Recording of holographic diffraction gratings in photopolymers: Theoretical modelling and real-time monitoring of grating growth

Aubrecht, Ivo; Miler, Miroslav; Koudela, Ivo

doi:10.1080/09500349808230641

Cited by 89 publications

(21 citation statements)

References 19 publications

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“…The polymerization causes a change and/or modulation of the density, which results in a refractive-index modulation proportional to the exposure

Q = I t

, i.e., the product of intensity and time. There are sophisticated theories to predict the temporal evolution of the diffraction efficiency, e.g., [47]. For our system, the nonlocal-response diffusion model of holographic recording might be suitable, a detailed theory developed in a series of papers by Sheridan and coworkers [48,49,50,51,52].…”

Section: Modeling and Data Evaluationmentioning

confidence: 99%

A Comprehensive Study of Photorefractive Properties in Poly(ethylene glycol) Dimethacrylate— Ionic Liquid Composites

et al. 2016

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A detailed investigation of the recording, as well as the readout of transmission gratings in composites of poly(ethylene glycol) dimethacrylate (PEGDMA) and ionic liquids is presented. Gratings with a period of about 5.8 micrometers were recorded using a two-wave mixing technique with a coherent laser beam of a 355-nm wavelength. A series of samples with grating thicknesses d0=10…150 micrometers, each for two different exposure times, was prepared. The recording kinetics, as well as the post-exposure properties of the gratings were monitored by diffracting a low intensity probe beam at a wavelength of 633 nm for Bragg incidence. To obtain a complete characterization, two-beam coupling experiments were conducted to clarify the type and the strength of the recorded gratings. Finally, the diffraction efficiency was measured as a function of the readout angle at different post-exposure times. We found that, depending on the parameters, different grating types (pure phase and/or mixed) are generated, and at elevated thicknesses, strong light-induced scattering develops. The measured angular dependence of the diffraction efficiency can be fitted using a five-wave coupling theory assuming an attenuation of the gratings along the thickness. For grating thicknesses larger than 85 microns, light-induced scattering becomes increasingly important. The latter is an obstacle for recording thicker holograms, as it destroys the recording interference pattern with increasing sample depth. The obtained results are valuable in particular when considering PEGDMA-ionic liquid composites in the synthesis of advanced polymer composites for applications, such as biomaterials, conductive polymers and holographic storage materials.

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“…The polymerization causes a change and/or modulation of the density, which results in a refractive-index modulation proportional to the exposure

Q = I t

Section: Modeling and Data Evaluationmentioning

confidence: 99%

A Comprehensive Study of Photorefractive Properties in Poly(ethylene glycol) Dimethacrylate— Ionic Liquid Composites

et al. 2016

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“…As noted in part I [1], polymerization and diffusion will result in some shrinkage and swelling during and post exposure. However, we assume that the total volume fraction is approximately conserved during exposure [8][9][10][11]: Table 1 shows the compositions of the materials tested. Applying equations (1) and (2), the various concentrations and volume fractions of the CTAs were determined along with the refractive indices of photopolymer layers before photopolymerization, i.e., n dark .…”

Section: Volume Fraction Analysismentioning

confidence: 99%

“…It is once again assumed that the total volume fraction is conserved, i.e., (t), are the volume fractions of monomer, polymer and background respectively, [8][9][10][11]. In equation (3), φ 1 (t) are the time varying first harmonic volume fraction components of monomer and polymer respectively.…”

Section: Volume Fraction Analysismentioning

confidence: 99%

“…CTA-2 is more effective in reducing the average polymer chain length, which is also consistent with the results presented in section 2. For the reflection geometry holographic recording (very high spatial frequency), by processing the results in table 4 using equation (11), the values of n 1 for standard, CTA-1, CTA-2 can be estimated as follows: (i) in the case of 4286 lines mm −1 , n 1 = {0.58, 0.67, 0.69} × 10 −3 ; and (ii) in the case of 4799 lines mm −1 , n 1 = {0.27, 0.33, 0.35} × 10 −3 . These results consistently indicate an accompanying improvement in the magnitude of the saturation refractive index modulation.…”

Section: Sf (Lines MMmentioning

confidence: 99%

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Non-local spatial frequency response of photopolymer materials containing chain transfer agents: II. Experimental results

Guo¹,

Gleeson²,

Shui³

et al. 2011

J. Opt.

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In part I of this paper the non-local photo-polymerization driven diffusion model was extended to include the kinetics of chain transfer and re-initiation, in order to analyse the effects of chain transfer agents on the system kinetics and to study their use in reducing the average polymer chain length in free-radical based photopolymer materials. Based on these results, it is proposed that one possible way to improve the material response at high spatial frequency is the addition of chain transfer agents. In this paper, the validity of the proposed model is examined by applying it to fit experimental data for an acrylamide/polyvinyl alcohol (AA/PVA) layer containing two different types of chain transfer agent (CTA): sodium formate (HCOONa) and 1-mercapto-2-propanol (CH 3 CH(OH)CH 2 SH). The effects on decreasing the average polymer chain length formed, by the addition of chain transfer agent, which in turn reduces the non-local response of the material, are demonstrated. These reductions are shown to be accompanied by improved high spatial frequency response. Key material parameters are extracted by numerically fitting experimentally measured refractive index modulation growth curves using the model. Further independent experimental confirmation of the reduction in the average polymer molecular weight is provided using a diffusion based holographic technique.

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“…Once we have measured the monomer and polymer concentrations, the refractive index of the photopolymeric layer can be calculated as a function of the volume fraction variations of each component using the Lorentz-Lorenz equation [21]:…”

Section: The Photopolymerization Reactionmentioning

confidence: 99%

Polymerizable Materials for Diffractive Optical Elements Recording

Fernández¹,

Fuster²,

Guardiola³

et al. 2018

Recent Research in Polymerization

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The technologies based on holographic and photonic techniques related to the optical storage and optical processing of information are rapidly evolving. One of the key points of this evolution are the new recording materials able to perform under the most specific situations and applications. In this sense, the importance of the photopolymers is growing spectacularly. This is mainly due to their versatility in terms of composition and design together with other interesting properties such as self-processing capabilities. In this chapter, we introduce the diffractive optical elements (DOE) generation in these materials and some of the most important parameters involved in this process. The deep knowledge of the material is essential to model its behavior during and after the recording process and we present different techniques to characterize the recording materials. We also present a 3D theoretical diffusion model able to reproduce and predict the experimental behavior of the recording process of any kind of DOE onto the photopolymers. The theoretical results will be supported by experimental analysis using a hybrid optical-digital setup, which includes a liquid crystal on silicon display. Besides this analysis, we study a method to improve the conservation and characteristics of these materials, an index-matching system.

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Recording of holographic diffraction gratings in photopolymers: Theoretical modelling and real-time monitoring of grating growth

Cited by 89 publications

References 19 publications

A Comprehensive Study of Photorefractive Properties in Poly(ethylene glycol) Dimethacrylate— Ionic Liquid Composites

A Comprehensive Study of Photorefractive Properties in Poly(ethylene glycol) Dimethacrylate— Ionic Liquid Composites

Non-local spatial frequency response of photopolymer materials containing chain transfer agents: II. Experimental results

Polymerizable Materials for Diffractive Optical Elements Recording

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