Chaotic oscillations of coupled nanobeam cavities with tailored optomechanical potentials

We reveal novel features of nonlinear optomechanical interactions in coupled suspended nanocavities that are driven by two detuned laser frequencies. Such driving enables simultaneous excitation of odd and even optical supermodes, which induce gradient forces of opposite signs, and the competition between these forces enables the realization of optomechanical potentials with large barriers and narrow wells. These types of potentials were suggested for precise displacement control, or “spectral bonding,” in the static regime. However we find that self-induced oscillations appear even at the deep global potential minima when the mechanical damping rate is below a certain threshold, including a new regime of chaotic switching between mechanical deformations of opposite signs.