Effect of introducing multiple chiral defects on the optical properties of cholesteric liquid crystals

The optical characteristics of cholesteric liquid crystal (ChLC) with multiple defect layers where pitch lengths were modified have been investigated. The transmission spectrum of such multi-defect ChLCs was simulated using the transfer matrix method. A transmission band appeared in the photonic band-gap (PBG) of the ChLC. The PBG displayed a shift as the periodicity of the defect sites was decreased. Finite difference time domain simulations have been carried out to investigate the electromagnetic field distributions within the medium. Obtained results showed that coupling between the modes confined in the defect layers lead to the formation of the defect band in the PBG.