Resonant optical nonlinearity of fullerenes in freehyphen;standing polymethyl methacrylate films

摘要

We have prepared films of polymethyl methacrylate in which fullerenes (a mixture of C60and C70) are uniformly embedded. By performing both degenerate fourhyphen;wave mixing experiments and irradiancehyphen;dependent transmission measurements with nanosecond laser pulses of 608hyphen;nm wavelength, the thirdhyphen;order nonlinear optical susceptibility of these films is determined to be of the order of 10minus;10esu. This susceptibility is dominated by its imaginary part. Excitedhyphen;state absorption is the main mechanism responsible for the observed nonlinear susceptibility.