We describe and analyze an all-optical method to measure both the magnitude and the phase of each (complex) element of the χ(3) tensor that determines degenerate four-wave mixing in a thin isotropic film on a thick substrate. We use the method to characterize the χ(3) tensor of a 10-μm C60 film (on a CaF2 substrate) for 110-fs pulses at 768 nm. Using a fused-quartz plate as the nonlinear standard, we find the two independent Maker–Terhune elements of χ(3) to have magnitudes |c1221(−ω, ω, ω, −ω)| = (0.44±0.03) × 10−12 esu and |c1122(−ω, ω, ω, −ω)| = (0.50±0.03) × 10−12 esu and phase angles φ1221 and φ1122, whose magnitudes are 145° ± 17° and 139° ± 10°.
© 1997 Optical Society of America
[Optical Society of America ]
F. P. Strohkendl, L. R. Dalton, R. W. Hellwarth, H. W. Sarkas, and Z. H. Kafafi, "Phase-mismatched degenerate four-wave mixing: complex third-order susceptibility tensor elements of C60 at 768 nm," J. Opt. Soc. Am. B 14, 92-98 (1997)