| 1. |
- de Jong, Michel P, et al.
(författare)
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Femtosecond charge transfer in assemblies of discotic liquid crystals
- 2008
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 112:40, s. 15784-15790
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Tidskriftsartikel (refereegranskat)abstract
- The electronic coupling strength within columns of discotic liquid crystals is investigated using core-level resonant photoemission spectroscopy. Coexisting well-ordered and disordered regions are identified in thin films of tetra-alkoxy-substituted phthalocyanines with the aid of near edge X-ray absorption fine structure and photoelectron spectroscopies. These different regions are used to derive a lower limit for the intermolecular charge transfer bandwidth within the framework of the core-hole clock principle. We find average charge transfer times on the order of a few femtoseconds, that is, significantly faster than the C(ls) core-hole lifetime, which indicates a surprisingly strong electronic coupling between the phthalocyanine units as compared to what is expected from the charge transport characteristics of this material. © 2008 American Chemical Society.
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| 2. |
- Kolpakov, S., et al.
(författare)
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Optical rogue waves in coupled fiber Raman lasers
- 2020
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Ingår i: Optics Letters. - : OSA - The Optical Society. - 0146-9592 .- 1539-4794. ; 45:17, s. 4726-4729
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Tidskriftsartikel (refereegranskat)abstract
- For coupled linear cavity-random fiber Raman lasers, for the first time, to the best of our knowledge, we demonstrate a new mechanism of emergence of the random pulses, with the anomalous statistics satisfying optical rogue waves’ criteria experimentally. The rogue waves appear as a result of the coupling of two Raman cascades, namely, a linear cavity laser with a wavelength of 1.55 µm and a random laser with a wavelength nearly 1.67 µm, along with coupling of the orthogonal states of polarization (SOPs). The coherent coupling of SOPs causes localization of the trajectories in the vicinity of these states, whereas polarization instability drives escape taking the form of chaotic oscillations. Antiphase dynamics in two cascades result in the suppression of low amplitude chaotic oscillations and enable the anomalous spikes, satisfying rogue waves criteria.
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| 3. |
- Kolpakov, S., et al.
(författare)
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Polarization dynamics of coupled raman lasers
- 2020
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Ingår i: International Conference on Transparent Optical Networks. - : IEEE Computer Society.
-
Konferensbidrag (refereegranskat)abstract
- We experimentally demonstrated a new mechanism of generation of random pulses with the anomalous statistics (optical rogue waves) in a system of coupled Raman lasers. The pump laser with a linear cavity and wavelength of 1550 nm was coupled to a random laser generating nearby 1670 nm. These rogue waves appeared as a result of the interactions between Raman cascades and a coupling of the orthogonal states of polarization (SOPs). The desynchronization of SOPs caused by polarization instability led to chaotic oscillations. Due to the antiphase dynamics in two cascades, these chaotic oscillations were transformed into anomalous spikes satisfying rogue waves criteria.
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| 4. |
- Leong, Miu Yoong, et al.
(författare)
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BCH Codes for Coherent Star DQAM Systems with Laser Phase Noise
- 2017
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Ingår i: Journal of optical communications. - : Walter de Gruyter. - 0173-4911 .- 2191-6322. ; 38:1, s. 47-56
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Tidskriftsartikel (refereegranskat)abstract
- Coherent optical systems have relatively high laser phase noise, which affects the performance of forward error correction (FEC) codes. In this paper, we propose a method for selecting Bose-Chaudhuri-Hocquenghem (BCH) codes for coherent systems with star-shaped constellations and M-ary differential quadrature amplitude modulation (DQAM). Our method supports constellations of any order M which is a power of 2, and includes differential M-ary phase shift keying as a special case. Our approach is straightforward, requiring only short pre-FEC simulations to parameterize a statistical model, based on which we select codes analytically. It is applicable to pre-FEC bit error rates (BERs) of around 10-3. We evaluate the accuracy of our approach using numerical simulations. For a target post-FEC BER of 10-5, codes selected with our method yield BERs within 2× target. Lastly, we extend our method to systems with interleaving, which enables us to use codes with lower overhead.
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| 5. |
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| 6. |
- van der Valk, Ralf J P, et al.
(författare)
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A novel common variant in DCST2 is associated with length in early life and height in adulthood.
