title: Resonant modes in cholesteric liquid crystals with a gaussian pitch profile.
abstract: In this paper, we investigate the spectral properties of a cholesteric film presenting a pitch profile with a gaussian deformation. Using the Berreman 4 × 4 matrix formalism, we numerically obtain the transmission spectrum at normal and oblique light incidence as a function of width and the position of the deformation. Our results reveal that a pair of resonant modes emerges inside the main stop band of the transmission spectrum as the width of the deformation becomes comparable to the helical pitch length. The mechanism behind the emergence of the resonant modes is discussed. The case of a pitch profile with multiple gaussian deformations is also analyzed. At this configuration, a crossover from single to multiple band-gap pattern can be observed in the transmission spectrum, depending on the deformation parameters.
authors.affiliation: Instituto de Física, Universidade Federal de Alagoas, 57072-970 Maceió, AL, Brazil.
authors.forename: R R
authors.initials: RR
authors.lastname: da Silva
authors.forename: F M
authors.initials: FM
authors.lastname: Zanetti
authors.forename: I N
authors.initials: IN
authors.lastname: de Oliveira