Nonlinear optical response of fullerenes

A critical review of nonlinear optical properties of fullerenes is presented. We explore structure property relationships for optical nonlinearities of these unusual pi electron systems from two complementary angles: (i) to explore the possibility of obtaining structural information from nonlinear optical experiments and (ii) to assess the potential of fullerenes, fullerites and their derivatives for the practical nonlinear optical devices. In particular we show that substituted fullerenes form an interesting class of molecules for nonlinear optics. We will also show that third harmonic generation of circularly polarised light in the solid fullerites should yield some information on the intermolecular interactions in these solids. We critically examine the various calculations indicating that the screening of the optical fields due to electron-electron interaction may reduce the optical susceptibilities of these molecules by a large factor and suggest experiments that may clarify the issue.