Parabolic pulse evolution in normally dispersive fiber amplifiers preceding the similariton formation regime

University of Southampton, Southampton, England, United Kingdom
Optics Express (Impact Factor: 3.49). 05/2006; 14(8):3161-70. DOI: 10.1364/OE.14.003161
Source: PubMed


We show analytically and numerically that parabolic pulses and similaritons are not always synonyms and that a self-phase modulation amplification regime can precede the self-similar evolution. The properties of the recompressed pulses after SPM amplification are investigated. We also demonstrate that negatively chirped parabolic pulses can exhibit a spectral recompression during amplification leading to high-power chirp-free parabolic pulses at the amplifier output. (c) 2006 Optical Society of America.

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Available from: Christophe Finot, Sep 15, 2014
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    • "Generation of stable PPs has been the focus of much research activities over past years due to their potential applications in high power lasers and amplifiers [6], [7], Supercontinuum generations [8], and all-optical signal processing and regeneration [9]. Generations of active medium-based PPs have been demonstrated recently [5], [10]. However, the active mediumbased pure PP generation is affected by amplifier spontaneous emission noise and its limited band-width. "
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    ABSTRACT: This paper presents a theoretical design of chalcogenide glass based tapered microstructured optical fiber (MOF) to generate high power parabolic pulses (PPs) at the mid-IR wavelength (~ 2 {\mu}m). We optimize fiber cross-section by the multipole method and studied pulse evolution by well known Symmetrized Split-Step Fourier Method. Our numerical investigation reveals the possibility of highly efficient PP generation within a very short length (~ 18 cm) of this MOF for a Gaussian input pulse of 60 W peak power and FWHM of 3.5 ps. We examined quality of the generated PP by calculating the misfit parameter including the third order dispersion and fiber loss. Further, the effects of variations in input pulse power, pulse width and pulse energy on generated PP were also studied.
    IEEE Journal of Selected Topics in Quantum Electronics 11/2013; 20(5). DOI:10.1109/JSTQE.2014.2307762 · 2.83 Impact Factor
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    • "These so-called " similariton " solutions propagate in a self-similar manner, holding certain relations (scaling) between pulse power, duration, and chirp parameter. While the asymptotic similariton features seem now well understood [1], the physics of the transition to this solution from arbitrary initial pulses has not been fully explored yet (most of the previous attempts to answer this question have focused on an initial parabolic pulse [2]). In this work, we provide a theoretical and experimental description of the adiabatic transition from an arbitrary low-energy initial condition to the asymptotic similariton state. "
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    ABSTRACT: Pulse propagation in an optical fiber amplifier can be described with the nonlinear Schrödinger equation (NLSE) with linear gain. Using a self-similar ansatz and standard amplitude-phase decomposition, we obtain reduced equations for the key pulse parameters (peak amplitude, pulse duration and chirp coefficient) along with a known hydrodynamic-type system of equations for the intensity and phase (see, e.g., [3]). A key physical observation from these equations is that as the peak power grows, the nonlinearity induces a phase change that is proportional to the difference between the intensity profile and a parabolic profile. This in turn reshapes the intensity towards a parabolic form. To illustrate the transition dynamics, we experimentally and numerically analyze an 6-km long Raman fiber amplifier operating at normal dispersion using initial low-energy Gaussian pulses at telecommunication wavelengths. Experimental temporal intensity profiles recorded for various initial peak powers are shown in Fig. 1(a),highlighting the required peak power amplification necessary for a complete transition. Numerical simulations confirm the experimental trends, and in Fig.1(b) an example of the key pulse parameter longitudinal evolutions from both numerical simulations and the reduced model are illustrated, showing excellent agreement.
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    • "Nous constatons alors que les impulsions subissent un élargissement temporel et spectral exponentiel qui est, après une certaine distance de propagation, correctement décrit par la solution asymptotique. Dans le cas d'une dérive de fréquence initiale de pente négative, l'impulsion subit néanmoins avant d'atteindre ce régime asymptotique une étape de compression temporelle et spectrale [4]. Fig. 1 : Dynamique d'impulsions initiales de 6 pJ ayant une largeur temporelle de 80 ps avec différents coefficients de dérive de fréquence linéaire initiale. "
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    ABSTRACT: Nous étudions numériquement l'impact d'une dérive de fréquence initiale ou d'un saut de phase initial sur la dynamique asymptotique d'une impulsion se propageant dans un amplificateur à fibre à dispersion normale. Nous montrons notamment que si l'enveloppe de l'impulsion reste correctement décrite par l'expression analytique d'un similariton parabolique, des structures sombres peuvent néanmoins se superposer à cette enveloppe.
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