Cubic nonlinear optical properties of -conjugated polymers from reflection-mode measurements

We describe experimental studies of cubic nonlinear optical properties performed in reflection mode on thin films of polyaniline. It is shown that pump-probe and degenerate four-wave mixing reflection techniques are sensitive enough to obtain readily detectable nonlinear optical signals from polyaniline with femtosecond pulses at light intensities on the order of 100 GW/cm 2. The results are compared with previous studies indicating that nonlinear coefficients of polyaniline are in the range of |n 2 | = 10 -12 -10 -11 cm 2 /W and that the relaxation of the nonlinear effects involves picosecond range processes.