Non-linear optical properties of epoxy-based polymers with covalently attache chromophores and metallic complexes

Non-linearl refraction and absorption in polymer structures based upon diglicidylether of bisphenol A has been studied. The polymers contain organo-metallic complex of nickel(II) NiL(ClO4) 2- or 4-amino-azobenzene as non-linear optically active side groups covalently attached at each monomer unit. The studies have been carried out by polarization technique together with a real time pump and probe technique, dynamic holography and Z-scan. The materials were shown to exhibit fast non-linear response (relaxation time is about 20 ns) together with slow one (relaxation time of the order of tens of hours). This makes it possible to record fast- and long-lived (quasi-stationary) phase holograms. The analysis of possible mechanisms for the polymer refractive index non-linear response in the time range from 10-8 to 105 is presented. In particular, the role of electron polarizability, thermal excitation of the polymer, orientation of the chromophore molecules, and trans-cis isomerization processes are discussed.