Permanent dipole moments induced stability and group index switching in a three-level molecule

In this paper, the effect of permanent dipole moments on optical bistability of weak probe light in a unidirectional ring cavity with three-level molecule is investigated. It is found that the intensity threshold of optical bistability (OB) and optical multistability (OM) can be controlled by quantum coherence induced by permanent dipole moments. Also, it is shown that switching from OB to OM and lasing without population inversion can be occurred by this coherence under different conditions.