Spatial transfer of matter as a method of holographic recording in photoformers

Karpov, G. M.; Obukhovsky, Vyacheslav V.; Smirnova, T. V.; Lemeshko, V. V.

doi:10.1016/s0030-4018(99)00712-9

Cited by 95 publications

(58 citation statements)

References 12 publications

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“…26 We are currently developing coupled multiharmonic models, that incorporate these ideas. We are also exploring the affects of generalized nonlocal material response functions.…”

Section: Resultsmentioning

confidence: 99%

Adjusted intensity nonlocal diffusion model of photopolymer grating formation

2002

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Diffusion-based models of grating formation in photopolymers have been proposed in which the rate of monomer polymerization (removal) is directly proportional to the illuminating intensity inside the medium. However, based on photochemical considerations, the rate of polymerization is proportional in the steady state to the square root of the interference intensity. Recently it was shown that, by introducing a nonlocal response function into the one-dimensional diffusion equation that governs holographic grating formation in photopolymers, one can deduce both high-frequency and low-frequency cutoffs in the spatial-frequency response of photopolymer materials. Here the first-order nonlocal coupled diffusion equations are derived for the case of a general relationship between the rate of polymerization and the exposing intensity. Assuming a twoharmonic monomer expansion, the resultant analytic solutions are then used to fit experimental growth curves for gratings fabricated with different spatial frequencies. Various material parameters, including monomer diffusion constant D and nonlocal variance , are estimated.

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“…26 We are currently developing coupled multiharmonic models, that incorporate these ideas. We are also exploring the affects of generalized nonlocal material response functions.…”

Section: Resultsmentioning

confidence: 99%

Adjusted intensity nonlocal diffusion model of photopolymer grating formation

2002

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“…The differential equations provide a semi-analytical way of explaining why the index modulation is smaller when the separation between strips increases, that is to say, when low space frequencies are registered. Following a lot of new models were presented, taking into account different aspects of the formation hologram process [9][10][11][12][13][15][16][17]. All of these models assume a sinusoidal exposure along the x axis is:…”

Section: Introductionmentioning

confidence: 99%

3 Dimensional analysis of holographic photopolymers based memories

et al. 2005

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Abstract:One of the most interesting applications of photopolymers is as holographic recording materials for holographic memories. One of the basic requirements for this application is that the recording material thickness must be 500 µm or thicker. In recent years many 2-dimensional models have been proposed for the analysis of photopolymers. Good agreement between theoretical simulations and experimental results has been obtained for layers thinner than 200 µm. The attenuation of the light inside the material by Beer's law results in an attenuation of the index profile inside the material and in some cases the effective optical thickness of the material is lower than the physical thickness. This is an important and fundamental limitation in achieving high capacity holographic memories using photopolymers and cannot be analyzed using 2-D diffusion models. In this paper a model is proposed to describe the behavior of the photopolymers in 3-D. This model is applied to simulate the formation of profiles in depth for different photopolymer viscosities and different intensity attenuations inside the material.

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“…In literature, several models describing the diffusion of monomers in similar systems are found. 6,7 Other models in literature describe diffusion of reactive monomers in a polymer matrix. 8 However, these models predict that the most reactive monomer always migrates towards the regions of maximum UV intensity while earlier nuclear microprobe measurements on polymer a͒ Author to whom correspondence should be addressed; electronic mail: c.m.leewis@tue.nl gratings 4,5 suggest otherwise.…”

Section: Introductionmentioning

confidence: 99%

Reaction–diffusion model for the preparation of polymer gratings by patterned ultraviolet illumination

Leewis

Jong

IJzendoorn

et al. 2004

Journal of Applied Physics

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A model is developed to describe the migration mechanism of monomers during the lithographic preparation of polymer gratings by ultraviolet polymerization. The model is based on the FloryHuggins theory: a thermodynamic theory that deals with monomer/polymer solutions. During the photoinduced polymerization process, monomer migration is assumed to be driven by a gradient in the chemical potential rather than the concentration. If the chemical potential is used as the driving force, monomer migration is not only driven by a difference in concentration, or volume fraction, but also by other entropic effects such as monomer size and the degree of crosslinking of the polymer network, which is related to the ability of a polymer to swell. Interaction of the monomers with each other or the polymer is an additional energetic term in the chemical potential. The theoretical background of the model is explained and results of simulations are compared with those of nuclear microprobe measurements. A nuclear microprobe is used to determine the spatial monomer distribution in the polymer gratings. It is shown that two-way diffusion is expected if the monomers are both difunctional and have the same size. In some cases, if one monomer is considerably smaller than the other, it can eventually have a higher concentration in the illuminated regions, even when it has a lower reactivity. The model is used to simulate the grating formation process. This results in a calculated distribution of the monomer volume fractions as a function of position in polymer gratings. An excellent agreement with the nuclear microprobe measurements is obtained.

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Spatial transfer of matter as a method of holographic recording in photoformers

Cited by 95 publications

References 12 publications

Adjusted intensity nonlocal diffusion model of photopolymer grating formation

Adjusted intensity nonlocal diffusion model of photopolymer grating formation

3 Dimensional analysis of holographic photopolymers based memories

Reaction–diffusion model for the preparation of polymer gratings by patterned ultraviolet illumination

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