Measurement on the third-order optical nonlinearity of C70 and its poly-aminonitrile derivative by using the femtosecond optical Kerr effect

We have measured the second-order hyperpolarizability γ for C70 and its poly-aminonitrile derivative by using the femtosecond optical Kerr effect at 810 nm. The result showed that C70 exhibited a low optical nonlinearity. For the derivative C70–poly-aminonitrile a magnitude as high as 1.6×10−32 esu was measured for the second-order hyperpolarizability. The origin of this extreme enhancement of the nonlinearity of fullerene was assigned to the formation of a charge-transfer complex.