The orientational distribution function of a poled, doped polymer film under stress is measured using polarized second-harmonic generation. The four interface nonlinear boundary conditions are solved, and both the magnitude of the second-order susceptibility and the ratio of the tensor components of the second-order susceptibility, X(2)113/X(2)333 (≡α), are shown to vary with poling field and stress. Further, the sign of the order parameter ratio, ‹P3›/‹P1›, as measured directly by polarized second-harmonic generation of these materials, shows that the materials fall into a regime of order unlike other material classes such as Langmuir—Blodgett films and liquid crystals. For a onedimensional dopant molecule, the order parameters ‹P1›, ‹P2›, ‹P3›, and ‹P4› can be estimated. Materials processed in this way are shown to result in a range of tensor ratios of α = 0.33 with a film under no stress to α = 0.7 with a film under moderate stress.
© 1989 Optical Society of America
M. G. Kuzyk, K. D. Singer, H. E. Zahn, and L. A. King, "Second-order nonlinear-optical tensor properties of poled films under stress," J. Opt. Soc. Am. B 6, 742-752 (1989)