NATURE OF THE NONLINEAR 2ND-ORDER OPTICAL SUSCEPTIBILITY IN MOLECULARMATERIALS WITH C-2V MOLECULAR SYMMETRY

The method of second-harmonic generation at the wavelength 1.06 mu m i s used to study the nonlinear second-order optical susceptibility of p olycrystalline molecular materials with C-2e molecular symmetry belong ing to the group of 2,6-dibenzadiene substituted cyclohexanes. The mag nitude of the second harmonic signal is comparable to or greater than its value for polycrystalline urea and depends on the type of substitu ent (the stronger the donor properties of the substituent, the stronge r the signal). It is shown that in the majority of the compounds inves tigated the large nonlinear optical polarizability observed is associa ted with the octupole moment of the molecule. (C) 1997 American Instit ute of Physics.