Abstract

Most organic materials that have been proposed for purposes involving quadratic nonlinear optics are composed of elongated, sometimes quasi-one-dimensional molecules. Moreover, such traditional structures as paranitroaniline and asymmetric conjugated polyenes,¹ in which the quadratic nonlinearity is mainly driven by a highly directional intramolecular electronic charge transfer transition, are generally highly dipolar and have well-known related drawbacks: a detrimental tendency toward aggregation, prevailing centrosymmetric crystalline structures, and difficult crystallisation. A wealth of possibly exploitable more isotropic or fully three-dimensional organic structures are neglected because of this traditional strategy, which 1 propose to challenge by addressing the following questions:

© 1991 Optical Society of America