OPTICAL PROPERTIES AND FLUCTUATIONS IN LIQUID CRYSTALS WITH ONE-DIMENSIONAL LARGE-SCALE PERIODICITY

摘要

The Green's function of electromagnetic field and the correlation function of director fluctuations in cholesteric liquid crystals with a pitch being large compared to the wavelength are considered. The wave propagation and the fluctuations spectrum are analyzed in the framework of unique approach based on the modified WKB method. The periodic system is distinguished from an anisotropic medium by a discontinuity of the wave vector surface and a break of the beam vector surface. Trajectories of beams in such a medium are not plane. The forbidden zone corresponds to a capture of beams and formation of a wave channel. The director fluctuations near turn points where the WKB method is not valid are considered.