The dispersion of an efficient secondary chromophore into in situ crosslinked nonlinear optical polymer networks is described. The secondary chromophore leads to both enhanced electro-optical(-1) at 1.31 mu m) (EO) activity (> 260 pm V and alignment stability at 85 degrees C. Analysis of the EO properties shows exceptional poling efficiency of these binary systems at high chromophore loading levels, in contrast to experimental results obtained from single-chromophore polymers.