Photo-induced in-plane alignments of liquid crystal molecules on alternate self-assembled ultrathin films containing azo-dye and evaluation by the attenuated total reflection measurement

A liquid crystal (LC) cell with alternate self-assembled films containing azobenzene dye as aligning layers was fabricated and photo-induced in-plane alignments of nematic LC molecules, 5CB, have been investigated in the cell using the attenuated total reflection (ATR) method. The ATR properties due to excitations of surface plasmon polaritons (SPP) were observed in the LC cell and sensitively changed with irradiation of linearly polarized visible light to the LC cell. The experimental results corresponded well with the calculated shifts at different alignment states. It was evaluated that the LC molecules within the penetration length of the SPP (about 130 nm) were aligned perpendicular to the polarized direction of the irradiation light, and that the tilt angle was almost 0 degree.