Regular modes of a mixed dynamical based optical fiber

A multimode optical fiber with a truncated transverse cross section acts as a powerful versatile support to investigate the wave features of complex ray dynamics. In this paper, we concentrate on the case of a geometry inducing a mixed dynamics. We highlight the properties of regular modes associated to stable periodic orbits such as an enhanced intensity localization and report unexpected attributes such as the statistics of the Inverse Participation Ratio that present features analogous to those of Anderson localized modes. Our study is supported by both numerical and experimental results.Comment: 12 pages, 13 figure

Ray dispersion strongly modified by a periodic index segmentation

International audienceThe purpose of this article is to analyze the impact of an index segmentation on the ray dispersion in the geometrical approach. The presented study re- veals that a periodic index segmentation of the waveguide along with a trans- verse gaussian index variation exhibits complex ray dynamics that strongly modify ray dispersion properties

Selective amplification of scars in a chaotic optical fiber

In this letter we propose an original mechanism to select scar modes through coherent gain amplification in a multimode D-shaped fiber. More precisely, we numerically demonstrate how scar modes can be amplified by positioning a gain region in the vicinity of specific points of a short periodic orbit known to give rise to scar modes

Optical Scar in a chaotic fibre

We propose to use a multimode optical fiber with a D-shaped cross section as a privileged system to image wavefunctions of a chaotic system. Scar modes are in particular the sub ject of our investigations. We study their imprints on the statistics of intensity and we show how the introduction of a localized gain region in the fiber is used to perform a selective excitation of scar modes.Comment: 13 page

Du "speckle" aux "scars" (une expérience de chaos ondulatoire dans une fibre optique)

Comment caractériser la dynamique d'une onde dans un domaine fermé? Dans la limite géométrique, elle évolue suivant les trajectoires de rayons. Dans cette limite, dès que la géométrie du domaine s'écarte d'une forme simple, les trajectoires exhibent une dynamique chaotique, c'est-à-dire irrégulière et extrêmement sensible aux conditions initiales. Les manifestations ondulatoires de cette dynamique géométrique complexe constituent le chaos ondulatoire, qui se manifeste quelle que soit la nature de l'onde. Il existe deux types d'études expérimentales : celles utilisant les ondes acoustiques (vibration de plaques, par exemple) ou celles employant les ondes électromagnétiques (essentiellement dans les cavités micro-ondes).NICE-BU Sciences (060882101) / SudocLANNION-ENSSAT (221132206) / SudocSudocFranceF

Numerical modeling of pump absorption in coiled and twisted double-clad fibers

International audienceWe report the analysis of multimode pump absorption in double-clad rare-earth-doped fibers under realistic bending conditions. The finite-element beam-propagation method is used for the analysis. The fiber bending is approximated by the transformation of the refractive index profile of the fiber. Double-clad fibers of hexagonal, circular and stadium-like cross-sections are studied as examples. In addition, the double-clad waveguide structure of a two-fiber bundle is investigated. Simulations show that the bending effects cannot be neglected in double-clad fiber multimode pump propagation analysis and optimization. The reported rigorous numerical model opens new way to design double-clad fibers and to optimize the pump absorption efficiency. We show that high pump-absorption efficiency better than the ideal (ergodic) limit, can be achieved by simultaneous coiling and twisting of the double-clad fiber. Index Terms—double-clad optical fibers, optical pumping, fiber lasers, fiber amplifiers, finite element method, beam propagation metho

Complex behaviour of a ray in a periodically segmented waveguide

International audienc

Complex behavior of ray in gaussian index profile periodicaly segmented waveguide

International audienceIn this article, we present a numerical analysis concerning ray propagation in a multimode periodic segmented waveguide with a gaussian index segment profile. We show that this simple waveguide configuration exhibits a complex ray dynamics that can be regular or chaotic depending on the initial conditions

Chaos ondulatoire en optique guidée (amplificateur fibré double-gaine pour la génération de modes "Scar")

NICE-BU Sciences (060882101) / SudocSudocFranceF