Abstract

We have performed nonlinear absorption measurements at 532 nm and 1064 nm in solutions of C₆₀/C₇₀ (95%/5%) in CCl₄. Our nonlinear transmittance data at 532 nm agrees with the data reported in Ref. ¹, where optical limiting was attributed to triplet-triplet absorption. Our data is observed to fit very well the expected behavior for two photon absorption at 532 nm. The measured β = 2.44 cm/ GW at a concentration of 0.020 mM. The 1064 nm nonlinear transmittance data fits a three photon rather than a two photon absorption dependence. The measured γ = 0.0347 cm³/GW² at a concentration of 0.31 mM. This indicates a fifth order nonlinearity at 1064 nm, which was also observed in degenerate four wave mixing in a C₆₀ film at comparable irradiances (1-10 GW/cm²).²

© 1992 Optical Society of America