ELECTRONIC NONLINEAR-OPTICAL BEHAVIOR OF A GRATING-COUPLED POLYMER 4BCMU WAVE-GUIDE

The electronic chi((3)) nonlinear optical behaviour of blue, thermally evaporated P4BCMU has been investigated at lambda = 1.064 mu m using TM-polarized grating coupled guided-wave techniques. The analysis invo lves a rigorous treatment of the electromagnetic fields in the vicinit y of the grating and a theoretically generated fit to the nonlinear re flectivity response which yields both the rear and the imaginary compo nents of chi((3)) in a single experiment. The values obtained are Re(c hi((3))) = -1.3 +/- 0.4) x 10(-10) esu and Im(chi((3))) = (2.1 +/- 0.6 ) x 10(-10) esu. Considerable care has been taken to establish the ele ctronic origin of the effect. The results show a significant increase in two-photon absorption relative to red spun films of the same polyme r at 1.064 mu m.