Bistable switching induced by modulational instability in a normally dispersive all-fibre ring cavity

We study theoretically and experimentally the switching dynamics of an all-fibre cavity with normal dispersion. This system exhibits modulational instability on the lower branch of its bistable response. We show that, due to the interaction with the homogeneous mode generated by the neighbouring limit point bifurcation, the modulational instability induces premature up-switching and, in this way, truncates the bistable cycle. This instability is identified experimentally through the observation of growing spectral sidebands just before up-switching. The results are successfully compared with numerical simulations.