Chaotic optical fibre for power amplifier

Summary form only. In the geometrical limit, the transverse section of a fibre can be seen as a 2-dimensional billiard. In a circular fibre, ray trajectories are regular. Whereas introducing a straight cut will induce complex dynamics of rays, which lead to a chaotic behaviour. In power amplifier systems with optical fibre, double cladding doped fibres are used. The signal in the single-mode doped core is amplified by the way of a pump injected in the pump multimode core. The pump is absorbed along the propagation by the doped core, so that the whole power in the multimode core decays.