Synthesis and characterization of polymers for nonlinear optical applications
Résumé
A difunctional NLO Azo-Dye chromophore has been synthesized and polymerization has been performed with a comonomer bearing a side-chain epoxy group. Deposition of the polymer on glass substrates was performed by spin-coating, resulting in uniform films up to 2 μm thickness. The orientation of the chromophore was performed under a "pin-to-plane" positive corona discharge followed by a heat- treatment in order to obtain reticulation of the films. Molecular orientation has been investigated using UV-Vis. and Raman spectroscopy. Poling of the films results in a decay of absorbance as well as in a blue shift of the spectrum. At the same time, the 1600 cm-1 band disappears from the Raman spectra, indicating orientation of the chromophores. Cross-linking has been studied by FTIR and all-optical poling and showed an improved stability of the electro-optic thin films.