- 2015
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Ingår i: Human molecular genetics. - : Oxford University Press (OUP). - 1460-2083 .- 0964-6906. ; 24:4, s. 1155-68
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Tidskriftsartikel (refereegranskat)abstract
- Common genetic variants have been identified for adult height, but not much is known about the genetics of skeletal growth in early life. To identify common genetic variants that influence fetal skeletal growth, we meta-analyzed 22 genome-wide association studies (Stage 1; N = 28 459). We identified seven independent top single nucleotide polymorphisms (SNPs) (P < 1 × 10(-6)) for birth length, of which three were novel and four were in or near loci known to be associated with adult height (LCORL, PTCH1, GPR126 and HMGA2). The three novel SNPs were followed-up in nine replication studies (Stage 2; N = 11 995), with rs905938 in DC-STAMP domain containing 2 (DCST2) genome-wide significantly associated with birth length in a joint analysis (Stages 1 + 2; β = 0.046, SE = 0.008, P = 2.46 × 10(-8), explained variance = 0.05%). Rs905938 was also associated with infant length (N = 28 228; P = 5.54 × 10(-4)) and adult height (N = 127 513; P = 1.45 × 10(-5)). DCST2 is a DC-STAMP-like protein family member and DC-STAMP is an osteoclast cell-fusion regulator. Polygenic scores based on 180 SNPs previously associated with human adult stature explained 0.13% of variance in birth length. The same SNPs explained 2.95% of the variance of infant length. Of the 180 known adult height loci, 11 were genome-wide significantly associated with infant length (SF3B4, LCORL, SPAG17, C6orf173, PTCH1, GDF5, ZNFX1, HHIP, ACAN, HLA locus and HMGA2). This study highlights that common variation in DCST2 influences variation in early growth and adult height.
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| 7. |
- Adamatzky, Andrew, et al.
(författare)
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East-West paths to unconventional computing
- 2017
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Ingår i: Progress in Biophysics and Molecular Biology. - : Elsevier BV. - 0079-6107 .- 1873-1732. ; 131, s. 469-493
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Forskningsöversikt (refereegranskat)abstract
- Unconventional computing is about breaking boundaries in thinking, acting and computing. Typical topics of this non-typical field include, but are not limited to physics of computation, non-classical logics, new complexity measures, novel hardware, mechanical, chemical and quantum computing. Unconventional computing encourages a new style of thinking while practical applications are obtained from uncovering and exploiting principles and mechanisms of information processing in and functional properties of, physical, chemical and living systems; in particular, efficient algorithms are developed, (almost) optimal architectures are designed and working prototypes of future computing devices are manufactured. This article includes idiosyncratic accounts of ‘unconventional computing’ scientists reflecting on their personal experiences, what attracted them to the field, their inspirations and discoveries.
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| 8. |
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| 9. |
- El-Taher, A., et al.
(författare)
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Noise characterization and transmission evaluation of unrepeated Raman amplified DP-16QAM link
- 2015
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Ingår i: Optical Fiber Communication Conference, OFC 2015. - Washington, D.C. : The Optical Society. - 9781557529374
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Konferensbidrag (refereegranskat)abstract
- Impairments characterization and performance evaluation of Raman amplified unrepeated DP-16QAM transmissions are conducted. Experimental results indicate that small gain in forward direction enhance the system signal-to-noise ratio for longer reach without introducing noticeable penalty.
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| 10. |
- Jacobsen, G., et al.
(författare)
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Phase noise influence in coherent optical DnPSK systems with DSP based dispersion compensation
- 2014
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Ingår i: Journal of optical communications. - : Walter de Gruyter GmbH. - 0173-4911 .- 2191-6322. ; 35:1, s. 57-61
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Tidskriftsartikel (refereegranskat)abstract
- We present a comparative study of the influence of dispersion induced phase noise for n-level PSK systems. From the analysis, we conclude that the phase noise influence for classical homodyne/heterodyne PSK systems is entirely determined by the modulation complexity (expressed in terms of constellation diagram) and the analogue demodulation format. On the other hand, the use of digital signal processing (DSP) in homodyne/intradyne systems renders a fiber length dependence originating from the generation of equalization enhanced phase noise. For future high capacity systems, high constellations must be used in order to lower the symbol rate to practically manageable speeds, and this fact puts severe requirements to the signal and local oscillator (LO) linewidths. Our results for the bit-error-rate (BER) floor caused by the phase noise influence in the case of QPSK, 16PSK and 64PSK systems outline tolerance limitations for the LO performance: 5 MHz linewidth (at 3-dB level) for 100 Gbit/s QPSK; 1 MHz for 400 Gbit/s QPSK; 0.1 MHz for 400 Gbit/s 16PSK and 1 Tbit/s 64PSK systems. This defines design constrains for the phase noise impact in distributed-feed-back (DFB) or distributed-Bragg-reflector (DBR) semiconductor lasers, that would allow moving the system capacity from 100 Gbit/s system capacity to 400 Gbit/s in 3 years (1 Tbit/s in 5 years). It is imperative at the same time to increase the analogue to digital conversion (ADC) speed such that the single quadrature symbol rate goes from today's 25 GS/s to 100 GS/s (using two samples per symbol).
