Investigation of the thickness mode in surface stabilized ferroelectric liquid crystal cells

Dielectric properties of surface stabilized ferroelectric liquid crystal (SSFLC) cells have been investigated both experimentally and theoretically. The thickness mode is found to consist of two relaxation processes. A decomposition of an analytical solution of the complex dielectric permittivity epsilon(omega) in terms of these processes is given. The experimental results show agreement with theory and lead to the conclusion that the thickness mode can be separated into two processes. It has been found that the ratio of the dielectric strengths for the two processes depends on the cell thickness, and that the ratio of their frequencies is approximately equal to 10. The lower frequency process is assigned to the relaxation within the bulk and the higher frequency process is assigned to the fluctuations of molecules at the two surfaces of the cell. The latter process is seen only in thicker cells for the reason that anchoring at surfaces predominantly controls the behaviour of thinner cells.