Propagation of an externally focused or defocused Gaussian beam in a cubically nonlinear material is studied analytically and experimentally. The theoretical analysis is applied to determine the sign and magnitude of n2 for a material by means of a single-beam experiment with a finite nonlinear sample within which propagational diffraction cannot be neglected. Experimental results for a solution of chlorophyll in ethanol are reported. Based on available theory, an average n2 can be defined for a nonlinearity of thermal origin, and this value is found to be in good agreement with experimental results. Finally, the theoretical analysis and the experimental results of a double-beam experiment performed to determine the sign and magnitude of n2 are also presented.
© 1991 Optical Society of America
Original Manuscript: April 19, 1990
Revised Manuscript: October 16, 1990
Manuscript Accepted: January 15, 1991
Published: May 1, 1991
P. P. Banerjee, R. M. Misra, and M. Maghraoui, "Theoretical and experimental studies of propagation of beams through a finite sample of a cubically nonlinear material," J. Opt. Soc. Am. B 8, 1072-1080 (1991)