A demonstration holographic memory system using a spherical medium with angle multiplexing

Summary form only given.Holographic data storage holds the promise of data densities of approximately one bit per cubic wavelength of medium. In order to achieve this density using angular multiplexing it is necessary to store diffraction-limited holograms at an angular density consistent with the Bragg width of the individual holograms over all allowed angles. In the typical storage geometry employing crystals with flat polished faces, access to all angles is not possible due to refraction effects. We report the storage and retrieval of data in a holographic system employing a rotating spherical medium which allows access to all Bragg angles. Phase conjugate readout of the gratings allows diffraction-limited resolution using inexpensive highly-aberrating lenses. The medium in these experiments is the so-called DX crystal CdF/sub 2/:Ga which supports the formation of refractive index gratings through the optical excitation of bistable dopant atoms.