Stilbazolium derivatives are very attractive optical materials for photonic
s and biophotonics applications because a large number of these derivatives
are available and they can exhibit large third-order nonlinear coefficient
s and rapid responses. To quantitatively characterize their third-order non
linear coefficients and the temporal responses of their third-order nonline
ar process, we have performed degenerate four-wave mixing and Z-scan experi
ments on four stilbazolium derivatives with different electron donors using
40 ps laser pulses at 532 nm. The gamma values for three of the compounds
are on the order of 10(-31) esu. These high values arise from electronic pr
ocesses and are associated with both nonlinear absorption and nonlinear ref
raction. The relative contributions from nonlinear absorption and nonlinear
refraction are dependent on the chemical structure and linear absorption o
f the stilbazolium derivative. (C) 2001 American Institute of Physics.