A lateral optical equilibrium in waveguide-resonator optical force.

We consider the lateral optical force between a resonator and a waveguide, and study the possibility of an equilibrium that occurs solely from the optical force in such system. We prove analytically that a single-resonance system cannot give such an equilibrium in the resonator-waveguide force. We then show that two-resonance systems can provide such an equilibrium. We provide an intuitive way to predict the existence of an equilibrium, and give numerical examples.