Ph. Sung et al., NOVEL THERMALLY STABLE CROSS-LINKED NONLINEAR-OPTICAL SILICA FILMS PREPARED BY A SOL-GEL PROCESS, Chemistry of materials, 10(6), 1998, pp. 1642-1646
To improve the orientational stability of the chromophore induced by a
n electric field in a second-order nonlinear optical polymer, we have
synthesized a thermally stable and crosslinkable azo dye, 4-[(4 onyl]-
4'-[N,N-bis(2-hydroxyethyl)amino]azobenzene. The transparent films wit
h silica as matrix and organic chromophore as cross-linking agent were
then prepared by using a sol-gel process. The resulting films heated
at 200 degrees C under a high-corona field exhibited the nonlinear opt
ical coefficient d(33) = 32 pm/V in Maker-fringe measurement. Long-ter
m stability of second-harmonic coefficients in these films was observe
d even at 160 degrees C.