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

Photoinduced layer alignment control has been proposed in an azo-dye-doped ferroelectric liquid crystal with a chiral nematic (N*)-chiral smectic C (S mC*) phase sequence. This layer alignment control is based on the N*-SmC* p hase transition induced by the photoisomerization of the azo-dye. Trans-cis photoisomerization of the azo-dye upon UV irradiation in the SmC* phase in duces 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 u s to control the smectic layer alignment. This photoassisted layer switchin g can be applied to the fabrication of the designed multidomain structure i n electro-optic elements such as display, optical memory, and optical grati ng. (C) 2000 American Institute of Physics. [S0003-6951(00)02010-6].