Characterisation of an Acrylamide-based Photopolymer for Holographic Data Storage

An acrylamide-based photopolymer, formulated in the Centre for Industrial and Engineering Optics, was investigated as a recording material for holographic data storage applications. Holographic data storage (HDS) is an optical storage technique, which theoretically allows densities as high as tens of TB/cm2 with data transfer rates of many GB/s/. HDS has unique advantages, such as the ability to perform parallel data searches (associative recall) and implement novel encryption techniques. At present, many materials have been investigated to determine their suitability for use as HDS media. As yet, no one material possesses all the properties that are required to realise the huge benefits that HDS has to offer, these being large dynamic range, good optical quality, high sensitivity and resolution, temporal and dimensional stability, and low scattering. To aid in the characterisation of two of these properties, dynamic range and temporal stability, a test system for multiplexing plane gratings was developed. The system was designed to be modular so that its capabilities could be expanded upon at a later time, both in terms of optical setup and control software. The test system has the ability to muliplex sets of holographic gratings with equalised diffraction efficiency using either angular or peristrophic multiplexing or a combination of the two techniques. This enables the photopolymer’s dynamic range to be determined for many different formulations of photopolymer. In addition, it is possible to investigate the photopolymer’s temporal stability in terms of material shrinkage and diffraction efficiency by studying variations in the Bragg selectivity curve. The results of the dynamic range studies and temporal stability studies are presented in this thesis. Finally, work was carried out to investigate the possibility of storing bit data pages (2-dimensional binary patterns) in the photopolymer. A phrase-code multiplexing system was used to determine the necessary energy levels required to record data pages in the photopolymer. The recording period i.e. the period of time that it is possible to record data pages of good quality in the material, was also determined. All bit data page research was conducted in the Angewandte Physic, Westfalische Wilhelms-Universistat, Germany