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| 11. |
- Jaskorzynska, Bozena, et al.
(författare)
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Nonlinear upconversion-rate in Er-doped fibers
- 2001
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Ingår i: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 99:1, s. 147-153
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Tidskriftsartikel (refereegranskat)abstract
- Energy transfer between excited rare-earth ions has been widely used for realizing upconversion lasers and also recognized as a gain limiting factor in high-concentration Er-doped amplifiers. The energy transfer leads to upconversion of the excitation which for randomly distributed (not clustered) ions is called homogeneous upconversion. It was commonly assumed that the rate of homogeneous upconversion is a linear function of the population inversion N-2. However, recently published Monte Carlo simulations predict that the homogeneous upconversion rate is a nonlinear function of N-2 and that it, moreover, depends on the pump and signals rates. In this paper we review some of our experimental results confirming those predictions. We also propose a statistical, analytical model describing the observed homogeneous upconversion behavior in Er-doped fibers.
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| 12. |
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| 13. |
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| 14. |
- Khoptyar, D., et al.
(författare)
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Homogeneous upconversion in Er-doped fibers under steady state excitation : analytical model and its Monte Carlo verification
- 2005
-
Ingår i: Journal of the Optical Society of America. B, Optical physics. - 0740-3224 .- 1520-8540. ; 22:3, s. 582-590
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Tidskriftsartikel (refereegranskat)abstract
- We present an extension to our earlier proposed statistical model for studying migration-assisted homogeneous upconversion in erbium-doped fibers. The extension takes into account minimum proximity distance between erbium ions randomly distributed in the host material and the nonuniformity of the excitation distribution among them. We derive a transcendental equation for the population inversion and find the dependence of the upconversion rate on the population inversion and the pump power for the entire range of feasible Er concentrations. We verify the validity and accuracy of the model by means of time-resolved Monte Carlo simulations.
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| 15. |
- Khoptyar, D., et al.
(författare)
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Upconversion assisted decay of population inversion in Er-doped silica after delta-pulse excitation
- 2005
-
Ingår i: IEEE Journal of Quantum Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9197 .- 1558-1713. ; 41:2, s. 205-212
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Tidskriftsartikel (refereegranskat)abstract
- We investigate homogeneous upconversion (HUC) assisted decay of the population inversion in Er-doped silica after delta-pulse excitations by means of Monte Carlo simulations. We derive an analytic expression for this decay when energy migration among Er is negligible and show that it is essentially an extension of the Forster-type donor-acceptor quenching decay for the case when donor and acceptor ions are the same species. We compare HUC during the decay to HUC while pumping CW and show that they considerably differ at the low and moderate Er concentrations. Based on Monte Carlo (MC) simulations, we construct a neuristic approximation to the HUC assisted decay, which makes our MC results readily available for the future experimental and theoretical studies and provides simple means for determination of HUC parameters by fitting to experimental data.
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| 16. |
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| 17. |
- Leong, Miu Yoong, et al.
(författare)
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Receiver sensitivity in optical and microwave, heterodyne and homodyne systems
- 2014
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Ingår i: Journal of optical communications. - : Walter de Gruyter GmbH. - 0173-4911 .- 2191-6322. ; 35:3, s. 221-229
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we analyze the sensitivities of coherent optical receivers and microwave receivers. We derive theoretical limits of signal-to-noise ratio and bit error rate. By applying a generic approach to a broad range of receivers, we can compare their performance directly. Other publications have considered some of these receivers. However, their diverse nature obscures the big picture. Using our results as a unifying platform, previous publications can be compared and discrepancies between them identified.
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| 18. |
- Popov, Sergei, et al.
(författare)
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Impact of dielectric permittivity of a substrate on the THz scattering enhanced due to near-field effect
- 2010
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Ingår i: 2010 Asia Communications and Photonics Conference and Exhibition, ACP 2010. - : IEEE. - 9781424471119 ; , s. 330-331
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Konferensbidrag (refereegranskat)abstract
- Enhanced scattering of the THz radiation caused by the interaction of near field component with plasmons in a substrate material results in sub-wavelength resolution within THz range. Variation of dielectric permittivity of organic materials placed on a metal substrate can improve contrast of the image obtained with such a technique.
