Degenerate four-wave mixing in endohedral metallofullerenes and optical limiting of C-60 derivatives and higher fullerenes

We report two separate studies of the nonlinear optical properties of unique fullerene materials. Degenerate four-wave mixing measurements of the endohedral metallofullerene Er-2@C-82 at 1064 nm show that the third order susceptibility is increased by more than two orders of magnitude relative to the empty cage fullerenes as a result of the metal-to-cage charge transfer. Optical limiting studies of C-60 derivatives and higher fullerenes (i.e. C-76 and C-84) in the 680 to 880 nn spectral region demonstrate that these materials are strong reverse saturable absorbers at wavelengths where C-60 itself is transparent. The tremendous variety of available fullerene-derived structures provides important opportunities for optimization of nonlinear optical responses.