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| 4. |
- Anderson, D., et al.
(författare)
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A variational approach to spherical aberrations in the thermal-wave model for beam dynamics in charged particle accelerators
- 1998
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Ingår i: Physica Scripta. - : Institute of Physics Publishing. - 0031-8949 .- 1402-4896. ; 58:6, s. 608-612
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Tidskriftsartikel (refereegranskat)abstract
- A direct variational approach involving trial functions and Ritz optimization, which has previously been found very useful in nonlinear optics, is applied to analyze the effects of spherical aberrations on the focusing properties of charged particle beams in particle colliders. As compared to conventional perturbation theory, the variational approach provides a simple and physically clear analysis. Explicit expressions are given for the transverse particle beam density, the spot size, and the luminosity reduction factor at the interaction point, in good agreement with the perturbative results.
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| 5. |
- Dimitrevski, K., et al.
(författare)
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Analysis of stable self-trapping of laser beams in cubic-quintic nonlinear media
- 1998
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Ingår i: Physics Letters A. - : Elsevier. - 0375-9601 .- 1873-2429. ; 248:5-6, s. 369-376
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Tidskriftsartikel (refereegranskat)abstract
- A numerical and analytical analysis of two-dimensional laser beam propagation in cubic-quintic nonlinear optical media demonstrates the existence of stable stationary radially symmetric modes. By means of a variational method, involving super-Gaussian trial functions and Ritz optimization, approximate stationary solutions are obtained, showing very good agreement with numerical results, even in the strongly non-linear, almost saturated, regime. The stability of the stationary modes are verified by analytical analysis and by direct numerical simulations.
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| 6. |
- Malomed, B. A., et al.
(författare)
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Decay of parametric solitons in a lossy medium with quadratic nonlinearity
- 1996
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Ingår i: Pure and Applied Optics (Print edition) (United Kingdom). - : IOP Publishing. - 0963-9659. ; 5:6, s. 941-946
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Tidskriftsartikel (refereegranskat)abstract
- An investigation is made into the evolution of two-wave solitons in a second-haimonic-generation system under the action of weak dissipation. Using the balance equation for the soliton energy and a previously developed variational approximation for its shape, a general evolutional equation is derived for the soliton parameters. The equation is solved explicitly for the asymptotic stage of the evolution
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| 7. |
- Quiroga-Teixeiro, M. L., et al.
(författare)
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Compression of optical solitons by conversion of nonlinear modes
- 1995
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Ingår i: Journal of the Optical Society of America. B, Optical physics. - 0740-3224 .- 1520-8540. ; 12:6, s. 1110-1116
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Tidskriftsartikel (refereegranskat)abstract
- One can transform an optical pulse containing higher-order soliton modes and/or radiation modes into a compressed almost ideal single-soliton pulse by passing it through an initial adaptive fiber of suitably chosen length and dispersion. Analytical approximations, in good agreement with numerical simulations, are found for the optimal values of the length and the dispersion of the adaptive fiber. The technique is applied to the case of nonadiabatically amplified soliton pulses, for which the transformation is shown to result in efficiently compressed soliton pulses.
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| 8. |
- Quiroga-Teixeiro, M. L., et al.
(författare)
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Compression of optical solitons by conversion of nonlinear modes
- 1998
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- One can transform an optical pulse containing higher-order soliton modes and/or radiation modes into a compressed almost ideal single-soliton pulse by passing it through an initial adaptive fiber of suitably chosen length and dispersion. Analytical approximations, in good agreement with numerical simulations, are found for the optimal values of the length and the dispersion of the adaptive fiber. The technique is applied to the case of nonadiabatically amplified soliton pulses, for which the transformation is shown to result in efficiently compressed soliton pulses.
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| 9. |
- Quiroga-Teixeiro, M. L., et al.
(författare)
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Efficient soliton compression by fast adiabatic amplification
- 1998
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- It is shown that a properly tailored, rapidly increasing gain along the distance of propagation in a monomode fiber can provide fast but still adiabatic soliton amplification and therefore high-quality one-soliton compression for fiber lengths even shorter than the characteristic dispersive length. With the variational approach an explicit expression is given for the required variation of the inhomogeneous gain, and its validity is demonstrated by comparison with direct numerical simulations that include the calculation of the pure soliton component. It is also shown by analytical and numerical perturbation analysis that the compression scheme is stable with respect to small deviations from the ideal soliton form and gain variation. Finally, it is demonstrated that efficient soliton compression can also be obtained by cascading of instantaneous optical amplifiers in an intermediate fiber with higher dispersion, where nonlinear mode conversion preserves the soliton character of the amplified pulse. The practical implementation of these compressor schemes is discussed.
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| 10. |
- Anders, Berntson, et al.
(författare)
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Analysis of coherent and incoherent interactions of amplitude shifted solitons in optical fibres
- 1995
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Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 52:5, s. 544-553
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Tidskriftsartikel (refereegranskat)abstract
- Nonlinear interaction between pulses can severely reduce the bit-rate of an optical communication system. One way of reducing this interaction is amplitude shifting of consequtive pulses. In the present work a detailed analytical and numerical investigation is made of the coherent and incoherent interactions between two soliton pulses of unequal amplitudes. For the case of coherent interaction the obtained expressions for the pulse parameters in terms of initial phase and amplitude differences give a clear and explicit prediction of the reduction of the interaction strength for unequal soliton amplitudes. A comparison with numerical simulation results shows good agreement. For the case of incoherent soliton interaction it is found that the dependence of the interaction strength on the amplitude difference is weak.
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