Electric field dependence of optical dispersion process in short pitch ferroelectric liquid crystal

Abstract The short pitch ferroelectric liquid crystal is also called as deformed helix ferroelectric liquid crystal (DHFLC) due to its property of deformation of helical structure by weak field. The DHFLC material has been studied for the analysis of optical diffraction process by varying the incidence and transmission angles. The applied direct current (DC) field has shown the blocking of dispersed light at various oblique angles of incidence due to the unwinding of helical structure. This confirms the fixed helical pitch unwinding model of DHFLC structure. On the other hand, the application of same DC field has also shown the enhancement in the direct transmission confirming the dispersed light at oblique angle which is realigned to the direct light direction. The application of alternating current (AC) field exhibited the tunability of dispersed transmission as a function of frequency of applied field due to the winding and unwinding process of helical structure. The phenomenon of dispersion in transmission mode due to Bragg diffraction phenomenon is significant for non display application of DHFLCs such as phase grating.