Incoherent optical second harmonic (SH) generation, or hyper-Rayleigh scattering (HRS), is used to study the structure and properties of Gd/C<sub>18</sub>H<sub>36</sub>O<sub>2</sub> multilayer Langmuir–Blodgett (LB) films. SH reflection spectra (in combination with linear absorption spectra), HRS indicatrices, thickness dependence, and wave polarization diagrams are measured for <i>s</i>-polarized fundamental radiation. The SH radiation is entirely diffuse but predominantly <i>s</i> polarized, with the maximum of the HRS indicatrix shifted by 8° relative to the specular direction, which is interpreted as being due to the contribution of a fluctuating quadrupole to the nonlinear-optical response of the films. The estimated correlation length of spatial fluctuations of the nonlinear-optical polarization in the film is ~400 nm. These properties are associated with an islandlike structure formed by Gd ions inside LB structural units.
© 2000 Optical Society of America
T. V. Murzina, G. B. Khomutov, A. A. Nikulin, Th. Rasing, and O. A. Aktsipetrov, "Hyper-Rayleigh scattering in Gd-containing Langmuir–Blodgett superstructures," J. Opt. Soc. Am. B 17, 63-67 (2000)