Nonresonant second-order microscopic nonlinear-optical susceptibilities (β) of a series of organic conjugated π-electron molecules were measured, using dc-induced second-harmonicgeneration. This study confirms structure–property relationships that affect β, including the electronic properties of substituents, the length of and type of π-electron system, molecular configuration, and dispersion. A quantity β0, based on a two-level model, is used, allowing trends to be discerned more easily by dividing out the effects of the dispersion of the first excited state. The second-order microscopic susceptibilities of materials based on cyanovinyl-substituted azobenzenes and stilbenes are found to be large. Details of the experimental configuration and method are also presented.
© 1989 Optical Society of America
Original Manuscript: November 17, 1988
Manuscript Accepted: February 21, 1989
Published: July 1, 1989
K. D. Singer, H. E. Katz, C. W. Dirk, J. E. Sohn, L. A. King, and H. M. Gordon, "Second-order nonlinear-optical properties of donor- and acceptor-substituted aromatic compounds," J. Opt. Soc. Am. B 6, 1339-1350 (1989)