Strong optical force induced by morphology-dependent resonances.

We consider the resonant optical force acting on a pair of transparent microspheres by the excitation of morphology-dependent resonance (MDR). The bonding and antibonding modes of the MDR correspond to strong attraction and repulsion, respectively. The dependence of the force on separation and the role of absorption are discussed. At resonance, the force can be enhanced by orders of magnitude such that it will dominate other relevant forces. We found that a stable binding configuration can be induced by the resonant optical force.