The Azo Dye-doped Polymer Film Of Optical Storage Characteristics Of Study

With the development of science and technology, The films containing azo dyes doped polymers have been intensively investigated in the recent years because of their potential applications in optical storage and holographic optical elements. When the sample is irradiated with the laser light of appropriate wavelength, the azo molecules undergo reversible photoinduced anisotropy from trans form to cis form. The mechanism for optical storage in these materials has been attributed to a statistical reorientation of the azobenzene chromophors perpendicular to the polarization of the incident electric field of the pump laser beam.The photoinduced birefringence and holographic storage in methyl orange dyes (MO) doped polyvinyl alcohol (PVA) films were reported firstly in this thesis. The relationship between the photoinduced birefringence and the dye content and pumping power was investigated by using the writing light of 532 nm(double-frequency of Nd: YAG laser) and the reading light of 632.8 nm. The holographic experiments were carried out in these media. The curve of grating growth contains fast process and slow process which are respectively responsible to isomer grating and orientation grating. The relevant physical mechanism was elucidated.We chose Poly (methyl methacrylate) (PMMA) film containing push-pull azo dye as the material of optical storage. Holographic gratings were optically recorded by two beams from a He-Ne laser of 632.8 nm. It is significant in material application. The formation of holographic gratings accompanied by 532 nm irradiation was studied in detail. It was found that the effect of 532 nm laser to the holographic grating lay in two aspects: The acceleration effect of 532 nm laser to the formation of holographic grating is predominant when the intensity of 532 nm laser is low; while at relatively high intensities of 532 nm laser, the erasure is the main factor to the holographic grating. Moreover, the holographic grating was probed by 532 nm laser at low intensity and the dependence of the first order diffractive signal on the recording beamintensities was also presented.A kind of chiral azo molecule derived from amino acid, N-[4-(4-dodecyloxyphenylazo) benzoyl] -L-glutamic acid (C12-AZO-L-Glu), was investigated. The photochromism, photoinduced birefringence, and holographic recording in C12-Azo-L-Glu doped Poly (methyl methacrylate) (PMMA) films were studied. C12-Azo-L-Glu underwent a reversible tram-cis-trans isomerization in the polymer matrix. Photoinduced birefringence and holographic recording were performed by using Ar laser (488 nm) as writing beam and He-Ne laser (632.8 nm) as reading beam. The dependence of photoinduced birefringence and holographic recording on the intensities of writing beam was presented. The dynamic equation of Photoisomerization was used to elucidate the outcome. The results indicated that C12-Azo-L-Glu was a kind of ideal material for holographic recording and it allowed multiple uses without apparent fatigue.