Optically Nonlinear Materials via Sol-Gel Processing

The sol-gel process was used to fabricate optically nonlinear thin films. Organic nonlinear chromophores were incorporated directly into the crosslinked silica network by polymerization of a chromophore containing organosilane, N-[3-(Triethoxysilyl)propyl]-2,4-Dinitrophenylamine. The films were cast by spin coating and the chromophores were oriented by corona-onset poling at temperatures above the glass transition temperature of the polymer. Second harmonic generation coefficients were measured using quartz as a reference and orientational order was studied by spectroscopic absorption measurements. The glass transition temperature of the polymer was controlled by copolymerization of the trifunctional organosilane with the tetrafunctional monomers tetraethoxy silane (TEOS) or tetramethoxy silane (TMOS).