Uniguided and unicoupled resonances in photonic crystal microcavity with a chiral layer

We show that the effect of voltage-induced transparency of a photonic crystal microcavity with a chiral liquid crystal layer is caused by a pair of counter-propagating unidirectionally guided (UGR) and unidirectionally coupled (UCR) resonances. By definition, the UGR is a resonant mode that features single-side outgoing radiation pattern. In contrast to the UGR, the UCR is coupled with the outgoing waves on both sides of the microcavity but, nonetheless, exhibits only a single-sided coupling with incident waves. The results obtained by the rigorous scattering matrix method are explained in the framework of the temporal-coupled mode theory. The scattering spectra in the vicinity of the UGR and the UCR are described theoretically.