Nonlinear optical chromophores with good transparency and high thermal stability

In order to improve the transparency and thermal stabilities of nonlinear optical (NLO) chromophores, new materials based on the azo benzene chromophore having 1,3,5-triazine groups were prepared. Their NLO properties were experimentally derived using a two-level model. Compared with corresponding NLO chromophores p-nitroaniline (PNA) and C.I. Disperse Red 1, the newly synthesised chromophores displayed better transparency and higher thermal stability. The reaction of a new NLO chromophore with a dianhydride resulted in polyimide that was converted to a poled polymer which had a d33 value of 69 pm/v, a Tg of 225°C, decomposition temperature of 354°C and an absorption cut-off below 450 mm, indicating its ability for harmonic generation application in the blue and green regions.