Dispersion of quadratic nonlinearity of polarized films of chromophore-containing polyimides in the range of resonance absorption

Detailed investigations of the second harmonic generation of a series of new chromophore-containing polyimides in the range of their absorption bands are performed. Polymer films with thickness of 100–400 nm were spin-cast on glass substrates and corona poled. For the samples, the quadratic nonlinearity coefficients are determined from the intensity of the second harmonic generation signal. Fundamental wavelength was varied from 800 to 1400 nm. The quadratic nonlinear coefficient d33 of these materials with respect to the reference sample of quartz crystal are estimated. Maximum values of the second harmonic generation coefficient, d33, are 25–50 pm/V.