We theoretically analyse the dynamics of Brillouin scattering in Perot-Fabr
y fibre cavities. An original approach to the stability analysis of the ste
ady state allows us to define the instability domain and to locate chaotic
behaviours up to now attributed to Kerr effect. Numerical investigations gi
ve evidence of a Newhouse-Ruelle-Takens route to chaos, associated with the
increase in the number of cavity modes under the gain curve. (C) 1999 Else
vier Science B.V. All rights reserved.