| abstract |
Optical elements having non-linear optical properties comprising a compound of the formula:n wherein nD is an electron donor nA is an electron acceptor; n& W, X, Y & Z are each independently H or any group capable of attachment to the pyrazolyl ring; in which the molecules of the compound are aligned so that the element has a net non-centrosymmetry, a method for their preparation, optical devices comprising such elements, and compounds of formula I. |