Z-scan study of optical nonlinearities in two fullerene derivatives

The third-order nonlinear optical properties of two fullerene derivatives under picosecond laser excitation have been investigated by Z-scan technique. The experimental results reveal that all the derivatives have very large nonlinear absorption coefficient under 532 nm pulses excitation and great third-order nonlinear refraction index under 1064 nm pulses excitation. The molecular second hyperpolarizabilities have been obtained from the experimental results.