The second-order nonlinear optical coefficients d(33) (-2 omega:omega,omega) of polymer films doped with novel azo dyes, which have a perfluoroalkylsulfonyl group as an electron acceptor and an extended pi-electron conjugated system, are determined by second-harmonic generation (SHG) measurements. Thin polycarbonate (PC) film doped with 4-(4-(4-perfluorobutylsulfonylphenylazo) naphthylazo)-N-ethyl-N-hydroxyethylaniline showed a large d(33) value, 67 pm/V, at a wavelength of 1064 nm. The decay of the d(33) values was slow due to the stability of the molecular arrangement in a polymer matrix at high temperature. In addition, a side-chain nonlinear optical polymer with this novel disazo dye is synthesized and the decay of d(33) values is estimated.