Beam self-imaging in nonlinear graded-index multimode optical fibers is of interest for many applications, such as implementing a fast saturable absorber mechanism in fiber lasers via multimode interference. We obtain a new exact solution for the nonlinear evolution of first and second order moments of a laser beam of arbitrary transverse shape carried by a graded-index multimode fiber. We have experimentally directly visualized the longitudinal evolution of beam self-imaging by means of femtosecond laser pulse propagation in both the anomalous and the normal dispersion regime of a standard telecom graded-index multimode optical fiber. Light scattering out of the fiber core via visible photo-luminescence emission permits us to directly measure the self-imaging period and the beam dynamics. Spatial shift and splitting of the self-imaging process under the action of self-focusing are also revealed.
Nonlinear beam self-imaging and self-focusing dynamics in a GRIN multimode optical fiber. Theory and experiments / Hansson, Tobias; Tonello, Alessandro; Mansuryan, Tigran; Mangini, Fabio; Zitelli, Mario; Ferraro, Mario; Niang, Alioune; Crescenzi, Rocco; Wabnitz, Stefan; Couderc, Vincent. - In: OPTICS EXPRESS. - ISSN 1094-4087. - 28:16(2020), pp. 24005-24021. [10.1364/OE.398531]
Nonlinear beam self-imaging and self-focusing dynamics in a GRIN multimode optical fiber. Theory and experiments
Mangini, Fabio;Zitelli, Mario;Ferraro, Mario;Crescenzi, Rocco;Wabnitz, Stefan;
2020
Abstract
Beam self-imaging in nonlinear graded-index multimode optical fibers is of interest for many applications, such as implementing a fast saturable absorber mechanism in fiber lasers via multimode interference. We obtain a new exact solution for the nonlinear evolution of first and second order moments of a laser beam of arbitrary transverse shape carried by a graded-index multimode fiber. We have experimentally directly visualized the longitudinal evolution of beam self-imaging by means of femtosecond laser pulse propagation in both the anomalous and the normal dispersion regime of a standard telecom graded-index multimode optical fiber. Light scattering out of the fiber core via visible photo-luminescence emission permits us to directly measure the self-imaging period and the beam dynamics. Spatial shift and splitting of the self-imaging process under the action of self-focusing are also revealed.File | Dimensione | Formato | |
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