Aromatic polyureas: a new class of nonlinear optical polymer with large second-harmonic generation

The second-order nonlinear optical properties of aromatic polyureas are reported. From Maker fringe measurements, the nonlinear d₃₃ coefficient of poled polyurea films with and without pendant chromophores was found to be 20*10^-9 esu and 12*10^-9 esu, respectively, at 1.064 mu m. Aromatic polyurea having no pendant chromophores shows a cutoff wavelength of transmission at 307 nm which is the first example of organic NLO materials to be optically transparent at such low wavelengths.