Abstract

Polymers can exhibit both large and fast nonresonant third-order nonlinearities which rely on π-electron delocalization and conjugation, as well as good physical and chemical properties suitable for the fabrication of nonlinear integrated optics devices. Soluble polymers with strong charge transfer states such asymmetrically substituted 4-dialkylamino-4′-nitro-stilbene (DANS) and 4-dialkylamino-4′-nitro-diphenylbu-tadiene (DAN2) side-groups were originally developed for electro-optic applications because of their large second order nonlinearities and low propagation losses in waveguide form.¹ Using nonlinear grating coupling we found a large value for n₂, the Kerr coefficient. Measurements and analysis of the spectral dispersion of third harmonic generation indicate that the dominant contribution to the nonlinearity is due to the local cascading of second order nonlinearities.²

© 1991 Optical Society of America