OFF-RESONANT NONLINEAR OPTICAL-PROPERTIES OF C60 STUDIED BY DEGENERATE 4-WAVE-MIXING

Pure C60 was deposited on optical substrates in vacuo and spectroscopically characterized. A small linear absorption coefficient-alpha = 6 cm-1 was measured at 1.064-mu-m. Time-resolved degenerate four-wave mixing experiments were conducted on films of pure C60 using a 35 ps Nd: YAG laser at 1.064-mu-m. The third-order optical susceptibility chi(xxxx)(3) of C60, derived from its phase conjugate signal. is 7 X 10(-12) esu. The nonlinear optical temporal response was largely laser-pulse limited. Evidence for a fifth-order contribution to the nonlinear optical response was observed at high laser intensities.