Chaos on a saturable optical dimer

A pair of periodically coupled and forced simple oscillators can exhibit aperiodic behaviors. Here we study the effect of periodic spatial modulations in an optical dimer composed of photorefractive saturable waveguides. The propagation of light along these waveguides as a function of the initial condition exhibits chaotic behaviors. The dynamical behaviors are elucidated based on the adequate representation of the variables, frequency spectra, and Poincaré sections. Homoclinic and heteroclinic entanglements associated with the hyperbolic points that separate the stable equilibria are the origin of the chaotic behavior. The different dynamical regimes have been characterized as a function of light power and initial conditions. Our results open the possibility of using optical saturable dimers in the secure transmission of information.