Large and Fast Resonant Third-Order Optical Nonlinearities of Silicon 2,3-Naphthalocyanine Bi (trihexylsilyloxide)

Third-order optical nonlinearities of silicon 2,3-naphthalocyanine bis(trihexylsilyloxide) (SiNc) were measured by femtosecond degenerate four-wave mixing technique under resonant conditions. The time dependence of the signals indicates that the electronic response dominates the mechanism. The electronic molecular hyperpolarizability γ_e of SiNc was determined to be as high as 2×10^-28 esu, which is the largest value reported so far to our knowledge. The electronic third-order susceptibility for a pure SiNc film has been measured to be 4×10^-7esu. The large nonlinear susceptibility was discussed in terms of J-type molecular arrangement.