Photoinduced birefringence in di-azo compounds in polystyrene and poly(methyl methacrylate) guest–host systems

An investigation is presented of the optical storage capability, via photoinduced birefringence, for three di-azo compounds (Sudan dyes) incorporated into two polymer matrices, namely poly(methyl methacrylate) (PMMA) and polystyrene (PS). The optical birefringence was induced in the samples by using a diode-pumped frequency doubled Nd:YAG at 532 nm, while a He–Ne laser light at 632.8 nm was used to measure the induced birefringence in the sample. The results show lower dye mobility in PS than in PMMA matrices owing to the lower free volume that interferes with the efficiency of the birefringence photoinduced process. Some of the reasons for the lower efficiency of the induced birefringence of di-azo compounds compared to the mono-azo dyes are also discussed.