Bit-Error and Noise Limitations on the Storage Capacity of Volume Holographic Memory Systems and Low Crosstalk Noise Code Criteria for Spatial Light Modulation Hologram Multiplexing.
Volume holographic storage takes full advantage of the volume space in a crystal and promises storage capacities on the order of one terabit per centimeter cube. However, efforts to match such a capacity which is based solely on wavelength and geometrical limitations have failed. A practical limit for holographic storage systems is set by the bit-error-rate, the readout speed, the number of holograms stored in the material, and noise. In this thesis, I present a model that estimates the storage capacity of holographic storage systems as a function of these parameters which helps define the bottlenecks in this technology. The analysis is carried out for the case where holograms are recorded in and read back from a volume material with known characteristics. In spatial light modulation hologram addresses determine the amplitude of crosstalk noise that is present in the reconstructed holograms. This noise sets an upper limit on the number of holograms that can be multiplexed in the volume storage material. Thus selection of hologram addresses is essential to the success of this hologram multiplexing method. In this thesis, I use Maxwell's equations to derive three-dimensional expressions for recorded and readout patterns when a plane wave interferes with an encoded reference wave in a photosensitive material. Based on the results, I find rigorous criteria for multiplexing many holograms in a volume material with low crosstalk noise and propose pseudorandom codes as a set of codes that satisfies such criteria.
- Pub Date:
- Physics: Optics; Engineering: Electronics and Electrical