Abstract

Organic crystals have been shown to possess large second- and third-order nonlinear optical susceptibilities. The origin of these susceptibilities has been traced to the electronic properties of the molecules composing these crystals. Although materials exhibiting second-order nonlinear optical processes require that a material be noncentro-symmetric, this class Is not limited to crystals. Orientationally ordered materials are formed by incorporating organic molecules possessing large molecular susceptibilities into a material lacking long-range order. If a phase transition exists aboye room temperature where molecular motion Is greatly enhanced, orientational order can be Imparted to this material by applying a strong electric field. This orientational order can be frozen in by cooling the material through the phase transition with the field applied. The resulting material belongs to the point group » mm and exhibits second-order nonlinear optical properties.

© 1987 Optical Society of America