Photoinduced layer alignment control in ferroelectric liquid crystal with N*–C* phase transition doped with photochromic dye

Abstract

Photoinduced layer alignment control has been proposed in an azo-dye-doped ferroelectric liquid crystal with a chiral nematic (N*)–chiral smectic C (SmC*) phase sequence. This layer alignment control is based on the N*–SmC* phase transition induced by the photoisomerization of the azo-dye. Trans-cis photoisomerization of the azo-dye upon UV irradiation in the SmC* phase induces the N* phase, and an opposite isomerization process upon sequentially stopping the UV irradiation induces the SmC* phase again. The photoinduced SmC*–N*–SmC* phase transition under an appropriate electric field allows us to control the smectic layer alignment. This photoassisted layer switching can be applied to the fabrication of the designed multidomain structure in electro-optic elements such as display, optical memory, and optical grating.