| 1. |
- Johansson, Magnus, et al.
(författare)
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Strongly localized moving discrete dissipative breather-solitons in Kerr nonlinear media supported by intrinsic gain
- 2014
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Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - : American Physical Society. - 1539-3755 .- 1550-2376. ; 89:4, s. 042912-1-042912-9
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the mobility of nonlinear localized modes in a generalized discrete Ginzburg-Landau-type model, describing a one-dimensional waveguide array in an active Kerr medium with intrinsic, saturable gain and damping. It is shown that exponentially localized, traveling discrete dissipative breather-solitons may exist as stable attractors supported only by intrinsic properties of the medium, i.e., in the absence of any external field or symmetry-breaking perturbations. Through an interplay by the gain and damping effects, the moving soliton may overcome the Peierls-Nabarro barrier, present in the corresponding conservative system, by self-induced time-periodic oscillations of its power (norm) and energy (Hamiltonian), yielding exponential decays to zero with different rates in the forward and backward directions. In certain parameter windows, bistability appears between fast modes with small oscillations and slower, large-oscillation modes. The velocities and the oscillation periods are typically related by lattice commensurability and exhibit period-doubling bifurcations to chaotically walking modes under parameter variations. If the model is augmented by intersite Kerr nonlinearity, thereby reducing the Peierls-Nabarro barrier of the conservative system, the existence regime formoving solitons increases considerably, and a richer scenario appears including Hopf bifurcations to incommensurately moving solutions and phase-locking intervals. Stable moving breathers also survive in the presence of weak disorder.
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| 2. |
- Kotlyar, Oleksandr, 1982-, et al.
(författare)
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Combining nonlinear Fourier transform and neural network-based processing in optical communications
- 2020
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Ingår i: Optics Letters. - : Optical Society of America. - 0146-9592 .- 1539-4794. ; 45:13, s. 3462-3465
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Tidskriftsartikel (refereegranskat)abstract
- We propose a method to improve the performance of the nonlinear Fourier transform (NFT)-based optical transmission system by applying the neural network post-processing of the nonlinear spectrum at the receiver. We demonstrate through numerical modeling about one order of magnitude bit error rate improvement and compare this method with machine learning processing based on the classification of the received symbols. The proposed approach also offers a way to improve numerical accuracy of the inverse NFT; therefore, it can find a range of applications beyond optical communications.
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| 3. |
- Kotlyar, Oleksandr, 1982-, et al.
(författare)
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Convolutional long short-term memory neural network equalizer for nonlinear Fourier transform-based optical transmission systems
- 2021
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Ingår i: Optics Express. - : Optical Society of America. - 1094-4087. ; 29:7, s. 11254-11267
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Tidskriftsartikel (refereegranskat)abstract
- We evaluate improvement in the performance of the optical transmission systems operating with the continuous nonlinear Fourier spectrum by the artificial neural network equalisers installed at the receiver end. We propose here a novel equaliser designs based on bidirectional long short-term memory (BLSTM) gated recurrent neural network and compare their performance with the equaliser based on several fully connected layers. The proposed approach accounts for the correlations between different nonlinear spectral components. The application of BLSTM equaliser leads to a 16x improvement in terms of bit-error rate (BER) compared to the non-equalised case. The proposed equaliser makes it possible to reach the data rate of 170 Gbit/s for one polarisation conventional nonlinear Fourier transform (NFT) based system at 1000 km distance. We show that our new BLSTM equalisers significantly outperform the previously proposed scheme based on a feed-forward fully connected neural network. Moreover, we demonstrate that by adding a 1D convolutional layer for the data pre-processing before BLSTM recurrent layers, we can further enhance the performance of the BLSTM equaliser, reaching 23x BER improvement for the 170 Gbit/s system over 1000 km, staying below the 7% forward error correction hard decision threshold (HD-FEC).
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| 4. |
- Prilepsky, Jaroslaw E., et al.
(författare)
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Discrete solitons in coupled active lasing cavities
- 2012
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Ingår i: Optics Letters. - : Optical Society of America. - 0146-9592 .- 1539-4794. ; 37:22, s. 4600-4602
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Tidskriftsartikel (refereegranskat)abstract
- We examine the existence and stability of discrete spatial solitons in coupled nonlinear lasing cavities (waveguide resonators), addressing the case of active defocusing media, where the gain exceeds damping in the low-amplitude limit. A new family of stable localized structures is found: these are bright and gray cavity solitons representing the connections between homogeneous and inhomogeneous states. Solitons of this type can be controlled by discrete diffraction and are stable when the bistability of homogenous states is absent.
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| 5. |
- Prilepsky, Jaroslaw E., et al.
(författare)
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Magnetic polarons in one-dimensional antiferromagnetic chains
- 2006
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Ingår i: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 74:13, s. 132404-1-132404-4
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Tidskriftsartikel (refereegranskat)abstract
- We study magnetic polarons in antiferromagnetic chains by using the one-dimensional Anderson-Hasegawa double-exchange discrete model, and find analytically different families of magnetic polaron compactons. To study stability and nontrivial dynamics of the self-trapped magnetic polarons, we generalize the Anderson-Hasegawa model to allow for a finite spin of the lattice, and investigate different types of stationary states with collinear and canted spin structure, revealing the existence of stable nonmobile collinear solutions as well as stable mobile magnetic polarons having a canted structure.
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