnO and effectiveness of the used metal dopant are credited to the synergistic optimization of chemical composition, which enhanced the electrical, structural including morphological, and optical properties of the final material, making Hf-doping an attractive candidate for novel PEC electrodes.
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| 25. |
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