Low power nonlinear optical response of C60 and C70 fullerene solutions

Solutions of C60 and C70 exhibit a large third‐order nonlinear response, even when investigated with low‐power visible lasers. The remarkably large nonlinearity observed is attributed to a combined effect of thermally induced nonlinear refractive index changes and simultaneous nonlinear absorption. Fullerenes have the potential for applications in all‐optical devices if they retain the same properties as in solution when dispersed in a transparent polymer matrix.