A fundamental investigation on the influence of deformation on the anodic dissolution behavior, i.e., corrosion, of metallic electrodes in aqueous solution has been conducted. The investigation was successful in developing a novel experimental method for studying the effects of deformation on corrosion. The development of the new method is established based on incorporating electrochemical techniques with those of holographic interferometry. In other words, the new method is capable of measuring microscopic deformation and the anodic dissolution current of the surface of metallic electrodes, simultaneously. Consequently, data on a stress corrosion test of Molybdenum in 0.75 N KCI is given in the present paper.

This paper discusses some of the important material property requirements for polymeric materials in electro-optic device applications, in particular, a detailed materials characterisation of a promising polymer that is not only high in electro-optic activity after poling, but has predicted long term thermal stability of the poled structure. This material is a methacrylic chain polymer with non-linear optical moieties attached as side chains through a spacer group. Progress in fabrication and characterisation of waveguides using this polymer is also reported.

Special features of the photopolymer system DMP128 can be exploited to form composites comprising a supporting matrix derived from the photopolymer and a dispersed second phase. Examples of two composite types are described here; composites with a nematic liquid crystal and composites used as waveguides. The diffraction efficiency of holograms containing the liquid crystal can be rapidly changed by applying an electric field. Periodic structures can easily be incorporated in the waveguide composites.

We propose the first monolithic optical clock distribution network on wafer scale integrated circuits (WSIC) . This new architecture can save real estate on VLSI chips and eliminate the packaging, alignment and interface problems of previously proposed architectures. A l-to-3 optical fan out for clock signal distribution application is demonstrated by utilizing a DCC multiplexed volume hologram on a thin quartz plate.

In this article are reported the results when four polymeric materials were used to record interference patterns. Radiation (10.6 ,im) used in the recording and reading steps came from a CO2 laser. To read the recorded patterns a thin film of aluminium was evaporated over them. It is shownthe behavior of the diffraction efficiency for the recorded interference gratings.

Systematic studies have been carried out on the performance evaluation of volume phase holograms recorded in methylene blue sensitized dichromated gelatin (MBDCG) to identify the conditions to be fulfilled to realize optimum difraction efficiency in such holograms.A noteworthy feature of the studies is that inexpensive nonstandard gelatin has been used. The studies have revealed that optimum diffraction efficiency can be achieved when, (a) the pH of the first development bath is kept around 65; (b) the concentration of axnmonium dichromate as prehardner is maintained around 0.5 '1. by weight of gelatin; (c) the concentration of ammonium dichromate and methylene blue photo.sensitizers is fixed around 30 gm/litre and 0.3 gm/litre respectively;and (d) no external electron donor is added.Further,it is found that the decrease in diffraction efficiency consequent upon the storage of holograms can be restored almost perfectly to the original level by reprocessing the holograms.Based on our studies, it is proposed that DCG can be used fruitfully as a model information recording medium to investigate such aspects as senility,information loss and restoration,in the context of the development of optical memories.

Studies of holographic and nonlinear responses for new recording materials can be easily performed with our new automated spatial frequency analyser. Consequently a complete characterization of new materials may be conducted rapidly in order to optimize the preparation techniques and real-time optical responses of studied materials . In the present work, three dye-polymers systems have been studied for polarization holography experiments. Results for colored polyvinyl alcohol (VIA) organic films will be discussed . The photoreaction mechanisms involved in those recording processes and some modern applications involving our erasable and/or peranent organic recording films will be present.

Polyimides have been experimentally studied for their potential application in optical interconnection networks. A total of nine commerically availables polyimides were evaluated in the form of planar slab optical waveguides. Analysis included measurement of optical properties such as transmission spectra, refractive index and loss. From this preliminary evaluation, four polyimides emerged as promising for application as channel optical waveguides. With these materials, multimode channel waveguides were fabricated with one of three methods, laser writing by thermal curing, laser writing with visible radiation in photosensitive polyimide and photolithography by contact printing, also in photosensitive polyimide. All three methods were relatively successful, yielding uniform, straight channels. Loss measurements suggest that laser writing by thermal curing has the potential to form waveguides with the lowest loss. However, attenuation in all cases was relatively high, typically 5 - 10 db/cm at 633 nm.

The feasibility of constructing graded-index (GRIN) Polymer Microstructure Waveguides (PMSWs) on various substrate surfaces, including semiconductors, conductors, insulators, and ceramics, has been consistently proven. The PMSW formed by Physical Optics Corporation (POC) is at least one to two orders of magnitude larger than those constructed by the state-of-the-art microstructure formation systems such as MOCVD and MBE. The polymer material used possess a large dynamic range of temperature stability (from -180°C to +200°C) and wide transmission bandwidth (from 0.3 pm to 2.7 im wavelengths). Local sensitization technique applied to PMSW has also been introduced to facilitate the formation ofplanar multiplexed holographic gratings for single wavelength 1-to-many fanouts and wavelength division (de)multiplexing (WD(D)M). Realization of such technology is useful for optical interconnection, signal processing and communication.

Planar polymer lightguides ofpoly-(methyl methacrylate) (PMMA) are doped with a UV sensitive material and an azo dye, sensitive for green or blue light (514, 488 nm) simultaneously. The UV-sensitive material is used for recording a permanent waveguide pattern while the azo dye is meant for a reversible light induced refractive index change. Although the azo dye is partly destroyed by the UV light and the photochemical reaction during waveguide formation, a light induced phase modulation in the guide is still possible in such bifunctional materials.

