Abstract

Recent degenerate-four wave mixing (DFWM) studies, performed on C₆₀ [1] and phthalocyanines (Pc) [2] at 1064 nm have shown that these materials possess large optical nonlinearities. The highly delocalized π-electron system within these materials is believed to contribute significantly to the observed nonlinear optical response. In addition, it has been shown in the case of the phthalocyanines that the introduction or modification of low lying electronic states by metal substitution can enhance the optical nonlinearity. There is also evidence that optical pumping to long-lived excited states [2] contributes significantly to the nonlinear response in some of the phthalocyanines. Two photon excitation of these electronic states may also occur. It is the purpose of this paper to investigate the contribution that optical pumping and nonlinear absorption make to the nonlinear response of the material.

© 1992 Optical Society of America