In-situ pyroelectrical study of the polarization dynamics in nonlinear optical polymers and physico-chemical investigation of photo-induced degradation

The photo-isomerization of azo-chromophores in a nonlinear optical side-chain polymer permits the orientation of the dipoles under an applied electric field even well below the glass-transition temperature of the polymer. As the dipoles become orientable only within the penetration depth of the pump light, the technique is especially suitable for the preparation of poling patterns across the thickness of the polymer. Pyroelectrical investigations allow for an in-situ examination of the photo-induced poling process and for an analysis of the resulting nonuniform dipole-orientation patterns. For long-time exposures to the short-wavelength pump light, a photo-induced degradation of the chromophore molecules (photo-bleaching) is observed, which is analyzed by pyroelectrical (thermal) analysis, optical techniques and X-ray photoelectron spectroscopy.