Sol-gel chemistry for nonlinear optics

摘要

Nonlinear optical materials have been synthesized via the sol-gel route. A chemical control of the reactivity of molecular precursors toward hydrolysis and condensation allows the deposition of transparent thin or thick films. Potassium titanyl phosphate (KTP) can be better synthesized from phosphoester precursors $LB@PO(OH)$-3$MIN@x$/(OR)$-x$/$RB rather than phosphoric acid $LB@PO(OH)$-3$/$RB or phosphate esters $LB@PO(OR)$-3$/$RB@. These precursors lead to crystalline transparent KTP thin films around 600$DGR@C. Organic molecules for nonlinear optics can be embedded into an oxide sol-gel matrix. Second harmonic generation has been obtained after poling with thick films in which organic chromophores are chemically bonded to the oxide backbone via the use of functionalized silicon alkoxide precursors.