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| 19. |
- Popov, Sergei, et al.
(författare)
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Mode stability in robust microcavity solid-state dye laser
- 2008
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Ingår i: Frontiers in Optics - Microcavities and Lasers (2008). - : Optical Society of America. - 9781557528612
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Konferensbidrag (refereegranskat)abstract
- Polymeric microcavity dye laser modeled with finite element method demonstrates excellent tolerance against geometrical distortions of the cavity. Mode wavelengths remain stable with two types of potential impairments might occur during the manufacturing process.
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| 20. |
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| 21. |
- Popov, Sergei, et al.
(författare)
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The impact of pump polarization on the polarization dependence of the Raman gain due to the breaking of a fibre's circular symmetry
- 2004
-
Ingår i: Journal of Optics. A, Pure and applied optics. - : IOP Publishing. - 1464-4258 .- 1741-3567. ; 6:3, s. S72-S76
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Tidskriftsartikel (refereegranskat)abstract
- For many practical applications, the polarization dependence of the Raman gain (Raman PDG) is considered as a drawback. Most approaches used to reduce the PDG are based on depolarization or scrambling of the pump source polarization. We report on an experimentally observed effect and describe a method for reducing the Raman PDG by means of polarization control with a fully polarized pump source. The method makes it possible to maintain high efficiency of the Raman gain. The absence of circular symmetry (on average) in non-polarization maintaining fibres allows one to find a certain polarization state of the pump to minimize the Raman PDG. The observed phenomenon is inherently related to polarization mode dispersion which always exists in optical fibres.
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| 22. |
- Rosa, P., et al.
(författare)
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Unrepeatered 240-km 64-QAM transmission using distributed raman amplification over SMF fiber
- 2020
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Ingår i: Applied Sciences. - : MDPI AG. - 2076-3417. ; 10:4
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Tidskriftsartikel (refereegranskat)abstract
- We present a theoretical and experimental investigation of unrepeatered transmission over standard single-mode fiber (SMF-28) using several schemes of distributed Raman amplification, including first, second, and dual order. In order to further extend the transmission distance, we utilize advanced bidirectional higher-order ultra-long Raman fiber laser-based amplification, where we use fiber Bragg gratings (FBGs) to reflect Stokes-shifted light from the secondary pumps. Our work demonstrates the possibility of transmission up to 240-km span length with a total span loss of 52.7 dB. Here, we use a 28-Gbaud signal using a 64-quadrature amplitude modulation (QAM) modulation format. Our results highlight the contribution of nonlinear compensation using digital back propagation in a digital signal processor (DSP) code at the receiver. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
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| 23. |
- Sergeyev, S., et al.
(författare)
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Fiber Raman amplifiers with suppressed polarization impairments
- 2009
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Ingår i: 2009 Conference on Lasers and Electro-Optics and 2009 Conference on Quantum Electronics and Laser Science Conference, CLEO/QELS 2009. - Washington, D.C. : OSA. - 9781557528698 ; , s. 3103-3104
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Konferensbidrag (refereegranskat)abstract
- By using two-section fiber where the first section has no spin and the second one is periodically spun, we demonstrate reduced polarization dependent gain and polarization mode dispersion in a distributed fiber Raman amplifier.
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| 24. |
- Sergeyev, S., et al.
(författare)
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Influence of the short-range coordination order of erbium ions on excitation migration and upconversion in multicomponent glasses
- 2005
-
Ingår i: Optics Letters. - 0146-9592 .- 1539-4794. ; 30:11, s. 1258-1260
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Tidskriftsartikel (refereegranskat)abstract
- Applying a pair-correlation function of erbium ions that is known from x-ray absorption fine structure spectroscopy, we develop a new statistical model of migration-assisted upconversion in erbium-doped glasses. The results of modeling show that short-range coordination order of erbium ions contributes to the upconversion rate for both low and high population inversion. In addition, we report the methods of suppression of the short-range order of erbium ions in multicomponent glasses.
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| 25. |
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| 26. |
- Sergeyev, S., et al.
(författare)
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Modeling polarization-dependent gain in fiber Raman amplifiers with randomly varying birefringence
- 2006
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 262:1, s. 114-119
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Tidskriftsartikel (refereegranskat)abstract
- We report a new stochastic model for studying the polarization-dependent gain in Raman fiber amplifiers with randomly varying birefringence as a function of the pump state of polarization and the polarization mode dispersion parameter. Our theoretical results agree with the previously obtained experimental data.
