This PDF file contains the front matter associated with SPIE Proceedings Volume 6657, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

Holographic manipulation of nanoparticle assembly in polymer and its applications to holographic 3D recording and patterning are described. A statistical thermodynamic model is used to study the kinetics of multidimensional nanoparticle assembling in polymer under holographic illumination. Volume holographic storage using peristrophic multiplexing and nanoparticle pattering in silica nanoparticles-polymer composite films are also demonstrated experimentally.

Holographic photopolymers develop permanent index change via the polymerization and subsequent diffusion of monomer. It is well-known that to achieve high-fidelity recording, the rate of polymerization must be small in comparison to the rate of diffusion, particularly for strong exposures that consume significant fractions of the available monomer. When this condition is violated, polymerization is slowed in high-intensity regions by the local depletion of monomer, resulting in broadening of recorded features. This paper shows that a diffusing inhibitor has analogous dynamics controlled by the ratio of inhibitor diffusion rate to inhibition rate. When the ratio is small, inhibitor is locally depleted in bright regions, resulting in localized acceleration of polymerization. This causes recorded index features to be narrower than the incident optical exposure. Theoretical, numerical and experimental studies are used to illustrate this fact and show that this narrowing can be used to compensate for the broadening caused by monomer dynamics. Both effects are emphasized for rapid, strong recordings, suggesting that an inhibitor may be used to increase recording fidelity in this limit.

In the last three decades several kinds of organic mixtures for holographic recording were developed in order to achieve a new class of DVD-like optical memories for high-density optical data storage. The holographic materials should satisfy the following requirements: high sensitivity to blue light, low losses, high spatial resolution and long term stability. To this aim we developed new organic photosensitive mixtures based on only three components. We recorded high spatial frequency reflection gratings up to 7400 lines/mm with blue laser light (405 nm) by using a conventional holographic setup. We obtained a macro grating diffraction efficiency up to 67%, refractive index modulation over 0.01, optical shrinkage < 2 % and overall losses ~5%. In order to characterize data-storage materials independently on the experimental conditions, the sensitivity has been evaluated through the S parameter which takes into account the diffraction efficiency, recording light intensity, exposure time and sample thickness. The amazing obtained values of S >10⁵ cm/J evidences a very fast recording process with a very low writing intensity (less than 20 mW/cm²) corresponding to a recording energy density of few mJ/cm². The performance of these materials have been also tested in the microholographic geometry.

Holographic data storage materials are presented that are based on a thermoplastic host doped with narrow-band absorption dyes. The dyes are photosensitive and undergo non-reversible photobleaching reactions upon exposure. Samples were produced using different dyes and various concentrations in a polymer host with a focus on sensitivity and capacity of the media. A challenging obstacle for a successful dye-doped system is the inherent remaining photosensitivity of the material after the writing process. This paper will introduce the concept of a highly sensitive yet non-volatile dye-based data storage system. The chromophore is subjected to a post-treatment step at a second wavelength which removes the photosensitivity. The stored data can therefore be secured against degradation during read-out at the writing wavelength.

Carbazol-containing polymers were shown to be good reliefographic photosensitive substrates for holographic registration. Holographic images with satisfactory properties were obtained with carbazolic copolymers containing carbazolylethylmethacrylate and octylmethacrylate units and iodoform as sensitizer. The final goal of this study is to find the best copolymer formulation ensuring large amount of data stored with a high transfer rate and an optimized lifetime of the hologram and of the host polymer. It is then crucial to elucidate the involved photochemical mechanisms. We first carried out irradiations at 405 nm (wavelength of the laser diode used for holographic recording) in order to follow the photostructuration of the doped polymer. Spectroscopic analyses showed that the formation of a charge transfer complex is observed and its increase of concentration in the polymer could be followed versus exposure time. We also focused our attention on the durability of the hologram and of the polymeric matrix itself. Under irradiations representative of natural ageing (λ>300 nm), we have shown that the complex is successively formed and destroyed and that the photodegradation of the polymer matrix was also observed.

3D holographic gratings with variable periodicity represent a central part of an optical sensing system. Periodic spatial modulation of the refractive index in all three dimensions is holographically induced by multiple beam interference. The periodicity of the resulting volume diffractive optical structure is controlled by the recording beam geometry. The recording medium is a photosensitive polymer. An experimental setup for creating and analyzing such 3D gratings is presented as well as first results achieved in a 300 μm thick photopolymer sample.

Two active areas of research in the field of integrated optics are the coupling of on-chip waveguides to off-chip optical fibers and the reduction of circuit size which is dominated by the minimum bend radius of waveguides. Traditional approaches using mask-based lithography involve the complex etching of micro-mechanical on-chip mounts for the fiber or total-internal-reflection facets for sharp waveguide bends. Holographic photopolymers have several unique properties that enable a significantly simpler approach to both problems. Chief among these are the ability to be cast with low stress around embedded components and the ability to create localized 3D index structures. This is demonstrated by the fabrication of optical waveguides which couple directly to encapsulated fibers after making 90 degree bends off of encapsulated front-surface mirrors. The results are low loss and significantly simpler than existing approaches.

The sugar cane crystals (sucrose) are used as matrix to obtain computer holograms. We made a sugar solution (sugar in water) and it is irradiated with ultraviolet light, since the maximum absorption spectra is localized at UV region, to wavelength 200 nm. This step also corresponds to sugar photopolymer process. It is recorded applying conventional lithography technique and measures the parameter of diffraction efficiency. With the purpose to reduce the exposition time at UV radiation of this emulsion, we made studies with artificial organic colorant with azo components.

An artificial green colorant, composed by erioglaucine (Blue 1) and tartrazine (Yellow 5), was employed in a sugar matrix to improve the material sensibility and to make a comparative analysis of the diffraction efficiency parameter, for holograms replications, the holographic pattern was obtained by a computer and recorded in sugar films and in modified sugar (sugar-colorant). Conventional lithography and UV radiation were used. The results show that the behavior diffraction efficiency of the sugar-colorant films is slightly larger than in the sugar matrix under the same recording conditions.

Experimental techniques are described for recording holograms in dichromate gelatin doped with an organic dye. This material has excellent resolution, and increase the photo sensibility. We present some basic studies about the possible form of to storage information, and reported results. This material is cheap, easy of to use, and it decrease the register time.

We showing some properties using materials as dichromate polyvinyl alcohol (DC-PVA), it is doped with natural colorant, it were investigated and compared to the pure dichromated polyvinyl alcohol. The material increasing the sensibility, and present a good photo sensibility Preliminary studies shows, some properties with the ability to storage information, and present a technique to obtain holograms with these colored materials, and some experimental results. The best advantage of this DYE-DC-PVA holograms is the speed of recording.

The electro-optical changes of holographic gratings were analyzed when hologram formation was carried out in presence of applied voltage. Diffraction efficiency parameter of holographic gratings were studied in dichromated poly(vinyl alcohol) films and dichromated poly(vinyl alcohol) doped with nickel(II) chloride hexahydrate. The electrical changes of the materials were analyzed as a function of surface and volume resistivity.

This work presents experimental results of intensity changes by polarization conditions at the resultant diffraction patters. The substrate used as retarder plate was a commercial transparency film for use with plain paper copier (3M-PP2900^TM). The conductive material composition was introduce to dichromated poly(vinyl alcohol) by adding a metallic salt as nickel(II) chloride hexahydrate. Some electro-optical characteristics of organic conductive material that are used in the holographic gratings storage specifically when applied voltage.