The second-order nonlinear optical properties of four polyureas with large positive birefringence are presented. The temporal stability of the poling-induced orientations at different temperatures were estimated by in-situ second harmonic generation (SHG) measurements. For the polyurea prepared from aliphatic diamines, the optical transparency was down to 300 nm. The most interesting aspect of these polyureas is in their refractive indices : the refractive indices of TE modes before poling are higher than those of TM modes. This indicates that the polymer chains were stretched along the substrate surface. This work represents the first example of an increase of poling-induced refractive indices in TE modes.