| abstract |
The invention concerns the use, in non-linear optics, of azo dyes in which the diazo component is derived from an aniline or a five-membered aromatic heterocyclic amine which has one to three ring hetero-atoms selected from the group comprising nitrogen, oxygen and sulphur and which may be fused with a benzene, thiophene, pyridine or pyrimidine ring, the coupling component of the dye being selected from the series comprising the pyrrolidin-1-yl benzenes, piperidin-1-yl benzenes, pyrrolidin-1-yl naphthalenes and piperidin-1-yl naphthalenes. |