Widely tunable optical filter with variable bandwidth based on spatially distributed cholesteric liquid crystal

Abstract

A widely tunable optical filter was designed and demonstrated by configuring two spatially distributed cholesteric liquid crystals (LCs) in a reflection mode, in which the incident light was first reflected by one cholesteric LC and then by the other. The spatially distributed cholesteric LCs were fabricated by injecting four cholesteric LC mixtures with different chiral concentration into the same LC cell one by one, in which the spectral position of the reflection band is spatially changed from blue to red color from one side to the other side. Using this method, a tunable optical filter with the ability of tuning the central wavelength from ∼ 480 to ∼ 613 nm and FWHM from ∼ 10 to ∼ 80 nm was successfully demonstrated.