Preparation and characterization of Irgacure 784 doped photopolymers for holographic data storage at 532 nm

Abstract

This paper presents the development of a thick photopolymer for holographic data storage at a wavelength of 532 nm. Irgacure 784, one kind of the titanocene photoinitiators, has been selected and doped to synthesize the photopolymers in this research. Using a two-step thermo-polymerization procedure two photopolymer samples have been fabricated, Irgacure 784 doped poly(methyl methacrylate) (PMMA) and Irgacure 784 doped epoxy resin. Samples of 2 mm thick have been fabricated. Holographic measurements show that Irgacure 784 doped epoxy resin is very sensitive at 532 nm and that it is capable of supporting holographic data storage at a ultra-fast recording rate of 760 Mb s −1. Mass spectrum measurement, solid state 1 H-NMR spectrum measurement, and thermogravity analyses (TGA) have been performed. The results reveal the physical mechanism of holographic recording in these samples, providing a guideline for a design strategy and fabrication technique to produce a low-shrinkage recording material for holographic data storage in the tera-byte information age.

Nonlocal photopolymerization kinetics including multiple termination mechanisms and dark reactions Part II Experimental validation

“…These mechanisms can include the generation of photoproducts, which absorb at the exposing wavelength, and also the production of other transient initiator states [15][16][17]. However, for the short holographic exposures (Յ5 s exposure), which are examined in this paper, it is assumed that the simple theoretical model used in the absorption analysis of the AA/PVA system is sufficiently valid in order to estimate the rate of generation of primary radicals R i ͑x , t͒ in the epoxy resin case.…”

A Review of the Optimisation of Photopolymer Materials for Holographic Data Storage

“…Lin et al [71] fabricated two photopolymer samples, Irgacure 784 doped poly(methyl methacrylate) (PMMA) and Irgacure 784 doped epoxy resin, using a two-step thermopolymerization procedure. Comparing the experimental results for Irgacure 784/PMMA to those produced using PQ/PMMA, the M# was improved by a factor of 1.9, and the sensitivity has been improved by a factor of 10.…”

Photoinitiation study of Irgacure 784 in an epoxy resin photopolymer

“…3,10,14,[17][18][19][20] In this study we follow Ref. 19 and assume that isomerization takes place before the photocleaving of the generated isomer.…”

“…Their inexpensive, self-processing capability and low loss make them promising materials for a variety of applications. [1][2][3][4][5][6][7][8][9][10][11][12] In order to reach their full potential, accurate material models based on reproducible experimental data sets will be necessary. In particular, such models are needed to identify and permit optimization of crucial operational parameters.…”

“…13 Numerous optical components are commonly produced using materials which undergo free radical photopolymerization, 2 and they are also widely studied as an optical data storage media. [4][5][6][7][8][9][10][11] Free radical photopolymerization can be initiated either by the reaction of an excited state photosensitizer dye with a coinitiator, e.g., an electron donor or an electron acceptor, producing free radicals, or by direct photocleavage of the photoinitiator molecule. 3,14 Useful photoinitiator systems have to meet a few basic requirements: ͑i͒ The photoinitiator system and polymerizable material must be thermally stable, ͑ii͒ they should exhibit strong absorption in the wavelength region of interest, and ͑iii͒ they should efficiently produce free radicals in order to start polymerization.…”