Application of continuous-wave laser Z-scan technique to photoisomerization

We extend the application of the Z-scan technique to the investigation of refractive index change associated with the photoisomerization of azobenzene polymers. The performing of a Z scan is simplified, because only a cw laser is needed in the experiments. On the basis of an angular hole-burning model, a formula on the refractive index change is deduced. Measurements are also carried out on a poly(methyl methacrylate) film doped with disperse red 13 by the use of a Z-scan, and polarization effects in the refractive index change are revealed by employing a single beam. Both theoretical and experimental results show that the refractive index change effect associated with linearly polarized light is stronger than that associated with unpolarized light.