| 1. |
- 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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| 2. |
- 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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| 3. |
- 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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| 4. |
- Quiroga-Teixeiro, M. L., et al.
(författare)
-
Compression of optical solitons by conversion of nonlinear modes
- 1998
-
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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| 5. |
- Quiroga-Teixeiro, M. L., et al.
(författare)
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Efficient soliton compression by fast adiabatic amplification
- 1996
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Ingår i: Journal of the Optical Society of America. B, Optical physics. - : Optical Soc of America. - 0740-3224 .- 1520-8540. ; 13:4, s. 687-692
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Tidskriftsartikel (refereegranskat)abstract
- This paper shows the possibility of obtaining fast, but still adiabatic, amplification of soliton pulses by using a rapidly increasing distributed amplification with scale lengths comparable with the characteristic dispersion length. Explicit expressions for the required distribution of this gain and the variation of the pulse width are given, and theoretical predictions have been verified by numerical simulations. The practical implementation of the compression scheme should be possible by using an active fiber with a doping proportional to the required gain distribution. A study was also made of how efficient compression of solitons can be obtained.
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| 6. |
- Quiroga-Teixeiro, M. L., et al.
(författare)
-
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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| 7. |
- Anders, Berntson, et al.
(författare)
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Self-phase modulation in dispersion compensated optical fibre transmission systems
- 1996
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Ingår i: Optics Communications. - : Elsevier. - 0030-4018 .- 1873-0310. ; 130:1-3, s. 153-162
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Tidskriftsartikel (refereegranskat)abstract
- An analysis is made of the influence of self-phase modulation on optical fibre communication systems where the chromatic dispersion is compensated for by a dispersion compensation fibre. In particular we derive a simple and useful expression for the optimal fibre length in the presence of nonlinearities.
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| 8. |
- Quiroga-Teixeiro, M. L., et al.
(författare)
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Internal dynamics of nonlinear beams in their ground states : Short- and long-lived excitation
- 1999
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Ingår i: Journal of the Optical Society of America. B, Optical physics. - : Optical Society of America (OSA). - 0740-3224 .- 1520-8540. ; 16:10, s. 1697-1704
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated the dynamics of optical beams in a cubic (focusing)-quintic (defocusing) nonlinear medium. In particular, we have found that strong beams can show long-lived elliptical oscillations, whereas in other cases, i.e., for weak beams or cylindrical oscillations, the dynamics decay quickly. This finding explains the observed higher efficiency in the fusion of two strong beams. We have also investigated, numerically and analytically, the robustness of the beams to an initial phase chirp.
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