A novel Y-type polyurethane 7 containing 1-(2,4-dioxyethoxy)phenyl-2-{5-(1,2,2-tricyanovinyl)-2-thiophenyl)}ethenyl groups as nonlinear optical (NLO)-chromophores, which are components of the polymer backbones, was prepared. Polyurethane 7 is soluble in common organic solvents such as DMF and DMSO. It showed a thermal stability up to 280 degrees C in TGA thermogram and the T(g) value obtained from DSC thermogram was around 163 degrees C. The second harmonic generation (SHG) coefficient (d(33)) of poled polymer film at 1560 nm fundamental wavelength was around 3.72 x 10(-9) esu. The dipole alignment exhibited a thermal stability up to near Tg, and there was no SHG decay below 150 degrees C due to the partial main-chain character of the polymer structure, which is acceptable for nonlinear optical device applications.