Real-time image subtraction and addition are realized by phase conjugation in an erythrosin- B-doped-polyvinyl alcohol film. In a degenerate four-wave mixing configuration, two mutually cross-polarized phase conjugate waves are generated: one is the phase conjugate wave by means of the degenerate four-wave mixing process, while the other is that of the holographic component by means of photo-induced irreversible chemical process. The image subtraction or addition can be performed by interference between two phase conjugate waves through an analyzer.

Polymer lightguides ofPMMA, doped with azo dyes are investigated with respect to their opto-optical or all optical properties. The TRANS-CIS photoisomerisation of the azo dyes leads to reasonable polarization dependent optically induced refractive index changes. These are studied in planar lightguides and in leaky guides. With light at the absorption edge all optical properties are studied leading to a possible application as bistable device.

Polymer lightguides ofPMMA, doped with azo dyes are investigated with respect to their opto-optical or all optical properties. The TRANS-CIS photoisomerisation of the azo dyes leads to reasonable polarization dependent optically induced refractive index changes. These are studied in planar lightguides and in leaky guides. With light at the absorption edge all optical properties are studied leading to a possible application as bistable device.

A combination of a liquid crystal cell with a polymer lightguide is investigated as a possible electrooptic device. In the interface region modulations up to 2o KHz are observed and investigated with evanescent fields of lightguide modes.

The study of rates of photochemical polymerization processes in three-dimensions requires the development of new approaches to following chemical changes in the transient time domain. We report, herein, fundamental studies of acrylate polymerizations leading to the development of a simple fluorescence probe for such studies.

Recent results are reported regarding the low temperature photochemistry and spectroscopy of several photoadducts of linear polyacenes blended into amorphous polymer hosts. The molecules studied are the anthracene-tetracene photoadduct, the 9-bromoanthracene-tetracene photoadduct, both isomers of ditetracene, and the D2h symmetric form of dipentacene (s-dipentacene). Low temperature fluorescence spectra and temperature cycling and matrix effects on photochemical hole burning spectra are presented. A discussion of the photochemical mechanism for some of the photoadducts which requires triplet-triplet absorption at low temperature is also presented.

Polymers can be generated with a pulsed laser source to initiate the polymerization process. Operating parameters such as laser repetition rate, pulse power, and photoinitiator concentration can change the rate and efficiency of the process. Recent work demonstrates that a wealth of kinetic and mechanistic information can be obtained by appropriate experiments. A review of the subject provides some insight into the possibilities of laser initiated polymerization.

Photopolymers are widely used in the electronic and printing industries. These materials usually consist of a plastisized polymer matrix, photoinitiator, monomer and a variety of chain transfer agents. Polymerization in photopolymer films is an interesting process but difficult to monitor. To facilitate the development of the new photopolymers and optimization of an imaging regime a method for the real-time nondestructive monitoring of reaction kinetics and molecular transport in photopolymers during photopolymerization was developed and applied. A change in the intensity of the fluorescence emitted by photopolymer films containing the fluorescent monomer, N-vinylcarbazole, is used to monitor the photopolymerization process. The mechanism of inhomogeneous polymerization in photopolymers is discussed.

Several aspects of the thermal and photochemical behavior of a main-chain nematic liquid crystalline polyarylcinnamate are discussed. Hypochromic and other effects that are attributed to chromophore aggregation are observed in the UV-VIS spectra of heated polymer films. These effects are more pronounced upon thermal annealing. They can only be eliminated by recasting the film out of solution. Irradiation (313nm) of the polymer leads to cyclobutane dimer and photo-Fries rearrangement products. Aggregated chromophores seem to form cyclobutane products in preference to photo-Fries products. Dimer to photo-Fries product ratios are reported as a function of phase type. Preliminary indications are that long-wavelength (365nm) excitation of aggregates leads to preferential cyclobutane formation. Only weak fluorescence can be observed from polymer films and this is tentatively attributed to monomeric chromophores. There is no evidence of emission from excited aggregates.

Laser induced holographic grating relaxation studies of thymorquinone (TQ) dissolved in amorphous poly(-methyl styrene) (PaS) and comphorquinme (CK) in poly(methyl methacrylate) (PMMA) have been carried out. Different types of lineshape associated with the relaxation of the diffraction intensity are observed and are interpreted in terms of various diffusion processes. Diffusion coefficients are obtained as a function of TO concentration from 0.3 to 20 weight percent in PcS and from 0.5 to 15 weight percent for CQ is PMMA. Above 0.5% the diffusion coefficient increases rapidly with increasing dye concentration. The temperature dependence of the self-diffusion coefficient follows the Williams-Landel-Ferry equation, whereas the mutual diffusion coefficient at higher dye concentration is Arrhenius. In addition, the self-diffusion coefficient of the dye molecule in polymer decreases very rapidly as the sample temperature is traversed across Tg. However, there is no detectable effect due to the onset of the glass transition on the mutual diffusion coefficient at finite dye concentration. The difference is interpreted as due to the plasticizing effect of the dye molecules. Free volume theory is used to interpret the concentration dependence of the diffusion coefficient.

Recording media based on the polymerization of monomers and oligomers commonly used in the Radiation Curing area, appear to be promising materials to record holographic patterns produced by laser sources emitting in the visible and near infrared part of the spectrum. A polymerization takes place only in the bright areas of the interference pattern and volume phase holograms exhibiting high diffraction efficiencies which can be viewed immediately after exposure, are created. Several examples of monophotonic and biphotonic systems will be discussed and presented.

A theoretical treatment of the behaviour of liquid crystalline side chain polymers containing photostationary mesogenic units such as azobenzene is given in the presented paper. The phenomenological theory gives both the dynamic and static characteristics of the material when irradiated with polarized light. It can be shown that the optical storage effect in these materials can be described as a photooptical induced rotational diffusion. The theory is able to describe phenomena which has been found earlier by our group.