Electronic nonlinear optical behaviour of a grating coupled polymer 4BCMU waveguide

The electronic ?⁽³⁾ nonlinear optical behaviour of blue, thermally evaporated P4BCMU has been investigated at ?=1.064 µm using TM-polarized grating coupled guided-wave techniques. The analysis involves a rigorous treatment of the electromagnetic fields in the vicinity of the grating and a theoretically generated fit to the nonlinear reflectivity response which yields both the real and the imaginary components of ?⁽³⁾ in a single experiment. The values obtained are Re(?⁽³⁾)=-(1.3±0.4)x10^-10 esu and Im(?⁽³⁾)=(2.1±0.6) x 10^-10 esu. Considerable care has been taken to establish the electronic origin of the effect. The results show a significant increase in two-photon absorption relative to red spun films of the same polymer at 1.064 µm. © 1994.