Effect of Ester Moieties in Dye Structures on Photoinduced Reorientation of Dye-Doped Liquid Crystals

The photoinduced reorientation behavior of dye-doped nematic liquid crystals (LCs) was investigated. Thiophene derivatives with ester moieties were newly synthesized as the guest dye molecule. The liquid-crystalline behavior and optical properties of these compounds were evaluated, and the effect of the dye structure on the photoinduced reorientation behavior of the dye-doped LCs was investigated. The photoinduced formation of diffraction rings was observed as a result of the self-phase modulation effect at the intensity of 11 W/cm2, when an Ar+ laser beam at 488 nm was irradiated above the threshold intensity. Comparison of the lowest threshold light intensity for the appearance of the diffraction rings revealed that the thiophene dye with ester moieties directly bound to the terminal thiophene shows a lower threshold intensity than those of any other dyes.