Processible polyetherimide-based polymers that display nonlinear optical (NLO) activity are reported to have been synthesized by the Mitsunobu reaction, in which the polyimide structure is synthesized directly in a single step from a diimide and a diol, without a high-temperature thermal imidization step. The resulting polymers, with pendant-incorporated tricyanovinyl azobenzene chromophores, showed very large second-order NLO activity with good temporal and thermal stability-in one case no decay of the signal was observed up to 125 degrees C.