Simulating the Brillouin response of arbitrary optical fibres with a finite element method

Abstract

Stimulated Brillouin scattering (SBS) is an important nonlinear optical phenomenon that has been gainfully exploited in many important applications/devices such as slow light generation, Brillouin amplifiers/lasers, and distributed sensing. On the other hand, it is a highly undesirable effect in telecoms applications and in fibre-based devices like parametric amplifiers and fibre lasers. Thus, significant research efforts have been focussed on designing optical fibres with tailored acousto-optic interactions in order to enhance/mitigate their SBS characteristics, which necessitates evaluating their Brillouin gain spectrum (BGS). Various theoretical and numerical techniques for calculating BGS have been reported in recent years, though the applicability of most of these are limited to fibres with radial symmetry and/or weak acoustic guiding properties. In this paper, for the first time to the best of our knowledge, we employ a commercial finite-element method (FEM) solver to calculate the optical and acoustic modes of arbitrary longitudinally invariant fibres and thus determine their BGS. The method, a derivation of the one presented in [1], can be applied to solid fibres with arbitrary refractive index profiles, as well as to microstructured optical fibres (MOFs). Comparisons with reported simulations and with experimental results confirm the accuracy of our implementation.

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Identifiers

ORCID for F. Poletti: orcid.org/0000-0002-1000-3083

ORCID for D.J. Richardson: orcid.org/0000-0002-7751-1058

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