Improved Temporal Stability of the Second-Order Nonlinear Optical Effect in a Sol−Gel Matrix Bearing an Active Chromophore

A second-order nonlinear optical (NLO) chromophore (disperse red 1) was reacted with (3-isocyanatopropyl)triethoxysilane to form a functionalized silicon alkoxide precursor (SGDR1). To improve the temporal stability of the second-order NLO effect, we employed a thermal cross-link between the organic side groups themselves. (3-Glycidoxypropyl)trimethoxysilane was mixed with SGDR1 in tetrahydrofuran (SGDR1/GPTS). We compared the temporal stability of the poled samples with SGDR1 and SGDR1/GPTS. We investigated second-order NLO properties of sol−gel films by virtue of second harmonic generation (SHG) and linear electrooptic (E/O) coefficient measurements for the purpose. We achieved much improvement in the temporal stability of second-order NLO effect at high temperature with the heterogeneous films.