The non-linear absorption coefficients of C60 thin films at 633 nm wer
e measured with the absolute measurement and the Z-scan method, respec
tively. Both measurements yield a large non-linear absorption coeffici
ent beta = 4.4 cm W-1 and 8.0 cm W-1. A thermal self-focusing focusing
effect was also observed. The possible mechanisms of the larger non-l
inear absorption were discussed. We predict that C60 thin film may be
a good optical limiter for a continuous wave (cw) laser.