  We show, theoretically and experimentally, the existence of a multi-stable
regime in a nonlinear saturable coupler. In spite of its simplicity, we found
that this model shows generic and fundamental properties of extended saturable
lattices. The study of this basic unit becomes crucial to understand
localization mechanisms and dynamical properties of extended discrete nonlinear
saturable systems. We theoretically predict the regions of existence of
intermediate solutions, and experimentally confirm it by observing a
multi-stable propagation regime in a LiNbO3 saturable coupler. This constitutes
the first experimental evidence of the existence of these unstable
symmetry-broken stationary solutions.
