All-Optical Poling and Two-Photon Absorption in Heterocyclic Azo Dyes with Different Side Groups

We investigated the optical properties of heterocyclic azo dyes with different side groups prepared: as powders, in PMMA matrix, and side-chain polymers. We characterized the nonlinear optical effects of these compounds by Z-scan and all-optical poling techniques and supported these experiments with theoretical modeling. It was found that these materials show strong two-photon absorption cross sections exceeding 20 GM, which is 1 order of magnitude stronger than that of similar materials (azobenzene and p-amino­azobenzene). Our study reveals the dominant role of the side-chain system over the guest–host one and stresses the importance of the substituent in the efficiency of the poling process.