Effect of thermal treatment on the nonlinear optical response and stability of hybrid inorganic-organic films

Hybrid inorganic-organic second-order nonlinear optical (NLO) materials have been obtained through hydrolysis and co-condensation between tetraethyl silicate (TEOS), Vinyltriethoxysilane (VTES) and an alkoxysilane dye (ICTES-DR1). The hybrid materials showed a thermal stability up to 306 °C in thermogravimetric analysis (TGA) thermograms and no visible glass transition temperature (T_g) was observed in the range 50-200 °C in differential scanning calorimetry (DSC) thermograms. The poling profiles of the hybrid films were investigated by using the in situ second harmonic generation (SHG) measurement. The thermal stability of the second order NLO properties of the poled films were also investigated by the in situ SHG intensity probing. It has been shown that the NLO response and its thermal stability were strongly dependent on the thermal pretreatment of the films.