| 1. |
- Cattani, F., et al.
(författare)
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Effect of self-phase modulation in chirped-pulse-amplification-like schemes
- 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. ; 16:11, s. 1874-1879
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Tidskriftsartikel (refereegranskat)abstract
- A detailed analytical investigation is made of the effect of nonlinear self-phase modulation in chirped-pulse-amplification-like schemes. It is demonstrated that self-phase modulation in the amplifier between the stretcher and the compressor breaks the dispersive sign symmetry of the configuration. This implies that, although self-phase modulation is usually considered a deleterious effect, different situations are possible, depending on the parameter regimes considered. In particular, the influence of self-phase modulation on the low-intensity wings of the compressed pulse may be more or less deleterious, depending on the dispersive sign combination of the stretcher and the compressor; in certain parameter regimes, it may in fact even enhance the pulse compression.
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| 2. |
- Karlsson, Magnus, 1967
(författare)
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Four-wave mixing in fibers with randomly varying zero-dispersion wavelength
- 1998
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Ingår i: Journal of the Optical Society of America B: Optical Physics. - 1520-8540 .- 0740-3224. ; 15:8, s. 2269-2275
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Tidskriftsartikel (refereegranskat)abstract
- The effect of random fluctuations in the zero-dispersion wavelength is considered for fiber four-wave mixing. Theoretical expressions for average parametric gain, phase-conjugation conversion efficiency, and gain bandwidth are obtained and found to be in good agreement with experiments. Possible limitations on the noise figure in phase-sensitive amplifiers based on fiber four-wave mixing are also discussed.
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| 3. |
- Karlsson, Magnus, 1967
(författare)
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Modulational instability in lossy optical fibers
- 1995
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Ingår i: Journal of the Optical Society of America B: Optical Physics. - 1520-8540 .- 0740-3224. ; 12:11, s. 2071-2077
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Tidskriftsartikel (refereegranskat)abstract
- The modulational instability in an optical fiber, with loss taken into account, is analytically investigated. It is demonstrated how the linearized equation for perturbation can be solved exactly in terms of Bessel functions, and qualitative differences from previous analytic approaches are pointed out. Finally, the limits imposed by this instability on optical communication systems are discussed. The use of this theory in system design is examined.
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| 4. |
- 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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| 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)
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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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| 7. |
- Altucci, C, et al.
(författare)
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Influence of atomic density in high-order harmonic generation
- 1996
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Ingår i: Optical Society of America. Journal B: Optical Physics. - 0740-3224. ; 13:1, s. 148-156
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated how high-order harmonics generated in rare gases depend on the atomic density. The peak and the profile of the atomic density in the interaction region were measured as a function of the backing pressure and the distance from the nozzle by a differential interferometry technique, The conversion efficiency for the harmonics in the plateau was found to increase approximately quadratically over the entire range of peak pressures investigated (3-80 mbar). The intensity of the harmonics in the cutoff region, in contrast, increased only until an optimum peak pressure was reached, beyond which it decreased. This optimum peak pressure was found to be dependent on both the laser intensity and the process order. To understand this effect, we have performed extensive propagation calculations of both the fundamental and the harmonic fields, using ionization rates and dipole moments from a tunnel ionization model. We obtained good agreement with the experimental results. The observed effect is attributed to ionization-induced defocusing of the fundamental laser beam, which reduces the peak intensity obtained in the medium and shortens the extent of the plateau. (C) 1996 Optical Society of America
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| 8. |
- Cavalcanti, GH, et al.
(författare)
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Vacuum ultraviolet spectrum of six-times ionized xenon, Xe VII
- 1997
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Ingår i: JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS. - : OPTICAL SOC AMER. - 0740-3224. ; 14:10, s. 2459-2462
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The theta-pinch spectrum of six-times ionized xenon, Xe VII, has been recorded in the vacuum ultraviolet region of 300-1300 Angstrom, and 27 new transitions have been identified as combinations between levels of the 5p2-5p5d and 5s5d-5p5d transition array
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| 9. |
- Dyke, T.R., et al.
(författare)
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Experimental demonstration of data erasure for time-domain optical memories
- 1999
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Ingår i: Optical Society of America. Journal B: Optical Physics. - 0740-3224. ; 16:5, s. 805-811
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Tidskriftsartikel (refereegranskat)abstract
- Data erasure is considered an essential requirement for a practical optical time-domain memory, and it requires that the laser used have very good frequency stability. Such a laser is developed for this work, and data erasure is demonstrated with a sample of YSiO5:Eu3+ for write/rewrite pulse sequences of up to a duration of 100 μs. This is two orders of magnitude longer than had been achieved previously. Phase-sensitive detection is introduced and is shown to be invaluable for monitoring the write, rewrite, and read processes.
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| 10. |
- Elman, U., et al.
(författare)
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Influence of laser phase and frequency fluctuations on photon-echo data erasure
- 1996
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Ingår i: Optical Society of America. Journal B: Optical Physics. - 0740-3224. ; 13:9, s. 1905-1915
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Tidskriftsartikel (refereegranskat)abstract
- Erasure of data stored by use of photon echoes has been investigated as a function of data writing time and data storage time. The results clarify the requirements on laser phase and frequency stability for performing photon-echo data erasure. The analysis of phase and frequency stability of a light source by the photon-echo erasure process is illustrated. A theoretical analysis emphasizing the physical processes that affect the erasure efficiency as well as an extensive discussion of possible error sources are given. Finally, an approach to bit-selective photon-echo data erasure that is insensitive to laser phase and frequency fluctuations is suggested.
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