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| 27. |
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| 28. |
- Sergeyev, S., et al.
(författare)
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Pump-to-signal intensity noise transfer as the mechanism of self-pulsing in erbium doped fiber laser
- 2009
-
Ingår i: OFC. - Washington, D.C. : IEEE. - 9781424426065 ; , s. 2879-2881
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Konferensbidrag (refereegranskat)abstract
- We report experimental and theoretical characterization of self-pulsing in high concentration erbium doped fiber laser which is free from erbium clusters. Unlike previous models of self-pulsing which account for pair-induced quenching (PIQ) on the clustered erbium ions, new model includes statistical nature of the excitation migration and upconversion, and resonance-like pump-to-signal intensity noise transfer. The obtained results are in a good agreement with the experimental data.
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| 29. |
- Sergeyev, S., et al.
(författare)
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Spun Aber Raman amplifiers with reduced polarization impairments
- 2008
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Ingår i: Optics Express. - 1094-4087. ; 16:19, s. 14380-14389
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Tidskriftsartikel (refereegranskat)abstract
- We report a novel vector model of Raman amplification in a fiber with randomly varying birefringence and unidirectional spin profile. Applying the model, we demonstrate for the first time simultaneous mitigation of polarization mode dispersion and polarization dependence of the Raman gain.
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| 30. |
- Sergeyev, S., et al.
(författare)
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Spun fiber Raman amplifiers
- 2008
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Ingår i: Frontiers in Optics (FiO) 2008. - : Optical Society of America. - 9781557528612
-
Konferensbidrag (refereegranskat)abstract
- We report a novel vector model of Raman amplification in a fiber with randomly varying birefringence and unidirectional spin profile. Based on this model, we demonstrate for the first time simultaneous mitigation of polarization mode dispersion and polarization dependent gain.
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| 31. |
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| 32. |
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| 33. |
- Sergeyev, S., et al.
(författare)
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Upconversion and migration in erbium-doped silica waveguides in the continuous-wave excitation switch-off regime
- 2002
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 65:23
-
Tidskriftsartikel (refereegranskat)abstract
- Based on an approach for averaging solution of rate equations over possible ensemble configurations, we derive integral equation for population inversion taking into account nonlinear homogeneous upconversion and migration in Er3+-doped silica waveguides for the case of 1480-nm CW excitation switch-off (CWES) regime. Because of pump for CWES is off, only migration tends to refill the holes in excitation distribution caused by upconversion. Thus the upconversion is weaker than that for the CW operation, except for t=0 and t-->infinity, upconversion.
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| 34. |
- Sergeyev, S., et al.
(författare)
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Upconversion assisted auto-oscillations in erbium doped fiber laser
- 2009
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Ingår i: 2009 Conference on Lasers and Electro-Optics and 2009 Conference on Quantum Electronics and Laser Science Conference, CLEO/QELS 2009. - Washington, D.C. : OSA. - 9781557528698 ; , s. 5225267-
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Konferensbidrag (refereegranskat)abstract
- A new model of auto-oscillations in high concentration erbium doped fiber laser has been developed with accounting for statistical nature of the excitation migration and upconversion, as well as resonance-like pump-to-signal intensity noise transfer.
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| 35. |
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| 36. |
- Sergeyev, S. V., et al.
(författare)
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A new PMD measurement technique
- 2007
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Ingår i: International Conference on Lasers, Applications, and Technologies 2007. - : SPIE - International Society for Optical Engineering. - 0819468894 - 9780819468895 ; , s. 67310S-
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Konferensbidrag (refereegranskat)abstract
- We report measurements of beat and birefringence correlation lengths, and the PMD value on a long single mode fiber. The proposed technique is based on the analysis of maximum and minimum polarization dependent gain in a fiber Raman amplifier. Results are consistent with a standard technique based on differential group delay measurements.
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| 37. |
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| 38. |
- Sergeyev, S. V., et al.
(författare)
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Characterization of randomly varying birefringence in long single mode fibers
- 2008
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Konferensbidrag (refereegranskat)abstract
- We report an application of new vector model of fiber Raman amplifier to charac-terize randomly varying birefringence in long single mode fiber. We find that analysis of the polarization dependent Raman gain can be used for the measurements of beat and birefrin-gence correlation lengths and the polarization mode dispersion value. The results for averaged PMD parameters are consistent with the values obtained by means of the Jones matrix eigenanalysis method.
