Linear and nonlinear optical properties of covalently bound C.I. Disperse Red 1 chromophore/silica hybrid film

The third-order nonlinearity of an organiceinorganic hybrid silica film covalently doped and dispersed with C.I. Disperse Red 1 was studied using the Z-scan technique. The micropores in the solegel derived silica matrix were smaller than the dye ligand which led to dye aggregation. A nonlinear refractive index of -3.4 × 10^-9 esu and a nonlinear susceptibility of 5.9 × 10^-10 esu were recorded at 1064 nm. The large blue shift of the absorption band due to dye aggregation resulted in an enhanced two-photon absorption. The observed nonlinearity is attributable to both two-photon absorption resonance and the refraction change induced by the enlarged π-delocalization conjugation between the dye and the silica matrix.