Selective infiltration of a photonic crystal fiber with cholesteric liquid crystal

Photonic crystal fibers (PCFs) are fibers with periodically distributed air holes parallel to the fiber core, and located in the cladding region; these holes can be infiltrated with liquids or gases. The passive properties of the PCFs can be enhanced by filling these holes with materials having active optic properties like liquid crystals (LCs).
In this case the selective infiltration of photonic crystal fibers has been made with chiral liquid crystals, named Cholestric Liquid Crystals (CLC). Cholesteric (or chiral nematic) liquid crystal resembles nematic liquid crystal in all physical properties except that the molecules tend to arrange themselves in a helical structure with the helical axis perpendicular to the director. The helical structure leads to a selective wavelength reflection and circular polarization. The length over which the LC director rotates 2π is defined as helical pitch, which indicates the twist extent of LC molecules.