A new optomechanical interaction and a model with non-trivial classical dynamics

In traditional cavity optomechanical models, a coupling between the cavity field and mechanical degrees of freedom is a result of dependence of the frequency or the life-time of a cavity mode on mechanical variables. However, optical cavities with degenerate modes may exhibit a different type of optomechanical coupling, which originates from the spatial reconfiguration of the cavity field caused by mechanical motion. Such coupling can, for instance, arise in the case of whispering-gallery-modes in spherical resonators interacting with a polarizable dipole. Here we introduce a model with this previously unexplored type of optomechanical coupling, and as a first step toward understanding the properties of this model we study its classical dynamics in the absence of dissipation and an external pump. We show that the dynamical properties of such a model are characterized by a bifurcation manifested by a loss of stability of a simple equilibrium and a transition to a more complex nonlinear dynamics.