One- and two-photon induced phase transition behavior of nematic liquid crystals containing bis-styryl benzene as a photoresponsive chromophore

One- and two-photon induced phase transition behavior of low-molecular-weight and polymer liquid crystals (LCs) was observed. When a photochemical reaction of a two-photon absorbing dye was induced in a nematic (N) LC, N-to-isotropic (I) phase transition was induced with high spatial resolution. As a result of the phase transition, the refractive index of the materials was changed by two-photon processes. Furthermore, the I phase induced in the polymer LC was thermally stable and it still appeared after heating above N–I phase transition temperature. The results reported here are the first observation of the photochemical phase transition of the LCs induced by a two-photon process.