Orders of magnitude enhancement of mode splitting by plasmonic intracavity resonance

we report on significant mode splitting in plasmonic resonators induced by intracavity resonance. In contrast to traditional dielectric resonators where only picometer range of splitting was achieved, splitting over several hundred nanometers can be obtained without using ultrahigh quality resonators. We show that by appropriately choosing the coupling length, minute reflection is sufficient to establish intracavity resonance, which effectively lifts the degeneracy of the counterpropagating modes in the resonator. The mode splitting provides two self-referenced channels enabling simultaneous monitoring of the position and the polarizability of nano-scatterers in the resonator.