Modeling the photochemical kinetics induced by holographic exposures in PQ/PMMA photopolymer material

PQ/PMMA photopolymer: Modelling post-exposure

“…Under appropriate cosinusoidal holographic exposure [12][13][14], a grating can be formed in PQ/PMMA layer after a relatively short illumination or exposure time, i.e., t exp ¼60 s, see [13] and [14]. The largest refractive index contribution during exposure arises due to the nonuniform concentration distributions of PQ (and 1 PQ n ), as these dominate the strength of the grating formed [13,14].…”

“…Therefore the storage capabilities of self-processing photopolymer materials are under constant study with attempts being made to improve their ability to record low loss, mechanically stable, high diffraction efficient volume gratings in an inexpensive way. Among such materials PQ/PMMA layers [10][11][12][13][14] currently play a significant role as they have several properties that make them suitable for holographic applications [15,16], including as a data storage media [17,18] and in producing robust optical elements, i.e., solar concentrators [19].…”

“…Following exposure, appropriate post-exposure heat treatment of the material is typically applied, resulting in a more rapid diffusion of the excess unattached PQ molecules from the dark into the bright regions, leading eventually to their homogenous distribution inside the medium. This results in a significant change in the refractive index modulation [12,15,16,20]. After such treatment, it is the concentration distribution of the photoproduct PQ-PMMA alone which determines the grating strength.…”

Two-wavelength holographic recording in photopolymer using four-energy-level system: experiments and modeling

“…In holographic recording, the writing time is in the order of 1000 min. The diffusion length of PQ molecules in PMMA matrix at room temperature can be calculated to be in the order of submicrometers, [30][31][32] which is a fraction of typical fringe spacing of the interference fringe. Hence, the spatial modulation of the hologram will be affected.…”

Optimisation of photopolymers for holographic applications using the Non-local Photo-polymerization Driven Diffusion model

“…This Non-local Photo-polymerization Driven Diffusion (NPDD) model provides a comprehensive theoretical representation of the processes, which occur during free radical photo-polymerization. Thus enabling predictions to be made in a physically realistic way about the behaviour of a number of different photopolymer materials [1,2,8,[18][19][20], which possess very different material characteristics. In this paper, we examine in detail some of the predictions made by this NPDD model and analyse their impact on photopolymer material development.…”