Interaction of light with a NLC-dendrimer system

The interaction of light with a nematic liquid crystal (NLC) doped with dendrimers containing terminal light-absorbing azobenzene fragments and a low-molar-mass dye identical to the fragments was studied in detail. Both the dendrimers and the dye induce orientational nonlinearity in a transparent nematic host. For the fifth-generation dendrimer, the nonlinearity is negative (director is rotated away from the light field direction). For the first-generation dendrimer and the dye, the nonlinearity sign depends on the light propagation direction with respect to the NLC director, light polarisation and external electric field. The results obtained show that complication of the molecular structure of the dopant, i.e. passing from the ‘free’ dye molecule to the first- and fifth-generation dendrimers, results in an increase of the efficiency of the orienting effect of the light.