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| 39. |
- Sergeyev, S. V., et al.
(författare)
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Statistical model for energy-transfer-induced up-conversion in Er3+-doped glasses
- 2000
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 62:23, s. 15628-15633
-
Tidskriftsartikel (refereegranskat)abstract
- We present a statistical model for studying excitation upconversion and migration caused by energy transfer between Er3+ ions in a glass matrix. Assuming a statistically uniform distribution of ions in the matrix we propose an approach for averaging the solution of the rate equations over possible ensemble configurations. The model provides a transcendental equation for the population inversion and the up-conversion rate in the steady-state case, and an integral equation for delta -pulse excitation. Analytical expressions are given for the asymptotes at small and large population inversions, as well as at the initial time fur the dynamic case. The model explains well the experimentally observed nonlinear dependence of the up-conversion rate versus population inversion, and the enhancement of the up-conversion caused by the migration.
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| 40. |
- Sergeyev, S.V, et al.
(författare)
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Two-section fiber optic Raman polarizer for high-speed transmission systems
- 2011
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Ingår i: 2011 13TH INTERNATIONAL CONFERENCE ON TRANSPARENT OPTICAL NETWORKS (ICTON).
-
Konferensbidrag (refereegranskat)abstract
- We report on a theoretical study of polarization impairments in periodically spun fiber Raman amplifiers. Based on the Stochastic Generator approach we have derived equations for polarization dependent gain and mean-square gain fluctuations. We show that periodically spun fiber can work as a Raman polarizer but it suffers from increased polarization dependent gain and gain fluctuations. Unlike this, application of a depolarizer can result in suppression of polarization dependent gain and gain fluctuations. We demonstrate that it is possible to design a new fiber Raman polarizer by combining a short fiber without spin and properly chosen parameters and a long periodically spun fiber. This polarizer provides almost the same polarization pulling for all input signal states of polarization and so have very small polarization dependent gain. The obtained results can be used in high-speed fiber optic communication for design of quasi-isotropic spatially and spectrally transparent media with increased Raman gain.
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| 41. |
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| 42. |
- Xu, Tianhua, et al.
(författare)
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Analysis of carrier phase extraction methods in 112-Gbit/s NRZ-PDM-QPSK coherent transmission system
- 2012
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Ingår i: 2012 Asia Communications And Photonics Conference (ACP). - Washington, D.C. : IEEE. - 9781467362740 ; , s. AS1C.2-
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Konferensbidrag (refereegranskat)abstract
- We present a comparative analysis on three carrier phase extraction approaches, including a one-tap normalized least mean square method, a block-average method, and a Viterbi-Viterbi method, in coherent transmission system considering equalization enhanced phase noise.
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| 43. |
- Xu, Tianhua, et al.
(författare)
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Analysis of chromatic dispersion compensation and carrier phase recovery in long-haul optical transmission system influenced by equalization enhanced phase noise
- 2017
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Ingår i: Optik (Stuttgart). - : Elsevier GmbH. - 0030-4026 .- 1618-1336. ; 138, s. 494-508
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Tidskriftsartikel (refereegranskat)abstract
- The performance of long-haul coherent optical fiber transmission system is significantly affected by the equalization enhanced phase noise (EEPN), due to the interaction between the electronic dispersion compensation (EDC) and the laser phase noise. In this paper, we present a comprehensive study on different chromatic dispersion (CD) compensation and carrier phase recovery (CPR) approaches, in the n-level phase shift keying (n-PSK) and the n-level quadrature amplitude modulation (n-QAM) coherent optical transmission systems, considering the impacts of EEPN. Four CD compensation methods are considered: the time-domain equalization (TDE), the frequency-domain equalization (FDE), the least mean square (LMS) adaptive equalization are applied for EDC, and the dispersion compensating fiber (DCF) is employed for optical dispersion compensation (ODC). Meanwhile, three carrier phase recovery methods are also involved: a one-tap normalized least mean square (NLMS) algorithm, a block-wise average (BWA) algorithm, and a Viterbi-Viterbi (VV) algorithm. Numerical simulations have been carried out in a 28-Gbaud dual-polarization quadrature phase shift keying (DP-QPSK) coherent transmission system, and the results indicate that the origin of EEPN depends on the choice of chromatic dispersion compensation methods, and the effects of EEPN also behave moderately different in accordance to different carrier phase recovery scenarios.
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