We report the results of holographic and spectroscopic study of D2 dye doped PMMA and PS polymer compounds. The unusual non monotone relaxation dynamics observed in D2:PS compound shows the presence of unknown earlier excitation modes in this system. EXPERIMENTAL CONDITIONSAzo dye doped polymer guest-host systems attract very intensive studies for reversible optical storage. ' The understanding of photosensitivity mechanisms of these systems is thus an important challenge. We use, in the present work, dynamic holography and time resolved spectroscopy techniques to achieve this goal. New experimental results, concerning the photoexcitation and relaxation of azo dye doped PS and PMMA films, are reported. In particularly, we report, we believe for the first time, the observation of an unusual non monotone relaxation, which is observed in azo dye doped PS in the case of saturated holographic excitation. ''We have used Merck's D2 bisazo dye (containing two azo bonds) doped in mentioned above polymer films. The structural chemical formula of D2 is represented in the inset of Figure 1. We prepare several solutions for film preparation. The first one is the solution of D2 dye in THF (of concentration 0,44%) which is mixed for about 12 hours. The second one is of PS in THF (of concentration 15,98%) that is mixed for about 12 hours too. Then we take 2,4041g of PS solution and 0,0823g of D2 solution. The film preparation is conducted 1