Synthesis and third-order optical nonlinearity in two-dimensional A-π-D-π-A carbazole-cored chromophores

Novel A-π-D-π-A carbazole-cored chromophores were synthesized and characterized by NMR, IR, UV techniques. The third-order NLO properties of the carbazole chromophores were investigated. The measurements of second-order hyperpolarizabilities were performed using single-beam Z-scan technique with picosecond laser pulses in DMF solutions. Our results indicate that larger second-order hyperpolarizabilities γ can be readily obtained in such carbazole chromophores because of increasing strength of withdrawing group and molecular conjugation length with two aromatic bridges in the two-dimensional conjugated system. Therefore, it is very probable that the increase in the obtained γ values considerably arises from the conjugation path of the delocalized electrons for large third-order nonlinear optical effects.