Melinda Schnoes

Recording media that exhibit high dynamic range for digital holographic data storage

A general strategy for fabricating thick, optically flat photopolymer recording media with high dynamic range (M/#) that exhibit low levels of recording-induced Bragg detuning for holographic data storage is presented. In particular, media with M/# values as high as 42 in 1-mm-thick formats are obtained. We believe that these results are the first demonstration of a holographic storage medium with a dynamic range of this magnitude. In addition, we report the holographic recording and recovery of high-capacity (480-kbit) digital data pages in these media, further illustrating their data-storage capabilities.

Temperature-induced changes in photopolymer volume holograms

Temperature-induced distortions of plane-wave holographic gratings recorded in low glass transition temperature (Tg∼26 °C) photopolymer media were measured. Changes in temperature affect the refractive index and dimensions of photopolymer materials, thereby rotating the angular Bragg selectivity of recorded volume holograms. From temperature-dependent measurements on a set of angularly multiplexed holograms, the out-of-plane coefficient of thermal expansion of a thin photopolymer film constrained between two rigid glass substrates is found to be 500 ppm/°C. These experiments suggest that the temperature sensitivity of photopolymer volume holograms may limit their use in many applications.

Photopolymer-filled nanoporous glass as a dimensionally stable holographic recording medium

The holographic recording characteristics of a photopolymer-nanoporous-glass composite are reported. An M/# of 3.2 is measured in this medium by angle multiplexing of a series of plane-wave holograms. In addition, the dimensional stability of the material is demonstrated by the negligible Bragg detuning of a set of angle-multiplexed holograms recorded with varying grating tilt angles and by the relative insensitivity of the detuning to changes in temperature.

Digital holographic data storage in photopolymer systems

We report on the holographic storage and recovery of multiple high capacity (800 X 600, 480 kbit) data pages in 250 micrometer and 500 micrometer thick photopolymer media. The data pages were recovered with raw bit error rates less than 5 X 10-3, the level correctable by current error correction strategies. Our results demonstrate that photopolymer systems can be fabricated with the optical quality and low level of scatter required for digital data storage.

Photopolymer media for digital holographic data storage

We report on the holographic storage of multiple digital data pages in photopolymer media. The results demonstrate the potential of these materials for high density data storage.