Temperature dependence of the optical Fréedericksz transition in dyed nematic liquid crystals

We investigated the temperature dependence of the optical Fréedericksz threshold in nematic liquid crystals doped with anthraquinone dyes. In the presence of these dyes, the Fréedericksz threshold is anomalously low and exhibits an unusual temperature dependence. A microscopic model is proposed, according to which the anisotropic orientational distribution and the rotational dynamics of the excited dye molecules play an important role in the observed phenomena.