| Popis: |
The distribution of the NLO polarization induced in amorphous polymers by poling is generally nonuniform, especially in those with a high glass transition temperature desirable for stability of the polarization. At high temperature and high poling fields, space-charge effects come into play and make the internal field and polarization nonuniform. As the polarization distribution may affect phase matching, knowledge and control of this distribution is desirable for efficient SHG. We have used a laser-induced-thermal-pulse method to obtain polarization- versus-depth profiles over a wide range of poling variables for the amorphous, strongly coupled paraelectric copolymer of vinylidene cyanide and vinyl acetate with superior intrinsic SHG properties and high glass-transition temperature. The stability of the polarization in the glassy state is also documented. |
